ARTICLE INFO ABSTRACT ARTICLE HISTORY: Received 15 September 2012 Revised 15 August 2013 Accepted 22 August 2013 This paper presents a novel control method to improve the efficiency of low-voltage DC-DC converters at light loads. Pulse Width Modulation (PWM) converters have poor efficiencies at light loads, while pulse frequency modulation (PFM) control is more efficient for the same cases. Swi...

We describe the environment effects on the amount and quality of resources collected by Melipona rufi ventris Lepeletier in the Atlantic Forest at Ubatuba city, São Paulo state, Brazil (44o 48’W, 23o 22’S). Bees carrying pollen and/or nectar were captured at nest entrances during 5 min every hour, from sunrise to sunset, once a month. Pollen loads were counted and saved for acetolysis. Nectar w...

Effects of water stress on fruit fresh and dry weights were investigated in peach trees, Prunus persica (L.) Batsch., with varying crop loads: light, moderate and heavy. In well-watered controls, tree water status was independent of crop load. In trees receiving reduced irrigation, the degree of water stress increased with increasing crop load. Water stress induced fruit fresh weight reductions...

The objective of the research is to optimize the empennage of a light weight aircraft such as Zenith aircraft. The case is specified by a unique set of geometry, materials, and strength-to-weight factors. The anticipated loads associated with the empennage structure are based on previous light aircraft design loads. These loads are applied on the model to analyze the structural behavior conside...

With the wind turbines being produced toward to large scale and light weight, the flexibility of blade, drive mechanism and tower increase apparently. Loads suffered by wind turbines during operation become increasingly intricate. Some control approaches could be used to cut down these loads in orde to expand life cycle of generating sets. Aiming at the full load operation zone above rated wind...