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 invisibility as a Poisson thinning process and show that invisibility is even more pronounced with channel abundance. Following the disk graph model, we define and characterize connectivity of the secondary network in terms of the available number of channels, deployment densities, number of transceivers per node, and communication range. When primary users are absent, we derive the critical number of channels which maintains super-criticality of the secondary network. When primary users are present, we characterize and analyze the connectivity for all the regions: channel abundance, optimal, and channel deprivation. Our results can be used to decide on the goodness of any channel rendezvous algorithm by computing the expected resultant connectivity.
The study aimed to identify the psychological counseling skills and the strength of the ego in the educational counselors, and to identify the relationship of statistical significance between the psychological counseling skills and the strength of the ego in the educational counselors, and to identify the differences of statistical significance in the relationship between psychological counseling skills and the strength of the ego in the guides according to the gender variable(male, Females), the number of sample (100) guides, including (50) males and (50) females from the area of Atifiya and Qadissiya and Ameriya in the Directorate of Education Karkh / 1, the researcher adopted a scale of psychological counseling skills prepared b
... Show MoreFemale infection with HPV (human papilla virus) has been established as an essential cause of CIN (cervical intraepithelial neoplasia). The danger of transformation from CIN to frank malignancy should be considered. Objective: The goal of this study is to evaluate the effectiveness of CO2 laser vaporization of ectocervical lesion high grade squamous intraepithelial lesion (HGSIL). Patients and Methods: Four Female out of 150 affected with HGSIL lesions were submitted to CO2 laser vaporization and followed up in 4 months later, and 10 women with HGSIL lesion submitted to electrocautery diathermy for the comparison. Results: Among women treated by CO2 laser vaporization, 3 women had negative results (clear cervix), at 4 months follow up; o
... Show MoreBig data usually running in large-scale and centralized key management systems. However, the centralized key management systems are increasing the problems such as single point of failure, exchanging a secret key over insecure channels, third-party query, and key escrow problem. To avoid these problems, we propose an improved certificate-based encryption scheme that ensures data confidentiality by combining symmetric and asymmetric cryptography schemes. The combination can be implemented by using the Advanced Encryption Standard (AES) and Elliptic Curve Diffie-Hellman (ECDH). The proposed scheme is an enhanced version of the Certificate-Based Encryption (CBE) scheme and preserves all its advantages. However
... Show MoreMorphological and histoarchitecture aspects on the cerebrum of (barn owl) were made
to find outthe cerebrum size, design and the description of cerebral region components at the
light microscopic level by using Haematoxylin – Eosin and periodic acid schift (PAS)
stain methods. The result of the morphological aspects revealed that the cerebrum was large
and an obtuse triangle in shape, its surface had a slight furrow. Sagittal sections revealed
the location, arrangement and size of pallial and subpallial cerebral divisions. The result of
the microscopic examinations indicated that the large and massive hyperpallium (wulst) was
thick,hypertrophied wired, and multilaminate structure reflect their wider ste
La condicionalidad en árabe, supongo como en otras lenguas, constituye una noción amplia que puede expresarse mediante diferentes construcciones sintácticas. La mayor parte de los especialistas coinciden en señalar que las estructuras condicionales son, probablemente, la clase más compleja de expresión compuesta en árabe. Se utilizan para expresar una condición de la que depende la realización de lo expuesto en la oración principal. Las estructuras condicionales son una de las principales vías lingüísticas de las que dispone el individuo para expresar su capacidad de imaginar situaciones diferentes a las reales; de crear mundos posibles; de soñar con situaciones pasadas que podrían haber sido diferentes; de ocultar lo fact
... Show MoreThe current research contains four chapters. The first topic included the methodological framework that included the problem of research and the need for it, and then the importance of the research, and then the aim of the research, its limits and the definition of terms linguistically, conventionally and procedurally. The second chapter (the theoretical framework) contained two topics, the topic The first is titled: The Outward Vision in Child Theater Performances, while the second topic was titled: Presentation Technology in Child Theater, Chapter Four (Research Procedures), which organized the research community and analyzed its sample, and the fourth chapter contained research results, conclusions and recommendations. The prop
... Show Morerepresent websites link support of human communicate and cohesion of cultures different depending on their languages and their environments around, it was the evolution of one of the most important means of communication of services for electronic networks, the Internet active role in containing the world Bbodqh science and knowledge to Taatlaqah cultures from which derives its intellectual and cognitive cupboards continuity and as a link language for each those environmental Altdadat, linguistic, religious, political, economic . We all know that these electronic means difficult promise ring intellectual and mental connectivity for the masses polarized without being of the image as an element Kravekaa supporter of the electronic media an
... Show MorePurpose – measure the relationship between operation management strategies as an independent variable on the customer's delight as an approved variable.
Design/methodology/approach – The research sample vocabulary included sales representatives and customers of the researched markets at a rate of (100%). The recovery rate is (95) Customers and (95) delegates for the products for the factory in neighbourhood (Banooks and Karrada ) regions were randomly chosen from an open community in these two residential areas. Statistical methods were used (arithmetic media, standard deviations, t-test, correlation coefficient (Horst), simple regression analysis).
Findings – The people in charge of the factory management nee
... Show MoreObjectives: This study aims to determine the disease’s patterns and outcomes of admission among neonates hospitalized at the neonatal care unit in Erbil City, and using the findings as a baseline for neonate’s morbidity and mortality assessment in the future. Methodology: A retrospective study carried out at neonatal care unit of Raparin pediatric teaching hospital. An instrument for data collection developed by researcher included (age, gender, cause of admission, diagnosis and outcome upon discharge and causes of death). Content validity of the instrument was determined through the use of panel ex
Zooplanktons from the artificial lake of Madenat Al-Alaab at Baghdad city have been
studied, during the period from may 2009 to April 2010. In addition to some ecological
factors (Temperature, pH and Turbidity) which were ranged (10.2-28.4)°C (7.1-8.4) and (20-50) cm respectively.
The results of the present study revealed that there are 22 species of zooplankton
belonging to Cladocera, Copepoda and Rotifera. Some of the species recorded during all
months of the study period, while other have disappeared during some months. Numbers of
species recorded were varied during different groups .
The dominant species were (Cyclops vernalis, C. hyalinus, C. scutifer, Diaptomus
leptopus, Bosmina longirostris, Kerate