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Numerical investigation of the unstart suppression in a supersonic air intake
, Article Iranian Journal of Science and Technology - Transactions of Mechanical Engineering ; Volume 39, Issue M2 , 2015 , Pages 413-426 ; 22286187 (ISSN) ; Sepahi Younsi, J ; Farajpoor Khanaposhtani, V ; Sharif University of Technology
Shiraz University
2015
Abstract
The starting behavior of a supersonic axisymmetric mixed compression air intake was numerically investigated. The code solves Reynolds-Averaged Navier-Stokes equations using an explicit finite volume method in a structured grid by the Roe flux difference splitting scheme. Further, it uses the Baldwin-Lomax algebraic model to compute the turbulent viscosity coefficient. The correct method of surveying the intake starting problem and effects of several geometrical parameters such as: intake throat area, cowl lip roundness and spike surface curvature upstream of the throat on the starting and performance of the intake were studied. Results showed that correct combinations of the mentioned...
Solving the Cold-Start Problem in Recommender Systems Personalization
, M.Sc. Thesis Sharif University of Technology ; Rabie, Hamid Reza (Supervisor)
Abstract
User cold-start is a common problem among real-world applications in the sequential recommendation field since determining user preference based on a few interactions is difficult. The problem would end up limiting the performance recommender systems. To address the cold-start problem, some previous works used meta-learning along with user’s and item’s side information. Meta-learning algorithms made the model able to share knowledge among all tasks. Although they had promising results, they had some fundamental issues with modeling the dynamics of user preferences and considering all kinds of users’ preferences, especially for minor users. The proposed method includes a model incorporating...
Boundary layer suction for high-speed air intakes: A review
, Article Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering ; 2018 ; 09544100 (ISSN) ; Forouzi Feshalami, B ; Maadi, S. R ; Soltani, M. R ; Sharif University of Technology
SAGE Publications Ltd
2018
Abstract
The paper summarizes recent developments in boundary layer suction for high-speed air intakes. Bleed has been efficiently used in supersonic and hypersonic intakes for three primary reasons: to improve the performance of the intake, to reduce the starting Mach number of the intake, and to postpone the onset of buzz oscillations. A bleed system has many characteristics such as the bleed entrance and exit areas, bleed entrance slant angle and position, and bleed type (slot or porous and ram-scoop or flush). Each of these parameters has significant impacts on the intake performance and stability that have been reviewed in this study. In addition, the effectiveness of other flow control methods...
Boundary layer suction for high-speed air intakes: A review
, Article Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering ; Volume 233, Issue 9 , 2019 , Pages 3459-3481 ; 09544100 (ISSN) ; Forouzi Feshalami, B ; Maadi, S. R ; Soltani, M. R ; Sharif University of Technology
SAGE Publications Ltd
2019
Abstract
The paper summarizes recent developments in boundary layer suction for high-speed air intakes. Bleed has been efficiently used in supersonic and hypersonic intakes for three primary reasons: to improve the performance of the intake, to reduce the starting Mach number of the intake, and to postpone the onset of buzz oscillations. A bleed system has many characteristics such as the bleed entrance and exit areas, bleed entrance slant angle and position, and bleed type (slot or porous and ram-scoop or flush). Each of these parameters has significant impacts on the intake performance and stability that have been reviewed in this study. In addition, the effectiveness of other flow control methods...
A matrix factorization model for hellinger-based trust management in social internet of things
, Article IEEE Transactions on Dependable and Secure Computing ; Volume 19, Issue 4 , 2022 , Pages 2274-2285 ; 15455971 (ISSN) ; Mahyar, H ; Movaghar, A ; Stanley, H. E ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2022
Abstract
The Social Internet of Things (SIoT), integration of the Internet of Things, and Social Networks paradigms, has been introduced to build a network of smart nodes that are capable of establishing social links. In order to deal with misbehaving service provider nodes, service requestor nodes must evaluate their trustworthiness levels. In this article, we propose a novel trust management mechanism in the SIoT to predict the most reliable service providers for each service requestor, which leads to reduce the risk of being exposed to malicious nodes. We model the SIoT with a flexible bipartite graph (containing two sets of nodes: service providers and service requestors), then build a social...