Automatic Light Control Electro-Optical CCDTV Systems

For electro-optical TV systems, a simplified method of analysis has been developed for an automatic light control (ALC) loop preliminary ary design and performance trade-offs. With iris and shutter control mechanization incorporated, not only does the input light range increase, but the video response overshoot and settling time are reduced as well. This study shows that the appealing notion of heavily damped response is not often true, particularly in the realtime ime airto-ground surveillance of targets with varying backgrounds. In addition, with exponential and geometric feedback functions introduced, the resultant ALC dynamics are independent of the input light level. To verify the assumptions made and to demonstrate the feasibility of a working model, a complete system simulation is performed.     

The use of model-based test requirements throughout the productlife cycle

Test requirements, which are generally collected in multiple disparate formats throughout the life cycle of an electronic product, could be used in various applications that reduce test and development cycle times and increase the confidence in the final test program. Unfortunately, test requirements are seldom captured in a consistent format that may be processed by a computer, thus eliminating the possibility of using such requirements in an engineering application. Additionally, such an approach disallows test requirements captured in one segment of the product life cycle to be reused in subsequent life cycle stages. This paper describes a model-based methodology, specifically the Test Requirements Model (TeRM), which can be shown to facilitate the transfer of test-related product information between various stages of the life cycle. This transportability, in conjunction with an exchange format that can be processed by a computer, permits test requirement information to support value-added applications in the engineering process throughout the life cycle of a product     

Deconvolution of Energetic Neutral Atom Images of the Earth's Magnetosphere

A method for deconvolving equatorial pitch angle distributions of energetic neutral atoms from images from the ENA instruments on the IMAGE satellite is described and illustrated using simulated data obtained from calculated models of ring current flux. The unknown flux is expanded in terms of cubic B-splines and Legendre polynomials. The expansion coefficients are obtained from the solution of a linear set of equations that select the smoothest solution that fits the data. In this way, all the information that is contained in the data is extracted but no more.     

An approximated method of calculating the cellular insert influence in the carrying capacity of the direct-flow labyrinth seal

A method for calculating the flowrate of the gas flowing through the cellular insert cells over the labyrinth seal strip is proposed. The gas density is taken to be average with respect to the decisive section. It is assumed that jets flowing out of cells disrupt the direct flow of the labyrinth seal. A practical implementation of the method is confirmed by the known experimental data.     

A two-phase mixture drift flow in the vertical cylindrical channel

The mathematical models of the solid-liquid flow regimes in the vertical cylindrical channel are described. A two-speed flow based on the solid-liquid phase interaction is considered. The problem was numerically solved and the calculation results were compared with experimental data.     

Small perturbation propagation in the viscoelastic fluid enclosed in a multilayer viscoelastic tube

A pulsating flow of the incompressible viscoelastic fluid enclosed in the multilayer viscoelastic tube of a variable circular section is investigated. The problem stated leads to the singular Sturm-Liouville boundary value problem which in its turn is reduced to the equivalent integral equation of the Volterra type that is solved by the successive approximation method. The influence of fluid relaxation and retardation time on the wave system characteristics is revealed.     

Some Aspects of Swerling Models for Fluctuating Radar Cross Section

The structure of Swerling's 1957 model for fluctuating radar cross section and signal amplitude is examined prinwrily in terms of mixture representations. The authors also show the relationship of Nakagami's m distrubution to Swerling's amplitude distribution, and Nakagami's q distribution (Hoyt vector density) is reduced to the Swerling distribution. Nonuniform phase distributions associated with Swerling's functions are also derived. Results are given when Swerling's amplitude density is used as a prior distribution with Bennett's (Rice's) distribution for the amplitude of a sine wave plus narrowband Gaussian noise.     

Remarks on ?Comments on 'Signal Resolution via Digital Inverse Filtering'?

Published comments on a recent paper criticized the use of inverse filtering as applied to resolution of overlapping radar signal returns. It is shown that an inadequate model of the inverse filter was assumed by the critic, which lead him to predict excessive time sidelobes at the filter output. It is demonstrated, by computer simulation, that the time sidelobes at the output of the true inverse filter are down 30 dB or more.     

Interstellar Mapping and Acceleration Probe (IMAP): A New NASA Mission

The Interstellar Mapping and Acceleration Probe (IMAP) is a revolutionary mission that simultaneously investigates two of the most important overarching issues in Heliophysics today: the acceleration of energetic particles and interaction of the solar wind with the local interstellar medium. While seemingly disparate, these are intimately coupled because particles accelerated in the inner heliosphere play critical roles in the outer heliospheric interaction. Selected by NASA in 2018, IMAP is planned to launch in 2024. The IMAP spacecraft is a simple sun-pointed spinner in orbit about the Sun-Earth L1 point. IMAP’s ten instruments provide a complete and synergistic set of observations to simultaneously dissect the particle injection and acceleration processes at 1 AU while remotely probing the global heliospheric interaction and its response to particle populations generated by these processes. In situ at 1 AU, IMAP provides detailed observations of solar wind electrons and ions; suprathermal, pickup, and energetic ions; and the interplanetary magnetic field. For the outer heliosphere interaction, IMAP provides advanced global observations of the remote plasma and energetic ions over a broad energy range via energetic neutral atom imaging, and precise observations of interstellar neutral atoms penetrating the heliosphere. Complementary observations of interstellar dust and the ultraviolet glow of interstellar neutrals further deepen the physical understanding from IMAP. IMAP also continuously broadcasts vital real-time space weather observations. Finally, IMAP engages the broader Heliophysics community through a variety of innovative opportunities. This paper summarizes the IMAP mission at the start of Phase A development.