Space debris and micrometeoroid impact on spacecraft elements: Experimental simulation
We study experimentally how optical, electrical, and physical properties of spacecraft surface elements (optical glasses, "metal-insulator-metal" structures, and solar arrays) change upon bombardment by high-speed particles of submicron and micron size. For particle acceleration, we use an electrodynamic accelerator. В© Pleiades Publishing, Ltd., 2013.
It is concluded that the secondary Al3Sc particles play a predominant role on the high-speed impact process. The secondary Al3Sc particles have two effects of stabilizing the matrix structure and acting as source of dislocation. Because the capability of Al–Sc alloy to resist high-speed projectile impact is related to the microstructure, the development of Al–Sc alloy with a combination of fine-grain strengthening and precipitation strengthening is investigated. The results show that Sc additions greater than the eutectic composition (0.55 wt%) were found to produce a remarkable refinement in the grain size. Discontinuous precipitations, which are undesired, are prone to occur in the hypereutectic Al–Sc alloys. For the hypereutectic Al–Sc alloys, control of the aging temperature within a certain range can suppress the presence of discontinuous precipitation, thus the Al–Sc alloy can be strengthened by both the fine-grain strengthening and by continuous precipitation strengthening, which helps to improve the capability to resist high-speed impact.
In the paper the problem of space debris. Describes the causes of debris in near-Earth space. Describes the distribution of debris in near-Earth space. Shown that the accumulation of debris consists of two rings. Analyzes the statistics of debris. We analyze the spatial distribution of debris. Conjectured form rings debris in near-Earth space.
The article contains a description of the methods and software tools for the creation of information-analytical system of monitoring of hazardous space objects. The article presents the structure of the system and a description of the functional components to enable rapid assessment of the NEO hazard and forecast the effects of dangerous collision of celestial bodies with the Earth. There are also the results of the system in terms of modeling the motion of cosmic objects.
Generalized error-locating codes are discussed. An algorithm for calculation of the upper bound of the probability of erroneous decoding for known code parameters and the input error probability is given. Based on this algorithm, an algorithm for selection of the code parameters for a specified design and input and output error probabilities is constructed. The lower bound of the probability of erroneous decoding is given. Examples of the dependence of the probability of erroneous decoding on the input error probability are given and the behavior of the obtained curves is explained.
The dynamics of a two-component Davydov-Scott (DS) soliton with a small mismatch of the initial location or velocity of the high-frequency (HF) component was investigated within the framework of the Zakharov-type system of two coupled equations for the HF and low-frequency (LF) fields. In this system, the HF field is described by the linear Schrödinger equation with the potential generated by the LF component varying in time and space. The LF component in this system is described by the Korteweg-de Vries equation with a term of quadratic influence of the HF field on the LF field. The frequency of the DS soliton`s component oscillation was found analytically using the balance equation. The perturbed DS soliton was shown to be stable. The analytical results were confirmed by numerical simulations.
By using superconducting quantum interference device (SQUID) magnetometry, we investigated anisotropic high-field (H less than or similar to 7T) low-temperature (10 K) magnetization response of inhomogeneous nanoisland FeNi films grown by rf sputtering deposition on Sitall (TiO2) glass substrates. In the grown FeNi films, the FeNi layer nominal thickness varied from 0.6 to 2.5 nm, across the percolation transition at the d(c) similar or equal to 1.8 nm. We discovered that, beyond conventional spin-magnetism of Fe21Ni79 permalloy, the extracted out-of-plane magnetization response of the nanoisland FeNi films is not saturated in the range of investigated magnetic fields and exhibits paramagnetic-like behavior. We found that the anomalous out-of-plane magnetization response exhibits an escalating slope with increase in the nominal film thickness from 0.6 to 1.1 nm, however, it decreases with further increase in the film thickness, and then practically vanishes on approaching the FeNi film percolation threshold. At the same time, the in-plane response demonstrates saturation behavior above 1.5-2T, competing with anomalously large diamagnetic-like response, which becomes pronounced at high magnetic fields. It is possible that the supported-metal interaction leads to the creation of a thin charge-transfer (CT) layer and a Schottky barrier at the FeNi film/Sitall (TiO2) interface. Then, in the system with nanoscale circular domains, the observed anomalous paramagnetic-like magnetization response can be associated with a large orbital moment of the localized electrons. In addition, the inhomogeneous nanoisland FeNi films can possess spontaneous ordering of toroidal moments, which can be either of orbital or spin origin. The system with toroidal inhomogeneity can lead to anomalously strong diamagnetic-like response. The observed magnetization response is determined by the interplay between the paramagnetic-and diamagnetic-like contributions.
This volume presents new results in the study and optimization of information transmission models in telecommunication networks using different approaches, mainly based on theiries of queueing systems and queueing networks .
The paper provides a number of proposed draft operational guidelines for technology measurement and includes a number of tentative technology definitions to be used for statistical purposes, principles for identification and classification of potentially growing technology areas, suggestions on the survey strategies and indicators. These are the key components of an internationally harmonized framework for collecting and interpreting technology data that would need to be further developed through a broader consultation process. A summary of definitions of technology already available in OECD manuals and the stocktaking results are provided in the Annex section.