A model based approach on multi-agent system and genetic algorithm to improve the process management in service oriented architecture

, Article Journal of Telecommunication, Electronic and Computer Engineering ; Volume 8, Issue 5 , 2016 , Pages 33-40 ; 21801843 (ISSN) Nahvi, B ; Habibi, J ; Sharif University of Technology

UniversityTeknikal Malaysia Melaka 2016

Abstract

Service oriented architecture is based on the provision of services. To enhance the performance of the systems by providing a better combination of services, it is necessary to extract more information compared to the one in the service registry. In this regard, the accomplished works have been focusing on the basic concepts of service-oriented architecture. The service composition is based on the information in service registry, provided by the service provider. Further, centralized combination with insufficient information does not meet the system performance requirements. This solution helps to facilitate resource distribution and reduces tasks of the central unit. In this paper, efforts...

The Existence of Subgraphs with Given Properties

, M.Sc. Thesis Sharif University of Technology Nahvi, Mina (Author) ; Akbari, Saeed (Supervisor)

Abstract

Let G be a graph. We call G an odd graph if all its vertices have odd degrees. Caro conjectured that for every graph G and every integer k, k > 2, there exists a Zk-coloring for the vertices of G so that for all v 2 V (G), the sum of the colors of all vertices in N[v] is not congruent to 0 modulo k. This thesis is mainly devoted to determining a lower bound for the number of vertices of the largest odd induced subgraph of a given graph with no isolated vertices. Another focus of this thesis is to find an upper bound for the number of odd induced subgraphs, as well as odd induced forests, needed to partition V (G), where G is a given graph with even order. At the end, two variations of Caro’s...

Inverse degree index of graphs with a given cyclomatic number

, Article Filomat ; Volume 37, Issue 27 , 2023 , Pages 9371-9376 ; 03545180 (ISSN) Akbari, S ; Doslic, T ; Nahvi, N ; Sharif University of Technology

University of Nis 2023

Abstract

We investigate how the inverse degree index of graphs depends on their cyclomatic number. In particular, we provide sharp lower bounds on the inverse degree index over all graphs on a given number of vertices with a given cyclomatic number. We also deduce some structural properties of extremal graphs. Some open questions regarding the upper bound over the same class of graphs are discussed and some possible further developments are indicated. © 2023, University of Nis. All rights reserved

Investigating the effect of engine noise on power management strategy of a hybrid electric vehicle

, Article Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering ; Volume 232, Issue 10 , 2018 , Pages 1287-1296 ; 09544070 (ISSN) Delkhosh, M ; Aliramezani, M ; Khadem Nahvi, M ; Sharif University of Technology

SAGE Publications Ltd 2018

Abstract

Hybrid electric vehicles (HEVs) have been developed as a promising way to decrease the fuel consumption and emissions of conventional vehicles. Although the noise emission of HEVs is generally lower than that of conventional vehicles, it is still an issue, especially in urban transportation. In this paper, a power management strategy is developed to minimize the annoying noise of the engine for an HEV. This is a modified version of the strategy that was originally established based on the speed ratio of continuously variable transmission (CVT) as the control parameter (CVT-based strategy). The engine combustion noise is assessed using the experimental data of the in-cylinder pressure. Also,...

Nordhaus–Gaddum and other bounds for the chromatic edge-stability number

, Article European Journal of Combinatorics ; Volume 84 , 2020 Akbari, S ; Klavžar, S ; Movarraei, N ; Nahvi, M ; Sharif University of Technology

Academic Press 2020

Abstract

Let G be a graph. The chromatic edge-stability number esχ(G) of a graph G is the minimum number of edges of G whose removal results in a graph H with χ(H)=χ(G)−1. A Nordhaus–Gaddum type inequality for the chromatic edge-stability number is proved. Sharp upper bounds on esχ are given for general graphs in terms of size and of maximum degree, respectively. All bounds are demonstrated to be sharp. Graphs with esχ=1 are considered and in particular characterized among k-regular graphs for k≤5. Several open problems are also stated. © 2019 Elsevier Ltd

Some criteria for a signed graph to have full rank

, Article Discrete Mathematics ; Volume 343, Issue 8 , 2020 Akbari, S ; Ghafari, A ; Kazemian, K ; Nahvi, M ; Sharif University of Technology

Elsevier B.V 2020

Abstract

A weighted graph Gω consists of a simple graph G with a weight ω, which is a mapping, ω: E(G)→Z∖{0}. A signed graph is a graph whose edges are labelled with −1 or 1. In this paper, we characterize graphs which have a sign such that their signed adjacency matrix has full rank, and graphs which have a weight such that their weighted adjacency matrix does not have full rank. We show that for any arbitrary simple graph G, there is a sign σ so that Gσ has full rank if and only if G has a {1,2}-factor. We also show that for a graph G, there is a weight ω so that Gω does not have full rank if and only if G has at least two {1,2}-factors. © 2020 Elsevier B.V

Uses of Multi Speed Gearbox to Improve Infinitely Variable Transmission Performance

, M.Sc. Thesis Sharif University of Technology Khadem Nahvi, Mehdi (Author) ; Saadat Foumani, Mahmoud (Supervisor)

Abstract

In recent decades, the air pollution issue and fuel resource constraints have compelled researchers to find ways to replace fossil fuels or reduce their consumption. Since the Vehicles are one of the most important sources of pollution and energy consumer, efforts to reduce vehicles fuel consumption can be an effective action to reduce air pollution. A proper powertrain system has an important task to reduce fuel consumption and air pollution.
Uses of continuously variable transmission system (CVT) and infinitely variable transmission (IVT), which makes the internal combustion engine to operate in optimal condition, can help to achieve this goal. In this thesis, the target is find...

Improvement of Stability of Haptic Force Interaction with Virtual Environments Using a Haptic Interface with a Separate Tracker

, M.Sc. Thesis Sharif University of Technology Mashayekhi, Ahmad (Author) ; Meghdari, Ali (Supervisor) ; Nahvi, Ali (Supervisor)

Abstract

In the present study, a new version of haptic devices is presented in which user’s hand is in contact with the device just while collision with virtual surface. In this system, the position of user’s finger can be traced by using a camera and the haptic device follows user’s finger at the distance of about two centimeters. While the haptic device approaches to the virtual surface, gradually reduces its speed and stops about two centimeters distant of virtual plane. Then user’s hand collides with the haptic device which is static. Greater fidelity, transparency, more stability and also no need to large actuators are of the advantages of this system. In this project, first we present a new...

Improved passivity criterion in haptic rendering: influence of coulomb and viscous friction [electronic resource]

, Article Advanced Robotics ; 2014 Volume 28, Issue 10 Mashayekhi, A. (Ahmad) ; R. Bozorgmehry, R ; Nahvi, A ; Meghdari, A ; Asgari, P ; Sharif University of Technology

Abstract

In this paper, a new criterion for passivity of haptic devices is obtained. This criterion creates a relationship between Coulomb friction coefficient, viscous friction coefficient, sampling rate, and the maximum simulated stiffness. The process of derivation of the passivity criterion is described in detail. This criterion is improved compared with other existing criteria and predicts passivity in haptic rendering more accurately. In particular, for speeds of less than 5 cm/s, the new passivity criterion should replace the previous criteria to avoid unwanted vibrations of stiff virtual walls. Analytical and numerical investigations are presented to validate the new criterion. A specific...

Mixed paths and cycles determined by their spectrum

, Article Linear Algebra and Its Applications ; Volume 586 , 2020 , Pages 325-346 Akbari, S ; Ghafari, A ; Nahvi, M ; Nematollahi, M. A ; Sharif University of Technology

Elsevier Inc 2020

Abstract

A mixed graph is obtained from a graph by orienting some of its edges. The Hermitian adjacency matrix of a mixed graph with the vertex set {v1,…,vn}, is the matrix H=[hij]n×n, where hij=−hji=i if there is a directed edge from vi to vj, hij=1 if there exists an undirected edge between vi and vj, and hij=0 otherwise. The Hermitian spectrum of a mixed graph is defined to be the spectrum of its Hermitian adjacency matrix. In this paper we study mixed graphs which are determined by their Hermitian spectrum (DHS). First, we show that each mixed cycle is switching equivalent to either a mixed cycle with no directed edges (Cn), a mixed cycle with exactly one directed edge (Cn 1), or a mixed cycle...

Application of multi-speed gearbox in infinitely variable transmission

, Article Iranian Journal of Science and Technology - Transactions of Mechanical Engineering ; Volume 41, Issue 2 , 2017 , Pages 149-157 ; 22286187 (ISSN) Khadem Nahvi, M ; Delkhosh, M ; Foumani, M. S ; Rostami, P ; Sharif University of Technology

Shiraz University 2017

Abstract

One way to reduce vehicles' fuel consumption (FC) is to optimize different parts of its powertrain. Among different modern powertrains, continuously variable transmission (CVT) is one of the common types which changes speed ratio between engine and wheels, continuously. Therefore, the CVT allows the engine to operate at its fuel-optimal speed. Due to the limited power transmission capacity and speed ratio range of the CVT, researchers attempted to combine the CVT with a planetary gear train and a fixed ratio mechanism. This mechanism is called infinitely variable transmission (IVT). In this study, a multi-speed gearbox (MSG) is used in the IVT and its impact on the powertrain performance and...

Graphs with integer matching polynomial zeros

, Article Discrete Applied Mathematics ; 2017 ; 0166218X (ISSN) Akbari, S ; Csikvári, P ; Ghafari, A ; Khalashi Ghezelahmad, S ; Nahvi, M ; Sharif University of Technology

Elsevier B. V 2017

Abstract

In this paper, we study graphs whose matching polynomials have only integer zeros. A graph is matching integral if the zeros of its matching polynomial are all integers. We characterize all matching integral traceable graphs. We show that apart from K7(set minus)(E(C3)∪E(C4)) there is no connected k-regular matching integral graph if k≥2. It is also shown that if G is a graph with a perfect matching, then its matching polynomial has a zero in the interval (0,1]. Finally, we describe all claw-free matching integral graphs

Graphs with integer matching polynomial zeros

, Article Discrete Applied Mathematics ; Volume 224 , 2017 , Pages 1-8 ; 0166218X (ISSN) Akbari, S ; Csikvári, P ; Ghafari, A ; Khalashi Ghezelahmad, S ; Nahvi, M ; Sharif University of Technology

2017

Abstract

In this paper, we study graphs whose matching polynomials have only integer zeros. A graph is matching integral if the zeros of its matching polynomial are all integers. We characterize all matching integral traceable graphs. We show that apart from K7∖(E(C3)∪E(C4)) there is no connected k-regular matching integral graph if k≥2. It is also shown that if G is a graph with a perfect matching, then its matching polynomial has a zero in the interval (0,1]. Finally, we describe all claw-free matching integral graphs. © 2017 Elsevier B.V

Using self-adaptive evolutionary algorithm to improve the performance of an extreme learning machine for estimating soil temperature

, Article Computers and Electronics in Agriculture ; Volume 124 , 2016 , Pages 150-160 ; 01681699 (ISSN) Nahvi, B ; Habibi, J ; Mohammadi, K ; Shamshirband, S ; Al Razgan, O. S ; Sharif University of Technology

Elsevier B.V 2016

Abstract

In this study, the self-adaptive evolutionary (SaE) agent is employed to structure the contributing elements to process the management of extreme learning machine (ELM) architecture based on a logical procedure. In fact, the SaE algorithm is utilized for possibility of enhancing the performance of the ELM to estimate daily soil temperature (ST) at 6 different depths of 5, 10, 20, 30, 50 and 100 cm. In the developed SaE-ELM model, the network hidden node parameters of the ELM are optimized using SaE algorithm. The precision of the SaE-ELM is then compared with the ELM model. Daily weather data sets including minimum, maximum and average air temperatures (Tmin, Tmax and Tavg), atmospheric...

Microwave-induced Cannizzaro reaction over neutral γ-alumina as a polymeric catalyst [electronic resource]

, Article Reactive and Functional Polymers ; 01/2002; 51(1):49-53 Pourjavadi, A. (Ali) ; Soleimanzadeh, B ; Marandi, G. B

Abstract

γ-Alumina is used to catalyze the Cannizzaro reaction in the absence of any base under microwave irradiation in high yields. In the case of terephthalaldehyde the reaction is carried out with high selectivity

SnCl4/SiO2: an efficient heterogeneous alternative for one-pot synthesis of β-acetamidoketones

, Article Journal of the Chinese Chemical Society ; Volume 56, Issue 2 , 2009 , Pages 386-391 ; 00094536 (ISSN) Mirjalili, B. B. F ; Mahmoodi Hashemi, M ; Sadeghi, B ; Emtiazi, H ; Sharif University of Technology

2009

Abstract

Enolizable ketones have been reacted in a one-pot method with aromatic aldehydes, acetyl chloride and acetonitrile at room temperature in the presence of SnCl4/SiO2 to furnish the corresponding β-acetamidoketones in improved yields. Acetylation of an aromatic hydroxyl group was observed while using 4-hydroxybenzaldehyde or vanillin and the corresponding β-acetamidoketones were isolated in an excellent yield

Turbulent flow in converging nozzles, part one: Boundary layer solution

, Article Applied Mathematics and Mechanics (English Edition) ; Volume 32, Issue 5 , 2011 , Pages 645-662 ; 02534827 (ISSN) Maddahian, R ; Farhanieh, B ; Firoozabadi, B ; Sharif University of Technology

2011

Abstract

The boundary layer integral method is used to investigate the development of the turbulent swirling flow at the entrance region of a conical nozzle. The governing equations in the spherical coordinate system are simplified with the boundary layer assumptions and integrated through the boundary layer. The resulting sets of differential equations are then solved by the fourth-order Adams predictor-corrector method. The free vortex and uniform velocity profiles are applied for the tangential and axial velocities at the inlet region, respectively. Due to the lack of experimental data for swirling flows in converging nozzles, the developed model is validated against the numerical simulations. The...

Numerical investigation of steady density currents flowing down an incline using v2̄ - F turbulence model

, Article Journal of Fluids Engineering, Transactions of the ASME ; Volume 129, Issue 9 , 2007 , Pages 1172-1178 ; 00982202 (ISSN) Khakzad, N ; Firoozabadi, B ; Farhanieh, B ; Sharif University of Technology

2007

Abstract

The governing equations of two-dimensional steady density currents are solved numerically using a finite volume method. The v2̄-f turbulence model, based on standard k - s model, is used for the turbulence closure. In this method, all Reynolds stress equations are replaced with both a transport equation for v2̄ and an elliptic relaxation equation for f, a parameter closely related to the pressure strain redistribution term. The Simple-C procedure is used for pressure-velocity coupling. In addition, Boussinesq's approximation is used to obtain the momentum equation. The computed height of the progressive density current is compared to the measured data in the literature, resulting in good...

Numerical simulation of turbid-density current using v2̄ - f turbulence model

, Article 2005 ASME International Mechanical Engineering Congress and Exposition, IMECE 2005, Orlando, FL, 5 November 2005 through 11 November 2005 ; Volume 261 FED , 2005 , Pages 619-627 ; 08888116 (ISSN); 0791842193 (ISBN); 9780791842195 (ISBN) Mehdizadeh, A ; Firoozabadi, B ; Farhanieh, B ; Sharif University of Technology

2005

Abstract

The deposition behavior of fine sediment is an important phenomenon, and yet unclear to engineers concerned about reservoir sedimentation. An elliptic relaxation turbulence model (v2̄ - f model) has been used to simulate the motion of turbid density currents laden whit fine solid particles. During the last few years, the v2̄ - f turbulence model has become increasingly popular due to its ability to account for near-wall damping without use of damping functions. In addition, it has been proved that the v2̄ - f model to be superior to other RANS methods in many fluid flows where complex flow features are present. Due to low Reynolds number turbulence of turbidity current,(its critical Reynolds...

Analytical solution for creeping motion of a viscoelastic drop falling through a Newtonian fluid

, Article Korea Australia Rheology Journal ; Vol. 26, issue. 1 , 2014 , pp. 91-104 ; ISSN: 1226119X Vamerzani, B. Z ; Norouzi, M ; Firoozabadi, B ; Sharif University of Technology

2014

Abstract

In this paper, an analytical solution for steady creeping motion of viscoelastic drop falling through a viscous Newtonian fluid is presented. The Oldroyd-B model is used as the constitutive equation. The analytical solutions for both interior and exterior flows are obtained using the perturbation method. Deborah number and capillary numbers are considered as the perturbation parameters. The effect of viscoelastic properties on drop shape and motion are studied in detail. The previous empirical studies indicated that unlike the Newtonian creeping drop in which the drop shape is exactly spherical, a dimpled shape appears in viscoelastic drops. It is shown that the results of the present...