Small amplitude ion acoustic solitons in a weakly magnetized plasma with anisotropic ion pressure and kappa distributed electrons

The Zakharov–Kuznetzov (ZK) equation is derived for nonlinear electrostatic waves in a weakly magnetized plasma in the presence of anisotropic ion pressure and superthermal electrons. The anisotropic ion pressure is defined using Chew–Goldberger–Low (CGL) while a generalized Lorentzian (kappa) distribution is assumed for the non-thermal electrons. The standard reductive perturbation method (RPM) is employed to derive the two dimensional ZK equation for the dynamics of obliquely propagating low frequency ion acoustic wave. The influence of spectral index (kappa) of non-thermal electron on the soliton is discussed in the presence of anisotropic ion pressure in plasmas. It is found that ion pressure anisotropy and superthermality of electrons affect both the width and amplitude of the solitary waves. On the other hand the magnetic field is found to alter the dispersive property of the plasma only, and hence the width of the solitons is affected while the amplitude of the solitary waves is independent of external magnetic field. The numerical results are also presented for illustrations.     

The organic aerosols of Titan

A dark reddish organic solid, called tholin, is synthesized from simulated Titanian atmospheres by irradiation with high energy electrons in a plasma discharge. The visible reflection spectrum of this tholin is found to be similar to that of high altitude aerosols responsible for the albedo and reddish color of Titan. The real (n) and imaginary (k) parts of the complex refractive index of thin films of Titan tholin prepared by continuous D.C. discharge through a 0.9 N₂/0.1 CH₄ gas mixture at 0.2 mb is determined from x-ray to microwave frequencies. Values of n (1.65) and k (0.004 to 0.08) in the visible are consistent with deductions made by ground-based and spaceborne observations of Titan. Many infrared absorption features are present in k(λ), including the 4.6 μm nitrile band. Molecular analysis of the volatile component of this tholin was performed by sequential and non-sequential pyrolytic gas chromatography/mass spectrometry. More than one hundred organic compounds are released; tentative identifications include saturated and unsaturated aliphatic hydrocarbons, substituted polycyclic aromatics, nitriles, amines, pyrroles, pyrazines, pyridines, pyrimidines, and the purine, adenine. In addition, acid hydrolysis produces a racemic mixture of biological and non-biological amino acids. Many of these molecules are implicated in the origin of life on Earth, suggesting Titan as a contemporary laboratory environment for prebiological organic chemistry on a planetary scale.     

Ultra-reliable real-time control systems-future trends

Today's aircraft use ultra-reliable real-time controls for demanding functions such as Fly-By-Wire (FBW) flight control. Future aircraft, spacecraft and other vehicles will require greater use of these types of controls for functions that currently are allowed to fail, fail to degraded operation, or require human intervention in response to failure. Fully automated and autonomous functions will require ultra-reliable control. But ultra-reliable systems are very expensive to design and require large amounts of on-board equipment. This paper will discuss how the use of low-cost sensors with digital outputs, digitally commanded fault-tolerant actuation devices and interconnecting networks of low-cost data buses offer the promise of more affordable ultra-reliable systems. Specific technologies and concepts to be discussed include low-cost automotive and industrial data buses, “smart” actuation devices with integral fault masking capabilities, management of redundant sensors, and the fault detection and diagnosis of the data network. The advantages of integrating the control and distribution of electrical power with the control system will be illustrated. The design, installation, and upgrade flexibility benefits provided by an all-digital and shared network approach will be presented. The economic benefits of systems that can operate following failure and without immediate repair will be reviewed. The inherent ability of these redundant systems to provide effective built-in test and self-diagnostics capabilities will be described. The challenges associated with developing ultra-reliable software for these systems and the difficulties associated with exhaustive verification testing will be presented as will additional development hurdles that must be overcome     

Empirical model of the high-latitude boundary of the Earth’s outer radiation belt at altitudes of up to 1000 km

An empirical model of the high-latitude boundary of the outer Earth’s radiation belt (ERB) has been presented, which is based on the measurement data of electron fluxes on the polar low-orbit CORONAS-Photon, Meteor-M1, and Meteor-M2 satellites. The boundary was determined by a sharp decrease to the background level of the flux of trapped electrons with energies of 100 or 200 keV in the polar part of the profile of the outer radiation belt. A numerical algorithm has been implemented to determine the time moment, when the fastest flux changes are recorded. The primary search was carried out, first, on 30 s averaged data, then repeated on data with a higher resolution. A functional dependence was obtained in order to approximate the obtained set of intersections of the boundary by elliptical curve. The empirical model constructed using the CORONAS-Photon measurement data in the epoch of anomalously low geomagnetic activity reflects the longitude structure of the high-latitude boundary of the outer radiation belt associated with the internal Earth’s magnetic field (MF), as well as its dependence on the universal time. Based on the data of intersections of the high-latitude boundary of the outer ERB (OERB) in the epoch of 2014–2016, the latitudinal shift of the boundary to the equator dependent on geomagnetic activity has been determined, as well as the nightside shift of the boundary due to the diurnal rotation of the Earth.