Sharif Digital Repository

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.... 

Determining the best location for new wells is a complex problem that depends on reservoir and fluid properties, well and surface equipment specifications, and economic criteria. Various approaches have been proposed for this problem. Among those, direct optimization using the simulator as the evaluation function, although accurate, is in most cases infeasible due to the number of simulations required. This study proposes a hybrid optimization technique (HGA) based on the genetic algorithm (GA) with helper functions based on the polytope algorithm and the neural network. Hybridization of the GA with these helper methods introduces hill-climbing into the stochastic search and also makes use... 

The present research investigates the conjunction of two areas of pricing and negotiation techniques to find a relationship between price and other key factors such as quality, quantity, time, etc. and observe the overall effect of these factors on how to design and implement negotiations over price in B2B environment. The research presents a model to describe the process of negotiation and applies quantitative methods to rank negotiable scenarios. This set of scenarios, then is sorted in a triangular model of negotiation strategy and is used as a roadmap for negotiation. Furthermore, researcher evaluates effective tactics and their implementation to drive negotiation sessions based on... 

It is our purpose in this study to compare and analyze behavioral aspects of residential property valuation in Iran. More specifically, this research aims to explore the attributes that influence the value of residential property from the consumers’ and valuers’ perspective to determine whether valuers account for consumer behavior accurately. Finally, we investigate which variables operate at the lower end of the market, as distinct from those influencing the value of higher priced property. The core methodology underpinning the measurement of buyer and valuer behavior is the use of survey analysis. The identification of variables employing a two stage process forms an initial but critical... 

Statistics is an essential part of decision making and management in all organizations if the needed information is correct and updated. Due to lack of suitable information systems, it needs rework and spend extra time to gather information. Information Technology is used to summarize organizational information. It supports management of organization to make decision for strategic planning, tactical planning and operational programming by creation, storage, retrieve and distribute correct information to managers. For implementing these systems, there are many solutions. Selecting each one depends on conditions and potentials. Implementing integrated systems is expensive task therefore large... 

Considering the daily growth of industries in international market competition and the necessity of investment in related infrastructure development, determining the priority of industries in order to strengthen or support of these industries, seems as an inevitable issue, so for the purpose of making proper decisions in an optimum way, we must use scientific decision making methods. This study evaluates the priority of industries in Iran and comparison of them. Therefore, according to the international standard classification of economic activities (ISIC), two-digit and four-digit codes are specified for each industry. In addition, based on major economic indicators, the status of these... 

This thesis investigates various modulation recognition systems both in analogue and digital forms. We are looking for a recognition technique considering practical implementation issues. To recognize the modulation, the career frequency is supposed to be known and a bandpass signal is received. Besides, we investigate some digital Automatic Modulation Recognition (AMR) methods. The techniques based on the features of the signal have less computational complexity compared to Maximum Likelihood (ML) techniques; hence they are more desirable for practical implementation. In this project, analog modulations are implemented using C++ software. For the convenience of users, here, two graphical... 

Traditionally, supplier selection should simultaneously take into account numerous heterogeneous criteria and then is a tedious task for the purchasing decision makers. The global supplier selection problem is more complex than domestic one and it needs more critical analysis. It becomes especially complicated when quantity discounts are considered at the same time. Under such manner, most studies often formulate such a problem as a Multi-Objective Linear Programming (MOLP) problem, and then scale it down to a Mixed Integer Programming (MIP) problem to handle the inherited multi-objectives simultaneously. However, this approach often neglects to consider scaling and subjective weighting... 

In this research, the aim is to find the factors that can influence on the utility perception of both private buyers and experts. What's more, the share of each factor on the overall utility is derived by the use of AHP technique. The next step is to derive a model that contain all the factors seen by private and inexpert buyers., and their relative weight. At the next step, the aime is to complete the model by adding the factors not seen by all private buyers, but advised by residential apartment experts and their relative weight. The model should be able to rank different residential apartments, when the value of each factor is given for each ot the apartments.

 

Water resources planning and management projects are done in order to accomplish several goals. Moreover, social, environmental, political etc impacts of such projects increase the complexity of the problem of choosing the best alternative among others. The project of diversion of water form Zab Watershed into Lake Urmia Watershed is one of these projects which regarding water demands and problems in Lake Urmia Watershed and also Zab Watershed water resources that exceed its water demands has been considered. Therefore, after conducting research studies, five locations have been determined as potential places to build a dam on the Zab River and transferring its water to Lake Urmia Watershed.... 

The main objective of all managers of the economic organizations, manufacturing and industrial companies and service providers is to take steps toward improvement and effective use of different resources like workforce, capital, materials, energy and information. To attain the desired productivity, managers have to observe requirements such as establishment of a working organizational structure, effective implementation methods, safe equipment and tools, balanced working atmosphere and qualified human force as the most important factor. Therefore productivity culture should be publicized throughout the organization, and human force should be considered as the main component of this process.... 

Online voltage stability assessment is essential for preventing the failure in power systems. Voltage instability in power systems usually occurs in consequence of contingency situations or continuous load increasing or both of them. A new method for online voltage stability assessment using the data acquired from phasor measurement units (PMUs) and offline trained decision trees is presented in this thesis. The index of voltage stability margin (VSM) is used for security assessment and considering WSCC criterion, different operation points are divided in two classes: safe and unsafe. In order to obtain the voltage stability margin and generate the database, a new method which has been named... 

Decision making for planning a petrochemical plant is a difficult task, particularly when decisions are required to be made under constraints and different objectives. Final purpose of current research is to develop a reliable model for selecting limited petrochimal products among all potential alternatives under different constraints, considering two desired objective functions; Maximizing economic gain and minimizing safety risk. The powerful tool of multi objective decision making has been used for solving the proposed model. The developed model has been applied to Jam Petrochemical Company as a case study and the acquired results found to be successful.

 

Pavement maintenance and rehabilitation is an important problem in road pavement programming. Pavements experience significant distress over its life due to passage of vehicle (particularly heavy trucks), as well as abrupt variation in temperature (freeze and thaw). This would deteriorate pavements and reduces their serviceability. Rise of pavement maintenance costs places higher importance upon the need for maintenance programming. This study employs an evolutionary model to optimize the long-run benefit of the maintenance program. The model is stochastic in nature, and imbeds a Markovian decision procedure in the model to take into account such variabilities. The model is applied on... 

Key conservation organizations to meet customer needs and attitudes of SCM is not only the ultimate goal of customer relationship that the final product delivers, but a sequence of suppliers in this work considers the integration of organizations involved in the synchronization process material, and financial information to improve the competitiveness of the supply chain are examined. The proper functioning of the supply chain , a key role in achieving sustainable success of an organization and its profitability goals, especially. In this regard, the establishment of a system of supply chain performance measurement in continuous improvement of its performance is recommended. In each of the... 

Nowadays, Resource Capacity Management (RCM) is one of the main challenges for industries which have a limited capacity to meet the demands. Revenue Management (RM) is a technique that controls the supply, improves the quality of Capacity Management and maximizes the revenue. Supplying the products and services to different groups of customers is a decision making problem.While the classic RM techniques take into account only the expected revenue, preferences of decision makers strongly affect the results. In this study, utility theory has been proposed because the healthcare industries are usually nonprofitable and they are not highly focused on the revenue gained by their products and... 

The integration of renewable energy sources introduces several issues including islanding operation. Therefore, Islanding phenomenon should be detected by a fast and reliable islanding detection method. In this thesis an intelligent-based approach is proposed to detect islanding state for Photovoltaic (PV) and Doubly Fed Induction Generator (DFIG) units. Decision tree classification algorithm is chosen as weak classifier and by Adaptive Boosting (AdaBoost), detection accuracy is improved. 16 features are employed to construct feature vectors. Because of intermittency of renewable electricity generation, different states for PV and DFIG generation are assumed. Probable events are simulated... 

Nowadays, living in information era has forced us to face with a great deal of problems of which the input data is received like a nonstop endless stream. Intrusion detection in networks or filtering spam emails out of legal ones are instances of such problems. In such areas, traditional classification algorithms show function improperly, thus it is necessary to make use of novel algorithms that can tackle these problems. Among classification algorithms, decision trees have significant advantages such as being independent of any parameter and acting robust against outliers or unrelated attributes. Moreover, results of a decision tree are quite easy to interpret and extract rules from.... 

In Computer-Aided Process Planning, there are two ways of manufacturing called Variant Manufacturing and Generative Manufacturing. Variant Manufacturing is based on a data base from a part family for a project. The part family is made in a series of root sheets regarding the final form of the intended part. The data base is updated after the manufacturing of each part. In order to make the system intelligent, one can use the OPITZ coding system that specifies the geometrical form, geometrical details and part manufacturing operations in a 13-digit number. The aim of this research is to choose the best machining parameters according to time and cost, that, based on the basic principles of... 

The brushless DC Limited-Angle Torque Motor (LATM) has been widely used in area of aerospace equipment, robot drives, optical scanning systems and any drive systems that require limited motion, ranging from the simple ON-OFF servo valves to the accurate tracking of a reference signal. This paper presents the optimum design procedures of a brushless direct current limited-angle torque motor. According to a request from industry, a two-pole torque motor with a toroidal armature winding was designed based on analysis of magnetic equivalent circuit of motor structure, and using selected ferromagnetic material and rare-earth permanent magnets (PM). To select the best design solution and optimize...