The present paper involves a detailed evaluation of specific steroid biomarkers by gas chromatography– mass spectrometry (GC–MS) and GC-metastable reaction monitoring (MRM) analyses of several crude oils and source rocks from the East Sirte Basin. 24-Norcholestanes, dinosteranes, 4a-methyl-24-ethylcholestanes and triaromatic steroids have been identified in both source-rocks and crude oils of the East Sirte Basin. Diatoms, dinoflagellates (including those potentially associated with corals) and/or their direct ancestors are amongst the proposed sources of these biomarkers. These biomarker parameters have been used to establish a Mesozoic oil–source correlation of the East Sirte Basin. Hydropyrolysis of an extant coral extract revealed a similar distribution (although immature) of dinosteranes and 4a-methyl-24-ethylcholestanes also observed in the Sirte oils and source-rocks. This is consistent with the presence of dinoflagellates present during the deposition of the Mesozoic aged East Sirte Basin Formations. A good data correlation for the rock extracts revealed a similar distribution of 3,24-dimethyl triaromatic steroids, 3-methyl-24-ethylcholestanes, 4-methyl-24-ethylcholestanes and 2-methyl-24-ethylcholestanes observed in one of the oil families and associated source-rocks for the East Sirte Basin.

A numerical simulation of a two-stage reciprocating compressor has replicated the operations of the compressor under various conditions for the development of diagnostic features for predictive condition monitoring. The simulation involves the development of a mathematical model of five different physical processes: speed–torque characteristics of an induction motor, cylinder pressure variation, crankshaft rotational motion, flow characteristics through valves and vibration of the valve plates. Modelling both valve leakage and valve spring deterioration has also been achieved. The simulation was implemented in a MATLAB environment for an efficient numerical solution and ease of result presentation. For normal operating conditions, the simulated results are in good agreement with the test results for cylinder pressure waveforms and crankshaft instantaneous angular speed (IAS). It has been found that both the IAS 

Historically, applications for traditional phenolic resin/polyurethane materials are limited due to the inherently weak thermal stability of urethane-phenolic linkage and slow reaction rate. A novel concept has been developed to produce phenolic resin/polyurethane copolymers ...

The unique features of polybenzoxazines make them attractive for a wide range of applications. The characteristics of polybenzoxazines such as excellent dimensional stability, lower surface energy, higher Tg, and lower moisture absorption are attributed to the stable intramolecular hydrogen bonding in their network structure. The features make polybenzoxazines excellent candidates for the applications that require near zero shrinkage and high dimensional stability. Polybenzoxazines are formed by the autocatalytic polymerization of benzoxazine monomers. Polybenzoxazines are well known as a new class of thermoset polymers used for high performance applications. They provide the characteristic properties found in phenolic resins, such as high thermal stability, excellent electrical properties, good mechanical properties, and better flame retardancy. Furthermore, they have the advantages …

 This study is a comparison between English and Arabic vowels. First a description and classification of vowels in the two languages is given. Then the two sets of vowels are contrasted to find which vowels are similar and which are not. Finally, the set of similar sounds are analysed acoustically to find out to what extent they are similar. This is done by recording two sets of words containing these vowels and measuring their formants and duration. The findings show that although these sounds are similar in some aspects, Arab learners of English do not replace English vowels with their Arabic counterparts but, instead they try to reach the target sounds even though they are not completely successful in achieving their goal. 

In the introduction of this paper the aims, the subject and its importance are briefly stated. However, the paper consists of two main parts. The first part deals with the segmental phonology of Tripolitanian Arabic and this includes classification of both vowels and consonants and relevant features such allophonic variation, length, geminating and clusters. The second part, on the other hand, deals with the suprasegmental level of the dialect and in which its syllable structure and stress pattern are discussed. In the conclusion, the findings of the research are summarised and some recommendations for further research are given. 

Hydrodesulfurization (HDS) and Hydrodearomatization (HDA) of a real Straight Run Gas Oil (SRGO) were investigated over CoMo–S sulfide catalyst in a high–pressure fixed–bed integral reactor. The effect of the key process parameters on the quality of product was studied by varying the temperature (200–370°C), pressure (20 to 50 bar) and space velocity (1 to 4.7h-1). Experimental results revealed that HDS,% activity improved up to 81% when the temperature was increased up to 370°C but reduced to 60% with increase of space velocity up to 4.7 h-1. It has been also found that the rate of HDA, % activity enhanced up to 40.6% by increasing pressure up to 50 bar. The Cetane index underwent an increase of 1–3 degrees and gravity increased by 1–1.7° API. The implication of these results on refining industry is that mild hydrotreating of diesel fuels using the single–stage technology will not enable local refineries to produce diesel fuel meeting the current specifications (<15 ppmwt) except with severe/deep once–through desulfurization or two–stage once–through desulfurization with or without splitting the first reactor effluent. Key words: Diesel fuel; hydrodesulfurization; hydrodearomatization; CO–MO–S/ Al2O3 catalyst

 Abstract: The paper presents an adaptive intelligent control method to overcome effects of some indeterminate and undealt factors that a DC .drive is suffered. In the speed loop, we use a three-layer neural networks through a backpropagation (BP) algorithm out of line learning to realize the fuzzy-control tactics. We use unit neuron through Hebb algorithm on-line dynamic learning to realize adaptive mechanism. The simulation is based on a MATLAB6.0 neural networks toolbox with simulink. The results of the simulation show that adaptive intelligent control method enables the system to have good dynamic and stability performance. The proposed method develops the use of simulink in the field of electrical drive of adaptive intelligent control.