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匹配条件: “Saeid Dashti” ,找到相关结果约696条。
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Evaluation of Internal Cracks and Collapse in Poplar Wood (Populus nigra) during a Conventional Drying Process with Ultrasonic Inspection
Saeid ESHAGHI,Hadi DASHTI,Mahdi SHAHVERDI
Notulae Scientia Biologicae , 2012,
Abstract: In this research, internal cracks and collapse of wood, formed during drying process, were measured using ultrasonic inspection. For this purpose, seven poplar (Populus nigra) small blocks were dried, according to a time-based schedule. Ultrasonic waves’ propagation velocity was measured at both parallel and perpendicular to grain directions, using Sylvatest ultrasound device, during kiln drying process. Results showed that in all dried blocks, waves’ propagation velocity in the parallel direction was higher than in the perpendicular direction to grain. Ultrasonic waves’ propagation test for non-destructive identification of internal cracks, which occurs in wood during drying process in the parallel direction, was more successful compared to the perpendicular direction. Using ultrasonic waves’ propagation test for detection of collapse that occurs in wood during drying process was not useful.
Stabilization students' awareness based on training classes in EMS
Arezo Karampourian,Nahid Mohamadi,Behzad Imani,Saeid Dashti
Pajouhan Scientific Journal , 2013,
Abstract: Introduction: The professional ethics in the medical field is an important concept. Understanding of EMS with professional ethic provide better services and to minimum professional stress. The group discussion method in the teaching of professional ethics is efficiency. The authors benefited of the method to evaluate the awareness of the ethical issues based on training classes.Material and Methods: The study was Cross - sectional. The study population included all of the students of EMS in the final year. Number of samples was 30 and method of sampling was the census method. After of expression course plan pre test was taken and after the end of class final examination was taken. Rate of knowledge of student was assessed after 3 semesters and data obtained were analyzed by software SPSS 16.Results: Rate of knowledge of students before teaching were 97% weak and 3% moderate. The scores of Students was between 20-14 and the mean of was 16.58. Results after 3 terms were this: The average student score 24/69, most samples (80%) have a high awareness and 20% had poor knowledge.Conclusion: The ministry of health policy is edification prior knowledge. The students' awareness of duty was high (80%), in the legal field was very weak and in some areas, such as respect, altruism was moderate.
Comparison of multiplex PCR with serogrouping and PCR-RFLP of fliC gene for the detection of enteropathogenic Escherichia coli (EPEC)
Bouzari, Saeid;Aslani, Mohammad M;Oloomi, Mana;Jafari, Anis;Dashti, Amir;
Brazilian Journal of Infectious Diseases , 2011, DOI: 10.1590/S1413-86702011000400011
Abstract: enteropathogenic escherichia coli (epec) comprise one of the six categories of diarrhoeagenic e. coli (dec). epec is subgrouped into typical (tepec) and atypical (aepec). the identification of dec cannot be based only on cultural and biochemical criteria, since they are indistinguishable from the non-pathogenic e. coli commonly found in human feces. several pcr methods, with both single and multiple target genes, have been reported for detecting the different dec pathotypes. in the present study five hundred e. coli isolates from children with diarrhea were subjected into multiplex pcr. furthermore the strains were typed serologically with o antisera and their flic gene was characterized by pcr-rflp. the results obtained revealed that overall 41 (8.2%) isolates could be detected as epec by this multiplex pcr assay. of these isolates; 27 (66%) were typical (escv+, bfp+) and 14 (34%) atypical epec (escv+, bfp-). none of these 41 isolates contained the stx1 and stx2 genes. among 37 (90%) typeable strains, nine different serogroups were present. the most common serogroups were o111, followed by o86, o55 and o119 and 10 different h types were found among these isolates. the multiplex pcr assay was found to be rapid and reliable in comparison to serological test; especially when screening the large number of isolates.
Optimization of Recloser Placement to Improve Reliability by Genetic Algorithm  [PDF]
Nematollah Dehghani, Rahman Dashti
Energy and Power Engineering (EPE) , 2011, DOI: 10.4236/epe.2011.34061
Abstract: In this paper, a simple method for placing an optimal number of recloser is presented. The algorithm is solved using genetic algorithm as the optimization method. The majority of outage events experienced by customers are due to electrical distribution failures. Increasing network reliability is a necessity in order to reduce interruption events. Distribution network automation can trim down outage events and increase system reliability. Network automation has to be done using optimization approaches. Genetic Algorithm (GA) is a relatively new technique used in power systems optimization problems. Distribution network automation is one of the aspects tackled using GA. However ,the methodologies used to improve the reliability of radial distribution feeders are reviewed. The reliability improvement are demonstrated for typical distribution feeder layouts. determined. The method enjoys the simplicity of conFigure uration, accuracy of the results and reduction of the time consuming. The obtained results also show the applicability of the algorithm
Determination of Trace Amounts of Lead by Modified Graphite Furnace Atomic Absorption Spectrometry after Liquid Phase Microextraction with Pyrimidine-2-thiol  [PDF]
Saeid Nazari
American Journal of Analytical Chemistry (AJAC) , 2011, DOI: 10.4236/ajac.2011.27087
Abstract: The liquid phase microextraction (LPME) was combined with the modified Graphite furnace atomic absorption spectrometry (GF-AAS) for determination of lead in the water and solid samples. In a preconcentration step, lead was extracted from a 2 ml of its aqueous sample in the pH = 5 as lead-Pyrimidine-2-thiol cationic complex into a 4 µl drop of 1,2 dichloroethane and ammonium tetraphenylborate as counter ion immersed in the solution. In the drop, the lead-Pyrimidine-2-thiol ammonium tetraphenylborate ion associated complex was formed. After extraction, the microdrop was retracted and directly transferred into a graphite tube modified by [W.Pd.Mg] (c). Some effective parameters on extraction and complex formation, such as type and volume of organic solvent, pH, concentration of chelating agent and counter ion, extraction time, stirring rate and effect of salt were optimized. Under the optimum conditions, the enrichment factor and recovery were 525% and 94%, respectively. The calibration graph was linear in the range of 0.01 - 12 µg?L–1 with correlation coefficient of 0.9975 under the optimum conditions of the recommended procedure. The detection limit based on the 3Sb criterion was 0.0072 µg?L–1 and relative standard deviation (RSD) for ten replicate measurement of 0.1 µg?L–1 and 0.4 µg?L–1 lead was 4.5% and 3.8% respectively. The characteristic concentration was 0.0065 µg?L–1 equivalent to a characteristic mass of 26 fg. The results for determination of lead in reference materials, spiked tap water and seawater demonstrated the accuracy, recovery and applicability of the presented method.
Considering Adelman's Shortest Permutation Strings
Hesam Dashti
Mathematics , 2010,
Abstract: In this report, we consider Adelman's algorithm for generating shortest permutation strings. We introduce a new representation approach which reveals some properties of Adelman's algorithm.
Adaptive System for Assigning Reliable Students’ Letter Grades—A Computer Code  [PDF]
Saeid A. Alghamdi
Intelligent Information Management (IIM) , 2010, DOI: 10.4236/iim.2010.210066
Abstract: The availability of automated evaluation methodologies that may reliably be used for determining students’ scholastic performance through assigning letter grades are of utmost practical importance to educators, students, and do invariably have pivotal values to all stakeholders of the academic process. In particular, educators use letter grades as quantification metrics to monitor students’ intellectual progress within a framework of clearly specified learning objectives of a course. To students grades may be used as predictive measures and motivating drives for success in a study field. However due to numerous objective and subjective variables that may by be accounted for in a methodological process of assigning students’ grades, and since such a process is often tainted with personal philosophy and human psychology factors, it is essential that educators exercise extra care in maximizing positive account of all objective factors and minimizing negative ramifications of subjectively fuzzy factors. To this end, and in an attempt to make assigning students’ grades more reliable for assessing true-level of mastering specified learning outcomes, this paper will: i) provide a literature review on previous works on the most common methods that have traditionally been in use for assigning students’ grades, and a short account of the virtues and/or vices of such methods, and ii) present a user-friendly computer code that may be easily adapted for the purpose of assigning students’ grades. This would relieve educators from the overwhelming concerns associated with mechanistic aspects of determining educational metrics, and it would allow them to have more time and focus to obtain reliable assessments of true-level of students’ mastery of learning outcomes by accounting for all possible evaluation components.
Effect of Oscillating Jet Velocity on the Jet Impingement Cooling of an Isothermal Surface  [PDF]
Nawaf H. SAEID
Engineering (ENG) , 2009, DOI: 10.4236/eng.2009.13016
Abstract: Numerical investigation of the unsteady two-dimensional slot jet impingement cooling of a horizontal heat source is carried out in the present article. The jet velocity is assumed to be in the laminar flow regime and it has a periodic variation with the flow time. The solution is started with zero initial velocity components and constant initial temperature, which is same as the jet temperature. After few periods of oscillation the flow and heat transfer process become periodic. The performance of the jet impingement cooling is evaluated by calculation of friction coefficient and Nusselt number. Parametric study is carried out and the results are presented to show the effects of the periodic jet velocity on the heat and fluid flow. The results indicate that the average Nusselt number and the average friction coefficient are oscillating following the jet velocity oscillation with a small phase shift at small periods. The simulation results show that the combination of Re =200 with the period of the jet velocity between 1.5 sec and 2.0 sec and high amplitude (0.25 m/s to 0.3 m/s) gives average friction coefficient and Nusselt number higher than the respective steady-state values.
Prevalence of smoking among universities students of Shahroud in 2010  [PDF]
Saeid Nazemi, Reza Chaman
Open Journal of Preventive Medicine (OJPM) , 2012, DOI: 10.4236/ojpm.2012.22034
Abstract: This study in 2010 determined the prevalence of smoking and its associated factors among universities students in Shahroud located in the North Eastern of Iran. 1800 students were selected randomly among 20000 students of Shahroud universities, to complete a questionnaire Which was prepared based on the Global Youth Tobacco Survey. The prevalence of current smoking was 20% (80% male and 20% female). The most important factors in the tendency to smoking were: friends smoking, stress, separation from family and fun.
Simulation of Dynamic Response of Small Wind-Photovoltaic-Fuel Cell Hybrid Energy System  [PDF]
Saeid Esmaeili, Mehdi Shafiee
Smart Grid and Renewable Energy (SGRE) , 2012, DOI: 10.4236/sgre.2012.33027
Abstract: Renewable energy systems are of importance as being modular, nature-friendly and domestic. Among renewable energy systems, a great deal of research has been conducted especially on photovoltaic effect, wind energy and fuel cell in the recent years. This paper describes dynamic modeling and simulation results of a small wind-photovoltaic-fuel cell hybrid energy system. The hybrid system consists of a 500 W wind turbine, a photovoltaic, a proton exchange membrane fuel cell (PEMFC), ultracapacitors, an electrolyzer, a boost converter, controllers and a power converter that simulated using MATLAB solver. This kind of hybrid system is completely stand-alone, reliable and has high efficiency. In order to minimize sudden variations in voltage magnitude ultracapacitors are proposed. Power converter and inverter are used to produce ac output power. Dynamics of fuel-cell component such as double layer capacitance are also taken into account. Control scheme of fuel-cell flow controller and voltage regulators are based on PID controllers. Dynamic responses of the system for a step change in the electrical load and wind speed are presented. Results showed that the ability of the system in adapting itself to sudden changes and new conditions. Combination of PV and wind renewable sources is made the advantage of using this system in regions which have higher wind speeds in the seasons that suffers from less sunny days and vice versa.
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