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Search Results: 1 - 10 of 1650 matches for " Mostafa Darvishi "
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A Novel Thermochemical Method for Fabrication and Theoretical Explanation of High Luminescent Mn-Doped CdS Nanoparticles  [PDF]
Mostafa Darvishi, Alireza Nikfarjam
Journal of Materials Science and Chemical Engineering (MSCE) , 2018, DOI: 10.4236/msce.2018.63001
Abstract: In this paper, fabrication and characterization of bare and doped CdS nanoparticles as well as investigating the luminescence properties of these particles as an important II-VI semiconductor are presented. A novel Thermochemical method was used for synthesis of these quantum dots. Thiols were used as the capping agent to prevent further growth during fabrication process. The application of TGA as a capping agent instead of TG was studied as a novel idea in this paper and was used practically in the synthesis of semiconductor nanoparticles. Using this process resulted in particles with sizes between 3 - 7 nm. Several samples were synthesized and characterized under various Mn ions doping ratio from 1:10 to 1:180, different temperatures from 40℃ to 96℃ and different pH values from 6 to 10. Synthesis of CdS nanoparticles with high Mn ions concentration resulted in luminescence decrement, while luminescence of nanoparticles was increased by decreasing Mn/Cd doping ratio until Mn:Cd = 1:180. The best fabrication temperature was obtained at 96℃ and the highest luminescence was observed at the pH value of 9. A theoretical explanation for the behavior of fabricated high luminescent quantum dots is presented based on the principles of quantum mechanics.
Circuit Level Modeling of Extra Combinational Delays in SRAM FPGAs Due to Transient Ionizing Radiation
Mostafa Darvishi,Yves Audet,Yves Blaquière,Claude Thibeault
Physics , 2015,
Abstract: This paper presents a novel circuit level model that explains and confirms the extra combinational delays in a SRAM-FPGA (Virtex-5) due to radiation, which matches the experimental results by proton irradiation at TRIUMF.
A New Approach for Wireless Cellular Network Design  [PDF]
Hamed Saghaei, Hamideh Saghaei, Malihe Darvishi
Int'l J. of Communications, Network and System Sciences (IJCNS) , 2013, DOI: 10.4236/ijcns.2013.62010
Abstract:

Wise arrangement of antennas is critical in wireless cellular systems for both reductions of co-channel interference (CCI) and increase the quality of service (QoS). In this paper, a novel architecture for antenna arrangement in CDMA wireless cellular systems is presented. In this architecture that we called Microzone, every cell is divided into three (or more) zones and information transmission in downlink channel is done by an antenna which is placed at the outer region of the related zone. Also, the transmitting signal by the mobile station (MS) in uplink channel is received by all the antennas of the related cell. Analytical calculations of the received signal to noise ratio (SIR) and outage probability for both microzone and used architectures show that proposed architecture has better performance in compared with the used architecture. Also, simulation results confirm lower outage probability in uplink channel for microzone architecture.

Introduce a Novel PCA Method for Intuitionistic Fuzzy Sets Based on Cross Entropy  [PDF]
Sonia Darvishi, Adel Fatemi, Pouya Faroughi
Applied Mathematics (AM) , 2015, DOI: 10.4236/am.2015.66091
Abstract: In this paper, a new method for Principal Component Analysis in intuitionistic fuzzy situations has been proposed. This approach is based on cross entropy as an information index. This new method is a useful method for data reduction for situations in which data are not exact. The inexactness in the situations assumed here is due to fuzziness and missing data information, so that we have two functions (membership and non-membership). Thus, method proposed here is suitable for Atanasov’s Intuitionistic Fuzzy Sets (A-IFSs) in which we have an uncertainty due to a mixture of fuzziness and missing data information. For the demonstration of the application of the method, we have used an example and have presented a conclusion.
The Comparison of Thick and Thin Intermediate Wafer in Maxillary Le Fort I Osteotomies  [PDF]
Farnoush Mohammadi, Naghmeh Bahrami, Aref Darvishi
International Journal of Clinical Medicine (IJCM) , 2018, DOI: 10.4236/ijcm.2018.91003
Abstract: Background: Osteotomy wafers were routinely used in orthognathic surgery for repositioning the mobilized maxilla to achieve the planned final occlusion. Objectives: The aim of the current study was to determine comparison of thick and thin intermediate wafer in maxillary Le Fort I osteotomies. Methods: This study was done in 9 patients who had maxillary prognathism or retrognathism abnormality. The maxillary cast was oriented using articulator after facebow transfer. Then photographic and cephalometric data was used to determine proper dental arch segments. All 9 patients had Le Fort I combined with mandibular sagittal split osteotomies. The Le Fort I surgery was done on lateral, septum and medial sinus of nasal and trigomaxillary. The cast was removed from the base articulator and think and thick wafers were fabricated for each. Then the wafers were fixed in 1, 2 and 3 mm anterior (A1, A2 and A3, respectively). After mobilization of the maxilla and adequate bone removal, the jaws were held in occlusion with the thin intermediate wafer. The maxilla was then located against the stable part of the facial skeleton above using the yet unoperated mandible as an autorotated guide. Then the superior reposition >1 or <1 m between two wafers was determined. Results: According to the results, the superior reposition was higher in thin wafers fixed in A3 > A2 compared to A1. Also, the same result was detected in thick wafers fixed in A3 > A2 compared to A1, respectively. However, there was no significant difference in both thin and thick wafers in each fixed locations. Conclusion: These results suggest thick wafers have acceptable results in maxillary Le Fort I osteotomies.
Synchrophasor monitoring of single line outages via area angle and susceptance
Atena Darvishi,Ian Dobson
Computer Science , 2013,
Abstract: The area angle is a scalar measure of power system area stress that responds to line outages within the area and is a combination of synchrophasor measurements of voltage angles around the border of the area. Both idealized and practical examples are given to show that the variation of the area angle for single line outages can be approximately related to changes in the overall susceptance of the area and the line outage severity.
Threshold-based monitoring of cascading outages with PMU measurements of area angle
Atena Darvishi,Ian Dobson
Computer Science , 2014,
Abstract: When power grids are heavily stressed with a bulk power transfer, it is useful to have a fast indication of the increased stress when multiple line outages occur. Reducing the bulk power transfer when the outages are severe could forestall further cascading of the outages. We show that synchrophasor measurements of voltage angles at all the area tie lines can be used to indicate the severity of multiple outages. These synchrophasor measurements are readily combined into an "area angle" that can quickly track the severity of multiple outages after they occur. We present a procedure to define thresholds for the area angle that relate to the maximum power that can be transferred through the area until a line limit is reached. Then in real time we would monitor the area angle and compare it to the thresholds when line outages occur to determine the urgency (or not) of actions to reduce the bulk transfer of power through the area. The procedure also identifies exceptional cases in which separate actions to resolve local power distribution problems are needed. We illustrate the thresholds and monitoring with the area angle across several states of Northwestern USA.
Use of an Energy-Like Integral to Study the Motion of an Axi-Symmetric Satellite under Drag and Radiation Pressure  [PDF]
Ahmed Mostafa
International Journal of Astronomy and Astrophysics (IJAA) , 2015, DOI: 10.4236/ijaa.2015.53019
Abstract: The axi-symmetric satellite problem including radiation pressure and drag is treated. The equations of motion of the satellite are derived. An energy-like is given for a general drag force function of the polar angle θ, and then it is used to find a relation for the orbit equation of the satellite with initial conditions satisfying the vanishing of arbitrarily choosing higher derivatives of the velocity.
The Predictive Value of Biopsy of the Pancreas and Its Therapeutic Impact in Autoimmune Diabetes  [PDF]
Wael Nassar, Mostafa A. Mostafa
Journal of Diabetes Mellitus (JDM) , 2014, DOI: 10.4236/jdm.2014.44041
Abstract: Diabetes Mellitus is by definition an end-stage organ failure. Type 1 diabetes mellitus (T1DM) is an autoimmune disease. Auto-inflammatory infiltrate appears to characterize the insulitis associated with T2DM. Recently, in 2013, Eva Corpos and colleagues described a comprehensive composition of peri-islet capsules and their basement membrane (BM). Virtanen I, Otonkoski T and Irving-Rodgers H.F. have reported similar descriptions few years earlier which have not been taken seriously as they deserve. Bluestone JA, Virtanen I and Irving-Rodgers H.F. and other colleagues reported that accumulation of the lymphocytes around the islets without invasion of the BM is the first step in disease induction (non-destructive insulitis phase). Invasion of the BM byleucocytic infiltration (destructive insulitis phase) occurs over a period of several years offering a good window for therapeutic intervention. Clinical symptoms appear only when 70% - 90% of β-cell mass are destroyed. This data emphasize the importance of identification and classification of such pathologic features by performing a biopsy of the pancreas with histoimmunochemistry analysis at the pre-hyperglycemic stage in a high risk genetically predisposed autoimmune suspected patient which may at least in part help to achieve new therapeutic approaches and help in halting the progression to end stage pancreatic disease (ESPD) known as diabetes mellitus. In this review we are going to emphasize the predictive role biopsy of the pancreas can build up a solid gold standard tool in diagnosis, stage and therapeutically follow up autoimmune diabetes mellitus.
Investigation of Irrigation Influence by Domestic Wastewater on Soil Characteristics
Fayaz Aghayari,Hossein Hassanpour Darvishi
Research Journal of Applied Sciences, Engineering and Technology , 2012,
Abstract: To investigate the beneficial impacts of wastewater on soil properties, we conducted an experiment in the lysimeter by measuring certain features essentially related to soil characteristics. Our objectives in this study were (i) the wastewater infiltration by soil and (ii) the effect of wastewater on soil properties. In this experiment, 9 lysimeter were used, 1, 2 and 3 lysimeters irrigated by domestic wastewater. Then, first drainage water accumulated from these lysimeters and 4, 5 and 6 lysimeters irrigated by this water and secondary drainage water accumulated from upon lysimeters. In order to comparison soil properties, 7, 8 and 9 lysimeters irrigated by normal water and finally, soil and water properties analyzed in each stage. The results showed that soil could filtering the wastewater and reduced BOD5 and COD of wastewater sorely. Also, irrigation with wastewater increased nutritive elements in soil that can be source of nutrition for plants. Our findings may give applicable advice to commercial farmers and agricultural researchers for management and proper use of water.
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