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The objectives of this research were to develop a reconstruction capability using the Program to Optimize Simulated Trajectories II (POST2), apply this capability to reconstruct the Huygens Titan probe entry, descent, and landing (EDL) trajectory, evaluate the newly developed POST2 reconstruction module, analyze the reconstructed trajectory, and assess the pre-flight simulation models used for Huygens EDL simulation. An extended Kalman filter (EKF) module was developed and integrated into POST2 to enable trajectory reconstruction (especially when using POST2-based mission specific simulations). Several validation cases, ranging from a single, constant parameter estimate to multivariable estimation cases similar to an actual mission flight, were executed to test the POST2 reconstruction module. Trajectory reconstruction of the Huygens entry probe at Titan was accomplished using accelerometer measurements taken during flight to adjust an estimated state (e.g., position, velocity, parachute drag, wind velocity, etc.) in a POST2-based simulation developed to support EDL analyses and design prior to entry. Although the main emphasis of the trajectory reconstruction was to evaluate models used in the NASA pre-entry trajectory simulation, the resulting reconstructed trajectory was also assessed to provide an independent evaluation of the ESA result. Major findings from this analysis include: Altitude profiles from this analysis agree well with other NASA and ESA results but not with Radar data, whereas a scale factor of about 0.93 would bring the radar measurements into compliance with these results; entry capsule aerodynamics predictions (axial component only) were well within 3-[sigma] bounds established pre-flight for most of the entry when compared to reconstructed values; Main parachute drag of 9% to 19% above ESA model was determined from the reconstructed trajectory; based on the tilt sensor and accelerometer data, the conclusion from this assessment was that the probe was tilted about 10 degrees during the Drogue parachute phase.

Abstract Surface water and sediment samples collected from Jukskei River in South Africa, were subjected to different extraction techniques, liquid–liquid (LLE), solidphase extraction (SPE), activated carbon extraction (ACE) and soxhlet extraction (SE) for sediment. The samples were extracted with dichloromethane, cleaned in a silica gel column and the extracts quantified using a Varian 3800 GC-ECD. The percentage recovery test for 2,40DDT, DDE and DDD and 4,40DDT, DDE and DDD in water ranged from 80%–96% and 76%–95% (LLE); 56%–76% and 56%–70% (SPE) and 75%–84% (ACE), respectively; while that recoveries for sediment samples varied from 65%– 95% for 2,40DDT, DDE and DDD and 80%–91% for 4,40DDT, DDE and DDD. The high recoveries exhibited by ACE compared very well with LLE and SE. This was not the case with SPE which exhibited the lowest value of recoveries for both 2,4 and 4,40DDD, DDE and DDT standard samples. The mean concentrations of DDT and metabolites ranged from nd-1.10 lg/L, nd-0.80 lg/L, nd- 1.21 lg/L and 1.92 lg/L for LLE, SPE, ACE and SE, respectively. The total DDT (2,40 and 4,40-DDT) in water and sediment samples ranged from 1.20–3.25 lg/L and 1.82–5.24 lg/L, respectively. The low concentrations of the DDT metabolites obtained in the present study may suggest a recent contamination of the river by DDT.

The viability of using pulsed laser excited Raman spectroscopy as a method for diamond detection from ore, has been investigated. In this method the spontaneous Stokes Raman signal is used as indicator of diamond, and a dual channel system is necessary for correcting for fluorescence of minerals and diamond itself. Various pulsed laser wavelengths from 266 to 1064nm were used, as well as cw lasers for comparison. Wavelength scans of the regions of interest, indicated that pulsed lasers at 532, 355 and 308nm may be used with confidence for this purpose. Mineral fluorescence did not appear to pose a threat to the method, but rather own fluorescence of some types of diamonds. In this respect, pulsed lasers offer a decided advantage above cw, due to nonlinear increase of fluorescence with laser power, resulting in superior Raman to fluorescence signal ratios. An apparatus constructed for discriminating diamond from ore was evaluated, and using minerals commonly occurring in diamond carrying ore as well as a wide variety of diamonds, it proved to function effectively. A significant improvement in the capability for diamond detection was found when pulsed lasers at 532 and 308nm were used, in comparison to the 532nm cw laser.

The viability of using pulsed laser excited Raman spectroscopy as a method for diamond detection from ore, has been investigated. In this method the spontaneous Stokes Raman signal is used as indicator of diamond, and a dual channel system is necessary for correcting for fluorescence of minerals and diamond itself. Various pulsed laser wavelengths from 266 to 1064nm were used, as well as cw lasers for comparison. Wavelength scans of the regions of interest, indicated that pulsed lasers at 532, 355 and 308nm may be used with confidence for this purpose. Mineral fluorescence did not appear to pose a threat to the method, but rather own fluorescence of some types of diamonds. In this respect, pulsed lasers offer a decided advantage above cw, due to nonlinear increase of fluorescence with laser power, resulting in superior Raman to fluorescence signal ratios. An apparatus constructed for discriminating diamond from ore was evaluated, and using minerals commonly occurring in diamond carrying ore as well as a wide variety of diamonds, it proved to function effectively. A significant improvement in the capability for diamond detection was found when pulsed lasers at 532 and 308nm were used, in comparison to the 532nm cw laser.

This thesis presents the findings of a study that investigated the teaching and learning of English in female government schools in the United Arab Emirates. The research was conducted by means of qualitative methods and 61 participants participated in the interviews. The research sample represents the three main parties that are directly concerned with teaching and learning English and they are: schoolteachers, school graduates, and higher education teachers. The investigation reveals three main aspects of English language teaching and learning at school. First, schoolteachers use ineffective grammar-translation methods with some principles from the direct and communicative methods. Second, school graduates have negative perceptions of English language teaching at schools and blame it on their failure to learn the language. Finally, tertiary institutions receive school graduates with poor English. There are a number of factors that affect teachers' performance in the English class. First, the syllabus is prescriptive and there is a heavy emphasis on textbooks and exams. Second, teachers operate according to a given scheme, which prioritizes high success rates in English as a school subject, and de-emphasizes English as a medium of communication. This has led to restricting teachers' autonomy and causing stagnation in the process of learning English. Also due to teachers' beliefs and other overwhelming circumstances, they resorted to the transmission model to deliver information to exam takers rather than language learners. The abovementioned conditions reflect negatively on students' attitudes, motivation, and learning style. However, they cling to a small amount of instrumental motivation that energizes them to study for the exam. Although many students are aware of the importance of English, they are not given an opportunity to learn it appropriately, which lowers their motivation substantially. Additionally, the English classroom lacks a humane classroom environment.

The Scottish vitrified forts form a unique assemblage of archaeological monuments exhibiting the common feature of partly melted masonry generally found in the vicinity of a ruined wall. Although they have received considerable attention from scholars since their discovery in the late eighteenth century many questions relating to origins, purpose and chronology remain unanswered. This work represents the first coherent attempt to develop and apply direct dating to vitrified rocks _ using thermoluminescence (TL) techniques to establish the time elapsed since the last heating of the sample. The technique is based on equating the thermoluminescence acquired by minerals within vitrified rocks, during the period following vitrification, to the levels of natural ionising radiation within and around the samples. Study sites were selected on the basis of a mineralogical, analytical and dosimetric survey of material from museum collections, and sampled from secure contexts using a portable diamond coring tool. Radiation dose rates to the samples were determined using a combination of thermoluminescence and low level counting methods coupled to standard microdosimetric models for specific mineral phases. A promising new method of rapid beta dose rate measurement was developed during this work. Thermoluminescence measurements of separated mineral extracts were performed using computerised eqUipment to determine the total radiation dose experienced since firing. Particular attention was paid to the form of the radiation dose dependence of samples from different Sites, and to the stability and reproducibility of TL signals. Coherent thermoluminescence ages were obtained from the sites of Finavon,Craig Phadrig, Dun Lagaidh, Langwell, Knockfarrel and Tap 0 Noth, using feldspar fractions extracted from the samples, and indicate a long time span for the monuments stretching from the 2nd millenium Be to the first millenium AD. This evidence considerably extends the timespan attributable to the monuments and paves the way for further work to establish the relationship between the morphology and chronology of a wider range of sites.

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