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Investigation of in situ prepared polypropylene/clay nanocomposites properties and comparing to melt blending method
, Article Materials and Design ; Volume 31, Issue 1 , 2010 , Pages 76-84 ; 02641275 (ISSN) ; Ramazani S. A. A ; Javan Nikkhah, S ; Sharif University of Technology
2010
Abstract
The morphological, physical and mechanical properties of polypropylene/clay nanocomposites (PPCNs) were prepared by in situ polymerization are investigated. Non-modified scmectite type clay (e.g. bentonite) was used to prepare bi-supported Ziegler-Natta catalyst of TiCl4/Mg(OEt)2/clay. Exfoliated PPCNs were obtained by in situ intercalative polymerization of propylene using produced bi-supported catalyst. X-ray diffraction (XRD) patterns and transmission electron microscopy (TEM) micrograph were used to assess the clay morphology and dispersion of clay. The crystalline structures of PPCNs were characterized by differential scanning calorimetry (DSC). The mechanical properties of PPCNs were...
Investigation of properties of polyethylene/clay nanocomposites prepared by new in situ ziegler-natta catalyst
, Article Materials and Design ; Volume 30, Issue 7 , 2009 , Pages 2309-2315 ; 02641275 (ISSN) ; Ramazani Saadat Abadi, A ; Baniasadi, H ; Tavakolzadeh, F ; Sharif University of Technology
2009
Abstract
This paper is devoted to investigation of morphological and physical-mechanical properties of polyethylene (PE)/clay nanocomposites prepared via in situ polymerization method using bi-supported Ziegler-Natta catalyst. Bentonite type clay and MgCl2 (ethoxide type) were used as the support of TiCl4. Catalyst support and polymerization process have been done in slurry phase using Triisobutylaluminum as the co-catalyst. The microstructure of the nanocomposites was examined by X-ray diffraction (XRD) and transmission electron microscopy (TEM). XRD and TEM indicated that almost fully exfoliated PE/clay nanocomposites were produced successfully using this method. According to permeability...
Resource Management in Space-Division Multiplexed Elastic Optical Networks
, M.Sc. Thesis Sharif University of Technology ; Pakravan, Mohammad Reza (Supervisor)
Abstract
In recent years, Internet traffic has nearly doubled in the core network every two years, and it is expected to continue to grow in the future. With this growth, there is a need for very high capacity and economically efficient transmission systems, which optical communication is the best choice. Elastic optical network (EON) is one of the best options for achieving this goal in the future. Unlike existing networks, the transmission parameters of EON will be customizable, which will have an essential role in optimizing bandwidth assignment. The problem facing scientists today is to approach the final physical capacity of current optical fibers. The solution proposed for this challenge is...
Development of Computational Fluid Dynamics Model for Spatial Distribution of Greenhouse Temperature and Humidity Considering Plant Evapotranspiration
, M.Sc. Thesis Sharif University of Technology ; Roshandel, Ramin (Supervisor)
Abstract
The purpose of this study is to develop a simulated model of a greenhouse using two different ventilation systems, a fan&pad system and an air-soil converter equipped with a sprinkler in order to compare the cooling performance of these two systems in hot seasons. The main focus of the analysis of the results is on how the temperature and humidity are distributed throughout the greenhouse space. In order to develop a three-dimensional model with computational fluid dynamics method, greenhouse simulation in Ansis software has been used. The development of ventilation model in the greenhouse is done by creating boundary conditions using optimal design. Also, to simulate soil-air conditioning...
Effects of obstacles on inertial focusing and separation in sinusoidal channels: An experimental and numerical study
, Article Chemical Engineering Science ; Volume 276 , 2023 ; 00092509 (ISSN) ; Amiri, H. A ; Moshafi, S ; Karimi, A ; Nikkhah, A ; Chen, X ; Ta, H. T ; Nguyen, N. T ; Zhang, J ; Sharif University of Technology
Elsevier Ltd
2023
Abstract
Inertial microfluidics manipulates and separates microparticles based on the finite inertia of the fluid at high flow speed. In inertial microfluidics, modifying the geometry by embedding periodic micro-obstacles into curvilinear channels is emerging as a promising strategy to improve inertial focusing and separation. This work systematically investigated the influence of micro-obstacles on inertial focusing and developed a high-resolution microfluidic device for particle and cell separation. First, we developed numerical modelling to simulate the migration trajectories of particles. Then, we studied the effects of various obstacles on the inertial focusing in the sinusoidal channels. The...
A comprehensive review on atmospheric water harvesting technologies: From thermodynamic concepts to mechanism and process development
, Article Journal of Water Process Engineering ; Volume 53 , 2023 ; 22147144 (ISSN) ; Azmi, W. M. B. W ; Nikkhah, A ; Najafi, A. M ; Babaei, M. M ; Fen, C. S ; Nouri, A ; Mohammad, A. W ; Lun, A. W ; Yong, N. L ; Mahmoudi, E ; Sharif University of Technology
Elsevier Ltd
2023
Abstract
Water scarcity is one of the most challenging problems that the world has ever faced. There are numerous methods to remedy the water crises. One is using atmospheric water harvesting (AWH) to provide water. So far, there is much research on the subject of AWH. However, there is still a lack of establishing an extensive comparison between different technologies and methods used to harvest atmospheric water. In this review, we provide details on the thermodynamic performance of the AWH system. The systems are categorized into both active and passive systems. Heat pumps, membranes, thermoelectric solar systems, and adsorption systems are some atmospheric harvesting technologies that will be...
Investigation of Production Increasing in In-situ Preparation of Polyolefin/clay Nanocomposites
, M.Sc. Thesis Sharif University of Technology ; Ramazani Saadat Abadi, Ahmad (Supervisor)
Abstract
This project is devoted to experimental investigation of increasing on production of polyethylene/clay nanocomposites (PECNs) and polypropylene/clay nanocomposites (PPCNs) via in-situ polymerization method. First of all we produced bi-supported Ziegler-Natta catalyst to polymerized polyolefins nanocomposites. Bentonite type clay and Magnesiumethoxide (Mg (OEt)2) were used as the support of Tetrachloridetitanium (TiCl4). Catalyst support and polymerization process have been done in slurry phase using Triisobutylaluminum (TiBA) as the co-catalyst. The efficiency of preapared bi-supported Ziegler-Natta was reasonably high (average 200 (gr. Product/mmol Ti. h) for PECNs and 195 (gr. Product/mmol...
The Design and Construction of a Marine Current Turbine and Modeling the Flow Around It
, M.Sc. Thesis Sharif University of Technology ; Seif, Mohammad Saeed (Supervisor) ; Abbaspour, Madjid (Supervisor)
Abstract
Nowadays, science and technology, once again, lead approach to renewable natural resources to access energy due to fossil resources restrictions. Growing need for energy, being concerned about exhaustion of fossil resources, environmental pollution caused by burning fossil materials, climate warming and the greenhouse effect and etc. are obvious evidences of aforesaid fact. On the other hand, oceans and seas are large reservoirs of energy which comes from sunlight, geothermal resources, Earth's rotation and gravity by means of mechanical and hydrothermal processes. During the years, many ideas were conducted to achieve and mine the mentioned enormous energy potential of the oceans and seas....
A selective chemiresistive sensor for the cancer-related volatile organic compound hexanal by using molecularly imprinted polymers and multiwalled carbon nanotubes
, Article Microchimica Acta ; Volume 186, Issue 3 , 2019 ; 00263672 (ISSN) ; Banan Nojavani, M ; Nikkhah, M ; Alizadeh, T ; Esfandiar, A ; Ganjali, M. R ; Sharif University of Technology
Springer-Verlag Wien
2019
Abstract
A chemiresistive sensor is described for the lung cancer biomarker hexanal. A composite consisting of molecularly imprinted polymer nanoparticles and multiwalled carbon nanotubes was used in the sensor that is typically operated at a voltage of 4 V and is capable of selectively sensing gaseous hexanal at room temperature. It works in the 10 to 200 ppm concentration range and has a 10 ppm detection limit (at S/N = 3). The sensor signal recovers to a value close to its starting value without the need for heating even after exposure to relatively high levels of hexanal
Multi-objective market clearing model with an autonomous demand response scheme
, Article Energies ; Volume 12, Issue 7 , 2019 ; 19961073 (ISSN) ; Shafie Khah, M ; Badakhshan, S ; Aghaei, J ; Mariano, S. J. P. S ; Catalão, J. P. S ; Sharif University of Technology
MDPI AG
2019
Abstract
Demand response (DR) is known as a key solution in modern power systems and electricity markets for mitigating wind power uncertainties. However, effective incorporation of DR into power system operation scheduling needs knowledge of the price–elastic demand curve that relies on several factors such as estimation of a customer’s elasticity as well as their participation level in DR programs. To overcome this challenge, this paper proposes a novel autonomous DR scheme without prediction of the price–elastic demand curve so that the DR providers apply their selected load profiles ranked in the high priority to the independent system operator (ISO). The energy and reserve markets clearing...
Network delay analysis of a (σ, ρ) - Regular traffic stream over multiple paths in a network of fair-queuing servers
, Article 2013 Iran Workshop on Communication and Information Theory ; May , 2013 , Page(s): 1 - 6 ; 9781467350235 (ISBN) ; Golestani, S. J ; Sharif University of Technology
2013
Abstract
In this paper, we analyze the worst-case delay performance of a network of fair queuing servers in case of multiple-paths between source-destination pairs. In order to develop worst-case delay analysis for the multiple-path scenario, two challenging events should be addressed: merging different sub-streams of a session as well as distributing a traffic stream among different paths (traffic partitioning). Specifically, we propose to merge incoming sub-streams of a session to a node according to a limited rate Fair Queuing (FQ) scheme. Although the merged stream is treated as a unity, this approach results in a guaranteed level of service to each sub-stream. In addition, an algorithm is...
Synthesis and reactivity of unsymmetrical Schiff base ligand towards Ni(II), Cu(II) and Pd(II)
, Article Synthesis and Reactivity in Inorganic and Metal-Organic Chemistry ; Volume 30, Issue 8 , 2000 , Pages 1535-1545 ; 00945714 (ISSN) ; Sabounchei, S. J. S ; Rayati, S ; Sharif University of Technology
Marcel Dekker Inc
2000
Abstract
The unsymmetrical Schiff base 1′-hydroxy-2′-acetonaphthoneacetylacetone-ethylendiimine (Hhan)(Hacac)en and its complexes with some transition metals have been synthesized and characterized by elemental analyses, conductometric measurements, infrared and electronic absorption, NMR and mass spectroscopy
Comprehensive study on a 2 × 2 full-rate and linear decoding complexity space-time block code
, Article IET Communications ; Volume 9, Issue 1 , 2015 , Pages 122-132 ; 17518628 (ISSN) ; Talebi, S ; Abouei, J ; Sharif University of Technology
Institution of Engineering and Technology
2015
Abstract
This paper presents a comprehensive study on the Full-Rate and Linear-Receiver (FRLR) STBC proposed as a newly coding scheme with the low decoding complexity for a 2×2 MIMO system. It is shown that the FRLR code suffers from the lack of the non-vanishing determinant (NVD) property that is a key parameter in designing a full-rate STBC with a good performance in higher data rates, across QAM constellation. To overcome this drawback, we show that the existence of the NVD feature for the FRLR code depends on the type of the modulation. In particular, it is analytically proved that the FRLR code fulfills the NVD property across the PAM constellation but not for the QAM scheme. Simulation results...
Maximum fractional forcing number of the powers of even cycles
, Article Advanced Studies: Euro-Tbilisi Mathematical Journal ; Volume 16, Issue 1 , 2023 , Pages 1-11 ; 26679930 (ISSN) ; Karimy, S ; Ranjbarzadeh, S ; Sharif University of Technology
Tbilisi Centre for Mathematical Sciences
2023
Abstract
In this work, we find upper and lower bounds on the maximum fractional forcing number of the Cartesian power of even cycles. Our result can extend the result of [3] about the maximum forcing number of C2n□C2n to that of the product of an arbitrary number of even cycles of the same lengths. © 2023 Global-Science Press
Ranking locations for producing hydrogen using geothermal energy in Afghanistan
, Article International Journal of Hydrogen Energy ; Volume 45, Issue 32 , 2020 , Pages 15924-15940 ; Hosseini Dehshiri, S. J ; Hosseini Dehshiri, S. S ; Sharif University of Technology
Elsevier Ltd
2020
Abstract
Geothermal energy is a type of renewable energy with high availability and independence from climatic and atmospheric conditions. It has been shown that geothermal energy is technically, economically and environmentally more suitable for hydrogen production than other renewable sources. Hydrogen has wide applications in many fields including cooling, oil, gas, petrochemical, nuclear, and energy industries. Afghanistan has significant potential in geothermal power generation and also several hydrogen-consuming industries that provide opportunities for geothermal-based hydrogen production. This study attempted to find suitable locations for the construction of geothermal power plant for...
Removal of airborne hexavalent chromium mist using chitosan gel beads as a new control approach
, Article International Journal of Environmental Science and Technology ; Volume 3, Issue 3 , 2006 , Pages 305-313 ; 17351472 (ISSN) ; Golbabaei, F ; Hamedi, J ; Nourijelyani, K ; Shahtaheri, S. J ; Moosavi, S. R ; Sharif University of Technology
CEERS
2006
Abstract
Airborne hexavalent chromium is a known human respiratory carcinogen and allergen. Many workers are exposed to hexavalent chromium in various processes which chromium electroplating plants are the most common. In this study, the feasibility of a new control approach to remove this pollutant using chitosan beads as a biosorbent was investigated. Hexavalent chromium sorption was studied relative to pH, pollution concentration, sorbent concentration, temperature, and air velocity using one factor at a time approach and Taguchi experimental design. Polluted air with different chromium mist concentrations (10-5000 μg/m3) was contacted to chitosan beads (3.3-20 g/L), floating in distilled water...
Nanostructured particles for controlled polymer release in enhanced oil recovery
, Article Energy Technology ; Volume 4, Issue 9 , 2016 , Pages 1035-1046 ; 21944288 (ISSN) ; Ramazani S., A ; Shaban, M ; Ayatollahi, S ; de la Cal, J. C ; Sheng, J. J ; Tomovska, R ; Sharif University of Technology
Wiley-VCH Verlag
2016
Abstract
With the decline in oil discoveries over recent decades, it is believed that enhanced oil recovery (EOR) technologies will play a key role to meet energy demand in the coming years. Polymer flooding is used commonly worldwide as an EOR process. In this work, we propose the synthesis of protected polyacrylamide (PAM) nanoparticles (PPNs) with a hydrophobic polystyrene (PSt) shell by one-pot two-step inverse emulsion polymerization, in which the PSt shell was created by surface polymerization. The shell protects the active PAM chains from premature degradation caused by the harsh environment in the reservoirs, controls the release of the chains as rheological modifiers, and additionally, it...
Cover picture: Nanostructured particles for controlled polymer release in enhanced oil recovery (energy technol. 9/2016)
, Article Energy Technology ; Volume 4, Issue 9 , 2016 , Pages 1029- ; 21944288 (ISSN) ; Ramazani S., A ; Shaban, M ; Ayatollahi, S ; de la Cal, J. C ; Sheng, J. J ; Tomovska, R ; Sharif University of Technology
Wiley-VCH Verlag
2016
Abstract
Abstract original image Smart Enhanced Oil Recovery Process using Core–Shell Nanoparticles: The cover image denotes schematically the enhanced oil recovery process by flooding using an aqueous dispersion of core–shell nanoparticles made up of protected polyacrylamide nanostructures (PPNs). Y. Tamsilian and his colleagues at Sharif University of Technology (Iran) and the Institute for Polymer Material (POLYMAT, Spain) demonstrated the synthesis of polyacrylamide nanoparticles protected with a hydrophobic polystyrene shell by using a one-pot, two-step inverse emulsion polymerization technique, where the polystyrene shell was created by surface polymerization. The presence of the hydrophobic...
A framework for decision support systems based on Zachman framework
, Article Advanced Techniques in Computing Sciences and Software Engineering, 5 December 2008 through 13 December 2008 ; 2010 , Pages 497-502 ; 9789048136599 (ISBN) ; Habibi, J ; Ostadzadeh, S. A ; Sharif University of Technology
2010
Abstract
Recent challenges have brought about an inevitable tendency for enterprises to lunge towards organizing their information activities in a comprehensive way. In this respect, Enterprise Architecture (EA) has proven to be the leading option for development and maintenance of information systems. EA clearly provides a thorough outline of the whole information system comprising an enterprise. To establish such an outline, a logical framework needs to be laid upon the entire information system. Zachman framework (ZF) has been widely accepted as a standard scheme for identifying and organizing descriptive representations that have critical roles in enterprise management and system development. In...
Impact of void ratio and state parameters on the small strain shear modulus of unsaturated soils
, Article 15th Asian Regional Conference on Soil Mechanics and Geotechnical Engineering, ARC 2015: New Innovations and Sustainability ; 2015 , Pages 241-246 ; Gheibi, A ; Rahimi, M ; McCartney, J. S ; Haeri, S. M
2015
Abstract
The unsaturated small strain shear modulus, Gmax, is a key reference value in predicting relationships between dynamic shear modulus and shear strain amplitude and is thus a key quantity to properly model the behavior of dynamically-loaded geotechnical systems such as pavements, rail beds, and machine foundations. From the interpretation of the experimental Gmax results for unsaturated soils, different definitions of trends between Gmax and the stress state of the unsaturated soils and material properties are proposed. However, in most of trends, the relationship between the stress state and void ratio is considered and the effect of void ratio on the unsaturated small strain shear modulus...