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Pore-scale simulation of calcite matrix acidizing with hydrochloric acid
, Article SPE Journal ; Volume 26, Issue 2 , 2021 , Pages 653-666 ; 1086055X (ISSN) ; Sharif University of Technology
Society of Petroleum Engineers (SPE)
2021
Abstract
A continuum hydrodynamic model with immersed solid/fluid interface is developed for simulating calcite dissolution by hydrochloric acid (HCl) at the pore scale, and is most accurate for a mass-transfer-controlled dissolution regime under laminar flow conditions. The model uses averaged Navier-Stokes equations to model momentum transfer in porous media and adopts a theoretically developed mass-transfer formulation with assumptions. The model includes no fitting parameter and is validated using experimental results. The findings of previous research and existing models are briefly discussed and their shortcomings and advantages are elucidated. The present model is used in some pore-scale...
Bus maintenance systems and maintenance scheduling: Model formulations and solutions
, Article Transportation Research Part A: Policy and Practice ; Volume 36, Issue 5 , 2002 , Pages 453-482 ; 09658564 (ISSN) ; Shafahi, Y ; Sharif University of Technology
Elsevier Ltd
2002
Abstract
This paper deals with the problem of scheduling bus maintenance activities. The scheduling of maintenance activities is an important component in bus transit operations planning process. The other components include network route design, setting timetables, scheduling vehicles, and assignment of drivers. This paper presents a mathematical programming approach to the problem. This approach takes as input a given daily operating schedule for all buses assigned to a depot along with available maintenance resources. It, then, attempts to design daily inspection and maintenance schedules for the buses that are due for inspection so as to minimize the interruptions in the daily bus operating...
Does the short-term boost of renewable energies guarantee their stable long-term growth? Assessment of the dynamics of feed-in tariff policy
, Article Renewable Energy ; Volume 159 , October , 2020 , Pages 1252-1268 ; Hamed Shakouri, G ; Mashayekhi, A. N ; Kazemi, A ; Sharif University of Technology
Elsevier Ltd
2020
Abstract
Feed-in tariff (FiT) is one of the most efficient ways that many governments throughout the world use to stimulate investment in renewable energies (REs) technology. For governments, financial management of the policy could be challenging as it needs a considerable amount of budget to support RE producers during the long remuneration period. In this paper, it has been illuminated that the early growth of REs capacity could be a temporary boost. And the socio-economic structure of the system will backlash the policy if some social mechanisms are not considered. Social tolerance for paying REs tax and potential investors’ trust emanated from budget-related mechanisms -which have rarely been...
Stochastic Traffic Assignment Based on Discrete Choice Models
, M.Sc. Thesis Sharif University of Technology ; Zakaei Ashtiani, Hedayat (Supervisor)
Abstract
Accurate and realistic forecasts of traffic pattern in the networks can affect many decisions of urban transportation planning. In recent years, traffic assignment (TA) using stochastic models have received more attention by researchers of this field. Stochastic approach of route choice modeling using random utility theory has specifically developed to relax restrictive assumptions of traditional deterministic model and to address randomness nature of travelerʼs behavior. Together with development of discrete choice theory, more advanced models have been utilized to better represent route choice behavior. Although there have been considerable researches in the context of stochastic traffic...
Bus network design using genetic algorithm
, Article 53rd Annual Transportation Research Forum, TRF 2012, 15 March 2012 through 17 March 2012, Tampa, FL ; Volume 1 , 2012 , Pages 210-225 ; 9781622764037 (ISBN) ; Poorzahedi, H ; Haghani, A ; Sharifi, E ; Sharif University of Technology
2012
Abstract
The bus network design problem is an important problem in transportation planning. It is the problem of determining a network of bus lines which best achieves a predetermined objective. This may be done with or without the presence of rapid transit lines. This study is devoted to solving this problem using genetic algorithm. The fitness function is defined as the benefit to the users of the bus network less the cost of the operator of the network, which is to be maximized subject to constraints that properly distribute bus routes over the study area. Objective function calculation depends on the basic data of the city and its bus lines and does not need traffic assignment results. So, it is...
Endurance time analysis of skewed slab-on-girder bridges: the significance of the excitation angle
, Article Scientia Iranica ; Volume 26, Issue 4A , 2019 , Pages 2276-2285 ; 10263098 (ISSN) ; Ghaffari, E ; Haghani Baei, A ; Sharif University of Technology
Sharif University of Technology
2019
Abstract
In this paper, the influence of the excitation angle on the Endurance Time (TCT) analysis of skewed slab-on-girdcr bridges is studied. The excitation of the structure due to the critical angle produces maximum seismic responses that are sometimes significantly higher than the average. The modeled bridges are of slab-on-girder type that are typically used as highway bridges. The bridge models have skew angles of 0, 15, 30, 45, and CO degrees. The ET excitations exerted on structures cover a broad range of hazard levels. The results provide some insight with regard to choosing multiple excitation angles so as to balance computational costs and retain acceptable accuracy for practical design...
Endurance time analysis of skewed slab-on-girder bridges: The significance of the excitation angle
, Article Scientia Iranica ; Volume 26, Issue 4A , 2019 , Pages 2276-2285 ; 10263098 (ISSN) ; Ghaffari, E ; Haghani Baei, A ; Sharif University of Technology
Sharif University of Technology
2019
Abstract
In this paper, the influence of the excitation angle on the Endurance Time (TCT) analysis of skewed slab-on-girdcr bridges is studied. The excitation of the structure due to the critical angle produces maximum seismic responses that are sometimes significantly higher than the average. The modeled bridges are of slab-on-girder type that are typically used as highway bridges. The bridge models have skew angles of 0, 15, 30, 45, and CO degrees. The ET excitations exerted on structures cover a broad range of hazard levels. The results provide some insight with regard to choosing multiple excitation angles so as to balance computational costs and retain acceptable accuracy for practical design...
Lower-bound solution algorithm for equilibrium signal-setting problem
, Article Transportation Research Record ; Issue 2085 , 2008 , Pages 104-110 ; 03611981 (ISSN) ; Zokaei Aashtiani, H ; Haghani, A ; Sharif University of Technology
2008
Abstract
The equilibrium signal-setting problem is stated and subsequently formulated as a continuous equilibrium network design problem. The bilevel formulation is nonconvex and therefore cannot be solved for global optima by using descent solution algorithms. Therefore, a lower bound using a system optimal flow pattern is proposed that will be quite tight in both uncongested and highly congested network traffic situations. A solution algorithm based on the standard steepest-descent method is proposed for the lower-bound problem. Performance of the solution algorithm on a network problem is reported
Seismic Performance and Cost Assessment of Concrete Bridges Designed by Iranian Bridge Code
, M.Sc. Thesis Sharif University of Technology ; Esmaeil Purestekanchi, Homayoun (Supervisor)
Abstract
The purpose of this study is to evaluate the performance and seismic costs for pre-designed bridges according to the Iranian Bridge Code, which maps and details are available in Code 294. In order to evaluate performance, seismic costs of a structures are determined over its life cycle and these costs are compared eventually. Seismic costs are divided into two parts of the initial cost and life cycle cost of the structure. The initial costs depend on the cost of constructing the bridge, but life cycle costs are depends on seismic damage for structure and its users over the useful life of the bridge. These damages include the cost of maintenance of the bridge over its useful life and the...
Dynamic comparison of segmentary scapulohumeral rhythm between athletes with and without impingement syndrome
, Article Iranian Journal of Radiology ; Vol. 11, issue. 2 , 2014 ; Maroufi, N ; Ebrahimi Takamjani, I ; Farahmand, F ; Shakourirad, A ; Haghani, H ; Sharif University of Technology
2014
Abstract
Background: Patients who have shoulder pain usually have compensatory or contributory deviation of shoulder motion during arm elevation. In the traditional scapulohumeral rhythm, the share of the acromioclavicular (AC) and the sternoclavicular (SC) joint movements and also the role of AC internal rotation angle are unknown. Objectives: The main purpose of this study was to measure and compare the segmentary scapulohumeral rhythm (SSHR) during scapular arm elevation at a steady rotational speed in athletes with and without impingement syndrome. Patients and Methods: Using a speedometer, the maximum speed of arm elevation was measured in 21 men in each of the involved and uninvolved groups....
Reliability Evaluation of Heat Recovery Steam Generator of Combined Cycle Thermal Power Plants
, M.Sc. Thesis Sharif University of Technology ; Saeedi, Mohammad Hassan (Supervisor) ; Kazemzadeh Hannani, Siamak (Supervisor)
Abstract
Combined cycle power plants consist of three main sections, namely gas turbine, Heat Recovery Steam Generator (HRSG) and steam turbine. Occurring failure in HRSG causes the steam turbine trip, so the reliability assessment of HRSG has a great importance for forecasting the probability of occurring failure and also reducing failure causes. In this project, the reliability of HRSG considering effects of aging phenomenon, maintenance and, environmental and operational conditions on reliability is modeled. Afterward a method to estimate the model parameters is introduced. Using present method, failure data of six HRSGs of a plant each with a capacity of 50 MW is analyzed and the model parameters...
Statistical evaluation of using the new generation of wind turbines in South Africa
, Article Energy Reports ; Volume 6 , November , 2020 , Pages 2816-2827 ; Jahangiri, M ; Haghani, A ; Hosseini Dehshiri, S. J ; Hosseini Dehshiri, S. S ; Sedaghat, A ; Saghaei, H ; Akinlabi, E. T ; Sichilalu, S. M ; Chowdhury, S ; Techato, K ; Issakhov, A
Elsevier Ltd
2020
Abstract
In the view of the latest status and the potential of developing wind energy in South Africa, the present study aims to perform technical–economic–environmental analysis on a wind turbine system with HOMER software using the 20-years average data of the wind speed obtained from NASA's database, for providing the electricity to residential buildings. The results showed that the Port Elizabeth station, had the lowest levelized cost of electricity (LCOE) with the value of -0.363 $/kWh when using the EOLO wind turbine, and the Bloemfontein station had the highest LCOE with the value of 1.601 $/kWh when using the Turby wind turbine. The results from the step-wise assessment ratio analysis...
Smart micro/nanoparticles in stimulus-responsive drug/gene delivery systems
, Article Chemical Society Reviews ; Volume 45, Issue 5 , 2016 , Pages 1457-1501 ; 03060012 (ISSN) ; Ghasemi, A ; Sahandi Zangabad, P ; Rahighi, R ; Moosavi Basri, S. M ; Mirshekari, H ; Amiri, M ; Shafaei Pishabad, Z ; Aslani, A ; Bozorgomid, M ; Ghosh, D ; Beyzavi, A ; Vaseghi, A ; Aref, A. R ; Haghani, L ; Bahrami, S ; Hamblin, M. R ; Sharif University of Technology
Royal Society of Chemistry
2016
Abstract
New achievements in the realm of nanoscience and innovative techniques of nanomedicine have moved micro/nanoparticles (MNPs) to the point of becoming actually useful for practical applications in the near future. Various differences between the extracellular and intracellular environments of cancerous and normal cells and the particular characteristics of tumors such as physicochemical properties, neovasculature, elasticity, surface electrical charge, and pH have motivated the design and fabrication of inventive "smart" MNPs for stimulus-responsive controlled drug release. These novel MNPs can be tailored to be responsive to pH variations, redox potential, enzymatic activation, thermal...