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khoshnevis--alireza
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Investigation on Seismic Behavior of Old Masonry Structure (A case study of Daniel historical sanctuary)
, M.Sc. Thesis Sharif University of Technology ; Khalou, Alireza (Supervisor)
Abstract
Masonry structures are complex systems that require a thorough and detailed knowledge for analysis and designing, and especially maintaining their capability. Since the old historical masonry structures have cultural value, maintenance of such structures against natural disasters that cause destruction is important. The goal of this research is to find a method for protection of the historical masonry structure of Daniel shrine that is located in susa region in Khuzestan. According to the reference structures of architectural heritage, a number of challenges in conservation, diagnosis, analysis, monitoring, repair and strengthening are presented that limit the application of modern codes...
On Some Algebraic Structures of the Stanley-Reisner Rings Attached to Simplicial Complexes
, M.Sc. Thesis Sharif University of Technology ; Jafari, Amir (Supervisor)
Abstract
In this thesis, we study the f-vectors and h-vectors of simplicial complexes and we state and prove a theorem of Kruskal and Katona that characterizes the f-vectors of simplicial complexes. We then define the Stanley-Reisner ring A associated to a simplicial complex, and state certain connections between f and h-vectors of this simplicial complex with Hilbert function of A, and show that if A is a Cohen-Macaulay ring then the h-vector of the simplicial complex in an O-sequence. conversely any O-sequence, equivalently, the f-vector of any multicomplex is the h-vector of a simplicial complex. Finally it is shown that if a simplicial complex arises from a triangulation of the sphere and A is...
Analysis of a deterministic power level selection algorithm with small and large power steps for Aloha networks under saturation
, Article Wireless Networks ; Volume 15, Issue 3 , 2009 , Pages 407-418 ; 10220038 (ISSN) ; Khalaj, B. H ; Sharif University of Technology
2009
Abstract
Standard power control techniques are not deployable in Aloha networks due to lack of central controlling entity and/or inefficiency of such algorithms in large networks with bursty traffic. To handle this problem in practice, simple transmission power selection algorithms are used for ranging and/or combating harsh channel conditions. In such algorithms, the transmission power is steadily increased by an amount called power step, until the packet is successfully transmitted. Noting that ranging is the major concern of this approach, small power steps are ideal for its operation. However, as we will show in this paper, using small power steps with this algorithm causes a throughput collapse...
Optimum power selection algorithms in aloha networks: random and deterministic approaches
, Article IEEE Transactions on Wireless Communications ; Volume 6, Issue 8 , 2007 , Pages 3124-3136 ; 15361276 (ISSN) ; Khalaj, B. H ; Sharif University of Technology
2007
Abstract
In this paper, we discuss the optimum random and deterministic power selection algorithms in Aloha networks, where nodes run Exponential Backoff (EB) for contention resolution. In random case, the transmission power of a packet is selected from the available power levels, based on a predetermined probability mass function, while with the deterministic algorithms the transmission power of a packet is a deterministic function of the number of collisions the packet has experienced. Most of the related works in the literature have not addressed the power-throughput characteristics of the power selection algorithms for use in practical system designs and, therefore, this subject has been the...
Optimum QoS classes in interworking of next generation networks
, Article Journal of Communications and Networks ; Volume 9, Issue 4 , 2007 , Pages 438-445 ; 12292370 (ISSN) ; Hossein Khalaj, B ; Sharif University of Technology
Korean Institute of Communication Sciences
2007
Abstract
In this paper, we consider the problem of optimum selection of quality-of-service (QoS) classes in underworking between the networks in a next-generation-network (NGN) environment. After introducing the delay-cost and loss-cost characteristics, we discuss the time-invariant (TI) and time-variant (TV) scenarios. For the TI case, we show that under nearly lossless transmission condition, each network can make its own optimization regardless of other networks. For the TV case, we present sufficient conditions under which the optimum QoS class of each network can be considered fixed with respect to time without considerable degradation in the optimization target. Therefore, under the conditions...
On a decentralized deterministic transmission power level selection algorithm in large aloha networks under saturation
, Article 2006 IEEE International Conference on Communications, ICC 2006, Istanbul, 11 July 2006 through 15 July 2006 ; Volume 12 , 2006 , Pages 5732-5737 ; 05361486 (ISSN); 1424403553 (ISBN); 9781424403554 (ISBN) ; Khalaj, B. H ; Sharif University of Technology
2006
Abstract
In this paper, we will analyze a decentralized transmission power level selection algorithm in conjunction with Binary Exponential Back-off retransmission scheme, in large slotted-Aloha networks under saturation condition. In this algorithm, the transmission power is steadily increased by an amount called power step, until the packet is successfully transmitted. We will use SIR-based capture model to study the performance of this algorithm with small and large power steps. Our analysis proves that, although small power steps may seem favorable for power saving purposes, these power steps face throughput collapse under high load conditions (large number of nodes), while properly chosen large...
Enhancing the Tomo-SAR Images Based on Compressive Sensing Method
, M.Sc. Thesis Sharif University of Technology ; Ghorshi, Mohammad Ali (Supervisor)
Abstract
Radar is a type of active remote sensing instrument that is used to create images of an object, such as a landscape. Synthetic Aperture Radar or SAR is another type of radar which is typically mounted on a moving platform such as an aircraft or a spacecraft and uses the motion of the antenna over the target region to provide finer spatial resolution than is possible with conventional beam-scanning radars. In fact SAR is an advanced form of Side-Looking Airborne Radar (SLAR). The movement of SAR antenna acts as another form of aperture; this aperture combined with the physical aperture of the antenna creates a large "synthetic" antenna aperture (the "size" of the antenna) which enables higher...
Design and analysis of a thermal hydraulic integral test facility for bushehr nuclear power plant
, Article Progress in Nuclear Energy ; Volume 51, Issue 3 , 2009 , Pages 443-450 ; 01491970 (ISSN) ; Jafari, J ; Sohrabpour, M ; Sharif University of Technology
2009
Abstract
In this paper, design and analysis of a thermal hydraulic integral test facility for Bushehr Nuclear Power Plant (NPP) is presented. The Bushehr Integral Test Facility (BITF) is a test facility designed to model the thermal-hydraulic behaviours of the Bushehr NPP (VVER-1000) pressurized water reactors currently in use in IRAN. These reactors have unique features that differ from other PWR designs. The BITF simulates the major components and systems of the reference NPP, making it possible to examine postulated small and medium break a loss of coolant accidents (LOCAs) and operational transients. The BITF is a volume-scaled model (1:1375). To ensure that gravitational forces remain equal to...
Effects of cylinder diameters, reynolds number and distance between two-tandem cylinders on the wake profile and turbulence intensity
, Article ASME-JSME-KSME 2011 Joint Fluids Engineering Conference, AJK 2011 ; Volume 1, Issue PARTS A, B, C, D , 2011 , Pages 3441-3447 ; 9780791844403 (ISBN) ; Jafarian, M. M ; Khoshnevis, A ; Sharif University of Technology
2011
Abstract
A series of experimental and numerical investigations on two tandem cylinders wake have been studied. The velocity profile and turbulence intensity have been acquired by a single one dimensional Hot Wire anemometer. The two cylinders were mounted in a tandem manner in the horizontal mid plane of the working section. The effect of the upstream cylinder diameter, Reynolds number and the distance between the cylinders on the wake profile and turbulence intensity on the downstream cylinder was investigated, while the Reynolds number ranged between1.5× (10)∧4 ∼ 3×(10)∧4. The upstream cylinder diameter (d) was 10, 20 and 25 mm, while the downstream cylinder diameter (D) was 25 mm, corresponding to...
Criteria-based evaluation framework for service-oriented methodologies
, Article UKSim2010 - UKSim 12th International Conference on Computer Modelling and Simulation, 24 March 2010 through 26 March 2010 ; March , 2010 , Pages 122-130 ; 9780769540160 (ISBN) ; Habibi, J ; Shams, F ; Khoshnevis, S ; Sharif University of Technology
2010
Abstract
Service-Oriented Software Engineering is based on concepts and principles for constructing complex enterprise systems in which services as building block of the system, are distributed in large networks. The main goal of the service-oriented methodologies is to define a process for development and maintenance of service-based systems. Most of the Service-Oriented methodologies are not mature enough compared with traditional software development methodologies such as Object-Oriented or Component-Based. Hence, defining an evaluation framework will be useful for comparing methodologies for identifying their strengths and weaknesses, defining new methodologies or extending existing...
On the use of compressive sensing for image enhancement
, Article Proceedings - 2016 UKSim-AMSS 18th International Conference on Computer Modelling and Simulation, UKSim 2016, 6 April 2016 through 8 April 2016 ; 2016 , Pages 167-171 ; 9781509008889 (ISBN) ; Ghorshi, S ; Khoshnevis, S. A ; Pourebrahim, M ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2016
Abstract
Compressed Sensing (CS), as a new rapidly growing research field, promises to effectively recover a sparse signal at the rate of below Nyquist rate. This revolutionary technology strongly relies on the sparsity of the signal and incoherency between sensing basis and representation basis. Exact recovery of a sparse signal will be occurred in a situation that the signal of interest sensed randomly and the measurements are also taken based on sparsity level and log factor of the signal dimension. In this paper, compressed sensing method is proposed to reduce the noise and reconstruct the image signal. Noise reduction and image reconstruction are formulated in the theoretical framework of...
Experimental Study of the Wake behind an MAV using Hot-Wire Anemometer
, M.Sc. Thesis Sharif University of Technology ; Soltani, Mohammad Reza (Supervisor) ; Khoshnevis, Amir (Co-Advisor)
Abstract
In present thesis, experimental study of flow around a two-wing MAV using hot-wire anemometer will be performed which is divided to wake and boundary layer study. This leads to suitable understanding of various parameters affecting its wake and boundary layer. First, effects of upper wing, which has horizontal stabilizer's role, on the main wing's wake will be studied in which effects of angle of attack and distance between the two wings at its cruise velocity will be investigated. Then, effects of angle of attack, velocity and distance between wings on boundary layer of the MAV will be analyzed. Also, experiments are performed at three velocities as 10, 15 and 20 m/s, and three angles of...
Rcci Curvature for Metric-Measure Space via Optimal Transport
, M.Sc. Thesis Sharif University of Technology ; Bahraini, Alireza (Supervisor) ; Ranjbar Motlagh, Alireza (Co-Advisor)
Abstract
One of the important questions in mathematics is generalized. In case of metric spaces, one of the questions is: Can we extend notions of Riemannian geometry to arbitrary metric spaces smoothly? Ricci curvature is one of the most important concepts in differential geometry. Ricci curvature is defined for the Riemannian manifold and has many applications in mathematics and physics like Einstein’s equation in relativity theory. There is a good notion for a metric space having “sectional curvature bounded below by K” or “sectional curvature bounded above by K”, due to Alexandrov. Can we define the concept of Ricci curvature in metric space? A motivation for this question comes from Gromov’s...
, M.Sc. Thesis Sharif University of Technology ; Khaloo, Alireza (Supervisor)
Abstract
Seismic design codes reduce loads by using response modification factor. Because of the reserved strength in structural elements and capacity of structure to dissipate energy, structures can be designed for lower seismic loads. This factor has modified over time. In this thesis, the effect of the reduction in behavior factor on the response of two kinds of reinforced concrete systems were evaluated. Moment resisting frames and dual systems with different heights and regularity in plan, heve been design according to the behavior factor which is recommended in the 3rd edition of the Iranian codes of practice for seismic resistance design of buildings (Standard No. 2800). Drift and...
Prediction of Financial Markets Using Combination of Artificial Intelligence and Technical Analysis
, M.Sc. Thesis Sharif University of Technology ; Haji, Alireza (Supervisor)
Abstract
Generally, nowadays, machine learning methods are used in many different areas for their superiority over other methods of prediction. Although being a tough task, stock market prediction with machine learning approaches is being spread due to satisfying results published ever yday. Machine learning methods usually use varied kinds of data ,including structured data such as market data, technical indicators and some fundamental data as well as unstructured one entailing text and graph data in order to enhance their predictability capacity. In this thesis we aimed to find out more about the importance and the contribution of structured data in prediction and we tried to attain a framework...
, M.Sc. Thesis Sharif University of Technology ; Hajji, Alireza (Supervisor)
Abstract
This thesis presents an inventory control system which is based on Meta-heuristic Algorithms.In this thesis we will optimize the input values of our tree-echelon inventory model (keeping costs,stock worth,reorder costs,...) with these Algorithms. The presented method is able to determine the optimal stock level, costs of system and number of shipments in the system. The method is basically a decision support system (DES) and it is able to provide the order scheduling parameters of goods at operational level. The aim of the current research is to demonstrate that a Meta-heuristic algorithmis capable of solving complex inventory problems and with future improvements it is able to achieve...
Reduction of Residual Displacement of Concrete Structures by use of High Strength Rebars
, M.Sc. Thesis Sharif University of Technology ; Khalu, Alireza (Supervisor)
Abstract
Reinforced concrete bridge columns located in regions of high seismicity are designed with large ductility capacity for adequate protection against collapse. This type of design tends to result in large permanent displacements. To maximize post-event operability and to minimize repair costs, new design strategies to reduce these residual displacements are necessary. Even though seismic codes ensure life safety for bridges, large residual displacement after severe earthquake may make the bridge useless. For example, after 1995 Hyogo-ken Nanbu earthquake (Japan), more than 100 reinforced concrete bridge columns experienced a tilt angle of more than 1 degree (1.75% drift). These columns had to...
Experimental Investigation of the Behavior of Squat Composite Corrugated Shear Walls Under In-Plain Shear
,
M.Sc. Thesis
Sharif University of Technology
;
Khalu, Alireza
(Supervisor)
Abstract
The new lateral load resisting system introduced in this dissertation is a kind of squat composite shear wall consisting of a concrete core as filler and two steel corrugated sheets as cover. Reinforced bars are not used in this kind of construction. Load resisting process of the walls is provided by 3 factors: concrete core, steel corrugated covers on both sides of the central core and shear-friction interaction between the core and covers. There is not any specific formula for their design because of their novelty and few researches on this kind of walls and absence of code provisions. In this project, squat composite walls were constructed with dimensions of 106.8×90 (cm2) from corrugated...
Identification and Abnormal Condition Detection of a Cement Rotary Kiln
, M.Sc. Thesis Sharif University of Technology ; Fatehi, Alireza (Supervisor)
Abstract
One of the most important parts of a cement factory is the cement rotary kiln which plays a key role in quality and quantity of produced cement. In this part, the physical exertion and bilateral movement of air and materials, together with chemical reactions take place. Thus, this system has immensely complex and nonlinear dynamic equations. These equations have not worked out yet. Only in exceptional case; however, a large number of the involved parameters were crossed out and an approximation model was presented instead. This issue caused many problems for designing a cement rotary kiln controller. In this thesis, we employed a nonlinear system identification method for identification,...
Investigating the Behaviour of Concrete Deep Beams With Web Openings Using Finite Element Analysis
, M.Sc. Thesis Sharif University of Technology ; Khaloo, Alireza (Supervisor)
Abstract
Because of absence of adequate studies, design of deep beams with web openings has not yet been covered by most codes of practice. The most studies have been on simply supported deep beams with web openings and have been set up experimentally. There are very few tests of continuous deep beams available in the literature. So it was decided in this thesis the behaviour of concrete continuous deep beams with web openings using finite element software ANSYS to be investigated. Primary purpose of this thesis has been evaluating the use of finite element analysis method for analysis of concrete continuous deep beams with web openings. The next target of this thesis has been assessment of...