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Numerical calculations of aerodynamic performance for ATM train at crosswind conditions
Rezvani, Mohammad Ali,Mohebbi, Masoud Techno-Press 2014 Wind and Structures, An International Journal (WAS Vol.18 No.5
This article presents the unsteady aerodynamic performance of crosswind stability obtained numerically for the ATM train. Results of numerical investigations of airflow past a train under different yawing conditions are summarized. Variations of occurrence flow angle from parallel to normal with respect to the direction of forward train motion resulted in the development of different flow patterns. The numerical simulation addresses the ability to resolve the flow field around the train subjected to relatively large yaw angles with three-dimensional Reynolds-averaged Navier-Stokes equations (RANS). ${\kappa}-{\varepsilon}$ turbulence model solved on a multi-block structured grid using a finite volume method. The massively separated flow for the higher yaw angles on the leeward side of the train justifies the use of RANS, where the results show good agreement with verification results. A method of solution is presented that can predict all aerodynamic coefficients and the wind characteristic curve at variety of angles at different speed.
Rezvani, Fariba,Sarrafzadeh, Mohammad-Hossein,Seo, Seong-Hyun,Oh, Hee-Mock Elsevier Applied Science 2017 Bioresource technology Vol.244 No.1
<P><B>Abstract</B></P> <P>The effects of phosphorus concentration on the cell growth, nutrient assimilation, photosynthetic parameters, and biomass recovery of <I>Ettlia</I> sp. were evaluated with batch experiments using groundwater, 50mg/L of N-NO<SUB>3</SUB> <SUP>−</SUP>, and different concentrations of P-PO<SUB>4</SUB> <SUP>3−</SUP>: 0.5, 2.5, 5, and 10mg/L. The maximum biomass productivity and phosphorus removal rate were 0.2g/L/d and 5.95mg/L/d, respectively, with the highest phosphorus concentration of 10mg/L. However, a phosphorus concentration of 5mg/L (N:P=10) was sufficient to ensure an effective nitrogen removal rate of 11mg/L/d, maximum growth rate of 0.88/d, and biomass recovery of 0.72. The appropriate hydraulic retention time was considered as 4days on a large scale to meet the effluent limitation demands of water. While nitrogen depletion had a significant effect on the photosynthetic parameters and ratio of chlorophyll <I>a</I> to dry cell weight during the stationary phase, the effect of phosphorus was negligible during the cultivation.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Applying <I>Ettlia</I> sp. for biomass production and nitrate removal from groundwater. </LI> <LI> Using batch glass columns with a surface area of 7.9×10<SUP>−3</SUP> m<SUP>2</SUP> and a working volume of 1.7×10<SUP>−3</SUP> m<SUP>3</SUP>. </LI> <LI> 5mg/L of P (N:P=10) was sufficient to ensure an effective N removal rate of 11mg/L/d. </LI> <LI> A hydraulic retention time of 4days was considered for a large scale application. </LI> <LI> Biomass recovery of <I>Ettlia</I> sp. by easy auto-flocculation reached up to 0.72. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Dynamic response of railway bridges traversed simultaneously by opposing moving trains
Rezvani, Mohammad Ali,Vesali, Farzad,Eghbali, Atefeh Techno-Press 2013 Structural Engineering and Mechanics, An Int'l Jou Vol.46 No.5
Bridges are vital components of the railroads. High speed of travel, the periodic and oscillatory nature of the loads and the comparable vehicle bridge weight ratio distinguish the railway bridges from the road bridges. The close proximity between estimations by some numerical methods and the measured data for the bridge-vehicle dynamic response under the moving load conditions has boosted the confidence in the numerical analyses. However, there is hardly any report regarding the responses of the railway bridges under the effect of the trains entering from the opposite directions while running at unequal speed and having dissimilar geometries. It is the purpose of this article to present an analytical method for the dynamic analysis of the railway bridges under the influence of two opposing series of moving loads. The bridge structural damping and many modes of vibrations are included. The concept of modal superposition is used to solve for the system motion equations. The method of solution is indeed a computer assisted analytical solution. It solves for the system motion equations and gives output in terms of the bridge deflection. Some case studies are also considered for the validation of the proposed method. Furthermore, the effects of varying some parameters such as the distance between the bogies, and the bogie wheelset distance are studied. Also, the conditions of resonance and cancellation in the dynamic response for a variety of vehicle-bridge specifications are investigated.
RANKING EXPONENTIAL TRAPEZOIDAL FUZZY NUMBERS WITH CARDINALITY
Rezvani, Salim Korean Mathematical Society 2014 대한수학회논문집 Vol.29 No.1
In this paper, we want to represent a method for ranking of two exponential trapezoidal fuzzy numbers. In this study a new Cardinality between exponential trapezoidal fuzzy numbers is proposed. Cardinality in this method is relatively simple and easier in computation and ranks various types of exponential fuzzy numbers. For the validation the results of the proposed approach are compared with different existing approaches.
Majid Rezvani,Reza Abbasi,Homayoon Tabesh,Leila Dehghani,Shahaboddin Dolatkhah,Maryam Nasri,Mohsen Kolahdouzan,Rokhsareh Meamar 대한척추외과학회 2018 Asian Spine Journal Vol.12 No.3
Study Design: Randomized clinical trial. Purpose: In this study, we evaluated the effect of mechanical evacuation of the bowels prior to operation on intraoperative bleeding. Overview of Literature: Bleeding is the most significant complication in patients undergoing spinal surgery. Methods: We randomly divided 108 individuals planned to undergo spinal surgery into two age-, sex-, and co-morbidity (especially preoperative hemoglobin [Hb])-matched groups of 54. The treatment group was administered polyethylene glycol (PEG) before the operation, whereas the control group was not. The exact amount (mL) of bleeding during operation, operative time, and approximate amount of blood transfused were recorded. The volume of bleeding and Hb level were also recorded 24 and 48 hours postoperatively. Results: T -tests revealed that intraoperative bleeding, the volume of transfusion, and operative time were significantly lower in the treatment group than in the control group. Statistically significant correlations of intraoperative bleeding with age, body mass index (BMI), preoperative Hb levels, operative time, the volume of transfusion, hospitalization time, and 24- and 48-hour postoperative bleeding were observed (p =0.001, all). Repeated measures analysis of covariance after adjusting the covariate variables revealed that the volume of bleeding showed a near-significant trend in the treatment group compared with that in the control group (p =0.056). Diabetic females had the highest bleeding amount between the groups (p =0.03). Bleeding was higher in patients with higher BMI (p =0.02) and was related to operative time (p =0.001) in both the groups. Conclusions: Preoperative gastrointestinal tract evacuation by PEG administration can decrease intraoperative bleeding in spinal surgeries; however, more research is imperative regarding PEG administration in surgical procedures for this purpose.
A Novel WBAN MAC protocol with Improved Energy Consumption and Data Rate
( Sanaz Rezvani ),( S. Ali Ghorashi ) 한국인터넷정보학회 2012 KSII Transactions on Internet and Information Syst Vol.6 No.9
Wireless Body Area Networks (WBANs) are introduced as an enabling technology in tele-health for patient monitoring. Designing an efficient Medium Access Control (MAC) protocol is the main challenge in WBANs because of their various applications and strict requirements such as low level of energy consumption, low transmission delay, the wide range of data rates and prioritizing emergency data. In this paper, we propose a new MAC protocol to provide different requirements of WBANs targeted for medical applications. The proposed MAC provides an efficient emergency response mechanism by considering the correlation between medical signals. It also reduces the power consumption of nodes by minimizing contention access, reducing the probability of the collision and using an efficient synchronization algorithm. In addition, the proposed MAC protocol increases the data rate of the nodes by allocating the resources according to the condition of the network. Analytical and simulation results show that the proposed MAC protocol outperforms IEEE 802.15.4 MAC protocol in terms of power consumption level as well as the average response delay. Also, the comparison results of the proposed MAC with IEEE 802.15.6 MAC protocol show a tradeoff between average response delay and medical data rate.
Vibration of a Circular plate on Pasternak foundation with variable modulus due to moving mass
Mohsen Rezvani Alile,Mohammad Ali Foyouzat,Massood Mofid 국제구조공학회 2022 Structural Engineering and Mechanics, An Int'l Jou Vol.83 No.6
In this paper, the vibration of a moderately thick plate to a moving mass is investigated. Pasternak foundation with a variable subgrade modulus is considered to tackle the shortcomings of Winkler model, and an analytical-numerical solution is proposed based on the eigenfunction expansion method. Parametric studies by using both CPT (Classical Plate Theory) and FSDT (First-Order Shear Deformation Plate Theory) are carried out, and, the differences between them are also highlighted. The obtained results reveal that utilizing FSDT without considering the rotary inertia leads to a smaller deflection in comparison with CPT pertaining to a thin plate, while it demonstrates a greater response for plates of higher thicknesses. Moreover, it is shown that CPT is unable to properly capture the variation of the plate thickness, thereby diminishing the accuracy as the thickness increases. The outcomes also indicate that the presence of a foundation contributes more to the dynamic response of thin plates in comparison to moderately thick plates. Furthermore, the findings suggest that the performance of the moving force approach for a moderately thick plate, in contrast to a thin plate, appears to be acceptable and it even provides a much better estimation in the presence of a foundation.
Majid Rezvani,Jamalodin Asadi,Arman Sourani,Mina Foroughi,Donya Sheibani Tehrani 대한신경손상학회 2023 Korean Journal of Neurotrauma Vol.19 No.1
To investigate the efficacy and safety of two different techniques for spinal ligamentotaxis. Spine ligamentotaxis reduces the number of retropulsed bone fragments in the fractured vertebrae. Two different ligamentotaxis techniques require clinical evaluation.