Sharif Digital Repository

We study the problem of experiment design to learn causal structures from interventional data. We consider an active learning setting in which the experimenter decides to intervene on one of the variables in the system in each step and uses the results of the intervention to recover further causal relationships among the variables. The goal is to fully identify the causal structures with minimum number of interventions. We present the first deep reinforcement learning based solution for the problem of experiment design. In the proposed method, we embed input graphs to vectors using a graph neural network and feed them to another neural network which outputs a variable for performing... 

Performance-based design (PBD) has been accepted as one of the most reliable design methods in the past few decades. PBD can overcome inherent deficiencies associated with force-based design (FBD) and has advantages over this traditional method. Various PBD methods have been developed, which Displacement-based design (DBD) has been considered as one of the effective design approaches of the PBD method. In this study, the Displacement coefficient method (DCM) is developed for stub-type integral abutment bridges (IABs). For this purpose, two coefficients are proposed to determine the target displacement of these types of bridges. Validation of this method by nonlinear time-history analysis... 

The world around us changes almost every second, so the economy in this world feels it more by every single minute. When we look at the organizational structures, they experience lots of things for keeping the companies competitive and the human resources have the main role among the other stimulating factors.The human resource management and its improvements have done a lot in this century to organize and manage the human problems in organizations. After that those companies that had more effective strategies become on top of this important management system. By changing fast the work models companies experience more and immediate changes that may not happen even through the years. In this... 

In today’s industrial world production is considered as a competitive weapon. This has caused many companies active in this field to move towards creating competitive advantage to reduce costs of design, construction and increase production. In particular molding as one of the main industries is among the most economical technological resources of each country. About 50 to 70 percent of the price of a production operation is spent of the strip of sheet by pressing; thus the proper design of a strip of sheet has a great impact on the mold design. Today, in most sectors of the industry there is a need for cutting and packaging of products and form molding and glass cutting to fitting the... 

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,... 

A basic highway design problem is to find the most economical alignment connecting two given end points based on topography, soil conditions, socioeconomic factors and environmental impacts, while satisfying a set of design and operational constraints. The cost function complexity and numerous limitations such as highway design criteria have made this problem a NP-hard one. In this study, a swarm based searching algorithm has been applied to a three dimensional highway alignment optimization model. The spatial data has been exploited from a GIS databases using a heuristic swift approach. In addition, the majority of cost items that depend on highway design have been extended in a practical... 

Deteriorated old urban neighborhoods usually have no access to appropriate municipal services, and have small-sized buildings, densely populated areas, and earthquake-prone structures. Residents in these areas do not have the will and financial ability to renovate their aged properties. A questionnaire survey of the citizens living in the deteriorated areas of the City of Tehran showed that 80% of households do not have a positive monthly financial balance and cannot afford the cost of reconstructing their properties. Serious drawbacks of previous attempts to renovate deteriorated areas, including lack of adequate government funding, and adding to the dependence of local citizens on... 

Growing concerns towards social and environmental issues besides economic in supply chain causes that the sustainable supply chain become one of the most important concepts in a supply chain. Likewise, a supply chain network design which is profound influence on long-run economic, environmental, and social decisions is one of the key and strategic topics in a supply chain. In this study, we represent an integrated approach for a three-layer sustainable supply chain network design with routing and different transportation modes, the objectives of which are minimizing total costs, a minimizing 〖CO〗_2 emissions of transportation, and maximizing total values of social purchasing. In this... 

One important problem in all, particularly in developing countries, is shortage of funds to invest in infrastructure projects. One way to lessen this difficulty is to benefit from the private sector participation in this respect. Build-Operate-Own-Transfer (BOT) is a Public-Private-Partnership (PPP), in which the private sector invests and builds a (e.g. road) project, operates it for a specified period of time to collect the tolls to return the investment cost plus the specified attractive rate on it, and then transfer it to the public sector. This research, which is a continuation of previous endeavors in this area, formulates the problem, discusses the multiplicity of the solutions, and... 

RT-level techniques are one of the most important categories of techniques employed for decreasing power consumption in digital systems. These techniques are usually applied in the HDL description of the system, however some of them are applicable automatically by the synthesis tools. Some of the most commonly used RT-level techniques include Operand isolation, Clock gating, Concurrency & Redundancy, Pre-computation and Pipeline for low power. However these techniques have been mostly employed in ASIC designs, and FPGAs have scarcely been addressed. Application of these techniques on FPGAs might need special considerations, since resources on FPGAs are inherently different than their ASIC... 

Most of current the MAC protocols for Wireless Sensor Networks (WSNs) concern about energy efficiency rather than low latency. The main source of energy consumption in the MAC layer is idle listening, and most of these protocols use duty cycling for reducing energy consumption. But duty cycling method increases packet delivery latency. This problem is very critical in real time applications where packets should meet their deadline. There are some solutions for this problem. For example a node forwards data packets multi hop away instead of one hop in a single cycle. In this research, an efficient cross layer MAC protocol for real time applications is proposed. In this protocol multi hop... 

In this thesis, we propose a QoS-aware routing algorithm for multimedia streaming that uses cross-layer information (application layer and physical layer) in Wireless Multimedia Sensor Networks (WMSN). Our goal is to use cross-layer information to route video packets efficiently and deliver a higher quality video in streaming applications. Our QoS-Aware Multi-Path Selection (QAMPS) method is based on multi-path multi-priority selection algorithm that uses Two-Phase geographic Greedy Forwarding (TPGF) as a routing algorithm. The proposed method guarantees QoS by splitting video streams into I-frames, P-frames and B-frames in the application layer and passes them to the network layer for... 

In this work, we propose a metamodel-based simulation optimization algorithm using a novel hybrid sequential experimental design. The algorithm starts with a metamodel construction phase in which at each stage, a sequential experimental design is used to select a new sample point from the search space using a hybrid exploration-exploitation search strategy. Based on the available design points at each stage, a metamodel is constructed using Artificial Neural Network (ANN) and Kriging interpolation techniques. The resulting metamodel is then used in the optimization process to evaluate new solutions. We use Imperialist Competitive Algorithm (ICA) which is a powerful population-based... 

Road network expansion is a well known problem in the world, particularly in developing countries. One approach in financing this development is to charge the users for the services rendered. Recent studies prove the merits of private sector participation in road investment and revenue collection. Public sector may cooprate with private sector in permitting it to build the roads, operate and maintain them for certain period of time, while taking advantage of the revenues collected. The road will, then, be transferred to the public sector when that period of time is over. This study presents an extension to a previous model in this area. It presents a bi-level programming network design... 

A simple control system contains at least an actuator, a controlled link, and a foundation. These structures are not ideally rigid, this flexibility can appear willingly or unwillingly in any parts of the system or the connections between them. As a consequence of this flexibility, the movement of the controlled part will fluctuate unintentionally. In this thesis, a control system with rigid controller and flexible torsional base is investigated and controllers are designed and compared to reduce these unwanted vibrations. Finally, by implementing the controllers on the constructed system, the experimental results are obtained and compared with the analytical results.To fabricate the... 

The purpose of this project is designing a controller for a floating offshore wind turbine to exctract maximum power from wind energy in the first operating region of wind turbine. The NREL 5 MW OC3-Hywind floating wind turbine with BARGE platform will be used for this project. By using Turbsim software, proper wind profile for the first operating region of wind turbine will be produced. This profile will be excecuted for the FAST software that is simulates the mechanical part of wind turbine. By implementing the doubly fed induction generator in Simulink enviroment and designing the controller for doubly fed induction generator, the desired torque for maximizing the exctraction power of... 

Advanced control techniques are required to achieve a cost-effective and reliable use of the wind power generation. The wind turbines are generally controlled based on two control objectives: the turbine protection and the generation of acceptable power for the utility grid. These objectives are achieved if the control inputs are applied based on appropriate control logics. In this work, a nonlinear multivariable model of the wind turbine with a DFIG generator is considered. The rotor speed and the d-axis rotor current (as the control outputs) are controlled via manipulation of the two generator voltages (as the control inputs) in low wind velocity condition. For high wind velocity, the... 

Due to the destructive effects of sudden and adverse changes in acceleration on the human body, drivability control has a particular importance in the automotive industry. Driveability control makes car occupants feel a smooth and comfortable driving, and it will play a vital role in the competition between companies to provide a good product with optimal driving quality.In this project, the aim is to achieve a smooth acceleration curve in a vehicle equipped with a manual transmissions. The meaning of smooth acceleration curve is to reduce jerk and shock caused by inappropriate driver behaviors and to control the car's torque and acceleration to a desirable level. In this project, first, the... 

The main goal of this research is to reduce aircraft design cycle period, by reducing the necessary number of design cycle iterations. The Design cycle period is one of the main characteristics of the design process and design cycle iterations play a major role in the design cycle period. To achieve the above mentioned goal, we present a mathematical model of iterations for the aircraft design process. This model describes the design coupled tasks as a discrete-linear time invariant dynamic system. This model also helps identify tasks which are the most important for generating iterations. This new method basically helps break information cycles that create iterations among important tasks....