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Tweek atmospherics are Extremely Low Frequency (ELF) and Very Low Frequency (VLF) radio waves produced by lightning discharge. For few decades, tweeks has been known to be useful in measuring the variations of the lower region of the ionosphere (D-region). However, due to the nature of lightning occurrences, it is difficult to determine the location of source for the tweeks signal. In this study, we determine the source location of the tweeks by accurately measuring the time of the lightning impulse. The source locations are based on lightning information by the World Wide Lightning Location Network (WWLLN). A nighttime sample of tweeks were collected on the 11th November 2010 shows tweeks were found to have ±600 km in difference between the calculated lightning propagation distance and the location found in the WWLLN lightning activity. Next, this study shows the variations of the D-region ionosphere using tweeks with the known source locations.

In this paper, the pulse with modulation as switching strategy for neutral point type buck-boost converter is introduced. The proposed control strategy is implemented and applied to electronic ballast by using neutral point type buck boost converter. The circuit is composed from two ideal switches and Metal Oxide Semiconductor Field Effect Transistor which in its common source configurations used as switching technique. Switching model is developed in Matlab/Simulink on order to control neutral point type buck boost converter. This has resulted to reduction in harmonics current. In realizing its effectiveness and performance, the proposed switching technique has been applied to electronics ballast and lamp. Results obtained from the study indicate that the proposed switching technique is feasible for further applications.

The renewable-energy sector is fast gaining ground as a new growth area for numerous countries with the vast potential it presents environmentally and economically. Solar energy plays an important role as a primary source of energy, especially for rural area. This paper presents the design and development of high-efficiency dual-axis solar tracking system using Arduino platform. Furthermore, the ultimate objective of this project is to trace the maximum sunlight source to power the solar panel. The project is divided into two stages, which are hardware and software development. In hardware development, five light dependent resistor (LDR) has been used for capturing maximum light source. Two servo motors have been used to move the solar panel at maximum light source location sensing by LDR. Moreover, the code is constructed using C programming language and targeted to Arduino UNO controller. The efficiency of the system has been tested and compared with static solar panel on several time intervals, and it shows the system react the best at the 10-minutes intervals with consistent voltage generated. Therefore, the system has been proven working for capturing the maximum sunlight source for high efficiency solar harvesting applications.

In this paper, we study the performance of optical code-division multiple access (OCDMA) systems using vector combinatorial (VC) code under various link parameters. The impact of the fiber dispersion effects on the multi-user interference (MUI) is reported using a commercial optical systems simulator, Virtual Instrument Photonic, VPItransmissionMaker™. The VC code is compared mathematically with other codes which use similar techniques. We have analyzed and optimized the data rate, fiber length, and channel spacing in order to reduce the BER without the need to deploy dispersion compensating devices. We have demonstrated that, for a high data rate (higher than 2.5 Gb/s), even if dispersion compensated devices are not deployed, the BER can be significantly improved when the VC code desired parameters are selected. It is clearly seen that the MUI noise has been eliminated effectively.