Sharif Digital Repository

Design of complex systems requires different challenges to be met simultaneously. Yet the current methods lack a sound theoretic framework and thus designers normally rely on heuristic or empirical methods; based on available experiences. Such approaches to the system design entail both technical and business risks and subsequently increase the probability of long-term problems. In this research, along with the theoretical framework of the systems design concepts, we discuss number of important models. The main concentration of the work, however, is to; somehow, correlate Axiomatic Design Matrix (ADM) with Design Structure Matrix (DSM). Here we exploit mathematical model based on sets and by... 

Numerical study of the interaction mechanism of the premixed flame and the acoustic field is performed in this work. The geometry similar to those used in experiments, is a two-dimensional tube in which flame travels form open end towards the closed end. The numerical study is done using PPM method. Results show that the shape and speed of laminar flame is strongly affected by the induced acoustic field. Stronger interaction is observed in the closed-end tube with no slip boundary conditions. The effect of the Lewis number on the interaction mechanism is also investigated. Premixed flame- accelerated flame – interaction of flame and acoustic field  

Translation quality assessment (TQA) as a systematic field of inquiry has been under scholarly investigation over the past decades. In spite of the challenges appeared in the path to success, theoretical and practical developments have already been made in translation studies. One of the unsettled and challenging problems concerning translation assessment, yet, is the subjectivity that is inherent in the process of scoring test-takers’ translation performances. In the absence of any granular objective criteria which includes all the subcomponents of translation as a multi-layer rather than unitary construct, the raters inevitably bring their intuition and will to the act of measurement.... 

Knowing the location and time of oil accidents and trying to track the pollution caused by these accidents is very important for the purpose of monitoring and protecting the environment. The occurrence of large oil spills in the marine environment can have serious environmental, social and economic consequences. In this research, oil spills in the Persian Gulf were first identified using remote sensing method and Sentinel-1 satellite images. The images of this satellite were called for the processes needed to identify oil spills in Google Earth Engine space. After detecting the oil spills, it is necessary to determine the duplicate spills and remove these types of spills, as well as estimate... 

Nowadays we are witnessing the emergence of machine learning in various applications. One of the key problems in data science and machine learning is the problem of dimensionality reduction, which deals with finding a mapping that embeds samples to a lower-dimensional space such that, the relationships between the samples and their properties are preserved in the secondary space as much as possible. Obtaining such mapping is essential in today's high-dimensional settings. Moreover, due to the large volume of data and high-dimensional samples, it is infeasible or insecure to process and store all data in a single machine. As a result, we need to process data in a distributed manner.In this... 

Nowadays, despite the special position of power electronic converters in the world, and the fact that they become an integral part of human life, still in the wake of a serious necessity the development process has not stopped and the increasingly fast pace, it opens up new horizons. This important necessity emerges from the environmental concerns regarding consumption of fossil fuels and their limited and imbalanced distribution which can be effectively addressed with the use renewable energy systems. By improving the quality of the semiconductor switches and offering new topologies in different functions as well as using new control methods, scholars try to develop enhanced converters in... 

In this thesis, we focus on some internal organization issues of the supply chain; in particular, we analyze some network design problems which are typical of producer companies. The aim is to optimize the flow of goods through the literature distribution network, from the plants where the goods are produced (supply points) to the demand points, which are essentially distributors such as wholesalers or retailers. The system addresses a class of distribution network design problems, which is characterized by multiple product families, a central manufacturing plant site, multiple central warehouses and distribution center, and retail outlets (customer zones) which demand multiple units of... 

The purpose of this research has been measuring how much studied companies use different levers of controls. Management control system has been described as the system which ensures the organization about implementing its strategy (Antony, 2004; Simons, 1995). In this research we chose Levers of Control framework (Simons, 1995) as the proper model to describe management control systems in organizations. Using related literatures, we developed a questionnaire to measure how much different organizations use each levers of control. The proposed questionnaire was distributed in three businesses with different Value Creation Logics (Stabell & Fjeldstad, 1998), to provide a ... 

Popular usage of composite materials in aerospace, civil and defense industries in the last decades has been the cause for paying more attention to optimization of composites tailoring. Due to inherent complexity of composite problems, i.e. discrete nature, complex interrelationship of design variables, existence of so many local optimum points, and etc., gradient base methods of optimization are found to be incapable and as a result using other powerful methods seems inevitable. Nowadays Genetic algorithm (GA) as an evolutionary technique is used for tackling composite problems. The success of a genetic algorithm can be quantified by estimating the cost, time required and the quality of... 

Today, the correct management of construction projects in IRAN's water industry has become a severe concern for its managers. Construction projects of the water industry constitute a considerable part of the country's construction industry. Several significant Issues such as operation management, water industry projects, correct management of resources, crisis management in the water industry, increased productivity and useful life of structures, increasing productivity, and preventing water loss are among the determinative challenges in construction projects in Iran. One of the new methods for the correct management of the life cycle of projects in this area is the use of Building... 

The distinction between SOEs and private firms in access to loans is essential from the viewpoint of policy-making. This distinction is more crucial when we know that the difference is caused by factors other than natural market forces and has emerged merely by government ownership. In this paper, we investigate a unique intervention in privatization and identify the causal effect of government ownership on access to loans. In this respect, we study Sahamedalat in Iran by using DID approach and estimate the effect of giving up the treatment firm's cashflow right on the amount and composition of the loans. The results show the intervention significantly decreases the long-term loan of the... 

Nowadays, concerns about the reduction of fossil fuels and environmental issues, have made renewable resources more important. Among these resources, photovoltaic (PV) systems are more popular than others, due to their environmental compatibility and unlimited availability of sunlight. Increasing the penetration level of PV systems in electricity networks presents various technical and control challenges such as voltage and frequency variations; and protection and harmonics issues. In this thesis, voltage rise problem due to reverse power flow in distribution feeders is discussed. This is one of the main obstacles to the expansion of these resources in distribution networks.Various solutions... 

With the progression of technology demands for novel method of heat cooling is increased so the old method of cooling such as heat removal by air stream with force convection and even single phase method was not sufficient for today’s industry need. Nowaday, spray cooling method which belongs to two phase cooling method is one of the most popular method. In this study two method of spray cooling: spray cooling with flow blurring nozzle and electrospray cooling were investigated. For both method, at first the physics of phenomena and morphology of spray is studied experimentally then the efficiency of heat removal in each method is evaluated by the assessment of variation of temperature and... 

Well stimulation techniques are used to increase the productivity of oil and gas wells. One of the effective well stimulation methods, is matrix acidizing. During matrix acidizing, acidic solution is injected into the formation at pressure below the formation fracture pressure. Most of the time, acid needs to be reached to low permeability layers for more efficient damage removal. Divertors are used for diverting acid from high permeability to low permeability layers.Successful performance of a viscoelastic acid during an acid job, is highly dependent on the surfactant rheological properties. For a betaine viscoelastic surfactant, we have studied the effect of different parameters on the... 

Cable-driven robots are referred to as parallel robots actuated with cables. In fact,in such robots rigid links are replaced by cables, which may be extended to desired lengths without making mechanism much heavy. This robot possesses a number of unique properties that makes it suitable for many industrial applications. The main factor which makes cable robots analysis different from other parallel robots is the incapability of cables to push objects. Hence, obtaining the workspace of a cable robot is one of the most important subjects associated with this type of robot.The goal of this thesis is to design a spatial translational cable driven robot, which may be used for object handling. For... 

Uncertain fuel prices and also global climate changes are accompanied by some state initiatives such as renewable portfolio standards (RPS). This has caused a fast growth in the amount of renewable energy installed worldwide especially wind energy over last decades. However, the intrinsic characteristics of wind farms output power, i.e. intermittency and volatility of wind speed along with being non-dispatchable in output generation of wind turbine raises many new technical and financial challenges for power system operators and planners. Up to these issues, large level of wind power penetration causes a growing concern in wind energy curtailment issue which the wind farm’s operator may be... 

A prismatic high temperature gas-cooled reactor (HTGR), which is a graphite moderated, helium-cooled reactor, is a promising candidate for next generation nuclear power plant in that it enables applications, such as hydrogen production or process heat for petrochemical by supplying heat with core outlet temperatures as high as 1000°C. A Thermal Hydraulic Analysis Code (THAC) for gas-cooled reactors has been developed. THAC implicitly solves heat transfer equation of fuel, graphite block and helium. Three types of fuel pins were considered; solid fuel pin, fuel pins with inside holes and annular fuels with coolant flow from its inside and outside surfaces. THAC predicts axial and radial... 

A triple antibiotic mixture (ciprofloxacin, metronidazole, and minocycline) has been used for dental root canal medicaments in pulp regeneration therapy. However, tooth discolorations, cervical root fractures, and inadequate pulp-dentin formation have been reported due to the triple antibiotic regimen. Therefore, antibiotic containing scaffold has been developed to minimize the clinical limitations and maximize a natural healing process in root canal infections. The ideal controlled release drug device should have the following characteristics. It should not degrade inside the root canal and it should be easily inserted into and removed from the root canal. In addition, the drug should be... 

Self-regulated learning, though having swept educational psychology's literature like a tidal wave (Boekaerts, 1999), and also, compared to other constructs such as metacognition and learning strategies, has remained comparatively uncharted in L2 research. One preliminary step to chart this concept is to develop questionnaires for it. With these and other things in mind, the principal purpose of this study was to develop a questionnaire in English and Persian to measure self-regulated language learning capacity and behavior of Iranian EFL learners. The development of the questionnaire was guided by two pilots (412 participants), content validation through expert judgment, cognitive...