A New Wideband Circularly Polarized Dielectric Resonator Antenna

A wideband and compact circularly polarized (CP) C-shaped dielectric resonator antenna (DRA) is presented. The proposed C-shaped DR is excited by a simple stripe line connected to a coplanar waveguide (CPW) feeding line. The C-shaped DRA is circularly polarized with 19% axial ratio (AR) bandwidth. It is found that the CP bandwidth can be expanded by using a narrow short circuit strip. The final design achieves CP with 50% AR bandwidth. The proposed circularly polarized DRA (CPDRA) with good radiation characteristics offers an impedance bandwidth of 58% between 3.45 and 6.26 GHz for VSWR ≤ 2. The proposed DRA is fabricated and tested. Very good agreement between simulated and measured results is obtained

Kesan penggunaan koswer multimedia animasi visual terhadap pencapaian pelajar dalam mata pelajaran matematik

Ramai pelajar yang bermasalah dalam topik Pelan dan Dongakan. Ini kerana pelajar sukar untuk membayangkan objek yang tersembunyi melalui proses pengajaran dan pembelajaran (P&P) secara konvensional. Penyelidik telah membangunkan satu koswer multimedia animasi visual dalam topik Pelan dan Dongakan dengan menerapkan kesemua elemen-elemen yang dapat membantu meningkatkan kemahiran visual iaitu elemen animasi, video, audio, grafik dan teks. Seterusnya, kajian kuasi eksperimental ini turut dijalankan bertujuan untuk mengetahui kesan penggunaan koswer multimedia animasi visual terhadap pencapaian pelajar bagi mata pelajaran Matematik di sekolah menengah. Ujian Pra dan Ujian Pos digunakan untuk melihat perbezaan pencapaian yang signifikan selepas menggunakan koswer multimedia animasi visual yang menggunakan teori Kognitif Visual Wiley. Responden yang terlibat dalam kajian ini ialah seramai 40 orang pelajar Tingkatan Lima yang dibahagikan kepada dua kumpulan iaitu kumpulan rawatan dan kumpulan kawalan yang dipilih daripada sebuah sekolah di daerah Batu Pahat, Johor. Hasil analisis menunjukkan peningkatan skor min markah bagi pelajar kumpulan rawatan. Hasil analisis ujian-t (paired-sample-t-test) membuktikan bahawa wujudnya perbezaan skor min markah yang signifikan di antara markah ujian pra dan markah ujian pos bagi kumpulan rawatan. Oleh itu, terdapat perbezaan yang signifikan di antara skor min markah ujian pra dan ujian pos bagi pelajar kumpulan rawatan selepas menggunakan koswer multimedia animasi visual. Manakala instrumen soal selidik yang digunakan untuk melihat tahap penerimaan pelajar selepas menggunakan koswer multimedia animasi visual berdasarkan tiga aspek iaitu aspek isi kandungan, aspek interaksi dan aspek persembahan telah memeperolehi skor min yang tinggi bagi ketiga-tiga aspek tersebut. Dapatan kajian ini menggambarkan penggunaan koswer multimedia animasi visual dapat membantu meningkatkan pencapaian Matematik di dalam bilik darjah terutama yang tidak melibatkan pengiraan

Analysis of Pressure Effects for Current Density and Electric Field Performance of Gas Insulations

Gas insulation had been used widely in high voltage industry as a dielectric component. According to the arrangement of gas particles that far apart from each other, lead to the movement of gas particles react fast with high temperature and pressure. Hence when breakdown occurred in a system, it will quickly protect the system by diminished the sparks to avoid flashover occurred. The intention of this research is to determine relationship between current density and electric field of gas insulations that have been used in the insulator. HV experimental test has been conducted, to obtain breakdown voltage of air to use as applied voltage in the simulation for breakdown purpose of three insulation gasses, which are Sulphur Hexafluoride (SF6), Octafluoropropane (C3F8), and Nitrogen (N2). Physical properties such as thermal conductivity, electrical conductivity, and temperature of each gasses are require to identify value of current density and electric field of each insulation gasses. Furthermore, two pressure spots were placed symmetrically between two electrodes in the insulator. Based on simulation’s results, C3F8 is the best gas insulation because in normal condition and when presence of pressures it had lowest current density compared to SF6 and N2. Thus, C3F8 had the highest value of electric field among the insulation gasses. Electrical insulator is an internal electrical charger that cannot move freely and its contrast with semiconductors and conductors that can conduct electrical current easily. When the insulating material was used to avoid electrical discharges, it’s called insulation. High voltage insulation has been used widely in industry at electrical equipment such as switchgear and circuit breaker. The importance of applied high voltage in the electrical equipment is to prevent it from damage when faulty or breakdown occurs. From the results that have been obtained, the best gas insulation can be applied in the insulator as a protective component in electrical industry

A putative probiotic isolated from hatchery reared juvenile Penaeus monodon

Probiotic is considered as a remedy to solve disease problem in shrimp aquaculture. Shrimp body and environment bacterial flora are recommended as reliable source for extracting of beneficial bacteria. Therefore, 5000 pieces of post larvae of Penaeus monodon were distributed equally in 4 tanks in probiotic and antibiotic free condition up to juvenile. Then microbiological samples from digestive system, muscles, body surface, rearing water and tank sediment were inoculated onto the selective media plates. Incident of total bacteria, Vibrio, Pseudomonas and Entrobacteriaceae were evaluated in different body parts and rearing environment of shrimp. The highest bacteria count for total bacteria, Vibrio, Pseudomonas was occurred in sediment followed by digestive system. No Entrobacteriaceae was observed from all samples. Isolated bacteria were identified and placed in 7 genera consisted of Vibrio, Shewanella, Burkholderia, Clavibacter, Staphylococcus, Brevibacterium, Corynebacterium, while one genus remained unidentified. Genus Shewanella exhibited highest frequent bacteria in digestive system of P. monodon which may be indicated its ability to colonization in digestive system. Shewanella algae was selected from whole isolated bacteria as candidate probiotic via well plate diffusion technique and cross streak antagonistic test against Vibrio harveyi, V. parahaemolyticus and V. alginolyticus. It was able to digest lipid and protein in tributyrin agar and skim milk agar

Face recognition based on singular valued decomposition and back progagation neural network

This paper presents a developed face recognition system. The method used singular valued decomposition as images feature extractor and back propagation neural networks as its classifier. The back propagation training parameters are varied in order to find the best parameter with the highest performance accuracy. The results from experiments have showed that combinations of both methodologies give good recognition rate and therefore considered as an effective face recognition system

Training needs assessment in Malaysia: Exercise held at Kuala Lampur and Kota Bharu from 13th October 1989

Training / Irrigation / Evaluation / Malaysia

A comparative study of proximate composition of Artemia urmiana enriched with different sources and levels of HUFA

The nutritional quality of commercially available Artemia strains is relatively poor in Eicosapentaenoic acid (EPA), Arachidonic acid (ARA) and especially Docosahexaenoic acid (DHA). Hence, it is essential and common practice to enrich this live prey with emulsions of special oils. One commercial ICES30/4 (Belgium), Linseed oil as a vegetable oil, Cod liver oil and Sturgeon ovary oil as two animal oils with EPA amounts in these oils were 6.29, 0.03, 11.39, 7.55 and the DHA amounts were 20.90, 0.00, 7.64, 2.76 respectively with three concentrations (100, 200 and 300ppm) during two enrichment periods (12 and 24h) were tested in order to improve the HUFA content, the DHA/EPA ratio and ARA content of Artemia urmiana nauplii. The results showed that Artemia enriched with different levels of vegetable oil and enrichment periods was poor in relation to either HUFA content or DHA/EPA ratio but the fish oils and emulsion resulted in HUFA incorporation. Sturgeon ovary oil caused the poorest DHA/EPA ratio enrichment (0.40 in 300ppm-24h) but the commercial emulsion (ICES30/4) was found as the best for DHA/EPA ratio enrichment (1.20 in 300 ppm- 24h). Cod liver oil (0.53 in 100ppm-24h) can be a good internal source substitute for improving the DHA/EPA ratio enrichment compared to ICES30/4 due to price and availability. As a result, HUFA content was increased with enrichment level 200ppm during 24h. Also, all oil sources improved lipid and protein percentages in A. urmiana nauplii

Analysis of Electric Field and Current Density on XLPE Insulator

Good condition and size of the insulator are important to ensure the excellent electric field and current density performance because of aging and degradation HVDC cable problem. At present, the existing insulator which is XLPE insulator that had been used does not meet the capabilities criteria of HVDC cable due to the problem in terms of the condition of the insulator which is the presence of a void in the insulator. A research had been made with Quickfield Software to calculate the electric field and current density in the XLPE insulator of HVDC cable. A void is created in the XLPE insulator by using Quickfield Software by varying diameter of void and distance of void from conductor. XLPE insulator is taken as main research object. The results show that largest diameter of void and nearest distance of void from conductor distorts highest electric field and lowest current density. Therefore, it is important to study both electric field and current density to ensure good capabilities and safety of HVDC cable

The effects of pressure dependent constitutive model to simulate concrete structures failure under impact loads

The main objective of this paper is to explore the effect of confining pressure in the compression and tension zone by simulating the behaviour of reinforced concrete/mortar structures subjected to the impact load. The analysis comprises the numerical simulation of the influences of high mass low speed impact weight dropping on concrete structures, where the analyses are incorporated with meshless method namely as Smoothed Particle Hydrodynamics (SPH) method. The derivation of the plastic stiffness matrix of Drucker-Prager (DP) that extended from Von-Mises (VM) yield criteria to simulate the concrete behaviour were presented in this paper. In which, the displacements for concrete/mortar structures are assumed to be infinitesimal. Furthermore, the influence of the different material model of DP and VM that used numerically for concrete and mortar structures are also discussed. Validation upon existing experimental test results is carried out to investigate the effect of confining pressure, it is found that VM criterion causes unreal impact failure (flexural cracking) of concrete structures

AC breakdown behavior of SF6/N2 gas mixtures under non-uniform field electrode configurations

Sulphur hexafluoride (SF6) gas owns remarkable properties as insulation medium and current interrupter, which make it being widely used in gas-insulated equipment up to now. However, SF6 gas has a drawback that gives adverse effect to the environment since it is a strong greenhouse gas. As the effort to minimize the SF6 usage, this study was conducted to investigate the AC breakdown behavior of SF6/N2 gas mixtures with 10/90 ratio at low pressure levels (i.e. 0.11 MPa to 0.15 MPa) under non uniform field (i.e. R0.5-plane and R6-plane electrodes configurations). The results of the study indicate that the breakdown voltage of SF6/N2 gas mixtures in non-uniform field increases linearly with the increase of gas pressure and electrodes gap distance. As a function of gap distance, a higher increasing rate of breakdown voltage values were achieved at lowest pressure of 0.11 MPa compared to other pressure levels. In addition, it is also found that a higher breakdown voltage values was obtained under R6-plane configuration. But, the difference in breakdown voltage values between R0.5-plane and R6-plane configuration is less significant as the gap distance is increased. It is also observed that the field efficiency factor of R6-plane is higher than R0.5-plane which indicates a more uniform field exists between the electrodes