Volume: 3
Number: 2
July-December 2004

To see an article directly, click its Title. To see abstract, click its [Abstract] link.

• NUMERICAL INVESTIGATION OF NATURAL CONVECTION INSIDE ECCENTRIC HORIZONTAL ANNULUS FILLED WITH SATURATED POROUS MEDIA - VERTICAL ECCENTRICITY
  Ahmed F. Alfahaid
  Abstract PDF
  NUMERICAL INVESTIGATION OF NATURAL CONVECTION INSIDE ECCENTRIC HORIZONTAL ANNULUS FILLED WITH SATURATED POROUS MEDIA - VERTICAL ECCENTRICITY
  Ahmed F. Alfahaid

  Abstract

  A numerical investigation of natural convection inside eccentric annulus filled with saturated porous medium is carried out. The solution scheme is based on two-dimensional model, which is governed by Darcy-Oberbeck-Boussionseq equation. The inner cylinder is heated isothermally while the outer one is cooled isothermally. Discretization of the governing equations is achieved using finite element scheme based on Galerkinmethod of weighted residuals. The effect of pertinent parameters such as modified Rayleigh number (Ra) and relative eccentricity for radius ratio of 2 are considered in this study. The modified Rayleigh number ranges from 10 to 400 while the relative eccentricity () ranges from 0.1 to 0.8.
  The numerical results obtained from the present model are compared with the available published results. An overall good agreement is observed between the current results and the available published results.
• EXPLORING THE ABILITY OF CUTTING EXPANDABLE POLYSTYRENE SHEET WITH LOOP HOTWIRE
  Riza Sulaiman
  Abstract PDF
  EXPLORING THE ABILITY OF CUTTING EXPANDABLE POLYSTYRENE SHEET WITH LOOP HOTWIRE
  Riza Sulaiman

  Abstract

  Foam materials such as expandable polystyrene sheet (EPS) have variety of uses. In order to optimize these uses, EPS are usually cut into different shapes and sizes. There are two ways of cutting foam materials, the Hotwire Technique and the Oscillating Blade Technique. Both produce different features to the foams. The oscillating blade produces simple geometrical shapes and is suitable for rigid foams. The hotwire technique is capable for producing complicated geometrical shapes and is suitable for flexible foams. This paper discusses and on-going research to produce a pared-prototyping machine,which cuts polystyrene models using the Hotwire Technique. One of the phases of this research is to determine the surface form of EPS after being cut using a looped-shape hotwire foam cutter. The main interest is to explore the possibility of using a loop-shaped hotwire instead of the conventional straight-tensioned hotwire.
• A NOVEL APPROACH TO NOISY SPEECH RECOGNITION USING DTW ALGORITHM WITH MEL-FREQUENCY CEPSTRAL COEFFICIENTS
  Rishad Ahmed Shafik, Fazli Qayyum Yousaf-Zai
  Abstract PDF
  A NOVEL APPROACH TO NOISY SPEECH RECOGNITION USING DTW ALGORITHM WITH MEL-FREQUENCY CEPSTRAL COEFFICIENTS
  Rishad Ahmed Shafik, Fazli Qayyum Yousaf-Zai

  Abstract

  A new and effective approach to recognition of noisy speech is introduced. End-Point-Detection algorithm is used to measure the noise power and to automatically initiate recording of a spoken word. Unvoiced components of the recorded speech, buried in noise, viz. Ambient noise or hiss noise or telephone noise, were then optimally minimized by Yulewalk Finite Impulse Response (FIR) band pass Filter. The speech signal was then sampled and speech features were extracted using Mel-Frequency Cepstral Coefficients (MFCC), which were later dynamically time-warped to find the average minimal distance from Euclidean distance matrices to help facilitate the recognition of speech. For generalization, speech data from three speakers, of three different level of pitch, were collected and ware compared to a mid-pitch speaker. This work will be extended to establish both speaker independent and speaker dependent efficacy and accuracy in future. Such a speech recognition system can be both fast and effective even in moderately hostile environments.
• AN EXPERIMENTAL INVESTIGATION OF HEAD LOSS THROUGH LOCALLY MADE STRAINERS FOR HAND TUBE-WELLS OF BANGLADESH
  Sukalyan Bachhar, M.Q. Islam, A.C. Mandal
  Abstract PDF
  AN EXPERIMENTAL INVESTIGATION OF HEAD LOSS THROUGH LOCALLY MADE STRAINERS FOR HAND TUBE-WELLS OF BANGLADESH
  Sukalyan Bachhar, M.Q. Islam, A.C. Mandal

  Abstract

  In this paper, an experimental investigation has been carried out for flow through locally made polyvinyl chloride (PVC) strainers of hand tube-wells used in Bangladesh. The head loss associated with this strainer has also been obtained. Minor loss coefficient for the strainer has been calculated based on Reynolds number. It is found that the average value of minor loss coefficient is equal to 0.27 and it decreases with the increase of Reynolds number.
• MODULATION DIVERSITY IN ULTRA-WIDEBAND SYSTEMS FOR INCREASED THROUGHPUT
  M.E.R.Khan, Kazi M. Ahmed
  Abstract PDF
  MODULATION DIVERSITY IN ULTRA-WIDEBAND SYSTEMS FOR INCREASED THROUGHPUT
  M.E.R.Khan, Kazi M. Ahmed

  Abstract

  Currently Ultra-wideband (UWB) technology has drawn huge attention of researchers as well as of communications industry. For generic pulse based UWB systems. Pulse Position Modulation (PPM) or Pulse Amplitude Modulation (PAM) are most suitable signal formats. For UWB systems Binary PAM can also be thought of Binary Phase Shift Keying (BPSK) modulaton. To date, only purpose of combining PPM and BPSK is to remove spectral lines in the Power spectrum density (PSD) of UWB transmission since these spectral lines in the Power spectrum already present narrowband services. Because of using bipolar pulses, at the receiver template signal also should be changed. In this paper it is shown that in addition to offering better spectral characteristics bipolar pulses can also offer better BER performance. Explanation is given and result shows that bipolar pulses can give 4 dB SNR gain.
• THE WRITE-OWNER PROTOCOL FOR ENSURING SEQUENTIAL CONSISTENCY OF DSM IN DISTRIBUTED COMPUTING SYSTEM.
  Al-Mukaddim Khan Pathan
  Abstract PDF
  THE WRITE-OWNER PROTOCOL FOR ENSURING SEQUENTIAL CONSISTENCY OF DSM IN DISTRIBUTED COMPUTING SYSTEM.
  Al-Mukaddim Khan Pathan

  Abstract

  The existing protocols used to implement replicated, migrating blocks (RMB) strategy for ensuring the sequential consistency in distributed shared memory (DSM), suffers from excessive cost. In this paper, an efficient protocol named as the Write-Owner Protocol has been proposed using the binding agent for RMB strategy. The goal is to minimize the cost as well as to increase the performance. The proposed protocol uses a hash table to maintain the modification as well as location and owner information of the data blocks with the version number(s).Though some overhead is associated with it, other factors fend to dominate and this small overhead is usually negligible.