Sharif Digital Repository

The ever increasing usage of modified binders in road construction requires that the effect of different modifiers on the performance characteristics of the asphalt binder be determined through laboratory testing. The current Superpave protocol for performance grading asphalt binders has proven to be insufficient to properly characterize modified binders, thus researchers have searched for other testing methods to complement or possibly replace some of the Superpave tests. Most notable are the time sweep test for fatigue resistance, the multiple stress creep and recovery test (MSCR) for rutting resistance and the direct tension test (DTT) for low temperature cracking characteristics. In the... 

Nanopositioning is a technology for moving a target object within nanometer (10-9 meter) resolution. Nowadays nanopositioning stages have emerged as an important technological advancement in hi-tech applications, including scanning probe microscopy, lithography, nanometrology, fabrication and assembly of nanostructures and beam steering for optical communication systems. To achieve nanometer resolution the stage must focus on a few tens of micrometers travel range. The combination of piezoelectric actuators and monolithic compliant mechanisms can provide a smooth motion without friction, wear, and backlash. So, piezo-driven compliant mechanisms are used widely in nanopositioning systems. The... 

Today, for construction of UAV, designers are interested in and trying for substitution of composite material instead of metal. They would rather use composite structures due to lower costs of construction, availability, along with high ratio of strength to weight of this material, while metal structures are mainly rare and too expensive for construction of UAV. For instance, unavailability of aluminum metal and complicated methods of construction of aluminum wings with using of special tools, justifies using of composite with easier construction, abundant, and cheaper materials. The main goal of this project is redesign of aluminum wing of a jet engine UAV, In fact, by doing some structural... 

Semi-automated Continuous Speech system deals with collecting corpus speech. It has very different problems in various natural languages because of different types of speech, and collecting speech corpus containing continuous word is very time-and- cost consuming. To overcome this problem, human-based computing techniques are proposed to collect speech corpus. In this thesis, we describe influencing factors in collecting steps of continuous speech and provide a description of human-based techniques to solve problems specially collecting of continuous speech. To collect speech corpus using human-based techniques, a game has been used so that speech corpus of web users are collected during the... 

In this research, a pricing-inventory model with multiple interdependent products and stochastic demand is studied. In the relevant literature, there are many researches that are related to optimize the inventory or price independently and also optimizing joint inventory and pricing for single product. But joint optimization of inventory and pricing for multiple interdependent products is relatively new and still there are many potential research gaps in this area. We develop the model with additive and multiplicative demand uncertainty. Then we develop a genetic algorithm and tune its parameters to solve the models. We investigate the efficiency of proposed GA. Results were relatively good.... 

The ambiguity in the meaning of scientific explanation has caused the philosophers to use different criteria for differentiating it from other explanations. One of the most important of these criteria is Salmon’s criterion. According to Wesley Salmon, a scientific explanation is an objective issue and it is far beyond descriptive knowledge which can be found out about the world. The index provided by Salmon for explanation as a scientific interpretation is based on two principle foundations: 1. Statistical relevance 2. Causal relation. It would be a key to understand the world better. In this paper, first, we will argue that the explanation has both objective and subjective components and... 

As nuclear energy continues to be used as a useful energy resource, waste management, especially management of high-level nuclear waste (HLW), will always be a major concern, as the future generations should not be deprived of the valuable benefits of this energy. Vitrification of liquid high-level radioactive waste (HLW) has received greater attention, worldwide, than any other high-level waste solidification process. The high solubility of HLW in borosilicate glass, the controllable temperature of this type of glass and its low leaching rate in repository environment, have introduced borosilicate glass as a suitable host for HLW immobilization. In this project, the immobilization of the... 

In this research, the instability analysis of single-walled carbon nanotubes (SWCNTs) and graphitic shells conveying fluid is investigated based on the molecular structural mechanics. Using the reduced order models for fluid and structure, the dynamic behavior of carbon nanotubes (CNTs) conveying fluid is accurately modeled via a few number of lowest flow modes and natural frequencies and mode shapes of CNTs structure. In addition, the boundary element method (BEM) is used to model the potential flow. The molecular mechanics (MM) model is applied to modal analysis and driving the natural frequencies and mode shapes of SWCNTs. The effect of chirality on flow-induced instability is taken into... 

Double channel and coreless induction furnaces are used extensively in many processing industries due mainly to their good heating efficiency, high production rate, clean working environments and relatively low operating costs. The study of heat transfer treatment and evaluation of the heat losses of these furnaces becomes an important issue in melting industries. In this dissertation, a heat transfer analysis will be performed for an induction furnace and heat losses by conduction, convection, Eddy-Current and Hysteresis in a furnace structure, and radiation from the body of a specific induction furnace will be modeled considering the symmetry of the furnace chamber. The models presented in... 

Leakages in the transmission pipes include a large proportion of water loss. Scarcity of fresh water in one hand and high costs to compensate for drop in pressure and flow lines, on the other hand, detection and location of leaks have been important. This phenomenon can also cause a lot of damage to the urban contextures. This thesis considers the leakage in tubing buried in the soil by means of a floating robot. Since the rate of leakage, specifies the requirement to perform maintenances, In addition to finding the leakage, an overall estimate of the amount of leakage is desired.Since non-destructive leak detection is desired, the mechanical-magnetic sensor is designed. First, for the... 

In this thesis, Model reference adaptive control in fractional order systems was discussed. Various types of this problem can be introduced based on fractional order dynamics in system equations, reference model equations or adaptation laws, which some of them play more important role in real-world applications, also some of them have more complexity in governing mathematical equations and in stability analysis. Fractional order dynamics were recently used in many real-world applications like model reference control, Chaos synchronization and Chaos control, so studying adaptive control in this fields, could be important. Nowadays, Model reference adaptive control was used in many industrial... 

This investigative study intends to identify and characterize bitumen from seven Iranian bitumen production plants according to the Superpave Performance Grading (PG) system, conventional classic tests, and chemical separation tests. The study then compares the identified performance grades with the thirteen performance-grade binders required for specific climatic zones in Iran. It is observed that the variety of available binders is not adequate to fully cover the required PGs. Blending was initially considered as a suitable and economic method for production of the missing performance grades. However due to similar rheological properties of bitumen samples, resulting in nearly identical... 

Rutting is a primary cause of premature deterioration of asphalt pavements and modifying asphalt binders is a common way to improve binder characteristics and field performance. Two types of parameters are used to characterize asphalt rutting. One type includes binder parameters such as zero-shear viscosity and the Superpave rutting resistance index (G*/sinδ) derived from oscillatory loading tests such as the dynamic shear rheometer. The other type is derived from static and repeated loading creep tests on mixtures and binders. Researchers have pointed out that these parameters can rank modified binder and mixture rut susceptibility differently. In this study the rutting resistance of... 

Bitumen ageing is one of the principal factors causing the deterioration of asphalt pavements. Ageing is a complex process that is affected by different parameters.With the rapid growth of modified binders in road paving applications over the past twodecades, it is important to study the ageing properties of these binders. A number of laboratory methods are used tosimulatethe bitumenageing at various stages of the production and service of hot mix asphalt.Recent studies have shown that Superpave testing protocol does not fully address the ageing of modified binders. To study the ageing properties of modified binders, three different types of binder modifiers, plastomer, elastomer, and ground... 

Warm mix asphalt has received considerable attention over the past decade particularly due to its potential environmental benefit such as lower energy consumption and emission, its ability to be placed at lower ambient temperatures making it a suitable material for areas with short construction season. There are three warm mix asphalt (WMA) techniques are available; organic additive, foaming, and chemical additive. This study examined Sasobit, a micro crystalline wax which is an organic additive. The concentrations tested were 1.5, 2.5 and 3.5 percent of the base binder. A PG 64-22 asphalt binder from an Iranian refinery (Tehran refinery) was used as the base binder. Superpave binder... 

The deleterious effect of moisture on the structural integrity of asphalt mixtures has been recognized as one of the main causes of early deterioration of asphalt pavements. This phenomenon, usually referred to as moisture damage, is defined as the progressive loss of structural integrity of the mixture. Moisture damage is associated with the development of different physical, mechanical and chemical processes occurring within the microstructure of the mixture at different intensities and rates. Although there have been important advancements in identifying and characterizing this phenomenon, there is still a lack of understanding of the damage mechanisms occurring at the... 

With a surge in consumption of modified binders in recent years, different methods have been used to evaluate the properties of modified binders with relative success. None of these methods are able to fulfill all the requirements for evaluation and intrerpretation of the physical, chemical and rheologocal properties of modified binders. Since rheological master curves can present a mechanical interpretation of the binders in a wide range of times and temperatures, in conjunction with other evaluation metheods, they are considered a promising means of evaluating the suitability of modified bindrers. The available master curve models do not possess the sufficient diversity for this purpose.... 

Pavement preventive maintenance methods such as slurry seals are cost-effective treatments that enhance pavement longevity. Incorporation of recycled materials such as reclaimed asphalt pavement (RAP) into asphalt pavements helps further reduce costs and energy consumption. Because the use of emulsions and pavement preventive methods is uncommon in Iran, there is little experience with the technology in this area. The present study designed and developed slurry seal and emulsion test devices at Sharif University lab to study the feasibility of incorporation of RAP into slurry seal mixtures while respecting the limits specified by the ISSA and ASTM. Two slurry seal mixtures in which cement...