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On the spectrum of the forced matching number of graphs
, Article Australasian Journal of Combinatorics ; Volume 30 , 2004 , Pages 147-160 ; 10344942 (ISSN) ; Hatami, H ; Mahmoodian, E. S ; Sharif University of Technology
2004
Abstract
Let G be a graph that admits a perfect matching. A forcing set for a perfect matching M of G is a subset S of M, such that S is contained in no other perfect matching of G. This notion originally arose in chemistry in the study of molecular resonance structures. Similar concepts have been studied for block designs and graph colorings under the name defining set, and for Latin squares under the name critical set. Recently several papers have appeared on the study of forcing sets for other graph theoretic concepts such as dominating sets, orientations, and geodetics. Whilst there has been some study of forcing sets of matchings of hexagonal systems in the context of chemistry, only a few other...
Experimental Study of Lightweight and Normal-Weight Concrete under Impact Loads: The Influence of Prestressing and Fiber Reinforcement
, Ph.D. Dissertation Sharif University of Technology ; Rahimzadeh Rofooei, Fayaz (Supervisor)
Abstract
Given the increasing use of lightweight concrete in the construction industry, particularly in precast elements, evaluating its performance under dynamic loads such as impact is of high importance. This study presents an experimental and numerical investigation into the behavior of slabs made from lightweight and normal-weight concrete under low-velocity impact loads, and evaluates the effectiveness of two strengthening techniques: prestressing and the addition of steel fibers. In the experimental phase, fifteen concrete slabs with identical dimensions were designed and fabricated. The main variables included the concrete type (lightweight and normal-weight), the reinforcement method...
Optical Injection Phase-Locked Loop Application in Continuous-variable Quantum Key Distributions
, Ph.D. Dissertation Sharif University of Technology ; Bahrampour, Alireza (Supervisor)
Abstract
The primary objective of this thesis is to provide solutions addressing some security loopholes in continuous variables quantum key distribution protocols. The coherent detection method is utilized in this particular quantum key distribution scheme, which is a phase-sensitive detection. To measure in the quantum noise limit in the detection part, we need a local optical oscillator, which must possess a high intensity and a consistent phase correlation with the quantum signal. Therefore, reconstructing the emitter’s reference phase in the receiver’s detection system is considered as one of the most critical challenges in these protocols. In order to attain this goal, in the early versions of...
Using Information Beyond Text to Generate Language Embedding Vectors
, M.Sc. Thesis Sharif University of Technology ; Sameti, Hossein (Supervisor)
Abstract
In this thesis, we introduce a novel Artificial Intelligence (AI) system inspired by the philosophical and psychoanalytical concept of imagination as a ``Re-construction of Experiences". Our AI system is equipped with an imagination-inspired module that bridges the gap between textual inputs and other modalities, enriching the derived information based on previously learned experiences. A unique feature of our system is its ability to formulate independent perceptions of inputs. This leads to unique interpretations of a concept that may differ from human interpretations but are equally valid, a phenomenon we term as ``Interpretable Misunderstanding". We employ large-scale models,...
Design and Fabrication of Microfluidic System as Concentration Gradient Generator
, M.Sc. Thesis Sharif University of Technology ; Saadatmand, Maryam (Supervisor)
Abstract
According to today’s medicine progress, the need for improving the medical facilities have been increased. Within the human body, the biomolecules concentration gradient is regulating the cell functions. Biological processes such as immune response, wound healing, and cancer metastasis have been affected by the bimolecular concentration gradient. So understanding the cell behavior in the presence of a chemical gradient can improve the understanding from these biological processes, and also would help in medical researches. On the other hand, finding the appropriate dose of the drugs and in some cases finding the most effective drug is a clinical challenge that made a new field of research in...
Investigation of the Performance of Microbial Fuel Cell Based on Shewanella Bacteria with the Aim of Nanostructured Materials
, M.Sc. Thesis Sharif University of Technology ; Yaghmaei, Soheila (Supervisor) ; Sanaee, Zeinab (Co-Supervisor)
Abstract
The development of clean, renewable and alternative sources of fossil fuels has increased in recent years due to various factors such as environmental pollution, reduced fossil fuel resources and increased energy consumption. The application of microbial fuel cells is one of the clean energy production methods using renewable sources such as municipal sewage. The microbial fuel cell converts the chemical energy stored in organic materials into electrical energy and simultaneously purifies the sewage. Increasing current density and power density are the most important challenges for microbial fuel cells. In this study, the two biocatalysts of Shewanella Oneidensis MR1 and Escherichia coli...
Circular chromatic index of graphs of maximum degree 3
, Article Journal of Graph Theory ; Volume 49, Issue 4 , 2005 , Pages 325-335 ; 03649024 (ISSN) ; Ghandehari, M ; Ghandehari, M ; Hatami, H ; Tusserkani, R ; Zhu, X ; Sharif University of Technology
Wiley-Liss Inc
2005
Abstract
This paper proves that if G is a graph (parallel edges allowed) of maximum degree 3, then χc′(G) ≤ 11/3 provided that G does not contain H1 or H2 as a subgraph, where H1 and H2 are obtained by subdividing one edge of K23 (the graph with three parallel edges between two vertices) and K4, respectively. As χc′(H1) = χ c′(H2) = 4, our result implies that there is no graph G with 11/3 < χc′(G) < 4. It also implies that if G is a 2-edge connected cubic graph, then χc′(G) ≤ 11/3. © 2005 Wiley Periodicals, inc
Synthesis, Evaluation and Modification of Suitable Metal–Organic Frameworks (MOFS) for Desulfurization of Hydrocarbon Cuts
, M.Sc. Thesis Sharif University of Technology ; Khorashe, Farhad (Supervisor) ; Hajjar, Zeinab (Co-Supervisor) ; Soltanali, Saeed (Co-Supervisor)
Abstract
During fuel combustion, aromatic sulfur compounds in energy fuels convert into sulfur oxides, which cause major environmental problems such as acidic rain, global warming, and air pollution. Absorption desulfurization is one of the promising and economical methods to remove these sulfur compounds from fuels. Metal-organic frameworks (MOFs) are a class of nanoporous materials that are of interest for use as adsorbents due to their high specific surface area, unique surface adsorption properties, high adsorption capacity, tunable porosity, flexible dynamic behavior, and diversity in functional and metal groups. In this research, we first synthesized five metal-organic frameworks, namely...
Reduction of Sulfur Content of Model Feed by Oxidative Process in them Presence of Carbon Structures Based W-Mo Nanocatalysts
, Ph.D. Dissertation Sharif University of Technology ; Kazemini, Mohammad (Supervisor) ; Rashidi, Alimorad (Supervisor) ; Hajjar, Zeinab (Co-Supervisor)
Abstract
In this research, molybdenum and tungsten catalysts modified with cobalt and nickel on a carbon support have been synthesized and investigated in the oxidation desulfurization process. A model fuel was used to evaluate the synthesized catalysts. This model fuel was n-decane. dibenzothiophene was also used as a sulfur model. The synthesized catalysts were subjected to various analyzes such as XRD, FTIR, Raman, BET-BJH, NH3-TPD, TEM and ICP-OES for structural evaluation. On the other hand, synthetic parameters such as metal loading rate, molar or weight ratio of secondary metal (cobalt and nickel) to primary metal (molybdenum and tungsten) and molar ratio of citric acid to primary metal as...
NOx Reduction from the Exhaust Gas of Marine Diesel Engines Using Non-Thermal Plasma
, M.Sc. Thesis Sharif University of Technology ; Borghei, Mehdi (Supervisor) ; Hamzehlouyan, Tayebeh (Supervisor) ; Hajjar, Zeinab (Supervisor) ; Khani, Mohammad Reza (Supervisor)
Abstract
Environmental regulations with respect to the marine diesel emissions have become stricter during recent years, thereby imposing traffic limitations on Iranian ships preventing them to enter emission control areas. Nitrogen oxides (NOx), as one of most important air pollutants, have adverse impacts on public health and ecosystem, so as the ships are the primary source of NOx internationally, the after-treatment system finds more urge to be developed. In this study, a NOx reduction system using non-thermal plasma technology is studied in order to determine its application and efficiency for NOx removal from the exhaust gas of Iranian marine diesel engines. Meanwhile, important factors were...