Theses & Dissertations

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https://hdl.handle.net/20.500.14170/209

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Browsing Theses & Dissertations by Department "Universiti Malaysia Perlis"
  • Publication
    A computational fluid dynamic analysis of prolonging survival in the microvascular vein grafting
    ( 2014)
    Muhd Nur Rahman Yahya
    A digital artery disease in the upper extremity is uncommon to happen but the revascularization procedure is still needed. As action taken, the surgical vein bypassing or vein interposition is performed. However, one or more internal diameters of the applied Reverse Saphenous Vein Graft (RSVG) are blocked and severely narrowed due to the irregular geometry formation such as internal diameter mismatched and over the length kink after the revascularization. In previous researches, the irregular geometry formation, the size discrepancy and bent in the vessel caused the abnormal blood flow and initiated the thrombosis. Furthermore, their previous works were also supported by clinical theory. The objective of this study is to investigate the effect of the blood flow on internal diameter mismatched and over the length kink of the RSVG models that relates to their long term survival. A Three-Dimensional Computational Fluid Dynamic (3D CFD) method is employed to investigate the velocity, the pressure gradient and the Wall Shear Stress (WSS) on ideal straight and irregular geometry of the RSVG models. For this research, the pulsatile laminar blood flow demonstrates non-hydraulically flow in irregular geometry of the vein graft models compared to an ideal straight model even in a steady state laminar blood flow test. As a conclusion, the results showed high value in the velocity, the pressure gradient and the WSS in the mismatch problem but low value in the velocity, the pressure gradient and the WSS in the over length kink problem. Any abnormal blood flow behavior will initiate the formation of the thrombosis and reduce the vein graft survival.
      2  11
  • Publication
    A new flexible cross correlation (FCC) code for optical CDMA systems
    ( 2014)
    Mohd Rashidi Che Beson
    There are tremendous interest in applying code division multiple access (CDMA) techniques to fiber optic communication systems. This technique is one of the multiple access schemes that is becoming popular due to its channel allocation flexibility, asynchronously operation, enhanced privacy, and increased capacity in bursty networks. The performance of optical CDMA (OCDMA) systems are highly dependable on code designed properties. In this thesis, a new Flexible Cross Correlation (FCC) code for OCDMA system is designed, simulated and validated. The FCC code has numerous features such as unfixed cross correlation function with shortest code length, easy to build, and adaptability to accommodate variance number of users and weights. The FCC code is designed based on matrix combinatorial where the tridiagonal code matrix was adopted in developing the algorithm of this FCC code. This research examines the theoretical and simulation aspects in the case of incoherent signal from the broadband light source utilizing AND subtraction detection technique at the receiver side. The results revealed that the FCC code can accommodate 150 users, where FCC code offers 66%, 172%, 650% and 900% improvement as a contrast to 90, 55, 20 and 15 numbers of users for Dynamic Cyclic Shift (DCS), Modified Double Weight (MDW), Modified Frequency Hoping (MFH)and Hadamard codes, respectively, for a permissible bit error rate (BER) of 10−9. The FCC code indicates optical received power Psr of −25 dBm, thus, the detection system is more sensitive via utilizing FCC code. The performance of OCDMA codes were simulated using OptiSystem software from Optiwave TM. The performance of the systems were characterized by referring to the BER, bit rate, optical received power Psr and fiber length. The results shown that the FCC code performs adequately for 45 km as opposed to 21 km for MDW code within bit rate of 155 Mbps and BER of 10−9. In this work, AND subtraction detection technique is employed at the receiver end in order to reduce the receiver complexity, and improve the system performance in terms of distance and number of active users. It has been shown through theoretical and simulation results, the performance of the system with AND subtraction detection technique improved significantly. Based on the validation of theoretical and imulation results employing back-to-back (B2B) transmission, a receiver's power marginal of −36 dB is obtained at a bi rate of 155 Mbps and BER of 10−9 over 10 km fiber length.
  • Publication
    A novel zero cross correlation code for optical code division multiple access system
    ( 2012)
    Anuar Mat Safar
    Optical Code Division Multiple Access (OCDMA) techniques have shown outstanding capabilities in sharing multiple users simultaneously in access network. The purpose of this study was to develop a new spectral amplitude coding (SAC) in OCDMA code. In particular, we tried to minimize multiple access interference (MAI), consequently diminish the phase induced intensity noise (PIIN) by using this new code with the main characteristic of zero cross correlation in its property. This code was investigated and analyzed for its performance in the network system. Another aim was to find out the components and parameters used in order to optimize the performance of the code. Finally, the analysis was validated by comparing theoretical studies with the simulation results. The method of combinatorial matrix was applied in developing this zero cross correlation (ZCC) code. By using SAC incoherent OCDMA techniques, we were able to mitigate the PIIN effect in the system performance. The study of system performance methodology in ZCC code was conducted and used to generate the mathematical derivation for the code performance theoretically.The simulation was conducted with optimization of the parameters involved to obtain the best performance in the system. The validation of the theoretical results was confirmed through this simulation analysis. The great contribution of ZCC code was that there was no overlapping of bit ‘1’ among users and absolutely orthogonal for any number of users and weights. The code structure was very flexible especially in changing code parameter such as the number of users and the number of weight. The code demonstrated an excellence in signal security due to the random code structure. Our performance analysis showed ZCC code has a better performance compared to other codes in the same class of SAC. It could also accommodate a higher number of users simultaneously. This system could support 110 users simultaneously with a permissible bit error rate of 10-9. Power required was lower at the photo detector which means the detection system required less power by applying this code. Direct detection technique used in the ZCC coding system reduced the number of filters, thus led to less system cost. The results showed that employing ZCC coding technique achieved higher bit rates up to 10 Gigabits per second compared to other coding techniques. The principal conclusion was that by the invention of the new ZCC code, it contributed to the solution of many issues in OCDMA such as reduction of MAI, increased the number of users accommodated, increased effective power at the detector, higher bit rates being transmitted, enhanced security and reduced the complexity by using a direct detection technique.
      5  2
  • Publication
    A T-way test suite generation strategy for sequence based interaction testing
    ( 2016)
    Mohd Zamri Zahir Ahmad
    Complementing existing test design techniques (e.g. boundary value analysis, equivalent partitioning and cause and effect graphing), t-way testing is a test design technique that specifically used to cater bugs due to interaction. Many t-way strategies have been proposed in literature including General T-way (GTWay), In Parameter Order General (IPOG), Automatic Efficient Test Generator (AETG), and Jenny for the past 20 years. Although proposed t-way strategies have been proven to detect bugs (in many published case studies demonstrate that the effectiveness of t-way test suite comparable to exhaustive test suite), these strategies only focus on sequence-less interaction. For control and reactive system (i.e. input signals arrived at different time), the implementation of sequence-less t-way strategy is not possible. As a result, researchers nowadays start to focus on sequence based t-way strategy. However, as generating t-way test suite is an NP-Hard problem, no single strategy can claims it producing the optimal test suite for every system configuration. Motivated by the aforementioned challenges, this thesis presented a new t-way strategy, named Sequence Covering Array Test Suite Data Generation (SCATS), which support sequence based tway test suite generation. SCATS implements three main components which is sequence tree, tuple generator and test case generator in order to produe the optimum test suite size. Evaluations have been done by comparing SCATS with existing strategies with various strength( 3 ≤ t ≤ 5) and events ( 3 ≤ s ≤ 30) in term of test suite size generated. Experimental result demonstrates that in most cases SCATS produces competitive test suite size compare to other competing strategies.
  • Publication
    A visual tracking range of motion assessment system for lower limb joint
    ( 2016)
    Lim Chee Chin
    Accurate range of motion (ROM) measurement of lower limb joint motion is important for assessing the severity of human lower limb injuries. It is essential for assisting the medical doctor and physiotherapist to determine the suitable treatment and rehabilitation exercises that are required for lower limb injury patient specifically. Current medical measurement systems such as Universal Goniometer (UGM) has a large resolution of 1° which may cause to have observation error while Electrogoniometer (EGM) is affected by the inaccurate sensor’s position and detachment when moving due to its mechanical properties limitation. Thus, a visual tracking ROM assessment system (VTS) for lower limb joint measurement is proposed. The purpose of this investigation was to develop a method to quantify a ROM of the lower limb joint and examine the ROM obtained between the VTS with EGM and UGM, for the measurement of lower limb joint angles. There were three major experiments conducted i.e., Validation Experiment, Clinical Test and Clinical Case Study. Validation experiment was done on the developed visual tracking system before being applied on the real human subject to ensure the system performance and safety to be acceptable. The system had been tested under the several of light intensity level, camera distance, camera elevation angle and markers location to determine the optimum operating condition. In clinical test, there were two tests carried out; they were Healthy Control Test and Injured Subject Test. A total of 20 healthy control subjects’ findings proved that the left and right lower limbs of human were similar (99.80% ~ 97.64% of similarity) for the normal healthy subjects. Comparison between VTS, EGM and UGM found that the accuracy for each two systems compared to each other was significantly different for the VTS vs. EGM and the EGM vs. UGM. The VTS vs. UGM produced the highest accuracy for all the joint motions compared to VTS vs. EGM and the EGM vs. UGM; it was 99.46% for left knee flexion. In addition, total of 70 injured subjects (included ankle joint, knee joint, and hip joint) had undergone injured subject test to compare its severity level between illness and three measurement systems. In the injured subject test, VTS yielded the smallest coefficient of variation (CV) compared to the EGM and UGM for Knee flexion for moderate injuries which was 2.45%.
  • Publication
    Ambient radio frequency energy harvesting featuring antenna with multistage rectifier
    ( 2018)
    Ismahayati Adam
    The work presented in this thesis focuses on a radio frequency (RF) energy harvesting approach which scavenging energy from RF electromagnetic radiation to generate electrical signal in a real environments. Compared to other alternative energy sources, such as solar and wind, RF energy is the only one that can provide continuous supply of energy regardless days or nights and not affected by bad weather conditions. One of the challenging problems of RF energy harvesting is the low power densities yielded from ambient RF energy. Thus, it is very crucial to design a highly efficient harvester operating at widespread use of RF spectrums. One of the novelty of this thesis is contributes by the investigation of the feasibility of RF energy harvesting in Malaysia, in advance of the harvester design. Through this power density measurements, the scavengeable ambient frequency sources with their associated available RF power level were identified. It is demonstrated that wireless communication systems of GSM 900 (860 – 960 MHz), GSM 1800 (1730 – 1866 MHz) and UMTS (2100 – 2200 MHz) bands provide optimal sources for power harvesting at both measured urban and semi-urban location in Malaysia. The antenna and rectifier circuit are then designed separately prior to their combination and performance assessment. Operated from 1800 MHz up to 2.5 GHz, the proposed RF energy harvester features a broadband antenna and a multistage rectifier in one integrated circuit. Furthermore, the harvester sensitivities are optimized between -30 to -20 dBm, based on the measured available power in the surroundings. The performance of the harvester is investigated by six combination of two rectifiers and three different antennas, tested in both indoor and outdoor environment for dedicated and non-dedicated RF power sources. To further demonstrate the relation between the rectenna polarizations with the capability to harvest the RF energy, a polarization study is conducted. To realize this measurement, a novel simple and broadband circular polarized antenna is proposed. The obtained measurement results are consistent with the power densities measured in power density measurement, where more dc output are obtained in urban areas compared to semi-urban areas. In an urban area, the measurement results indicate the system is capable of harvesting up to 1.8 V dc output from non-dedicated ambient RF energy sources. The dc generated in RF energy harvesting may be less than generated by solar and wind techniques, however it can be significant in the absence of other energy sources.
      1  19
  • Publication
    An efficient modified booth multiplier architecture
    ( 2008)
    Razaidi Hussin
    Multiplier plays an important role in today’s compute intensive applications such as computer graphics and digital signal processing. This thesis described the design of an Efficient Modified Booth Multiplier Architecture. With the tradeoff between speed and area, the design of the Modified Booth Multiplier focused on high speed with a moderate increase in area. This was achieved by reducing the critical path delay in the basic element of the multiplier circuit. Multiplication is performed by generating the partial product of Modified Booth Encoding (MBE) and accumulating the entire partial product by an adder or compressor. The research began by examining the available encoding schemes used to generate the partial product and 4:2 compressor that are used to accumulate the partial product. The fastest MBE and the most efficient 4:2 compressor has been used to develop the multiplier. The multiplier performance was improved by adapting various methods such as Simplified Sign Extension (SSE) and a proper tree topology. The SSE method eliminated some counter or adders in a partial product row while the tree topology arrangement of the compressors and their interconnection accumulate the partial product. A Gajski’s rule had been used to evaluate the performance of the multiplier and the result shows that the new multiplier has reduced delays in producing the output. The new multiplier architecture has reduced delays to almost 2% to 7% compared to other multipliers. The high speed multiplier was then extended to develop a Floating Point (FP) multiplier. The FP multiplier had been successfully designed using Altera Quartus II software and implemented on MAX EPM7182SLC84-7 device. The result showed that the FP multiplier is 38% faster compared to conventional FP multiplier. In term of size, the FP multiplier is 26% bigger than conventional circuit. However the increase in area of the circuit can be tolerated since the aim was to enhance the speed of the FP Multiplier.
      2  5
  • Publication
    An intelligent diagnostic system for malaria
    ( 2015)
    Aimi Salihah Abdul Nasir
    Malaria is a serious health problem, causing many deaths and morbidity cases throughout the world particularly in Africa and south Asia. In 2013, there were about 198 million cases of malaria and an estimation of 584,000 deaths recorded globally, mostly among African children. Malaria is caused by infection of red blood cells with protozoan parasite of the genus Plasmodium. Plasmodium Falciparum and Plasmodium Vivax are the two main species that have caused the most malaria infections worldwide. Malaria can become lifethreatening if it is not treated immediately. Until now, microscopy-based diagnosis still remains the most widely used approaches for malaria diagnosis. However, this subjective evaluation procedure is time consuming, labour intensive and requires special training. Thus, this research has developed an intelligent diagnostic system for malaria which consists of image processing and intelligent classifier for the purpose of malaria diagnosis. A 3-stage classification of intelligent diagnostic system can be used as an early detection for malaria based on the classification of blood samples between normal and malaria on the first stage, and further classify the malaria sample as either P. falciparum or P. vivax species on the second stage, along with its four different life-cycle stages which are young trophozoite, mature trophozoite, schizont and gametocyte on the final stage. In order to perform the diagnosis process, the blood images were processed with various image processing techniques such as contrast enhancement and image segmentation for obtaining a fully segmented malaria parasite. As for contrast enhancement, this study proposed modified global and modified linear contrast stretching based on total pixel approach, as well as modified global and modified linear contrast stretching based on pixel level approach. After the image has been enhanced, the malaria image was segmented using different types of clustering algorithms. This included the used of the proposed enhanced kmeans clustering. The combination between contrast enhancement and image segmentation have provided good segmented malaria parasite. Later, various features such as size, shape and colour based features were extracted from the segmented malaria parasite. These features were fed as inputs to the three different classifiers which are multilayered perceptron (MLP) neural network trained by Levenberg-Marquardt (LM) algorithm, singlehidden layer feed forward neural network (SLFN) trained by online sequential extreme learning machine (OS-ELM) algorithm and random forest. The MLP network trained by LM algorithm has been proven to be the best with the highest classification performance as compared to others. Overall, the intelligent diagnostic system for malaria that has been developed using MLP network trained by LM algorithm is capable to perform the detection process by classifying a total of 1800 images consisting of malaria and normal blood images with testing accuracy, sensitivity and specificity of 95.28%, 96.06% and 86.00%, respectively. As for the diagnosis process, the system has classified a total of 1453 malaria images (accuracy of 90.81%) correctly into P. falciparum and P. vivax species, along with their four life-cycle stages. Thus, the proposed intelligent diagnostic system for malaria parasites is capable to perform the detection of malaria parasites, and then further diagnose the detected malaria parasites into its species and life-cycle stages.
  • Publication
    Analusis of Harumanis mango flowering prediction through biotic and abiotic factors using machine learning
    ( 2018)
    Rohani S Mohamed Farook
    Harumanis Mango (Mangifera indica) is known as one of the best table tropical fruit, due to its aroma and sweetness. Harumanis mango cultivar is included in the national agenda as a specialty fruit from Perlis, Malaysia for the world. Despite its overwhelming local demand in Malaysia and also internationally, the fruit supply never meets the demand. Mango flowering prediction is important as one of the factors to predict mango yield in order to implement effective forward marketing. Forward marketing is a contract that is signed between supplier and client based on the amount of delivery and the price of delivery in future, based on the predicted yield. Harumanis mango is a species that only bear fruit once a year. The biotic and environmental factors are reported in the literature as the factors that influence the mango trees flowering and fruit-bearing. The pre-processing and analysis done shows that the biotic and abiotic factors have non-linear relation with the yield. It is essential to develop, train and test the Harumanis mango tree flowering prediction model through machine learning approaches such as K-Nearest Neighbors (k-NN), Naive Bayes, Support Vector Machine (SVM), Classification Trees (CAT) and Random Forests (RF). Harumanis flowering predictive model on biotic and abiotic factors developed, trained and tested through the data accumulated from Harumanis trees in the greenhouse. The biotic factors are lysimeter, Length of First Whorl (LFW), Length of Second Whorl (LSW), Length of Third Whorl (LTW) and Diameter of the Whorl (DW). The Harumanis flowering prediction on biotic factors indicates that SVM technique prediction accuracy is at 79.9% as compared to k-NN, Naïve Bayes, CAT and RF at 66.5%, 74%. 71.3% and 72%, respectively. The SVM predictive model further tested on several kernels which are linear, polynomial, radial basis and sigmoid. The radial basis kernel accuracy is at 79.9% compared to linear, polynomial, and sigmoid at 65%, 65.7% and 59.8% respectively. The environmental data from Perlis Meteorology Department and the yield from Bukit Bintang Orchard were analyzed to identify the significant abiotic factors in predicting the Harumanis mango yield. Later, the abiotic factors which are average minimum temperature and average soil moisture of the 10 days from Harumanis greenhouse are calculated and utilized in developing the Harumanis flowering predictive model. The Harumanis mango tree flowering prediction on abiotic factors shows that SVM technique is at 90.6% accuracy rate compared to k-NN, Naive Bayes, CAT and RF at 76.6%, 75%, 82.1% and 72% respectively. Concluded that the prediction model using SVM on radial basis kernel through biotic and abiotic factors displays the highest prediction accuracy at 79.9 % and 90.6% accordingly. The SVM with radial basis kernel model able to perform flowering prediction although using a limited data due to the nature of the agricultural domain where the data collection and observation require a longer period of time.
      11  16
  • Publication
    Angle of arrival estimation system for radiation pattern reconfigurable antenna with modified gaussian membership function
    ( 2018)
    Mohd Ilman Jais
    This research focuses on developing angle of arrival (AOA) estimation system (AES) through incoming received signal strength indication (RSSI). Proposed AES is developing on a single board computer (SBC) using an open source GNU Linux operating system (OS). The good AOA estimation systems must able to covered 360° with many estimation points. However, previous AOA estimation systems prototype suffers from a major drawback to achieve 360° angle covered due to limitation of antenna radiation pattern. Therefore, radiation pattern reconfigurable (RPR) antenna operates at 2.45 GHz that capable to cover the wide AOA estimation angle is introduced. Nevertheless, the RPR antenna on AES prototype provides lack of estimation points. Thus, this thesis infuses Fuzzy Inference System (FIS) to further improve decision making and increase the number of AOA estimation points. The FISAES is the first effort in realizing the advantages of FIS with only three sets of RPR antenna abilities without any intelligent algorithm support to cover 360° angle estimation. The FIS-AES algorithm is develop by Python 2.7 programming supported by SciKit library. The proposed Fuzzy Inference System of AOA estimation system (FIS-AES) successfully increases number of estimation from nine to 18 estimation points. Four types of membership function (MF) are trained to obtain response between fuzzifier and defuzzfier of FIS-AES algorithm. A novel MF based Gaussian-MF curve named as the Pattern-MF is introduced. The response between fuzzifier and defuzzfier of FIS-AES algorithm of proposed Pattern-MF approximately ~80% to ~85%, which is the highest compared than existed MF in SciKit library. Moreover, adopted the FIS offers more AOA estimation points, thus it helps FIS-AES capable to improve the absolute error of AOA estimation and root mean square error (RMSE) is ±5° and less than 10 respectively. The investigation of SBC performance is important to verify that SBC competent to act as the main platform of AES. The SBC performance is verified in terms of CPU and memory utilization. In this work, the Raspberry-Pi has successfully completed all tasking with average CPU and average memory utilization less than 10% and less than 31% respectively for S11 measurement and less than 10% and less than 37% respectively for AES measurement. With all capabilities demonstrated and discussed, the FIS-AES have great potential as one of the best options for realizing applications such as localization system man computer interaction.
  • Publication
    Beam-switchable textile antenna for wireless body area networks (WBAN)
    ( 2014)
    Mohd Ilman Jais
    The research work in this dissertation focuses on beam-switchable textile antenna for wireless body area network (WBAN) application. The idea of beam-switchable textile antenna helps to reduce the antenna size and more flexible. Beam-switchable antenna is useful in the rapid growth of the wireless communication system. The advantage of beam-switchable antenna is to avoid the associated signal equalization problems that are incurred as the wearer moves or turns. This dissertation proposed a novel beam-switchable textile antenna (BSTA) with reconfigurable ability which uses Radio Frequency (RF) PIN diodes biasing circuit as the switching mechanism. BSTA is the first effort in realizing a combination of such beam-switching feature onto a wearable radiator by exploiting silver loaded epoxy adhesive to provide a solderless connection between conductive textiles and the RF circuits. Four PIN diode switches are integrated into shieldit super of symmetrical BSTA designed. The BSTA is capable to achieve beam steering ±16° with peak simulated and measured directivities of 6.8 dBi and 6.69 dBi, respectively. The antenna maintains input impedance approximately 50 Ω at 2.45 GHz without the use of additional quarter wavelength transformers. With dimension of 88 x 88 mm2, it is compact enough to be integrated in clothing for WBAN applications. Based on preliminary assessment of specific absorption rate (SAR) results, this research confirms that BSTA is safe to the human being where the simulation SAR result is less than 1.6 W/kg and 2 W/kg for 1g and 10g mass of tissues correspondingly at particular body parts based on ICNIRP regulation. With all capabilities demonstrated and discussed, the BSTA antenna has big potential in realizing a new smart garment antenna.
  • Publication
    Bio-inspired method for improving routing protocol performances in vehicular ad-hoc network
    ( 2017)
    Mohamed Elshaikh Elobaid Said Ahmed
    Vehicular Ad Hoc Networks (VANET) grasp the interest of researchers and many governmental agencies as technological solution for human’s transportation systems. VANET aims at providing connectivity among vehicles on the road and infrastructure network in ad hoc communications scheme. In VANET each vehicle uses a routing mechanism to find a path for sending its messages to the last destination, where messages are sent in a multi hop fashion. The aforementioned behavior emphasis the impact of the routing protocol mechanism in the performances of VANET. In recent years, the analysis of VANET routing protocols and their impact on the performances of network with different network scenarios has significantly developed a better understanding of the requirements and goals for designing a VANET routing protocol. Further, in the literature many routing protocol mechanisms are proposed to deal with VANET’s requirements. Nonetheless, proposed routing mechanisms in the literature considered a single network scenario in VANET. However, Vehicles or moving nodes in VANETs are tend to travel in long distances, which implies their engagement in multiple network scenarios and topologies. The adhered behavior of VANET’s nodes results in a need for a routing mechanism that addresses the requirement of more than one network scenarios and topologies. This problem is less considered in the literature. Hence, this thesis proposes a chameleon method routing mechanism to tackle the dynamic topology changes in VANET. The proposed mechanism defines the performances of a routing protocol in different network scenarios as a single and multiple objectives optimization problem. Taguchi Method and differential evolution optimization methods are used to solve the routing parameters optimization problem.
      2  6
  • Publication
    Broadly steerable parasitic patch array antennas using PIN diode switches at 5.8 GHz
    ( 2014)
    Thennarasan Sabapathy
    The work described in this thesis aimed to design radiation pattern reconfigurable (RPR) antenna that is capable to combat propagation scenarios such as fading, interference and shadowing with its ability to steer the beam towards a desired direction. Patch type RPR antennas suffer from major drawback of achieving beam tilt angle with respect to broadside due the finite ground plane behind the radiating element. The maximum tilt angle achieved is 30° by the existing patch RPR antennas without the implementation of actual RF switches. In this thesis, thorough investigation on parasitic patch array antenna with actual RF switches is conducted with two types of RF PIN diodes, namely BAR50-02V and HPND-4005. Taconic substrate is chosen to design the antennas since it offers low tangent loss. The mutual coupling and Yagi-Uda principles are adopted to design the three-element parasitic patch array antenna with the two types of RF PIN diodes. BAR50-02V is adopted to design Low Isolation Loss Parasitic Patch Array Antenna (LILPPA). A novel installation of RF PIN diodes in patch antenna is introduced, where the BAR50-02V diodes are embedded inside the substrate of the antenna. Due to low isolation loss (ISO), LILPPA with BAR50-02V PIN diode only achieves maximum tilt angle of 23°. HPND-4005 PIN diode is adopted for the design of High Isolation Loss Parasitic Patch Array Antenna (HILPPA). HPND-4005 PIN diode offers high ISO at 5.8 GHz frequency, thus it helps HILPPA to achieve maximum tilt angle of 30°. In both designs, only four RF PIN diodes are used. Next, Broadly Steerable Parasitic Patch Array (BSPPA) antenna is proposed and it uses HPND-4005 PIN diode, since the diode yields superior performance with HILPPA antenna in terms of beam tilt angle. BSPPA antenna able to improve the beam tilt angle to 50° by adopting techniques of adding parasitic element, increasing the number of switches and reducing the ground plane with respect to the broadside. BSPPA antenna is able to work in two modes where in the first mode it is capable of steering the directive beam patterns towards five directions, -50°, -30°, 0°, +30°, +50° in H-plane. In the latter mode, BSPPA is able to shape the beam pattern from narrow beam to broadside beam. HPND-4005 PIN diodes require high reverse bias voltage at OFF state. The problem arises if the antenna is connected to the I/O ports of control devices such as microcontroller or microprocessor since they operate at 5V and 0V for High and Low operation. To solve this, an exclusive electronic switching network is developed to perform the switching of HPND-4005 PIN diodes. All three antennas developed in this work have high gain of greater than 6 dBi and common operational bandwidth of greater than 100 MHz. With this characteristics, the proposed antenna could be a promising candidate in latest wireless communication system such as WIFI and WiMAX.
  • Publication
    Classification of binary insect images using fuzzy and gaussian artmap neural networks
    ( 2006)
    Shahrul Nizam Yaakob
    Object recognition and classification is an essential routine in our daily lives. Our eyes act as a camera capturing the image of particular object and sending it to the brain to be recognized. Thus, the eye vision system inspires researchers to create machine vision systems. As a significant part of the machine vision system, this research focused on two (2) important phases of the system; feature extraction and classification. As for the feature extraction six (6) different types of moment invariant techniques namely Geometric moment invariant (GMI), United moment invariant (UMI), Zernike moment invariant (ZMI), Legendre moment invariant (LMI), Tchebichefmoment invariant (I'MI) and Krawtchouk moment invariant (KMI) are used to extract the global shape features of the binary insect images. These features are then channeled to the Fuzzy ARTMAP (FAM) and Gaussian ARTMAP( GAM )neural network to be classified and recognized. In the GAM neural network, a gamma threshold is proposed to find the optimal value for gamma parameter acting as the initial value for a Gaussian distribution in the training phase. It is found that KMI is the best technique for features extraction of the global shape information of the insect images as compared to GMI, UM!, ZM!, LMI and TMI. The finding is based on the lowest value of Total Min Absolute Error (I'PMAE) (0.03%-1.01). The training and testing method for both neural networks is based on 4- folds cross validation technique. It is also found that the performance of F AM neural network is influenced by the types of normalization technique utilized. The Improved Linear Scaling (ILS) normalization technique generated the highest classification rate by the F AM neural network when compared to Unit Range (UR) and Improved Unit Range (IUR). It is further found that GAM neural network is a better insect classification technique when compared to F AM neural network producing the classification accuracy up to 99.58% whereby the classification accuracy of FAM neural network is 82%.
  • Publication
    Classification of fish images based on shape characteristic
    ( 2015)
    Mohd Wafi Nasrudin
    This research work has been conducted to analyze and classify the types of fish image based on shape characteristic. The features of characteristic of fish image are extracted by using three Moment Invariants (MI) techniques and Fourier descriptors (FD). The types of Moment invariants are Geometric moment invariant (GMI), United moment invariant (UMI), Zernike moment invariant (ZMI). In the FD’s technique, there are two edge detection have been used to create the boundary of the image, namely Robert cross detection and Sobel cross detection. These feature extraction techniques have been used to analyze the image due to its invariant features of an image based on translation, scaling factor and rotation. There are two ways to examine the performance of feature extraction techniques, namely intra-class analysis and classification analysis. For the intra-class analysis, a set of equations has been implemented to find the best technique among the three different types of moments and Fourier descriptors based on the low value of Total Percentage Min Absolute Error (TPMAE). Meanwhile, for the classification analysis, the Artificial Neural Network (ANN) is explored and adapted to classify the fish images. The feature vectors produce by feature extraction techniques that represent the image are used as the input of classification. The results of the intraclass analysis indicate that the UMI was the best technique among the moment techniques while Fourier descriptor by using the Sobel edge detection shows the lower TPMAE as compared to Robert edge detection. For the classification part, two types of ANN’s which are Multilayer Perceptron (MLP) and Simplified Fuzzy ARTMAP (SFAM) neural networks have been used to classify the image based on fish category. The Leverberg-Marquardt (LM) algorithm is used to train the MLP network in order to check the applicability. Based on the classification that has been computed, the results show that all networks perform good classification performance with overall accuracy is around 90%. However, the MLP trained by Leverberg-Marquardt shows the highest classification performance in classifying the fish images as compared to the SFAM network.
  • Publication
    Classification of human breathing activity based on Electromyography signal of respiratory muscles
    ( 2020)
    Ahmad Nasrul Norali
    Electromyography (EMG) signal based pattern recognition have been applied for various applications especially in Human-Machine Interface (HMI). Most of previous research works focused on human muscles which related to movements of arms and fingers for controlling body parts through intention. Statistical analysis has been used in most research works on muscle assessment and performance measurement. There are only few literatures on EMG pattern recognition study that used other than arms or hands. Ths thesis will focus on the use of EMG pattern recognition to classify the human breathing task. Four respiratory muscles have been chosen for EMG data acquisition i.e. sternocleidomastoid, scalene, external intercostal and diaphragm. The selected human subjects are used to perform four breathing tasks which are quiet, deep, deep & hold and fast breathing. The feature extraction of EMG consists of basic features and its convolution. The basic features are Root Mean Square (RMS), Zero Crossing (ZC), Mean Frequency (MF) and Mean Power (MP). The convolution is performed between pairs of the bsic features. The EMG pattern recognition is performed by using K-Nearest Neighbor (K-NN), Multilayer Perceptron Artificial Neural Network (MLP-ANN) and Support Vector Machine (SVM). Segmentation window size is configured at 1000 ms. Results showed highest accuracy of 96.86% on convolution of RMS and MF features using SVM classifier. The convolution feature extraction will enhance the EMG classification accuracy for human breathing compare to basic features of time and frequency domain. Study on classification of human breathing activity based on EMG of respiratory muscles can be implemented in biofeedback rehabilitation. The EMG from respiratory muscles can be used in physical therapy for disabled person by controlling an assistive device such as robotic limb and electric wheelchair.
      10  1
  • Publication
    Core nucleus polarization in lambda (۸) hypernuclei
    ( 2012)
    Zaliman Sauli
    The response of the core nucleus to the L in a hypernucleus is studied with a local density approximation. This reproduces the energies and radii of the core nuclei as well as the L-single particle (s.p.) energies quite well. The polarizing effect of the L depends on the core response through an “effective” compression modulus KA of the nucleus. For certain class of energy functional, KA is found to be almost independent of the compression modulus K of the infinite nuclear matter. This indeed is a surprising result, and at variance with the Hartree-Fock calculations with effective interactions. Reasons for this discrepancy were carefully examined, by considering values of K in the range 100-400 MeV. Furthermore, the polarizing effects also depend critically on D(r), the L binding in nuclear matter at density r. For only a direct LN force: D µr and the core nucleus contracts giving rise to a relatively larger core polarization. However, for a “saturating” D(r) (with a maximum at rm < r0, where r0 is the nuclear matter equilibrium density), which is required to fit the s.p. data, the s-Shell hypernuclei binding energies and the low energy Lp scattering data, and which results from a LN force (including exchange) and LNN forces, there may be an expansion of the nucleus with nucleons flowing from the interior to the surface. This is shown to reduce the core polarization effects substantially (for rm in the neighborhood of r0). The resulting changes in root mean square radius and core energy depend on A, but are mostly very small, justifying their general neglect. The present work thus demonstrates that L can be used as a reliable tool to probe the properties of nuclei.
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  • Publication
    Database encryption for a web-based claims system
    ( 2007)
    Syed Zulkarnain Syed Idrus
    The main purpose of this study is to develop a computer system for UniMAP staff to make claims via electronic media. The system development is based on the Treasury Circulars by the Ministry of Finance, Malaysia as well as other circulars related to it. Other important particulars had been built into the system such as salary, grade, entitlement and others. Another additional feature included is the automatic calculations. This system can also be equipped with a security tool to prevent hackers or unauthorised persons, which can be selected from the results of the security analysis. There are three categories of user involved in the development of the system. They are the Claimant, Responsibility Centre and Bursary Department. The Responsibility Centre consists of all administrative departments as well as centres of study from where the budget allocation is acquired. The development of the system begins by designing of the Process Flow Diagrams showing the steps or procedures that need to be followed in sequence respectively. All the three categories of users must follow their flow of the diagrams. Process flow is a flow that determines the movements of the forms from the moment they are submitted up to the stage where payments will be made. This process is to be followed by the designing the Data Flow Diagram and then the Database. The former specifies how the data will flow in the system, whereas the latter is for data storage where all data are kept such as login identifications, passwords, staff personal particulars, entitlements etc. The development of the Database comes in four forms namely Entity-Relationship Diagram, Hierarchical Diagram, Relational Database Diagram and Data Dictionary. Out of twenty encryption algorithms that are available in the Dynamic-Link Library (DLL), only five have been selected to go through and perform analysis for comparison in terms of its performance and compatibility with the developed system. Since this system is Web-based, staff can make claims anywhere, anytime and at any locations. This method can overcome not only human errors but also more efficient, fast and accurate. Therefore, this system can also save time, effort, and administrative costs. In this study, Active Server Pages (ASP) has been chosen to make the calculation and also to generate reports. After the system has been developed, a test was conducted using forms that have been simulated manually. The purpose is to enable the researcher to make comparison with the ones made using the developed system in order to detect errors or flaws from the manual simulation in the system. Testing was also done on the encryption algorithms and Web browsers selected by increasing both the text length size and key length size and observed its performances. Having noted its response times, an analysis was made in order to determine which encryption algorithms’ and Web browsers’ performances were most suited for the developed system and considered the best, which is lower and able to sustain its response times. The results of this study have shown that this system is able to detect all human errors in the traditional manual claim system, in which claimants have made some mistakes. On the other hand, the analysis of encryption algorithms with Web browsers, the results have shown that Twofish algorithm is best suited to the system that has been developed using ASP Web programming language on Internet Explorer. Hence, it is emphatic that all objectives that had been set at the beginning of this research have been met.
  • Publication
    Design and analysis of 90 nm two-stage operational amplifier using floating-gate MOSFET
    ( 2017)
    Faradilla Aziz
    Low voltage, low power dissipation, high gain and matching are some of the concern when designing an analog circuit. A very low voltage can increase battery lifetime and integration density as market demands. Floating-gate Metal-Oxide-Semiconductor (MOS) also known as FGMOS is a new technology design that has been introduced as an element in low voltage circuit design in CMOS technology. FGMOS technique has been reported as low voltage and low power design application for increasing the battery lifetime due to its lower threshold voltage. The operational time of the FGMOS transistor can be improved by controlling the threshold voltage without reducing the feature size of the transistor. This research focuses on analyzing and comparing the simulation application of FGMOS technique with conventional MOSFET for various circuit designs. Capacitor ratio of 0.5 with value of 2 fF of the FGMOS transistor is chosen in order to have most stable output result. Proposed FGMOS operational amplifier circuit consists of two stages namely input differential circuit and output buffer stage that contributes in amplifying an input signal. The circuit simulations are analyzed using Full Custom Synopsys software with 90 nm CMOS technology. The simulated results show approximately 42 dB of gain with 3dBbandwidth of 233 kHz, unity gain bandwidth of 23.6 MHz and total power dissipation of 203.3520 mW. In conclusion, the proposed FGMOS designs show comparable result with conventional MOSFET designs. However, the proposed design performance can be improved in further research due to its lower threshold voltage.
      2  11
  • Publication
    Design and characterization of self-switching diode and planar barrier diode as high-frequency rectifiers
    ( 2018)
    Zarimawaty Zailan
    The development of high-speed rectifying devices has become one of major research areas which can be utilized in many applications, including radio-frequency (RF) and detection systems. Examples of these devices are Schottky diode and planar-doped barrier diode. However, all these excellent devices require a very challenging in fabrication process due to their complex structures and a precise doping concentration for each critical layers which are relatively high cost. The prospects of using electronic devices with planar structure are therefore become increasingly promising. These planar devices provide additional advantages of being not only simple but also able to operate at high frequencies. As such, in this research work, the feasibility of utilizing two silicon-based planar nanodevices of self-switching diode (SSD) and planar barrier diode (PBD) for microwave and terahertz rectification has been demonstrated using simulations. SSD has recently been demonstrated as room-temperature rectifiers operating at terahertz frequencies. In this research work, the rectifying performance of SSD is evaluated using a parameter known as the curvature coefficient, derived from the current-voltage (I-V) characteristic of the device. The effects of varying the geometrical structure and the insulator dielectric relative permittivity (from 1 – 9.3) of SSD on the curvature coefficient of the device are studied and analyzed by means of a two-dimensional device simulator. The simulations are also performed under temperature range of 250 – 500 K. The results show that the highest cut-off frequency attained in this research work is approximately 19 GHz, operating at unbiased condition. By implementing similar simulation settings used in demonstrating siliconbased SSDs, a new unipolar planar nanodiode as a rectifier is introduced and developed in this research work. This new device is referred as PBD which has a funnel-shaped geometrical channel that allows current to flow across the device. At zero bias, the nonuniform depletion region, developed at the neck of the funnel-shape channel due to surface charges at semiconductor/insulator interface, is predicted to create an energy barrier along the channel with asymmetrical profile. An external voltage applied across a PBD is expected to produce different height of the energy barrier depending either the voltage given is positive or negative. As a result, a nonlinear I-V characteristic is realized which can be utilized in signal rectification. This operating principle of PBD has been demonstrated and validated in the simulations of this research work. It has also been described using thermionic emission theory which may govern the flow of current across the device. Similar to SSD, the rectification performance of PBD is characterized and evaluated based on the curvature coefficient and cut-off frequency of the device. By varying the geometrical design and insulator dielectric relative permittivity (from 1-9.3) of PBD, curvature coefficient of the device can be optimized in order to improve the rectification performance. The highest cut-off frequency obtained in the simulation of this work is approximately 0.8 THz. Both SSD and PBD have a planar architecture that can therefore be realized in a single lithography step which makes the whole fabrication process of the devices simpler, faster and at lower cost when compared with other conventional electronic devices.
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