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 

The heterogeneous design of multi-core processors, 

such as the Cell processor, introduced new challenges in porting 

high-level languages. Our project is developing tools that hide the 

underlying details of the Cell processor and eases parallel 

programming. We present a Virtual SIMD machine (VSM) 

paradigm that can be used to parallelize array expression 

automatically. The novelty is the use of a virtual SIMD machine 

model to completely hide the underlying details required for 

programming the Cell processor. The VSM paradigm can also be 

used to develop an automatic parallelizing compiler for the Cell 

Broadband Engine (Cell BE). In this paper we give an overview 

of the VSM interface and present preliminary results that show 

the performance of our VSM and its behavior on multiple 

accelerator cores using basic arrays operations

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.

Biomarker ratios, together with stable carbon (d13C) and hydrogen (dD) isotopic compositions of individual hydrocarbons have been determined in a suite of crude oils (n = 24) from the East Sirte Basin to delineate their sources and respective thermal maturity. The crude oil samples are divided into two main families (A and B) based on differences in source inputs and thermal maturity. Using source specific parameters including pristane/phytane (Pr/Ph), hopane/sterane, dibenzothiophene/ phenanthrene (DBT/P), Pr/n-C17 and Ph/n-Cl8 ratios and the distributions of tricyclic and tetracyclic terpanes, family B oils are ascribed a marine source rock deposited under sub-oxic conditions, while family A oils have a more terrigenous source affinity. This genetic classification is supported by the stable carbon isotopic compositions (d13C) of the n-alkanes. Using biomarker maturity parameters such as the abundance of Pr and Ph relative to n-alkanes and the distribution of sterane and hopane isomers, family A oils are shown to be more thermally mature than family B oils. The contrasting maturity of the two families is supported by differences between the stable hydrogen isotopic compositions (dD) of Pr and Ph and the n-alkanes, as well as the d13C values of n-alkanes in their respective oils.