Phase Extraction in Segmented Flow

, M.Sc. Thesis Sharif University of Technology Amini, Mohammad (Author) ; Moosavi, Ali (Supervisor)

Abstract

The formation of droplets at a T-junction in a micro channel network is primarily influenced by the pressure difference across the interface in the squeezing regime. Accurate measurements of droplet velocity and pressure profiles are difficult to obtain experimentally, yet these are the basic parameters required. Droplet micro ﬂuidics has shown great potential for biological assays, chemical reactions and polymer emulsions. High stability allows the droplets to work as stable and isolated reactors that open up for parallel and serial reactions where each droplet can be screened individually. The purpose was to fabricate such systems, establish stable droplet generation where droplet volumes...

Online Health Monitoring of Nonlinear Hysteretic Structures Using System Identification Techniques and Signal Processing Tools

, Ph.D. Dissertation Sharif University of Technology Amini Tehrani, Hamed (Author) ; Bakhshi, Ali (Supervisor)

Abstract

Adverse social and economic effects of earthquakes have necessitated the emergence and development of efficient methods to assess and monitor the health status of structures. Many of the structural health monitoring algorithms are based on linear models that are not able to provide sufficient dynamic information. Nonlinear models require monitoring of a larger number of structural parameters and provide a much closer to reality model of the structure. Therefore, the use of nonlinear models in the identification process provides more useful information about the safety and serviceability of post-earthquake structures. Also, most of the existing methods are not applicable for online health...

Simulation of Cell and Particle Separation by Combination of Dielectrophoretic and Inertial Forces in a Microfluidic Device

, M.Sc. Thesis Sharif University of Technology Sorour Amini, Hossein (Author) ; Mohammadi, Ali Asghar (Supervisor)

Abstract

In this study, the dynamics of microparticles in a straight microchannel in the presence of an inhomogeneous oscillating electric field have been simulated by the immersed boundary method in combination with the lattice Boltzmann Navier-Stokes solver and the lattice Boltzmann method for solving the Poisson equation. The effect of the electric field on the location and number of particle equilibrium positions have been examined. In the absence of the electric field, circular particles will migrate to two stable equilibrium positions. The site of these equilibrium positions depends on the particle size and the fluid flow rate and is independent of the particle density. In the case of negative...

Effective Connectivity Analysis in Neural circuitry Underlying Perceptual and Value-based Memory

, M.Sc. Thesis Sharif University of Technology Fakharian, Mohammad Amin (Author) ; Amini, Arash (Supervisor) ; Ghazizadeh, Ali (Co-Supervisor)

Abstract

Perceptual memory used in novel vs familiar discrimination is not only vital for the evaluation of environmental variations but also essential for learning, perception, and correcting behavioral policies. On the other hand, value-based memory which allows for discrimination of valuable objects among equally familiar ones also drives behavioral interactions and decision making. Although many studies have been conducted to address the neuronal association regarding each separately, the neural correspondence between perceptual and value-based memory is not scrutinized adequately. To this end, the diﬀerential neural activation in two macaque monkeys to unrewarded novel vs familiar fractals (>100...

Enhanced Neural Source Localization by Exploiting the Relation between EEG and fMRI

, M.Sc. Thesis Sharif University of Technology Ataie, Ali (Author) ; Amini, Arash (Supervisor) ; Ghazizadeh Ehsaei, Ali (Supervisor)

Abstract

Electroencephalography (EEG) and the functional magnetic resonance imaging (fMRI) are the two important non-invasive tools in probing the neural activity of human brain. EEG has a high temporal resolution while suffering a low spatial one. On the other hand, fMRI has a superior spatial resolution while offering a low temporal one. Enhancement of the spatial resolution of EEG source localization methods is of high importance due to multiple reasons such as its lower capital and operational costs compared with fMRI, its mobility and ease of use and extra. But all the EEG source localization methods have been the subject to a major problem, and it is absence of a ground-truth about the real...

Access Control System with Access Delegation in E-Health

, M.Sc. Thesis Sharif University of Technology Ghofrani, Faegheh (Author) ; Afshin Hemmatyar, Ali Mohammad (Supervisor) ; Amini, Morteza (Supervisor)

Abstract

In electronic health, data is stored and retrieved electronically at the local or national level for clinical, educational and administrative purposes. The importance of data from citizens, patients, professionals and providers of healthcare and policy-makers points of view make it a valuable asset. In recent years, we confront the emergence of the Internet of Things and its widespread use in electronic health. In this area, health sensors such as a heart rate sensor, a blood glucose sensor, or a respiratory sensor provide information about each person that can be sent through the network to the physician. Such a continuous remote monitoring allows physicians to take better care of patients...

Modelling of queue length in freeway work zones – case study karaj-tehran freeway

, Article Promet - Traffic - Traffico ; Volume 33, Issue 1 , 2021 , Pages 49-59 ; 03535320 (ISSN) Mousazadeh Gilandeh , M ; Sharif Ali , S ; Goodarzi, M. J ; Amini, N ; Latifi, H ; Sharif University of Technology

Faculty of Transport and Traffic Engineering 2021

Abstract

In this study, the traffic parameters were collected from three work zones in Iran in order to evaluate the queue length in the work zones. The work zones were observed at peak and non-peak hours. The results showed that abrupt changes in Freeway Free Speed (FFS) and arrival flow rate caused shockwaves and created a bot-tleneck in that section of the freeway. In addition, accel-eration reduction, abrupt change in the shockwave speed, abrupt change in the arrival flow rate and increase in the percentage of heavy vehicles have led to extreme queue lengths and delay. It has been found that using daily traffic data for scheduling the maintenance and rehabilita-tion projects could diminish the...

Copper(II) acetate

, Article Synlett ; Volume 23, Issue 13 , 2012 , Pages 1995-1996 ; 09365214 (ISSN) Amini, M ; Sharif University of Technology

2012

Abstract

(A) Chakraborty and co-workers have developed a green method for the bulk ring-opening polymerization of lactides in the presence of Cu(OAc)2 as a good catalyst to synthesize polymers with different end-terminal groups.3 These polymerizations are highly controlled leading to the formation of polymers with the expected number of average molecular weights and narrow molecular weight distribution. (B) Garden and co-workers have found that the oxidative addition of anilines with 1,4-naphthoquinone to give N-aryl-2-amino-1,4-naphthoquinones can be performed in the presence of catalytic amounts of copper(II) acetate.4 All the reactions are generally more efficient in that they are cleaner, higher...

Solving rank one revised linear systems by the scaled ABS method

, Article ANZIAM Journal ; Volume 46, Issue 2 , 2004 , Pages 225-236 ; 14461811 (ISSN) Amini, K ; Sharif University of Technology

2004

Abstract

In mathematical programming, an important tool is the use of active set strategies to update the current solution of a linear system after a rank one change in the constraint matrix. We show how to update the general solution of a linear system obtained by use of the scaled ABS method when the matrix coefficient is subjected to a rank one change. © Australian Mathematical Society 2004

Dextran-graft-poly(hydroxyethyl methacrylate) gels: A new biosorbent for fluoride removal of water

, Article Designed Monomers and Polymers ; Volume 16, Issue 2 , 2013 , Pages 127-136 ; 1385772X (ISSN) Ahmari, A ; Mousavi, S. A ; Amini Fazl, A ; Amini Fazl, M. S ; Ahmari, R ; Sharif University of Technology

2013

Abstract

Synthesis of dextran-graft-poly(hydroxyethyl methacrylate) gels as a new fluoride biosorbent was considered in this work. For this propose, the Taguchi experimental design method was used for optimizing the synthetic conditions of the gels to reach high level of fluoride absorbency. The effects of three main parameters including concentrations of monomer (hydroxyethyl methacrylate), crosslinking agent (ethylene glycol dimethacrylate), and initiator (ammonium persulfate) on the final properties of the prepared gels were investigated. The proposed mechanism for grafting and chemically crosslinking reactions was proved with equilibrium water absorption, Fourier-transformed infrared, scanning...

Optimization of synthetic conditions of a novel collagen-based superabsorbent hydrogel by Taguchi method and investigation of its metal ions adsorption

, Article Journal of Applied Polymer Science ; Volume 102, Issue 5 , 2006 , Pages 4878-4885 ; 00218995 (ISSN) Pourjavadi, A ; Salimi, H ; Amini Fazl, M. S ; Kurdtabar, M ; Amini Fazl, A. R ; Sharif University of Technology

2006

Abstract

A novel biopolymer-based superabsorbent hydrogel was synthesized through chemical crosslinking by graft copolymerization of partially neutralized acrylic acid onto the hydrolyzed collagen, in the presence of a crosslinking agent and a free radical initiator. The Taguchi method, a robust experimental design, was employed for the optimization of the synthesis reaction based on the swelling capacity of the hydrogels. This method was applied for the experiments and standard L16 orthogonal array with three factors and four levels were chosen. The critical parameters that have been selected for this study are crosslinker (N,N′-methylene bisacrylamide), initiator (potassium persulfate), and monomer...

Sparsity and infinite divisibility

, Article IEEE Transactions on Information Theory ; Volume 60, Issue 4 , 2014 , Pages 2346-2358 ; ISSN: 00189448 Amini, A ; Unser, M ; Sharif University of Technology

2014

Abstract

We adopt an innovation-driven framework and investigate the sparse/compressible distributions obtained by linearly measuring or expanding continuous-domain stochastic models. Starting from the first principles, we show that all such distributions are necessarily infinitely divisible. This property is satisfied by many distributions used in statistical learning, such as Gaussian, Laplace, and a wide range of fat-tailed distributions, such as student's-t and α-stable laws. However, it excludes some popular distributions used in compressed sensing, such as the Bernoulli-Gaussian distribution and distributions, that decay like exp (-O(|x|p)) for 1 < p < 2. We further explore the implications of...

Deterministic construction of binary, bipolar, and ternary compressed sensing matrices

, Article IEEE Transactions on Information Theory ; Volume 57, Issue 4 , April , 2011 , Pages 2360-2370 ; 00189448 (ISSN) Amini, A ; Marvasti, F ; Sharif University of Technology

2011

Abstract

In this paper, we establish the connection between the Orthogonal Optical Codes (OOC) and binary compressed sensing matrices. We also introduce deterministic bipolar m × n RIP fulfilling ± 1 matrices of order k such that m ≤ script O sign (k(log2 n) log2 k/ln log2 k). The columns of these matrices are binary BCH code vectors where the zeros are replaced by -1. Since the RIP is established by means of coherence, the simple greedy algorithms such as Matching Pursuit are able to recover the sparse solution from the noiseless samples. Due to the cyclic property of the BCH codes, we show that the FFT algorithm can be employed in the reconstruction methods to considerably reduce the computational...

Multi-level authorisation model and framework for distributed semantic-aware environments

, Article IET Information Security ; Volume 4, Issue 4 , 2010 , Pages 301-321 ; 17518709 (ISSN) Amini, M ; Jalili, R ; Sharif University of Technology

2010

Abstract

Semantic technology is widely used in distributed computational environments to increase interoperability and machine readability of information through giving semantics to the underlying information and resources. Semantic-awareness, distribution and interoperability of new generation of distributed systems demand an authorisation model and framework that satisfies essential authorisation requirements of such environments. In this study, the authors propose an authorisation model and framework based on multi-security-domain architecture for distributed semantic-aware environments. The proposed framework is founded based on the MA(DL)2 logic, which enables policy specification and inference...

A new framework to train autoencoders through non-smooth regularization

, Article IEEE Transactions on Signal Processing ; Volume 67, Issue 7 , 2019 , Pages 1860-1874 ; 1053587X (ISSN) Amini, S ; Ghaemmaghami, S ; Sharif University of Technology

Institute of Electrical and Electronics Engineers Inc 2019

Abstract

Deep structures consisting of many layers of nonlinearities have a high potential of expressing complex relations if properly initialized. Autoencoders play a complementary role in training a deep structure by initializing each layer in a greedy unsupervised manner. Due to the high capacity presented by autoencoders, these structures need to be regularized. While mathematical regularizers (based on weight decay, sparsity, etc.) and structural ones (by way of, e.g., denoising and dropout) have been well studied in the literature, quite a few papers have addressed the problem of training autoencoder with non-smooth regularization. In this paper, we address the problem of training autoencoder...

Lowering mutual coherence between receptive fields in convolutional neural networks

, Article Electronics Letters ; Volume 55, Issue 6 , 2019 , Pages 325-327 ; 00135194 (ISSN) Amini, S ; Ghaemmaghami, S ; Sharif University of Technology

Institution of Engineering and Technology 2019

Abstract

It has been shown that more accurate signal recovery can be achieved with low-coherence dictionaries in sparse signal processing. In this Letter, the authors extend the low-coherence attribute to receptive fields in convolutional neural networks. A new constrained formulation to train low-coherence convolutional neural network is presented and an efficient algorithm is proposed to train the network. The resulting formulation produces a direct link between the receptive fields of a layer through training procedure that can be used to extract more informative representations from the subsequent layers. Simulation results over three benchmark datasets confirm superiority of the proposed...

Towards improving robustness of deep neural networks to adversarial perturbations

, Article IEEE Transactions on Multimedia ; Volume 22, Issue 7 , 2020 , Pages 1889-1903 Amini, S ; Ghaemmaghami, S ; Sharif University of Technology

Institute of Electrical and Electronics Engineers Inc 2020

Abstract

Deep neural networks have presented superlative performance in many machine learning based perception and recognition tasks, where they have even outperformed human precision in some applications. However, it has been found that human perception system is much more robust to adversarial perturbation, as compared to these artificial networks. It has been shown that a deep architecture with a lower Lipschitz constant can generalize better and tolerate higher level of adversarial perturbation. Smooth regularization has been proposed to control the Lipschitz constant of a deep architecture and in this work, we show how a deep convolutional neural network (CNN), based on non-smooth regularization...

Calculus for composite authorities' policy derivation in shared domains of pervasive computing environments

, Article 11th International Conference on Computer and Information Technology, ICCIT 2008, Khulna, 25 December 2008 through 27 December 2008 ; March , 2008 , Pages 21-28 ; 9781424421367 (ISBN) Amini, M ; Jalili, R ; Sharif University of Technology

2008

Abstract

The decentralized security management in a pervasive computing environment' requires apportioning the environment into several security domains. In each security domain' an administrator (we call it authority) is responsible for specifying the security policies of the domain. Overlapping of security domains results in the requirement of cooperative security management in the shared/ overlapping domains. To satisfy this requirement' we propose an abstract security model' as well as its supplementary calculus of composite authorities. The security model is based on deontic logic and is independent of the domains' heterogeneity. The model's policy language (we call it MASL) enables multiple...

Convergence analysis of an iterative method for the reconstruction of multi-band signals from their uniform and periodic nonuniform samples

, Article Sampling Theory in Signal and Image Processing ; Volume 7, Issue 2 , 1 May , 2008 , Pages 113-129 ; 15306429 (ISSN) Amini, A ; Marvasti, F ; Sharif University of Technology

2008

Abstract

One of the proposed methods for recovery of a band-limited signal from its samples, whether uniform or nonuniform, is the so-called Frame Method. In this method the original signal is reconstructed by iterative use of sampling-filtering blocks. Convergence of this method for linear invertible operators has been previously proved. In this paper we show that this method for non-invertible periodic nonuniform samplings as well as non-invertible uniform samples of bandpass (or multi-band) signals will lead to the pseudo-inverse solution. Convergence conditions in case of additive noise will also be discussed. © 2008 Sampling Publishing

Towards robust visual transformer networks via k-sparse attention

, Article 47th IEEE International Conference on Acoustics, Speech, and Signal Processing, ICASSP 2022, 23 May 2022 through 27 May 2022 ; Volume 2022-May , 2022 , Pages 4053-4057 ; 15206149 (ISSN); 9781665405409 (ISBN) Amini, S ; Ghaemmaghami, S ; Sharif University of Technology

Institute of Electrical and Electronics Engineers Inc 2022

Abstract

Transformer networks, originally developed in the community of machine translation to eliminate sequential nature of recurrent neural networks, have shown impressive results in other natural language processing and machine vision tasks. Self-attention is the core module behind visual transformers which globally mixes the image information. This module drastically reduces the intrinsic inductive bias imposed by CNNs, such as locality, while encountering insufficient robustness against some adversarial attacks. In this paper we introduce K-sparse attention to preserve low inductive bias, while robustifying transformers against adversarial attacks. We show that standard transformers attend...