Low-power adaptive control scheme using switching activity measurement method for reconfigurable analog-to-digital converters

Power consumption is a critical issue for portable devices. The ever-increasing demand for multimode wireless applications and the growing concerns towards power-aware green technology make dynamically reconfigurable hardware an attractive solution for overcoming the power issue. This is due to its advantages of flexibility, reusability, and adaptability. During the last decade, reconfigurable analog-to-digital converters (ReADCs) have been used to support multimode wireless applications. With the ability to adaptively scale the power consumption according to different operation modes, reconfigurable devices utilise the power supply efficiently. This can prolong battery life and reduce unnecessary heat emission to the environment. However, current adaptive mechanisms for ReADCs rely upon external control signals generated using digital signal processors (DSPs) in the baseband. This thesis aims to provide a single-chip solution for real-time and low-power ReADC implementations that can adaptively change the converter resolution according to signal variations without the need of the baseband processing. Specifically, the thesis focuses on the analysis, design and implementation of a low-power digital controller unit for ReADCs. In this study, the following two important reconfigurability issues are investigated: i) the detection mechanism for an adaptive implementation, and ii) the measure of power and area overheads that are introduced by the adaptive control modules. This thesis outlines four main achievements to address these issues. The first achievement is the development of the switching activity measurement (SWAM) method to detect different signal components based upon the observation of the output of an ADC. The second achievement is a proposed adaptive algorithm for ReADCs to dynamically adjust the resolution depending upon the variations in the input signal. The third achievement is an ASIC implementation of the adaptive control module for ReADCs. The module achieves low reconfiguration overheads in terms of area and power compared with the main analog part of a ReADC. The fourth achievement is the development of a low-power noise detection module using a conventional ADC for signal improvement. Taken together, the findings from this study demonstrate the potential use of switching activity information of an ADC to adaptively control the circuits, and simultaneously expanding the functionality of the ADC in electronic systems

Stimulating scientific minds among early secondary students in Malaysia: a pilot study using ‘engineering and electronics made fun’ approach

This paper discusses the development of scientific thinking at an early stage of secondary education in Malaysia. Since the engineering aspects were introduced using ‘Electronics Made Fun’ approach, this pilot study was targeted at the first stage of secondary education. This is because at this stage, the students show signs of maturity in thinking and would be able to understand the concept of science and engineering at a greater extent. This study was conducted on 36 Form 1 students from Sekolah Menengah Agama Nilai, which the genders were divided equally. The aims of the study are to introduce electronics engineering in a fun and easy-to-understand concept, and to bridge the gap between universities and schools in Malaysia. This study was conducted in three stages: 1) Educating the students using information and notes, 2) Practical aspects of the study, where the students were given hands-on experiences using electronics kits and components, and 3) Implementation of knowledge and skills through group projects. Before the study was conducted, only 16.7% of the students can define proper concept of science and engineering, whereas only 19.4% of them were familiar with electronics components. After five weeks of regular meetings and activities with 34 contact hours, almost 94.4% of the students responded well in defining science and engineering. Interestingly, as much as 91.7% of them would like to attend such programme again in the future. This pilot study has paved the path towards empowering STEM and developing scientific minds at early stage of education in Malaysia

Generation of microsecond ytterbium-doped fibre laser pulses using bismuth telluride thin film as saturable absorber

Bismuth telluride (Bi2Te3), a type of topological insulators, is currently in hot pursuit due to its unique physical properties. Therefore, this paper describes a simple Q-switched Ytterbium-doped fiber laser (YDFL) by using Bi2Te3 thin-film as saturable absorber. The few layers Bi2Te3 film was fabricated using optical deposition technique and subsequently, was used in an all-fiber, YDFL setup. As a result, a self-starting Q-switching pulses were first occurred when the laser pumping power reached 88.6 mW. As the pump power level increased, the observed pulses repetition rates had increased steadily from 17 to 29.63 kHz. Hence, this work demonstrated that Bi2Te3 thin-film can be used to successfully generate Q-switching pulses at 1-micron region and is well suited for many photonic applications operated at this wavelength region

Metal Oxide Coated Optical Fiber for Humidity Sensing Application: A Review

Humidity measurement in biomedicals, industry and electronic manufacturing applications needs an accurate and fast measurement of relative humidity by the sensor. In recent years, electronic sensors are utilized in the market, but optical humidity sensors provide several advantages over it. This paper reports the classification of optical fiber humidity sensors based on their working principles, such as fiber Bragg gratings, interferometers, and resonators. Along with the mentioned optical fiber structures, their fabrication process, equipment required for humidity sensing and the coating technique used are explained in this review. Recently, metal oxide semiconductors have been widely used as sensing material, specifically in humidity sensor applications. Thus, this paper explores optical fiber humidity sensors based on the three working principles mentioned, all of which incorporate metal oxide coatings. This review reveals that the most commonly used metal oxide for optical fiber humidity sensing is graphene oxide. This is because graphene oxide offers high sensitivity, fast response and recovery time over the other types of metal oxide. A large number of oxygen-containing groups on the surface and edge of graphene oxide also contribute to humidity sensing performance since it can permeate and absorb more water molecules. The use of hybrid nanomaterials is recently discovered and their potential as emerging coating material for optical applications are not fully exploited yet. Thus, there is still an opportunity for improvement in terms of sensitivity, response and recovery time in the context of optical fiber humidity sensor

3D-DIoU: 3D Distance Intersection over Union for Multi-Object Tracking in Point Cloud

Multi-object tracking (MOT) is a prominent and important study in point cloud processing and computer vision. The main objective of MOT is to predict full tracklets of several objects in point cloud. Occlusion and similar objects are two common problems that reduce the algorithm’s performance throughout the tracking phase. The tracking performance of current MOT techniques, which adopt the ‘tracking-by-detection’ paradigm, is degrading, as evidenced by increasing numbers of identification (ID) switch and tracking drifts because it is difficult to perfectly predict the location of objects in complex scenes that are unable to track. Since the occluded object may have been visible in former frames, we manipulated the speed and location position of the object in the previous frames in order to guess where the occluded object might have been. In this paper, we employed a unique intersection over union (IoU) method in three-dimension (3D) planes, namely a distance IoU non-maximum suppression (DIoU-NMS) to accurately detect objects, and consequently we use 3D-DIoU for an object association process in order to increase tracking robustness and speed. By using a hybrid 3D DIoU-NMS and 3D-DIoU method, the tracking speed improved significantly. Experimental findings on the Waymo Open Dataset and nuScenes dataset, demonstrate that our multistage data association and tracking technique has clear benefits over previously developed algorithms in terms of tracking accuracy. In comparison with other 3D MOT tracking methods, our proposed approach demonstrates significant enhancement in tracking performances

Noncontact optical displacement sensor using an adiabatic u-shaped tapered fiber

A simple noncontact displacement microfiber sensor using adiabatic U-shaped tapered fiber is proposed and demonstrated. The microfiber is fabricated using a systematic fiber flame brushing technique, where the fiber waist diameter is proportional to the duration of the heating cycles. The sensor is capable of measuring a wide displacement distance up to 12 mm. A sensitivity of 0.2 dB/mm is recorded at a minimum tapered diameter of 8 µm. In comparison with the previous works of using Fresnel reflection method, the results of our proposed method show significant improvement in sensing range, which is indicated by distinct inclination of the loss slope. The microfiber probe shows a promise for a sensitive sensing at low development cost

Generation of Microsecond Ytterbium-Doped Fiber Laser Pulses using Bismuth Telluride Thin Film as Saturable Absorber

Bismuth telluride (Bi2Te3), a type of topological insulators, is currently in hot pursuit due to its unique physical properties. Therefore, this paper describes a simple Q-switched Ytterbium-doped fiber laser (YDFL) by using Bi2Te3 thin-film as saturable absorber. The few layers Bi2Te3 film was fabricated using optical deposition technique and subsequently, was used in an all-fiber, YDFL setup. As a result, a self-starting Q-switching pulses were first occurred when the laser pumping power reached 88.6 mW. As the pump power level increased, the observed pulses repetition rates had increased steadily from 17 to 29.63 kHz. Hence, this work demonstrated that Bi2Te3 thin-film can be used to successfully generate Q-switching pulses at 1-micron region and is well suited for many photonic applications operated at this wavelength region. © 2019 Penerbit Universiti Kebangsaan Malaysia. All rights reserved

Generation of dual-wavelength ytterbium-doped fibre laser using a highly nonlinear fibre

This paper describes the dual-wavelength operation in the 1060 nm region by applying an ytterbium-doped gain medium fiber and a highly nonlinear fiber (HNLF) as the wavelength selective filter. Due to its nonlinear properties and birefringence co-efficient, the HNLF also functions as a stabilizer for dual-wavelength fiber laser operation. Results from the experiment show that the fluctuated power of the system is less than 0.6 dB when continuously run for 20 min, indicating the system's stability. The spacing of the dual-wavelength output is obtained by fine-tuning the polarization controller within the fiber ring laser setup. The spacing ranges between 2.7 nm-21.05 nm

Effects of Tungsten Disulphide Coating on Tapered Microfiber for Relative Humidity Sensing Applications

Tungsten disulphide (WS2) is a two-dimensional transition-metal dichalcogenide material that can be used to improve the sensitivity of a variety of sensing applications. This study investigated the effect of WS2 coating on tapered region microfiber (MF) for relative humidity (RH) sensing applications. The flame brushing technique was used to taper the standard single-mode fiber (SMF) into three different waist diameter sizes of MF 2, 5, and 10 µm, respectively. The MFs were then coated with WS2 via a facile deposition method called the drop-casting technique. Since the MF had a strong evanescent field that allowed fast near-field interaction between the guided light and the environment, depositing WS2 onto the tapered region produced high humidity sensor sensitivity. The experiments were repeated three times to measure the average transmitted power, presenting repeatability and sensing stability. Each MF sample size was tested with varying humidity levels. Furthermore, the coated and non-coated MF performances were compared in the RH range of 45–90% RH at room temperature. It was found that the WS2 coating on 2 µm MF had a high sensitivity of 0.0861 dB/% RH with linearity over 99%. Thus, MF coated with WS2 encourages enhancement in the evanescent field effect in optical fiber humidity sensor applications

Metal Oxide Coated Optical Fiber for Humidity Sensing Application: A Review

Humidity measurement in biomedicals, industry and electronic manufacturing applications needs an accurate and fast measurement of relative humidity by the sensor. In recent years, electronic sensors are utilized in the market, but optical humidity sensors provide several advantages over it. This paper reports the classification of optical fiber humidity sensors based on their working principles, such as fiber Bragg gratings, interferometers, and resonators. Along with the mentioned optical fiber structures, their fabrication process, equipment required for humidity sensing and the coating technique used are explained in this review. Recently, metal oxide semiconductors have been widely used as sensing material, specifically in humidity sensor applications. Thus, this paper explores optical fiber humidity sensors based on the three working principles mentioned, all of which incorporate metal oxide coatings. This review reveals that the most commonly used metal oxide for optical fiber humidity sensing is graphene oxide. This is because graphene oxide offers high sensitivity, fast response and recovery time over the other types of metal oxide. A large number of oxygen-containing groups on the surface and edge of graphene oxide also contribute to humidity sensing performance since it can permeate and absorb more water molecules. The use of hybrid nanomaterials is recently discovered and their potential as emerging coating material for optical applications are not fully exploited yet. Thus, there is still an opportunity for improvement in terms of sensitivity, response and recovery time in the context of optical fiber humidity sensor