A B S T R A C T

Swirl stabilised combustion is one of the most successful technologies for flame stabilisation in gas turbine combustors. Lean premixed combustion systems allow the reduction of NOx coupled with fair flame stability. The swirl mechanism produces an aerodynamic region known as central recirculation zone (CRZ) providing a low velocity

region where the flame speed matches the flow velocity, thus anchoring the flame whilst serving to recycle heat and active chemical species to the root of the former. Another beneficial feature of the CRZ is the enhancement of the mixing in and around this region. However, the mixing and stabilisation processes inside of this zone have shown to be extremely complex. The level of swirl, burner outlet configuration and combustor expansion are very important variables that define the features of the CRZ. The complex fluid dynamics and lean conditions pose a problem for stabilization of the flame. The

problem is even more acute when alternative fuels are used for flexible operation.

Therefore, in this paper swirling flame dynamics are investigated using computational fluid dynamics (CFD) with commercial software (ANSYS). A new generic swirl burner operated under lean-premixed conditions was modelled. A variety of nozzles were analysed using isothermal case to recognize the the behavers of swirl.

The investigation was based on recognising the size and strength of the central recirculation zones. The dimensions and turbulence of the Central Recirculation Zone were measured and correlated to previous experiments. The results show how the strength and size of the recirculation zone are highly influenced by both the shear layer surrounding the Central

Recirculation Zones (CRZ) and outlet configurations.

Corruption is widespread in different regions in the world and exists in all countries, both

developed and undeveloped, in the public and private sectors. Just the rate of corruption is

different from one country to another. Corruption is a very important issue in the world today,

and it is very important to understand causes of corruption across the nations. Thus, corruption

has occupied minds of thinkers on different levels both political and economic. It can be a major

obstacle in the process of economic development. Hence, corruption has negative impacts on the

economic growth in any country that suffers from it. Thinkers seek different ways to diagnose

reasons for corruption, and they try to find a panacea to this problem because corruption impedes

the development of countries.

This research paper was motivated by the observation that exams are the main (if not the sole) method of assessment in the postgraduate programs in the English departments in the University of Zawia and the Libyan Academy. The aim was investigating and experimenting the use of assignment as another method of assessing students’ achievement.

To fulfill this aim, the researcher taught the students in the two English departments separately and simultaneously one of the subjects, namely ELT Methodology. Instead of giving them a typical midterm exam, students were asked to do an assignment in which they evaluate the suitability of some textbooks in teaching and learning English as a foreign language and adapt these books to be suitable for the Libyan context. The same students were given a formal and final exam at the end of the course. The comparison of the scores of the two assessment methods has shown that students did better in the assignment than in the exam. This has supported the results of the questionnaire which was given to the same students. These results indicated that half of the students preferred using assignments to using exams while another considerable number preferred the use of a mixture of assignments and exams. Only a few students selected exams as their preferred method of assessment.

Therefore, it is recommended that assignment as a method of assessing students achievement should be integrated into MA programs in Libyan universities and academies due to its role in improving the students’ practical skills and abilities and enhancing their understanding of the learned subjects.  

Cutting samples (n = 150) and Core samples (n = 6) from the Taouratine, Dembaba, Assedjefar Marar, Awaynat Wanin, Tanezzuft and Mamuniyat Formations ( Jurassic to Ordovician), derived from wells (A-3, B-1, H-1 and H-15), locate in the A, B and H fields, present in Murzuq Basin were analysed. Rock-Eval Pyrolysis, Total Organic Carbon and specific Aromatic Molecular Biomarker (by the use of chromatography- mass spectrometry GC-MS) as geochemical parameters implemented to investigate their Lithology, kerogen type, organic matter (OM) richness and maturity evaluation. Such Formations are fair to very good quantity of organic matter passing in the course of excellent source rocks, have average of organic carbon richness (TOC) value ranged between 0.2% to 16.7% with one anomalously rich sample at 666m (well H-1) where a dark grey shale has a TOC content of 46.1% and high potential yield over 90000 ppm. The studied rocks are ranged from immature to mature of hydrogen index (HI) ranged between 24 - 302 mg HC/g TOC versus pyrolysis Tmax, with dominance of kerogen II/III Type, resulted based on HI versus oxygen index (OI), ranged from 3 to 161 mg CO2/g TOC. The Tmax , spore colouration (SCI) and Vitrinite Reflectance (% Ro) as maturity parameters ranged among 425 - 445, 5 - 8.5 and 0.35 - 3 respectively.

Aromatic hydrocarbon ratios by use of gas chromatography - mass spectrometry pointed to two levels of thermal maturity, where the high level of thermal maturity recorded in lower Silurian, whereas the less maturity was from other formations

Mobile wireless technologies have followed different evolutionary (generation) paths aimed at unified target related to the

performance and efficiency in high mobile environment, which provides access to wide range of telecommunication services

including advanced mobile services supported by mobile and fixed networks. This paper illustrate the developments of the

mobile wireless communication, focus on the specification and capability for each technology to make an idea about the future

technology what will offer.

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