Sharif Digital Repository

The use of multi-layer random polypropylene (PPR) pipes of pipe-grade is expanding in the construction industry. The middle layer of these pipes is traditionally reinforced with glass fibers to meet the temperature and internal pressure conditions of the pipe. In recent years, with the aim of improving the lifespan and efficiency of these pipes and considering the perspective of using natural materials instead of synthetic materials, the use of basalt fibers has also been on the agenda of the pioneers of this industry. Basalt fibers are natural mineral fibers obtained from volcanic rocks. Compared to glass fibers, basalt fibers have approximately 5% higher density; however, their tensile,... 

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... 

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... 

In this project ionic liquid and there mixtures were coated on Pt/ Al2O3 , the prepared catalyst were characterization by SEM, BET and XRD techniques.In the first stage the effect of the coated ionic liquid on the Pt/Al2O3 were investigated, on the rate of C=C hydrogenation. in the second stage effect of the thickness of ionic liquids on the rate of the cyclohexene hydrogenation were studied. Result revelad that by increasing the ionic liquid polarity, the reaction rate increased. Also the reaction rate decreased by increasing the thickness of ionic liquid  

In the first part of this research, we have developed a simple and effective ratiometric fluorescence sensor for selective detection of dopamine (DA) in alkaline media by simply mixing thioglycolic acid (TGA) functionalized orange fluorescent cadmium telluride (CdTe) quantum dots (QDs) with amino-functionalized blue fluorescent carbon nanodots (CDs). Under a single excitation wavelength of 365 nm, the sensor exhibits dual-emissions centered at 445 and 603 nm. The fluorescence of CdTe QDs is selectively quenched by DA, whereas the fluorescence of CDs is insensitive to the analyte. In the presence of different amounts of DA, the variations in the dual emission intensity ratios exhibit a... 

This paper studies a multi-product, multi-period, multi-allocation hub location problem based on real case in domestic automotive industry. As 3PL companies spread, using dynamic hubs in a contractual manner becomes passible; So in this paper the hub set is the combination of both static and dynamic hubs. The nodes are suppliers, sites and dealers of a supply chain that have certain demand of each product in each period. In this problem backlogging is allowable and causes penalty. Different transportation modes like road and railroad are usable just in hub network. Direct transmission is possible and candidate hubs are capacitated with multi suggested capacities. A mixed integer programming... 

Todays, given the existence of a strong competitive environment in the industry, supply chains should be quick and reactive, in addition to keeping their costs down. Transit warehouses and warehousing issues are one of the most efficient techniques that reduce inventory costs, while increasing the flow of goods and shorter transport cycles. Regardless of how a warehouse system is designed, the allocation and sequencing of input and output trucks to platforms is considered necessary. The inappropriate sequence of input and output trucks on the platforms increases the completion time of the operation. Also, the uncertainty and unpredictable circumstances of the real world make planning and... 

Supply chain management is very important in pharmaceutical industry, due to its impact on people’s health. In this thesis we considered a three-layer multi-product multi-period pharmaceutical supply chain and we proposed a mixed-integer linear programming model to solve location, allocation, inventory and routing problems in this supply chain. This model aims to minimize the total costs in the supply chain. In this problem we also considered the deterioration of medicines. To bring the model closer to real world problems we considered demand as an uncertain parameter and handle the uncertainty using robust programming. We solve the model with large scale examples using genetic and Particle... 

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... 

With ever-increasing usage of cloud pattern, resources allocation in cloud environments is drawing an emerging importance. Due to nature of cloud environment, and in particular the presence of independent selfish agents, game theory is used as a modeling and problem solving tool in this field. Most of current cloud providers, use static pricing and rather long contracts in their provisioning and allocation process, which is in contrast with cloud’s elasticity principles. Various studies in this area, use game theory, and provide dynamic allocation and pricing mechanisms in form of auctions. An important shortcoming of these studies is oversight of distribution in cloud environment. This... 

Due to their enormous CO/〖NO〗_x removal capabilitiy, catalytic converters are deemed as indispensable parts of modern vehicles. These converters are comprised of a bundle of parallel tubes which their internal walls are wash-coated with a catalyst such as platinum or rhodium. The typical geometry for the tubes’ cross-section is honeycomb. In this project, the effect of tube cross-section geometry on CO/〖NO〗_x removal performance of catalytic converters is studied. In this respect, a three-dimensional model consisted of incompressible flow, advection-diffusion, and surface reaction was developed. Candidate geometries were triangle, square, honeycomb, and circle. The results show that as the... 

There are experimental observations that show material response in micro-scale is dependent on some other parameters rather than Lame parameters. Strain gradient elasticity has been recently developed to take into account this characteristic of materials response. In strain gradient elasticity, characteristic length parameters enter the constitutive equations through the elastic strain energy density function. The elastic strain energy density function is assumed to be a function of the gradient of strain tensor in addition to the strain tensor. In this way, new material constant (characteristic length parameters) are introduced and entered into the constitutive equations. In recent years,... 

Cooperative communications have been introduced to combat degrading effects of fading in wireless networks and attracted much attention recently. This technique provides distributed spatial diversity that enables energy-efficient transmission of information from source nodes to destination nodes via intermediate relay nodes. Most existing protocols, detection techniques and optimization methods in cooperative networks assume that perfect channel state information is available. While in practical situations, the estimates of the channels may only be known and for acquiring such knowledge, a fraction of power and bandwidth have to be spent for channel estimation using pilot symbols. In this... 

Today safety is one of the major competition factors in automotive industries . The vehicles of today are more and more dependent on electronic systems , for driving safety and ease on control for the driver . Some systems are more or less standard in vehicles on the market , examples of such systems are ABS , ABC , etc. Despite of the effect of these systems on vehicle dynamics ,because they only control longitudinal dynamics and don't receive any feedback from vehicle lateral behavior , now control systems ,named VDC , have been developed and implemented in advanced vehicles. The operation of such systems is as this that in any time instance they evaluate vehicle dynamical behavior.... 

Methods that has been used for articular defects are faced with many limitations, so new therapies based on tissue engineering were taken into consideration in recent years. However, tissue engineering also encounters challenges regarding optimal scaffold construction and suitable cell source selection. Mature harvested chondrocytes are limited in number and may lose their chondrogenic potential in several cultures, leading to dedifferentiation. In addition, using stem cells also presents unique challenges associated with them, among which hypertrophic differentiation is the most substantial problem. Choosing the appropriate biomaterial similar to the cartilage structure with sufficient... 

Strain rate dependence of plastic yield and failure properties displayed by most metals affects energies, forces and forming limits involved in high speed forming processes. This paper investigates the influence of the strain rate on the forming properties of some industrial sheet metals used in Automotive and Aerospace industries. First, Split Hopkinson Tensile Bar (SHTB) experiments are carried out to determine the influence of the strain rate on the materials’ stress-strain curves. Then, the SHTB results are used to model the constitutive behaviour of the metal sheets using the phenomenological Johnson-Cook (JC) and Voce models. Finally, forming limit diagrams (FLDs) are calculated using...