Experimental and numerical investigations have been performed to study the natural convection heat transfer from a vertical rectangular fin arrays at different orientation angles.An experimental setup was constructed and calibrated to test different fin configurations. It basically consists of base plate, an array of parallel longitudinal fins, heating unit and layers of thermal insulation. Fin length (L) and fin thickness (t) were kept fixed at 187 and 6.5 mm respectively, while fin spacing (S) was varied from 3 to 16 mm and fin height (H) was varied from 15 to 45 mm. The orientation angle (β) was changed from 0° to 60°, and temperature difference between fin and surrounding (∆T) from 30 to 95 o C.Base-to-ambient temperature difference was also varied through a calibrated wattmeter ranging from 10 to 180W. To understand the general flow patterns dominating flows from the heat sink, the three-dimensionless elliptic governing equations were solved using finite volume computational fluid dynamics (CFD) code. A comparative study between the experimental and numerical results was performed to verify the numerical code. It was found for the configuration tested that the heat transfer rate per unit base area increases with the increase in the fin spacing and reaches a maximum value then decreases with farther increase in the fin spacing. The maximum heat dissipation occurs at optimal spacing S opt =7 mm. Empirical correlations between Nussult number, Rayleigh number, fin spacing, fin height, orientation angle, temperature difference between the fin and surroundings were derived. Finally the present work general empirical formula is given in the form =. .. .. Where , 15 mm ≤ H ≤ 45 mm, 3mm ≤ S ≤ 16 mm, °0 ≤ β ≤°60, t = 6.5 mm, L = 187 mm.

Prosopis farcta (Banks & Sol.) J. F. Macbr. has been reported for the first time from Libya. This species is native in Asia. Flowering specimens of Prosopis farcta collected from Sokna Region about 650 Km south-east Tripoli. It is presented with updated nomenclature, taxonomic description, geographical distribution, place of occurrence in Libya, and field colored photographs are also provided. The voucher specimens were deposited in the Herbarium of Botany Department (ULT), University of , Tripoli, Libya.

التحول من منظمة الوحدة الأفريقية إلى الاتحاد الأفريقي. هل يحدث ذلك فرقًا؟

يحلل المقال المنظمات الدولية مثل (عصبة الأمم) التي أنشئت في عام 1919م و الأمم المتحدة في عام 1945م وكذلك المنظمات الإقليمية مثل منظمة الدول الأمريكية (1948)، جامعة الدول العربية (1949)، منظمة حلف شمال الأطلسي، الناتو (1949)، منظمة معاهدة وارسو (1955) منظمة التعاون الاقتصادي و التنمية OECD) (1961))، منظمة الوحدة الأفريقية OAU) (1963))، رابطة أمم جنوب شرق آسيا (1967) (ASEAN) و الاتحاد الأوروبي (1957) (EU) ويقيم دورها في تحقيق السلام والأمن، وكذلك توفير الرفاهية والاستقرار الاقتصادي في جميع أنحاء العالم. 

A novel non-blind audio watermarking algorithm, using chirp z-transform in combination with discrete wavelet transform and singular value decomposition, is presented in this paper. In the proposed method, a watermark audio signal (about 13 seconds in length) is hidden into an original audio signal (about 51 seconds in length) by applying discrete wavelet transform, chirp z-transform, and singular value decomposition. The effectiveness of the proposed algorithm has been tested using signal-to-noise ratio, objective difference grade (ODG), and normalised cross- correlation of watermarked audio signal under various common audio attacks. Experimental results demonstrate that the algorithm has a high capacity (352.8 kbps), without significant perceptual distortion (ODG > -0.29) and provides good robustness against common audio attacks, including: re-sampling, echo addition, MP3 compression, additive white Gaussian noise, re- quantisation, cutting, and low-pass filtering. This algorithm has a high capacity and excellent audio quality compared with other audio watermarking algorithms.