The capture time of grids

, Article Discrete Mathematics ; Volume 311, Issue 1 , January , 2011 , Pages 102-105 ; 0012365X (ISSN) Mehrabian, A ; Sharif University of Technology

2011

Abstract

We consider the game of cops and robber played on the Cartesian product of two trees. Assuming the players play perfectly, it is shown that if there are two cops in the game, then the length of the game (known as the 2-capture time of the graph) is equal to half the diameter of the graph. In particular, the 2-capture time of the m×n grid is proved to be ⌊m+n2⌋-1

A new multi-sample EOS model for the gas condensate phase behavior analysis

, Article Oil and Gas Science and Technology ; Volume 66, Issue 6 , September , 2011 , Pages 1025-1033 ; 12944475 (ISSN) Mehrabian, A ; Crespo, F ; Sharif University of Technology

2011

Abstract

Equations of State EOS are vastly being used to predict the phase behavior of reservoir fluids. The accuracy of EOS modeling technique over conventional correlation models would benefit an improved property prediction of these fluids. Once the crude oil or gas condensate fluid system has been probably characterized using limited laboratory tests, its PVT behavior under a variety of conditions can be easily studied. In this paper, the PVT behavior of gas condensate from a reservoir in South Pars retrograde gas field in Iran was modeled using the three-parameter Patel and Teja Equation of State. The multi-sample characterization method is used to arrive at one consistent model for retrograde...

Effect of actuation frequency on the performance of diffuser micropumps

, Article 4th International Conference on Nanochannels, Microchannels and Minichannels, ICNMM2006, Limerick, 19 June 2006 through 21 June 2006 ; Volume 2006 B , 2006 , Pages 725-731 ; 0791847608 (ISBN); 9780791847602 (ISBN) Mehrabian, A ; Ahmadian, M. T ; Sharif University of Technology

2006

Abstract

Valveless piezoelectric micropumps are in wide practical use due to their ability to conduct particles with absence of interior moving mechanical parts. The objective of this paper is to obtain the fluid flow response to actuation frequency of a passive diffuser valve under harmonic pressures. In this regards a 2D model of a micropump valves and chambers is analyzed. The analysis is performed for 10Kpa back pressure on micropump chamber and actuation frequencies within the range of 1 Hz to 10 KHz. Results show the highest velocity in the direction of diffuser axis occurs at the narrow diffuser neck while flow direction reverses every half period. For low frequencies, a parabolic velocity...

TiO2 and C60 transport nanolayers in optimized Pb-free CH3NH3SnI3-based perovskite solar cells

, Article Materials Science and Engineering: B ; Volume 287 , 2023 ; 09215107 (ISSN) Mehrabian, M ; Afshar, E.N ; Akhavan, O ; Sharif University of Technology

Elsevier Ltd 2023

Abstract

A Pb-free perovskite solar cell has been designed based on methylammonium (MA) tin-iodide (CH3NH3SnI3). The effect of electron transporting layer (ETL) material on the performance of the solar cell has been studied through substituting the ETL by TiO2 and C60 nanolayers. The energy level and charge carrier concentration profiles of the solar cells have been obtained for better understanding the involved mechanisms. The TiO2-containing solar cell showed the maximum power conversion efficiency (η) of ∼25.5 % at room temperature, with open circuit voltage, short circuit current density and filling factor of ∼1.06 V, 33.0 mA/cm2 and 73.1 %, respectively. Although the C60-containing perovskite...

Study of Current Unbalance Propagation Pattern and HV Systems Share of Downstream Networks

, M.Sc. Thesis Sharif University of Technology Mehrabian, Mohammad Amin (Author) ; Mokhtari, Hossein (Supervisor)

Abstract

Electrical systems are prone to voltage or current unbalance due to unbalance loads or asymmetries in network elements such as untransposed lines. Voltage and current unbalance can cause malfunction or reduction in lifetime of different elements. Voltage unbalance has been studied in a variety of publications, due to its high importance and significant effects. However, current unbalance has not gained much attention despite its undeniable influence on transformers’ and line’s lifetime. Observing high values of current unbalance in LV systems is predictable and inevitable. On the other hand, HV systems must be much more balance due to their different structure and absence of large unbalance...

Zero-sum flows in regular graphs

, Article Graphs and Combinatorics ; Volume 26, Issue 5 , 2010 , Pages 603-615 ; 09110119 (ISSN) Akbari, S ; Daemi, A ; Hatami, O ; Javanmard, A ; Mehrabian, A ; Sharif University of Technology

2010

Abstract

For an undirected graph G, a zero-sum flow is an assignment of non-zero real numbers to the edges, such that the sum of the values of all edges incident with each vertex is zero. It has been conjectured that if a graph G has a zero-sum flow, then it has a zero-sum 6-flow. We prove this conjecture and Bouchet's Conjecture for bidirected graphs are equivalent. Among other results it is shown that if G is an r-regular graph (r ≥ 3), then G has a zero-sum 7-flow. Furthermore, if r is divisible by 3, then G has a zero-sum 5-flow. We also show a graph of order n with a zero-sum flow has a zero-sum (n + 3)2-flow. Finally, the existence of k-flows for small graphs is investigated

A Dynamic Mesh Computational Fluid Dynamics Model of Lung on a Chip

, M.Sc. Thesis Sharif University of Technology Mehrabian, Yalda (Author) ; Sani, Mehdi (Supervisor) ; Khayyat, Ali Akbar (Supervisor)

Abstract

Recent investigations on organs-on-chip devices have broadened our insight into the functions of the organs and their responses to pharmaceuticals. Studies on improving the efficiency of these chips are on going. The development of chips for growing various organs and possibly their possible interconnection are other hot topics in this field. This research is an attempt to simulate a Lung-on-a-Chip (LOC) device using Ansys Fluent software. Currently a new experimental technique for setting up a lung-on-a-chip device has been made public (Zamprogno et.al.ˏ̎ Second-generation lung-on-a-Chip with an array of stretchable alveoli made with a biological memvrane ̎ ˏComm. Biologyˏ2021ˏ4:168.). This...

Lead-free MAGeI3 as a suitable alternative for MAPbI3 in nanostructured perovskite solar cells: a simulation study

, Article Environmental Science and Pollution Research ; Volume 30, Issue 19 , 2023 , Pages 57032-57040 ; 09441344 (ISSN) Mehrabian, M ; Akhavan, O ; Rabiee, N ; Afshar, E. N ; Zare, E. N ; Sharif University of Technology

Springer Science and Business Media Deutschland GmbH 2023

Abstract

The lead is a heavy metal with hazardous impacts on environment and human life. Lead-free perovskite solar cells have attracted much attention in recent years, due to eco-friendly characteristics. Meanwhile, Pb-containing cells showed the highest efficiencies among the various types of cells. Hence, designing novel Pb-free solar cells with comparable or better performance than the Pb-containing ones is highly required. In this work, a lead-free methyl-ammonium-germanium-iodide (MAGeI3)-based perovskite solar cell with ITO/TiO2/MAGeI3/Spiro-OMeTAD/Ag multilayer nanostructure has been proposed and its main characteristics including open-circuit voltage (VOC) and power conversion efficiency (η)...

Performance of valveless diffuser micropumps under harmonic piezoelectric actuation

, Article 8th Biennial ASME Conference on Engineering Systems Design and Analysis, ESDA2006, Torino, 4 July 2006 through 7 July 2006 ; Volume 2006 , 2006 ; 0791837793 (ISBN); 9780791837795 (ISBN) Ahmadian, M. T ; Saidi, M. H ; Mehrabian, A ; Bazargan, M ; Kenarsari, S. D ; Sharif University of Technology

American Society of Mechanical Engineers 2006

Abstract

Valveless piezoelectric micropumps are in wide practical use due to their ability to conduct particles with absence of interior moving mechanical parts. The objective of this paper is to obtain the fluid flow response to actuation frequency of a passive diffuser valve under harmonic pressures. In this regards a 2D model of a micropump valves and chambers is analyzed. The analysis is performed for 10Kpa back pressure on micropump chamber and actuation frequencies within the range of 1Hz to 10 KHz. Results show the highest velocity in the direction of diffuser axis occurs at the narrow diffuser neck while flow direction reverses every half period. For low frequencies, a parabolic velocity...

On a bounded budget network creation game

, Article Annual ACM Symposium on Parallelism in Algorithms and Architectures, 4 June 2011 through 6 June 2011, San Jose, CA ; June , 2011 , Pages 207-214 ; 9781450307437 (ISBN) Ehsani, S ; Fazli, M ; Mehrabian, A ; Sadeghian Sadeghabad, S ; Safari, M ; Saghafian, M ; Shokat Fadaee, S ; Sharif University of Technology

2011

Abstract

We consider a network creation game in which, each player (vertex) has a limited budget to establish links to other players. In our model, each link has a unit cost and each agent tries to minimize its cost which is its local diameter or its total distance to other players in the (undirected) underlying graph of the created network. Two variants of the game are studied: in the MAX version, the cost incurred to a vertex is the maximum distance between that vertex and other vertices, and in the SUM version, the cost incurred to a vertex is the sum of distances between that vertex and other vertices. We prove that in both versions pure Nash equilibria exist, but the problem of finding the best...

A bounded budget network creation game

, Article ACM Transactions on Algorithms ; Volume 11, Issue 4 , June , 2015 ; 15496325 (ISSN) Ehsani, S ; Shokat Fadaee, S ; Fazli, M ; Mehrabian, A ; Sadeghian Sadeghabad, S ; Safari, M ; Saghafian, M ; Sharif University of Technology

Association for Computing Machinery 2015

Abstract

We introduce a network creation game in which each player (vertex) has a fixed budget to establish links to other players. In this model, each link has a unit price, and each agent tries to minimize its cost, which is either its eccentricity or its total distance to other players in the underlying (undirected) graph of the created network. Two versions of the game are studied: In the MAX version, the cost incurred to a vertex is the maximum distance between the vertex and other vertices, and, in the SUM version, the cost incurred to a vertex is the sum of distances between the vertex and other vertices. We prove that in both versions pure Nash equilibria exist, but the problem of finding the...