Thermoluminescent dosimeter (TLD) is a device used to evaluate integrated dose of ionizing radiation. Natural mineral topaz as a thermoluminescent (TL) material has been studied for radiation dosimetry. The northern area of Pakistan along with Himalayas, due to its geological settings, is rich in topaz which is found in pegmatite rocks. Four mines namely: Kharguluk, Nyit, Sabser, and Yono in district Skardu were selected for sampling of topaz. Relatively big pieces of topaz were converted into chips and powder of micron size. Pellets of topaz composite with glass 1:2 wt.% and teflon 2:1 wt.% were prepared by compressing and sintering. The mineral was recognized as topaz through phase identification by XRD (X-ray diffraction). The mineral collected from Kharguluk mine was not topaz rather mixed with quartz. The elemental analysis by the XRF (X-ray fluorescence) of topaz of understudy mines resulted about 56.554, 22.030, 11.293, 9.560 and 0.453 at.% of the elements O, Si, Al, F and H. These results confirmed the mineral as topaz. The irradiation of topaz pieces with fast neutrons and thermal treatment produced deep and London blue colours in topaz. The TL response of virgin topaz of understudy mines generated a single huge peak in glow curve at temperature around 250 oC, which is the gesticulation of topaz. The INAA (Instrumental Neutron Activation Analysis) of topaz from the three mines detected the elements Na, Ga and Cs in three mines, while As and Sb were detected in Yono and Nyit mines respectively. The photoinduced emission spectra of topaz powder from three mines at the excitation wavelength 230 nm produced two bands. One band is at 430 nm and other at 470 nm which are the characteristics of topaz. The pellets of the composites were sintered at 400 to1200 oC. The TL response of the composites and [OH]/[F] ratio decreased with increasing sintering temperature. The optimum temperature selected for preparation of topaz composites was 900 oC. The effect of ultraviolet (UV) and visible light on topaz revealed that UV and visible light contribute to phototransference of charge. The TL glow curves of topaz chips, topaz-glass and topaz-teflon composites showed stable peaks (dosimetric peaks) at about 250-260, 250-260 and 257-265 oC respectively. Initially, the fading was maximum (27-30 %) and became 6-9% after few days. Chips and pellets showed the linearity with dose, good reproducibility, independent dose rate, linear dose response and strong energy dependence below 600 keV. The chips and pellets were found suitable for dosimetry for dose greater than 0.01 Gy at high energy beams. Saturation in the TL response was observed above 2000 Gy. The pellets of topaz-glass showed better mechanical stability than topaz chips and topaz-teflon pellets. The cutting of topaz chips was found difficult and time consuming, while the preparation of pellets of topaz-glass and topaz-teflon was relatively easy. Topaz-glass showed better TL dosimetric features as compared to topaz chips and topaz-teflon composites. These are recommended to be used at the facilities where high radiation doses are involved. The TL analysis of the glow curves using IRM (Initial Rise Method), Tm-Tstop, PSM (Peak Shape Method) and VHR (Variable Heating Rate) method showed that topaz and its composites with glass and teflon follow second order kinetics. The thermal activation energies 0.976- 1.576 eV for natural topaz were found to be greater than 0.488-0.627 eV for topaz- glass and 0.447-0.616 eV for topaz-teflon. The thermal activation energy found by VHR was 1.35 times higher than determined by PSM and IRM. The OSL (optical stimulated luminescence) dosimetric characteristics of the pellets of topaz-glass and topaz-teflon composites were studied for various energy beams of photons and particles using CW (continuous wave)-OSL mode. Blue light as a stimulation source for OSL generated a rapid decaying response within 10 s and then a long non-zero tail was observed. The integrated OSL (IOSL) response met the dosimetric requirements for topaz-glass and topaz-teflon at dose greater than 0.01 Gy and 1.0 mGy respectively. The TL response of topaz before and after OSL measurement showed two peaks in the glow curve at the same position. After OSL measurement, decline of about 1.35 times less in intensity of peak 2 was observed. Radiation dose was measured at IPEN, Brazil with the TLDs: LiF, topaz- chips and the composites of topaz-glass and topaz-teflon. Using the respective calibrations curves and applying the fading corrections, the measured dose proved that topaz and its composites are suitable for radiation dosimetry at high radiation areas. The price of topaz based TLDs is less than commercial dosimeters. Topaz-glass and topaz-teflon pellets can be recommended for the measurement of dose greater than 0.01 Gy by the TL method, while topaz-teflon are suitable for dose greater than 1.0 mGy using OSL read out. Further exploration of topaz from other mines of Pakistan, their TL/OSL analysis and applicability at sterilization, irradiation and medical centres is strongly recommended.
ہنجو روواں یار دی خاطر اس مدنی سرکارؐ دی خاطر قاصد بنے رسولؐ پیغمبر سوہنے اس دربار دی خاطر ظاہر ہویا جگ تے آ کے رب سوہنے دل دار دی خاطر نورِ محمد ظاہر ہویا اس دنیا گلزار دی خاطر روندے رہے وچ غار حرا دے اس امت گنہگار دی خاطر دشمن دا وی پچھنا کردے ٹُر گئے گھر بیمار دی خاطر یار بلایا عرشاں اُتّے اپنے خاص پیار دی خاطر سجدے وچوں سر نہ چایا اس حسینؑ سوار دی خاطر
The present study investigates the socio-economic problems of the labors in Brick Kilns which are situated in the vicinities of district Hyderabad (Rural). Eighty three respondents from twenty five brick kilns were selected for interview. It is found that majority of the respondents was illiterate and never visited educational, technical and religious institutions. The economic categorization of the labors revealed that majority was categorized as ‘poorest of poor’ (living below poverty line), having semi-pacca houses, earning less than 10,000 rupees per month to manage their entire family. Due to very low income they spent least amount on education and health while more on food and utilities. The general problems reported by the labors are: poor quality of drinking water, no shelter at work place, child labor, low and late payment of wages, long working hours etc. Besides these, both male and female labors informed about misbehave and use of abusive language by the owner/manager, even few of them also complained about physical abuse. Stomach problem was found as common disease in men followed by Anemia whereas in women Anemia was ranked first followed by Backache.
Subspace based algorithms belong to one of the most explored face recognition algorithm categories which follow a holistic approach for feature extraction. These methods operate directly on the pixel intensities of a facial image and extract features. The basic trait of these algorithms is that they reduce dimensionality to reduce the computational complexity of feature extraction while keeping the statistical separation between different classes. Therefore these algorithms are the economical choice for feature extraction. These algorithms are based on the key concept that most of the information in a facial image is highly redundant and that the discriminating features reside in a subspace of the face image. Therefore these algorithms aim to extract these features by reducing the redundant and non-discriminating information. The choice of a classifier is the key factor in designing an efficient pattern classification system. This choice very closely relates to the data on which it is going to be applied. Another important issue is the irrelevancy in reported results of different classifiers. The evaluation criterion which is set for evaluating a specific classifier plays a significant role in determining the true potential of a proposed classifier. There is a need to evaluate these reported classifiers using the same evaluation criterion to judge the suitability of each classifier for a specific imaging condition. For face recognition, a surfeit of classifiers has been proposed to date but none of them alone is capable enough to cater with all the inherent variations of the facial image data. Therefore there is a need to explore combinations of classifiers known as ensemble classifiers. As different classifiers extract complementary features of the object to be classified, therefore combining the properties of individual classifiers in an ensemble classifier does result in increased classification accuracy. The overall suitability of this ensemble classifier depends on the memory and computational complexities of the constituent base classifiers. VI In this thesis, a newly reported and highly cited face recognition algorithm Laplacianfaces is initially explored for its true potential by varying its internal and external parameters for different face recognition tasks. Based on the outcome of this initial analysis, other famous subspace face recognition algorithms are also evaluated by using distance metrics both from the image space and mahalanobis space. This evaluation was performed by using the evaluation methodology employed in Face Recognition Vendor Tests (FRVT) and FERET evaluations. These algorithms are evaluated against various probe sets from three different and famous facial databases namely FERET, ORL and YALE. This study hence provides enough testing variables to judge the performance of algorithms against different imaging conditions or facial variations. Based on this exhaustive comparative analysis, a group of six most accurate and most economical classifiers are selected. Ensemble classifiers with combinations ranging from two to six of these best selected base classifiers are evaluated against the same testing conditions. The ensemble classifiers are constructed by combining base classifiers using two simple ensembling techniques namely re-ranking and weighted scoring approach. The average performance of this ensemble classifier also called unified classifier is found to be well ahead of that for the individual constituent base classifiers. The work reported in this study proves the effectiveness of ensemble classifiers for face recognition tasks. The results of the proposed unified classifier in comparison to the best performing subspace algorithms demonstrate that the unified classifier has a global performance and can handle different variations effectively.