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Search Results: 1 - 10 of 505 matches for " Irfan Kuvvetli "
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Effects of Bulk and Surface Conductivity on the Performance of CdZnTe Pixel Detectors
Aleksey E. Bolotnikov,C. M. Hubert Chen,Walter R. Cook,Fiona A. Harrison,Irfan Kuvvetli,Stephen M. Schindler
Physics , 2001, DOI: 10.1109/TNS.2002.801673
Abstract: We studied the effects of bulk and surface conductivity on the performance of high-resistivity CdZnTe (CZT) pixel detectors with Pt contacts. We emphasize the difference in mechanisms of the bulk and surface conductivity as indicated by their different temperature behaviors. In addition, the existence of a thin (10-100 A) oxide layer on the surface of CZT, formed during the fabrication process, affects both bulk and surface leakage currents. We demonstrate that the measured I-V dependencies of bulk current can be explained by considering the CZT detector as a metal-semiconductor-metal system with two back-to-back Schottky-barrier contacts. The high surface leakage current is apparently due to the presence of a low-resistivity surface layer that has characteristics which differ considerably from those of the bulk material. This surface layer has a profound effect on the charge collection efficiency in detectors with multi-contact geometry; some fraction of the electric field lines originated on the cathode intersects the surface areas between the pixel contacts where the charge produced by an ionizing particle gets trapped. To overcome this effect we place a grid of thin electrodes between the pixel contacts; when the grid is negatively biased, the strong electric field in the gaps between the pixels forces the electrons landing on the surface to move toward the contacts, preventing the charge loss. We have investigated these effects by using CZT pixel detectors indium bump bonded to a custom-built VLSI readout chip.
Multiple Levels of Abstraction in the Simulation of Microthreaded Many-Core Architectures  [PDF]
Irfan Uddin
Open Journal of Modelling and Simulation (OJMSi) , 2015, DOI: 10.4236/ojmsi.2015.34017
Abstract: Simulators are generally used during the design of computer architectures. Typically, different simulators with different levels of complexity, speed and accuracy are used. However, for early design space exploration, simulators with less complexity, high simulation speed and reasonable accuracy are desired. It is also required that these simulators have a short development time and that changes in the design require less effort in the implementation in order to perform experiments and see the effects of changes in the design. These simulators are termed high-level simulators in the context of computer architecture. In this paper, we present multiple levels of abstractions in a high-level simulation of a general-purpose many-core system, where the objective of every level is to improve the accuracy in simulation without significantly affecting the complexity and simulation speed.
Fairness Aware Group Proportional Frequency Domain Resource Allocation in L-SC-FDMA Based Uplink  [PDF]
Irfan Ahmed, Amr Mohamed
Int'l J. of Communications, Network and System Sciences (IJCNS) , 2011, DOI: 10.4236/ijcns.2011.48060
Abstract: This paper presents virtual clusters based proportional fairness and resource allocation scheme for Localized Single Carrier Frequency Division Multiple Access (L-SC-FDMA). L-SC-FDMA has been selected as the uplink transmission scheme in 3GPP Long Term Evolution (LTE) due to its low Peak to Average Power Ratio (PAPR) over OFDMA in general and high rate-sum capacity over Interleaved SC-FDMA in particular. Virtual cluster-based proportional fairness (VCPF) scheduler exploits the link adaptation information available at MAC layer to form virtual clusters. The distributed proportional fairness scheduler ensures a minimum throughput for all users in the coverage area by assigning contiguous RBs, proportional to the throughput and the number of users in a particular cluster or group. Simulations have been performed using practical scenario of uniformly distributed users in Rayleigh faded coverage area and design formulas have been devised for network planning to get the best possible fairness with promising level of quality of service (QoS).
Uniformly Illuminated Efficient Daylighting System  [PDF]
Irfan Ullah, Seoyong Shin
Smart Grid and Renewable Energy (SGRE) , 2013, DOI: 10.4236/sgre.2013.42020

Different approaches have been introduced for the daylighting system to reduce energy consumption, but they were not populated due to complex, high cost, and insufficient designs. There has been a recent problem in achieving uniform distribution of sunlight at a destination deep inside the building. Therefore, we propose a system to achieve high illumination by illuminating the surface of the absorber (optical fibers) uniformly. To capture sunlight, parabolic reflector and Fresnel lens are used. Different reflectors and lenses are considered, compared, and investigated to direct uniform light, which solves the heat problem, into the optical fibers. In addition, this study includes comparison between fiber-based daylighting systems. The proposed system has been verified through simulation and experimental results.

Simulation Study of Heliostat-Based Daylighting System for Multi-Story Buildings  [PDF]
Irfan Ullah, Seoyong Shin
Journal of Power and Energy Engineering (JPEE) , 2015, DOI: 10.4236/jpee.2015.34054

The following article has been retracted due to the fact that it cannot be accepted as Duplicate Publication. The Editorial Board takes a very strong respect to the author’s situation on this matter. This paper published in Journal of Power and Energy Engineering Vol.3 No.4, April 2015, has been removed from this site.

Academic Diversity and Assessment Process for CS Program Accreditation  [PDF]
Arif Bhatti, Irfan Ahmed
Creative Education (CE) , 2015, DOI: 10.4236/ce.2015.68080
Abstract: Underdeveloped countries have realized that the investment and the improvement in higher education are very important for the progress. This is evident in the number of new universities and institutes of higher learning are established in the last 20 - 30 years. In these universities, administrative processes are well established but academic processes are not. Accreditation bodies such as ABET do not dictate any specific assessment process but want each candidate program to have an assessment process that is reliable and can find out weak points in the program to continuously improve. This paper describes a successful assessment process adopted at College of Computers and Information Technology, Taif University.
The Integrated Model Using Agile Practices to CBR  [PDF]
Fizza Khalid, Irfan Ahmed
Journal of Software Engineering and Applications (JSEA) , 2017, DOI: 10.4236/jsea.2017.105024
Abstract: Agile development methodology works as a bridge, creating a composite control that changes the way of software development tasks. In this study, we have introduced a framework, integrated with artificial intelligence (AI) techniques, agile software development and its practice. The skilled developer is useful for implementing the method according to the reaction of the evaluation framework. The idea of agile and CBR procedure used to improve the current model. This model provides a comprehensive guide to the use of Agile development practices to be integrated with CBR for software development. Agile development methods used by CBR and RBR provide a more efficient and accurate working scenario. Case based reasoning is just the domain limited number of cases, while rules based reasoning is the technique of the generic and specific rules of the issue. Experts give feedback about the framework and they are satisfied with the functioning of the framework. The framework and its results were evaluated by the domain experts and case studies.
Etiologic Factors, Risk Factors, Diagnoses, and Importance of Colonoscopy in Patients Hospitalized Due to Lower Gastrointestinal Bleeding From Emergency Services
Zikret K?seo?lu,Banu Kara,ümit Bildedo?an,Adnan Kuvvetli
Journal of Academic Emergency Medicine , 2012,
Abstract: Objective: It is estimated that 3 out of 7 people suffer lower gastrointestinal bleeding (LGIB) at some point in life, and it is a frequent cause of emergency department admission. In this study, we aimed to evaluate the etiological factors, risk factors, diagnoses and the importance of colonoscopy in patients with LGIB. Material and Methods: Forty-three cases with LGIB who were referred to the Emergency Department of Adana Numune Training and Research Hospital, between January 2010 and January 2011 and examined with colonoscopy in the Gastroenterology and General Surgery Departments were retrospectively investigated. Demographical characteristics, etiology, risk factors, diagnoses and treatment modalities were determined.Results: Twenty-five patients with LGIB (58.1%) were male and 18 (41.9%) were female. The patients were aged between 18 and 85 years. Mean age (±SD) was 56.4±22.4. The average age (36.1±15.7) of patients with hemorrhoids and anal fissures were lower than others (69.7±14.9) (p<0.001). Signs and symptoms of the patients on admission were; melena 13 (30.2%) cases, hematemesis 1 (2.3%) case, hematemesis-melena 1 (2.3%) case, hematochezia 25 (58.1%) cases, abdominal pain 13 (30.2%) cases, and other reasons 1 (2.3%) case. Also, 7 patients (16.2%) had tachycardia, 4 (9.3%) had fever and 5 (11.6%) had hypotension. In terms of the associated diseases, 13 (30.2%) had hypertension, 4 (9.3%) had diabetes-mellitus, 6 (14.0%) had coronary artery disease, 2 (4.7%) had stroke, 1 (2.3%) had heart valve disease, and 1 (2.3%) had CRF. The anamnesis of LGIB was positive in 15 (34.9%) cases while smoking was positive in 14 (32.6%) cases. Risk factors for the disease were, use of aspirin for 8 (18.6%) cases, NSAIDs for 5 (11.6%) cases, anticoagulant for 2 (4.7%) cases, steroid for 2 (4.7%) cases, aspirin+NSAIDs for 2 (4.7%) cases and NSAIDs+anticoagulant for 1 (2.4%) case. Colonoscopic diagnosis of the patients were hemorrhoids for 14 (32.6%) cases, diverticulosis for 8 (18.6%) cases, ulcerative colitis for 7 (16.3%) cases, colorectal carcinoma for 4 (9.3%) cases, angiodysplasia for 3 (6.9%) cases and anal fissure for 3 (6.9%) cases. Colonoscopy was nondiagnostic in only four (9.3%) patients. 13 (30.2%) patients were given red blood cell transfusion, 7 (16.2%) antibiotics, 5 (11.6%) patients were treated endoscopically and 4 (9.3%) patients received surgical treatment.Conclusion: Diverticulosis was the most common cause of LGIB in older patients while ano-rectal diseases in younger patients. Most bleeding stopped spontaneously, and the remainder were succes
Bi-Criteria Optimization Technique in Stochastic System Maintenance Allocation Problem  [PDF]
Irfan Ali, S. Suhaib Hasan
American Journal of Operations Research (AJOR) , 2013, DOI: 10.4236/ajor.2013.31002

In this paper, the problem of optimum allocation of repairable and replaceable components in a system is formulated as a Bi-objective stochastic non linear programming problem. The system maintenance time and cost are random variable and has gamma and normal distribution respectively. A Bi-criteria optimization technique, weighted Tchebycheff is used to obtain the optimum allocation for a system. A numerical example is also presented to illustrate the computational details.

Knowledge Driven Paper Recommendation Using Heterogeneous Network Embedding Method  [PDF]
Irfan Ahmed, Zubair Ahmed Kalhoro
Journal of Computer and Communications (JCC) , 2018, DOI: 10.4236/jcc.2018.612016
Abstract: We search a variety of things over the Internet in our daily lives, and numerous search engines are available to get us more relevant results. With the rapid technological advancement, the internet has become a major source of obtaining information. Further, the advent of the Web2.0 era has led to an increased interaction between the user and the website. It has become challenging to provide information to users as per their interests. Because of copyright restrictions, most of existing research studies are confronting the lack of availability of the content of candidates recommending articles. The content of such articles is not always available freely and hence leads to inadequate recommendation results. Moreover, various research studies base recommendation on user profiles. Therefore, their recommendation needs a significant number of registered users in the system. In recent years, research work proves that Knowledge graphs have yielded better in generating quality recommendation results and alleviating sparsity and cold start issues. Network embedding techniques try to learn high quality feature vectors automatically from network structures, enabling vector-based measurers of node relatedness. Keeping the strength of Network embedding techniques, the proposed citation-based recommendation approach makes use of heterogeneous network embedding in generating recommendation results. The novelty of this paper is in exploiting the performance of a network embedding approach i.e., matapath2vec to generate paper recommendations. Unlike existing approaches, the proposed method has the capability of learning low-dimensional latent representation of nodes (i.e., research papers) in a network. We apply metapath2vec on a knowledge network built by the ACL Anthology Network (all about NLP) and use the node relatedness to generate item (research article) recommendations.
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