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Machine learning insights into PM2.5 changes during COVID-19 lockdown: LSTM and RF analysis in Mashhad
, Article Environmental Monitoring and Assessment ; Volume 196, Issue 5 , 2024 ; 01676369 (ISSN) ; Mohammadi, M ; Mohammadi, M ; Saloglu, D ; Sheikholeslami, R ; Sharif University of Technology
2024
Abstract
This study seeks to investigate the impact of COVID-19 lockdown measures on air quality in the city of Mashhad employing two strategies. We initiated our research using basic statistical methods such as paired sample t-tests to compare hourly PM2.5 data in two scenarios: before and during quarantine, and pre- and post-lockdown. This initial analysis provided a broad understanding of potential changes in air quality. Notably, a low reduction of 2.40% in PM2.5 was recorded when compared to air quality prior to the lockdown period. This finding highlights the wide range of factors that impact the levels of particulate matter in urban settings, with the transportation sector often being widely...
A rapid and sensitive HPLC-fluorescence method for determination of mirtazapine and its two major metabolites in human plasma
, Article Iranian Journal of Pharmaceutical Research ; Volume 13, Issue 3 , Summer 2014 , Pages 853-862 ; Giorgi, M ; Sheikholeslami, B ; Hedayati, M ; Rouini, M. R ; Sharif University of Technology
Summer 2014
Abstract
A rapid and sensitive HPLC method has been developed for the quantification of mirtazapine (MRZ), a noradrenergic and specific serotonergic inhibitor antidepressant (NaSSA) and its two major metabolites N-desmethyl mirtazapine (NDM) and 8-hydroxymirtazapine (8-OHM) in human plasma. The separation was achieved using Chromolith C18 column and a mobile phase of acetonitrile: phosphate buffer (pH = 3, 20:80, v/v) in isocratic mode at a flow rate of 2 mL/min. A fluorescence detector was set at 290 and 350 nm for excitation and emission, respectively. Zolpidem was used as the internal standard. Liquid-liquid extraction was applied for sample clean up. All analytes were eluted in less than 5...
Assessing chlorophyll-a variations in caspian sea during the covid-19 pandemic
, Article Bulletin of Environmental Contamination and Toxicology ; Volume 113, Issue 1 , 2024 ; 00074861 (ISSN) ; Ghorbani, P ; Sharif University of Technology
2024
Abstract
The COVID-19 pandemic’s disruptions to human activities prompted serious environmental changes. Here, we assessed the variations in coastal water quality along the Caspian Sea, with a focus on the Iranian coastline, during the lockdown. Utilizing Chlorophyll-a data from MODIS-AQUA satellite from 2015 to 2023 and Singular Spectrum Analysis for temporal trends, we found a 22% Chlorophyll-a concentration decrease along the coast, from 3.2 to 2.5 mg/m³. Additionally, using a deep learning algorithm known as Long Short-Term Memory Networks, we found that, in the absence of lockdown, the Chlorophyll-a concentration would have been 20% higher during the 2020–2023 period. Furthermore, our spatial...
Global patterns and key drivers of stream nitrogen concentration: A machine learning approach
, Article Science of the Total Environment ; Volume 868 , 2023 ; 00489697 (ISSN) ; Hall, J. W ; Sharif University of Technology
Elsevier B.V
2023
Abstract
Anthropogenic loading of nitrogen to river systems can pose serious health hazards and create critical environmental threats. Quantification of the magnitude and impact of freshwater nitrogen requires identifying key controls of nitrogen dynamics and analyzing both the past and present patterns of nitrogen flows. To tackle this challenge, we adopted a machine learning (ML) approach and built an ML-driven representation that captures spatiotemporal variability in nitrogen concentrations at global scale. Our model uses random forests to regress a large sample of monthly measured stream nitrogen concentrations onto a set of 17 predictors with a spatial resolution of 0.5-degree over the...
Developing a New Framework for Assessing the Impact of Data Uncertainty on Water Quality Index based on Multivariate Analysis
, M.Sc. Thesis Sharif University of Technology ; Sheikholeslami, Razi (Supervisor)
Abstract
Over the past several decades, human activities have resulted in a significant increase in surface and ground water pollution. Human activities have caused significant pollution of surface and groundwater, with pollutants like nitrates, phosphorus, heavy metals, toxins, and chemical fertilizers degrading water quality. In order to control pollution and reduce the concentration of pollutants in water, it is necessary to use appropriate numerical criteria to evaluate and manage the quality of water resources. The water quality index, as a scoring method for investigating the combined effects of independent parameters on overall water quality, is a widely-used metric for measuring the quality...
Evaluating The Efficiency of Machine Learning Methods for Variance-Based Sensitivity Analysis in Hydrological Models
, M.Sc. Thesis Sharif University of Technology ; Sheikholeslami, Razi (Supervisor)
Abstract
It is inevitable to simulate the phenomena that govern nature to make decisions and policies on water and environmental issues. Therefore, researchers have tried to make a good prediction of water's quantitative and qualitative status by using modeling and computer processing power. One of the primary and essential issues in modeling is using sensitivity analysis techniques. Using this knowledge, much information will be obtained on how to influence the model's output regarding various factors such as parameters, input data, and initial and boundary conditions. Global sensitivity analysis based on variance as one of the most well-known and, at the same time, the most widely used sensitivity...
Seismic Demand in Diaphragms and Collectors
, M.Sc. Thesis Sharif University of Technology ; Maleki, Shervin (Supervisor)
Abstract
This study investigates the seismic demand in diaphragms, chords and collectors in typical floor systems used in steel structures. These systems include joist-block slabs, open web steel joists, and composite steel decks. The lateral load resisting systems considered were Special Concentrically Braced Frames (SCBF) and Special Moment Frames (SMF) of varying heights. For each system, the influence of using shear connectors for perimeter beams, joist orientation, geometric configuration, and number of stories on lateral force transfer was examined. Nonlinear static and time history analyses were conducted on selected models. Key findings are as follows:
• In joist slab system without shear...
• In joist slab system without shear...
Machine Learning Analysis of Phosphorus Dynamics in Surface Waters Across Diverse Climate Zones
,
M.Sc. Thesis
Sharif University of Technology
;
Sheikholeslami, Razi
(Supervisor)
Abstract
Water quality is a fundamental pillar of public health, sustainable development, and food security, and monitoring pollutants such as total phosphorus (TP) plays a crucial role in the effective management of surface water resources. Phosphorus is an essential element for agricultural production; however, its loss from soil to aquatic systems can lead to environmental issues such as eutrophication, biodiversity loss, and degradation of water quality. Although monitoring TP concentrations is vital for effective water quality management, many countries face a lack of sufficient and consistent data. Numerical models, particularly data-driven approaches based on machine learning, can help bridge...
Developing A Machine Learning Framework for Predicting Fine Dust in the Lake Urmia Basin
, M.Sc. Thesis Sharif University of Technology ; Sheikholeslami, Razi (Supervisor)
Abstract
In recent decades, the unprecedented decline of water resources has turned Lake Urmia into one of Iran’s most critical environmental hotspots. The expansion of the lake’s dried bed has intensified the occurrence of salt dust storms, leading to serious consequences for public health, agriculture, the local economy, and ecological sustainability across the region. The main objective of this study was to develop a data-driven model to predict PM₁₀ concentrations over the Lake Urmia watershed using advanced machine learning algorithms. To achieve this, a comprehensive dataset was compiled, including meteorological variables, land cover types, remote sensing indices such as Aerosol Optical Depth...
Self-assembly of tryptophan-capped gold nanoparticles onto DNA network template
, Article Journal of Dispersion Science and Technology ; Volume 30, Issue 2 , 2009 , Pages 254-258 ; 01932691 (ISSN) ; Vosoughi, M ; Alemsadeh, I ; Sharif University of Technology
2009
Abstract
In this study, a simple route to the formation of DNA-gold complex has been reported, using immobilized DNA as a template. The nanoporous gold films have been prepared by the electrostatic self assembly of gold nanoparticles capped with tryptophan. Tryptophan would improve surface properties of gold nanoparticles for strongly attaching to DNA. Fourier transform infrared spectroscopy confirmed that gold nanoparticles have been capped by tryptophan. Also measured zeta potential shows that there are positive charges on the surface of gold nanoparticles. Investigations by atomic force microscopy substantially confirm that tryptophan-capped gold nanoparticles can be bonded to DNA template...
Fabrication of metal nanowires based on self assembly of tryptophan-capped gold nanoparticle onto DNA network template
, Article International Journal of Nanotechnology ; Volume 6, Issue 10-11 , 2009 , Pages 1041-1049 ; 14757435 (ISSN) ; Vossoughi, M ; Alemzadeh, I ; Sharif University of Technology
2009
Abstract
In this study, synthesis of conductive metal nanowires by using aligned and immobilised DNA strand on solid substrate is reported. The nanoporous gold film was prepared by electrostatic self assembly of gold nanoparticles capped with tryptophan. Tryptophan would improve surface properties of gold nanoparticles for strongly attaching to DNA. Fourier transform infrared (FTIR) spectroscopy confirmed that gold nanoparticles have been capped by tryptophan. Also measured zeta potential shows that there are positive charges on the surface of gold nanoparticles. Investigations by AFM observati on substantially confirm that tryptophan-capped gold nanoparticles can be bonded to DNA template...
Signed edge domination numbers in trees
, Article Ars Combinatoria ; Volume 93, Issue 1 OCT , 2009 , Pages 451-457 ; 03817032 (ISSN) ; Khodkar, A ; Sheikholeslami, M ; Sharif University of Technology
2009
Abstract
The closed neighborhood NG[e] of an edge e in a graph G is the set consisting of e and of all edges having a common endvertex with e. Let f be a function on E(G), the edge set of G, into the set {-1, 1}. If Σx∈N[e] f(x) ≥ 1 for each e ∈ E(G), then f is called a signed edge dominating function of G. The minimum of the values Σe∈E(G) f(e), taken over all signed edge dominating function f of G, is called the signed edge domination number of G and is denoted by γ′s(G). It has been conjectured that γ′s(T) ≥ 1 for every tree T. In this paper we prove that this conjecture is true and then classify all trees T with γ′s(T) = 1, 2 and 3
An upper bound for total domination subdivision numbers
, Article Ars Combinatoria ; Volume 102 , February , 2011 , Pages 321-331 ; 03817032 (ISSN) ; Khodkar, A ; Sheikholeslami, S. M ; Sharif University of Technology
2011
Abstract
A set S of vertices of a graph G = (V, E) without isolated vertex is a total dominating set if every vertex of V(G) is adjacent to some vertex in S. The total domination number γt(G) is the minimum cardinality of a total dominating set of G. The total domination subdivision number sd γt (G) is the minimum number of edges that must be subdivided (each edge in G can be subdivided at most once) in order to increase the total domination number. In this paper we first prove that sdγt(G) < n -δ + 2 for every simple connected graph G of order n ≥ 3. We also classify all simple connected graphs G with sdγt (G) = n -δ+ 2,n-δ + 1, and n-δ
Optimal probabilistic initial and target channel selection for spectrum handoff in cognitive radio networks
, Article IEEE Transactions on Wireless Communications ; Volume 14, Issue 1 , 2015 , Pages 570-584 ; 15361276 (ISSN) ; Nasiri Kenari, M ; Ashtiani, F ; Sharif University of Technology
2015
Abstract
Spectrum mobility in cognitive radio networks not only enables the secondary users to guarantee the desired QoS of the primary users but also grants an efficient exploitation of the available spectrum holes in the network. In this paper, we propose a probabilistic approach in determining the initial and target channels for the handoff procedure in a single secondary user network. To characterize the network, a queuing theoretical framework is introduced, and 'stay' and 'change' handoff policies are both addressed. The performance of the secondary user in terms of average sojourn and extended service times for secondary connections is analyzed, and convex optimization problems with the...
An improved upper bound for signed edge domination numbers in graphs
, Article Utilitas Mathematica ; Volume 78 , 2009 , Pages 121-128 ; 03153681 (ISSN) ; Khodkar, A ; Sheikholeslami, S. M ; Sharif University of Technology
2009
Abstract
The closed neighborhood N G[e] of an edge e in a graph G is the set consisting of e and of all edges having a common end-vertex with e. Let f be a function on E(G), the edge set of G, into the set {-1, 1}. If σ xεN[e] f(x) ≥ 1 for each e ε E(G), Then f is called a signed edge dominating function of G. The minimum of the values of σ xεE(G) f(x), taken over every signed edge dominating function f of G, is called the signed edge domination number of G and is denoted by γ′ s(G). It has been conjectured that γ′ s(G) ≥ n - 1 for every simple graph G of order n. In this paper we prove that this conjecture is true for Eulerian simple graphs, simple graphs with all vertices of odd degree and regular...
Connected domination subdivision numbers of graphs
, Article Utilitas Mathematica ; Volume 77 , 2008 , Pages 101-111 ; 03153681 (ISSN) ; Karami, H ; Sheikholeslami, S. M ; Sharif University of Technology
2008
Abstract
A set S of vertices of a graph G = (V, E) is a connected dominating set if every vertex of V(G) S is adjacent to some vertex in S and the induced subgraph G[S] is connected. The connected domination number γc (G) is the minimum cardinality of a connected dominating set of G. The connected domination subdivision number sdγc(G) is the minimum number of edges that must be subdivided (each edge in G can be subdivided at most once) in order to increase the connected domination number. In this paper first we establish upper bounds on the connected domination subdivision number in terms of the order n of G or of its edge connectivity number K'(G). We also prove that γc(G) + sdγc(G) ≤ n - 1 with...
Total domination and total domination subdivision numbers
, Article Australasian Journal of Combinatorics ; Volume 38 , 2007 , Pages 229-235 ; 10344942 (ISSN) ; Karami, H ; Sheikholeslami, S. M ; Sharif University of Technology
2007
Abstract
A set S of vertices of a graph G = (V, E) without isolated vertex is a total dominating set if every vertex of V(G) is adjacent to some vertex in S.The total domination number γ<(G) is the minimum cardinality of a total dominating set of G. The total domination subdivision number sdγt(G) is the minimum number of edges that must be subdivided (each edge in G can be subdivided at most once) in order to increase the total domination number. We show that sdγt(G) ≤ n - γt(G) + 1 for any graph G of order n ≥ 3 and that sdγt(G) < n-γt(G) except if G ≃ P3, C3, K4, P6 or C6
Soft decision m-pulse CFAR detection in weibull clutter
, Article IEEE 2007 Radar Conference, Waltham, MA, 17 April 2007 through 20 April 2007 ; 2007 , Pages 487-490 ; 1424402840 (ISBN); 9781424402847 (ISBN) ; Norouzi, Y ; Nayebi, M. M ; Sharif University of Technology
2007
Abstract
CFAR detector is an essential component in any radar system. This component ensures that the system may not be overloaded by false targets. In the past it was common to model the interfering signal (clutter) in a radar system with a Rayleigh distribution. But as a progress in the radar systems, nowadays the Rayleigh model is insufficient, therefore some other models such as Weibull and lognormal are proposed and CFAR detectors for these models are developed through the papers. But majority of these proposed CFAR detectors are derived for single pulse operation. When more than one pulse exists, it is proposed to use binary integrator to improve the performance. It is mentioned through...
Paired-domination number of a graph and its complement
, Article Discrete Mathematics ; Volume 308, Issue 24 , 2008 , Pages 6601-6605 ; 0012365X (ISSN) ; Karami, H ; Sheikholeslami, S. M ; Sharif University of Technology
2008
Abstract
A paired-dominating set of a graph G = (V, E) with no isolated vertex is a dominating set of vertices inducing a graph with a perfect matching. The paired-domination number of G, denoted by γp r (G), is the minimum cardinality of a paired-dominating set of G. We consider graphs of order n ≥ 6, minimum degree δ such that G and over(G, -) do not have an isolated vertex and we prove that. -if γp r (G) > 4 and γp r (over(G, -)) > 4, then γp r (G) + γp r (over(G, -)) ≤ 3 + min {δ (G), δ (over(G, -))}. -if δ (G) ≥ 2 and δ (over(G, -)) ≥ 2, then γp r (G) + γp r (over(G, -)) ≤ frac(2 n, 3) + 4 and γp r (G) + γp r (over(G, -)) ≤ frac(2 n, 3) + 2 if moreover n ≥ 21. © 2007 Elsevier B.V. All rights...
Total domination and total domination subdivision number of a graph and its complement
, Article Discrete Mathematics ; Volume 308, Issue 17 , 6 September , 2008 , Pages 4018-4023 ; 0012365X (ISSN) ; Karami, H ; Sheikholeslami, S. M ; Sharif University of Technology
2008
Abstract
A set S of vertices of a graph G = (V, E) with no isolated vertex is a total dominating set if every vertex of V (G) is adjacent to some vertex in S. The total domination numberγt (G) is the minimum cardinality of a total dominating set of G. The total domination subdivision numbersdγt (G) is the minimum number of edges that must be subdivided in order to increase the total domination number. We consider graphs of order n ≥ 4, minimum degree δ and maximum degree Δ. We prove that if each component of G and over(G, -) has order at least 3 and G, over(G, -) ≠ C5, then γt (G) + γt (over(G, -)) ≤ frac(2 n, 3) + 2 and if each component of G and over(G, -) has order at least 2 and at least one...