JOURNAL OF ENGINEERING AND TECHNOLOGY

Journal Browsing

Volume: 5
Number: 2
July-December 2006

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

  • Numerical simulation of the effect of turbulence strength on shock/turbulence interaction
    Mohammad Ali Jinnah, Kazuyoshi Takayama
    Abstract PDF
    Numerical simulation of the effect of turbulence strength on shock/turbulence interaction
    Mohammad Ali Jinnah, Kazuyoshi Takayama

    Abstract

    Shock wave interactions with different strengths of turbulence are observed numerically by solving the time-dependent three- dimensional Navier-Stokes equations with k-z turbulence model for a compressible fluid. Numerical measurements are taken before and after the interaction of the reflected shock wave with different turbulent regions located along the longitudinal distance behind the turbulence-generating grids in the shock tube. All turbulent fluctuations are measured for the shock wave interaction with the turbulence of different strengths and it is observed that the longitudinal turbulence intensity and turbulent kinetic energy level are amplified and the amplification is higher in interaction of shock wave with comparatively weak turbulence. Due to stronger compressibility effects on the turbulent field, all length scales are decreased more after the shock/turbulence interaction. After the shock/turbulence interaction, the dissipation rate of turbulent kinetic energy decreases in all the cases of the strength of turbulent fields and the decreasing of the dissipation rate is higher for the stronger turbulence field.
  • Automatic Generation Control with Fuzzy- Proportional Integral Controller in an Isolated Power System Considering Governor Nonlinearity
    M. F. Hossain, T. Takahashi, M.G. Rabbani
    Abstract PDF
    Automatic Generation Control with Fuzzy- Proportional Integral Controller in an Isolated Power System Considering Governor Nonlinearity
    M. F. Hossain, T. Takahashi, M.G. Rabbani

    Abstract

    This paper presents the implementation of Fuzzy-Proportional Integral controller (FPIC) for controlling automatic generation control (AGC) in electric power generation systems. A typical single area power system is considered with governor nonlinearity. As a consequence of continually load variation, the frequency of the power system changes over time. In conventional studies, frequency transients are minimized by using conventional proportional integral (PI) controllers aiming of secondary control in AGC and zero steady-state error is obtained after sufficient delay time. In this paper, instead of this method, the configurations of FPIC controller is proposed. In this paper, fuzzy logic control is used to tune the output of the conventional PI controller for getting better performance. For any load changes, the proposed controller restores the frequency to its nominal value within the shortest possible time. This controller provides a satisfactory balance between frequency overshoot and transient oscillations with zero steady-state error. All the results of the proposed controller are compared with conventional PI controller in both cases with and without governor dead-band.
  • A New Control Approach for Tomato defect sorting with Machine Vision System
    Md. Rokunuzzaman, Md. Wahedul Islam, Manukid Parnichkun
    Abstract PDF
    A New Control Approach for Tomato defect sorting with Machine Vision System
    Md. Rokunuzzaman, Md. Wahedul Islam, Manukid Parnichkun

    Abstract

    This paper describes a new approach of control for a Machine Vision System applied to sort defective tomatoes. For this purpose Matlab 7.0 is used to develop the controlling algorithm. This approach is new because usually control is done by C programming. But for Modern Operating Systems like Windows XP and 2000 it is difficult to use C program directly for control. So this paper introduces a new technique of controlling a Machine Vision System for sorting of tomatoes using data acquisition toolbox of Matlab 7.0. In this system parallel port is programmed to control the defect sorter through a simple interfacing circuitry. The performance of the defect sorting through the control system has been found to be 5 tomatoes/sec, which is economic in automatic fruit sorting and detection process.
  • CLASSROOM CULTURE OF THE FEMALE TEACHERS IN POLYTECHNIC INSTITUTES OF BANGLADESH: A QUALITATIVE & QUANTITATIVE ANALYSIS
    Shamim Ahmed
    Abstract PDF
    CLASSROOM CULTURE OF THE FEMALE TEACHERS IN POLYTECHNIC INSTITUTES OF BANGLADESH: A QUALITATIVE & QUANTITATIVE ANALYSIS
    Shamim Ahmed

    Abstract

    Classroom is considered as the obvious place to occur learning and classroom activities play a great role in teaching- learning. This study was conducted in the polytechnic institutes of Bangladesh and the principal aim was to investigate the classroom culture of the female teachers of the polytechnic institutes. For the convenience of data collection 7 out of 43 government polytechnics were purposively taken as sample. The data were collected by the author himself with an observation schedule and through informal interviews with the students and the female teachers. It was found from the study that in most cases the classroom environment of the female teachers was not participatory though female teachers exhibited a very good teacher-student rapport. From the study it was recommended that, the female teachers should be well trained and be provided with modern books and Internet facilities. Besides, their teaching load should be reduced to a satisfactory level, and they should also be motivated by providing promotion on time.