1,340 research outputs found
Adaptive Video Streaming Over Cognitive Radio Networks
No full textA Master of Science thesis in Electrical Engineering by Ala Eldin Omer Mohamed entitled, "Adaptive Video Streaming over Cognitive Radio Networks," submitted in January 2017. Thesis advisors are Dr. Mohamed Hassan and Dr. Mohamed El-Tarhuni. Soft and hard copy available.Several challenges face reliable video streaming over wireless networks due to the stringent requirements of high data rate, low error rate, and limited end-to-end delay. Cognitive radio (CR) networks offer a great advantage to unlicensed users (typically called secondary users) by allowing them to exploit the unused spectrum of licensed users (known as primary users) on an opportunistic basis. However, it is more challenging to deliver video services over dynamic CR channels that are available to secondary users not only intermittently but with all the challenges of wireless channels. In this research, several frameworks are proposed to stream different scalable videos from a base station to multiple secondary users over a CR network. The objective of this study is to ensure that end users will enjoy continuous video playback with acceptable perceptual quality. To achieve such a goal, a channel allocation algorithm is introduced to adaptively assign the available radio channels to secondary users while taking into considerations the quality of their assigned channels as well as their buffer occupancies. In addition, different streaming algorithms are devised to ensure the delivery of scalable video frames, with base and enhancement layers, within the delay constraints with priority given to the base-layer frames to guarantee the continuity of video playback. Moreover, adaptive modulation is used based on the importance of transmitted video information and the channel state information (CSI) as fed-back by secondary users. Extensive simulations are performed using SimEvents simulator in MATLAB, the results of which show that the proposed schemes that integrate the devised channel allocation and streaming algorithms with adaptive modulation and scalable source coding techniques react to the variations in the channel conditions and the dynamics of the secondary users’ playback buffers in an acceptable fashion. This in turn resulted in efficient usage of the available CR resources as demonstrated in the achieved peak signal-to-noise ratio (PSNR) of the reconstructed video streams with no interruptions in the playback process. It has also been shown that scalable videos outperform their single-layer counterparts in terms of the achieved video quality. Finally, it is shown that joint adaptive modulation and channel coding results in improved bandwidth utilization, continuous playback and enhanced perceptual video quality at the secondary users end.College of EngineeringDepartment of Electrical EngineeringMaster of Science in Electrical Engineering (MSEE
Supplemental Material - Aspirin Use as a Risk Factor for Marginal Ulceration in Roux-en-Y Gastric Bypass Patients: A Meta-Analysis of 24,770 Patients
No full textSupplemental Material for Aspirin Use as a Risk Factor for Marginal Ulceration in Roux-en-Y Gastric Bypass Patients: A Meta-Analysis of 24,770 Patients by Ray C. Portela, Ishna Sharma, Ahmet Vahibe, Omer Hassan, Konstantinos Spaniolas, Barham Abu Dayyeh, Benjamin Clapp, and Omar M. Ghanem in The American Surgeon</p
Complex permittivity of materials at broadband frequency using transmission phase shift method
No full textThis paper reports determination of complex relative permittivity of non-magnetic samples Teflon, Nylon and Epoxy via transmission phase shift method. The transmission phase shift method offers calibration independent and invariant position features. In this work, a Coaxial Cavity Test Fixture (CCTF) with dimension of 1.8 and 4.1 mm for inner and outer conductor, respectively was customized based on impedance matching theory to study broadband scattering in the range of frequency 1-18 GHz. Impedance matching and cable calibration were performed to reduce the measurement error of scattering parameters; reflection and transmission . Magnitude and phase of and were measured by vector network analyzer (VNA). The measured phase of ( ) for all samples under test were linearized using the MATLAB “unwrap” command for further calculation of . The phase shift in between with and without sample inside the cavity was detected and it was used to determine for each material under test. The average value of dielectric constants for Teflon, Nylon and Epoxy were 2.11, 2.42 and 3.05, correspondingly for the selected frequency 2, 4, 6, 8, 10, 12 and 14 GHz. While, the average of dielectric losses for Teflon and Epoxy were almost overlapped which the values were 0.001 and 0.002, respectively that were higher than that of Nylon at 0.0006. The calculated values are comparable with the theoretical values with small absolute errors. These results suggested that this transmission phase shift method using CCTF was equally consistent when compared to the other techniques used for the determination of and
Hassan Sheikh Muumin: The Hoobal as Creator, Preserver, and Social Critic of the National Heritage
No full textThis article introduces us the figure of Hassan Sheikh Muumin, one of Somalia's greatet modern songwriters and playwrights. After an introduction about the life and the career of the poet, four of Hassan's songs, two dealing with women, and two with politics are presented in their English version.Maqaalkaani wuxuu ka hadlayaa Xasan Sheekh Muumin, oo ah mid ka mid ah abwaaniinta waaweyn ee soomaaliyeed. Taariikh noololeedkiisa ee guud kasokow, waxaa halkaan laga helayaa afar hees uu tiriyay abwaanku, labo haweenka ayay ku saabsanyihiin, labada kalena siyaasadda, af ingiriisi ayayna ku tarjumanyihiin.Questo articolo ci presenta la figura di Hassan Sheikh Muumin, uno dei più grandi compositori e poeti moderni della Somalia. Dopo un'introduzione sulla vita e sulla carriera del poeta, sono presentate quattro canzoni di Hassan, due relative alle donne e due alla politica, nella loro versione inglese.Document provided by Bildhaan, Digital Commons at Macalester College.Dokumentigan waxaa dadka u soo bandhigay Bildhaan, Digital Commons ee jaamacadda "Macalester College"Documento messo a disposizione da Bildhaan, Digital Commons del Macalester College.Link: http://digitalcommons.macalester.edu/bildhaan
Management of Hospitals Wastewater
No full textHospital wastewater management is an integral part of human welfare .The improper
wastewater management reduces the over all benefits of health care, increase the
environmental risks, and decrease the productivity.
Wastewater from hospitals and laboratories is of a similar quality to urban
wastewater, but it may contain various potentially hazardous components. The most
recognized metalic pollutants of concern are nickel, copper, zinc, silver and mercury.
On the other hand, non-metallic pollutants of concern include cyanide, phenolic
compounds such as picric acid, formaldehyde and other solvents.
There are 93 hospitals in Khartoum State with 6801 beds. Every day nearly 2585
cubic meters of wastewater is discharged from these hospitals to the subsurface water,
Nile River, and the municipal net without pretreatment or awareness regard the
hazardous characteristics of this waste. Annually more than 68 kg of pure silver is
discharged from x-ray units to the hospitals sewers without recovering.
As a result of these practices water sources and soil may be polluted and thus,
community is exposed to infectious and toxic effects.
In this study laboratory tests were performed to estimate the characteristics of hospital
waste streams and to specify the most occurring hazardous elements. This study made
an approach to perform a Hospital Pollution Prevention Checklist and developed a
designing program for septic tank units
Jérusalem dans l'oeuvre des graveurs israéliens = Jerusalem and the Israeli Printmaker
No full textTracing a history of the Holy City's representation from the sacred texts through Israeli art of the time (1979), Omer briefly presents 18 printmakers through their respective itineraries and styles, stressing their influence on the development and practice of the medium. The author elaborates on Jerusalem's academic institutions, its museums and their collections. Artists alphabetically indexed, with biographical notes and reproductions. Texts in English, French and Hebrew
Introduction::How and why should we study dialogue?
No full textThis chapter (pp. 17-28) introduces the volume edited by Omer Sener, Frances Sleap, and Paul Weller (2016), Dialogue Theories II, The Dialogue Society, London. [ISBN 978-0-9934258-0-6]. In doing so it puts the book in a wider context of the previous volume on Dialogue Theories published (2013) by the Dialogue Society, as well as of the Journal of Dialogue Studies of which the author is academic editor. It discusses a range of key questions and "working definitions" about the nature of dialogue and critically evaluates a range of differing articulations of the aims and objectives of dialogue itself, and in relation to the study of it
Epidemiological Aspects of Human and animal brucellosis in Sudan
No full textBrucellosis is one of the most important zoonatic diseases responsible
for high economic losses and high morbidity in endemic areas . in the Sudan
the disease occurs in all animal species including wild life and humans. This
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study was conducted by collecting data from records of the Federal Ministry
of Health. the data included annual cases of human brucellosis from 2006-
2010 in different states of the Sudan (Notheren- Red Sea- EL Gezira- EL
Gadarief- White Nile- Blue Nile- South Darfur- North Darfur- West Darfur-
South Kordufan- North kordufan- River Nile- Kassala- Sinnar). The data
included ages of patients and their distribution according to sex and
prevalence of brucellosis was calculated for each state. EL Gezira state
showed the highest prevalence rate due to the large numbers of livestock and
the close associating of their owners with them without precaution measure
and their wrong habits like drinking raw milk .El Gadarief state followed El
Gazira in the high prevalence of brucellosis because of con of livestock in El
Butana area north of the state during the raining season. The age groups
from 25-44 years showed the highest infection rate being the working group
in farms and grazing and hence most exposed to the source of
infection(animals)
Analysis of the University of Khartoum Library System Using the Structured Systems Analysis and Design Methodology (SSADM)
No full textهدفت هذه الورقة الى دراسة و تحليل نظام مكتبة جامعة الخرطوم من حيث العمليات والوظائف التى تجرى في اقسام المكتبة الاساسية وهى قسم التزويد، قسم الفهرسة والتصنيف، وقسم خدمات المستفيدين. الغرض من هذا التحليل هو استخدامه لاحقا في تحديد المتطلبات الوظيفية الخاصة بنظام إدارة مكتبات مبنى على الحاسوب. تم استخدام عددا من الطرق لجمع البيانات عن نظام المكتبة القائم تشتمل على المقابلات، تحليل الوثائق، ومراجعة الادبيات في مجال تحليل وتصميم النظم. وتم استخدام منهجية تحليل وتصميم النظم الهيكلية
Systems Analysis and Design Methodology (SSA) Structured
والتى تتطلب تفكيك النظام القائم الى نظم فرعية اصغر. واخيرا تم توثيق عملية تحليل النظام القائم باستخدام مخططات تدفق البيانات .Data Flow Diagrams (DFD) This paper investigated and analyzed the University of Khartoum Library System in terms of the operations and functions carried out in the three core sections of the library i.e. the Acquisitions, the Cataloguing and classification, and the Reader Services (Circulation) Sections. The purpose of the study was that the analysis would be used later as the basis for determining the specific functional requirements of a computer-based Integrated Library Management System (ILMS). The author employed a number of techniques for the purpose of gathering information about the existing library system, including interviews, document analysis, and literature review. The study used the Structured Systems Analysis Methodology (SSA) in analyzing the existing library system. This method necessitated the decomposition of the system into smaller functional subsystems. The study finally documented the results of the University of Khartoum Library System analysis by Data Flow Diagrams (DFDs). 
The origin of the red emission in n-ZnO nanotubes/p-GaN white light emitting diodes
No full textIn this article, the electroluminescence (EL) spectra of zinc oxide (ZnO) nanotubes/p-GaN light emitting diodes (LEDs) annealed in different ambients (argon, air, oxygen, and nitrogen) have been investigated. The ZnO nanotubes by aqueous chemical growth (ACG) technique on p-GaN substrates were obtained. The as-grown ZnO nanotubes were annealed in different ambients at 600 degrees C for 30 min. The EL investigations showed that air, oxygen, and nitrogen annealing ambients have strongly affected the deep level emission bands in ZnO. It was concluded from the EL investigation that more than one deep level defect is involved in the red emission appearing between 620 and 750 nm and that the red emission in ZnO can be attributed to oxygen interstitials (O-i) appearing in the range from 620 nm (1.99 eV) to 690 nm (1.79 eV), and to oxygen vacancies (V-o) appearing in the range from 690 nm (1.79 eV) to 750 nm (1.65 eV). The annealing ambients, especially the nitrogen ambient, were also found to greatly influence the color-rendering properties and increase the CRI of the as - grown LEDs from 87 to 96.The original publication is available at www.springerlink.com:Naveed Ul Hassan Alvi, Kamran Ul Hasan, Omer Nur and Magnus Willander, The origin of the red emission in n-ZnO nanotubes/p-GaN white light emitting diodes, 2011, NANOSCALE RESEARCH LETTERS, (6), 1, 130.http://dx.doi.org/10.1186/1556-276X-6-130Licensee: Springer Science Business Mediahttp://www.springerlink.com
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