Sharif Digital Repository

Although Pulsed Plasma Thruster (PPT) has first been utilized in a space mission in 1964 but after more than four decades, it is still a space rated technology which has performed various propulsion tasks from stationkeeping tasks to three-axis attitude control for a variety of former missions. With respect to the rapid growth in the small satellite community and the growing interest for smaller satellites in recent years, PPT is one of the promising electric propulsion devices for small satellites (e.g. CubeSats) as the following advantages: simplicity, lightweight, robustness, low power consumptions, low production costs and small dimensions. In spite of the fact that the issues relating... 

thermoacuostic heat pump (THP) is One of the most important thermoacuostic applications which is used for heat lost recovery in industrial applications and civil applications.In this project, we have a quick review on thermoacuostic theory and researches in this field. Also a thermoacuostic heat pump in a lab scale will be designed and analyzed.For achieving this goal, first, mathematical equations of thermoacuostic systems are reviewed; a thermoacuostic heat pump is designed on the base of Tijani method and final model is validated by DeltaEC software. In the next step, after investigating about laboratory equipments which is used in testing process, we generate test matrix and study about... 

Real time hybrid simulation is considered as one of the most efficient experimental methods for investigation of the behavior of structures and their components during seismic loading. In pseudo-dynamic approach of hybrid simulation considered in this study, the majority of the structural mass is modelled numerically and inertia forces are calculated in the numerical model.Using this approach, loading can be carried out on a real-time basis, and component scaling requirements will be reduced. As a result, in addition to lower costs, this testing method is sometimes considered to be more realistic compared to shaking table tests. However, several challenges are currently faced in... 

Regaining biomechanical function, comfort and quality of every-day life is a prime consideration when designing prosthetic devices for amputees. The magnetorheological (MR) prosthetic knee, which is the subject of this study, is an example of such a device. The study presents a comprehensive and a combined MR device design and MR fluid design approach, aiming to advance the MR prosthetic knee. First, this study focuses on developing a new configuration on magnetorheological (MR) brake damper as prosthetic knee. The new configuration is a rotary damper using MR fluid with a single rotary disc will act as a brake while MR fluid is activated by magnetic field in different walking gait. The main... 

The aim of the current research is to study the process of making a solidstate nanopore by molding from PDMS polymer and to make a laboratory sample of a solidstate nanopore manufacturing device using this method. Solid-state nanopores are used to control ion transport in microfluidic channels,lab-on-a-chip detection to study nucleic acids and proteins, desalination, nanofluidic transistors,single-cell sensing tools, and particle classification. In general, the smaller the nanopore, the shorter the length and the higher the mechanical stability, the better the performance. In this research, chips have been made on which there is a blade with a sharpness of 10 nanometers and a height of 10... 

In this research, an experimental prototype of an underwater actuator is designed, fabricated and tested using Shape Memory Alloy (SMA) wires. The mechanism is simply designed and among its advantages are sharp response and electrically activation. Also its independence from hydraulic, pneumatic and or classical gear based control mechanisms is noteworthy. To fabricate the mechanism, a NiTi wire is selected and heat treated as shape setting process. The mechanical and electrical studies are done as well according to tension and recovery forces tests due to mechanical and thermoelectrical loadings. Further, the SMA wires are layed as a 1×7 wire rope together and similar heat treatments...