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mokhtar--ali-reza
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Developing an Applied Model for Energy Management in Dairy Production Industry
, M.Sc. Thesis Sharif University of Technology ; Mokhtar, Ali Reza (Supervisor) ; Miremadi, Ali Reza (Supervisor)
Abstract
Reviewing trends of energy consumption in the world reveals that sooner or later energy resources will be depleted. This concerning rate of consumption has brought about more greenhouse gases (GHG) emission influencing deleteriously on environment and climate. Human has continued energy consumption to maintain and improve the quality of his life through industrial production. Industry as a significant energy user owns considerable contribution to this consumption. Several attempts have been carried out to develop energy management systems in order to improve the energy efficiency of industrial sectors. Whilst they are comprehensive and could be applied to any sector, there is lack of...
Model reduction techniques for unstable second order-form systems
, Article IEEJ Transactions on Electrical and Electronic Engineering ; Volume 16, Issue 3 , 2021 , Pages 445-454 ; 19314973 (ISSN) ; Mohd Mokhtar, R ; Haider, S ; Bukhari, S. H. R ; Rasool, A ; Sharif University of Technology
John Wiley and Sons Inc
2021
Abstract
In the present work, multiple non existing model order reduction (MOR) techniques for unstable second-order form systems (SOSs) are proposed. For unstable SOSs, continuous-time algebraic Lyapunov equations get unsolvable that halt the reduction process. To avoid this problem, unstable SOS is first decomposed into stable and unstable portions and balanced truncation is applied to the stable part. The obtained reduced order model (ROM) for the stable portion is augmented with the unstable portion to obtain the overall reduced system. It is observed that the second-order structure in ROM for the first technique gets lost as well as augmented unstable dynamics degrade the ROM performance. To...
Model reduction techniques for unstable second order-form systems
, Article IEEJ Transactions on Electrical and Electronic Engineering ; Volume 16, Issue 3 , 2021 , Pages 445-454 ; 19314973 (ISSN) ; Mohd-Mokhtar, R ; Haider, S ; Bukhari, S. H. R ; Rasool, A ; Sharif University of Technology
John Wiley and Sons Inc
2021
Abstract
In the present work, multiple non existing model order reduction (MOR) techniques for unstable second-order form systems (SOSs) are proposed. For unstable SOSs, continuous-time algebraic Lyapunov equations get unsolvable that halt the reduction process. To avoid this problem, unstable SOS is first decomposed into stable and unstable portions and balanced truncation is applied to the stable part. The obtained reduced order model (ROM) for the stable portion is augmented with the unstable portion to obtain the overall reduced system. It is observed that the second-order structure in ROM for the first technique gets lost as well as augmented unstable dynamics degrade the ROM performance. To...
Feedback control of the neuro-musculoskeletal system in a forward dynamics simulation of stair locomotion [electronic resource]
, Article Proc. of IMechE Part H: Journal of Engineering in Medicine ; 2009, Vol. 223, No. 6, pp. 663-675 Journal of NeuroEngineering and Rehabilitation ; Volume 11, Issue 1, 30 April 2014, Article number 78 ; Meghdari, Ali ; Vossough, Gholam Reza ; Sharif University of Technology
Abstract
The aim of this study is to employ feedback control loops to provide a stable forward dynamics simulation of human movement under repeated position constraint conditions in the environment, particularly during stair climbing. A ten-degrees-of-freedom skeletal model containing 18 Hill-type musculotendon actuators per leg was employed to simulate the model in the sagittal plane. The postural tracking and obstacle avoidance were provided by the proportional—integral—derivative controller according to the modulation of the time rate change of the joint kinematics. The stability of the model was maintained by controlling the velocity of the body's centre of mass according to the desired centre of...
Machining precedence of 21/2D interacting features in a feature-based data model
, Article Journal of Intelligent Manufacturing ; Volume 22, Issue 2 , 2011 , Pages 145-161 ; 09565515 (ISSN) ; Xu, X ; Sharif University of Technology
2011
Abstract
In process planning, determining feature's machining precedence is an essential step. The task becomes more difficult if features interact with each other, in which case the feature precedence information may suggest multiple machining sequences of the features. This paper considers interacting features in a feature-based model for process planning tasks. For each feature, precedence information is generated considering both roughing and finishing operations. A rule-based system is developed and implemented based on the information about machining precedence of the interacting features. The STEP-NC data model is used as the underlying data model. This model is object-oriented and compliant...
Introducing a roadmap to implement the universal manufacturing platform using axiomatic design theory
, Article International Journal of Manufacturing Research ; Volume 5, Issue 2 , 2010 , Pages 252-269 ; 17500591 (ISSN) ; Houshmand, M ; Sharif University of Technology
2010
Abstract
In competitive environment of quick market changes, developing an interoperable manufacturing system is a necessity. To realise interoperability, the exchange of part and product data must be independent of their platforms. There are two basic approaches for this purpose: i utilising interfaces ii utilising neutral formats. Standard for the Exchange of Product data (STEP) plays a significant role as a neutral data model to integrate design, manufacturing and other activities in product life cycle. To implement a Universal Manufacturing Platform (UMP), a systematic roadmap is required. The current paper proposes such a roadmap using the methodology of Axiomatic Design (AD)
Integration of Design and Manufacturing Systems Using Neutral Data Structure
, Ph.D. Dissertation Sharif University of Technology ; Hooshmand, Mahmoud (Supervisor)
Abstract
In competitive environment of quick market changes, developing an interoperable manufacturing system is a necessity. Process planning as a connection link between design and manufacturing, has never been able to integrate these up/down stream activities and in spite of employing computer systems, CAPP’s information has been managed in an isolated manner. To realize interoperability, the exchange of part and product data must be independent of their platforms. There are two basic approaches for this purpose: i) Utilizing interface and ii) Utilizing neutral formats. STEP (Standard for the Exchange of Product data) plays a significant role as a neutral data model to integrate design,...
Properties of the Cobalt Base Superalloys and the Effect of Remelting on Microstructure and Chemical and Physical Behavior
, M.Sc. Thesis Sharif University of Technology ; Yoozbashizadeh, Hossein (Supervisor)
Abstract
Because of the importance and value of Superalloy, In this research has been treid to remelting scrap of gas turbine blades cobalt based Superalloy X-45, In order to restore it to the cycle of consumption. For this purpose, scraps were remelted under different conditions, for example changing the atmosphere, changing slag composition, changing type of the furnace for remelting and changing time of remelting process. Then in order to investigate effect of the above factors, microstructure were studied by optical microscope and Scanning Electron Microscopy (SEM) And also in order to investigate changings of element composition, chemical analysis were examined by atomic absorption analysis and...
Dealing with feature interactions for prismatic parts in STEP-NC
, Article Journal of Intelligent Manufacturing ; Volume 20, Issue 4 , 2009 , Pages 431-445 ; 09565515 (ISSN) ; Xu, X ; Lazcanotegui, I ; Sharif University of Technology
2009
Abstract
Determining the precedence of machining features is a critical issue in feature-based process planning. It becomes more complex when geometric interaction occurs between machining features. STEP-NC, the extension of STEP (ISO 10303) standard developed for CNC controllers, is a feature-based data model. It represents all the geometric and topological product data minus feature interactions. In this paper, machining precedence of interactive and non-interactive STEP-NC features is discussed. Local and global precedence of machining features are defined on the basis of geometric constraints, such as geometric interaction of features and feature approach face and technological constraint such as...
Experimental Investigation of Mechanical Behavior of Structural Concrete with Combination of Waste Glass and Silica Fume
, M.Sc. Thesis Sharif University of Technology ; Khaloo, Ali Reza (Supervisor)
Abstract
Concrete is the second most structural material in the world. So attention and promotion of the concrete mix design with respect to variable issues and requirements, is very important. On the other hand, these days environment and its pollution has become very popular discussion. Waste-glass which is produced by human products is one of the environmental pollutants. In this thesis it replaces some aggregate in concrete and it can reduce the level of this material in the world. Also we study effects of silica-fume as cement replacement and properties enhancer in our concrete mix design and see how it can ...
Strengthening RC Slabs under Various Loads and Boundary Conditions Using FRP Composites
, M.Sc. Thesis Sharif University of Technology ; Khaloo, Ali Reza (Supervisor)
Abstract
In recent decades the use of FRP materials for strengthening structures has been developed extensively, thanks to their high strength, sufficient stiffness, high durablity, and ease of use. A great deal of research has been conducted on strengthening reinforced concrete beams and columns with FRP composites. By contrast, not many researches are performed on slabs, especially two-way slabs. In these few researches, the loading and boundary conditions are limited to simplest ones. Therefore, in this thesis, the focus of attention is on strengthening reinforced concrete slabs under various loads and boundary conditions using FRP composites.
In this thesis, first, FRP composites and their...
In this thesis, first, FRP composites and their...
Selecting a Sustainable and Resilient Supplier in Cold Supply Chain Using Grey Multiple Criteria Decision Making Techniques
, M.Sc. Thesis Sharif University of Technology ; Hajji, Ali Reza (Supervisor)
Abstract
Supplier selection is a strategic decision that has a key impact on the success of the supply chain. Due to the nature of goods and storage conditions in the cold supply chain has a great impact on environmental pollution compared to other chains, and it also has the possibility of disrupting the chain due to the importance of temperature and time conditions. Currently, due to the spread of international pressures on the observance of environmental and social principles, the issue of choosing a sustainable supplier has been raised. Also, the expansion of supply chains has caused the challenges and risks faced by supply chains to expand and disrupt the chain, so the decision of supply chain...
Response of Curved RC Shear Walls Under Cyclic Loading
, Ph.D. Dissertation Sharif University of Technology ; Khaloo, Ali Reza (Supervisor)
Abstract
Reinforced concrete (RC) shear walls with a curved cross-section are appealing structural elements to architects and engineers due to the aesthetic and structural advantages. Owing to the paucity of decent experimental research on curved RC shear walls (CRCSWs), the seismic response of these structural elements is essentially unknown. In that regard, this study includes research on a high-demanding type of structural element, which has found its application in North America, Europe, Asia, and to some extent in the Middle East with relatively no design specifications and laboratory research, structural analysis, and design methodology. Therefore, in order to provide an insight into the...
Optimal Batch Production for a Single Machine System with Rework
, M.Sc. Thesis Sharif University of Technology ; Haji, Ali Reza (Supervisor)
Abstract
This research attempts to develop the optimal solution for an inventory problem consisting of a single machine which produces items some of which may be defective. We assume that no shortages are allowed and all defective items are to be reworked. Setup cost for rework and waiting time of defectives are considered. This research consists of two different parts. In the first part we consider two different policies where in the first policy in each cycle after the regular production the machine is setup for the rework of defectives of the same cycle. In the second policy several cycles constitute a period. All the defectives produced in the period are reworked in the last cycle of that period....
Improving the Reliability of Energy Harvesting Wireless Sensor Networks
, M.Sc. Thesis Sharif University of Technology ; Ejlali , Ali Reza (Supervisor)
Abstract
Energy harvesters are used in today’s Wireless Sensor Networks (WSNs) to harvest the energy from the environment. One of the important advantages of the energy harvesting sensor networks over battery-operated sensor networks is that the use of the energy harvester prolongs the life time of the nodes, while a battery-operated node becomes useless once its energy runs out. Although an energy harvester can provide a supply source with a lifetime much greater than a battery, the amount of available energy for an energy harvesting system is a random variable and is not as predictable as the energy of a battery. This unpredictability may cause reliability problems. In order to solve the existing...
Gaining Competitive Advantage through Marketing Strategies in Container Terminal: A Case Study on Shahid Rajaee Port in Iran
, M.Sc. Thesis Sharif University of Technology ; Miremadi, Ali Reza (Supervisor)
Abstract
The competitiveness of a port convinced shipping lines and shippers with a significant basis in selecting a port. Port authorities and port operators can make use of the competitive advantage as a parameter for counter measures by grasping the advantages and disadvantages of the ports and be a prime factor of opportunities and threats of the ports. Ports have a significant role in today’s networked business environment. They are being regarded as hubs that are part of various logistic systems. The very essence of a seaport is to link maritime networks and land network. These networks for the port are means of analyzing its competitiveness. A port overall competitiveness is determined by it’s...
Energy Management in Energy Harvesting Wireless Sensor Nodes
, M.Sc. Thesis Sharif University of Technology ; Ejlali, Ali Reza (Supervisor)
Abstract
Wireless Sensor Networks have become widespread because of their flexibility, applicability and ability to precept data with high accuracy. However, the most limiting factor in their usage is the amount of available energy in nodes since energy depletion in a node means that it is dead, therefore many efforts have been done for optimum energy management in Wireless Sensor Networks. In many cases, the key solution to prolong the network lifetime is load balancing. In this way, all the nodes will die (approximately) together and the lifetime of network will be maximized. Load balancing can be implemented in all layers from physical layer to application. It should be noted that it is not always...
An Experimental Study of the Effects of Sweep Wing on the Boundary Layer of 2D Wing
, M.Sc. Thesis Sharif University of Technology ; Soltani, Mohammad Reza (Supervisor) ; Davari, Ali Reza (Co-Advisor)
Abstract
The behavior of boundary layer under the effect of the sweep angle is considered. The measurements were performed by a pitot tube rake. Three models with various sweep angels at angles of attack -2, 0 and 2 degree were tested. Both tip and root of all wings were closed by flat plates in order to prevent the flow to roll-up. However the flow field on the wing was still three-dimensional because of the sweep angle. The velocity on the wing has two components; longitudinal and lateral. The cross flow emerges due to the non-equilibrium of pressure and centrifugal forces. The velocity profiles showed that the magnitude of cross flow was stronger near the leading edge of the wing. The cross flow...
Fabrication and Characterization of ZnO Composites Nanofibers by Electrospinning Method for Photocatalytic Application
, Ph.D. Dissertation Sharif University of Technology ; Moshfegh, Ali Reza (Supervisor) ; Pourjavadi, Ali (Co-Advisor)
Abstract
In this research we focus on study and fabrication of ZnO composite nanofibers by electrospinning method for photocatalytic application. The most important challenges in the field of photocatalyst are photocatalytic activity under the visible light and efficiency enhancement. ZnO is a wide band gap semiconductor and it is not active under the visible light. In Iran, we have more than 300 sunny days in a year. Therefore fabrication and application of photocatalytic material with activity under the sun light that contained 40% of visible light is so vital in our country. In the first part of this project, ZnO-CNT nanofibers were fabricated and carbon doped in the crystal lattice of the ZnO....
The Exploratory Study of Customer Satisfaction & Loyalty in Private Access Provider (PAP)Companies: ADSL Internet Case in Iran
, M.Sc. Thesis Sharif University of Technology ; Miremadi, Ali Reza (Supervisor)
Abstract
Internet and the market based on this new product and service has penetrated in all aspects of today’s modern life of human being. After invention of this market each day a new innovation revolutionized this market and industry. High speed internet based on ADSL technology was one of these innovations. The high-speed internet service has achieved a remarkable increase in penetration in recent years. In order to survive in this competitive market, companies should continue to improve their service performance. The high level of service performance is believed to be an effective way to improve customer satisfaction and loyalty. In recent years, the high-speed internet service, based on the...