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Search Results: 1 - 10 of 815 matches for " Ebrahim Farshidi "
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A New Approach to Complex Bandpass Sigma Delta Modulator Design for GPS/Galileo Receiver  [PDF]
Nima Ahmadpoor, Ebrahim Farshidi
Circuits and Systems (CS) , 2012, DOI: 10.4236/cs.2012.31006
Abstract: In this paper, new complex band pass filter architecture for continuous time complex band pass sigma delta modulator is presented. In continuation of paper the modulator is designed for GPS and Galileo receiver. This modulator was simulated in standard 0.18 μm CMOS TSMC technology and has bandwidth of 2MHz and 4MHz for GPS and Galileo centered in 4.092 MHz. The dynamic range (DR) is 56.5/49 dB (GPS/Galileo) at sampling rate of 125 MHz. The modulator has power consumption of 4.1 mw with 3 V supply voltage.
An Analog Template-Based Classifier Using MOS Translinear Loops
Ebrahim Farshidi
Active and Passive Electronic Components , 2011, DOI: 10.1155/2011/192818
Abstract: An analog template matching pattern classifier circuit based on a new synthesis of Euclidean distance calculation is presented. It is composed of simple two-quadrant squarer/divider blocks. The circuit employs MOSFETs that operate in strong inverted saturation region performing electronically simulated translinear loop. The converter features very low supply voltage (0.9?V), immune from body effect, two-quadrant input current, large dynamic range, and low circuit complexity. The circuit was successfully applied to the recognition of some simple patterns. Simulation results by HSPICE show high performance in the separation of circuit and confirm the validity of the proposed technique. 1. Introduction Classification algorithm as a key function in information processing is used for analyzing groups of vector data. In fact, this algorithm is employed to find optimum prototype vector, from which the input vector is compared. There are two ways to implement classifier. One is employing digital computer, and the other is using analog circuits. Analog implementation of classification algorithm holds a series of advantages over digital implementation. The complexity of analog circuit blocks required to implement such systems is in general lower when compared with digital counterpart, and, additionally, A/D and D/A interfaces towards sensors and actuators are not needed. Moreover, better performances can be obtained in terms of velocity of signal processing, by fully exploiting the capability of analog circuits to implement parallel processing. Because, it would be intolerably time consuming when the number of template patterns becomes quite large and the problem is in excess of even the state-of-the-art computer technologies. Hence, analog implementation employing parallel very-large-scale integration (VLSI) architectures is desired for real-time classifier circuits. An attractive method to implement classification algorithm is employing Euclidean distance calculator. Recently, some analog integrated forms of Euclidean distance calculator have been proposed [1–6]. They can be used in classifications algorithms to measure how close an input pattern is to the prototype patterns. One attempt is to design vector summation circuit in voltage-mode approach based on the bipolar dynamic translinear implementation [1]. However, in many situations, particularly in mixed A/D systems, it is desirable to implement the circuits in MOS technology [2]. But, in traditional voltage-mode architectures, the supply voltage level reduction has a clear impact on the dynamic range of
A Double Heterostructure Multiplication Region in AlGaN Based SAGCM Avalanche Photodiode  [PDF]
Maryam Bagheriyeh-Behbahani, Mohammad Soroosh, Ebrahim Farshidi
Optics and Photonics Journal (OPJ) , 2017, DOI: 10.4236/opj.2017.710015
Abstract: In this study, separate absorption, grading, charge, and multiplication (SAGCM) avalanche photodiode (APD) with double heterojunction AlN/AlxGa1-xN/GaN in multiplication region were designed to reduce excess noise using Monte Carlo simulation. The multiplication region was broken to three different regions and tried to enhance localization of the first and second impact ionization events at near the heterojunctions. The excess noise of the proposed structure, for high gains, was 64% smaller than that of the fabricated standard AlGaN-APDs.
The Incidence of GI Complications in Patients with Leukemia During Chemotherapy
S Partovi,A Banihashem,F Farshidi
Iranian Journal of Pediatrics , 2004,
Abstract: Background: Acute leukemia is a common malignancy in childhood that is now curable with chemotherapy. The use of chemotherapeutic agents has numerous complications. We studied the incidence of gastrointestinal complications and its relation to specific phases of treatment. Material and method: In a cross-sectional study we examined 75 patients with acute leukemia who were treated with chemotherapy (Oct 2003 – Aug 2004) in Sheikh Hospital in Mashad/Iran. These patients had at least one GI complication caused by chemotherapy. The data was collected using a questionnaire. Results: The most common complications were oral ulcers (56%) and odinophagia (25.3%). The mean age of patients with diarrhea (p=0.018) and abdominal distention (p=0.008) was considerably higher than of other patients and it was significantly lower in patients with odinophagia (p=0.001); perioral ulcers (p=0.017), diarrhea (p=0.045), nausea and vomiting (p=0.031) and oral aphthes (p=0/043) were notably more common during the first phase of modified BFM Protocol for ALL treatment. Conclusion: The age of the patient and the phase of treatment have significant statistical relation with GI complications.
Microstructure evolution of a recycled Al–Fe–Si–Cu alloy processed by tube channel pressing
M. H. Farshidi,M. Rifai,H. Miyamoto
- , 2018, DOI: https://doi.org/10.1007/s12613-018-1668-6
Abstract: Although excellent recyclability is one of the advantages of Al alloys, a recycling process can reduce different properties of these alloys by adding coarse AlFeSi particles into the alloys’ microstructures. One of the well-known methods for modifying the microstructure of metallic materials is the imposition of severe plastic deformation (SPD). Nevertheless, the microstructure evolutions of recycled Al alloys containing extraordinary fractions of AlFeSi particles during SPD processing have seldom been considered. The aim of the present work is to study the microstructure evolution of a recycled Al–Fe–Si–Cu alloy during SPD processing. For this purpose, tubular specimens of the mentioned alloy were subjected to different numbers of passes of a recently developed SPD process called tube channel pressing (TCP); their microstructures were then studied using different techniques. The results show that coarse AlFeSi particles are fragmented into finer particles after processing by TCP. However, decomposition and dissolution of AlFeSi particles through TCP processing are negligible. In addition, TCP processing results in an increase in hardness of the alloy, which is attributed to the refinement of grains, to an increase of the dislocation density, and to the fragmentation of AlFeSi particles.
Effect of Hot Accumulative Roll Bonding Process on the Mechanical Properties of AA5083  [PDF]
Hassan Sheikh, Ebrahim Paimozd
Open Journal of Metal (OJMetal) , 2011, DOI: 10.4236/ojmetal.2011.11002
Abstract: In this work, accumulative roll bonding (ARB) process as a severe plastic deformation was applied on an AA5083 sheet up to 6 cycles at the temperature of 300℃ and at the strain rate of 50 s­‐1. The results of tensile tests show that the values of the yield stress and the ultimate tensile strength don't change considerably after 4 cycles. Also, transmission electron microscopy (TEM) micrograph confirmed that the microstructure has fine (sub) grains with the size of 200 nm - 400 nm.
Ochratoxin A in dried figs, raisings, apricots, dates on Iranian retail market  [PDF]
Ebrahim Rahimi, Amir Shakerian
Health (Health) , 2013, DOI: 10.4236/health.2013.512282
Abstract:

Ochratoxin A (OTA) is among the most important mycotoxins, and the International Agency for Research on Cancer (IARC) classifies it as possibly carcinogenic to humans (group 2B). A total of 121 samples of dried fruits from the central zone of Iran were analyzed for OTA by enzyme linked immunosorbent assay (ELISA) technique. The recovery percentages of OTA in spiked dried fruit samples at concentrations of 5, 10 and 20 ng/g were found to be 84.9%, 89.3% and 90.4% as mean, respectively. OTA was found in 20.7% of the analyzed samples by average concentration of 6.7 ± 3.9 ng/g. The incidence rates of OTA contamination in dried fig, raising, apricots, and date samples were 10.4%, 44.7%, 6.7% and 10.0%, respectively. The concentrations of OTA in 7.9% of contaminated dried raising samples and 2.1% of dried fig samples were higher than maximum tolerance limit accepted by European Union (10 ng/g). This value reflects that the analyzed samples have a minimal contribution to toxicological risk. To our best knowledge, the present study is the first report of the presence of OTA by ELISA in dried fruit samples in Iran.

 

Determination Cadmium and Lead Pollution Resources of Ardabil Plain Underground Waters  [PDF]
Saba Hajjabbari, Ebrahim Fataei
Open Journal of Ecology (OJE) , 2016, DOI: 10.4236/oje.2016.69053
Abstract: Underground water is among the most important sources of drinking water. The aim of this study was to determine the concentrations of heavy metals (cadmium, lead) in providing plain of Ardabil in 2015. This study was cross-sectional, drinking water samples from 100 wells were prepared according to standard procedures. The dimensions of 350 × 350 meter grid station via a station in the network were determined by atomic absorption spectrometry AAS analysis of samples. The data obtained were analyzed using SPSS software. The average concentrations of lead, cadmium in groundwater wells in the area were also studied. The mean concentrations measured in the majority of groundwater wells in the plain of Ardabil lower than the allowed amount were designated according to a national standard.
Study on the Effects of Work Teams on Human Resources Excellence  [PDF]
Ebrahim Kalani, Ehsan Kamrani
Journal of Human Resource and Sustainability Studies (JHRSS) , 2017, DOI: 10.4236/jhrss.2017.51002
Abstract: The conception and use of work teams have been one of the main subjects of management researches for the last few decades and in the past years many developments have happened in the kinds and usage of them, which have improved the condition of organizations and human resources management. Our objective in this paper is to observe the formation of work teams and how they affect human resources excellence. Finding new and creative solutions for todays intricate situations is becoming more and more difficult and employees can’t solve them on their own anymore and this shows and bolds the importance of teamwork and forming work teams. The main objective however in this paper is to evaluate the effect of 5 main characteristics of work teams (which are team structure, leadership, control, mutual support and communication) on the 3 main characteristics of human resources excellence (which are delegation, motivation and team work) in Torang Darya Shipping Company. To do so, 200 personnel at the department were randomly selected from 450 personnel by Cochran sample size formula and answered to the research made questionnaire derived from[1][2] and[3]. The content validity of the questionnaire has been confirmed by the experts and academicians and the reliability has also been confirmed
Pathology of Barriers to Sharing Knowledge in Project Management and Ranking Them by AHP Method  [PDF]
Ebrahim Kalani, Ehsan Kamrani
Journal of Human Resource and Sustainability Studies (JHRSS) , 2017, DOI: 10.4236/jhrss.2017.51007
Abstract: Although knowledge management is a necessary part of strategic development of organizations, resources and improvement in competition, since it is always seen just as a temporary solution, most of related experiences have faced failure. Moreover since projects are mostly temporary and after they are done some of the main team members leave the company, this means the knowledge goes with them so this will cost future projects more money and time. In the present study we will try to find the main barriers for knowledge transmission and to rank them by statistical method of Analytic Hierarchy Process (AHP). In the end it comes to conclusion that despite the existence of the Project Management Body of Knowledge (PMBOK), it has been overlooked. The main barriers are the lack of organizational culture of preserving and sharing the knowledge and lack of trust and appreciation for using it throughout the company.
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