Sharif Digital Repository

Decision-making about make or buy is one of important and strategic decisions. Any wrong decisions in this regard can cause high costs to organizations. About this make or buy decision, there is rich literature and experts of different scientific fields such as economy, sociology, industrial engineering, and management, etc. study about it. According to importance of make or buy decisions in research organization and self- sufficiency Jihad as a supportive organ from IRIB in order to make needed products of this organization, the main purpose of this research is to provide and present a conceptual framework to help make or buy decisions for this organization. The research method in this... 

In this research, inspired by the navigation system of insects, a method for extracting the navigation information required for an autonomous device is presented, with an information input section in the form of image processing using optical flow and an information processing section with an artificial brain structure. In this method, the information obtained from the optical flow is processed by the neural network structure and the navigation information needed to control and guide the autonomous device is obtained. There are several methods to estimate the optical flow between two frames, in this research, the DEQ-Flow optical flow estimation network, which is a method based on deep... 

In multi-agent systems (MAS), collective behavior of autonomous agents and complexities arisen by their interactions are studied, while they are exploited to solve real-world complex problems. Machine learning methods are frequently used for problem solving in MAS, because complexities in these systems prevent a programmer to thoroughly describe the agents’ behaviors and the rules governing them.Reinforcement learning (RL) is one of the most commonly used learning methods for intelligent agents,because it does not need a model of the environment and learns agents’ policies through trial and error.Conventional RL algorithms store and update utilities for every possible state in a table. One... 

Data collected from street networks show that travel time in urban street networks is a stochastic variable, whose range of variation increases with the congestion level. Work and school trips comprise the major part of morning peak volumes, whose common characteristic is that they need to be made on time. For this reason, these travelers are pessimistic in their route choice, and try to choose routes which are more reliable. Travel time standard deviation is one of the common measures for estimating travel time reliability that is related to properties of day-to-day travel time distribution on a particular route. Based on the empirical data collected from Tehran street network, this paper... 

Noise or noise pollution, is defined as an unwanted sound, produced mostly by motor vehicles in urban areas. If the noise exceeds its limit, adverse effects on users and citizens are expected. Thus the assessment of the noise level and its comparison with allowable values is mandatory. Traffic induced noise depends upon different factors such as traffic, weather, and, sound barriers. Noise pollution study has a long history all over the world. Many studies, mostly representing the outdoor noise pollution models, have been done in recent years. This paper presents an assessment of traffic-induced noise in a heavily traveled tunnel, locally referred to as Resalat tunnel, which is located in... 

In this thesis, we introduce a novel Artificial Intelligence (AI) system inspired by the philosophical and psychoanalytical concept of imagination as a ``Re-construction of Experiences". Our AI system is equipped with an imagination-inspired module that bridges the gap between textual inputs and other modalities, enriching the derived information based on previously learned experiences. A unique feature of our system is its ability to formulate independent perceptions of inputs. This leads to unique interpretations of a concept that may differ from human interpretations but are equally valid, a phenomenon we term as ``Interpretable Misunderstanding". We employ large-scale models,... 

In this research, non-isothermal annealing process at temperatures ranging between 400°C to 830 °C was investigated in warm and cold-rolled austenitic stainless steel 304L. First, the wide variety of austenitic to martensitic structure was produced by the multi-pass rolling process at room temperature -8 °C, 200 °C, and 280°C. The n exponent in Olson-Cohen equation was governed 2.83 after non-linear curve fitting to assess the fraction of deformation-induced martensite as a function of strain. Afterward, Abaqus/Explicit method was utilized to achieve the stored energy and plastic strains distribution through the thickness. Then, Cellular automata and Galerkin-finite element models were... 

The importance of New Product Development (NPD) projects has been realized more and more in recent years. Among different decisions to be made in NPD process, one of the most critical decisions is about the best time to launch new product(s). Due to existence of many internal and external influential factors, determining the optimal launch time is often too complicated and it is quite hard to systematically analyze it. Despite risky nature of NPD, risk considerations in determining the optimal launch time have not been addressed in literature due to the mentioned complexity. In this research, we developed a model that takes in to account risk considerations while systematically determining... 

Coreference resolution is an essential step toward understanding discourses, and it is needed by many NLP tasks such as summarization, machine translation, question answering, etc. Pronoun resolution is a major and challenging subpart of coreference resolution, in which only the resolution of pronouns is considered. The existing coreference resolution approaches can be classified into two broad categories: linguistic and machine learning approaches. Linguistic approaches need a lot of linguistic information for the resolution process. Acquisition of such information is an error- prone and time-consuming process. In contrast, learning approaches need less linguistic information and provide... 

Global climate change and anthropogenic impacts lead to alterations in the water cycle, water resource availability and the frequency and intensity of floods and droughts. As a result, developing effective techniques such as hydrological modeling is essential to monitor and predict water storage changes. However, inaccuracies and uncertainties in different aspects of modeling, due to simplification of meteorological physical processes, data limitations and inaccurate climate forcing data limit the reliability of hydrological models. Assimilation of new observations constrains the dynamics of the model based on uncertainties associated with model and data, which can introduce missing water... 

The magnetic MOF-based catalytic system has been reported here to be an efficient catalyst for running CDC reactions and synthesis of Triazole rings under optimal conditions. The robust MOF catalyst was built based on magnetic nanoparticles and HKUST-1 which further modified with thioacetamide and carbonization. The catalyst structure was confirmed by various techniques. Furthermore, the products’ yields were obtained in good to excellent for all reactions under mild conditions which result from superior activity of the synthesized heterogeneous catalyst containing Cupper. Also, the magnetic property of the MOF-based catalyst makes it easy to separate from reaction mediums and reuse in the... 

Drop formation from the tip of a nozzle and its motion in bulk fluid is an interesting and practical process which has widely turned researchers’ attention. Investigation into the governing physics and effective parameters on formation, deformation and motion of a drop increases the efficiency of the related industrial processes. Thus in the present study, in order to simulate this process, full Navier-Stokes equations solved by the Volume of Fluid (VOF) method in an axisymmetric domain using Fluent software as the solver. In this research, the effects of Weber number (the proportion of inertial force to surface tension force) and Ohnesorge number (which refers to the proportion of viscous... 

Sulfur components are one of the most important impurities in various petroleum fractions that cause many problems in refining and consumption. In this thesis, hydrodesulfurization process, which has an economical and environmental especial position in petroleum and other related industries, has been discussed. In hydrodesulfurization process, under specific operation condition, sulfur components are converted catalytically to the H2S in a fixed bed reactor. In this study dibenzothiophene, which is one of the most strength and complex sulfur components, is considered as the base component. A Langmuir-Hinshelwood kinetic equation is used to describe the reaction by using the commercial... 

Fractures of the shaft of the long bones-especially in femur and tibia- is one of the most common fractures. In past decades various methods have been suggested for induction, fixation and repair of these fractures. The main fixation method for shaft fractures of femur and tibia in adult patients is named “Intramedullary Nailing”. In this method, after inducing the fracture, the bone marrow is pulled out via a hole created in the proximal part of the bone. Then, a nail will go down through this empty space inside the bone. This nail will be fixed in to proximal and distal parts of fractures with some locking screws. This way, the part of fracture cannot move respect to each other and the... 

For observing the beauties of the sea, underwater vehicles are of the most appropriate equipment. In an optimized design of a vehicle, one should consider all applied forces and moments at all positions of the vehicle. Moving near the free surface is one of the positions of underwater vehicles. So, study on flow around a body moving near free surface is the subject of extensive research in marine hydrodynamic.
The aim of the current investigation is a scrutiny of the influence of free surface effect on the flow around underwater vehicles. For this purpose, finite volume method is used to simulate flow around an axisymmetric body near free surface. In this simulation, volume of fluid...