Current Issue : January - March Volume : 2015 Issue Number : 1 Articles : 5 Articles
This paper presents a charger and LED lighting (discharger) hybrid system with a PV array as its power source for electronic\nsign indicator applications. The charger adopts buck-boost converter which is operated in constant current mode to charge leadacid\nbattery and with the perturb and observe method to extract maximum power of PV arrays. Their control algorithms are\nimplemented by microcontroller.Moreover, forward converter with active clamp circuit is operated in voltage regulation condition\nto drive LED for electronic sign applications. To simplify the circuit structure of the proposed hybrid converter, switches of two\nconverters are integrated with the switch integration technique. With this approach, the proposed hybrid converter has several\nmerits, which are less component counts, lighter weight, smaller size, and higher conversion efficiency. Finally, a prototype of LED\ndriving system under output voltage of 10V and output power of 20W has been implemented to verify its feasibility. It is suitable\nfor the electronic sign indicator applications....
Metal/semiconductor and transparent conductive oxide (TCO)/semiconductor heterojunctions have emerged as an effective\nmodality in the fabrication of photoelectric devices. This review is following a recent shift toward the engineering of TCOlayers and\nstructured Si substrates, incorporating metal nanoparticles for the development of next-generation photoelectric devices. Beneficial\nprogress which helps to increase the efficiency and reduce the cost, has been sequenced based on efficient technologies involved in\nmaking novel substrates, TCOlayers, and electrodes. Theelectrical and optical properties of indium tin oxide (ITO) and aluminum\ndoped zinc oxide (AZO) thin films can be enhanced by structuring the surface of TCO layers. The TCO layers embedded with\nAg nanoparticles are used to enhance the plasmonic light trapping effect in order to increase the energy harvesting nature of\nphotoelectric devices. Si nanopillar structures which are fabricated by photo lithography-free technique are used to increase lightactive\nsurface region.The importance of the structure and area of front electrodes and the effect of temperature at the junction are\nthe value added discussions in this review....
Currently, wearable electronics are increasingly widely used, leading to an increasing need of portable power supply. As a clean and\nrenewable power source, piezoelectric energy harvester can transfer mechanical energy into electric energy directly, and the energy\nharvester based on polyvinylidene difluoride (PVDF) operating in 31-mode is appropriate to harvest energy from human motion.\nThis paper established a series of theoretical models to predict the performance of 31-mode PVDF energy harvester. Among them,\nthe energy storage one can predict the collected energy accurately during the operation of the harvester. Based on theoretical study\nand experiments investigation, two approaches to improve the energy harvesting performance have been found. Furthermore,\nexperiment results demonstrate the high accuracies of the models, which are better than 95%....
This paper explores passive switched capacitor based RF receiver front ends for spectrum sensing. Wideband spectrum sensors\nremain themost challenging block in the software defined radio hardware design. The use of passive switched capacitors provides a\nvery low power signal conditioning front end that enables parallel digitization and software control and cognitive capabilities in the\ndigital domain. In this paper, existing architectures are reviewed followed by a discussion of high speed passive switched capacitor\ndesigns. A passive analog FFT front end design is presented as an example analog conditioning circuit. Design methodology,\nmodeling, and optimization techniques are outlined. Measurements are presented demonstrating a 5GHz broadband front end\nthat consumes only 4mWpower....
This paper introduces modeling and simulation of the noise properties of the blue-violet InGaN laser diodes. The noise is described\nin terms of the spectral properties of the relative intensity noise (RIN). We examine the validity of the present noise modeling by\ncomparing the simulated results with the experimental measurements available in literature. We also compare the obtained noise\nresults with those of AlGaAs lasers. Also, we examine the influence of gain suppression on the quantum RIN. In addition, we\nexamine the changes in the RIN level when describing the gain suppression by the case of in homogeneous spectral broadening.\nThe results show that RINof the InGa Nlaser is nearly 9dB higher than that of the AlGaAs laser....
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