This study discusses the evaluation of oscillatory stability based on the synchronizing K s and damping K d torque coefficients for a single-machine system connected to an infinite bus (SMIB). ...Particle swarm optimization (PSO) technique is used to determine K s and K d values and subsequently identify the oscillatory stability conditions in the SMIB. The ability of PSO is compared with those of evolutionary programming (EP) techniques and artificial immune system (AIS). The least square (LS) method is selected as the benchmark for K s and K d values determined by PSO, EP, and AIS. Simulation results show that PSO successfully estimated K s and K d values closest to LS compared with EP and AIS. PSO also uses lower computational time compared with those of the two other techniques. The proposed technique is suitable for solving oscillatory stability problems based on the determination of eigenvalues and minimum damping ratio.
This research focused on the development of a mercury-free light source through the use of radio frequency (RF) and microwave discharges. RF at 13.56 MHz and microwave at 2.45 GHz were applied to ...generate the plasma. With the use of this kind of high frequency power generator, plasma can be ignited without using the electrodes inside the chamber or discharge tube, which could significantly increase the lamp lifetime. The potential for high luminance, excellent colour rendering and environmental-friendliness makes xenon the most promising candidate as the replacement for the mercury fluorescent lamp. In this research, RF energy at 13.56 MHz was induced to the cylindrical discharge tube in order to investigate the characteristics of the xenon RF-inductively coupled plasma discharge as a light source. The luminance, spectral distribution and colour rendering index were measured. The values of the luminance and colour rendering index were comparative to the values for a conventional discharge lamp. For microwave plasma, in order to develop a planar-type lamp, surface wave plasma was applied. A few types (transverse, inclined, longitudinal) of slot antennas were tested and the lamp brightness and discharge uniformity were evaluated. The chamber window (front or rear) was coated with a three-colour phosphor from the combination of red, green and blue phosphors and the excitation effect was investigated. From phosphor coating and slot structure optimisations, lamp luminance and discharge uniformity could be improved.
This work focused on the electrical and Hall Effect of Organic Solar cell (OSC). In this work, Indium Tin oxide (ITO) glass as substrate was heated at 50 °C to 200 °C. The polymer used was Poly ...(3-Dodecylthiophene) (P3DT) thin film and Downy Rose Myrtle berries (Rhodomyrtus Tomentosa (Ait.) Hassk.) as dye. The P3DT were deposited on the ITO substrate using electrochemistry method at room temperature. While, the dye of Downy Rose Myrtle berries was deposited by layered using spin coating method. The electrical conductivity of ITO deposited thin film was explored by four point probes (FPP) under dark and under light radiation (range of 10 Wm-2 to 200Wm-2). From FPP study, the electrical conductivity was increased by the increment of light intensity and temperature of substrate. Lastly, the samples were examined using Hall Effect measurement to obtain the type of sample, Hall mobility, and highest charge carrier in the sample of OSC. The results show that the sample is suitable for further solar cell application.
This paper aimed at investigating the performance of plasma windowing concept in terms of radiation pattern, gain, and S-parameter. The antenna structure consists of 12 tubes of commercial ...fluorescent lamps that contain a mixture of mercury vapor and argon gas, which upon electrification, forms plasma. After getting sufficient voltage, the gas inside the fluorescent tube will ionize to plasma and form a plasma column. When all of the tubes surrounding the antenna are electrified, the radiation is trapped inside. By leaving one or more of the tubes in a nonelectrified state, apertures are formed in the plasma shield, which allow radiation to escape. The plasma frequency in this experiment is equal to 5.634e11 Hz. This antenna design is at 4.9 GHz. The designing of plasma antenna using fluorescent tubes has created advancement in antenna industry especially in reconfigurable antenna field.
Hybrid solar cell (HSC) in a form of novel photovoltaic is considered among promising research topic due to its low cost's preparation and environmental friendly solar cells. This paper concerns a ...systematic study on concentration of TiO2 and effect of coating techniques towards solar cells's efficiency. However, this paper is limited to doctor blade and spin coating techniques only. These samples were then characterised based on morphology, thickness, optical absorption, electrical conductivity and solar cell's efficiency using various techniques including FESEM, profilometer, UV-Vis and, autolab with irradiance of 100 mW/m2. From the results, TiO2/PEDOT:PSS with dye Eugenia clavifora (EC) obtained the highest efficiency of 1.33% using doctor blade technique compared to 0.00108% for spin coating technique. Sample thickness was obtained at 60.25 ± 1.20 nm corresponding to the concentration of TiO2 at 0.20 M. Thus, it can be conclude that, power conversion efficiency (PCE) was dependent to the deposition techniques of the thin film.
High performances of Hybrid Dye Sensitized Solar Cell are necessary in absorbing more sunlight and needed renewable energy source to replace depleted fossil fuels via green energy. Hybrid DSSC is ...another promising option towards green energy to explore. This research aims, i) to study conjugated chlorophyll in order to increase charge carrier in molecule structure besides, increase the absorption spectrum via conjugating process with the addition of different amount Ferric (III) Chloride (FeCl3) acting as catalyst and, ii) to determine the effect of FeCl3 on the performance of conjugated dye as sensitizers in Hybrid DSSC. The conjugated chlorophyll shows a using UV-Visible analysis corresponding to conjugated chlorophyll absorbed in high region called red shifted which the maximum absorption obtain at a wavelength of 360nm and 311nm. Fourier Transform Infra-Red characterization of the an existing Fe-O bond appears at 430 cm-1 to 445 cm-1 and C≡C bond at 2244 cm-1 to 2260 cm-1. 10% FeCl3 in conjugated chlorophyll produce huge impact to electrical conductivity and efficiency with the highest value; 0.114 S/cm and 0.14%; respectively. Thus, it can be conclude that 10% FeCl3 of conjugated chlorophyll – Imperata cylindrica (iCHLO-IC) was suitable to be used for the next generation of hybrid DSSC.
Plasma is the fourth state of matter. It is a common state of matter where almost of the universe in a plasma state and it can be found on earth naturally or artificially. The advantages of using ...plasma antenna are it is invisible to radar, no ringing effect, more efficient, dynamically reconfigurable and has fast transmission. The aim for this study is to investigate the effect of winds and humidity on radio signal using plasma antenna as an alternative to the conventional metal antenna. This research used two different type of commercial fluorescent lamps which are tubular (cylinder) and 2U-shape as plasma antenna. Thus, this kind of antenna can be considered as multi-function as it is originally a light source. The plasma antenna parameters such as return loss, gain and radiation pattern were characterized. In order to realize that, plasma parameters i.e., plasma and collision frequencies need to be obtained. The electrical properties measurement need to be done to record the values of current and voltage, then were used in GLOMAC programming to calculate the plasma parameters. The next stage was the simulation of plasma antenna using CST software. The last stage is signal strength experiment to get the value for radio signal strength received by plasma antenna. Then, the value of radio signal strength in against time was recorded. From the results, as the wind speed over time decreases, the power level decreases and vice versa. From the simulation results, the radiation pattern for tubular and 2U can be categorized as omni-directional pattern. Generally, good correlation was accomplished to prove the wind speed and humidity effect on radio signal using plasma antenna.
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