Recently, there has been a development of modern ballistic armor due to the creation of high performance composite materials based on aramid fibers with better weight reduction, higher strength and toughness. The use of metal for many critical applications has dramatically decreased since the new composite materials such as aramids provide excellent protection against handgun level threats. However, aramid fibers (Kevlars) are very difficult to machine by conventional machining techniques which cause various forms of material damage such as delamination and fiber pullout that normally occur during the machining of composite materials. The processes also result to high tool wear rates and poor surface roughness which ultimately may cause costly secondary rework as well as part rejection. As the use of these composite ballistic materials is anticipated to be increasing in large volume, the processing costs will be an important factor in order to provide cost-effective components and to gain competitive advantages over other materials. In this thesis, abrasive water jet (AWJ) machining of a representative ballistic material namely Kevlar-reinforced phenolic, an aramid fibers and a product of Du Pont was used to conduct the machining experiments in order to determine the viability of the machining process for manufacturing protective components with the above materials. Design of experiments (DOE) and analysis of variance (ANOVA) were used to measure systematically the various parametric combinations of pressure, standoff distance, traverse rate and abrasive flow rate on the kerf taper and the changes of surface roughness as a function of cutting depth for the Kevlar composite specimens. Stylus profilometry was used to measure the surface roughness and a visual inspection including scanning electron microscopy (SEM) was conducted. It was found that a smoother surface is obtained at the mid region along the depth of the specimens compared to that at the region of jet entry and jet exit. It was also observed that a higher jet pressure and a low traverse rate produces a smoother surface. Width of the kerf both at the jet entry and the jet exit was found to have a decreasing tendency with increase in traverse rate. Mathematical models were formulated to predict the surface roughness and kerf taper in terms of the selected cutting parameters mentioned earlier for the Kevlar composite to the cutting depths of 9.2mm. The cut surface of this material using a band saw machine was compared with that of the water jet in terms of surface roughness and damages incurred.

The present study aims to investigate the combined effect of moisture and temperature on the bending behavior of laminated composite cylindrical shell using an accurate laminate theory. Initially, standard benchmark results based on 3D elasticity solutions are used to assess the range of the applicability of available laminate models. Later, based on the realistic variation of displacements from the elasticity approach, a new 13 term higher order shear deformation theory HSDT13 was proposed for accurate analysis of cylindrical shell strip under hygrothermal and mechanical loading. The zigzag form of the displacement is incorporated via the Murakami zigzag function. Results are presented for both mechanical and thermal loading for various layups and they are validated against the derived elasticity solution. The significance of retaining various higher-order terms in the present model HSDT13, in evaluating the stresses and deflection for composite laminates is brought out clearly through parametric study. Useful results for combined hygrothermal loading are presented in tabular and graphical form. It is expected that the numerical results presented herein will serve as benchmark in future. Finally, the effect of temperature/hygroscopic dependent material properties on the hygrothermal analysis of laminated cylindrical shell strip is investigated and useful results were generated and presented in a tabular and graphical form.

This research explores the effect of physical conditions of varying age groups on photoplethysmographic (PPG) acquired through using an IR sensor. Easy Pulse Sensor Module interfaced to Arduino processing board are used to capture the PPG signal of subjects of known age group under similar working indoor environmental conditions and time of the day following strictly the university ethical rules. The Easy Pulse Analyzer processes the data so acquired and CoolTerm software based Graphical User Interface (GUI). The PPG sample data from the volunteers in the standing, lying, and jogging at the same spot conditions are examined and compared. Likewise, the PPG signals are obtained from the volunteers within the age group of 20s and 50s under similar different physiological conditions and a comparison is made in order to examine the behaviour of the PPG signal for varying age groups. The Kubios HRV biomedical software is used to study the PPG signals and report sheets are generated. The results are examined in terms of varying Heart Rate Variability (HRV) and Power Spectral Density (PSD) values. The results show the variation of the PPG signal in terms of its HRV, low frequency (0.04-0.15Hz) and high frequency (0.15-0.4Hz), LF/HF components and Power Spectral Density (PSD) results for different physiological conditions of varying age groups. The results also show that the values of HRV and HF components increase during the transition from sympathetic to parasympathetic physiological conditions. Furthermore, the PSD related components like absolute power (ms2) and percentage power (% power) are also increased with the HF values and HF components.

Developing light weight, stronger and flexible plate panels for engineering structure such as aircraft to withstand excessive vibration has been the interest of many researchers. Piezoelectric material has been a popular choice to attenuate the plate vibration actively and numerous techniques of optimal control and actuator placement has been proposed. This research discusses active vibration control on a simply supported thin plate using piezoelectric patches. Piezoelectric patches are used as exciters and actuators. The vibration control is focussed on frequency range with modal overlap factor equal and less than one, where the peaks of the frequency response function are differentiable to each other. Analytical derivation of a benchmark model consist of a simply supported thin plate with piezoelectric patches is obtained using Euler-Bernoulli model and Lagrangian energy method. MATLAB programme is written to compute the system energy, with and without controller, due to point force excitation and excitation from a piezoelectric patch. The optimal location of the collocated sensor-actuator and the optimal PID controller gains are obtained using a swarm intelligent algorithm called Ant Colony Optimization (ACO). The result is then compared with Genetic Algorithm (GA) and verified with enumerative method. Virtual experiment is performed using MATLAB-COMSOL Multiphysics integration to verify the optimal location of collocated sensor-actuator and controller gains. Finally, physical experiment is conducted to validate the findings.

Vibration control using piezoelectric (PZT) material has gained significant attention for its ability to behave as a sensor or actuator due to PZT direct and inverse effect. For control or excitation purposes, PZT patch actuator is embedded or attached on engineering built-up structures. Engineering systems such as aircraft, ships and automotive are considered built-up structures and dynamically they are thought of as being fabricated from many components that are classified as deterministic structure (DS) and non-deterministic structure (Non-DS). Adding a PZT actuator on a structure is equivalent to adding an external moment to the dynamics of the structure. However, the influence of adding input moment to a Non-DS is not fully understood due the complexity of the resulting wave; no mathematical representation has been established. In order to apply SEA method for input moments, a mathematical representation for moment generated by PZT patch in the form of average power is needed; so that a control system can be implemented. In this research, a simply-supported plate attached with a PZT patch is taken as a benchmark model. Ensemble average of power given by the PZT patch actuator to the plate when subjected to structural uncertainties is simulated using Lagrangian method and Monte-Carlo simulation. In addition, it is found out that the mathematical solution to estimate average power delivered to a structure can also be represented by mobility function. The findings of the research discovered that using moment mobility equation for a thin plate excited by a force couple, the power delivered by PZT actuator to a non-deterministic plate can be well-represented, particularly at high frequency range, therefore drastically cut computation time and cost. Parametric studies show that changing the patch location on the structure will not affect the ensemble average power supplied at high frequency. On the contrary, changing the patch size will change the power magnitude proportionally. In the second part of the thesis, the optimal gain values for a PZT patch controller in order to achieve maximum energy reduction for a non-deterministic thin plate is obtained using the Hybrid modelling method and mobility function. It is theoretically shown that by using larger numbers of point controllers on a Non-DS, better control effect can be achieved. A concluding remark can be made that findings from this research can be applied in SEA and the hybrid method used for analysing and vibration control of complex built-up structures.

In Free Space Optic (FSO) communication, the alignment between transmitter and receiver telescope is very important. The line of sight (LOS) of their optics must be aligned during the entire communication session. This is crucial in long distance data transmission. One of the factors that cause misalignment is vibration, either at the transmitter or the receiver. In this thesis, active vibration isolation (AVI) system which is able to actively isolate FSO devices from low frequency vibration from the ground is designed and developed. The main goal is to suppress vibration from the top plate of the system where the telescope of FSO system is mounted. A mathematical model of the isolator is derived and the prototype model of the AVI system is designed in SolidWorks. This prototype model is integrated with LabVIEW software to perform virtual prototyping in order to analyze the behavior of the system before the real prototype is developed. Controllers are designed and some simulation studies are performed in MATLAB for this AVI system. Then the real prototype is developed according to the design. An imbalance mass system is used as exciter of the system. Furthermore for cost saving factor, voice coil actuator which is modified from conventional loudspeaker is used as actuator of the system. Gain Feedback controller and LQR controller are implemented by using LabVIEW. The time domain and frequency domain analysis are done to analyze the performance of the active vibration isolation system with excitation frequency in a range of 0 Hz to 20 Hz. For system with excitation frequency 6 Hz, the reduction of displacement for gain feedback controller and LQR controller are 30.78 % and 93.56 % respectively while for the system with excitation frequency 12 Hz, the reduction of displacement is 30.86 % and 86.02 % for gain feedback controller and LQR controller respectively. The reduction of displacement of the system with excitation frequency 18 Hz for gain feedback controller and LQR controller are 61.23 % and 90.04 % respectively. According to experimental and simulation results, we can conclude that both controllers manage to suppress vibration at low frequency. LQR controller shows a better performance compared to gain feedback controller.

A free space optics (FSO) communication link which consists of a transmitter and a receiver FSO link head is used in transmission of data. The transmitter and receiver must be continuously aligned in order to successfully transmit data. Unfortunately, due to certain factors, the transmitter and receiver fail to have a continuous alignment resulting in misalignment that will effect transmission of data. Amongst the factors that cause misalignment include vibration either at the transmitter or receiver. In this work, an active vibration isolation system is proposed to actively isolate low frequency vibration from the surrounding environment of the transmitter and receiver mounting location which is usually located on rooftops or on top of high rise buildings. Before developing a real prototype of the active vibration isolation system, a virtual prototype is developed to observe the performance of the active vibration isolation test rig. Then, a real prototype is constructed which consists of an active vibration isolation test rig, a vibration exciter mechanism, a force generating actuator, sensors, and electronic controllers. Furthermore, it is necessary to design a controller to suppress the unwanted vibration by controlling the actuator force. Different controllers have been implemented in the system which include the simple gain feedback controller, Proportional Integral Derivative (PID) controller and Linear Quadratic Regulator (LQR) controller. The effectiveness of the controllers are evaluated through simulations and experiments on the lab-scale active vibration isolation system. The results are obtained by observing the peak amplitude of displacement and peak amplitude of frequency of the top plate of the active vibration isolation system. The proposed controllers are able to reduce vibration at excitation frequency of 9 Hz, the chosen frequency based on literature; the peak amplitude of displacement has been reduced by 34.31% using PID controller and 36.76% using LQR controller.

This research presents a nonlinear adaptive backstepping strategy for control of a pneumatic anthropomorphic robotic hand. An anthropomorphic hand with three fingers has been developed in this work. The fingers are driven by tendons and actuated by human muscle-like actuators known as Pneumatic Artificial Muscle (PAM). The high nonlinear dynamics of these actuators and the inherent hysteresis in their behaviour lead to the modelling and control problems that cause a lack of robustness in the hand`s performance. The robotic finger and the PAM actuator have been mathematically modelled as a nonlinear second order system based on an empirical approach. An adaptive backstepping controller has been designed in two design steps based on the nonlinear second order system model for position control of the pneumatic anthropomorphic hand. In the design procedure the estimator of the system uncertainty is incorporated to the proposed control law which is extended for grasping objects with changing weights using a slip detection strategy. In addition, a cascade control system is developed by combining a conventional PID control, as the inner pressure control loop, with the adaptive backstepping control as the outer position control loop. Simulation and experimental test have been conducted using an experiment setup to evaluate the performance of the designed controller. Based on both simulation and experimental results, the adaptive backstepping position controller is capable to compensate the uncertain coulomb friction force of PAM actuator achieving the desired angular trajectory with RMSE of hysteresis behaviour in range of 0.09o - 0.18o and RMSE of angular position control in range of 0.05o - 0.11o. The cascade controller has shown a stable supply of pressurized air with average settling time of 0.38 s - 0.57 s. In terms of force control, the robotic hand is able to maintain grasping objects when their weight is increased up to 500 g by detecting the slip signal generated by the force sensor. Therefore, based on the obtained results, the controller is capable of tracking the desired position accurately and the pneumatic anthropomorphic hand is able to prevent the object from dropping when its weight is increased. For future researches, the adaptive backstepping position controller can be used to overcome other uncertain parameters such as the viscous friction. The further pneumatic hand can also be improved by increasing the number of the robotic fingers and DOFs to improve its manipulation and grasping ability.

In general energy is a hot topic in the news nowadays: increased consumption, increased cost, depleted natural resources, our dependence on foreign sources, and the impact on the environment and the danger of global warming. Therefore, wind energy has great potential to lessen our dependence on traditional resources like oil, gas and coal and to do it without as much damage to the environment. Moreover, wind energy is playing a critical role in the establishment of an environmentally sustainable low carbon economy. The purpose of this thesis is to give wind turbine engineers information about a controller design and simulations of autonomous wind turbine system with variable-speed for permanent magnet synchronous generator (PMSG) and a system for storing energy based on appropriate controller. The proposed stand-alone hybrid wind/energy storage system is mainly consisting of a (PMSG) driven by wind turbine and feeds isolated load through DC-link. The DC-link is considered as uncontrolled rectifier, DC/DC converter and DC/AC converter. A lead-acid battery (LAB) is connected in parallel to the DC-link through charge/discharge controller. Adaptive fuzzy PID (AFPID) controller is used to control the duty ratio of the DC/DC converter and maintaining the DC-link voltage constant at its desired value. Also, another AFPID controller is used to control the battery charge/discharge regulator when the wind power and/or load varies. The power desired by the connected loads can be successfully supplied and delivered by the assumed wind generation unit and energy storage system using the adaptive fuzzy proportional-integral-derivative controller. The suggested hybrid wind-storage energy system with the proposed AFPID controller is examined through a step changes in both load and wind speed. Moreover, the system is examined in case of without control and in case of applying conventional PID controller. Simulation results are presented that there a better prediction of the electrical parameter waveforms especially in case of applying the proposed adaptive fuzzy PID controller.

Substantial evidence suggests that practices associated with Japanese Manufacturing Management (JMM) can yield a superior competitive advantage in terms of productivity, quality and provide overall successful business performance. With most of the studies are based on the experience of manufacturing companies in the developed countries, not much attention has been paid to the developing countries. To examine the transfer of the best practice of the JMM locally and obtain the impact of the adoption and adaptation of the JMM, an in-depth case study was conducted in a Malaysian automotive company. This is to identify what are the changes in terms of the philosophy and practices undertaken by the automotive company and ascertain the impact of the JMM on its manufacturing and financial performances. The elements of business performance from the viewpoint of manufacturing based on safety, quality, cost and delivery were quantified and examined. These elements are safety, Parts Per Million (PPM), in-line Defect per Unit (DPU), First Time Quality (FTQ), cycle time, productivity, efficiency and stock level. All elements were quantified since the first year of the adoption and viewed over time to track the trend of achievement. The results show a positive impact to the automotive plant manufacturing performance. For example, safety index has reduced to 0 major accident occurrences. The PPM and In-line DPU have improved by 98% and 91% respectively. The FTQ has improved by 167% and cycle time was reduced from 20 minutes to 6 minutes. The productivity has increased up to 43% whilst the efficiency was at 99.9%. The stock level was reduced from half month to 3 days after the adoption of the JMM. The results of the financial performance also show the profitability of the plant. The revenue has increased up to 92% after the JMM adoption, the percentage of expenses has reduced from 11.04% to 3.06% giving an improvement of 72% whilst the net profit has increased from 5.33% to 8.15%. The Return of Asset (RoA) and Return of Equity (RoE) also show slight improvement despite the effects from the restructuring exercise, tsunami calamity and fluctuation in Japanese exchange rate. In addition, the upward trend for Inventory Turnover Ratio (ITR) during the 3-year period of JMM adaptation had showed that the local company had well managed the inventory level. From this, it can be concluded that the business performance of the automotive plant under study has improved due to the JMM adoption and adaptation.

Electroencephalogram (EEG) signal based research is ongoing for the development of simple, user friendly, robust, efficient brain computer interfacing (BCI) devices/systems. Motor imagery related EEG signal classification is one of the main challenges in designing of a BCI system. An advanced and simple classification technique for motor imagery related BCI system has been developed. Fisher Linear Discriminant Analysis (FLDA) has a very low computational requirement, which makes it suitable for BCI system. Motor imagery based EEG dataset, collected by the world renowned BCI Group from Graz University of Technology, Austria, has been used. Initially the signal is extracted into features. The power spectral density technique has been used to extract the non-linear features over some frequency components in motor imagery based EEG signals. In training phase FLDA, Mahalanobis Discriminant Analysis (MDA), Quadratic Discriminant Analysis (QDA), Cauchy and Gaussian Radial Basis (GRB) classification techniques have been used for designing a motor imagery based BCI system. Then the optimized classifier MDA has been chosen. But in evaluation phase, FLDA performs better than MDA. This classification technique separates the extracted signals into possible classes by taking the means and variances between two classes. Then percentage of accuracy has been measured to detect the motor imagery movement. In addition, the probabilistic accuracy has been measured by using Cohen's kappa. It obtains more than 98% of accuracy and around 95% kappa in average in training phase using MDA. In evaluation state, they are 46% and 39% accuracies using FLDA and MDA respectively. For contrastive justification, some other classification techniques have also been used to compare the obtained results. Result depicts that the MDA classifier could be a preferable classification technique for both training and evaluation for detecting different motor imagery related brain states.

One of the most dangerous aeroelastic failure phenomenons is flutter. The flutter characteristic is different for each type of aircraft depends on the wing geometry and its operational region of subsonic, transonic or supersonic. Prior to performing flight flutter test, extensive numerical simulations and Ground Vibration Test should be conducted where the structural finite element modes and the experimentation results should be matched otherwise the numerical simulation model could be rejected. In the present work, the simulation of supersonic wing equipped with external stores of missiles on the wing had been analyzed at high supersonic region. The structural mode shapes at each generated frequency mode are also visually presented. The analysis is carried out using FEM software of MSC Nastran. The wing flutter with the external stores has been simulated at different altitudes. The result shows that the flutter velocity is sensitive to the flight altitude. For this reason, the flutter analysis is conducted also for a negative altitude. The negative altitude is obtained by considering the constant equivalent speed-Mach number rule at flutter speed boundary as a requirement in standard regulation of transport aircraft. The achieved flutter speed results at all altitudes have been set as the constraint to perform an optimization about the wing weight. The optimization processes have been performed by replacing the aluminum skin of the wing with Kevlar/Epoxy composite using steepest descent method. There are 5 processes of simulation have been performed by reducing the skin thickness respectively and observing the changes of flutter speed at every altitude. The results of weight reduction of the wing skins, the wing structure, and the whole weight for operation have been presented using graphical method. Further reduction of weight have been studied by reducing the ribs thickness of each region with condition the flutter speed of the case study should not below the baseline flutter speed results. The final result of Kevlar/Epoxy composite skin wing shows that the clean wing weight using composite can be reduced about 56.3% compared to the baseline. The final analysis of Kevlar/Epoxy composite skin wing continues by replacing the composite material with Graphite/Epoxy composite skin to study the effect of high modulus of elasticity of the present wing. The final result of this analysis shows that the weight of the clean wing can be reduced about 62% with higher flutter speed achieved compared to the baseline.

One of the most important capabilities of MPLS is to map traffic on paths established with traffic engineering principles, resulting in load balancing and fault tolerance of the underlying network. Traffic engineering deals with performance optimization and evaluation so that the overall performance for a network can be enhanced. Traffic Engineering with Link Coloring (TELIC) is an algorithm that assigns LSP’s to incoming traffic requests that enter an MPLS-DiffServ domain in a service aware manner. TELIC routes the best effort traffic preferably on separate links, away from the links carrying premium traffic. TELIC is shown to achieve remarkable success in routing EF or premium trunks separately with the DF flows. However, the DF rejection ratio is higher in TELIC as compared with other TE algorithms. This thesis proposes an enhancement for TELIC and SHORTD in order to increase the bandwidth allocation ratio for best effort traffic. Default Forwarding Trunk Splitting (DFTS) is a new algorithm developed and integrated with TELIC and SHORTD. This algorithm splits the rejected DF trunks across the domain into several smaller trunks and routes them on separate preferred links. DFTS has been developed in Visual C++ using object oriented design. TELIC’s performance with and without DFTS algorithm is measured by using it on a specific set of traffic requests that arrive at networks built with two different topologies such as ISP and Disjoint Multipath. The same traffic sets and topologies are used to measure SHORTD’s performance with and without DFTS.

Ion-selective electrode (ISE) sensors have been widely used in diagnostics, food security, and environmental monitoring applications owing to their low-cost and straightforward fabrication processes. However, monitoring physiological ions in real-time remains a challenge where conventional ISEs suffer poor sensitivity, limit of detection, and lifetime due to the sensing membranes of conventional ISEs, where ions were not efficiently converted into electrons. Therefore, this project aims to utilize nanomaterials of poly(3,4-ethylenedioxythiophene):polystyrenesulfonate as all-solid-state transducers to improve the sensitivity, limit of detection, and lifetime of the sensor. Moreover, this work aims to develop all-solid-state potassium ion-selective electrode (AS-K+ISE) sensors for detection and quantification of potassium ions (K+) in aqueous media. This research is also to evaluate and validate the sensor performance of the AS-K+ISE sensors by monitoring dynamic K+ changes in aedes mosquito larvae. The effects of modifying low-cost screen-printed carbon electrodes (SPCEs) with poly(3,4-ethylenedioxythiophene):polystyrenesulfonate (PEDOT:PSS), reduced graphene oxide stabilized in polystyrenesulfonate (rGO:PSS), and their composite (rGO:PSS-PEDOT:PSS) on the electrical conductivity and electrochemical reversibility of electrochemical sensor performance were characterised in terms of peak current (Ip), peak-to-peak potential separation (ΔEp), shift in peak potentials (Ep_shift), and effective surface area (Ae). Cyclic voltammetry (CV) results revealed transducer rGO:PSS-PEDOT:PSS has synergistic effect of PEDOT:PSS and rGO:PSS, where PEDOT:PSS has high peak current (Ip) suggesting fast electron transfer kinetics at the electrode-electrolyte interface, and rGO:PSS is reversible as evidenced by small ΔEp and Ep_shift. Owing to PEDOT:PSS having the highest peak current of 1.637 mA which is 23 folds higher than rGO:PSS, AS-K+ISE sensors were fabricated by drop-casting potassium-selective membrane (KISM) onto PEDOT:PSS/SPCEs. Potentiometry measurements were used to determine limit of detection, sensitivity, linear range, lifetime, response time, and selectivity of AS-K+ISE sensors of varying K+ concentrations. The AS-K+ISE sensors can detect as low as 0.01 µM of K+, with a near-Nernstian slope of 59.6 mV per decade within a linear range between 0.1 mM and 100 mM. The lifespan extends to at least 24 weeks, with instantaneous response of 3-10 s toward increasing K+ concentrations. The AS-K+ISE sensors showed a superior selectivity toward K+ over interfering ions Na+, and was successfully evaluated to detect varying K+ concentrations in aqueous media. Finally, the ability of the developed AS-K+ISE sensors was validated by monitoring dynamic K+ changes in aedes mosquito larvae. The results demonstrated performance of all-solid-state sensors based on screen printed electrodes that have performance of sensitivity, selectivity, and lifetime compared to microfabricated electrodes, paving efforts towards a low cost with high performance sensors for biomedical and environmental applications.

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The use of renewable resources is growing since fossil fuels have already been exhausted and they will last only for a few years to come. Wind power is one form of renewable energy that can be harnessed using wind turbines. Many improvements in the design of wind turbines are continuously increasing, and still, a lot must be made. The primary objective of this project is to conduct a performance analysis (power coefficient, Reynolds number, turbulent level) with different airfoils for a small capacity horizontal axis wind turbine. Computational Fluid Dynamics (CFD) is adopted as a method of analysis. However, CFD procedures are hardware intensive and computationally expensive. Furthermore, freely available simple tools called QBlade is computationally inexpensive, and it can be used for performance and design analyses of horizontal and vertical axis wind turbines. In the present research, an effort has been made to use QBlade for performance analysis of a small capacity horizontal axis wind turbine using selected prospective airfoils. In this study, four airfoils (namely, NACA 4412, SG6043, SD7062 and S833) have been selected and investigated in QBlade at different Reynolds numbers, and different tip speed ratio. Overall, it has been found that the power coefficient values of NACA 4412 at different tip speed ratios are higher compared to the other three airfoils. However, in terms of lift and drag, SG6043 showing the highest lift coefficient compared to the other airfoils. The wind resource in Comoros altered through the year with a wind speed of 4 m/s to 5.5 m/s. Based on the performance analysis from QBlade, NACA4412 was selected to design a small capacity horizontal axis wind turbine. The range of power generated from our wind turbine is 0.5 kW at 3 m/s to 1.2 kW at 6 m/s. with this wind condition a small size of a wind turbine is suitable to satisfy the project of the design and analysis of low capacity horizontal axis wind turbine at any location. Moreover, the design of small capacity horizontal axis wind turbines will be helpful to maintain stable electricity which is still one of the problems facing Comoros Island.

In this research a comparative analysis and implementation of Simultaneous Localization and Mapping (SLAM) algorithms for indoor mobile robots has been conducted, the purpose of which was to identify a possible area of improvement for future implementations. Robot are widely being used for daily tasks and as such require a technique to be able to easily navigate indoor environments, specifically small maps for helper robots, however simple methods such as dead reckoning and wireless beacons are unreliable. To resolve this problem a new method is being researched upon which is SLAM. SLAM algorithms which are commonly known, accepted by experts in robotics and are compatible with the Robot Operating System (ROS) have been selected for this study. They are GMapping, Hector SLAM and Karto SLAM. Each method is comparatively analysed with various parameters such as computational complexity which is a measure of how complex the algorithm is with respect to the amount of steps and calculations needed, Central Processing Unit (CPU) usage load which measures how much the processor is being used and scenario-based efficiency which takes into account the performance based on different scenarios such as different speeds, map sizes and obstacles. Additionally, the analysis and selection is based on validation techniques such as Corner Detection & Matching, K-Nearest Neighbours and Map Completeness conducted on simulated data. Based on the comparative analysis performed via MATLAB, Hector SLAM was found to be the most appropriate technique for indoor robots in small maps. This technique was implemented on the robot platform and real-world tests conducted. The chosen method i.e. Hector SLAM managed to successfully generate fully visible maps in small indoor locations with numerous features. However, maps with larger sizes or smoother features were not as efficient.

Ammonia is poisonous and harmful to environment. Ammonia is the most common pollutant in water streams and most of them come from agricultural, industrial, and domestic wastewater. The biggest problem for current method in ammonia monitoring detection is too much time taken to examine the water quality and the process is complicated. This is because the machine is not portable and the examination cannot be done at the measurement site. In addition, the effect of different concentration of ammonia and the distance of UV needs to be analyze to improve the measurement of output voltage to its optimum. The objectives of this study are to develop a portable PEC-based UV-assisted ammonia monitoring system using the TiO2-based sensor and analyze the data using fuzzy logic approach. This can help to shorten the time of examination of the water quality, portable to everywhere and can give more precise estimation of ammonia concentration. The basic item of this experimental setup are ammonium samples, ultraviolet (UV) light, TiO2-based sensor in photoelectrochemical cell (PEC) structure, microcontroller interfacing system and fuzzy logic system. We executed an experiment that measure the voltage generated with digital multimeter and our ammonia detection system using Arduino and make sure the error of voltage differences between them is low to make sure the output is accurate. Then, we varied the ammonia concentration and the distance of UV light from TiO2-based sensor to measure the output voltage. The measured data was analyzed using fuzzy logic approach to estimate the output voltage. Lastly, the fuzzy logic method is also used in reverse the calculation to predict the ammonia concentration based on the output voltage and UV distance. UV assisted TiO2-based ammonia sensor in PEC structure was successfully fabricated and developed into a portable device for measuring the voltage at different ammonia concentrations. The fuzzy logic approach for estimating the output voltage was successfully designed. As for the conclusion, analysis of ammonium concentration using TiO2-based sensor system and fuzzy logic approach can be used to advance the ammonia monitoring and estimate the output in shorter time.

Free Space Optics (FSO) has become one of the most promising technologies whereby optical transceivers transmit high bandwidth laser beams directly through the air. FSO offers extra inherent advantages which include fast and easy deployment by saving time and cost, license free spectrum, and has immunity to radio frequency interferences. In spite of these advantages, FSO is very sensitive towards atmospheric phenomena because it solely employs the air as transmission medium. Hence, atmospheric effects greatly affect the FSO transmission performances. Very few researches were conducted to study feasibility of FSO from earth-to-satellite links. None of these studies investigate the vulnerability of FSO links towards environmental effects from ground to space in tropical regions. Therefore, this research aims to provide feasibility analysis on establishing FSO links from earth-tosatellite, especially Low Earth Orbit (LEO) satellite. It evaluates the impact of several atmospheric phenomena that occurs in tropical regions specifically Malaysia. A measuring system was setup at Faculty of Engineering, International Islamic University Malaysia (IIUM) Kuala Lumpur campus in order to collect rain intensity, visibility variations, and received signal level from 800 m long FSO link concurrently. The FSO links availability has been predicted by estimating the effects of geometrical attenuation, absorption, scintillation, haze attenuation, and rain attenuation. The analyses are based on the prediction models as well as from the measured data collected from experimental FSO links. It was found that FSO links could be well established at LEO satellite during clear weather conditions with most sophisticated available optical devices, while during hazy conditions, the link depends on the visibility range. At 10 km visibility and 50 degree elevation angle, 52 dB link margin is achieved. During rainy event, the highest availability of establishing the FSO links is at 99.9% provided elevation angle must be higher than 50 degree. Note that, elevation angle and beam divergence angle are critical parameters trade in FSO slant path links that must be resolved to obtain a successful optical wireless system. Finally, the result of this analysis will contribute sufficient information for applying FSO in longer distances and determining the operability of FSO system and will be a benchmark for future designs.

One module of back converter is simulated using a forward quad-transistor topology. The 1: N stepping-down transformer is an effective component with galvanizing performance. Transistors are fitted with a diode while keeping the coil protected from spikes and fly-back issues. These configurations can be used in a modular structure, thereby reducing power losses of electronic components of the circuit, thus ensuring better analysis while enhancing efficiency and performance, thereby reducing design cost as well as being an integral part of hot swap features. Modules are stacked in parallel at the output for applications that increase the power rating. The proposed model structure of the Input Series Output Parallel (ISOP) module is selected for analysis under both steady and dynamic performance. The areas concentrated and explored in this research of the proposed configuration topology with considering voltage transient spikes and power loses. The circuit is simulated using PSIM Powersimtech with clearly state and emphasizing the modularity and transistors switching. The experiment has been conducted using Arduino Mega board to generate PWM and reduce the cost of the module. The result obtained from the two module using four transistor forward configuration shows the output voltage levels for different duty cycle values. Three value of duty cycle are determined by setting the duty cycle to be at 40% as the benchmark. Then, the duty cycle is set to 30%, 50% and 75%, which is later compared to the benchmark duty cycle, giving the output as expected accordingly. Depending on the switching frequency, the duty cycle and the input voltage, the output voltage will be valid as long as the duty cycle is set exactly at 50%. The current spikes and the output voltage stability are investigated by first determining the full bridge DC-DC converter topology. It shows that by increasing the switching frequency to 10 kHz and keeping the duty cycle to be at 50%, will produce less overshoot and system efficiency of 95% based on the simulation and measurement of the time taken for the output voltage to be at 30% overshot voltage. The input voltage is set to be at 48 V resulting best stability of the two modules connecting in series at the input. The effect of the switching frequency on the output will be optimized as long as the value of the duty cycle is set at 50% which then will reduce the spikes and hence achieving the objectives of this research, but however at the same time increasing the frequency at high level will reduce the output voltage and hence it need control strategy to get maximum power efficiency.