Profiling of flow passage in axial radial-flow compressor impellers

A procedure of calculating an axial radial-flow centrifugal stage is considered. Using the gas-dynamically expedient load ratio distribution in profile, the process of impeller flow passage profiling is described. Also given are some techniques for decreasing or eliminating a wake zone as well as a graph of loss dependence on the divergence factor and velocity deceleration on the rarefaction side of the blade channel at the impeller outlet.     

The Planetary Laboratory for Image Analysis (PLIA)

The observation, characterization, and understanding of planetary atmospheres are key components of Solar System exploration. Their study requires, among other observations, the use of image data acquired from spacecrafts. The basic tasks that are generally used to work with planetary image data are: image navigation, projection, image processing, limb-darkening correction, composition of multiwavelength images and mosaicing. We illustrate the mathematical techniques required for the study of planetary images obtained from spacecrafts using as an example our own software package (PLIA). We present examples of analysis of Galileo SSI, Cassini ISS and Venus Express VIRTIS observations covering a large range of image peculiarities. The paper is organized as a guide for anyone willing to replicate one or several of the capabilities incorporated in the PLIA software. An open source version of PLIA for astronomical image processing is available.     

Estimation of Galactic Cosmic Ray exposure inside and outside the Earth’s magnetosphere during the recent solar minimum between solar cycles 23 and 24

The evidently low solar activity observed between solar cycles 23 and 24 during the years 2008–2010 led to a substantial increase in the Galactic Cosmic Ray (GCR) intensity in comparison with preceding solar minima. As the GCRs consist of highly-ionizing charged particles having the potential to cause biological damage, they are a subject of concern for manned missions to space. With the enhanced particle fluxes observed between 2008 and 2010, it is reasonable to assume that the radiation exposure from GCR must have also increased to unusually high levels. In this paper, the GCR exposure outside and inside the Earth’s magnetosphere is numerically calculated for time periods starting from 1970 to the end of 2011 in order to investigate the increase in dose levels during the years 2008–2010 in comparison with the last three solar minima. The dose rates were calculated in a water sphere, used as a surrogate for the human body, either unshielded or surrounded by aluminium shielding of 0.3, 10 or 40 g/cm².     

Loss from Approximations to Square-Law Detectors in Quadrature Systems with Postdetection Integration

The trend toward digital processing of radar and sonar signals has ledto the use of ?baseband? or bipolar video signals. The processingof both the in-phase (I) and quadrature (Q) channels generally allows an exact representation of the signals, and no loss of sensitivity need occur. However, for reasons of economy or weight only one channel is often implemented. This correspondence shows that the sensitivity loss for this case often deviates considerably from the 3-dB rule of thumb.     

Pulse Doppler Ambiguity Resolution

A mathematical algorithm using the method of invariant imbedding is developed which generates a best ￡2 estimate of range and range rate from pulse Doppler data.     

Some aspects of psychophysiological support of crewmember's performance reliability in space flight

Crewmembers play an important role in ensuring the efficiency of "crew-spacecraft" system. However, despite of the fact that crewmembers are well trained and highly motivated persons, extreme flight factors may influence negatively on their reliability, and lead to human error occurrence. Therefore, working out methods of human error prevention is very significant to increase crewmember's performance reliability. Human error can occur in the operation of systems for a number of reasons. Within the framework of the present investigation, with use the data collected during "Mir" station missions, the significant (p<0.05) positive correlation of crewmembers errors (CE) frequency with their psychophysiological state (PPS), and work and rest schedule (WRS) intensity has been revealed. Differently, the higher WRS intensity, the crewmember's PPS is worse, and CE frequency is higher. This finding has been based on substantiations of the approach to human reliability management. Its essence will consist of the following: reducing WRS intensity, we thus can improve a crewmember's PPS and, accordingly, reduce CE frequency. This approach is discussed in the paper.     

Facing harsh realities--in space, air, and war

Current legislative activity in Washington includes plans for hearings and proposed changes to NASA after the publication of the Columbia Accident Investigation Board report in August, 2003. Also reviewed are legislative interest in airline safety and armed forces expansion.     

The space-developed dynamic vertical cutoff rigidity model and its applicability to aircraft radiation dose.

We have developed a dynamic geomagnetic vertical cutoff rigidity model that predicts the energetic charged particle transmission through the magnetosphere. Initially developed for space applications, we demonstrate the applicability of this library of cutoff rigidity models for computing aircraft radiation dose. The world grids of vertical cutoff rigidities were obtained by particle trajectory tracing in a magnetospheric model. This reference set of world grids of vertical cutoff rigidities calculated for satellite altitudes covers all magnetic activity levels from super quiet to extremely disturbed (i.e., Kp indices ranging from 0 to 9+) for every three hours in universal time. We utilize the McIlwain "L" parameter as the basis of the interpolation technique to reduce these initial satellite altitude vertical cutoff rigidities to cutoff rigidity values at aircraft altitudes.     

Terahertz circular dichroism spectroscopy: a potential approach to the in situ detection of life's metabolic and genetic machinery

We propose a terahertz (far-infrared) circular dichroism-based life-detection technology that may provide a universal and unequivocal spectroscopic signature of living systems regardless of their genesis. We argue that, irrespective of the specifics of their chemistry, all life forms will employ well-structured, chiral, stereochemically pure macromolecules (>500 atoms) as the catalysts with which they perform their metabolic and replicative functions. We also argue that nearly all such macromolecules will absorb strongly at terahertz frequencies and exhibit significant circular dichroism, and that this circular dichroism unambiguously distinguishes biological from abiological materials. Lastly, we describe several approaches to the fabrication of a terahertz circular dichroism spectrometer and provide preliminary experimental indications of their feasibility. Because terahertz circular dichroism signals arise from the molecular machinery necessary to carry out life's metabolic and genetic processes, this life-detection method differs fundamentally from more well-established approaches based on the detection of isotopic fractionation, "signature" carbon compounds, disequilibria, or other by-products of metabolism. Moreover, terahertz circular dichroism spectroscopy detects this machinery in a manner that makes few, if any, assumptions as to its chemical nature or the processes that it performs.