Simulation of the behaviour of RC columns strengthen with CFRP under rapid loading

Esfandiari, Soheil,Esfandiari, Javad Techno-Press 2016 Advances in concrete construction Vol.4 No.4

In most cases strengthening reinforced concrete columns exposed to high strain rate is to be expected especially within weak designed structures. A special type of loading is instantaneous loading. Rapid loading can be observed in structural columns exposed to axial loads (e.g., caused by the weight of the upper floors during a vertical earthquake and loads caused by damage and collapse of upper floors and pillars of bridges).Subsequently, this study examines the behavior of reinforced concrete columns under rapid loading so as to understand patterns of failure mechanism, failure capacity and strain rate using finite element code. And examines the behavior of reinforced concrete columns at different support conditions and various loading rate, where the concrete columns were reinforced using various counts of FRP (Fiber Reinforcement Polymer) layers with different lengths. The results were compared against other experimental outcomes and the CEB-FIP formula code for considering the dynamic strength increasing factor for concrete materials. This study reveals that the finite element behavior and failure mode, where the results show that the bearing capacity increased with increasing the loading rate. CFRP layers increased the bearing capacity by 20% and also increased the strain capacity by 50% through confining the concrete.

Experimental and numerical investigation on RC moment-Resisting frames retrofitted with NSD yielding dampers

Esfandiari, J.,Zangeneh, E.,Esfandiari, S. Techno-Press 2022 Advances in concrete construction Vol.13 No.4

Retrofitting in reinforced concrete structures has been one of the most important research topics in recent years. There are several methods for retrofitting RC moment-resisting frames. the most important of which is the use of steel bracing systems with yielding dampers. With a proper design of yielding dampers, the stiffness of RC frame systems can be increased to the required extent so that the ductility of the structure is not significantly reduced. In the present study, two experimental samples of a one-third scale RC moment-resisting frame were loaded in the laboratory. In these experiments, the retrofitting effect of RC frames was investigated using Non-uniform Slit Dampers (NSDs). Based on the experimental results of the samples, seismic parameters, i.e., stiffness, ductility, ultimate strength, strength reduction coefficient, and energy dissipation capacity, were compared. The results demonstrated that the retrofitted frame had very significant growth in terms of stiffness, ultimate strength, and energy dissipation capacity. Although the strength reduction factor and ductility decreased in the retrofitted sample. In general, the behavior of the frame with NSDs was evaluated better than the bare frame.

How the New York Times Portrayed the 2010 Brazil-Turkey-Iran Nuclear Deal: A Critical Discourse Analysis

Esfandiary, Esmaeil World Association for Triple Helix and Future Stra 2015 Journal of Contemporary Eastern Asia Vol.14 No.2

This paper examines the New York Times' reaction to the 2010 Brazil-Turkey-Iran (BTI) nuclear deal, the very last diplomatic effort before the imposition of international sanctions track over the following years. The New York Times' (NYT) coverage of the deal is examined using the Critical Discourse Analytic (CDA) approach formulated by Teun van Dijk. The results show a strong bias against the BTI deal throughout the NYT's news coverage. The overarching theme in cover-age of the deal is the imputation of malignant intentions on the part of both Iran ("to kill time to further its nuclear weapons program") and Brazil and Turkey ("to advance their own business dealings with Iran and gaining international recognition"). Also, non-relevant information is used to imply a threat of Iranian development of nuclear weapons. Moreover, the NYT leaves almost totally "unsaid" that president Obama had asked Brazilian and Turkish leaders to go to Tehran and get this deal. Therefore, the NYT basically echoed, and legitimized, discursive practices of the U.S. government on the deal.

A structural model updating method using incomplete power spectral density function and modal data

Esfandiari, Akbar,Chaei, Maryam Ghareh,Rofooei, Fayaz R. Techno-Press 2018 Structural Engineering and Mechanics, An Int'l Jou Vol.68 No.1

In this study, a frequency domain model updating method is presented using power spectral density (PSD) data. It uses the sensitivity of PSD function with respect to the unknown structural parameters through a decomposed form of transfer function. The stiffness parameters are captured with high accuracy through solving the sensitivity equations utilizing the least square approach. Using numerically noise polluted data, the model updating results of a truss model prove robustness of the method against measurement and mass modelling errors. Results prove the capabilities of the method for parameter estimation using highly noise polluted data of low ranges of excitation frequency.

Numerical study of progressive collapse in reinforced concrete frames with FRP under column removal

Esfandiari, J.,Latifi, M.K. Techno-Press 2019 Advances in concrete construction Vol.8 No.3

Progressive collapse is one of the factors which if not predicted at the time of structure plan; its occurrence will lead to catastrophic damages. Through having a glance over important structures chronicles in the world, we will notice that the reason of their collapse is a minor damage in structure caused by an accident like a terrorist attack, smashing a vehicle, fire, gas explosion, construction flaws and its expanding. Progressive collapse includes expanding rudimentary rupture from one part to another which leads to total collapse of a structure or a major part it. This study examines the progressive collapse of a 5-story concrete building with three column eliminating scenarios, including the removal of the corner, side and middle columns with the ABAQUS software. Then the beams and the bottom of the concrete slab were reinforced by (reinforcement of carbon fiber reinforced polymer) FRP and then the structure was re-analyzed. The results of the analysis show that the reinforcement of carbon fiber reinforced polymer sheets is one of the effective ways to rehabilitate and reduce the progressive collapse in concrete structures.

Cross-Cultural Adaptation and Validation of the Persian Version of the 24-Item Early-Onset Scoliosis Questionnaire

Esfandiari Mahmood,Babaee Taher,Kamyab Mojtaba,Kamali Mohammad,Matsumoto Hiroko,Ghandhari Hassan,Vitale Michael G. 대한척추외과학회 2022 Asian Spine Journal Vol.16 No.1

Study Design: Cross-sectional study.Purpose: To translate and culturally adapt the original English version of the 24-item Early-Onset Scoliosis Questionnaire (EOSQ-24) to the Persian language as well as assess its reliability and validity.Overview of Literature: Early-onset scoliosis (EOS) patients with progressive curves require active treatments, such as serial elongation– derotation–flexion casting, bracing, and surgery, which are stressful and expensive. In order to evaluate the impact of EOS and its treatment strategies, it is important to consider the patients and their parents’ quality of life as the clinical and radiological parameters. The EOSQ-24 is a parent-based measure that evaluates the health-related quality of life of patients with EOS and their caregivers/parents. Similar to other widely used questionnaires, EOSQ-24 needs to be translated into other languages to make it usable in populations from different cultures and societies.Methods: We evaluated the translation and back translation of the EOSQ-24 and made the required revisions as per the analysis performed by the expert committee and an international guideline to adapt it for use in this study. Thereafter, we recruited 100 EOS patients in order to evaluate its reliability and validity. The reliability was assessed with internal consistency. Convergent validity was assessed by comparing the scores of the EOSQ-24 and the 22-item Scoliosis Research Society Questionnaire (SRS-22r). Finally, the known groups validity was assessed as per patient’s sex, curve magnitude, and treatment type.Results: The Persian EOSQ-24 demonstrated very good internal consistency (Cronbach’s α=0.88). All the items had an acceptable corrected item-total correlation (>0.3). Further, the EOSQ-24 and the SRS-22r scores (p <0.001) were significantly correlated. The EOSQ-24 could discriminate patients with different curve magnitudes.Conclusions: The Persian EOSQ-24 can serve as a disease-specific instrument with strong validity and reliability in the evaluation of EOS patients. Its applicability in other Persian-speaking countries and regions of the world needs to be investigated further.

Power Quality Impacts of an Electric Arc Furnace and Its Compensation

Esfandiari Ahmad,Parniani Mostafa,Mokhtari Hossein The Korean Institute of Electrical Engineers 2006 Journal of Electrical Engineering & Technology Vol.1 No.2

This paper presents a new compensating system, which consists of a shunt active filter and passive components for mitigating voltage and current disturbances arising from an Electric Arc Furnace (EAF). A novel control strategy is presented for the shunt active filter. An extended method based on instantaneous power theory in a rotating reference frame is developed for extraction of compensating signals. Since voltages at the point of common coupling contain low frequency interharmonics, conventional methods cannot be used for dc voltage regulation. Therefore, a new method is introduced for this purpose. The passive components limit the fast variations of load currents and mitigate voltage notching at the Point of Common Coupling (PCC). A three-phase electric arc furnace model is used to show power quality improvement through reactive power and harmonic compensation by a shunt active filter using the proposed control method. The system performance is investigated by simulation, which shows improvement in power quality indices such as flicker severity index.

Dynamic Optimization of Capital Stock: An Application of Maximum Principle

Marziyeh Esfandiari 대한산업공학회 2020 Industrial Engineeering & Management Systems Vol.19 No.3

Determining the optimized level of economic variables is very influential in compiling economic plans and policies. This study deals with the determination of the country’s optimized capital stock by the use of Pontryagin’s Maximum Principle in the time period 1972-2017. The product function is assumed as Cobb-Douglas, and the coefficients of product function are measured by Eviews software. After that, the achieved differential equation applying from Maximum Principle is solved by the use of numerical methods via MATLAB software. Then, under certain hypotheses about the rate of depreciation and the ratio of savings, the optimized capital stock is calculated and is compared to the real ones. Findings of the study approve that there are big gaps between the existing situation and the optimized capital stock in Iran. In order to decrease the gap, it is urgent to increase investment and take policies for provoking the private sectors.

Power Quality Improvement of an Electric Arc Furnace Using a New Universal Compensating System

Ahmad Esfandiari,Mostafa Parniani,Hossein Mokhtari,Ali Yazdian-Varjani 전력전자학회 2006 JOURNAL OF POWER ELECTRONICS Vol.6 No.3

This paper presents a new compensating system, consisting of series and shunt active filters, for mitigating voltage and current disturbances. The shunt filter is used to compensate for unbalanced and distorted load currents. The series filter comprises two inverters, used to suppress voltage disturbances and handle source currents independently. This configuration is devised to reduce the overall cost of active compensators by using low-frequency high-current switches for the latter inverter. The filters are controlled separately using a novel control strategy. Since voltages at the point of common coupling contain interharmonics, conventional methods cannot be used for extracting voltage references. Therefore, voltage references are obtained from generated sinusoidal waveforms by a phase-locked loop. Current references are detected based on rotating frame vector mapping. Simulation results are presented to verify the system.

An epidemiological comparative study on diagnosis of rodent leptospirosis in Mazandaran Province, northern Iran

Behzad Esfandiari,Mohammad Reza Pourshafie,Mohammad Mehdi Gouya,Pejvak Khaki,Ehsan Mostafavi,Jamshid Darvish,Soheila Moradi Bidhendi,Hamed Hanifi,Hossein Nahrevanian 한국역학회 2015 Epidemiology and Health Vol.37 No.-

OBJECTIVES: Leptospirosis is a zoonosis caused by leptospires, in which transmission occurs through contact with contaminated biological fluids from infected animals. Rodents can act as a source of infection for humans and animals. The disease has a global distribution, mainly in humid, tropical and sub-tropical regions. The aim of this study was to compare culture assays, the microscopic agglutination test (MAT), polymerase chain reac-tion (PCR), and nested PCR (n-PCR), for the diagnosis of leptospirosis in rodents in Mazandaran Province, northern Iran. METHODS: One hundred fifty-one rodents were trapped alive at 10 locations, and their urine and kidney samples were collected and used for the isolation of live Leptospira. The infecting serovars were identified and the antibody titres were measured by MAT, using a panel of 20 strains of live Leptospira species as antigens. The presence of leptospiral DNA was evaluated in urine and kidney samples using PCR and n-PCR. RESULTS: No live leptospires were isolated from the kidney and urine samples of the rodents. Different de-tection rates of leptospirosis were observed with MAT (21.2%), PCR (11.3%), and n-PCR (3.3%). The domi-nant strain was Leptospira serjoehardjo (34.4%, p= 0.28), although other serotypes were also found. The prev-alence of positive leptospirosis tests in rodents was 15.9, 2.6, and 2.6% among Rattus norvegicus, R. rattus, and Apodemus sylvaticus, respectively. CONCLUSIONS: Leptospirosis was prevalent in rodents in Mazandaran Province, northern Iran. MAT was able to detect leptospires more frequently than culture or PCR. The kidney was a more suitable site for identi-fying leptospiral DNA by n-PCR than urine. Culture was not found to be an appropriate technique for clinical diagnosis.