Cognitive radio technology is used to improve spectrum efficiency by having the cognitive radios act as secondary users to access primary frequency bands when they are not currently being used. In general conditions, cognitive secondary users are mobile nodes powered by battery and consuming power is one of the most important problem that facing cognitive networks; therefore, the power consumption is considered as a main constraint. In this paper, we study the performance of cognitive radio networks considering the sensing parameters as well as power constraint. The power constraint is integrated into the objective function named power efficiency which is a combination of the main system parameters of the cognitive network. We prove the exi

This paper is devoted to the discussion the relationships of connectedness between some types of graphs (resp. digraph) and Gm-closure spaces by using graph closure operators.

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

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

A new spectrophotometric method for the determination of allopurinol drug was investigated. The proposed method was based on the reaction of the intended drug with catechol and Fe(II) to form a blue soluble complex which was measured at λmax 580 nm. A graph of absorbance versus concentration shown that Beer’s law was obeyed over the concentration range of 2–10 μg ml–1 with molar absorptivity of 9.4 x 103 l mol–1 cm–1 and Sandell sensitivity of 1.4 x 10–2 μg cm–2. A recovery percentage of 100% with RSD of 1.0%–1.3% was obtained. The proposed method was applied successfully for the determination of allopurinol drug in tablets with a good accuracy and

Knowledge and awareness towards cryptosporidiosis were assessed in this study during the period from April 2009 till June 2011, among 188 person of both gender which were divided in different groups and sub groups as following Group 1: include 48 physician from different hospitals and primary health care centers in Baghdad this group were sub divided into 30 Specialist doctors and 18 General practitioners doctors. Group 2 : include 45 teaching staff member from Biology department , Biotechnology department in University of Baghdad and AL-Nahrain University as well as teaching staff member from the college of medicine – University of Baghdad and University of Mustansiryah, this group were sub divided into 9 Ph.D and 36 M.Sc. + B.Sc. me

WA Shukur, journal of the college of basic education, 2011 The aim of this research is designing and implementing proposed steganographic method. The proposed steganographic method don’t use a specific type of digital media as a cover but it can use all types of digital media such as audio, all types of images, video and all types of files as a cover with the same of security, accuracy and quality of original data, considering that the size of embedded data must be smaller than the size of a cover. The proposed steganographic method hides embedded data at digital media without any changing and affecting the quality of the cover data. This means, the difference rate between cover before hiding operation and stego is zero. The proposed steg

BN Rashid, Ajes: Asian Journal of English Studies, 2013

WA Shukur, FA Abdullatif, Ibn Al-Haitham Journal For Pure and Applied Sciences, 2011 With wide spread of internet, and increase the price of information, steganography become very important to communication. Over many years used different types of digital cover to hide information as a cover channel, image from important digital cover used in steganography because widely use in internet without suspicious.

The aim of this study is to determine the organic and inorganic components of bile and gallstones in Iraqi patients. Forty seven patients were included in this study with mean age (53+7) years and BMI (30.82+4.18) Kg/m2. Bile was classified according to its corresponding stones into: Bile of Mixed stones and Bile of pigment stones. IR spectra were studied for both types of stones and their bile in addition to biochemical analysis for organic and inorganic components. The organic components include: (cholesterol, bilirubin, bile salts, and phospholipids), while inorganic components include salts of: (calcium, phosphorus, iron, cupper and magnesium). The results reveal to there was significant low levels (p<0.005) of bile salts and phospholi