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Search Results: 1 - 10 of 505 matches for " Shahram "
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Cognitive Congestion Control for Data Portals with Variable Link Capacity  [PDF]
Ershad Sharifahmadian, Shahram Latifi
Int'l J. of Communications, Network and System Sciences (IJCNS) , 2012, DOI: 10.4236/ijcns.2012.58058
Abstract: Network congestion, one of the challenging tasks in communication networks, leads to queuing delays, packet loss, or the blocking of new connections. In this study, a data portal is considered as an application-based network, and a cognitive method is proposed to deal with congestion in this kind of network. Unlike previous methods for congestion control, the proposed method is an effective approach for congestion control when the link capacity and information inquiries are unknown or variable. Using sufficient training samples and the current value of the network parameters, available bandwidth is adjusted to distribute the bandwidth among the active flows. The proposed cognitive method was tested under such situations as unexpected variations in link capacity and oscillatory behavior of the bandwidth. Based on simulation results, the proposed method is capable of adjusting the available bandwidth by tuning the queue length, and provides a stable queue in the network.
Decentralization of a Multi Data Source Distributed Processing System Using a Distributed Hash Table  [PDF]
Grzegorz Chmaj, Shahram Latifi
Int'l J. of Communications, Network and System Sciences (IJCNS) , 2013, DOI: 10.4236/ijcns.2013.610047
Abstract: A distributed processing system (DPS) contains many autonomous nodes, which contribute their own computing power. DPS is considered a unified logical structure, operating in a distributed manner; the processing tasks are divided into fragments and assigned to various nodes for processing. That type of operation requires and involves a great deal of communication. We propose to use the decentralized approach, based on a distributed hash table, to reduce the communication overhead and remove the server unit, thus avoiding having a single point of failure in the system. This paper proposes a mathematical model and algorithms that are implemented in a dedicated experimental system. Using the decentralized approach, this study demonstrates the efficient operation of a decentralized system which results in a reduced energy emission.
On Point-Based Haptic Rendering  [PDF]
Shi Wen, Shahram Payandeh
Engineering (ENG) , 2013, DOI: 10.4236/eng.2013.55A003
Abstract: Haptic rendering is referred to as an approach for complementing graphical model of the virtual object with mechanics- based properties. As a result, when the user interacts with the virtual object through a haptic device, the object can graphically deflect or deform following laws of mechanics. In addition, the user is able to feel the resulting interaction force when interacting with the virtual object. This paper presents a study of defining the levels-of-detail (LOD) in point-based computational mechanics for haptic rendering of objects. The approach uses the description of object as a set of sampled points. In comparison with the finite element method (FEM), point-based approach does not rely on any predefined mesh representation and depends on the point representation of the volume of the object. Different from solving the governing equations of motion representing the entire object based on pre-defined mesh representation which is used in FEM, in point-based modeling approach, the number of points involved in the computation of displacement/deformation can be adaptively defined during the solution cycle. This frame work can offer the implementation of the notion for levels-of-detail techniques for which can be used to tune the haptic rendering environment for in- creased realism and computational efficiency. This paper presents some initial experimental studies in implementing LOD in such environment.

Preana: Game Theory Based Prediction with Reinforcement Learning  [PDF]
Zahra Eftekhari, Shahram Rahimi
Natural Science (NS) , 2014, DOI: 10.4236/ns.2014.613099
Abstract:

In this article, we have developed a game theory based prediction tool, named Preana, based on a promising model developed by Professor Bruce Beuno de Mesquita. The first part of this work is dedicated to exploration of the specifics of Mesquita’s algorithm and reproduction of the factors and features that have not been revealed in literature. In addition, we have developed a learning mechanism to model the players’ reasoning ability when it comes to taking risks. Preana can predict the outcome of any issue with multiple steak-holders who have conflicting interests in economic, business, and political sciences. We have utilized game theory, expected utility theory, Median voter theory, probability distribution and reinforcement learning. We were able to reproduce Mesquita’s reported results and have included two case studies from his publications and compared his results to that of Preana. We have also applied Preana on Irans 2013 presidential election to verify the accuracy of the prediction made by Preana.

A counterexample to the article “On the fixed points of affine nonexpansive mappings”
Shahram Saeidi
International Journal of Mathematics and Mathematical Sciences , 2006, DOI: 10.1155/ijmms/2006/89475
Abstract: We give a counterexample to the article “On the fixed points of affine nonexpansive mappings” (2001).
Effects of epidural lidocaine analgesia on labor and delivery: A randomized, prospective, controlled trial
Shahram Nafisi
BMC Anesthesiology , 2006, DOI: 10.1186/1471-2253-6-15
Abstract: 395 healthy, nulliparous women, at term, presented in spontaneous labor with a singleton vertex presentation. These patients were randomized to receive analgesia either, epidural with bolus doses of 1% lidocaine or intravenous, with meperidine 25 to 50 mg when their cervix was dilated to 4 centimeters. The duration of the active-first and second stages of labor and the neonatal apgar scores were recorded, in each patient. The total number of vacuum-assisted and cesarean deliveries were also measured.197 women were randomized to the epidural group. 198 women were randomized to the single-dose intravenous meperidine group. There was no statistical difference in rates of vacuum-assisted delivery rate. Cesarean deliveries, as a consequence of fetal bradycardia or dystocia, did not differ significantly between the groups. Differences in the duration of the active-first and the second stages of labor were not statistically significant. The number of newborns with 1-min and 5-min Apgar scores less than 7, did not differ significantly between both analgesia groups.Epidural analgesia with 1% lidocaine does not prolong the active-first and second stages of labor and does not increase vacuum-assisted or cesarean delivery rate.Labor pain is a common phenomenon that can be mitigated by pharmacological and non-pharmacological methods. Epidural techniques can be used to provide complete analgesia during labor [1,2], but some authors believe that epidural analgesia prolongs labor [2-4], and can increase the need for instrumental [1,3,4], or cesarean delivery [5-8].We performed a controlled trial of 395 nulliparous women who were randomized to either epidural analgesia or single dose intravenous meperidine for pain relief during labor. Our primary purpose was to determine whether the use of 1% lidocaine for epidural analgesia during labor affects duration of second labor stage. Our secondary purposes were the rate of cesarean delivery and neonatal apgar score, vacuum-assisted delive
Land Suitability Analysis for Wheat Using Multicriteria Evalution and GIS Method
Shahram Ashraf
Research Journal of Biological Sciences , 2012, DOI: 10.3923/rjbsci.2010.601.605
Abstract: The aim in integrating multi-criteria evaluation with Geographical Information Systems (GIS) is to provide more flexible and more accurate decisions to the decision makers in order to valuate the effective factors. A GIS has been used to match the suitability for wheat crop based on the requirements of the crop and the quality and characteristics of land. The methodology used for the physical land suitability analysis for wheat is a multi-criteria evaluation approach within GIS context. This study, land suitability evaluation based on FAO has been determined for wheat irrigated area about 5400 ha, the South of plains Damghan. The study was carried out by overlapping all individual maps (soil map units, soil depth map, slope map, texture soil map and soil fertility) with GIS techniques for physical land suitability classification. The results show that 21.94% of the area is moderately suitable (S3) and 9.40 not suitable (N1) and 68.66% severe limitations and unchangeable (N2) for wheat crop. Lack of irrigation suitable water, Exchange Sodium Percent (ESP) and salinity (EC), insufficient rainfall and poor soil fertility are the most serious problems influencing yield and quality of wheat.
"[99mTc-DMSA (V)] in Detection of Metastases of Medullary Thyroid Carcinoma "
Shahram Dabiri
Iranian Journal of Nuclear Medicine , 2006,
Abstract: Introduction: Medullary thyroid carcinoma (MTC) is a rare thyroid cancer secreting calcitonin (CT) which is the most sensitive and specific tumor marker for MTC. This type of thyroid cancer is able to metastasize to different body areas including regional lymph nodes, lungs, liver and bone. The aim of this study was to assess the sensitivity and specificity of [99mTc-DMSA (V)] whole body scan (WBS) in detection of metastases in MTC. Methods: This descriptive and prospective study was performed in 15 patients with MTC referred to our nuclear medicine centre since 2004 to 2005. These patients were compared regarding age, sex, and duration of the disease. Sensitivity and specificity of each diagnostic modality in detection of metastases were calculated and compared statistically. Results: [99mTc-DMSA (V)] showed 91% sensitivity and 75% specificity as compared with serum calcitonin as gold standard. The figures for CT scan were 82% and 45%, respectively. CEA showed 64% sensitivity and 50% specificity. Conclusion: It is concluded that despite the slightly lower sensitivity and specificity of [99mTc-DMSA (V)] as compared to calcitonin (Gold-standard method), this radiotracer can be used for identification of recurrence or metastasis of medullary thyroid carcinoma.
An empirical method to measure the relative efficiency of dairy producers using deterministic frontier analysis
Shahram RostamPour
Management Science Letters , 2012,
Abstract: The purpose of this paper is to measure the relative efficiencies of various cow husbandries. The proposed model of this paper uses distribution free analysis to measure the performance of different units responsible for taking care of cows. We gather the necessary information of all units including number of cows, amount of internet usage, number of subunits for taking care of cows, amount of forage produced in each province for grazing livestock and average hour per person training courses as independent variables and consider the amount of produced milk as dependent variable. The necessary information are collected from all available units located in different provinces of Iran and the production function is estimated using a linear programming model. The results indicate that the capital city of Iran, Tehran, holds the highest technical efficiency, the lowest efficiency belongs to province of Ilam and other provinces mostly performs poorly.
Ranking provinces based on development scale in agriculture sector using taxonomy technique
Shahram Rostampour
Management Science Letters , 2012,
Abstract: The purpose of this paper is to determine comparative ranking of agricultural development in different provinces of Iran using taxonomy technique. The independent variables are amount of annual rainfall amount, the number of permanent rivers, the width of pastures and forest, cultivated level of agricultural harvests and garden harvests, number of beehives, the number of fish farming ranches, the number of tractors and combines, the number of cooperative production societies, the number of industrial cattle breeding and aviculture. The results indicate that the maximum development coefficient value is associated with Razavi Khorasan province followed by Mazandaran, East Azarbayjan while the minimum ranking value belongs to Bushehr province.
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