A counterexample to polynomially bounded realizability of basic arithmetic

, Article Notre Dame Journal of Formal Logic ; Volume 60, Issue 3 , 2019 , Pages 481-489 ; 00294527 (ISSN) Ardeshir, M ; Khaniki, E ; Shahriari, M ; Sharif University of Technology

Duke University Press 2019

Abstract

A counterexample to polynomially bounded realizability of basic arithmetic

, Article Notre Dame Journal of Formal Logic ; Volume 60, Issue 3 , 2019 , Pages 481-489 ; 00294527 (ISSN) Ardeshir, M ; Khaniki, E ; Shahriari, M ; Sharif University of Technology

Duke University Press 2019

Abstract

An integrated approach for enhancing the quality of the product by combining robust design and customer requirements

, Article Quality and Reliability Engineering International ; Vol. 30, Issue. 8 , 2014 , pp. 1285-1292 ; ISSN: 07488017 Shahriari, H ; Haji, M. J ; Eslamipoor, R ; Sharif University of Technology

2014

Abstract

Enhancing the quality of the product has always been one considerable concern of production process management, and this subject gave way to implementing so many methods including robust design. In this paper, robust design utilizes response surface methodology (RSM) considering the mean and variance of the response variable regarding system design, parameter design, and tolerance design. In this paper, customer requirements and robust design are regarded simultaneously to achieve enriched quality. Subsequently, with a non-linear programming, a novel method for integrating RSM and quality function deployment has been proposed to achieve robustness in design. The customer requirements are...

γ' Precipitate dissolution during heat treatment of nimonic 115 superalloy

, Article Materials and Manufacturing Processes ; Volume 24, Issue 5 , 2009 , Pages 559-563 ; 10426914 (ISSN) Shahriari, D ; Sadeghi, M. H ; Akbarzadeh, A ; Sharif University of Technology

2009

Abstract

In precipitation hardenable materials, it is desirable to determine the precipitate dissolution temperature for homogenizing the microstructure by controlling the size and distribution of the precipitates. In this research, differential thermal analysis, dilatometry technique, heat treatments followed by microstructure evaluation were used to determine the -γ' dissolution temperature of Nimonic 115. It is assumed that the variation of enthalpy is governed by the changes in y volume fraction and γ concentration with time and temperature, and any contribution of the coarsening of γ' is neglected. The values obtained for the solvus temperature of γ precipitates by the three methods are all in...

Discrete formulation for two-dimensional multigroup neutron diffusion equations

, Article Annals of Nuclear Energy ; Volume 31, Issue 3 , 2004 , Pages 231-253 ; 03064549 (ISSN) Vosoughi, N ; Salehi, A. A ; Shahriari, M ; Sharif University of Technology

2004

Abstract

The objective of this paper is to introduce a new numerical method for neutronic calculation in a reactor core. This method can produce the final finite form of the neutron diffusion equation by classifying the neutronic variables and using two kinds of cell complexes without starting from the conventional differential form of the neutron diffusion equation. The method with linear interpolation produces the same convergence as the linear continuous finite element method. The quadratic interpolation is proven; the convergence order depends on the shape of the dual cell. The maximum convergence order is achieved by choosing the dual cell based on two Gauss' points. The accuracy of the method...

The influence of heat treatment and hot deformation conditions on γ′ precipitate dissolution of Nimonic 115 superalloy

, Article International Journal of Advanced Manufacturing Technology ; Volume 45, Issue 9-10 , 2009 , Pages 841-850 ; 02683768 (ISSN) Shahriari, D ; Sadeghi, M. H ; Akbarzadeh, A ; Cheraghzadeh, M ; Sharif University of Technology

2009

Abstract

In precipitation hardenable materials, it is desirable to determine the precipitate dissolution temperature for homogenizing the microstructure by controlling the size and distribution of the precipitates. In this research, the influence of various heat treatment and hot deformation conditions on the kinetics of γ ′ dissolution and its morphological evolution in Nimonic 115 was studied. In addition, hot deformation behavior of the material was investigated using hot compression experiments at varying temperature (between 1,050°C and 1,175°C) and strain rates (between 0.01 and 1 s-1) up to a true strain of 0.8. The values obtained for the solvus temperature of γ ′ precipitates by two methods...

Direct Discrete Method (DDM) and its application to neutron transport problems

, Article Scientia Iranica ; Volume 14, Issue 1 , 2007 , Pages 78-85 ; 10263098 (ISSN) Vosoughi, N ; Salehi, A. A ; Shahriari, M ; Heshmatzadeh, M ; Sharif University of Technology

Sharif University of Technology 2007

Abstract

The objective of this paper is to introduce a new direct method for neutronic calculations. This method, called Direct Discrete Method (DDM), is simpler than the Neutron Transport Equation and more compatible with the physical meanings of the problem. The method, based on the physics of the problem, initially-runs through meshing of the desired geometry. Next, the balance equation for each mesh interval is written. Considering the connection between the mesh intervals, the final discrete equation series are directly obtained without the need to first pass through the set-up of the neutron transport differential equation. In this paper, a single and multigroup neutron transport discrete...

Plastic injection molding dies using hybrid additively manufactured 420/CX stainless steels: electrochemical considerations

, Article npj Materials Degradation ; Volume 6, Issue 1 , 2022 ; 23972106 (ISSN) Shahriari, A ; Samei, J ; Sanjari, M ; Jahanbakht, M ; Amirkhiz, B. S ; Mohammadi, M ; Sharif University of Technology

Nature Publishing Group 2022

Abstract

This research focused on the corrosion resistance and microstructure of hybrid additively manufactured (HAM) samples of AISI 420/CX (420/CX SS) stainless steels. Potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), and Mott–Schottky analyses as well as the electrochemical noise (EN) technique were used to evaluate the electrochemical behavior of the as-built and heat-treated HAM parts in NaCl solution. The results showed a more protective passive layer formed on the CX SS side. The distribution of Cr-rich M23C6 carbides in matrix of 420 SS side resulted in a lower corrosion resistance compared to the CX SS side. The noise data analysis confirmed an increase in the...

Author Correction: Plastic injection molding dies using hybrid additively manufactured 420/CX stainless steels: electrochemical considerations (npj Materials Degradation, (2022), 6, 1, (70), 10.1038/s41529-022-00280-y)

, Article npj Materials Degradation ; Volume 6, Issue 1 , 2022 ; 23972106 (ISSN) Shahriari, A ; Samei, J ; Sanjari, M ; Jahanbakht, M ; Amirkhiz, B. S ; Mohammadi, M ; Sharif University of Technology

Nature Publishing Group 2022

Analytical modeling of a Minimally Invasive Surgery grasper actuated by shape memory alloy wires

, Article International Conference on Robotics and Mechatronics, ICRoM 2013 ; Feb , 2013 , Pages 147-151 ; 9781467358118 (ISBN) Shahriari, M ; Zabihollah, A ; Sharif University of Technology

2013

Abstract

Minimally Invasive Surgery (MIS) is getting common these days. MIS robots using special tools can perform surgery precisely as humans. This is only possible with dexterous end-effectors and a well-controlled system. Local, lightweight and powerful actuators positioned at end-effectors provide the ability to decrease the degrees of freedom and simplify the design. This paper discusses a grasper design actuated by Shape Memory Alloy (SMA) wires that can be used in MIS robotics. The properties of a commercially available shape memory alloy are explored and analytical formulations for the actuation procedure are developed. The grasper actuated by SMA wires is studied and the procedure of...

Vorticity-Bases Adaptive Mesh Refinement for Upscaling of Highly Heterogeneous Porous Media

, M.Sc. Thesis Sharif University of Technology Shahriari, Arjang (Author) ; Firoozabadi, Bahar (Supervisor)

Abstract

The results of numerical simulation of underground flows are greatly affected not only by the discretization method of flow equations, but also by the way that the geological domain is upscaled. Including the detailed knowledge of heterogeneous permeability distribution is mostly neither feasible nor computationally efficient. So it is important to develop efficient grid generation and upscaling methods to simplify the fine-scale flow model while still including the impact of the heterogeneities as far as possible. Thus regions where parameters of interest have larger values or higher changes require finer grid blocks and regions with lower values or minor changes should have coarser grid...

Consequence Modelling of Ethylene Oxide Reactor of Morvarid Petrochemical Co

, M.Sc. Thesis Sharif University of Technology Shahriari, Esmaeel (Author) ; Rashtchian, Davood (Supervisor)

Abstract

As Ethylene Oxide is a highly toxic, flammable, and hazardous material, the consequences of any malfunction in an Ethylene Oxide reactor may be irreparable. The aim of this thesis is to evaluate the probable consequences of an accident in Morvarid Petrochemical Co.’s Ethylene Oxide Reactor in order to find probable hazardous scenarios. In this project, probable accidents were modelled and evaluated by Phast software in different scenarios, and the outcomes were investigated. In addition, if necessary, a set of solutions were proposed to decrease casualties in hazardous scenarios. The results may be used to change layouts according to Consequence Modelling. Results illustrated that...

Control of Three-phase UPS with Nonlinear Load Using Disturbance Observer Considering Transformer Concerns

, M.Sc. Thesis Sharif University of Technology Shahriari, Zohair (Author) ; Tahami, Farzad (Supervisor)

Abstract

Nowadays, non-linear loads comprise an important part of electrical grids. One of the most essential sources of nonlinear loads is switching power supplies, which mainly include power electronic rectifiers. When power outage occurs, Uninterruptible Power Supplies (UPS) must be able to supply these loads. The nonlinearity of the load has a significant effect on the Total Harmonic Distortion (THD) of the output voltage, which may not be easily reduced, especially in three-phase inverters. Furthermore, the presence of isolating transformers in these power supplies limits the control of harmonics and intensifies the nonlinear effects of the system.In this Master Thesis, a disturbance observer is...

Constructive Mathematics and Quantum Mechanics

, M.Sc. Thesis Sharif University of Technology Shahriari, Mohsen (Author) ; Ardeshir, Mohammad (Supervisor)

Abstract

In constructive mathematics, one has to construct a mathematical object in order to show that it exists. Consequently, some of classical theorems are not acceptable from a constructive point of view. In particular, the constructive validity of the parts of mathematics that play a role in forming physical theories is of interest. Here, we want to examine the constructive provability of some theorems related to quantum mechanics

Vulnerability analysis of networks to detect multiphase attacks using the actor-based language Rebeca

, Article Computers and Electrical Engineering ; Volume 36, Issue 5 , 2010 , Pages 874-885 ; 00457906 (ISSN) Shahriari, H. R ; Makarem, M. S ; Sirjani, M ; Jalili, R ; Movaghar, A ; Sharif University of Technology

2010

Abstract

Increasing use of networks and their complexity make the task of security analysis more and more complicated. Accordingly, automatic verification approaches have received more attention recently. In this paper, we investigate applying of an actor-based language based on reactive objects for analyzing a network environment communicating via Transport Protocol Layer (TCP). The formal foundation of the language and available tools for model checking provide us with formal verification support. Having the model of a typical network including client and server, we show how an attacker may combine simple attacks to construct a complex multiphase attack. We use Rebeca language to model the network...

New dictionary learning methods for two-dimensional signals

, Article 28th European Signal Processing Conference, EUSIPCO 2020, 24 August 2020 through 28 August 2020 ; Volume 2021-January , 2021 , Pages 2021-2025 ; 22195491 (ISSN); 9789082797053 (ISBN) Shahriari Mehr, F ; Parsa, J ; Babaie Zadeh, M ; Jutten, C ; Sharif University of Technology

European Signal Processing Conference, EUSIPCO 2021

Abstract

By growing the size of signals in one-dimensional dictionary learning for sparse representation, memory consumption and complex computations restrict the learning procedure. In applications of sparse representation and dictionary learning in two-dimensional signals (e.g. in image processing), if one opts to convert two-dimensional signals to one-dimensional ones, and use the existing one-dimensional dictionary learning and sparse representation techniques, too huge signals and dictionaries will be encountered. Two-dimensional dictionary learning has been proposed to avoid this problem. In this paper, we propose two algorithms for two-dimensional dictionary learning. According to our...

Detection of distributed denial of service attacks using statistical pre-processor and unsupervised neural networks

, Article First International Conference on Information Security, Practice and Experience, ISPEC 2005, 11 April 2005 through 14 April 2005 ; Volume 3439 , 2005 , Pages 192-203 ; 03029743 (ISSN) Jalili, R ; Imani Mehr, F ; Amini, M ; Shahriari, H. R ; Sharif University of Technology

Springer Verlag 2005

Abstract

Although the prevention of Distributed Denial of Service (DDoS) attacks is not possible, detection of such attacks plays main role in preventing their progress. In the flooding attacks, especially new sophisticated DDoS, the attacker floods the network traffic toward the target computer by sending pseudo-normal packets. Therefore, multi-purpose IDSs do not offer a good performance (and accuracy) in detecting such kinds of attacks. In this paper, a novel method for detection of DDoS attacks has been introduced based on a statistical pre-processor and an unsupervised artificial neural net. In addition, SPUNNID system has been designed based on the proposed method. The statistical...

Gait analysis of a six-legged walking robot using fuzzy reward reinforcement learning

, Article 13th Iranian Conference on Fuzzy Systems, IFSC 2013 ; August , 2013 , Page(s): 1 - 4 ; ISBN: 9781479912278 Shahriari, M ; Khayyat, A. A ; Sharif University of Technology

IEEE Computer Society 2013

Abstract

Free gait becomes necessary in walking robots when they come to walk over discontinuous terrain or face some difficulties in walking. A basic gait generation strategy is presented here using reinforcement learning and fuzzy reward approach. A six-legged (hexapod) robot is implemented using Q-learning algorithm. The learning ability of walking in a hexapod robot is explored considering only the ability of moving its legs and using a fuzzy rewarding system telling whether and how it is moving forward. Results show that the hexapod robot learns to walk using the presented approach properly

Vulnerability take grant (VTG): an efficient approach to analyze network vulnerabilities

, Article Computers and Security ; Volume 26, Issue 5 , 2007 , Pages 349-360 ; 01674048 (ISSN) Shahriari, H. R ; Jalili, R ; Sharif University of Technology

2007

Abstract

Modeling and analyzing information system vulnerabilities help predict possible attacks to computer networks using vulnerabilities information and the network configuration. In this paper, we propose a comprehensive approach to analyze network vulnerabilities in order to answer the safety problem focusing on vulnerabilities. The approach which is called Vulnerability Take Grant (VTG) is a graph-based model consists of subject/objects as nodes and rights/relations as edges to represent the system protection state. Each node may have properties including single vulnerabilities such as buffer overflow. We use the new concept of vulnerability rewriting rule to specify the requirements and...

Using CSP to model and analyze transmission control protocol vulnerabilities within the broadcast network

, Article Proceedings - 2004 International Networking and Communication Conference, INCC 2004, Lahore, 11 June 2004 through 13 June 2004 ; 2004 , Pages 42-47 ; 0780383257 (ISBN) Shahriari, H. R ; Jalili, R ; Sharif University of Technology

2004

Abstract

Spreading networks and increasing their complexity has complicated the task of security analysis. Accordingly, automatic verification approaches have received more attention recently. In this paper, we modeled a network including a set of hosts (clients and servers) using the process algebra CSP in order to verify the Transmission Control Protocol (TCP) behavior against an active intruder. The model is verified using the FDR tool and as a result, some attack scenarios violating the security are found. The scenarios showes how an intruder can compromise the server trust to its clients. As the model is modular, extendable, and scalable, more complex attack scenarios (combination of simple...