STEADY-STATE BEHAVIOUR OF A DOUBLE-CAGE INDUCTION MOTOR

Experimental determination of parameters of a doable-cage equivalent circuit and prediction of the separate steady-state inner and outer-cage rotor torques is discussed for the first time. In future this could help in the verification of design parameters & understanding and improvement of the motor. The author also discusses the effect of variation of stator leakage reactance and mutual reactance between the cages on rotor side parameters and overall performance of the motor. The variation of curves for individual cage torques is similar to their total torques which is itself very close to the torques claimed by the manufacturers on their design sheet data

ENVIRONMENTAL HAZARDS IN THE DEVELOPING WORLD, A SAMPLE STUDY OF PAKISTAN: ASSESSMENTS, IMPACTS AND PLANS

Centralized planning policies and lack of democratic participation of the masses at community level have not only created uneven and unsustainable development and rural-urban bias, but have also generated various issues of water, air and land pollution, effecting adversely human development in the developing world in general but in Pakistan in particular. INDEXIN

PERFORMANCE OF SOLAR FRUIT DRYING SYSTEM

A considerable amount of fresh fruits produced in Pakistan are wasted every year due to non-availability of basic postharvest technologies. To overcome this problem a solar fruit drying system was designed and developed at Farm Machinery Institute (FMI), Islamabad. The system consists of six flat plate solar collectors, an axial flow fan, and a drying chamber. The performance of the system was evaluated at Nalkot, Swat, where the persimmon was available in enough quantity for drying.It was observed that the solar collectors were capable to raise the average daily temperature of the ambient air from 26°C to 44°C, however, the hot air within the drying chamber was not distributed uniformly. The average daily efficiency of the solar collectors was 44%. The solar dryer was capable to process about 1 to 1.5 tonnes of fresh persimmon in one month, whereas farmers wanted to increase its drying capacity up to 4 to 5 tonnes / month. It was concluded to redesign the drying chamber, and to provide a supplement source of heat (gas or oil fired) to solar dryer in order to increase its drying capacity

THE COMPLEXES OF URBANIZATION IN SOUTH ASIA: ASSESSMENTS, IMPACTS, PLANS AND PROSPECTS FOR INTERNATIONAL COLLABORATION

Centralized planning policies, lack of democratic participation of the masses in socio-economic activities at community levels, poor legislation and growing share of defense in the annual budget, have not only created rural-urban bias, uneven and unsustainable development but have also generated the problems of mass poverty, unemployment, scarcity of socio-economic services, pollution of water, air and land, and also rising slums and squatter in urban localities, affecting adversely human development in South Asian Countries

FIELD EVALUATION OF LOCALLY DEVELOPED MECHANICAL RICE TRANSPLANTER

Heavy Mechanical Complex, Taxila in Collaboration with Farm Machinery Institute, NARC, Islamabad manufactured four units of mechanical rice transplanter in 1999. One of these units was evaluated during the rice transplanting season of 1999. This paper presents the working performance, accuracy, and reliability of the locally developed machine. The effective field capacity of the machine was 0.16 ha/hr, and the field efficiency was 43% during these field tests. The missed hills were observed to be 20%. The reasons for low field capacity and higher percentage of missing hills were that more time lost for machine adjustments and nursery was not grown properly. A few parts of the locally developed rice transplanter were identified in order to improve their reliability. Finally, it was concluded that perfection is required in this technology, before its commercialisation at large scale

SYNTHETIC APERTURE RADAR: PRINCIPLES AND APPLICATIONS

In this paper an introduction to synthetic aperture radar is presented. Synthetic aperture radar is a relatively new remote sensing platform and the technology has matured a lot in the last two decades. This paper introduces the concepts behind SAR principles as well as the major areas where this new technology has shown additional information