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Characterisation and Preparation of Chitosan-nano Diamond Nanocomposite
, M.Sc. Thesis Sharif University of Technology ; Shojaei, Akbar (Supervisor)
Abstract
Chitosan is a biocompatible and biopolymer with unique characteristics. Nanodiamonds that are basically carbon based nanoparticle have excellent mechanical, thermal stability biocompatibility bahviors. Combination of these two materials helps to the advantage of all the desirable features of both material and compensate low mechanical properties and strength of chitosan. In this study, we examine the composition of different percentages of nanodiamonds in chitosan and effect of modification on properties of the nanocomposites. The thermal behaviour, swelling behaviour and water contact angle of different nanocomposites were analyzed. Finally, to determine the distribution of the...
Enhanced mechanical properties of chitosan/nanodiamond composites by improving interphase using thermal oxidation of nanodiamond
, Article Carbohydrate Polymers ; Volume 167 , 2017 , Pages 219-228 ; 01448617 (ISSN) ; Shojaei, A ; Sharif University of Technology
Elsevier Ltd
2017
Abstract
Polymer composite films based on chitosan (CS) and nanodimaond (ND) were prepared using solution casting method. ND with variable contents of carboxylic functional group was prepared using thermal oxidation at temperature of 420 °C under air atmosphere at various durations of 1.5 and 4.5 h. The interfacial interaction between NDs and CS and morphological evolution of CS in presence of NDs were investigated by Fourier transform infrared (FTIR), differential scanning calorimeter (DSC) and X-ray diffraction (XRD) analyses. A significant improvement in tensile strength (∼85%) and tensile modulus (∼125%) of CS was achieved by oxidized ND (OND) obtained at higher oxidation time of 4.5 at low...
Gain and Phase Margins in a Class of Nonlinear Systems
, M.Sc. Thesis Sharif University of Technology ; Haeri, Mohammad (Supervisor)
Abstract
The stability of dynamic systems has long been discussed in the theory of control and many people and experts have researched in this field and important results have been obtained from their research. In the real world, systems stability is the premise of controlling their behavior. In fact, systems that are unstable will not be controllable without stability. Therefore, the stability of the systems is discussed and at the same time the control expectations of the system will be raised. The systems of the surrounding world behave nonlinearly; Therefore, their exact stability is not debatable with linear approaches and requires stronger mathematics and attention to specific behaviors of...
Modeling, estimation, and model predictive control for Covid-19 pandemic with finite security duration vaccine
, Article 30th International Conference on Electrical Engineering, ICEE 2022, 17 May 2022 through 19 May 2022 ; 2022 , Pages 78-83 ; 9781665480871 (ISBN) ; Baghbadorani, R. R ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2022
Abstract
Spreading Covid19 has significantly impacted humans' affairs worldwide, either economically or in a sanitary manner. Besides social distance and hospitalization, making and introducing different vaccines help us ameliorate infection and mortality rates. In this research, we use a nonlinear dynamic model for Covid19, with eight states named susceptible, exposed, infected, quarantined, hospitalized, recovered, deceased, and insusceptible populations. Also, we use social distancing, hospitalization, and vaccination rate as three control inputs. This research aims to stop the Covid-19 from spreading worldwide and minimize exposed, infected and deceased populations using model predictive control....
A ring oscillator-based PUF with enhanced challenge-response pairs
, Article Canadian Journal of Electrical and Computer Engineering ; Volume 39, Issue 2 , 2016 , Pages 174-180 ; 08408688 (ISSN) ; Mirzakuchaki, S ; Mohajeri, J ; Sharif University of Technology
IEEE Canada
2016
Abstract
Physical unclonable functions (PUFs) are powerful security primitives that provide cheap and secure solutions for security-related applications. Strong PUFs provide a large set of challenge-response pairs (CRPs) and are suitable for device authentication. Weak PUFs produce a small number of CRPs and can be used for key extraction. In this paper, we propose a novel method to enhance the CRP set of traditional ring oscillator-based PUFs (RO-PUFs). RO-PUFs are one of the most reliable types of PUFs and the best fit to implement on the field-programmable gate arrays. To the best of our knowledge, our method provides the maximum number of CRPs compared with the state of the art. In addition, the...
New scheduling algorithm for dynamic task and fault tolerant in heterogeneous grid systems using genetic algorithm
, Article Proceedings - 2010 3rd IEEE International Conference on Computer Science and Information Technology, ICCSIT 2010, 9 July 2010 through 11 July 2010 ; Volume 9 , July , 2010 , Pages 408-412 ; 9781424455386 (ISBN) ; Nejadkheirallah, M ; Motalleb, M ; Sharif University of Technology
2010
Abstract
In this paper with studying of all parameters in grid environment a new scheduling algorithm for independent task is introduced according to Genetic Algorithm. This algorithm can be more efficient and more dependable than similar previous algorithms. The simulated results and reasons for reaching to better makes pan and more efficiency in the grid environment. In the grids with high fault with high fault rate for fault tolerant is used from check point method that has more efficiency that other methods such as retry, migration and replication. This method maintains effective efficiency in these situations. So the servicing quality increases in various grid environments and also the average...
PUF-based solutions for secure communications in advanced metering infrastructure (AMI)
, Article International Journal of Communication Systems ; Volume 30, Issue 9 , 2017 ; 10745351 (ISSN) ; Mirzakuchaki, S ; Ameri, M. H ; Mohajeri, J ; Sharif University of Technology
John Wiley and Sons Ltd
2017
Abstract
Advanced metering infrastructure (AMI) provides 2-way communications between the utility and the smart meters. Developing authenticated key exchange (AKE) and broadcast authentication (BA) protocols is essential to provide secure communications in AMI. The security of all existing cryptographic protocols is based on the assumption that secret information is stored in the nonvolatile memories. In the AMI, the attackers can obtain some or all of the stored secret information from memories by a great variety of inexpensive and fast side-channel attacks. Thus, all existing AKE and BA protocols are no longer secure. In this paper, we investigate how to develop secure AKE and BA protocols in the...
On the security of YRL, an anonymous broadcast encryption scheme
, Article 8th International Symposium on Telecommunications, IST 2016, 27 September 2016 through 29 September 2016 ; 2017 , Pages 752-755 ; 9781509034345 (ISBN) ; Ameri, M. H ; Delavar, M ; Mohajeri, J ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2017
Abstract
Broadcast encryption is a novel concept for sending a special message to a subset of users. In broadcast encryption schemes, the distribution center broadcasts the message in encrypted form and expect that only the intended users be able to decrypt the message. This concept has several applications such as pay-per-service TVs. In this paper, we investigate one of the most recent broadcast encryption schemes and show that the introduced scheme does not provide the main requirement of broadcast encryption schemes. For this purpose, we demonstrate that all of the users, including authorized and unauthorized users, can decrypt the broadcasted encrypted message. © 2016 IEEE
Design of a Micromixer based on Cantilever Beam Displacement due to Piezoelectric Laminars
, M.Sc. Thesis Sharif University of Technology ; Ahmadian, Mohammad Taghi (Supervisor) ; Asghari, Mohsen (Co-Advisor)
Abstract
During the past decade, micromachining technology has become available to fabricate micron-sized mechanical parts. The miniaturization of almost all types of devices and systems is arguably a greater opportunity for commercial profit and beneficial technological advances (e.g., micromechanical, microfluidic, microthermal, micromagnetic, microoptical and microchemical). However, instead of the traditional evolutionary engineering effort to reduce size and power while simultaneously increasing the performance of such a diverse set of systems, the field of microelectromechanical systems (MEMS) represents an effort to radically transform the scale, performance and cost of these systems by...
Mesoporous silica nanoparticles (MCM-41) coated PEGylated chitosan as a pH-Responsive nanocarrier for triggered release of erythromycin [electronic resource]
, Article International Journal of Polymeric Materials and Polymeric Biomaterials ; 2014, Volume 63, Issue 13, Pages 692-697 ; Mazaheri Tehrani, Zahra ; Sharif University of Technology
Abstract
A pH-responsive drug delivery system based on core shell structure of mesoporous silica nanoparticle (MSN) and chitosan-PEG copolymer was prepared and characterized by Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), scanning electron microscope (SEM), and high-resolution transmission microscope (HR-TEM) techniques. In order to improve compatibility MSN and drug, mesoporous nanosilica was modified by 3-aminopropyl triethoxysilane. The release of erythromycin (a macrolide antibiotic) as a model drug was investigated in two pHs, 7.4 and 5.5
Using Nonlinear Effects of Light for Optical Signal Processing
, M.Sc. Thesis Sharif University of Technology ; Kavehvash, Zahra (Supervisor)
Abstract
Ultrafast signal processing in time-domain with high resolution and reconfigura-bility is a challenging task. This paper, for the first time, introduces a time-varying metasurface consisting of graphene microribbon array for implementing time-lens in the terahertz domain. Given that the surface conductivity of graphene is proportional to the Fermi energy level in the THz regime, it is possible to change the phase property of the incident electromagnetic pulse by changing the Fermi level while the Fermi level itself is a function of voltage. Upon this fact, a quadratic temporal phase modulator, namely time-lens has been realized. This phase modulation is applied to the impinging signal in the...
Theoretical and Computational Investigation of Quantum Plasmonic Properties of Nanocluster Dimers
, M.Sc. Thesis Sharif University of Technology ; Jamshidi, Zahra (Supervisor)
Abstract
In today's era, metal nanoparticles play an important role in technologies emerging from different sciences, such as chemistry, physics, optics, material science, due to their unique characteristics. In the development of nanooptics science, it can be said that metal nanoparticles play an important role. The ability of conductive electrons collective oscillation causes surface charge density fluctuations in nanoparticles, this phenomenon is known as surface plasmons. Surface plasmons are surprisingly coupled with light and cause the significant increase in the intensity of optical fields induced in nanoparticles. Therefore, with the presence of localized surface plasmons or plasmon...
Theoretical Investigation of Ab-initio MD Approach to Increase the Efficiency and Accuracy of VCD Spectrum Calculation
, M.Sc. Thesis Sharif University of Technology ; Jamshidi, Zahra (Supervisor)
Abstract
Understanding of the Molecules is the main purpose of the chemistry. Ab-initio molecular dynamics (AIMD) as a branch of the computational chemistry, tries to give us a deep comprehension of the molecule, and its chemical, physical and optical activities. This comprehension, relies on the accuracy of quantum mechanics, in addition to the speed of the classical mechanics. The mixing of the quantum mechanics and the classical mechanics could simulate activities of the atoms in the time-domain, provided the mixing is done with precaution. This, in turn, helps us to forecast the response of a molecule in different situations, and also translating the macroscopic phenomena in a nanoscopic...
Investigation of Plasmonic Excitation in Carbonic Nanostructures Within Near-IR
, M.Sc. Thesis Sharif University of Technology ; Jamshidi, Zahra (Supervisor)
Abstract
To date, the plasmonic properties of many metallic and semi-conducting materials have been investigated and used in various industries. One of the plasmonic material categories that have always been considered is polycyclic aromatic hydrocarbon or PAH, whose plasmonic resonance energy depends on the charge state of the molecule. In this regard, it is easy to change the plasmonic resonance energy via changing the induced charge, which is a unique feature of the mentioned materials. In addition, plasmonic structures with excitations in the infrared region are able to enhance the vibration intensity of absorbed molecules by increasing the electric field around themselves. Therefore, they have...
Using Simulation-Optimization Approach for Fire Station Location and Vehicle Assignment Problem: a Case Study in Tehran, Iran
, M.Sc. Thesis Sharif University of Technology ; Amini, Zahra (Supervisor)
Abstract
In this research, the problem of locating fire stations and allocating equipment has been studied and a simulation-optimization approach has been presented to solve the problem. The mathematical models of this research were developed based on the idea of the randomness of the covered demand and the maximum expected coverage model. In these models, the issue of non-availability of equipment to cover accidents, the random nature of accidents, various fire incidents and the equipment needed to cover them are considered. Two mathematical models with deterministic and non-deterministic approach with different scenarios for demand are proposed. The non-deterministic model is developed with the aim...
Introducing An Integrated Framework For Solving The Fleet Planning Problem Using A Simulation-Optimization Approach
, M.Sc. Thesis Sharif University of Technology ; Amini, Zahra (Supervisor)
Abstract
One of the main concerns of industrial companies’ managers is providing an efficient logistics system. To achieve an efficient logistics system, the fleet planning problem is studied by many researchers in recent years. This problem consists of multiple sub-problems at three levels: operational, tactical, and strategic. These sub-problems are closely related to each other and need to be studied and addressed in an integrated manner. In this research, an attempt is made to provide an integrated framework to solve the vehicle routing problem (operational), outsourcing problem (tactical), and fleet composition problem (strategic). These problems have various uncertainties, including customer...
A Survey on Searchable Symmetric Encryption Schemes
, M.Sc. Thesis Sharif University of Technology ; Khazaei, Shahram (Supervisor)
Abstract
Using “Searchable Encryption” enables us to encrypt the data, while preserving the possibility of running search queries. One of the most important applications of the mentioned is in Cloud Storage. As users do not trust the Cloud space, they are not inclined to store their data on the Could. The solution to this problem is of course, Cryptography. However, ordinary Cryptography methods, eliminate the data’s searchability. Hence, we need encryption schemes that code the data while retaining their searchability. So far, various schemes has been proposed that differ in their performance, security level, and usage. In this thesis, we aim to discuss and analyze these methods
Temporal Depth Imaging Based on Dispersion
, M.Sc. Thesis Sharif University of Technology ; Kavehvash, Zahra (Supervisor)
Abstract
In this thesis, the aim is designing an optical temporal imaging system. In recent years, due to many applications, including the receipt of high-rate data by slow receivers and compensation of dispersion in telecommunication systems, researchers have considered the topic of temporal imaging. This field of research is based on dispersion, electro-optical modulators or time lenses and space-time theory. By modeling dispersion properties as a depth dimension and taking ideas from three-dimensional spatial imaging systems we intended to increase the temporal resolution and depth of focus of the structure. We also present a novel technique for multiplexing and demultiplexing telecommunication...
Time Domain Optical Signal Processing Based on the Duality Between Dispersion and Diffraction
, M.Sc. Thesis Sharif University of Technology ; Kavehvash, Zahra (Supervisor)
Abstract
In the last decades, due to the growing demand of transferring information with high transmission rates, the complexity and development of telecommunication and optical systems is remarkable. Researchers around the world attempt to explore extraordinary potential of light to process information. In the mid-19th century, scientists discovered a mathematical symmetry between the spatial and temporal optics fields, which originated from the similarity of equations governing the paraxial diffraction of beams and the dispersion of narrow-band pulses known as space– time duality in scientific texts. This new approach provides more advanced and potent methods to temporal processing and...
Improving the Stability of an Urban Traffic Network with Limited Data by Using Percolation Theory and Dynamic Clustering
, M.Sc. Thesis Sharif University of Technology ; Amini, Zahra (Supervisor)
Abstract
One of the most vital aspects of understanding the traffic phenomenon is scrutinizing the traffic transition status, such as the transition from free flow to congestion. The Percolation Theory is a renowned theory focusing on analyzing various network types to detect the critical zones, which are the zones including links that are important to control to improve stability. By calculating the quality indices of network links, the Percolation Theory can simulate the traffic percolation propagation in the network and determine possible critical zones for further analysis. Most studies in this field assume access to data of several traffic parameters for the entire transportation network, such...