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Amplification and generation of short and ultrashort pulse from hafnium bismuth erbium co-doped fiber / Aminah Ahmad
No full textCompact optical amplifier, nonlinear fiber laser and pulse generation have been successfully demonstrated using hafnium-bismuth-erbium co-doped fiber (HB-EDF) as the gain medium. The HB-EDF was recently fabricated using a modified chemical vapour deposition (MCVD) process in conjunction with the solution doping (SD) technique. The fiber has an Erbium ions concentration of 12500 wt. ppm, which was realized due to the co-doping with Hafnium and Aluminum ions. Firstly, a flat gain amplifier operating was realized using 50 cm long HB-EDF at -10 dBm input signal. The amplifier’s gain varies from 9.3 to 9.8 dB with a noise figure less than 4.1 dB within a wavelength range from 1525 to 1555 nm. A BFL can be realized with 0.5 m long HB-EDF to generate a stable Stokes operating at wavelength 0.09 nm shifted from the Brillouin pump. Multiwavelength fiber laser combs have been successfully achieved by the deployment of an HB-EDF as a gain medium at room temperature. For instance, a Brillouin Erbium fiber laser with an eight-line comb with an average spacing of 0.087 nm was obtained at the 980 nm pump power of 75.3 mW. The multi-wavelength comb with a constant spacing of approximately 0.26 nm was also realized by making use of the four-wave mixing
effect. Q-switched and mode-locked HB-EDFLs have also been successfully demonstrated using two different SAs: multi-layer BP and Bismuth-doped fiber. For instance, a stable Q-switched HB-EDFL was obtained with a triple wavelength operation using a backward pumping scheme in conjunction with BP SA. The stable multiwavelength optical pulses are achieved with repetition rates of 41.15- 60.83 kHz by adjusting pump power. The shortest pulse width of 6.06 μs and the maximum pulse
energy of 12 nJ were obtained at 223 mW pump power. A dark pulse generation was also successfully demonstrated through a mode-locking operation in a fiber laser cavity with BDF as a SA and HB-EDF as a gain medium. The mode-locked operational wavelength was recorded to be 1531.95 nm, with the repetition rate of 1.1 MHz. The proposed fiber lasers a compact design since they used an ultra-short length of HB-EDF as the gain
medium
Development of fluorescent and colorimetric rhodamine chemosensors for selected metal ions / Cheah Poh Wei
No full textMetal pollution as a result of industrialisation has been a recurring environmental issue for humans and aquatic ecosystem. However, conventional methods used to detect these metals are deemed inconvenient and impractical for on-site sensing, hence an alternative method is highly sought after. Thus far, rhodamine based probes have shown encouraging results in this area but limitations such as low sensitivity and interference from other metal ions still persist. Therefore, in an effort to improve the efficacy of metal detection, four rhodamine Schiff base chemosensors were synthesized from the condensation of rhodamine B hydrazide with different ketone and aldehydes, namely 2,4,6-trihydroxybenzaldehyde, 3-hydroxy-4-methoxybenzaldehyde, 6-bromoveratraldehyde, and methyl ethyl ketone to form sensors THB, HMB, BVT, and MEK respectively. Characterization of the chemosensors were carried out with FTIR, 1H-NMR, 13C-NMR, and X-ray crystallography. The selectivity, sensitivity, and specificity of each sensor towards various metal ions were studied with UV-vis and fluorescence spectroscopy. Results obtained have revealed different metal preferences of each sensor through colour changes, enhanced absorbance, and fluorescence, whereby BVT, HMB, and MEK were selective towards Al3+ and Sn2+ ions, while THB was shown to be selective towards Cu2+ ions. The detection limits of these sensors were also evaluated and compared with WHO acceptable limit of Al3+, Cu2+, and Sn2+ in drinking water. Among the sensors synthesized, THB displayed the lowest limit of detection for Cu2+ (0.48 M) followed by MEK, HMB, and lastly BVT towards their respective target metal ion. Additionally, the formation of the sensor-metal complex was confirmed to be reversible through the utilization of EDTA, with MEK having the highest reproducibility (up to 6 cycles) amongst the four. While the binding stoichiometry determined through Job’s plot was different for each sensor, the most probable binding site involves the amide carbonyl of rhodamine spirolactam ring, as revealed by the shifting of this characteristic peak to a lower frequency in the sensor-metal complex FTIR spectra. Then, the concept of these four Schiff base ligands as an on-site sensor that provides ‘naked-eye’ recognition of Al3+, Cu2+, and Sn2+ in 100% aqueous condition was also effectively developed with paper test strips. Furthermore, the potential of these Schiff base ligands as cancer inhibitory agents were studied using colorectal adenocarcinoma cell line (HT-29) and non-cancerous colon cell line (CCD-18Co) via MTT assay. Both BVT and HMB were not cytotoxic towards cancerous HT-29 cells, but MEK exhibited comparable cytotoxicity with cisplatin and THB was weakly cytotoxic. Nonetheless, we have successfully synthesized four new rhodamine Schiff base ligands that provides rapid “naked-eye” detection through off-on colour changes in this study. The convenience, portability, and facile synthesis of these ligands further suggest its potential application as an on-site testing kit for the detection of Al3+, Cu2+ and Sn2+
Genetic studies on familial genetic generalized epilepsy: A whole exome sequencing approach / Chan Chung Kin
No full textGenetic generalized epilepsy (GGE) is a form of epilepsy that is potentially caused by genetic factors. It accounts for 15-20% of all epilepsy worldwide and 18.7% of the epilepsy cases in Malaysia. Unlike focal epilepsy, patients with generalized epilepsy mainly rely on antiepileptic drugs to achieve seizure control. As a result, understanding of the molecular pathway behind generalized epilepsy would be beneficial as it can aid the treatment decision and the design of newer antiepileptic drugs. The pathway analyses in GGE were conducted on European population and these results may not be applied to Malaysian or Asian due to genetic variation. Hence, this project was conducted to identify the genetic factors and plausible biological processes associated with GGE in Malaysia. The project started with whole exome sequencing on 12 unrelated Malaysian probands (4 Malays, 3 Chinese and 5 Indians) and 2 unrelated Malaysian Chinese proband-parent trios, all the 14 probands were diagnosed with GGE and having family history of epilepsy. The exome sequencing data was then analysed with GATK and the variants were annotated with wANNOVAR. Following variant filtration, a 3-step functional characterization analysis encompassing gene prioritization, protein-protein interaction analysis and DAVID enrichment was conducted. The analysis found the GO terms related with sodium and calcium ion transport, such as GO:0035725, GO:0006814, GO:0070588 and GO:0070509, were highly associated with GGE among Malaysians. The active role of ion channels in epilepsy makes them an ideal therapeutic target for antiepileptic drugs in seizure suppression. From this prospective, the protein-protein interaction analysis has suggested the potential of dystrophin (DMD) to be used as therapeutic target due to its regulatory role on sodium transporters and calcium ion channels. Besides, the functional characterization analysis has also intimated the potential risk of tyrosine kinases NTRK1, NTRK2 and ERBB4 in the pathogenesis of GGE. Additionally, segregation analysis was conducted on 2 families to study the pathogenicity of the SCN1A c.5753C>T and ERBB4 c.1972A>T variants identified from this cohort. The results showed that the SCN1A variant was likely pathogenic but the ERBB4 variant was expected to induce epilepsy via an interaction with gamma-aminobutyric acid type A (GABA-A) receptor gene GABRA1 c.448G>A variant. A disease model illustrating the combined effect between the mutant ERBB4 and GABRA1 in GGE pathogenesis was proposed, this hypothesized disease model may provide a new insight on the impact of ERBB4 in the disturbance of inhibitory postsynaptic current (iPSC) and excitation-inhibition (E/I) balance. While this project is just a preliminary study on the genetics behind GGE among Malaysians, this study has demonstrated that ion channels are not the only cause of GGE, tyrosine kinases may also contribute to GGE by manipulating numerous biological pathways like the expression of GABA-A receptors. Moreover, the identification of DMD as a potential therapeutic target warrants further investigation as the findings may contribute to the design of new antiepileptic drugs in future
Alkalinity of cement mortar containing different types of supplementary cementitious materials under accelerated curing conditions / Sumra Yousuf
No full textCement-based materials (CBMs) such as paste, mortar and concrete are the most dominant construction materials of structures. They are highly alkaline, with a pH in the range of 12.0 to 13.5, due to Ca(OH)2 contents (portlandite). The strength-gaining rate and hardening process of CBMs under normal curing conditions are slow. Therefore, accelerated curing methods are applied for gaining high early-age strength, especially in prefabrication industry. The CBMs subjected to an initial high curing temperature undergo accelerated hydration resulting in non-uniform scattering of hydration products. It creates a high porosity and reduction in compressive strength at later ages, called the phenomenon of crossover effect (COE). On the other hand, there is this belief that using supplementary cementitious materials (SCMs) in CBMs reduces Ca(OH)2 contents in the process of formation of secondary gel, resulting reduction of pH value. As the pH value and COE affecting both mechanical and durability properties of CBMs, therefore, the pH and COE of pure and blended CBMs under different curing conditions and for short and long terms should be studied. The main objective of this research is to study the short and long-term pH values of cement mortar incorporating various types of SCMs in low and high volumes under normal and accelerated curing methods. For monitoring the COE phenomenon, the compressive strength of mortar samples was measured in short and long terms. For measuring the pH value, the inner portion of samples was taken and grinded using grinding machine. The prepared powder was mixed with water in dilution ratio of 1:2 to make the solution and then the pH readings were taken by digital pH meter. The thermal gravimetric analysis (TGA) test was used to determine Ca(OH)2 contents for the mortars. In addition, measurements were conducted for the specimens after exposure to high temperatures of 200, 400, 600 and 800 ℃. The results showed that COE was observed in OPC control and blended cement mortars incorporating FA, GGBFS, ground and treated palm oil fuel ash (G-POFA and T-POFA)) from 56-150 days. However, it was less than 10% for all types of these mortars. The pH of blended cement mortars was less than the control OPC mortar at the same age and curing conditions. A decreasing trend was found for the pH of almost all the cement mortars with curing age up to 150 days. It was observed that different curing conditions has no significant effect on the pH of cement mortars at the same curing age. Results confirmed that the pH of CBMs does not remain constant with ageing. There was a decreasing trend in pH and Ca(OH)2 contents by increasing replacement volumes of SCMs with OPC in the blended cement mortars. In addition, from the TGA test result, it was confirmed that the pH of CBMs is not only dependent on the Ca(OH)2 content and other factors must be investigated
Improving robot Darwinian particle swarm optimization using quantum-behaved swarm theory for robot exploration and communication / Duaa Mehiar
No full textDespite the significance of the Robotic Darwinian Particle Swarm Optimization (RDPSO) algorithm on swarm-robot exploration and communication, there remain notable gaps such as premature and slow convergence, collisions between robots, and communication breaks and constraints. The quantum computing theory has several advantages that can improve the searching capabilities of PSO-based algorithms. However, there has yet an attempt to adopt quantum behaviour onto robot-based system such as the RDPSO. In this study, a new algorithm called the Quantum Robot Darwinian Particle Swarm Optimization (QRDPSO) is contributed with the hypothesis that quantum behaving particles can address the RDPSO main gaps; i.e. to improve the exploration and communication performance of a swarm robotic system. In terms of convergence time, the experiment done shows the QRDPSO algorithm is faster to reach an optimal solution than the RDPSO algorithm. The QRDPSO algorithm also shows tolerance to premature convergence compared to RDPSO. This study also contributed a distributed swarm navigation strategy that allows the QRDPSO robots to communicate directly with other robots in the swarm. Two popular communication schemas over wireless sensor network have been adopted and tested on the QRDPSO, the Multi-hop Routing Algorithm with Low Energy Adaptive Clustering Hierarchy (MR-LEACH) and the mobile ad hoc communication network (MANET). The QRDPSO algorithm with MR-LEACH consumes less power with energy consumption at 48% compared to the QRDPSO with MANET at 63%. Less power allows the MR-LEACH to increase lifetime for the nodes more than MANET while reducing interruptions between robots but not faster to reach the optimal solution than the QRDPSO algorithm with MANET. The QRDPSO with MANET needs 180 iterations, while the QRDPSO with MR-LEACH needs 202 iterations. The predecessor, RDPSO, needs 210 iterations for comparison to reach a victim. Given the importance of a swarm’s sustainability; swarm not losing robots, able to conserve energy and explore farther, the MR-LEACH schema is proposed to complement the QRDPSO communication
Adaptive global reasoning with multiple knowledge graphs for object detection / Tao Bo
No full textThe dominant object detection system's mechanism is to propose some regions of interest and then classify them and locate these regions with bounding boxes. In other words, the current object detection system is modeled as classification on boxes in parallel without considering the relationship between the objects. Such strong semantic information should be used to help current object detection systems to get more accurate results. In contrast, human vision recognition system can recognize objects easily, even in very complex scenes (heavy occlusion, more categories, class ambiguities, etc.). The main reason is that humans have the knowledge (common sense) to help them recognize what they see. When humans cannot see the target object clearly, the visual reasoning process goes on: With the help of surrounding objects and environment or context, humans usually have the ability to deduce the object. Inspired by the human visual recognition mechanism, many works have been done to incorporate knowledge base to current object detection system to imitate the reasoning process. The dominant reasoning process is to propagate region features through a fixed external knowledge graph. The nodes in the graph represent region proposals, and edges represent connections or relationships of each pair of nodes. After the learning process through the knowledge graph, the region proposal
Fatigue predictive model for mid-air gesture interaction / Md Ibnul Adib
No full textGesture interaction in HCI has been one of the most important evaluation. For mid-air gesture interaction, the user moves their hand in different directions to imitate signals that the machine can understand. These hand gestures were borrowed from different sign languages. Studies performed on sign language interpreters show that most of the sign language interpreters face different kinds of fatigue or mild to serious kind of physical disorder which is an alarming phenomenon for the computer science industry. The objective of the present research is to identify the existing hand gesture signals in HCI application areas and find the fatigue criteria for these hand gesture signals. Based on the fatigue criteria a Fatigue Predictive Model has been proposed, based on a preliminary study done using the Cogulator tool. Then a prototype which can analyze fatigue in mid-air gesture interaction was designed, developed, and evaluated. A quantitative study of the prototype was conducted with 60 participants. From 29 mid-air hand gesture signals participants felt discomfort and muscle tension in 7 hand gesture interactions. These 7 gestures are separated into two categories based on their gesture design pattern. These gestures were unique in design, involved extensive muscle usage and had to repeat the gestures to avoid false tracking. This study proposes a predictive model to find out the gestures which have higher possibilities to cause fatigue among users based on the data found from fatigue criteria which will help HCI industry or manufacturers to choose the gestures according to the convenience to the users who will be conducting the gestures
Data embedding using predictive syntax elements in scalable coded video / Pang Lie Lin
No full textWith the rapid advancement in digital technologies, video has emerged as one of the most effective and popular communication media. While videos are increasingly adopted for various purposes including entertainment, dashboard camera recording, and recently education, many issues related to video arise, including unauthorized or illegal use of video content, tampered video content, and packet loss due to network congestion or bandwidth fluctuation. As a result, various proposals are put forward to manage videos, and one of them is data embedding. Essentially, data embedding inserts data into a video to serve a specific purpose, including proof of ownership via watermark, covert communication in steganography, as well as error concealment and authentication via fragile watermark. This work focuses on embedding data into video coded in the format of Scalable High Efficiency Video Coding (SHVC), which plays an important role in adaptive video streaming applications. The scalability feature is essential, notably when considering the heterogeneity in transmission and decoding devices. However, the underlying architecture of this scalable video coding standard differs from the previous scalable video coding standards. A study is therefore required to explore the possibility to embed data into SHVC encoded video. Specifically, the predictive syntax elements in the SHVC compressed domain are analyzed. To increase embedding capacity, payload bits are embedded in all scalable coded layers. Conceptually, coding a video frame using more (smaller) prediction blocks leads to more embedding opportunities due to the availability of the syntax elements. Therefore, an adjustable control parameter is introduced to guide the quad-tree partitioning process to permit more split blocks. The proposed technique achieves encouraging payload with slight bit rate overhead. When a predictive syntax element is utilized for data embedding, the encoder calculates and encodes the prediction error caused by data embedding as a portion of the prediction residual and reconstruct the video as similar as possible to the original video. Hence, the manipulation of predictive syntax elements will not cause drift-error. In view of this, both intra- and inter-coded blocks are jointly utilized for data embedding without compromising the perceptual quality. During encoding, the prediction modes and partitioning depth are assessed by rate distortion optimizer, and only the one with the best rate distortion cost is adopted for coding. A data embedding framework named CUPSEED, which automatically selects different prediction elements for data embedding, is then proposed to manage multiple data embedding venues and coding layers. The proposed framework outperforms existing data embedding techniques in the SHVC compressed domain in term of embedding capacity. It manages to achieve higher payload while preserving the perceptual quality with minimal bit rate variation
Hak-hak tetamu dalam Islam: Kajian terhadap kemudahan hotel mesra muslim terpilih / Syed Muhammad Zaim Syed Mohd Zaki
No full textMinat masyarakat terhadap pelancongan Islam telah meningkatkan pendapatan sektor ini.
Malaysia telah menarik pelancong melalui pakej pelancongan Islam, dengan menawarkan
pelbagai aspek penginapan, terutama yang berkaitan dengan kemudahan mesra Muslim
untuk memenuhi hak-hak tetamu. Namun, dikatakan bahawa kemudahan yang disediakan
oleh pengusaha hotel mesra Muslim masih belum memuaskan dalam menunaikan hak
tetamu. Oleh itu, kajian ini dilakukan untuk melihat kemudahan yang terdapat di enam
hotel mesra Muslim terpilih yang dimiliki oleh Majlis Agama Islam Negeri dan untuk
mengesahkan usaha hotel dalam memenuhi hak tetamu. Proses pengumpulan data
menggabungkan kaedah pemerhatian dan temu bual. Hasil kajian menunjukkan bahawa
tahap ketersediaan kemudahan berdasarkan hak tetamu di hotel mesra Muslim adalah
memuaskan dengan ketersediaan melebihi 70%. Di samping itu, hasil kajian juga
mendapati bahawa hotel-hotel tersebut telah memenuhi hampir semua hak-hak tetamu
seperti yang digariskan dalam Islam. Walau bagaimanapun, masih terdapat beberapa
ruang penambahbaikan yang harus dipertimbang untuk mengukuhkan amalan sedia ada
demi keselesaan tetamu pada masa hadapan
The art of Shia Yih Yiing: Problematizing Malaysian multiculturalism / Tan Kim
No full text"Malaysia, TrulyAsia" is the popular slogan used when it comes to promoting Malaysia as a tourist spot. We could see the descriptionofMalaysia overall as a country on the official tourism website,“ There is only one place where all the colours, flavours, sounds and sights of Asia come together–Malaysia.", multiculturalism is one of the keyselling points of Malaysia.Most often the media represent happy Malaysian multiculturalism, by focusing on the diverse cultures,the exotic traditions of multiple cultural identities, and how these cultural identities coexist together. However, as suggested by many scholars, the idea of multiculturalism is not at all unproblematic. In a glance, Shia Yih Yiing's artworks fit perfectly in to the government narrative of happy multiculturalism, there presentation of multiplecultural identities, coexisting in a harmonious setting. Nonetheless, through the reading of secondary resources as well as personal interviews with Shia Yih Yiing, she mentioned her attempt of incorporating poeticresistancestrategiesinherartwork,revealingherintentwasnottosimplyshowhappyMalaysian multiculturalism.Therefore,thisresearchattemptstoanalysesfurtherontherepresentationofthemultipleculturalidentitiesofMalaysia,withaspecialfocusonfairytaleasherpoeticresistance strategy, how she chosetorep resentthese Malaysian identitieswithspecificfairytalecharacter. An attempt will alsobemadetoproblematize Malaysian multiculturalismthrough the discussion of Malaysianmulticulturalism situation visa vis the specific choice of fairy tale charactersshehasusedtorepresentacertain cultural identity, as well as the in clusion and exclusion of a certain cultural identities in the representation