Sharif Digital Repository

Various philosophical views on scientific models, in this research, are reviewed and criticized. From a syntactic point of view, a scientific theory is nothing but its models, and this is the theory that illustrates how the model is constructed. Pragmatic view, by adopting a pluralistic view, argue that the interpretive model provides the basis for the concretization of the abstract concepts of the theory, and it is possible that representational model is incompatible with the theory itself. The model works better than theory even in functions such as prediction, explanation and representation in some places. A group of philosophers believe that with the introduction of fiction discussion,... 

A novel SPME fiber was prepared using sol-gel technology with ethoxylated nonylphenol as a precursor and used for development of a headspace solid phase microextraction coupled with gas chromatography-mass spectrometry method for quantification of 13 priority polycyclic aromatic hydrocarbons in water samples. The fused silica is the material that has recently been used as a substrate in sol-gel works for preparation of SPME fibers. Given that its drawbacks such as breakability and fragility which make the work tedious and time consuming¬, in this survey stainless steel wires were chosen as a substrate for coating the sol-gel film on them. The fibers made from steel are vary sturdy and aren’t... 

As technology develops, the need of instruments which could be used for improving the rate and accuracy of the manufacturing increases. This makes the robots inevitable to use in most industries. Among the robots, cable-driven robots have special characteristics that increase the tendency of using them.Multi-body cable-driven robots are novel type of cable-driven robots that have advantages compared to single-body ones. Capability of use in rehabilitation applications, in which the different parts of human body have to move separately, is one of the advantages of multi-body cable-driven robots.The first aim of this thesis is to extend the tensionable workspace concept for multi-body... 

Structural health monitoring (SHM) has been motivated in aircraft and civil industries over the two last decades. Ultrasonic guided wave propagation technique is one of the best damage detection methods in airplane thin wall structures because of their large distance traveling and low attenuation.
In fact by efficient design of sensors pattern one can effectively pick up the changes that happen in propagated signals due to presence of any kind of structural damage. This could be effectively achieved by numerical simulation techniques like finite element modeling. To obtain a damage detection algorithm based on instantaneous baseline data, here, finite element technique is employed for... 

In this thesis, marx pulsed power generators are investigated. Due to very large magnitude of its output voltage and very fast rise time, Marx generator is the first choice in lots of pulsed power applications. A significant barrier in the implementation of this generators are the switches with witch the structure is made. The short magnitude nominal voltage and current of the solid state switches lead to use of Spark Gaps in which the determinative parameter of the switch to turn on, is its breakdown voltage. These switches have some limitations in repetition rate and turn off ability. However due to very high range of nominal voltage and currents, they are an appropriate choice for marx... 

Planning orders and inventory is one of the most important issues in the planning of petrochemical production. Considering the customization of this industry, orders planning includes a large part of it. Also, in order to reduce the great cost of inventory storage, planning to reduce inventory must be considered. In this regard, we intend to present a model with simultaneous consideration of orders and inventory planning in this research, the ability to decide on acceptance of orders and determine the level of production of products in conditions of uncertainty of demand with random trapezoidal demand in each period can be assumed. This model will practically play a key role in improving... 

The growth of road freight transport in recent years, in addition to positive effects, has also left negative externalities. Part of the negative effects such as environmental pollution and damage to infrastructure is exacerbated by the lack of capable transport companies and the low productivity of transportation systems. The government intervenes through regulatory scenarios such as restrictions and tolls to reduce the negative effects on the road transport market. But which scenario is more effective in improving the productivity of the current transportation structure and what will be the consequences? This paper introduces an agent-based micro-simulation to model domestic trucking... 

This paper presents five origin-destination (OD) flow estimation models using traffic sensors. The first model uses counting sensors data, the second model uses automated vehicle identification (AVI) sensors data and the third, fourth and fifth use combined data of counter and AVI sensors simultaneously. The first to fourth models are bi-level problems that the upper-level minimizes some objective functions where is the distance between estimated flows and observed flows. On the other hand, the lower-level problem finds user equilibrium (UE) flows pattern for estimated origin-destination matrix (ODM). The fifth model is a multi-objective problem, where a bi-level problem is solved for each...