Saghafi M.,Bonab University |
Yousefpour F.,Nuclear Science and Technology Research Institute, Iran |
Karimi K.,Islamic Azad University at Tehran |
Hoseyni S.M.,Islamic Azad University at Tehran
International Journal of Hydrogen Energy | Year: 2017
This paper deals with determination of the minimum number and identification of the best configurations of passive autocatalytic recombiners (PAR) for the effective design of the containment in a pressurized water reactor (PWR). It considers the current design of PAR in the containment of a PWR and for that tries to identify, through a large number of sensitivity analyses, the minimum required number of PARs in different compartments. In this regard, a qualified nodalization has been developed for best estimate modeling by MELCOR integrated code. The developed model includes primary and secondary systems, containment, and related safety systems. A large number of simulations including the plant specific probabilistic safety assessment and success criteria analysis are used to identify the accident scenario with the highest amount of hydrogen production and risk. We first screened postulated accidents based on the PSA results and then based on the deterministic severe accident computations. It is found that the large break loss of coolant accident (LB-LOCA) without emergency core cooling system (ECCS) actuation is the bounding case from the hydrogen hazard point of view. To find the optimal configuration with minimum number of PARs in the containment, 40 different configurations are analyzed for the selected accident for a Westinghouse type PWR. The main finding of this work is identification of the minimum required number of PARs and their best distribution among the associated compartments. The obtained configuration is equally effective for the hydrogen risk mitigation with 36% reduction in the number of PARs in comparison to the base case design. The methodology of the analysis can be used for other plants. © 2017 Hydrogen Energy Publications LLC.
Sadighi-Bonabi R.,Sharif University of Technology |
Pasandideh K.,Sharif University of Technology |
Zand M.,Nuclear Science and Technology Research Institute, Iran |
Nazari Mahroo H.,Bonab University
Laser Physics | Year: 2017
Using an appropriate design of electrodes and adjustment of the thyratron decoupling circuit as a high-repetition-rate and high-voltage switch, very stable operation of a copper vapor laser at high pressures was obtained. This was achieved by canceling the intense filamentation in the laser plasma at the higher pressures. The transverse grooves on the inner surface of the funnel-shaped copper electrodes permit operation of the laser up to 100 torr. This design reduces the cathode-fall voltage, and as a result reduces the thermal loading in the cathode-fall region. The optimum pressure was 80 torr. At this condition the output power was more than that observed with expensive molybdenum electrodes in a similar laser system. © 2017 Astro Ltd.
PubMed | Bonab University, National University of Singapore and Amirkabir University of Technology
Type: | Journal: Carbohydrate polymers | Year: 2016
Nanofibrous nerve guides have gained huge interest in supporting the peripheral nerve regeneration due to their abilities to simulate the topography, mechanical, biological and extracellular matrix morphology of native tissue. Gum tragacanth (GT) is a biocompatible mixture of polysaccharides that has been used in biomedical applications. During this study, we fabricated aligned and random nanofibers from poly(l-lactic acid) and gum tragacanth (PLLA/GT) in various ratios (100:0, 75:25, and 50:50) by electrospinning. Scanning electron microscope demonstrated smooth and uniform nanofibers with diameters in the range of 73365nm and 22673nm for align PLLA and random PLLA/GT 50:50 nanofibers, respectively. FTIR analysis, contact angle, in vitro biodegradation and tensile measurements were carried out to evaluate the chemical and mechanical properties of the different scaffolds. PLLA/GT 75:25 exhibited the most balanced properties compared to other scaffolds and was used for in vitro culture of nerve cells (PC12) to assess the potential of using these scaffolds as a substrate for nerve regeneration. The cells were found to attach and proliferate on aligned PLLA/GT 75:25 scaffolds, expressing bi-polar neurite extensions and the orientation of nerve cells was along the direction of the fiber alignment. Results of 8 days of in vitro culture of PC12 cells on aligned PLLA/GT 75:25 nanofibers, showed 20% increase in cell proliferation compared to PLLA/GT 75:25 random nanofibers. PLLA/GT 75:25 aligned nanofibers acted as a favorable cue to support neurite outgrowth and nerve cell elongation compared with PLLA nanofibers. Our results showed that aligned PLLA/GT 75:25 nanofibers are promising substrates for application as bioengineered grafts for nerve tissue regeneration.
Fallah M.,Amirkabir University of Technology |
Bahrami S.H.,Amirkabir University of Technology |
Ranjbar-Mohammadi M.,Bonab University
Journal of Industrial Textiles | Year: 2016
Phytochemicals have been used over the centuries in order to cure various diseases and still do to this day. Phytochemicals are herbal extracts that are also named herbal remedies. Curcumin (CUR), which is a natural polyphenolic compound derived from the roots of the plant Curcuma Longa, has many therapeutic properties. CUR has poor water solubility and instability that has confined its further applications, thus there is need for a carrier to deliver the drug consistently. In this research, the feasibility of using polycaprolactone/gelatin nanofibers as carriers for CUR is examined. Nanofibers are obtained by electrospinning method. The morphology of nanofibers was observed by scanning electron microscopy. Fourier Transform Infrared Spectroscopy and differential scanning calorimetry is used to study the thermal behavior of the nanofibers. Antibacterial tests were conducted against methicillin-resistant staphylococcus aureus (MRSA) and extended spectrum β lactamase (ESBL). These pathogens are very dangerous and versatile pathogens emerging rapidly causing nosocomial infections in hospitals. The nanofibers were 99.9% antibacterial against MRSA and 82.56% against ESBL. The results showed that these nanofibers have potent antibacterial activity against both Gram positive and Gram negative bacteria. As a result, these nanofibers are very promising materials for antibacterial applications. © 2015, © The Author(s) 2015.
Mokhtari H.,Bu - Ali Sina University |
Esmaeili F.,University of Tabriz |
Dabbagh-Yarishah J.,Bonab University
Transactions of the Indian Institute of Metals | Year: 2016
In this study, the effects of electrode clamping force on the fatigue strength of 5083-0 aluminum alloy spot-welded joints have been investigated via experimental and multiaxial fatigue analysis. To do so, three sets of the specimens—with different amounts of the sheet spacing—which have been fabricated using different values of the electrode clamping force, were selected, and then fatigue tests were performed under various cyclic longitudinal load levels. A nonlinear finite element code was used to obtain the stress and strain distribution near the roots of the nuggets as a result of longitudinal applied loads. Fatigue lives of the specimens were estimated with Crossland, Kandil–Brown–Miller, Glinka, Varvani-Farahani, Fatemi–Socie, and Smith–Watson–Topper multiaxial fatigue criteria by means of the local stress and strain distribution obtained from the finite element analysis. It was shown that, the fatigue lives of spot-welded joints were improved by increasing the electrode clamping force. Also, the comparison between experimental results and multiaxial fatigue predictions revealed that among the applied criteria, the Crossland and Glinka approaches had the best accuracy for all types of the specimens. © 2016 The Indian Institute of Metals - IIM
Abbasbandy S.,Imam Khomeini International University |
Hashemi M.S.,Imam Khomeini International University |
Hashemi M.S.,Bonab University
Engineering Analysis with Boundary Elements | Year: 2011
In this paper, we consider the Cauchy problem for the Laplace equation by group preserving scheme (GPS) which is an ill-posed problem, because the solution does not depend continuously on the data. For this, the Laplace equation, by using a semi-discretization method namely method of line, is converted to an ODEs system and then obtained ODEs system is considered by GPS. Stability of GPS for ill-posed Laplace equation is shown. The problem numerical results show the efficiency and power of this method. © 2011 Elsevier Ltd. All rights reserved.
Rahimi F.,Bonab University |
Roberts A.C.,Northwestern University |
Jog M.,London Health Sciences Center
Clinical Neurology and Neurosurgery | Year: 2016
Objectives Freezing of gait (FoG) is a challenging clinical symptom in Parkinson's disease with variable improvements in FoG with rasagiline. In this prospective, uncontrolled, pre-/post- treatment pilot study, we explore the clinical variables that contribute to this variability and those that predict improvement. Patients and methods Frequency and duration of FoG, along with other standardized scales, were evaluated in 18 optimally medicated PD participants with intractable FoG, prior to and after completion of a 90-day course of 1 mg daily rasagiline. Gait tasks were video-recorded and analyzed by two independent reviewers. After evaluating the simple main effect, hierarchical cluster analysis was used to identify subgroups for treatment responsiveness. Bidirectional elimination stepwise regression analysis was conducted to identify which clinical variables predicted reduction in frequency of FoG events post-treatment. Results There were no overall pre-/post- treatment improvements, a result driven by a heterogeneous response to treatment. Three subgroups were identified: improved (n = 6) with a 136% and 162% reduction in FoG count and duration; worsened (n = 5) with 154% and 141% increase in FoG count and duration; and no change (n = 3). The final predictive model had good explanatory power (adjusted-R2 = 0.9898, p < 0.01), explaining 99% of the variance between the improved and worsened groups. In this model, lower UPDRS gait scores, higher LEDD dose, lower anxiety scores, lower FOG-Q scores, and higher UPDRS scores for lower extremity rigidity and rise from chair, predicted FoG-related rasagiline benefit. Conclusion Using both objective and subjective measures for FoG, the current pilot study identified a set of clinical variables that may elucidate the heterogeneous FoG-responsiveness following rasagiline treatment and aid in predicting improvement. © 2016 Elsevier B.V.
Majidabad S.S.,Bonab University |
Shandiz H.T.,Shahrood University of Technology |
Control Engineering and Applied Informatics | Year: 2015
This paper presents two novel fast converging robust controllers for Caputo derivative based fractional-order nonlinear systems. These fractional-order systems are high-relative-degree with model uncertainties and external disturbances. First, a new fractional-order model is derived from the original model based on block transformation strategy. Employing the block transformation technique makes the highrelative- degree systems versatile for sliding mode controllers design. In the second step, two different nonlinear sliding manifolds are proposed to reach a short time convergence. Subsequently, appropriate nonlinear sliding mode control laws are developed to assure the robustness and fast converging behaviors. It is worthy to notify that the mentioned sliding manifolds guarantee the fractional-order system last state convergence, and the other states convergence can be assured by control gains of the block transformation. The stability of closed-loop system for both controllers is achieved by the fractionalorder stability theorems. Finally, two comprehensive numerical simulations are carried out to indicate the superiority and effectiveness of the suggested robust controllers.
Delghavi M.B.,Bonab University |
Shoja-Majidabad S.,Bonab University |
Yazdani A.,Ryerson University
IEEE Transactions on Sustainable Energy | Year: 2016
This paper proposes a voltage control strategy for islanded operation of dispatchable electronically coupled distributed energy resource (DER) systems, for remote (off grid) electrification systems. The proposed control strategy is based on fractional-order sliding-mode control, offers black-start functionality, maintains the quality of the output voltage of the host DER system in spite of unbalanced and/or distorted load currents, and ensures protection of the power-electronic interface to external faults. Moreover, the fractional derivative order of the controller can be used as an additional tuning parameter. Performance of the proposed control strategy is demonstrated through time-domain simulation of single-and multi-DER islanded networks, starting from black-start and subjected to various operating scenario, and it is also compared to the performance of a proportional-integral (PI)-based control strategy. © 2016 IEEE.
Irani G.N.H.,Bonab University |
Tawosi V.,Bonab University
2011 5th International Conference on Application of Information and Communication Technologies, AICT 2011 | Year: 2011
All Information Systems (IS) need an Authentication and Authorization (AA) System for security of their different modules. Existing Enterprise Systems, Frameworks and Portals use a similar centralized approach. In this paper, a new decentralized architecture has provided for AA in Modular Information Systems. To obtain this aim, firstly, all existing approaches and their disadvantages for AA, has been investigated and categorized. Secondly, to obtain a new architecture and solving disadvantages, new AA principles has been developed using robust object oriented principles and heuristics. New architecture has been developed based on these obtained AA principles. In addition, the new architecture decreases the Core complexity and distributes that into modules. Also the new architecture has maximum quality of reusability and extensibility and modifiability that can be applied to all Modular Information Systems. © 2011 IEEE.