نشریه فناوری در مهندسی هوافضا
پیاپی 3 (زمستان 1396)

The immune system is a complex network of biological structures and processes that by reducing its function or slightly modifying any of its aspects can increase the risk of disease. Research suggests that gravity changes cause alterations in the immune system. This could also lead to conditions where astronauts suffer from skin irritation, abnormal allergies orreactivation of latent viruses. Furthermore, several bacterial strains can proliferate more readily in space which may be related to human reduced immunity. Also, it is observed that some immune cells are impaired and there are changes in the amount of protein produced by these cells. Hence, the weakening of the immune system due to space flight is an area of research that should be fully evaluated in order to maintain the homeostasis of body under such conditions. This article briefly describes the microgravity effects on the immune system, and the results could have ground application in addition to implications for the flight crew.

A communications satellite is an artificial satellite that relays and amplifies radio telecommunications signals via a transponder; it creates a communication channel between a source transmitter and a receiver on different locations on Earth. Communications satellites are used for television, telephone, radio, internet, and military applications. Communications satellites are usually composed of the following subsystems:1) Communication payload, normally composed of transponders, antennas, and switching systems; 2)Engines used to bring the satellite to its desired orbit; 3)Station keeping tracking and stabilization subsystem used to keep the satellite in the right orbit;4)Power subsystem, used to power the satellite systems, normally composed of solar cells; and 5)Command and control subsystem. There has been longstanding debate regarding the comparative reliability of solid-state power amplifiers (SSPAs) versus traveling wave tube amplifiers (TWTAs) for the satellite downlink. Many trade studies on comparing SSPAs and TWTAs rely on transistor device life test data on the ground for SSPAs due to the lack of statistically significant data on orbit. It is expected that the current on-orbit statistics in the industry shed relevant light on the debate.

Flutter is an unintended phenomenon due to interactions between aerodynamic forces, elasticity and inertia, which leads to unstable structural fluctuations, often leading to structural failure. Most high speed and/or flexible aircraft are highly sensitive to flutter. In this research, extended methods in the last few decades in flutter flight testing are reviewed. Similarly, structural excitation systems, measurement systems, digital processing of data and methods for extracting frequency and damping parameters are considered. Also, the practical experience in this context is mentioned and the current state of this research area is explored.

Supplying the energy for the astronaut’s activity is an important factor in space explorations. Space food also reduces the harmful effects of space besides supplying energy. Space food entails a variety of food products, specially created for consumption by astronauts in the outer space. The food has specific properties in order to provide balanced nutrition for individuals working in space, while being easy and safe to store, prepare and consume in theweightless environments of manned spacecraft. Also, foods taken into space must be light-weight, compact, tasty and nutritious. They must also be kept for long periods without refrigeration. A variety of menus of foods provide each astronaut with 2500 or more calories per day. In this paper, the food ingredients required for astronauts and and essential nutritional factors is studied. Additionally, the trend of space food system improvement is mentioned briefly.Furthermore, the effect of situation which exists in the space, like the impact on microgravity, on astronaut’s body, and protection of the astronaut body are mentioned.

Nowadays, with regard to the new methods of simulation, the designof airfoils have greatly changed and this allows the evaluation of the effect of various factors on the efficacy of airfoils. Thus, choosing the type of wing would be so important; in another term, designing a proper wing is what an airplane designer is mainly concerned with. In this project, the effect of airfoil wave surface on the changes of coefficients of lift and drag are studied. Graphs of lift and drag coefficients, Cantor Distribution Pressure and Cantor Distribution speed are alsoinspected in different attack angles. The achieved results indicate that wavy airfoils atspecific attack angle and also near the angle of extinction have a better performance than airfoils without wavy surface. The results of airfoil performance in different attack angles shown throughgraphs indicate the proper performance of wavy wing.

In this paper, a new generation of supersonic business jets (SSBJs) are studied. First, some of the most important challenges in the course of development of supersonic business jet technologies and strategies to overcome these challenges are studied. Time saving is the most important advantage of using these jets (SSBJs) in civil transportation.The focus of this study is on the introduction of companies and organizations active in development of SSBJs. Also, the timeline of these companies and organizations entering this the production for civil transportation is provided.