Are the magnitude and frequency of floods increasing in Iran due to climate change? implications from a 50-year analysis

, Article Hydrological Sciences Journal ; Volume 68, Issue 15 , 2023 , Pages 2243-2261 ; 02626667 (ISSN) Bayat Afshary, N ; Danesh Yazdi, M ; Sharif University of Technology

Taylor and Francis Ltd 2023

Abstract

The correlation between extreme precipitation and flood magnitude is still poorly understood because of the complex mechanisms controlling flood generation. In this study, we used 50 years of precipitation and streamflow data across Iran to analyse the spatial distribution, slope, and significance of long-term trends in extreme precipitation compared to the spatial distribution of long-term trends for flood magnitude and frequency. Despite the decreasing trend of extreme precipitation in 60% of Iran’s sub-basins, the flood magnitude showed an increasing trend. In particular, the number of flooding days with a return period of 25~50 years and >50 years in 2010s has increased by 1.3 and 2.2...

An Optical Sensor Based on Manganese Oxide Nanosheets Oxidation Activity for Detection of Bisulfite in Food Samples

, M.Sc. Thesis Sharif University of Technology Bayat Afshary, Farbod (Author) ; Bagheri, Habib (Supervisor)

Abstract

Bisulfite is a food additive with preservative and antioxidant properties; however, excessive use can severely damage nutritional compounds in food, reducing nutritional value. Moreover, it can lead to the development of sensitivities, asthma, localized heart anemia, and lung cancer. Therefore, it is essential to establish a simple, innovative, fast, and reliable method for bisulfite identification in foodstuffs. In this research, a novel fluorescence sensor based on manganese oxide nanosheets and carbon dots was designed for bisulfite detection in food samples. Initially, manganese oxide nanosheets were synthesized via a bottom-up approach, and carbon dots were produced using a hydrothermal...

Exploring the Impact of Vegetation Type and Plant Growth Cycle on the Evapotranspiration Storage Selection Function Using Particle Tracking Approach

, M.Sc. Thesis Sharif University of Technology Bayat Afshary, Nooshdokht (Author) ; Danesh Yazdi, Mohammad (Supervisor)

Abstract

StorAge selection (SAS) functions describe the mechanism by which water particles with different ages exit a hydrological system through outfluxes such as streamflow and evapotranspiration (ET). The shape of the ET SAS functions affects the storage residence time distributions, ET travel time distributions, and discharge travel time distributions that control the hydrochemical dynamics of water. They also carry fundamental information to understand the response behavior of the system, and are affected by processes such as precipitation, outflow, ET, as well as the physical properties of the system. To better understand the shape of these functions, other important factors such as the type...

A method for automatic tuning the memristance of memristive devices with the capacity of applying to memristive memories

, Article 2012 International Conference on Computer Systems and Industrial Informatics, ICCSII 2012, 18 December 2012 through 20 December 2012 ; December , 2012 ; 9781467351577 (ISBN) Merrikh Bayat, F ; Merrikh Bayat, F ; Mirebrahimi, N ; Sharif University of Technology

2012

Abstract

Memristor is the fourth fundamental passive circuit element which has potential applications in development of analog memristive memories, neuroscience, and brain simulation. In all of these applications the memristance of the device should be adjusted to the desired value, which is currently performed by trial and error. The aim of this paper is to propose a new method and develop a circuit for automatic adjustment of the memristance of memristive devices. The proposed method is based on the sliding mode control and numerical simulations show that it can be used for tuning the memristance of such devices with a high accuracy

Silver nanoparticles supported on silica-coated ferrite as magnetic and reusable catalysts for oxidant-free alcohol dehydrogenation

, Article RSC Advances ; Volume 5, Issue 29 , Jan , 2015 , Pages 22503-22509 ; 20462069 (ISSN) Bayat, A ; Shakourian Fard, M ; Ehyaei, N ; Mahmoodi Hashemi, M ; Sharif University of Technology

Royal Society of Chemistry 2015

Abstract

Silver (0) nanoparticles supported on silica-coated ferrite were synthesized to be used as an efficient and recyclable heterogeneous catalyst for oxidant-free dehydrogenation of alcohols to the corresponding carbonyl compounds. The catalyst can be easily recovered and reused for 8 reaction cycles without considerable loss of activity. The facile recovery of the catalyst is carried out by applying an external magnetic device. The catalyst was fully characterized by the techniques of TEM, SEM, XRD, EDS, ICP-AES, and VSM. This journal is

Silver nanoparticles immobilized onto poly(4-vinylpyridine)-functionalized magnetic nanoparticles: a robust magnetically recyclable catalyst for oxidant-free alcohol dehydrogenation

, Article Applied Organometallic Chemistry ; Volume 32, Issue 2 , February , 2018 ; 02682605 (ISSN) Bayat, A ; Shakourian Fard, M ; Talebloo, N ; Mahmoodi Hashemi, M ; Sharif University of Technology

John Wiley and Sons Ltd 2018

Abstract

A heterogeneous and recyclable catalyst with a high loading of silver nanoparticles was synthesized via the silver nanoparticles being supported onto the surface of magnetic nanoparticles coated with poly(4-vinylpyridine). The synthesized catalyst was used in the dehydrogenation of alcohols to corresponding carbonyl compounds. A broad diversity of alcohols was converted into their corresponding carbonyl compounds in excellent yields. The catalyst was easily recovered by applying an external magnetic field and reused for seven reaction cycles without considerable loss of activity. The catalyst was fully characterized using various techniques. Copyright © 2017 John Wiley & Sons, Ltd

The neuro-fuzzy computing system with the capacity of implementation on a memristor crossbar and optimization-free hardware training

, Article IEEE Transactions on Fuzzy Systems ; Vol. 22, Issue. 5 , 2014 , Pages 1272-1287 ; ISSN: 10636706 Merrikh-Bayat, F ; Merrikh-Bayat, F ; Shouraki, S. B ; Sharif University of Technology

2014

Abstract

In this paper, first we present a new explanation for the relationship between logical circuits and artificial neural networks, logical circuits and fuzzy logic, and artificial neural networks and fuzzy inference systems. This shows us that neural networks are working in the same way as logical circuits when the connection between them is through the fuzzy logic. However, themain difference between them is that logical circuits can be constructed without using any kind of optimization-based learning methods. Based on these results, we propose a new neuro-fuzzy computing system. As verified by simulation results, it can effectively be implemented on the memristor crossbar structure and...

Memristive fuzzy edge detector

, Article Journal of Real-Time Image Processing ; Vol. 9, issue. 3 , September , 2014 , pp. 479-489 ; Online ISSN: 1861-8219 Merrikh-Bayat, F ; Bagheri Shouraki, S ; Merrikh-Bayat, F ; Sharif University of Technology

2014

Abstract

Fuzzy inference systems always suffer from the lack of efficient structures or platforms for their hardware implementation. In this paper, we tried to overcome this difficulty by proposing a new method for the implementation of the fuzzy rule-based inference systems. To achieve this goal, we have designed a multi-layer neuro-fuzzy computing system based on the memristor crossbar structure by introducing a new concept called the fuzzy minterm. Although many applications can be realized through the use of our proposed system, in this study we only show how the fuzzy XOR function can be constructed and how it can be used to extract edges from grayscale images. One main advantage of our...

Memristor crossbar-based hardware implementation of fuzzy membership functions

, Article Proceedings - 2011 8th International Conference on Fuzzy Systems and Knowledge Discovery, FSKD 2011, 26 July 2011 through 28 July 2011 ; Volume 1 , July , 2011 , Pages 645-649 ; 9781612841816 (ISBN) Merrikh Bayat, F ; Shouraki, S. B ; Merrikh Bayat, F ; Sharif University of Technology

2011

Abstract

In May 1, 2008, researchers at Hewlett Packard (HP) announced the first physical realization of a fundamental circuit element called memristor that attracted so much interest worldwide. This newly found element can easily be combined with crossbar interconnect technology which this new structure has opened a new field in designing configurable or programmable electronic systems. These systems in return can have applications in signal processing and artificial intelligence. In this paper, based on the simple memristor crossbar structure, we propose new and simple circuits for hardware implementation of fuzzy membership functions. In our proposed circuits, these fuzzy membership functions can...

Zygomatic bone registration based on a modified student's mixture model method

, Article 26th National and 4th International Iranian Conference on Biomedical Engineering, ICBME 2019, 27 November 2019 through 28 November 2019 ; 2019 , Pages 88-92 ; 9781728156637 (ISBN) Noori, S. M. R ; Mobaraki, M ; Ahmadian, A ; Bayat, M ; Bahrami, N ; Sharif University of Technology

Institute of Electrical and Electronics Engineers Inc 2019

Abstract

Point Set Registration (PSR) of anatomic parts is used in different fields such as Patient Specific Implant (PSI) design in Computer Assisted Surgery (CAS) procedure. We designed a modified rigid PSR method based on student's-t mixture model. The proposed method is compared with Coherent Point Drift (CPD) registration method. Higher convergence speed and the lower error value are the advantages of the suggested algorithm in compare with CPD. In our method, the number of iterations decreases by about 69%, and the final error improvement was about 7% in comparison with CPD. The robustness of the proposed algorithm makes it beneficial to be used in the procedure of designing PSI in both...

On social-aware content caching for D2D-enabled cellular networks with matching theory

, Article IEEE Internet of Things Journal ; 2017 ; 23274662 (ISSN) Li, J ; Liu, M ; Lu, J ; Shu, F ; Zhang, Y ; Bayat, S ; Jayakody, D. N. K ; Sharif University of Technology

2017

Abstract

In this paper, the problem of content caching in 5G cellular networks relying on social-aware device-to-device (D2D) communications is investigated. Our focus is on how to efficiently select important users (IUs) and how to allocate content files to the storage of these selected IUs to form a distributed caching system. We aim at proposing a novel approach for minimizing the downloading latency and maximizing the social welfare simultaneously. In particular, we first model the problem of maximizing the social welfare as a many-to-one matching game based on the social property of mobile users. We study this game by exploiting users’ social properties to generate the utility functions of the...

On social-aware content caching for d2d-enabled cellular networks with matching theory

, Article IEEE Internet of Things Journal ; Volume 6, Issue 1 , 2019 , Pages 297-310 ; 23274662 (ISSN) Li, J ; Liu, M ; Lu, J ; Shu, F ; Zhang, Y ; Bayat, S ; Jayakody, D. N. K ; Sharif University of Technology

Institute of Electrical and Electronics Engineers Inc 2019

Abstract

In this paper, the problem of content caching in 5G cellular networks relying on social-aware device-to-device communications (DTD) is investigated. Our focus is on how to efficiently select important users (IUs) and how to allocate content files to the storage of these selected IUs to form a distributed caching system. We aim at proposing a novel approach for minimizing the downloading latency and maximizing the social welfare simultaneously. In particular, we first model the problem of maximizing the social welfare as a many-to-one matching game based on the social property of mobile users. We study this game by exploiting users' social properties to generate the utility functions of the...

Investigation of the scavenging mechanism of tyrosyl radical by hydroxybenzohydroxamic acid derivatives: A DFT study

, Article Computational and Theoretical Chemistry ; Volume 1018 , 2013 , Pages 35-44 ; 2210271X (ISSN) Bayat, A ; Fattahi, A ; Sharif University of Technology

2013

Abstract

The free radical scavenging activity of a series of hydroxybenzohydroxamic acid derivatives have been studied in gas phase, water and benzene environments, using the density functional theory. Different mechanisms of reactions have been considered: single electron transfer (SET), hydrogen atom transfer (HAT). Rate constants were determined to know if the radical scavenging activity of these compounds proceeds via an H-atom or an electron-transfer mechanism. Calculations showed that the presence of the adjacent hydroxyl groups on phenyl ring increases the radical stability through intramolecular hydrogen bonds. The calculated bond dissociation enthalpy (BDE) values for hydroxyl groups on...

A quantum chemical study on the OH radical quenching by natural antioxidant fisetin

, Article Journal of Physical Organic Chemistry ; Volume 30, Issue 11 , 2017 ; 08943230 (ISSN) Bayat, A ; Fattahi, A ; Sharif University of Technology

2017

Abstract

In this work, the antioxidant ability of fisetin was explored toward hydroxyl (•OH) radical in aqueous and lipid solution using density functional level of theory. Different reaction mechanisms have been studied: hydrogen atom transfer, single electron transfer followed by proton transfer, and radical adduct formation, and sequential proton loss electron transfer. Rate constants for all possible reaction sites have been calculated using conventional transition state theory in conjunction with the Collins-Kimball theory. Branching ratios for the different channels of reaction are reported for the first time. Results show that the reactivity of fisetin toward hydroxyl (•OH) radical takes place...

Influence of remote intramolecular hydrogen bonding on the acidity of hydroxy-1,4-benzoquinonederivatives: A DFT study

, Article Journal of Physical Organic Chemistry ; Volume 32, Issue 4 , 2019 ; 08943230 (ISSN) Bayat, A ; Fattahi, A ; Sharif University of Technology

John Wiley and Sons Ltd 2019

Abstract

In this study, the effects of the remote intramolecular hydrogen bonding on the acidity of hydroxy-1,4-benzoquinone derivatives have been investigated ab initio by employing density functional theory (DFT) methods. The computational studies were performed for both gas and solution (H 2 O, DMSO, and MeCN solutions) phases. Our results indicated that remote hydrogen bonding could play an important role in increasing the acidity of hydroxy-1,4-benzoquinone. Noncovalent interaction reduced density gradient (NCI-RDG) methods were used to visualize the attractive and repulsive interactions in the studied acids and their conjugate bases. Natural bond orbital (NBO) analysis was performed to confirm...

An optimal hybrid nuclear norm regularization for matrix sensing with subspace prior information

, Article IEEE Access ; Volume 8 , 2020 , Pages 130937-130946 Bayat, S ; Daei, S ; Sharif University of Technology

Institute of Electrical and Electronics Engineers Inc 2020

Abstract

Matrix sensing refers to recovering a low-rank matrix from a few linear combinations of its entries. This problem naturally arises in many applications including recommendation systems, collaborative filtering, seismic data interpolation and wireless sensor networks. Recently, in these applications, it has been noted that exploiting additional subspace information might yield significant improvements in practical scenarios. This information is reflected by two subspaces forming angles with column and row spaces of the ground-truth matrix. Despite the importance of exploiting this information, there is limited theoretical guarantee for this feature. In this work, we aim to address this issue...

The free radical scavenging activity of lespedezacoumestan toward ˙OH radical: a quantum chemical and computational kinetics study

, Article Journal of Physical Organic Chemistry ; Volume 31, Issue 2 , February , 2018 ; 08943230 (ISSN) Bayat, A ; Fattahi, A ; Sharif University of Technology

John Wiley and Sons Ltd 2018

Abstract

The free radical activity of lespedezacoumestan was investigated toward hydroxyl (˙OH) radical in polar and nonpolar media using density functional theory. Four reaction mechanisms including radical adduct formation, hydrogen atom transfer, sequential single electron-proton transfer (SET-PT), and sequential proton loss electron transfer were considered. The rate constants and branching ratio for all possible sites of reaction were calculated and reported for the first time. According to the obtained results, lespedezacoumestan reacts faster with ˙OH radical in aqueous solution than in nonpolar media. Also, lespedezacoumestan is an excellent ˙OH radical scavenger regardless of the environment...

Transfer of d -level quantum states through spin chains by random swapping

, Article Physical Review A - Atomic, Molecular, and Optical Physics ; Volume 75, Issue 2 , 2007 ; 10502947 (ISSN) Bayat, A ; Karimipour, V ; Sharif University of Technology

2007

Abstract

We generalize an already proposed protocol for quantum state transfer to spin chains of arbitrary spin. An arbitrary unknown d -level state is transferred through a chain with rather good fidelity by the natural dynamics of the chain. We compare the performance of this protocol for various values of d. A by-product of our study is a much simpler method for picking up the state at the destination as compared with the one proposed previously. We also discuss entanglement distribution through such chains and show that the quality of entanglement transition increases with the number of levels d. © 2007 The American Physical Society

Separating radar signals from impulsive noise using atomic norm minimization

, Article IEEE Transactions on Circuits and Systems II: Express Briefs ; Volume 68, Issue 6 , 2021 , Pages 2212-2216 ; 15497747 (ISSN) Bayat, S ; Daei, S ; Sharif University of Technology

Institute of Electrical and Electronics Engineers Inc 2021

Abstract

We consider the problem of corrupted radar super-resolution, a generalization of compressed radar super-resolution in which one aims to recover the continuous-valued delay-Doppler pairs of moving objects from a collection of corrupted and noisy measurements. The received signal in this type consists of contributions from objects, outlier and noise. While this problem is ill-posed in general, tractable recovery is possible when both the number of objects and corrupted measurements are limited. In this brief, we propose an atomic norm optimization in order to find the delay-Doppler pairs and the outlier signal. The objective function of our optimization problem encourages both sparsity in the...

Thermal effects on quantum communication through spin chains

, Article Physical Review A - Atomic, Molecular, and Optical Physics ; Volume 71, Issue 4 , 2005 ; 10502947 (ISSN) Bayat, A ; Karimipour, V ; Sharif University of Technology

2005

Abstract

We study the effect of thermal fluctuations in a recently proposed protocol for transmission of unknown quantum states through quantum spin chains. We develop a low-temperature expansion for general spin chains. We then apply this formalism to study exactly thermal effects on short spin chains of four spins. We show that optimal times for extraction of output states are almost independent of the temperature, which lowers only the fidelity of the channel. Moreover we show that thermal effects are smaller in the antiferromagnetic chains than the ferromagnetic ones. © 2005 The American Physical Society