Journal of Basic and Applied Sciences  -   Volume 8 Number 2


Troubleshooting Techniques of Complex Multi-Layered PCBs

Mirza Salman Baig and Ambreen Insaf

http://dx.doi.org/10.6000/1927-5129.2012.08.02.33

Abstract: In this modern era where technology is rapidly changing and is being advanced day by day, Pakistan is dependent on foreign OEM (Original Equipment Manufacturer) for the functional supportability of the systems because most of the commercial and non-commercial systems are foreign OEM based. In the case of any defect of the systems and to reduce the dependency on OEM, the simplest way is to troubleshoot the PCBs (Printed Circuit boards) of the system locally instead of purchasing new PCB or sending it back to OEM for repair until we are able to design our own systems. Thus, it won’t be wrong saying “time, tide and technology wait for none”. The purpose of this research is to achieve self-reliance in PCB troubleshooting, thereby reducing dependability on foreign OEMs, equipment downtime and high costs being acquired in PCB repairs, secondly to highlight the importance of this field so that universities may adopt it as a subject. This research paper is based on some troubleshooting techniques for repair of complex multilayered PCBs.

Keywords: Technology, functional supportability, foreign Original Equipment Manufacturer, commercial systems, repair of Printed Circuit Board.

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The Effect of Grain Size on Radon Exhalation Rate in Soil Samples of Dera Ismail Khan in Pakistan

Tabassum Nasir and Nisar Ahmad

http://dx.doi.org/10.6000/1927-5129.2012.08.02.29

Abstract: Radon concentration and its exhalation rate has been measured from twenty five soil samples collected from seven different locations of Dera Ismail Khan, in the north west of Pakistan. These samples were crushed after drying and passed through sieves with different sizes of pores to get three grain sizes, £0.595 mm, 0.595-2.00 mm and 2.00-4.00 mm of soil. CR-39 based NRPB (National Radiological Protection Board) radon dosimeters have been used to measure the radon concentration and exhalation rates. The maximum average value of radon exhalation rate has found to be: (3.57±0.38) Bq m-2 hr-1 in the samples having grain size 2.00-4.00 mm and the minimum as: (2.21±0.26) Bq m-2 hr-1, in the samples with grain size £ 0.0595 mm. This indicates that the radon exhalation rate increases with the grain size. The maximum average value of radon exhalation rate has been found in samples collected from river side where soil texture is silty clay loam. The obtained values of radon exhalation rate for all the samples are well below the world average value of 57.60 Bq m-2 hr-1.

Keywords: Radon concentration, Radon exhalation rate, grain size, soil texture.

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