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Pre-reduction of Manganese Ore by Natural Gas for Ferromanganese Production
, Ph.D. Dissertation Sharif University of Technology ; Yoozbashizadeh, Hossein (Supervisor) ; Safarian, Jafar (Co-Supervisor)
Abstract
Pre-reduction of some manganese sources (low-grade Venrach and Godar-Sabz ores, high-grade Comilog ore, pellet, pure oxide) by methane gas has been investigated in this research. HSC-Chemistry and FactSage software were used for thermodynamic study of the process. Thermodynamic results indicated that methane may progress to manganese carbide formation, and the reduction process can run autonomously involving less carbon dioxide emission comparing to common ferromanganese process. Several techniques including XRF, XRD, in-situ XRD, SEM-EDS, and thermogravimetry were used in sample characterization and experiments. In addition to the thermal decomposition reactions which were affected by...
Energy and exergy assessments of modified Organic Rankine Cycles (ORCs)
, Article Energy Reports ; Volume 1 , November , 2015 , Pages 1-7 ; 23524847 (ISSN) ; Aramoun, F ; Sharif University of Technology
Elsevier Ltd
2015
Abstract
This paper presents a theoretical framework for the energy and exergy evaluation of a basic as well as three modified Organic Rankine Cycles (ORCs). The modified ORCs considered incorporating turbine bleeding, regeneration and both of them. The results demonstrate that evaporator has major contribution in the exergy destruction which is improved by increase in its pressure. The results confirm that the integrated ORC with turbine bleeding and regeneration has the highest thermal and exergy efficiencies (22.8% and 35.5%) and the lowest exergy loss (42.2 kW) due to decrease in cold utility demand and high power generation
Evaluation of Energy Recovery by Development of Natural Gas Transmission Network Model
, M.Sc. Thesis Sharif University of Technology ; Saboohi, Yadollah (Supervisor)
Abstract
The development of natural gas supply systems and its transmission networks are vitally important to achieve a natural gas economy. Development and planning of natural gas transmission networks as multidisciplinary projects have crucial impact on the economy of gas-rich countries like Iran. The nvestment costs and operation expenses of pipeline networks are so large that even small improvements in system utilization and planning can involve substantial amounts of money. A large number of technological options exist for development in conversion, distribution levels and …, which cause various pathways for supplying natural gas. In addition there are many energy recovery technologies along...
Modeling and technical-economic optimization of electricity supply network by three photovoltaic systems
, Article Journal of Solar Energy Engineering, Transactions of the ASME ; Vol. 136, issue. 2 , 2014 ; ISSN: 0199-6231 ; Khodaparast, P ; Kateb, M ; Sharif University of Technology
2014
Abstract
To attain an ongoing electricity economy, developing novel widespread electricity supply systems based on diverse energy resources are critically important. Several photovoltaic (PV) technologies exist, which cause various pathways to produce electricity from solar energy. This paper evaluates the competition between three influential solar technologies based on photovoltaic technique to find the optimal pathways for satisfying the electricity demand: (1) multicrystalline silicon; (2) copper, indium, gallium, and selenium (CIGS); and (3) multijunction. Besides the technical factors, there are other effective parameters such as cost, operability, feasibility, and capacity that should be...
Evaluation of energy recovery and potential of hydrogen production in Iranian natural gas transmission network
, Article Energy Policy ; Volume 61 , 2013 , Pages 65-77 ; 03014215 (ISSN) ; Saboohi, Y ; Kateb, M ; Sharif University of Technology
2013
Abstract
In the natural gas transmission network, from supply points to demand nods there are various technological options that include processing, transportation, conversion and gas distribution. Comprehensive analysis of natural gas network requires evaluation of different chains of gas flow through various levels based on economical and environmental criteria subject to technical and operational constraints such as feasibility, operability and reliability of different alternatives. To aid decision-making process in the sector of natural gas, a generic optimization-based model has been developed for assessing long term energy issues related to planning and design of natural gas supply systems. The...
Designing a Low Power Receiver for Medical Implant Communications Service
, M.Sc. Thesis Sharif University of Technology ; Safarian, Amin Ghasem (Supervisor)
Abstract
One of the most important parameters of implanted chip in body is its ability to work for a long time without the need for battery change. Hence designing radio frequency transceivers used in these chips should be done with the lowest possible power consumption. Of course it should be noticed that for correct communication, standard specifications must be meeted. In this thesis, a receiver in medical implant communication service standard with the goal of minimal power consumption is designed. In circuit design different challenges such as low inductor quality factor, threshold voltage of transistors and usual trade-offs between receiver parameters are faced. Therefore, previous used...
Novel frequency synthesizer for spur level reduction
, Article 27th Iranian Conference on Electrical Engineering, ICEE 2019, 30 April 2019 through 2 May 2019 ; 2019 , Pages 76-81 ; 9781728115085 (ISBN) ; Ghajari, S ; Safarian, A ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2019
Abstract
A novel frequency synthesizer architecture for reducing spur level is presented. By using a feedforward path a new zero in the transfer function is generated which enables us to increase the capacitor tied to the control voltage line and thus reducing spur level. A fast settling technique is also used to compensate the effect of spur reduction technique on settling time. Different blocks of frequency synthesizer are implemented in MATLAB/Simulink. Simulations show 13 dB improvement in reference spur level compared to conventional architecture for a 2.4 GHz frequency synthesizer
Gaseous reduction of manganese ores: A review and theoretical insight
, Article Mineral Processing and Extractive Metallurgy Review ; Volume 41, Issue 3 , 2020 , Pages 198-215 ; Yoozbashizadeh, H ; Safarian, J ; Sharif University of Technology
Taylor and Francis Inc
2020
Abstract
Gaseous reduction of manganese ores has been studied as it is beneficial for both understanding the common ferromanganese production process and the development of new processes. Thermodynamics, kinetics, and the mechanisms of reduction by methane have been reviewed, supported by thermodynamic calculations from the commercial HSC Chemistry and FactSage software. While there were similarities in reduction process by CO and H2, methane was a more efficient reductant and yielded reduction levels beyond MnO, which was due to the large thermodynamic driving force for carbide formation by metastable methane. The practical aspects of gaseous reduction by methane, such as application of a...
5-6 GHz dual-vector phase shifter in 0.18 μm LID CMOS
, Article 27th Iranian Conference on Electrical Engineering, ICEE 2019, 30 April 2019 through 2 May 2019 ; 2019 , Pages 82-86 ; 9781728115085 (ISBN) ; Fakharzadeh, M ; Safarian, A ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2019
Abstract
In this paper, a low power active phase shifter in 0.18 μm CMOS technology, operating from 5 to 6 GHz, for WLAN applications is presented. Design equations for this novel structure, which consists of two current steering stages, transconductance stage and DACs, are derived, thoroughly. This phase shifter has a range of 360° with 5.625° phase resolution. The power consumption is 35 mW. The RMS phase error is only 0.3°. The simulated power gain, input P1dB, and NF are 4 dB, -0.8 dBm and 6 dB, respectively
FoM Optimization in Class-C Oscillators
, M.Sc. Thesis Sharif University of Technology ; Safarian, Amin Ghasem (Supervisor)
Abstract
A key point in designing class-C oscillators is maximizing the Figure-of-Merit (FoM). For this purpose, changing the oscillator’s structure or adjusting its bias current may be used. Previous literatures mostly limit their efforts to the first case, leaving the issue of determining the proper bias current almost untouched. In this work, a new approach recruiting DC voltage of the common source node of the switching pair transistors as an indicator has been presented. Using theoretical analysis, it has been shown that maximizing this voltage will optimize the oscillator in term of the FoM. The proposed indicator has the advantages of not introducing any loading effect to the output node, and...
Design and Implementation a Smart System for Controlling and Protection of Tele-Communication Manholes
, M.Sc. Thesis Sharif University of Technology ; Safarian, Amin Ghasem (Supervisor)
Abstract
The telecommunication manhole is a place that the cables of the telephone network are located on it. line Inside these manholes, there are equipment and cables for telephone. The number of these places is many, so protection and maintenance of the manholes have been problematic in case of theft of the cap, equipment inside them and flooding. Also, lack of inspection officers and the high cost of repairing and replacing parts inside them, has made it difficult for telecom companies to handle these problems. The only way to connect the manhole is a telephone line inside them. Also, there is no proper electrical power inside the manhole, so the design and implementation of a system that...
Designing a Low Power Transmitter for Medical Implant Communications Service
, M.Sc. Thesis Sharif University of Technology ; Safarian, Aminghasem (Supervisor)
Abstract
One of the most important parameters of an implanted device in the human body is its ability to operate for a long time to decrease the need for surgery in order to replace the battery. Therefore, the radio transceivers in these devices are designed in such a way to reduce the power consumption as much as possible. But, at the same time, it is crucial that the bit error rate be as small as possible to decrease the number of incorrect sent and received bits. Thus, the phase noise should also be as small as possible in order to reduce the bit error rate. In this thesis, a transmitter has been designed for Medical Implant Communications Service standard. In order to reduce the power...
A new single-loop single-stage low power sigma-delta modulator
, Article 14th International Conference on Microelectronics, ICM 2002, 11 December 2002 through 13 December 2002 ; Volume 2002-January , 2002 , Pages 215-218 ; 0780375734 (ISBN) ; Sahandi, F ; Mojtaba Atarodi, S ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2002
Abstract
This paper presents a new single-loop single-stage second order sigma-delta modulator. The circuit based on switched capacitor components just uses one Op-Amp to realize second order noise shaping. The modulator demonstrated 85 dB DR in 8kHz bandwidth, dissipating 135 μW from a 2.5 V supply. © 2002 IEEE
A new low-power sigma-delta modulator with the reduced number of op-amps for speech band applications
, Article Proceedings of the 2003 IEEE International Symposium on Circuits and Systems, Bangkok, 25 May 2003 through 28 May 2003 ; Volume 1 , 2003 , Pages I1033-I1036 ; 02714310 (ISSN) ; Sahandi, F ; Mojtaba Atarodi, S ; Sharif University of Technology
2003
Abstract
An area and power-efficient second order sigma-delta modulator is presented. At system level, we propose a new single-loop single-stage modulator that uses only one class-AB op-amp to realize a second order noise shaping for speech band applications. The modulator shows 86 dB DR in 4 kHz speech bandwidth. It consumes 125 μw from a 2.5 V supply
Design of Ultra Low Power RF Front-End Based on Current Reuse for Bluetooth Low Energy Standard
, M.Sc. Thesis Sharif University of Technology ; Safarian, Aminghasem (Supervisor) ; Atarodi, Mojtaba (Co-Supervisor)
Abstract
Bluetooth low energy, originally developed by Nokia as wibree, was formally introduced by SIG group in 2010. It is a promising technology for internet of things (IoT) which needs ultra low power consumption. Unlike digital circuits that the power consumption decreases with technology scaling and consequently decreasing the supply voltage, the scaling has not such effect in analog circuits for two reasons. First, the power consumption of an analog circuit is mainly determined by its noise and linearity specification which in almost all cases is determined by the standard. Second, due to noise consideration, analog designers prefer to not to use the latest technology for example because of...
A low-power, second-order Δ/∑ modulator using a single class-AB op-amp for voice-band applications
, Article Analog Integrated Circuits and Signal Processing ; Volume 49, Issue 2 , 2006 , Pages 199-211 ; 09251030 (ISSN) ; Sahandiesfanjani, F ; Heydari, P ; Atarodi, S. M ; Sharif University of Technology
2006
Abstract
The design of a power-efficient second-order Δ/∑ modulator for voice-band is presented. At system level, a new single-loop, single-stage modulator is proposed. The modulator employs only one class-AB op-amp to realize a second-order noise shaping for voice-band applications. The modulator is designed in a 0.25μm standard CMOS process, and exhibits 86 dB dynamic range (DR) for a 4 kHz voice-bandwidth. The proposed modulator consumes 125μW from a 2.5 V supply. © Springer Science + Business Media, LLC 2006
Towards a Method for Inferring Trust
, M.Sc. Thesis Sharif University of Technology ; Habibi, Jafar (Supervisor)
Abstract
People usually use trust and reputation when they encounter uncertainty in the nature. Graphs are good tools to model and analysis of trust’s problems. If we show human and computer agents by graph’s nodes and trust values by its edges, in literature, the output graph is so-called Web of Trust. Most recently, there are three major research areas in which trust is studied. First area is policy-based trust which uses policies, digital signature and authentication methods. Second area is reputation-based trust which uses reputation and social network tools to estimate trust where past interactions or performance for an entity are combined to assess its future behavior. Third area is trust...
Efficient Search in Peer-to-Peer Networks
, Ph.D. Dissertation Sharif University of Technology ; Habibi, Jafar (Supervisor)
Abstract
Peer-to-Peer networks are invented to enable participants (peers) to share their resources and find and use the shared resources of the others. So the main issue is the mechanism of finding granted resources of the other peers. In Peer-to-Peer networks, there is no central server to index shared resources of the peers. So peers should collaborate to provide a fully distributed mechanism for searching resources. Considering the huge size of peer-to-peer systems, it is apparent that efficiency of the search mechanism is very critical. In this thesis, to have efficient seach in Peer-to-Peer networks, we propose two approaches. Then based on these approaches, we propose the third approach to...
Deployment of Component-Based Applications in Distributed Environments
, M.Sc. Thesis Sharif University of Technology ; Habibi, Jafar (Supervisor)
Abstract
With significant advances in software development technologies in recent years, it is possible to have complex software applications, wich include large number of heterogeneous software components distributed over a large network of computers with different computational capabilities. To run such applications, their components must be instantiated on proper hardware resources in their target environments so that all requirements and constraints are met and some quality of service parametesrs (e.g.,reliability, load balancing, etc) are also optimized. This process is called software deployment. For large, distributed ,component-based applications¬ with many constraints and requirements, it ...
Improving Exploiting of Network Resources in Peer to Peer Overlay Networks
, M.Sc. Thesis Sharif University of Technology ; Habibi, Jafar (Supervisor)
Abstract
Today, peer to peer networks have become quite popular due to their ability to easy access to shared resources regardless of their location in World. In these systems files are stored at the end user machines which named peer, rather than at a central server, in contrast to the traditional client-server systems, files are transferred directly between peers. sending and receiving those data, occupy a large amount of the internet bandwidth. So, by improving the efficiency of these networks, the total efficiency of the internet will improved. These systems are usually constructed on the other networks such as TCP/IP as an underlay or physical networks. Despite of structure of peer to peer...