Electron-Ion Temperature Equilibration in Collisionless Shocks: The Supernova Remnant-Solar Wind Connection

Collisionless shocks are loosely defined as shocks where the transition between pre-and post-shock states happens on a length scale much shorter than the collisional mean free path. In the absence of collision to enforce thermal equilibrium post-shock, electrons and ions need not have the same temperatures. While the acceleration of electrons for injection into shock acceleration processes to produce cosmic rays has received considerable attention, the related problem of the shock heating of quasi-thermal electrons has been relatively neglected. In this paper we review the state of our knowledge of electron heating in astrophysical shocks, mainly associated with supernova remnants (SNRs), shocks in the solar wind associated with the terrestrial and Saturnian bowshocks, and galaxy cluster shocks. The solar wind and SNR samples indicate that the ratio of electron temperature, (T _e ) to ion temperature (T _p ) declining with increasing shock speed or Alfvén Mach number. We discuss the extent to which such behavior can be understood on the basis of waves generated by cosmic rays in a shock precursor, which then subsequently damp by heating electrons, and speculate that a similar explanation may work for both solar wind and SNR shocks.     

Iran's space programme: Riding high for peace and pride

Iran's efforts to develop space technology for civil and peaceful purposes began many years ago. Almost all its success in this connection is the result of indigenous potential in terms of human resources, available expertise and experience along with international cooperation and exchange of knowledge. There are considerable civilian entities involved in space-related development and production in Iran. This article describes the history and current status and capabilities of Iran's space programme and its aim to use space for peace and prosperity and to attain the position that it deserves in the global arena. Stepping into space using an indigenously developed system has provided Iran with a notable and unprecedented national pride. Only international cooperation, as already exists in the framework of COPUOS activities on the peaceful uses of outer space, can improve 21st century understanding of the space policy and visions of Iran for the world community. Iran's space programme is really no different from that of any other nation. It is committed to developing its assets in space both for peaceful purposes and for use as part of various multinational space projects. It should not be ignored that such achievements require a high degree of expertise, ability and comprehensive knowledge about the subject, while the attitudes and visions of leaders in each nation who also influence and contribute to the pace, progress and developmental objectives of any nation's space program should not be disregarded.     

An efficient aerodynamic shape optimization of blended wing body UAV using multi-fidelity models

This paper presents a novel optimization technique for an efficient multi-fidelity model building approach to reduce computational costs for handling aerodynamic shape optimization based on high-fidelity simulation models. The wing aerodynamic shape optimization problem is solved by dividing optimization into three steps—modeling 3D(high-fidelity) and 2D(lowfidelity) models, building global meta-models from prominent instead of all variables, and determining robust optimizing shape associated with tuning local meta-models. The adaptive robust design optimization aims to modify the shape optimization process. The sufficient infilling strategy—known as adaptive uniform infilling strategy—determines search space dimensions based on the last optimization results or initial point. Following this, 3D model simulations are used to tune local meta-models. Finally, the global optimization gradient-based method—Adaptive Filter Sequential Quadratic Programing(AFSQP) is utilized to search the neighborhood for a probable optimum point. The effectiveness of the proposed method is investigated by applying it, along with conventional optimization approach-based meta-models, to a Blended Wing Body(BWB) Unmanned Aerial Vehicle(UAV). The drag coefficient is defined as the objective function, which is subjected to minimum lift coefficient bounds and stability constraints. The simulation results indicate improvement in meta-model accuracy and reduction in computational time of the method introduced in this paper.