Ruzairi Abdul Rahim

Ultrasonic Transmission-Mode Tomography Imaging for Liquid/Gas Two-Phase Flow

This paper details the development of noninvasive ultrasonic tomography for imaging liquid and gas flow. The transmission-mode approach has been used for sensing the liquid/gas two-phase flow, which is a kind of strongly inhomogeneous medium. Sixteen pairs of ultrasonic sensors have been used. By using low excitation voltage of 20 V, fan-shaped beam ultrasonic transmitters will emit ultrasonic pulses to the receivers. The investigations were based on the transmission and the reception of ultrasonic sensors that were mounted circularly on the surface of the experimental vessel. The algorithms used to reconstruct the concentration profile for two-phase flow using a fan-shaped beam scanning geometry were presented. By using a hybrid-binary reconstruction algorithm, real-time ultrasonic transmission-mode tomography has been developed. Experiments show that performance is acceptable with an image-reconstruction speed of 10 frames/s. The results of the experiments and possible future improvements were also discussed

Advancements in Transmitters and Sensors for Biological Tissue Imaging in Magnetic Induction Tomography

Magnetic Induction Tomography (MIT), which is also known as Electromagnetic Tomography (EMT) or Mutual Inductance Tomography, is among the imaging modalities of interest to many researchers around the world. This noninvasive modality applies an electromagnetic field and is sensitive to all three passive electromagnetic properties of a material that are conductivity, permittivity and permeability. MIT is categorized under the passive imaging family with an electrodeless technique through the use of excitation coils to induce an electromagnetic field in the material, which is then measured at the receiving side by sensors. The aim of this review is to discuss the challenges of the MIT technique and summarize the recent advancements in the transmitters and sensors, with a focus on applications in biological tissue imaging. It is hoped that this review will provide some valuable information on the MIT for those who have interest in this modality. The need of this knowledge may speed up the process of adopted of MIT as a medical imaging technology.

Electrodynamics Sensor for the Image Reconstruction Process in an Electrical Charge Tomography System

Electrical charge tomography (EChT) is a non-invasive imaging technique that is aimed to reconstruct the image of materials being conveyed based on data measured by an electrodynamics sensor installed around the pipe. Image reconstruction in electrical charge tomography is vital and has not been widely studied before. Three methods have been introduced before, namely the linear back projection method, the filtered back projection method and the least square method. These methods normally face ill-posed problems and their solutions are unstable and inaccurate. In order to ensure the stability and accuracy, a special solution should be applied to obtain a meaningful image reconstruction result. In this paper, a new image reconstruction method – Least squares with regularization (LSR) will be introduced to reconstruct the image of material in a gravity mode conveyor pipeline for electrical charge tomography. Numerical analysis results based on simulation data indicated that this algorithm efficiently overcomes the numerical instability. The results show that the accuracy of the reconstruction images obtained using the proposed algorithm was enhanced and similar to the image captured by a CCD Camera. As a result, an efficient method for electrical charge tomography image reconstruction has been introduced.

Neural network and principal component regression in non-destructive soluble solids content assessment: a comparison

Visible and near infrared spectroscopy is a non-destructive, green, and rapid technology that can be utilized to estimate the components of interest without conditioning it, as compared with classical analytical methods. The objective of this paper is to compare the performance of artificial neural network (ANN) (a nonlinear model) and principal component regression (PCR) (a linear model) based on visible and shortwave near infrared (VIS-SWNIR) (400–1000 nm) spectra in the non-destructive soluble solids content measurement of an apple. First, we used multiplicative scattering correction to pre-process the spectral data. Second, PCR was applied to estimate the optimal number of input variables. Third, the input variables with an optimal amount were used as the inputs of both multiple linear regression and ANN models. The initial weights and the number of hidden neurons were adjusted to optimize the performance of ANN. Findings suggest that the predictive performance of ANN with two hidden neurons outperforms that of PCR.

The Front-End Hardware Design Issue in Ultrasonic Tomography

This paper explains the front-end hardware design for ultrasonic tomography. The ultrasonic tomography system presented in this paper uses a noninvasive sensing technique with transmission-mode approach for investigating gas bubbles in an experimental column. Several explanations regarding the common tomography technique and the hardware preparation are also discussed. The sensory parts consist of 32 units of ultrasonic transceivers to form the fan-shaped beam projections. A low voltage of 20 V has been used to generate the ultrasonic burst tones. The electronic circuitry details, including the signal generator, the signal conditioning, and the signal acquisition strategy, are also presented. The results from this paper are useful for further development in ultrasonic tomography design.

Optical fibre sensors for process tomography

This paper describes an investigation into the use of an optical fibre sensor to measure the flow of pneumatically conveyed solid particles. Typical results for the mass flow rate of dry sand versus transducer output voltage are presented for a 1 mm diameter sensor fibre. The frequency bandwidth of the sensor is determined for a range of fibre diameters and compared with the calculated response obtained using spatial filtering considerations.

Hardware Implementation of Multiple Fan Beam Projection Technique in Optical Fibre Process Tomography

The main objective of this project is to implement the multiple fan beam projection technique using optical fibre sensors with the aim to achieve a high data acquisition rate. Multiple fan beam projection technique here is defined as allowing more than one emitter to transmit light at the same time using the switch-mode fan beam method. For the thirty-two pairs of sensors used, the 2-projection technique and 4-projection technique are being investigated. Sixteen sets of projections will complete one frame of light emission for the 2-projection technique while eight sets of projection will complete one frame of light emission for the 4-projection technique. In order to facilitate data acquisition process, PIC microcontroller and the sample and hold circuit are being used. This paper summarizes the hardware configuration and design for this project.

Segmented Capacitance Tomography Electrodes: A Design and Experimental Verifications

A segmented capacitance tomography system for real-time imaging of multiphase flows is developed and presented in this work. The earlier research shows that the electrical tomography (ECT) system is applicable in flow visualization (image reconstruction). The acquired concentration profile obtained from capacitance measurements able to imaged liquid and gas mixture in pipelines meanwhile the system development is designed to attach on a vessel. The electrode plates which act as the sensor previously has been assembled and fixed on the pipeline, thus it causes obscurity for the production to have any new process installation in the future. Therefore, a segmented electrode sensor offers a new design and idea on ECT system which is portable to be assembled in different diameter sizes of pipeline, and it is flexible to apply in any number due to different size of pipeline without the need of redesigning the sensing module. The new approach of this sensing module contains the integration intelligent electrode sensing circuit on every each of electrode sensors. A microcontroller unit and data acquisition (DAQ) system has been integrated on the electrode sensing circuit and USB technology was applied into the data acquisition system making the sensor able to work independently. Other than that the driven guard that usually placed between adjacent measuring electrodes and earth screen has been embedded on the segmented electrode sensor plates. This eliminates the cable noise and the electrode, so the signal conditioning board can be expanded according to pipe diameter.

Optical tomography system for process measurement using light-emitting diodes as a light source

We describe the development of a tomographic system by employing low-cost optical sensors. This sensor selection aims at producing a low-cost solution in visualizing a low dense solid particle conveyor system. The final aim of this project is to achieve real-time monitoring of solid particles having low concentration flow when being conveyed in a vertical pneumatic conveyor. The developed tomography system consists of 32 pairs of light-emitting diodes (LEDs) and silicon PIN photodiodes. These sensors are used to monitor the emitted radiation for fluctuations caused by particles interfering with the beam when passing through it. Each sensor output depends on the position of flow regime within the sensing zone. The relationships between the particle distribution and light attenuation effects are investigated by reconstructing the cross-sectional image through computer programming. A data acquisition system is used to digitalize analog signals from the sensor system and is manipulated by a personal computer in real-time mode. The results obtained from this investigation show that low-cost optical sensors are suitable for monitoring low and medium concentration flowing materials.

Novel Adjacent Criterion Method for Improving Ultrasonic Imaging Spatial Resolution

In this letter, we present a novel approach for improving spatial resolution in ultrasonic tomography. The proposed technique modifies a Back-projection (BP) algorithm in reconstructing tomography images. We used 32-ultrasonic transducer on a liquid column to perform the imaging process. Two phantoms were used to evaluate the proposed technique and compared with BP technique. The results showed that the proposed technique improves the spatial resolution and exhibits more accurate tomograms.