Electronics

  2010 SEP 8 - (VerticalNews.com) -- "Since the contact-less power transmission system accomplishes power transfer using magnetic coupling of the transformer without a mechanical contact, it has the advantages of electric isolation, safety, reliability, low maintenance and a long-product life. However, a contact-less transformer with a large air gap has a low coupling coefficient and high leakage inductance," scientists writing in the International Journal of Electronics report ...read more

  2010 SEP 8 - (VerticalNews.com) -- "This article proposes two new methods for improving the performance of a synchronous-rectifier forward converter. A synchronous-rectifier converter produces a reverse current in the inductor due to the bidirectional characteristic of MOSFETs while the converter is turned off," investigators in Taipei, Taiwan report.

  "This reverse current causes voltage spikes which may damage the power devices. This article proposes two methods to reduce the voltage spikes: method 1 and method 2. 1 uses the enable signal detection method. An enable signal is generated from the remote control of the system when the main power is turned off. Then, the proposed circuit of method 1 turns off the free-wheeling switch before the reverse current is produced. As a result, the voltage spike can be avoided. 2 uses a transformer winding to detect the turn-off time of the input power. Then, the circuit turns off the free-wheeling switch to break the resonant loop and end the reverse current. The cost analysis of method 1 and 2 is included," wrote T.H. Liu and colleagues ...read more

  2010 SEP 8 - (VerticalNews.com) -- "A boundary refinement method using a new hidden Markov model (HMM) topology is proposed for automatic phonetic speech segmentation," scientists in Ankara, Turkey report.

  "The proposed method has the ability to work at high frame rates and the training and boundary refinement stages are easy and fast. The method is data driven and can be adapted to any speech segmentation problem provided that a training set is available," wrote E. Akdemir and colleagues, Middle East Technical University ...read more