September 2013

Plasma properties of nano-second laser ablated iron target in air

In the present work, we studied the optical emission spectra of iron (Fe) plasma produced by the fundamental (1064 nm) and second (532 nm) wavelengths of an Nd: YAG laser. The plasma emission has been recorded spatially using five spectrometers covering the spectral region from 200 to 720 nm. The laser beam was focused on target material by placing it in air at atmospheric pressure. The experimentally observed line...

Author(s): Muhammad Salik, Muhammad Hanif , Jiasheng Wang and Xiqing Zhang

September 2013

Wavelet based dynamic Mel Frequency Cepstral Coefficients (MFCC) and block truncation techniques for efficient speaker identification under narrowband noise conditions

Speaker identification strategies are well convincing in their performance when clean speeches are scrutinized. But the performance degrades when speech samples are corrupted by narrowband noise. Block truncation of the cepstral coefficients ensures that not all the features are affected by narrowband noise but it cannot reduce the extent of degradation. This work is focused towards improving the performance of speaker...

Author(s): S. Selva Nidhyananthan, R. Shantha Selva Kumara and D. S. Roland

September 2013

Performance analysis of a Ĉuk regulator applying variable switching frequency

This paper examines the performance of Ĉuk regulator to convert three phase alternating current (ac) to direct current (dc). Firstly, three phase ac is rectified with bridge diode. The rectified dc voltage is applied to input of a Ĉuk regulator.  Three phase harmonics filter is introduced at the input of the diode rectifier to improve the shape of the input current. The main technique applied here to improve the...

Author(s): Md. Nazmul Hasan, Md. Shamimul Haque Choudhury, M. Shafiul Alam, and Muhammad Athar Uddin,

September 2013

Geoelectrical studies for the delineation of potential groundwater zones at Oduma in Enugu State, Southeastern Nigeria

This work evaluates the use of geoelectrical method in the delineation of potential groundwater zones at Oduma in Enugu state, Southeastern Nigeria. Oduma lies within latitudes 6°02Ë¡ N to 6°07Ë¡ N and longitudes 7°35Ë¡ E to 7°41Ë¡ E with an area extent of about 102.6 km2. The area is underlain by Awgu Shale group with its lateral arenaceous facie; Owelli Sandstone outcropping south...

Author(s): Austin, C. OKONKWO and Isaac, I. UJAM