In this paper, we use concepts and results from percolation theory to investigate and characterize the effects of multi-channels on the connectivity of Dynamic Spectrum Access networks. In particular, we focus on the scenario where the secondary nodes have plenty of vacant channels to choose from-a phenomenon which we define as channel abundance. To cope with the existence of multi-channels, we use two types of rendezvous protocols: naive ones which do not guarantee a common channel and advanced ones which do. We show that, with more channel abundance, even with the use of either type of rendezvous protocol, it becomes difficult for two nodes to agree on a common channel, thereby potentially remaining invisible to each other. We model this

Energy is one of the components of the national security of countries and is of particular importance to the industrialized countries, including Germany. Energy policy includes many areas and has an impact on various sectors such as the environment, climate, agriculture and others. During the past few years, Germany has witnessed many transformations, the most important of which is the energy transition towards renewable energy, and it was strengthened in the strategy that was It was developed in 2010, which aims to achieve a long-term energy transformation, and sales of the German energy technology sector have evolved from 2010 to 2020, and this issue is related on the other hand to the concept of energy security and because of its strateg

Precarity means the lack of social and economic networks; a considerable exposure to danger and harm. Minority groups are precariat for they lack rights and full citizenship. Precarity is related, states Judith Butler, with the individual’s performativity, and his ability to perform his gender role. Toni Morrison continually goes to past to retell the history of African Americans. The issues of race, gender and national identity are recurrent in her work. Reading her book Home (2012) evokes the idea of precarity and performativity since the two main characters, Frank and Cee are precarious characters that fail to perform their gender role properly, and eventually are exposed to hazard and harm. This research displays how African American

This research is the subject of "Domination and Motivation in the Sculptures of Mona the Saudi" to the study of an accomplished Arab sculptor with its varied sculptural activity between the works of the exhibition and the works of the squares, as well as its distinguished place among the contemporary Arab sculptors. This research is divided into four chapters:

     The first chapter deals with the general methodological framework of the research in terms of the research problem which is focused on the question: What is the hegemony and motivation in the sculptures of Mona Saudi? The importance of research and the need for it, including the technical scientific material concerned with the sculptural achievement of t

Diesel generators is widely used in Iraq for the purpose of maintaining electric power demand. Large number of operators engaged in this work encounters high level of noise generated by back pack type diesel generators used for this purpose. High level of noise exposure gives different kinds of ill effect on human operators. Exact nature of deteriorated work performance is not known., in present research , quastionaire was adsministered 86 repondents in Baghdad city were exposured to wide range of noise level (80-110) dB(A) with different ages and they have different skill discretion levels. Noise levels A-weigthed decibles dB(A) were measured over 8 weeks two times aday during the 2019 summer using a sound level meter.For predicting the wo

In this paper, method of steganography in Audio is introduced for hiding secret data in audio media file (WAV). Hiding in audio becomes a challenging discipline, since the Human Auditory System is extremely sensitive. The proposed method is to embed the secret text message in frequency domain of audio file. The proposed method contained two stages: the first embedding phase and the second extraction phase. In embedding phase the audio file transformed from time domain to frequency domain using 1-level linear wavelet decomposition technique and only high frequency is used for hiding secreted message. The text message encrypted using Data Encryption Standard (DES) algorithm. Finally; the Least Significant bit (LSB) algorithm used to hide secr