Department Publications

Neurotransmitters, such as dopamine and serotonin, are endogenous chemicals that enable neurons to communicate with one another throughout the body. Alterations in the levels of specific neurotransmitters are associated with various neuropsychiatric disorders. Dopamine (DA) - often known as the feel-good hormone – is primarily responsible for reward and motivation and is a key biomarker of Parkinson’s disease. Medications such as Levodopa alter its level in biological fluids, monitoring of which is important to ensure the proper therapeutic range for sufficient medication to cross the blood-brain barrier. Serotonin (5-HT) regulates mood, stress response, sleep, and autonomic function, and its dysregulation is implicated in depression, anxiety, and other neuropsychiatric disorders. Continuous or longitudinal monitoring of serotonin—especially in accessible biological matrices—can provide critical insights into …

Plasma-assisted processes are critical in semiconductor fabrication, where variations in plasma parameters can lead to reduced yield and device failure. This work presents the design and experimental validation of a non-invasive plasma density sensing system, intended for use in plasma-enhanced process reactors without requiring structural modifications. A prototype sensor array was developed to measure ion current via embedded electrodes and tested in a custom-built low-pressure plasma chamber. Experimental results show a strong linear correlation between chamber pressure and sensor current, confirming the sensor's ability to track plasma density trends. Supporting simulations and data visualization further demonstrate the feasibility of this approach for real-time, non-invasive plasma diagnostics.

There is a growing demand for novel nonisolated dc–dc power converters with the deployment of dc power distribution systems integrating renewable sources and energy storing elements. The load and source of these applications have different input and output voltage levels, and it is vital to avoid operating the interfacing power converters at extreme duty ratios. Therefore, engineers and researchers explore the power converter synthesizing techniques since the mid-1970s, fulfilling the above requirement besides the nonpulsating input and output current. Among them, the analytical synthesis method has gained popularity, although it gives rise to high-entropy equations. This article shows a simple yet powerful topology synthesis method based on the low-entropy equations that reveal the connection between the energy storing elements and switches. To this end, a set of design rules have been introduced in this …

The hybrid dc–dc converter family has desirable features to fulfil the performance matrix requirements of point-of-load converters. However, there are no well-established methods for synthesizing single and dual-path converters addressing design specifications. The existing connection matrix-based approaches are not helpful because they give rise to nonrealizable, redundant, and degenerative solutions. Therefore, a design-oriented and low-entropy equation-based single-path hybrid converter synthesis method is proposed in this article. To this end, general structures for the single- and multi-inductor converters have been proposed. They are based on the switched-capacitor cells. Therefore, a set of guidelines have been provided in this article to decompose a voltage gain polynomial for identifying the switched-capacitor cells. Moreover, a structured method to derive and approximate a converter gain polynomial …

An analytical method to synthesize a nonisolated multi-inductor (uncoupled) dc–dc converter having an arbitrary voltage conversion ratio is presented in this article. The proposed method provides a direct approach to synthesize the converter unlike the traditional topology synthesis methods, which involve circuit manipulations or selecting a connection matrix from a pool of possible matrices. As a result, the proposed method simplifies the topology synthesis of a converter having known properties to a four-step process. To this end, the voltage conversion ratio is decomposed, allowing to synthesize it using single inductor switching cells. The resultant single inductor switching cells can be either cascaded or differentially connected as pairs or embedded within a switching cell to realize a multi-inductor-converter. Several existing converter topologies have been synthesized to demonstrate the applicability and …

This paper discusses advances related to the integration of future mobile electronic THz systems. Without claiming to provide a comprehensive review of this surging research area, the authors gathered research on selected topics that are expected to be of relevance for the future exploration of components for practical mobile THz imaging and sensing applications. First, a brief technology review of integrated mobile THz components is given. Advances in III-V technology, silicon technology, and resonant-tunneling diodes (RTD) are discussed. Based on an RTD source and a SiGe-HBT direct detector, low-cost and compact computed tomography is presented for volumetric continuous-wave imaging at around 300 GHz. Moreover, aspects of system integration of mobile THz MIMO radars are discussed. Thereby, a novel phase-locked loop concept utilizing a high-stability yttrium-iron-garnet-tuned oscillator to …

Most of the electronic devices do not perform well in high temperature. In wafer fabrication, data propagation through thick metallic chamber walls need more transmitting power for successful data transmission. Measuring and transmitting temperature in closed metallic high temperature environment is a challenging issue. In this paper, a scheme to sense, process and transmit the data through fully closed and thick Aluminum chamber is proposed. The system is capable of sensing high temperature while handling for power fluctuations. Temperature is measured using tiny RTD resistors placed in different 7 locations up to 350 degree Celsius. The data is transmitted as radio-waves using ASK and FSK modulation techniques at the rate of 1 kbps. Processed demodulated data at the receiver-end provides the power supply voltage level, RTD locations ID, and the temperature in different locations of the IC inside the …

Machine vision has been widely deployed in many industrial applications. However, the accuracy and maturity level for the inspection of through-hole technology (THT) solder joints have yet to reach its ultimate goal. In this paper, we have presented a detailed explanation on a set of novel algorithms that can be effectively used to implement an automatic vision system that is capable of classifying the quality of THT solder joints very precisely. This vision system can be easily integrated into a soldering robotic system that performs automatic soldering on THT solder joints. The proposed vision system is capable of controlling the entire robotic system while providing automatic rework capability on the defective solder joints with much less user interaction. The experimental results indicate that the proposed system has an improved recognition rate and good resilience to noise and uneven illumination distribution.

Purpose Automatic Optical Inspection (AOI) systems that are extensively used in the industry of Electronics Manufacturing Services (EMS), performs the inspection of Surface Mount Devices (SMD). One of the main tasks of such an AOI system is to align a given PCB to the parameters of the corresponding PCB positioning system by a process called fiducial alignment. However, no detailed analysis has been carried out so far on the methodologies that can be used to have a very precise identification of PCB fiducial points. In our research, we have implemented an AOI system for the inspection of soldering defects of Through Hole Technology (THT) solder joints, which can be integrated to a desktop soldering robotic platform. Such platforms are used in environments where no specific lighting conditions can be provided within a surrounded atmosphere. Therefore, an AOI system that is capable of performing fiducial alignment of any given PCB under varying lighting condition is highly preferred. In this paper, we have presented a detailed analysis on feature extraction and template matching algorithms that can be used to implement a very precise fiducial verification process under normal lighting condition. Design/methodology/approach A detailed analysis and performance evaluation have been carried out in this paper on prominent image comparison algorithms that are extensively used in the field of image processing. Findings According to the analysis carried out in this paper, it could be observed that the combination of feature extraction and template matching algorithms gives the best performance in PCB fiducial verification process. Research …

An analytical method to derive a DC-DC converter topology for an arbitrary voltage conversion ratio is presented in this paper. The proposed method can be employed to derive DC-DC converters based on single and multiple inductors. The derivation of DC-DC converters having single inductor is explained in detail with a brief introduction to the multiple inductor derivation. The basic switching cells that can be incorporated into the single inductor based converters to obtain higher gain is introduced. Furthermore, their use to realize existing converter topologies is illustrated to validate the applicability of the proposed method to derive converters having an arbitrary gain.

Fitness related wearables have become ubiquitous in the recent past. Nevertheless, short battery life of these devices is still a pressing issue. Limited battery capacity in small form factor and power hungry continuous monitoring of accelerometer have been significant concerns in this regard. To address these issues we propose a novel low-power step counting solution based on an Electromagnetic energy harvesting mechanism. Extremely simple nature of the step counter removes the requirement of any step detection algorithm, thereby reducing the power consumption, while the energy harvester generates a portion of energy requirement prolonging the battery life.

Purpose Automatic Optical Inspection (AOI) systems, used in electronics industry have been primarily developed to inspect soldering defects of Surface Mount Devices (SMD) on a Printed Circuit Board (PCB). However, no commercially available AOI system exists that can be integrated to a desktop soldering robotic system, which is capable of identifying soldering defects of Through Hole Technology (THT) solder joints along with the soldering process. In our research, we have implemented an AOI platform that is capable of performing automatic quality assurance of THT solder joints in a much efficient way. In this paper, we have presented a novel approach to identify soldering defects of THT solder joints, based on the location of THT component lead top. This paper presents the methodologies that can be used to precisely identify and localize THT component lead inside a solder joint. Design/methodology/approach We have discussed the importance of lead top localization and presented a detailed description on the methodologies that can be used to precisely segment and localize THT lead top inside the solder joint. Findings It could be observed that the precise localization of THT lead top makes the soldering quality assurance process more accurate. A combination of template matching algorithms and colour model transformation provide the most accurate outcome in localizing the component lead top inside solder joint, according to the analysis carried out in this paper. Research limitations/implications When the component lead top is fully covered by the soldering, the implemented methodologies will not be able to identify the actual …

In this paper a transformerless voltage source sine wave inverter is proposed. A previously developed tri-state boost converter is utilized for the stepping up operation. In this topology the dynamic response of the inverter is increased, by avoiding the right hand plane zero in the converter's small-signal control-to-output transfer function when operating in the continuous conduction mode. The reference voltage for the tri-state boost converter is determined from the measured output voltage of the sine wave inverter and the calculated instantaneous value of the sine wave. The inverter with the tri-state boost converter and the inverter with a classical boost converter with voltage mode control and current mode control are compared for the dynamic response and efficiency. The analytical work of the design has been verified using a simulation. Furthermore, the boost converter is implemented in hardware to verify the boost …

Lankan agricultural community. The objective of this paper is to identify the methods and implementations that can be applied to the agricultural sector of Sri Lanka. While composing the framework with identified implementations the cost, scientific and technological knowledge of the farmers were taken into consideration.

The Axial Flux BLDC motors are relatively new, specially at higher power ratings over 10 kW. Therefore the designers face a lot of difficulties in designing and optimizing the motor for a given application. This paper presents a new method to optimize the performance in speed, torque, torque stability, power output, power density and motor dimensions in view of the cost and reliability for a given motor; specially to be used for traction purposes. By this method, the motor designers can easily choose the exact parameters of the motor to match the requirement and make sure of the optimization of the design. A software interface and simulation results are presented to check the level of optimization achievable with the system. This paper discusses a three phase axial flux outer rotor BLDC motor, but the core equations can be easily changed to simulate for any kind of motor with the same software and simulation interface.

The determination of the motor and battery specification is one of the major challenges in the electric vehicle designs, specially considering the different kinds of requirements and specifications in different designs. This paper discusses about a method of simulating a vehicle in given terrains and driver models for extracting the torque, power and battery usage; and hence get the most optimized set of parameters for the given design requirement. The simulation takes the driver as a fuzzy model and the overall vehicle as a non-linear model for calculating the motor and battery requirements according to the terrain, driver commands and traffic condition.

The determination of the motor and battery specification is one of the major challenges in the electric vehicle designs, specially considering the different kinds of requirements and specifications in different designs. This paper discusses about a method of simulating a vehicle in given terrains and driver models for extracting the torque, power and battery usage; and hence get the most optimized set of parameters for the given design requirement. The simulation takes the driver as a fuzzy model and the overall vehicle as a non-linear model for calculating the motor and battery requirements according to the terrain, driver commands and traffic condition.

Measurement of rainfall level in a certain place is a key requirement in recording meteorological data. The current measurements of the rainfall is done by a conventional volumetric vessel and a manual reading of the amount of water collected within a specific period of time. This research is focused on developing a methodology to measure the rainfall or the precipitation using a purely electrical method. The main drawback in the conventional method is the difficulty in interfacing the reading from the rainfall sensor with an electronic device. Using a weight sensor or a volume estimation method is not ideal for an integrated and robust digital weather station.