Sharif Digital Repository

The X80 high-strength low-alloy microalloyed steel was procured as a hot rolled plate with accelerated cooling. The four-wire tandem submerged arc welding process, with different heat input, was used to generate a welded microstructure. The effects of real and Gleeble simulated double pass thermal cycles on the properties of the heated and reheated coarse grained heat affected zones (CGHAZ) in X80 microalloyed pipeline steel has been investigated. The thermal simulated process for heated region involved heating the X80 steel specimens to the peak temperature of 1400 °C, with different cooling rates. The influence of the second peak temperature during real and simulated welding hass been... 

Polymerase Chain Reaction (PCR) is a process in which a special piece of a gene is amplified millions of times over a short period. This method has been of paramount importance in different fields of research and has been applied for different applications. PCR requires thermal cycling, or repeated temperature changes between two or three discrete temperatures to amplify specific nucleic acid target sequences. To achieve such thermal cycling, conventional bench-top thermal cyclers generally use a metal heating block powered by Peltier elements or benefit from forced convection heat transfer. Due to the fact that these methods are time consuming, it seems that design and fabrication of a fast... 

Polymerase chain reaction method is a conventional method for obtaining multiple copies of a specified segment in the DNA molecule and to amplify the DNA molecule itself. Therefore, this method has been of paramount importance in different fields of research and has been applied for different applications. PCR requires thermal cycling, or repeated temperature changes between two or three discrete temperatures to amplify specific nucleic acid target sequences. To achieve such thermal cycling, conventional bench-top thermal cyclers generally use a metal heating block powered by Peltier elements or benefit from forced convection heat transfer. Although efforts have been made in order to reduce... 

Concrete-filled GFRP and PE tubes are composite systems using the polymeric tubes as confinement for the marine structures to extend their service life. However, elevated temperatures and thermal cycles in marine environments can affect the behavior of such composite systems. In this investigation, the effect of elevated temperatures and thermal cycles on the performance of concrete-filled pultruded GFRP tubes (CFPGT) and concrete-filled polyethylene tubes (CFPT) is assessed, respectively. For this, different parameters such as concrete core strength (30 and 60 MPa), exposure temperature (25, 100, 200, 300, and 400°C), time exposure (60 and 120 min.), number of thermal cycles (50, 100, and... 

Ni-Ti shape memory alloys have attracted most of the research in the field of shape memory alloys both because of their complicated and diverse phase transformation characteristics and their optimum properties for various applications which span such a properties as shape memory effect, pseudoelasticity, excellent mechanical properties and biocompatibility. The key properties of these alloys is generated through a thermoelastic martensitic transformation the occurrence of which is extremely sensitive to the metallurgical conditions of the alloy e.g. composition and microstructure. This has led to the development of various procedures implemented in either fabrication, processing or heat... 

According to the recent researches it has been found that wind can reduce the efficiency of Air Cooled Condensers (ACC) which use for cooling purposes in power plants. Wind affects the natural suction of the cooling air and makes local low pressure area in fan’s inlet results to disrupt its normal performance. Using aerodynamic obstacles inside and around the condensers can compensate this lack of performance when there is strong wind. In this thesis with the aid of computational fluid dynamics, condenser’s behavior with various weather situations is studied. Simulation in no wind situation and different wind speeds is considered and accomplished with Gambit Fluent software. This simulation...