In this paper we present an approach to optimistic concurrency control where the write phase occurs before the validation phase (RWV instead of RVW). Our work extends earlier research into real-time databases that utilized virtual execution to lower disk access overheads. Such work demonstrated that virtual execution allowed an increase in transactions completing before deadlines expired and improvements in overall throughput. However, we demonstrate that only with the reversal of the write and validation phases can virtual execution reach its full potential.

This paper presents a new high-capacity algorithm for audio watermarking for the purpose of embedding a watermark audio signal into an original audio signal. This algorithm uses DCT (discrete cosine transform) in combination with SVD (singular value decomposition), DWT (discrete wavelet transform), and CZT (chirp ztransform). For the purpose of ensuring high levels of imperceptibility and robustness, a low-frequency sub band of 1-level DWT is selected to embed the watermark, followed by DCT, CZT, and SVD. As a result, the proposed algorithm achieves a high capacity of 352800 bits per second while a good quality audio signal is maintained (having an objective difference grade of more than-0.04). It also provides high imperceptibility (a signal to noise ratio of more than 58 dB) and it is extremely resistant to common audio attacks, including requantizing, resampling, additive white Gaussian noise or AWGN, MP3 compression, and low-pass filtering. The proposed algorithm presents much better compared to the audio watermarking algorithms already existent.

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.

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.

A floristic survey of Sedrores Al-Qawasim mountains in Gharyan district - Libya was conducted in two consecutive growing seasons from 01/04/2018 to 01/6/2019. In this study area, a total number of 320 plant species belonging to 214 genera were collected representing 44 families, of which 39 families and 276 species belonging to dicotyledons, and 5 families and 44 species are belonging to monocotyledons. The results showed the dominance of the family Asteraceae with 60 species, followed by the family Fabaceae with 32 species, then the family Poaceae with 29 species. The results showed the dominance of the (Euphorbia genus) with 7 species, followed by Helianthenum, Plantago and Erodium with 6 species each. Moreover, life-form spectrum analysis showed the predominance of therophytes with 210, followed by Hemicryptophytes with 59 species, while chorotype spectrum analysis showed the dominance of Mediterranian species with 151 species, followed by Mediterrean/Iranu-Turanean with 72 species. 

Watermarking techniques have been considered as one of the best efficacious methods 

to solve the issues of protecting copyright due to the proliferation of digital multimedia 

information on the internet. The digital multimedia information is such as image, 

audio, and video which can today be easily copied, distributed, and modified without 

loss in fidelity. As a result, it is necessary to utilize some kind of copyright protection 

techniques to avoid illegal copying, distribution, and digital copyright modification. 

The digital watermarking techniques have engaged the researchers’ attention as a 

technique for protecting copyright in the digital multimedia information. This 

technique includes a subcategory of information-hiding technologies in which the 

ownership information is hidden into the original multimedia information without 

impacting the original multimedia information quality. Despite the advances in digital 

watermarking techniques, the main objective of many types of research in digital 

watermarking topic is to improve transparency and resistance to attacks and the present 

digital watermarking schemes are not sufficiently stable or strong against various 

attacks. This study aims to develop state-of-the-art digital watermarking techniques 

for different multimedia information through improving the imperceptibility and 

robustness to geometrical attacks and signal processing operations. Four novel robust 

blind digital watermarking schemes are introduced in this thesis for copyright 

protection of multimedia information that have not been previously introduced. The 

first robust blind digital watermarking scheme is applied for colour images utilizing 

discrete wavelet transform in combination with Walsh Hadamard transform and 

Hessenberg decomposition. The second robust blind digital watermarking scheme is 

applied for grayscale images utilizing discrete wavelet transform in combination with 

Walsh Hadamard transform and Hessenberg decomposition. The third robust blind 

digital watermarking scheme is applied for colour videos utilizing discrete wavelet 

transform in combination with Walsh Hadamard transform and Hessenberg 

decomposition. Forth robust blind digital watermarking scheme is applied for audio 

signals utilizing discrete wavelet transform in combination with Walsh Hadamard 

transform and Hessenberg decomposition. Several experiments are performed in order 

to present the effectiveness of the proposed digital watermarking schemes in terms of 

imperceptibility and robustness against attacks related to each scheme. The proposed 

digital watermarking schemes achieve good imperceptibility and robustness against 

geometrical attacks and signal processing operations. The proposed digital 

watermarking schemes have a superior performance in terms of imperceptibility and 

robustness than other reported schemes in the literature.

Keywords: Watermarking, Copyright Protection, Discrete Wavelet Transform, Walsh 

Hadamard Transform, Hessenberg Decomposition.