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Numerical investigation of the effect of the location of stern planes on submarine wake flow
Beigi, Shokrallah M.,Shateri, Alireza,Manshadi, Mojtaba D. Techno-Press 2020 Ocean systems engineering Vol.10 No.3
In the present paper, the effect of the location of stern planes on the flow entering the submarine propeller is studied numerically. These planes are mounted on three longitudinal positions on the submarine stern. The results are presented considering the flow field characteristics such as non-dimensional pressure coefficient, effective drag and lift forces on the stern plane, and the wake flow formed at the rear of the submarine where the propeller is located. In the present study, the submarine is studied at fully immersed condition without considering the free surface effects. The numerical results are verified with the experimental data. It is concluded that as the number of planes installed at the end of the stern section along the submarine model increases, the average velocity, width of the wake flow and its turbulence intensity formed at the end of the submarine enhance. This leads to a reduction in the non-uniformity of the inlet flow to the propulsion system.
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Mitra Beigi,Ensiyeh Karimi,Rasoul Abedi,Nooshin Kejani,Siamak Khorramymehr 국제무예학회 2024 International Journal of Martial Arts Vol.9 No.-
Biomechanical assessment of Taekwondo athletes’ motion is essential to improve their performance. It is well known that balance tasks such as Hakdariseogi are determinant techniques which affect the result of a competition. So the aim of this study is to compare biomechanical variables of the support leg during Hakdariseogi task between elite and non-elite taekwondo athletes. Eighteen taekwondo athletes including ten elite and eight non-elite were participated. Six high-speed motion cameras and one force plate were used to acquire kinematics and kinetics data. MATLAB R2017b was used to plot support leg’s joints curves. Statistical analysis was performed to compare variables between two mentioned groups.The average of joints’ angles in the elite group was significantly more than non-elite group during the movement and balance phases (p<0.05).The amount of knee angular velocity in elite athletes was meaningfully higher than non-elite athletes during the movement phase (p<0.05). Also, the average amount of hip and ankle moments was greater in elite athletes during balance phase (p<0.05).There were no meaningful differences in other moment variables between elite and non-elite athletes (p>0.05).In some conditions, elites had more stability with greater angles and moments in the support leg’s joints. So they could perform Hakdariseogi task more quickly or in higher range of values than non-elite group and also generate more muscle activity due to the greater net joint moments, to create more joint moments for better control and stability, and neutralizing the external moments (such as ground reaction moments).
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Prolonged semen incubation alters the biological characteristics of human spermatozoa
Sayed Abbas Datli Beigi,Mohammad Ali Khalili,Ali Nabi,Mohammad Hosseini,Abolghasem Abbasi Sarcheshmeh,Mojdeh Sabour The Korean Society for Reproductive Medicine 2022 Clinical and Experimental Reproductive Medicine Vol.49 No.4
Objective: The present study assessed the biological characteristics of human spermatozoa at different time intervals (0, 1, 1.5, and 2 hours) after incubation at 37℃. Methods: Twenty-five normozoospermic semen samples were incubated at 37℃. Incubation was performed at four time intervals of 0 (after liquefaction), 1, 1.5, and 2 hours. The samples were evaluated for sperm parameters at each time interval. Results: The rate of sperm progressive motility decreased at 1.5 hours compared to 0 hours as well as 2 hours compared to 1 hour and 0 hours. The rate of non-motile spermatozoa also decreased after 2 hours compared to after 0 hours. No significant changes were observed in sperm viability (p=0.98) and non- progressive motility (p=0.48) at any time intervals. Abnormal sperm morphology increased at 1.5 hours of incubation time (p<0.001). No significant changes were observed in DNA fragmentation at 1 hour compared to 0 hours (median [interquartile range]: 19.5 [4] vs. 19 [4]), as well as at 1.5 hours compared to 1 hour (20 [5]). However, a significant increase in DNA fragmentation was observed at 1.5 hours compared to 0 hours. The mitochondrial membrane potential decreased remarkably after 1 hour of incubation time. No significant differences were observed in the acrosome reaction or malonaldehyde levels at any time point (p=0.34 and p=0.98, respectively). Conclusion: The incubation of normozoospermic samples before use in assisted reproductive technology should be less than 1.5 hours to minimize the destructive effects of prolonged incubation time on general and specific sperm parameters.
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Dual-Halbach Array Permanent Magnet Tubular Generator for Free-Piston Generator
Hassan Moradi Cheshmeh Beigi,Sohrab Akbari 한국자기학회 2015 Journal of Magnetics Vol.20 No.4
In this study, we describe the effects of changing the magnet shape of permanent magnets (PMs) in a rotor Halbach-array PM generator for reciprocating free piston generator applications. More specifically, the rectangular-shaped magnets were replaced by the trapezoidal-shaped magnets. The initial design, an analytical magnetic field solution of rectangular shaped magnets, is presented and air-gap magnetic flux density and thrust force were estimated. The results were compared to the finite element analysis (FEA) showing excellent agreement. Using FEA, the effect of the shape of the magnets on the flux density and thrust force waveforms is analyzed. Moreover, the proportion of the Halbach array in the machine was optimized by the means of a parametric search. The results obtained from the analytical calculations and FEA were validated by comparing to those of Radial-array PM generator.
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Jalal Aala,Asghar Beigi Harchegani,Hanieh Akhlaghi Monsef,Zhaleh Mohsenifar,Pirooz Ebrahimi,Mohammad Reza Parvizi 환경독성보건학회 2021 환경독성보건학회지 Vol.36 No.4
This study aimed to consider the expression of Nrf2, NLRP3 and caspase 1 genes, as well as oxidative stress, and the protective role of N-acetyl cysteine (NAC) in the liver of rats treated with cadmium (Cd). Male rats were randomly divided into five groups including G1 (control), G2 (single dose of Cd), G3 (continuous dose of Cd), G4 (single dose of Cd + NAC), and G5 (continuous dose of Cd + NAC). Levels of malondialdehyde (MDA) and total antioxidant capacity (TAC) were measured. Expression of Nrf2, NLRP3 and caspase 1 genes was considered using RT-PCR. NAC treatments significantly improved TAC, but decreased MDA values in rats that exposed to continuous dose of Cd (p<0.05). Exposure to continuous dose of Cd caused a significant decrease in Nrf2 expression by 2.46-fold (p<0.001), but enhanced expression of NLRP3 and Caspase 1 genes by 3.13-fold and 3.16-fold), respectively (p<0.001). Compared to rats that treated to continuous dose of Cd, NAC supplementation enhanced the expression of Nrf2 by 1.67-fold (p<0.001) and reduced the expression of NLRP3 and Caspase 1 genes by 1.39-fold (p<0.001) and 1.58-fold (p<0.001), respectively. Down-regulation of Nrf2 and overexpression of NLRP3 and caspase 1 seems to be one of the main mechanisms of Cd toxicity on liver tissue. NAC protects liver tissue against Cd-induced oxidative injuries via enhancement of Nrf2 expression and reduction of NLRP3 and caspase 1 genes.
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Assessing Lifecycle Success of Petrochemical Projects–based on Client’s Viewpoint
M. Shariatfar,H. Beigi,M. M. Mortaheb 대한토목학회 2019 KSCE Journal of Civil Engineering Vol.23 No.1
For the last couple of decades, researchers/managers have realized that the traditional success criteria known as golden triangle (time, cost, quality) are not adequate measures to align a project with the long term success trend of a company. The perception of project success may differ from one industry to another or from one stakeholder (client, contractor, etc.) to other. Petrochemical projects are of high complexity and a vast variety of parameters needs to be monitored in order to produce on spec products according to the customer requirements and market dynamic changes. To be successful in such complex projects, it is required to be successful in every phase of the project lifecycle. In this study, project success has been linked to four dimensions (efficiency, business success, impact and future preparation) and is investigated from client's point of view. Based on a list of success criteria, previously recognized important by other researchers, a set of novel categorizations of the success criteria has been developed, called Success Breakdown Structure (SBS). The relative importance of each success criterion is measured by means of a survey questionnaire. It was found that almost all success criteria are important for clients and the efficiency dimension of success plays the most important role in the long term success achievement in client’s organization.
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Gholamreza Abdollahzadeh,Sakhi Yapang Gharavi,Morteza Hoseinali Beigy 한국강구조학회 2015 International Journal of Steel Structures Vol.15 No.4
Through this study, a method is presented to estimate moment-rotation (M-) curve of I beam-to-the concrete filled tube (CFT) connections. This method is based on the components method in which components are analyzed and modeled as different mechanical models. These components are considered as springs with specific mechanical properties of stiffness, strength, and rigid bars. Their force-displacement relationship is assumed bi-linear and 3-linear. The connection behavior is assumed through assembling the stiffness of different components. In this study, connection of I beam-to-CFT column with bolted endplate connection under monotonic loading, which has been tested in the laboratory, is evaluated. It must be mentioned that those bolts which penetrated into the column depth have been used in order to create continuity between flanges of the column. The suggested method has been compared with the experimental test and the advanced finite element model in terms of stiffness, strength, and rotational capacity; moreover, its operation was satisfactory.
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Maryam Yousefi,Majid Abdouss,Ali Akbar Miran Beigi,Ali Naseri 한국화학공학회 2017 Korean Journal of Chemical Engineering Vol.34 No.9
A series of ionic liquids based on Octyl and Decyl methylimidazolium with different anions such as chloride, glycinate, dihydrogen phosphate and trihydrogen diphosphate, were synthesized and characterized by 1HNMR and elemental analysis. IL containing trihydrogen diphosphate anion, was synthesized for the first time. Physicochemical properties, including density, viscosity, surface tension, refractive index, and pH, were measured in temperature range 283.15 to 363.15 K and atmospheric pressure. The effects of temperature, alkyl chain, and anion type on physicochemical properties were investigated. The results revealed that the physicochemical properties decreased as a function of temperature. Unlike viscosity, other properties, such as density, surface tension, refractive index and pH values, decreased, while alkyl chain length increased. Understanding ILs properties and determining their unique abilities helps researchers to use them in new applications. These long alkyl chain ILs, are being used as surfactants to reduce Oil/Water interfacial tension in EOR process.
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