Analysis of Concentric Split Ring Square Element for Broadband Reflectarray Antenna

An investigation of phase variation and phase range of concentric split ring square element for broadband reflectarray antenna is presented in this paper. This is realized by exploiting the physical geometry of three element shapes namely square element, concentric ring square element and concentric split ring square element. Modifying the current distribution of basic concentric ring square element, leads to a less steep phase variation and also the bandwidth performance. An analysis of frequency response is described and analysed. The physical interpretation of the elements is also discussed. The proposed antenna element effectively covers two frequency operations (13.44 GHz and 18.36 GHz) in Ku-band range. Bandwidth broadening is achieved by introducing the ring square combination of element and the practical phase range is achieved through the use of RF 35 (thickness = 1.524 mm) as the substrate. The new concept of split initiates to a wider bandwidth (up to 67.6 %) for the antenna and can applied to any two frequency operations of Ku-band applications

Throughfall at an abandoned skid trail in a tropical rain forest in Peninsular Malaysia

Knowledge of throughfall at abandoned skid trails in tropical forests is extremely scarce. Thus, throughfall was measured using 120 storage rain gauges set on a skid trail left abandoned 41 years after forest harvesting in the Bukit Tarek Experimental Watershed (BTEW) in Peninsular Malaysia. All trees of ≥ 1 m height in the plot were identified to the species level, and their diameter at breast height (DBH) and height were measured. Vegetation along the skid trail comprises trees with smaller DBH (0.2-31.0 cm, with a mean of 2.0 cm) and shorter height (1.0-20.0 m, with a mean of 2.8 m) than those in the regenerated secondary forests of BTEW. The diversity (i.e. 43 families, 131 species) at the skid trail was similar to that in an old tropical forest at BTEW. The ratio of throughfall to gross rainfall (Th/Rg) for 84 rain events ranged from 27.4% to 204.7% with a mean and standard deviation of 98.1% and 33.2%, respectively. We found that a considerable amount of rainwater dropped under bertam (i.e. Eugeissona tristis) and rattan (i.e. Daemonorops callicarpa, Calamus insignis) vegetation. The Th/Rg ratio weakly correlated with canopy openness. The mean Th/Rg ratio is the largest mean ratio ever reported for forests in Malaysia

The design of IPT system for multiple kitchen appliances using class E LCCL circuit

Since many years ago, kitchen appliances are powered up by cable connected. This create a troublesome case as wire might tangle together and cause kitchen table messy. Due to this, wireless power technology (WPT) is introduced as its ability is to transmit power to load without physical contact. This leads to cordless solution better in safety as the product can be completely seal, highly expandable power range. This work focuses on the design of WPT based on inductive approach to power up multiple kitchen appliances. The selection of inductive approach over its partners capacitive and acoustic is mainly due to high power efficiency. Class E inverter is proposed here to convert the DC to AC current to drive the inductive link. A 1 MHz operating frequency is used. To ensure the circuit is robust with load variations, an LCCL impedance matching is proposed. This solution is table to maintain the output power if there is a slight change in load impedance. Finally, the developed prototype is able to supply 50V utput which can achieve power transmission up to 81.76%

The Development of Wireless Power Transfer Technologies for Mobile Charging in Vehicles using Inductive Approach

Nowadays, the mobile charging in vehicle is a must and therefore, such technology is now available in every vehicle through wired connection approach. Using this wired connection to power up mobile device in the vehicle might be inconvenience to the user. Thus, this project aims to develop a wireless power transfer technology to power up the mobile device in a vehicle. Through this, the users will not facing difficulty of charging their device while driving. To be specific, the Inductive Power Transfer (IPT) is applied here due to its advantages where it can transfer power wirelessly with a higher efficiency in a short range. To make this work, a Class E inverter is designed to convert a direct current (DC) supply into alternating current (AC) supply at a high frequency with a higher efficiency. Furthermore, pi-2-a impedance matching circuit is also applied in this work in order to improve the efficiency of such system. To validate the efficiency of the proposed method, analysis on the gap distance between the two magnetic coils, transmitter and receiver, are performed through simulation and experimental work. At the end of this work, the designed prototype is able to yield approximately 70 % in terms of output efficiency and able to power up the mobile device wirelessly

Genetic Variation, Heritability, and Diversity Analysis of Upland Rice (Oryza sativa L.) Genotypes Based on Quantitative Traits

Upland rice is important for sustainable crop production to meet future food demands. The expansion in area of irrigated rice faces limitations due to water scarcity resulting from climate change. Therefore, this research aimed to identify potential genotypes and suitable traits of upland rice germplasm for breeding programmes. Forty-three genotypes were evaluated in a randomised complete block design with three replications. All genotypes exhibited a wide and significant variation for 22 traits. The highest phenotypic and genotypic coefficient of variation was recorded for the number of filled grains/panicle and yields/plant (g). The highest heritability was found for photosynthetic rate, transpiration rate, stomatal conductance, intercellular CO 2 , and number of filled grains/panicle and yields/plant (g). Cluster analysis based on 22 traits grouped the 43 rice genotypes into five clusters. Cluster II was the largest and consisted of 20 genotypes mostly originating from the Philippines. The first four principle components of 22 traits accounted for about 72% of the total variation and indicated a wide variation among the genotypes. The selected best trait of the number of filled grains/panicle and yields/plant (g), which showed high heritability and high genetic advance, could be used as a selection criterion for hybridisation programmes in the future

Relationship between high temperature and formation of chalkiness and their effects on quality of rice

Occurrence of chalkiness in rice is attributed to genetic and environmental factors, especially high temperature (HT). Te HT induces heat stress, which in turn compromises many grain qualities, especially transparency. Chalkiness in rice is commonly studied together with other quality traits such as amylose content, gel consistency, and protein storage. In addition to the fundamental QTLs, some other QTLs have been identifed which accelerate chalkiness occurrence under HT condition. In this review, some of the relatively stable chalkiness, amylose content, and gel consistency related QTLs have been presented well. Genetically, HT efect on chalkiness is explained by the location of certain chalkiness gene in the vicinity of high-temperature responsive genes. With regard to stable QTL distribution and availability of potential material resources, there is still feasibility to find out novel stable QTLs related to chalkiness under HT condition. A better understanding of those achievements is essential to develop new rice varieties with a reduced chalky grain percentage. Therefore, we propose the pyramiding of relatively stable and nonallelic QTLs controlling low chalkiness endosperm into adaptable rice varieties as pragmatic approach to mitigate HT effec

Performance analysis of stacked capacitive antenna for lightning remote sensing

Antennas are the important elements in the lightning detection system. To improve performance of the lightning detection system, it is so necessary to improve the efficiency of the antennas. There are two types of antennas used in the system which are capacitive antenna for electric field sensing and loop antenna for magnetic field sensing [1]. Both of these antennas are big in size and causing inconvenient during set up. Thus, small and portable antennas are designed. It is so important to remain or improve the sensitivity of the antennas even though it is small in size. Stacking method is used in capacitive antenna by increase copper plate layer in between the parallel plate antenna. After prototype the multi-stacked capacitive antenna, performance analysis is carried out. Performances of the antennas are compared using CST simulation and hardware set up. Multi-stacked capacitive antenna is compared with the single plate antenna and found that the performance of the antenna increases as the stacked number increases

Evaluation of air-gap stacked capacitive antennas for lightning remote sensing

This paper evaluates the capacitive antenna performance (sensitivity and frequency shifting) as a lightning sensor in different antenna design structures. Two experiments were carried out, Experiment A - using two different structure antennas, an A3 size capacitive antenna and a quarter A4- sized capacitive antenna, capturing the electric field (E-field) generated by the small spark at a distance of 1 meter away from both antennas. The results were taken in a ratio form of the 1st pulse amplitude captured by quarter A4 size antenna verses 1st pulse amplitude of the waveform captured by A3 antenna for each corresponding spark. Same set up and measurement were taken during the Experiment B except for the quarter A4 size antenna was now being slotted with 6 copper plates were slotted within the gap between the top plate and bottom plate. The result from Experiment A showed an average ratio at 0.1957 with a range of 0.0333 to 0.3085 while the results of Experiment B showed the average value laid at 0.2606 within the range of 0.1581 to 0.4510. The comparison results of Experiment A with Experiment B gave an increment of the sensitivity of the quarter A4 antenna from no stack to fully stacked antenna. However, there was also a significant frequency shifting of the quarter A4 antenna with the change of antenna structure (15% for quarter A4 capacitive antenna without stack; 20% for quarter A4 stacked capacitive antenna)

Isoprene hotspots at the Western Coast of Antarctic Peninsula during MASEC′16

Isoprene (C5H8) plays an important role in the formation of surface ozone (O3) and the secondary organic aerosol (SOA) which contributed to the climate change. This study aims to determine hourly distribution of tropospheric isoprene over the Western Coast of Antarctic Peninsula (WCAP) during the Malaysian Antarctic Scientific Expedition Cruise 2016 (MASEC′16). In-situ measurements of isoprene were taken using a custom-built gas chromatography with photoionization detector, known as iDirac. Biological parameters such as chlorophyll a (chl-a) and particulate organic carbon (POC) were compared to the in-situ isoprene measurements. Significant positive correlation was observed between isoprene and POC concentrations (r2 = 0.67, p < 0.001), but not between isoprene and chl-a. The hotspots of isoprene over maritime Antarctic were then were investigated using NAME dispersion model reanalysis. Measurements showed that isoprene mixing ratio were the highest over region of King George Island, Deception Island and Booth Island with values of ∼5.0, ∼0.9 and ∼5.2 ppb, respectively. Backward trajectory analysis showed that air masses may have lifted the isoprene emitted by marine algae. We believe our findings provide valuable data set of isoprene estimation over the under sampled WCAP