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 existence of optimal combination of parameters such that the power efficiency is maximized. Then we reformulate the objective function to incorporate the throughput. According to different constraints or degree of significance, we may put proper weight to each term so that we could obtain more preferable combination of parameters. Computer simulations have given the optimal solution curve for different weights. We can draw the conclusion that if we put more emphasis on power efficiency, the transmit power is a more critical parameter, however if throughput is more important, the effect of sensing time is significant.
Cities have witnessed great changes since the planning of the first cities. This is due to the increase in population and problems in services that affect urban security. As such, urban security is directed and affected by the nature of city planning and the types of services. Besides, the kind of services plays an imminent place in providing urban security at all levels. Other factors that influence urban security can be limited to the increase of population, economic and social changes. This leads to losing urban control. This study will explore the historical chronology to identify weaknesses in urban planning since its dawn and reaching solutions to protect urban security. The importance of the research lies in achieving urban securi
... Show MoreBackground: Day case surgery has become widely accepted as a safe alternative to the inpatient care in up to 70% of the cases at a children’s hospital. It has the advantage of minimizing the psychological trauma of hospitalization, decreasing nosocomial infection, less costly and frees up hospital beds.Objectives: To assess the advantages and disadvantages of this type of surgery.Methods: this is a prospective study, in which two hundred thirty childhood tonsillectomies were performed as a day-case in the department of otolaryngology at Al Shaheed Gazi hospital, Medical City Complex during the period from October 2009 to September 2010. The patients age range from 3-12 years (Mean 7.2 years).Results: 46.08% males and 53.91% females wer
... Show MoreThe research tagged (Digital Collage in Contemporary Art) consisted of four chapters. The first chapter was devoted to the methodological framework of the research. The problem ended with the following questions: How does digital collage represent contemporary art? What is the variable at the level of meaning shifts in composing works according to the digital collage? Was the digital collage a qualitative leap in the path of the aesthetic pattern in art? How does digital collage interfere with contemporary life and societies? It included the aim of the research and its importance, while the second chapter dealt with two topics, the first (reading in the concept of collage), and the second (digital collage). The third chapter was devoted
... Show MoreDomestic Technique in Batik Art
This research deals with dialogic submission as one of the most important deliberative topics in the process of linguistic communication between the two sides of the discourse, and therefore we find in this research its concept among the ancient Arabs of grammarians, rhetoric and fundamentalists, and we started with Western linguists as a result of their knowledge of the philosophy of language, and this research was satisfied with the principle of cooperation that came By Grace as the founder of this modern deliberative topic with an attempt to monitor this principle in the prophetic stories and the susceptibility of the stories to this kind of implicit communication, as the prophetic stories included multiple deliberative dimensions of
... Show MoreImplantable drug delivery systems, such as drug pumps and polymeric drug depots, have emerged as means of providing predetermined drug release profiles at the desired site of action. While initial implants aimed at providing an enduring drug supply, developments in polymer chemistry and pharmaceutical technology and the growing need for refined drug delivery patterns have prompted the design of sophisticated drug delivery implants such as on-demand drug-eluting implants and personalized 3D printed implants. The types of cargo loaded into these implants range from small drug molecules to hormones and even therapeutic cells. This review will shed light upon recent advances in materials and composites used for polymeric implant fabrication, hi
... Show MoreThat water is the lifeblood and without it no life on our planet, he says in the Holy Koran: In the Name of God {{And We made from water every living thing}} truth of God Almighty (the prophets verse 30) The basis of the existence of settlements served human and a source of fresh water close to it easy access to it is used for domestic, agricultural, on a daily basis, even closer look at the map of Iraq to human settlement to find it is a signatory to both sides of the river are thick and less as we moved away from the source of water until they make up a scene like a necklace the river and the stones of cities and settlements served, was the ancient civilizations, countries and capitals Throughout history, choose sites near sour
... Show MoreThe development of better tools for diagnosis and more accurate prognosis of cancer includes the search for biomarkers; molecules whose presence, absence or change in quantity or structure is associated with a particular tumour or prognosis/therapeutic outcome. While biomarkers need not be functionally relevant, if cell survival, then they could also provide new targets for therapeutic drugs. In recent years attention has been applied to a group of proteins known as cancer testis antigens (CT antigens) [1]. These proteins are products of genes whose expression was normally confined to the testis, yet they are expressed in tumour cells. CT genes are bound to serve a wide array of roles in the testes, which have many highly differentiated cel
... Show MoreThe difference and pluralism among members of the same society is a fact undeniable and ignored, passed by the Quran, and confirmed by the Sunnah of the Prophet Mohammed in more than one occasion, so that the Apostle r placed a document included in its terms an agreement with the Jews, and recognized the coexistence between Muslims and Jews, which stems from the great principle of a tolerance, which recognizes the rights of others and the freedom to believe what is believed to be right, so it was incumbent upon us, and we live in rivalry repulsion and jealousies to recognize the principle of coexistence with the other, and accept it in accordance with the legitimate controls with pride of belonging to the Islamic religion, in this sense
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