An ion analyzer for the lunar surface with E-parallel–B

We present a novel instrument concept to measure the energy and mass spectra of ions incident on the lunar surface, based on the E-parallel–B or Thomson-parabola device used extensively as a diagnostic in the plasma fusion community. The Apollo-era Suprathermal Ion Detector Experiment (SIDE) was the first instrument package to perform in-situ measurements of ions incident on the lunar surface. The ions can originate from a variety of sources, including the solar wind, the Earth’s magnetotail, and photoionization of the thin lunar atmosphere. The species and energy distribution of ions arriving at the lunar surface depend in a complicated and poorly-understood fashion on the phase of the lunar day, the position of the Moon with respect to the Earth, and on the local plasma environment.     

Application of Gram-Schmidt algorithm to fully adaptive arrays

The Gram-Schmidt orthogonalization (GSO) algorithm has excellent numerical performance and is readily applicable to systolic implementations such as in a field of adaptive cancellation systems. A modified GSO algorithm for a fully adaptive array is proposed and computer simulations show that the proposed algorithm gives superior performance. A systolic implementation of the proposed GSO algorithm for fully adaptive array is presented. A feedback mode GSO algorithm for use with analog weights is also presented and has been shown to have excellent performance in the presence of weight errors     

On kinematics of gas clouds in the broad-line region of active galactic nuclei and quasars

The kinematics of gas clouds in broad-line region of active galactic nuclei and quasars is considered. The motion of the clouds is governed by three forces — gravitational influence from the central supermassive body, radiational pressure from the continuum radiation, and resistance of the intercloud medium. Clouds moves radial but only outward motion gives a velocity field, which is in accordance with the observational data. The profiles of the permited lines are obtained in some simplify assumptions for the emissive capacity of the gas in clouds, and are in good agreement with the observational data. In the framework of the model under consideration there is a possibility to estimate some physical parameters of the nuclei such as mass of the central body and density of the intercloud medium.     

Multi-criteria analysis of aircraft structures fracture

A novel modular multistep algorithm is proposed for multi-criteria analysis of fracture of aircraft structures with complex geometries. In order to evaluate the algorithm, the crack growth analysis is realized by the following three criteria, namely, the stress intensity factor, the strain energy release rate, and the J-integral. The algorithm implementation by the finite element method is considered and prospects of alternative implementation based on the meshfree methods are assigned.     

Solar sail trajectories with piecewise-constant steering laws

Solar sails have much attracted the interest of the scientific community as an advanced low-thrust propulsion means capable of promoting the reduction of mission costs and the feasibility of missions that are not practically accessible via conventional propulsion because of their large ΔV requirements. To reduce the overall flight time, a given mission is usually analyzed in the framework of a minimum time control problem, with the employment of a continuous steering law. The aim of this paper is to investigate the performance achievable with a piecewise-constant steering law whose aim is to substantially reduce the complex task of reorienting the sail over the whole mission. Unlike previous studies based on direct approaches, here we use an indirect method to optimally select the sail angle within a set of prescribed values. The corresponding steering law translates the results available for continuous controls to the discrete case, and is able of producing trajectories that are competitive in performance with the optimum variable direction program.     

Full characterization of a compact 90Sr/90Y beta source for TID radiation testing

A new methodology for Total Ionizing Dose (TID) tests is proposed. It is based on the employment of an on-chip ⁹⁰Sr/⁹⁰Y beta source as alternative to standard methods such as ⁶⁰Co gamma rays and electrons from LINAC. The use of a compact beta source for TID tests has several advantages. In particular, the irradiation of devices with more than one radiation source results in a better representation of the complex space radiation environment composed of several types, energies and dose-rates. In addition, the use of an easy handling beta source allows the irradiation of electronic devices without any damage to other auxiliary circuit. In this work, ⁹⁰Sr/⁹⁰Y beta source dosimetry and related radiation field characteristics are discussed in depth.In order to validate the proposed source for TID tests, a rather complex device such as the “SPC56EL70L5” microcontroller from ST-Microelectronics was exposed to ⁹⁰Sr/⁹⁰Y beta rays. The results of this test were compared to that of a previous test of another sample from the same lot with a standard gamma ⁶⁰Co source. The electronic performances following the two irradiations have been found to be in excellent agreement, by demonstrating therefore the validity of the proposed beta source for TID tests.     

Induction of high grade astrocytoma (HGA) by protons: molecular mechanisms and RBE considerations.

Protons of a specific energy, 55 MeV, have been found to induce primary high grade astrocytomas (HGA) in the Rhesus monkey (Macaca mulatta). Brain tumors of this type were not induced by protons of other energies (32-2,300 MeV). Induction of HGA has been identified in human patients who have had radiation therapy to the head. We believe that the induction of HGA in the monkey is a consequence of dose distribution, not some unique "toxic" property of protons. Comparison of the human experience with the monkey data indicates the RBE for induction of brain tumors to be about one. It is unlikely that protons cause an unusual change in oncogenic expression, as compared to conventional electromagnetic radiation.