Sharif Digital Repository

Road transportation has long been an important form of transportation for mankind. Mass production of motorized vehicles and a growing number of people using human and goods transportation have led engineers to monitor road pavement condition and to act on accordingly in the case of degradation. Due to road networks expansion and budget restrictions, road pavement maintenance and rehabilitation projects should be prioritized based on up-to-date data. Automatic collection of data related to the pavement condition such as the number and the length of cracks, could save time and reduce cost and workforce. This research proposes a hybrid method composed of two independent techniques for... 

Despite major environmental and economic benefits of cold recycled asphalt mixtures, many agencies have not yet made widespread use of this technology due to its so-called poor field performance and lack of accurate information on mechanical properties of cold recycled mixtures. Fiber is one the additives that is sometimes used to enhance asphalt mixture properties. Using fibers to improve the performance of cold recycled asphalt mixture has been studied by a few researchers with somehow contradictory results. In this research, the effects of adding four synthetic fibers (Polypropylene, A-glass, Para-Aramid, and Polyester) and two waste fibers (Waste Polyester and Waste Nylon) with different... 

This study aims to investigate the mechanical properties and performance of cold recycled asphalt mixtures (CRM). So far, several methods have been proposed for designing CRMs, which are mostly based on the volumetric and mechanical properties of the mixtures. In the meantime, few researches have considered performance of those mixes. The main approach of current research is to evaluate and enhance performance characteristics of CRMs regarding common distresses including early-raveling, moisture damage, fatigue cracking by an appropriate additive.Raveling and Cantabro tests were employed to evaluate the resistance of CRM against abrasion and semicircular bending test (SCB) and crack tolerate... 

The health of the pavement ensures the safety and convenience of drivers and passengers. In the past few decades, pavement management systems have encountered challenges that often have produced solutions with excessive demand for resources, but low-accuracy results. New approaches must be developed in order to quickly and economically identify pavement failure, especially cracks. In recent years, researchers have focused on identifying pavement failures, but previous methods only worked on images that solely included pavements and cracks. However, when foreign objects such as cars and vegetation were present, these methods were not as effective. To improve upon these methods, semantic... 

Recent advancements have led to the widespread adoption of cold asphalt mixtures, primarily due to their numerous benefits, including reduced fuel consumption and lower emissions of harmful gases such as CO2. These mixtures are utilized for various applications, notably in road repair and maintenance. The duration required for cold asphalt layers to attain the requisite mechanical strength is termed the curing time. Various transportation agencies and authorities employ different methodologies to ascertain this curing period. Some agencies determine it based on the minimum moisture content of the mixture, often cited as 1.5% in several studies. Others prescribe a curing duration ranging from... 

Pavements are essential part of transportation infrastructures that are expensive to build and maintain and could significantly affect the environment. In recent decades, global warming has become a major concern. Therefore, in pavement design in addition to the economic and environmental considerations, conformity with sustainable development have received attention. In the past decades in Iran, because of the low production and high price of cement, and availability of inexpensive bitumen, flexible pavements were the predominant type. However, the increased price of bitumen in the past two decades has changed the balance of the highway construction projects, and bitumen procurement has... 

In recent decades, the use of modifiers has been one of the common methods on major roads to inhibit cracking and permanent deformation in asphalt pavements. Simultaneously, due to the economic and environmental benefits of hot mix asphalt recycling, the consumption of recycled asphalt pavement on all types of roads has been on the rise. However, a significant issue with recycled asphalt mixtures is their susceptibility to various types of cracking, as a result of the increased stiffness and brittleness of the recycled asphalt binders. To address this issue, two main questions need to be answered; a) the potential positive effects of modifiers left in the recycled mixture to be accounted for... 

In this paper we determine “Tax Incidence” of value added tax (VAT). Incidence Tax represents tax burden that is imposed to each tax-payers: consumers or producers. Value added tax was first implemented in Iran in Mehr 1387. Providing a natural experiment condition, it made it possible to measure tax incidence by using difference-in-difference method. Therefore, data of monthly consumer price index of 23 tax-exempt commodities, and 23 taxable commodities, have been used from Farvardin 1384 till Esfand 1393. According to the results, from 1387 to 1390, no tax incidence regarding value added tax was found. It seems, in the first years of implementation, it is the result of its resemblance with... 

Enzymes are an important part of detergents, they reduce the activation energy of the reaction and thus increase the efficiency of the process. Protease enzyme is one of the most common enzymes in detergents. Bacillus strain is the most important strain in the production of this enzyme and among the species of Bacillus, Bacillus subtilis is the most used. Bacillus subtilis is a gram-positive, rod-shaped bacterium. This bacterium is considered a non-pathogenic cell that has the ability to form spores and prevent death and damage in harsh conditions. In this study, CRISPR system was used to modify the genome of Bacillus subtilis ATCC 6633 in order to increase alkaline protease. To increase the... 

Digital Signal Processing (DSP) is used in a wide range of applications such as high-definition TV, digital audio, multimedia, digital cameras, radar, sonar detectors, biomedical imaging, global positioning, digital radio, speech recognition and etc. These applications can be implemented by either DSP processors or FPGA technology. Digital Signal Processors are microprocessors specifically designed to handle Digital Signal Processing tasks. These devices have seen a tremendous growth in the last decade, finding use in everything from cellular telephones to advanced scientific instruments. On the other hand, the rise of FPGA in the signal processing realm could be assigned to hardware to... 

High-quality online services demand reliable and fast packet delivery at the network layer. However, clear evidence documents the existence of compromised routers in the ISP and enterprise networks, threatening network availability and reliability. A compromised router can stealthily drop, modify, inject, or delay packets in the forwarding path to launch Denial-of-Service, surveillance, man-in-the-middle attacks, etc. So researches tried to create intrusion detection methods to identify adversarial routers and switches. To this end, data-plane fault localization (FL) aims to identify faulty links and is an effective means of achieving high network availability. FL protocols use... 

Confining nematic liquid crystal between two curved boundary conditions while the nematic molecules have a degenerate planar anchoring leads to complex and beautiful textures of molecular disparagement(defect) in the bulk and on the surfaces. Such the liquid crystal shells are made with double-emulsion techniques in microfluidic devices have provided applications for micro-scale colloidal linkers.In this work, we have numerically minimized the elastic energy in one-constant approximation in present of Fournier’s degenerate surface potential with finite element method. The nematic shell is confined between two spherical surfaces that we have studied the final energies and their related... 

In the areas where the soil beneath the foundation is made of loose to semi-consolidated sand or noncohesive silts, Buildings and bridges are usually built on the pile foundations. One important issue that must be considered in the design of piles in saturated sandy soils, is liquefaction potential of saturated sandy soil under earthquake loads. During the earthquake, saturated sandy soil faces the sudden loss of shear strength in other word it liquifies . Liquefied Soil acts like a viscous fluid. This behaviour considerably increases the soil deformation and consequently the widespread disruption of soil layers, causes large deformation and applies great amount of forces on the piles... 

Hydrogen fuel cell is one important choice to supply energy for vehicles in near future. The lack of a safe but inexpensive technology to store hydrogen in a vehicle tank is a serious challenge to commercialize the application of fuel cells. Past experiments have shown that carbon nanostructures, especially single walled carbon nanotubes, have considerable capacity to boost up hydrogen storage. Therefore, many studies have been performed to investigate the possibility of higher hydrogen storage capability using nanostructures for the past decade. Molecular dynamics method which is considered as one of the most important tools in studying nanostructures has shown vast applications in these...