Neutronic assessment of BDBA scenario at the end of Isfahan MNSR core life

M. Ahmadi,A. Pirouzmand,A. Rabiee 한국원자력학회 2018 Nuclear Engineering and Technology Vol.50 No.7

The present study aims to assess the excess induced reactivity in a Miniature Neutron Source Reactor(MNSR) for a Beyond Design Basis Accident (BDBA) scenario. The BDBA scenario as defined in the SafetyAnalysis Report (SAR) of the reactor involves sticking of the control rod and filling of the inner and outerirradiation sites with water. At the end of the MNSR core life, 10.95 cm of Beryllium is added to the top ofthe core as a reflector which affects some neutronic parameters such as effective delayed neutronsfraction (beff), the reactivity worth of inner and outer irradiation sites that are filled with water and thereactivity worth of the control rod. Given those influences and changes, new neutronic calculations arerequired to be able to demonstrate the reactor safety. Therefore, a validated MCNPX model is used tocalculate all neutronic parameters at the end of the reactor core life. The calculations show that theinduced reactivity in the BDBA scenario increases at the end of core life to 7.90 ± 0.01 mk which issignificantly higher than the induced reactivity of 6.80 mk given in the SAR of MNSR for the samescenario but at the beginning of the core's life. Also this value is 3.90 mk higher than the maximumallowable operational limit (i.e. 4.00 mk).

Development of a 3D thermohydraulic-neutronic coupling model for accident analysis in research miniature neutron source reactor (MNSR)

M. Ahmadi,A. Rabiee,A. Pirouzmand 한국원자력학회 2019 Nuclear Engineering and Technology Vol.51 No.7

To accurately analyze the accidents in nuclear reactors, a thermohydraulic-neutronic coupling calculation is required to solve fluid dynamics and nuclear reactor kinetics equations in fine cells simultaneously and evaluate the local effects of neutronic and thermohydraulic parameters on each other. In the present study, a 3D thermohydraulic-neutronic coupling model is developed, validated and then applied for Isfahan MNSR (Miniature Neutron Source reactor) safety analysis. The proposed model is developed using FLUENT software and user defined functions (UDF) are applied to simulate the neutronic behavior of MNSR. The validation of the proposed model is first evaluated using 1mk reactivity insertion experiment into Isfahan MNSR core. Then, the developed coupling code is applied for a design basis accident (DBA) scenario analysis with the insertion of maximum allowed cold core reactivity of 4 mk. The results show that the proposed model is able to predict the behavior of the reactor core under normal and accident conditions with a good accuracy.

The Availability of Energy and Protein, with Respect to Uric Acid, of Yellow-seeded Rapeseed Meal in Broiler Diets

Saki, A.A.,Mahmoudi, H.,Tabatabaei, M.M.,Ahmadi, A. Asian Australasian Association of Animal Productio 2008 Animal Bioscience Vol.21 No.11

Experiments were conducted to evaluate the nutritional value of yellow-seeded rapeseed meal (YRSM). In the first experiment nutrient retention was recorded by 48 Arbor Acres-broiler chickens (28-d old) to determine AMEn (nitrogen-corrected apparent metabolizable energy), coefficient of apparent protein digestibility based on ileal digesta nitrogen, excreta nitrogen and uric acid nitrogen. The second experiment was carried out with 304 Arbor Acres-broiler chickens to compare effects of SBM (soybean meal) and YRSM on performance, carcass and digestive tract status. In the control treatment, SBM was replaced by graded levels of YRSM at 15, 22.5 and 30% of diet. Digestibility of YRSM protein was significantly lower (p<0.001) than SBM protein. The protein digestibility based on ileal measurement was significantly higher (p<0.001) than protein digestibility from excreta samples. There was no significant difference (p>0.001) between ileal and excreta digestibility of protein based on uric acid. AMEn as a fraction of gross energy was 0.54 in SBM and 0.45 in YRSM. With the exception of 30% YRSM, other YRSM treatments resulted in major effects on length and weight of the gastrointestinal tract. The results of this study have shown no adverse effect on performance as well as protein digestibility and energy value in response to replacement of SBM by YRSM with the exception of 22.5 and 30% YRSM.

Application of Statistical Experimental Design for Optimization of Silver Nanoparticles Biosynthesis by a Nanofactory Streptomyces viridochromogenes

Noura El-Ahmady El-Naggar,Nayera A.M. Abdelwahed 한국미생물학회 2014 The journal of microbiology Vol.52 No.1

Central composite design was chosen to determine the combined effects of four process variables (AgNO3 concentration,incubation period, pH level and inoculum size) on the extracellular biosynthesis of silver nanoparticles (AgNPs) by Streptomyces viridochromogenes. Statistical analysis of the results showed that incubation period, initial pH level and inoculum size had significant effects (P 0.05) on the biosynthesis of silver nanoparticles at their individual level. The maximum biosynthesis of silver nanoparticles was achieved at a concentration of 0.5% (v/v) of 1 mM AgNO3, incubation period of 96 h, initial pH of 9 and inoculum size of 2% (v/v). After optimization, the biosynthesis of silver nanoparticles was improved by approximately 5-fold as compared to that of the unoptimized conditions. The synthetic process of silver nanoparticle generation using the reduction of aqueous Ag+ ion by the culture supernatants of S. viridochromogenes was quite fast, and silver nanoparticles were formed immediately by the addition of AgNO3 solution (1 mM) to the cell-free supernatant. Initial characterization of silver nanoparticles was performed by visual observation of color change from yellow to intense brown color. UV-visible spectrophotometry for measuring surface plasmon resonance showed a single absorption peak at 400 nm, which confirmed the presence of silver nanoparticles. Fourier Transform Infrared Spectroscopy analysis provided evidence for proteins as possible reducing and capping agents for stabilizing the nanoparticles. Transmission Electron Microscopy revealed the extracellular formation of spherical silver nanoparticles in the size range of 2.15–7.27 nm. Compared to the cell-free supernatant, the biosynthesized AgNPs revealed superior antimicrobial activity against Gram-negative, Gram-positive bacterial strains and Candida albicans.

Bioactive Compounds and Chemical Biology : Fabrication of Biogenic Antimicrobial Silver Nanoparticles by Streptomyces aegyptia NEAE 102 as Eco-Friendly Nanofactory

( Noura El-ahmady El-naggar ),( Nayera A M Abdelwahed ),( Osama M M Darwesh ) 한국미생물 · 생명공학회 2014 Journal of microbiology and biotechnology Vol.24 No.4

The current research was focused on the extracellular biosynthesis of bactericidal silver nanoparticles (AgNPs) using cell-free supernatant of a local isolate previously identified as a novel Streptomyces aegyptia NEAE 102. The biosynthesis of silver nanoparticles by Streptomyces aegyptia NEAE 102 was quite fast and required far less time than previously published strains. The produced particles showed a single surface plasmon resonance peak at 400 nm by UV.Vis spectroscopy, which confirmed the presence of AgNPs. Response surface methodology was chosen to evaluate the effects of four process variables (AgNO3 concentration, incubation period, pH levels, and inoculum size) on the biosynthesis of silver nanoparticles by Streptomyces aegyptia NEAE 102. Statistical analysis of the results showed that the linear and quadratic effects of incubation period, initial pH, and inoculum size had a significant effect (p < 0.05) on the biosynthesis of silver nanoparticles by Streptomyces aegyptia NEAE 102. The maximum silver nanoparticles biosynthesis (2.5 OD, at 400 nm ) was achieved in runs number 5 and 14 under the conditions of 1 mM AgNO3 (1-1.5% (v/v)), incubation period (72-96 h), initial pH (9-10), and inoculum size (2-4% (v/v)). An overall 4-fold increase in AgNPs biosynthesis was obtained as compared with that of unoptimized conditions. The biosynthesized silver nanoparticles were characterized using UV-VIS spectrophotometer and Fourier transform infrared spectroscopy analysis, in addition to antimicrobial properties. The biosynthesized AgNPs significantly inhibited the growth of medically important pathogenic gram-positive (Staphylococcus aureus) and gram-negative bacteria (Pseudomonas aeruginosa) and yeast (Candida albicans).

Analytical Discussion on Stochastic Hydrodynamic Modeling of Support Structure of HAWAII WTG Offshore Wind Turbine

Abaiee, M.M.,Ahmadi, A.,Ketabdari, M.J. Korean Society of Ocean Engineers 2015 Journal of advanced research in ocean engineering Vol.1 No.1

Floating structure such as tension leg platform, semi-submersible and spar are widely used in field of oil exploration and renewable energy system. All of these structures have the base cylinder support structure which have effective rule in overall dynamic of response. So the accurate and reliable modeling is needed for optimum design and understanding the physical background of these systems. The aim of this article is an analytical discussion on stochastic modeling of floating cylinder based support structure but an applicable one. Due to this a mathematical mass-damper-spring system of a floating cylinder of HAWAII WTG offshore wind as an applicable and innovative system is adopted to model a coupled degrees using random vibration in analytical way. A fully develop spectrum is adopted to solve the stochastic spectrum analytically by a proper approximation. Some acceptable assumption is adopted. The simplified but analytical and innovative hydrodynamic analysis of this study not only will help researcher to concentrate more physically on hydrodynamic analysis of floating structures but also can be useful for any quick, simplified and closed form analysis of a complicated problem in offshore engineering.

Impact of Non-obstructive left main disease on the progression of coronary artery disease: A PARADIGM substudy

Weir-McCall, Jonathan R.,Blanke, Philipp,Sellers, Stephanie L.,Ahmadi, Amir A.,Andreini, Daniele,Budoff, Matthew J.,Cademartiri, Filippo,Chinnaiyan, Kavitha,Choi, Jung Hyun,Chun, Eun Ju,Conte, Edoardo Elsevier 2018 Journal of cardiovascular computed tomography Vol.12 No.3

<P><B>Abstract</B></P> <P><B>Background</B></P> <P>The aim of the study is examine the impact of non-obstructive (<50%stenosis) left main (LM) disease on the natural history of coronary artery disease using serial coronary computed tomography angiography (CTA).</P> <P><B>Methods</B></P> <P>CTAs from the PARADIGM (Progression of atherosclerotic plaque determined by computed tomographic angiography imaging) study, a prospective multinational registry of patients who underwent serial CTA at a ≥2 year interval were analyzed. Those without evidence of CAD on their baseline scan were excluded, as were those with obstructive left main disease. Coronary artery vessels and their branches underwent quantification of: plaque volume and composition; diameter stenosis; presence of high-risk plaque.</P> <P><B>Results</B></P> <P>Of 944 (62 ± 9 years, 60% male) who had evidence of CAD at baseline, 444 (47%) had LM disease. Those with LM disease had a higher baseline plaque volume (194.8 ± 221mm3 versus 72.9 ± 84.3mm3, p < 0.001) and a higher prevalence of high-risk plaque (17.5% versus 13%, p < 0.001) than those without LM disease. On multivariable general linear model, patients with LM disease had greater annual rates of progression of total (26.5 ± 31.4mm3/yr versus 14.9 ± 20.1mm3/yr, p < 0.001) and calcified plaque volume (17 ± 24mm3/yr versus 7 ± 11mm3/yr, p < 0.001), with no difference in fibrous, fibrofatty or necrotic core plaque components.</P> <P><B>Conclusion</B></P> <P>The presence of non-obstructive LM disease is associated with greater rates of plaque progression and a higher prevalence of high-risk plaque throughout the entire coronary artery tree compared to CAD without LM involvement. Our data suggests that non-obstructive LM disease may be a marker for an aggressive phenotype of CAD that may benefit from more intensive treatment strategies.</P>

ACCESS TO JUSTICE AND ROLE OF THE LAWYER IN SOCIETY

A.M. Ahmadi 한국법학원 1991 저스티스 Vol.24 No.2

Minimal retraction of space-time and their foldings

A. E. El-Ahmady,H. Rafat 장전수학회 2010 Proceedings of the Jangjeon mathematical society Vol.13 No.3

In this article, we will be deduced the geodesics of space-time by using Lagrangian equations. The deformation retract of space-time onto itself and into a geodesics will be achieved. The concept of retraction and folding of zero dimension space-time will be obtained.The relation between limit of folding and retraction presented.

Fractal retraction of chaotic Narlikar and Karmarkar space

A. E. Al-Ahmady,? H. Rafat 장전수학회 2007 Advanced Studies in Contemporary Mathematics Vol.15 No.2

In this article we will introduce a new type of retraction in chaotic Narlikar and Karmarkar space. The geodesics of chaotic Narlikar and Karmarkar space will be deduced. The end of limit folding in chaotic Narlikar and Karmarkar space will be presented.