Prediction, evaluation, and specification of flying qualities by means of step target tracking

A new approach to flying qualities specification and evaluation is presented which coordinates current research in the areas of pilot ratings, pilot-aircraft modeling techniques, and simulation and flight test procedures. A time-domain pilot model is described which can model discontinuous and nonlinear pilot behavior in conjunction with completely general time-varying nonlinear aircraft models to simulate discrete maneuvers. This pilot-aircraft model is applied to an existing set of in-flight simulation data, and calculates tracking error and time-on-target statistics for step target tracking that directly relate to the reported pilot comments and ratings. Predicted step target tracking data for eighteen F-5E flight conditions are presented, and the use of the method for control system design is demonstrated using the YF-17

Prediction of pilot reserve attention capacity during air-to-air target tracking

Reserve attention capacity of a pilot was calculated using a pilot model that allocates exclusive model attention according to the ranking of task urgency functions whose variables are tracking error and error rate. The modeled task consisted of tracking a maneuvering target aircraft both vertically and horizontally, and when possible, performing a diverting side task which was simulated by the precise positioning of an electrical stylus and modeled as a task of constant urgency in the attention allocation algorithm. The urgency of the single loop vertical task is simply the magnitude of the vertical tracking error, while the multiloop horizontal task requires a nonlinear urgency measure of error and error rate terms. Comparison of model results with flight simulation data verified the computed model statistics of tracking error of both axes, lateral and longitudinal stick amplitude and rate, and side task episodes. Full data for the simulation tracking statistics as well as the explicit equations and structure of the urgency function multiaxis pilot model are presented

Error rate information in attention allocation pilot models

The Northrop urgency decision pilot model was used in a command tracking task to compare the optimized performance of multiaxis attention allocation pilot models whose urgency functions were (1) based on tracking error alone, and (2) based on both tracking error and error rate. A matrix of system dynamics and command inputs was employed, to create both symmetric and asymmetric two axis compensatory tracking tasks. All tasks were single loop on each axis. Analysis showed that a model that allocates control attention through nonlinear urgency functions using only error information could not achieve performance of the full model whose attention shifting algorithm included both error and error rate terms. Subsequent to this analysis, tracking performance predictions for the full model were verified by piloted flight simulation. Complete model and simulation data are presented

Maximum normalized acceleration as a flying qualities parameter

In 1984, Maximum Normalized Rate (MNR) was presented as a Flying Qualities parameter. Subsequent analysis of data from ground based simulation and flight test revealed the utility of a companion parameter, Maximum Normalized Acceleration (MNA). MNR and MNA profiles reveal the presence of both continuous and pulsed compensation strategies during discrete attitude tracking. In addition, MNR appears to be a suitable metric for pilot opinion in the LATHOS data base, while the MNR/MNA relationship is sensitive to pilot-induced-oscillation (PIO) and roll ratcheting problems. As part of an investigation of this problem, Northrop has developed an analysis technique known as the Step Target Method. The Step Target method is essentially a one degree-of-freedom simulation, where an attitude command in the form of a step function is presented to a closed-loop pilot/aircraft model. The two parameters MNR and MNA were shown to be useful in Flying Qualities analysis. MNR was shown to correlate with Pilot Opinion Rating in the LATHOS data base, while MNA reflects PIO and roll ratcheting. Profiles of MNR versus MNA reveal the presence of pulsed compensation strategies in both ground based and in-flight simulation. Furthermore, comparison of continuous and discrete attitude tracking simulation data reveals that these two tracking tasks exhibit independent sensitivities to aircraft characteristics

Maximum Normalized Rate as a Flying Qualities Parameter

Discrete attitude commands have become a standard task for flying qualities evaluation and control system testing. Much pilot opinion data is now available for ground-based and in-flight simulations, but adequate performance measures and prediction methods have not been established. The Step Target Tracking Prediction method, introduced in 1978, correlated time-on-target and rms tracking data with NT-33 in-flight longitudinal simulations, but did not employ parameters easily measured in manned flight and simulation. Recent application of the Step Target Tracking Prediction method to lateral flying qualities analysis has led to a new measure of performance. This quantity, called Maximum Normalized Rate (MNR), reflects the greatest attitude rate a pilot can employ during a discrete maneuver without excessive overshoot and oscillation. MNR correlates NT-33 lateral pilot opinion ratings well, and is easily measured during flight test or simulation. Futhermore, the Step Target MNR method can be used to analyze large amplitude problems concerning rate limiting and nonlinear aerodynamics

Challenges for Coring Deep Permafrost on Earth and Mars

This is the published version. Final publication is available from Mary Ann Liebert, Inc., publishers http://www.dx.doi.org/10.1089/ast.2007.0159.A scientific drilling expedition to the High Lake region of Nunavut, Canada, was recently completed with the goals of collecting samples and delineating gradients in salinity, gas composition, pH, pe, and microbial abundance in a 400 m thick permafrost zone and accessing the underlying pristine subpermafrost brine. With a triple-barrel wireline tool and the use of stringent quality assurance and quality control (QA/QC) protocols, 200 m of frozen, Archean, mafic volcanic rock was collected from the lower boundary that separates the permafrost layer and subpermafrost saline water. Hot water was used to remove cuttings and prevent the drill rods from freezing in place. No cryopegs were detected during penetration through the permafrost. Coring stopped at the 535 m depth, and the drill water was bailed from the hole while saline water replaced it. Within 24 hours, the borehole iced closed at 125 m depth due to vapor condensation from atmospheric moisture and, initially, warm water leaking through the casing, which blocked further access. Preliminary data suggest that the recovered cores contain viable anaerobic microorganisms that are not contaminants even though isotopic analyses of the saline borehole water suggests that it is a residue of the drilling brine used to remove the ice from the upper, older portion of the borehole. Any proposed coring mission to Mars that seeks to access subpermafrost brine will not only require borehole stability but also a means by which to generate substantial heating along the borehole string to prevent closure of the borehole from condensation of water vapor generated by drilling. Astrobiology 8, 623–638

Ancestral absence of electron transport chains in Patescibacteria and DPANN

© The Author(s), 2020. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Beam, J. P., Becraft, E. D., Brown, J. M., Schulz, F., Jarett, J. K., Bezuidt, O., Poulton, N. J., Clark, K., Dunfield, P. F., Ravin, N. V., Spear, J. R., Hedlund, B. P., Kormas, K. A., Sievert, S. M., Elshahed, M. S., Barton, H. A., Stott, M. B., Eisen, J. A., Moser, D. P., Onstott, T. C., Woyke, T., & Stepanauskas, R. Ancestral absence of electron transport chains in Patescibacteria and DPANN. Frontiers in Microbiology, 11, (2020): 1848, doi:10.3389/fmicb.2020.01848.Recent discoveries suggest that the candidate superphyla Patescibacteria and DPANN constitute a large fraction of the phylogenetic diversity of Bacteria and Archaea. Their small genomes and limited coding potential have been hypothesized to be ancestral adaptations to obligate symbiotic lifestyles. To test this hypothesis, we performed cell–cell association, genomic, and phylogenetic analyses on 4,829 individual cells of Bacteria and Archaea from 46 globally distributed surface and subsurface field samples. This confirmed the ubiquity and abundance of Patescibacteria and DPANN in subsurface environments, the small size of their genomes and cells, and the divergence of their gene content from other Bacteria and Archaea. Our analyses suggest that most Patescibacteria and DPANN in the studied subsurface environments do not form specific physical associations with other microorganisms. These data also suggest that their unusual genomic features and prevalent auxotrophies may be a result of ancestral, minimal cellular energy transduction mechanisms that lack respiration, thus relying solely on fermentation for energy conservation.This work was funded by the USA National Science Foundation grants 1441717, 1826734, and 1335810 (to RS); and 1460861 (REU site at Bigelow Laboratory for Ocean Sciences). RS was also supported by the Simons Foundation grant 510023. TW, FS, and JJ were funded by the U.S. Department of Energy Joint Genome Institute, a DOE Office of Science User Facility supported under Contract No. DE-AC02-05CH11231. NR group was funded by the Russian Science Foundation (grant 19-14-00245). SS was funded by USA National Science Foundation grants OCE-0452333 and OCE-1136727. BH was funded by NASA Exobiology grant 80NSSC17K0548

Deep subsurface mine stalactites trap endemic fissure fluid Archaea, Bacteria, and Nematoda possibly originating from ancient seas

Stalactites (CaCO3 and salt) from water seeps are frequently encountered in ceilings of mine tunnels whenever they intersect water-bearing faults or fractures. To determine whether stalactites could be mineralized traps for indigenous fracture water microorganisms, we analyzed stalactites collected from three different mines ranging in depth from 1.3 to 3.1 km. During sampling in Beatrix gold mine (1.4 km beneath the surface), central South Africa, CaCO3 stalactites growing on the mine tunnel ceiling were collected and observed, in two cases, to contain a living obligate brackish water/marine nematode species, Monhystrella parvella. After sterilization of the outer surface, mineral layers were physically removed from the outside to the interior, and DNA extracted. Based upon 16S and 18S rRNA gene sequencing, Archaea, Bacteria, and Eukarya in different combinations were detected for each layer. Using CT scan and electron microscopy the inner structure of CaCO3 and salt stalactites were analyzed. CaCO3 stalactites show a complex pattern of lamellae carrying bacterially precipitated mineral structures. Nematoda were clearly identified between these layers confirming that bacteria and nematodes live inside the stalactites and not only in the central straw. Salt stalactites exhibit a more uniform internal structure. Surprisingly, several Bacteria showing highest sequence identities to marine species were identified. This, together with the observation that the nematode M. parvella recovered from Beatrix gold mine stalactite can only survive in a salty environment makes the origin of the deep subsurface colonization enigmatic. The possibility of a Permian origin of fracture fluids is discussed. Our results indicate stalactites are suitable for biodiversity recovery and act as natural traps for microorganisms in the fissure water long after the water that formed the stalactite stopped flowing

A broad spectral, interdisciplinary investigation of the electromagnetic properties of sea ice

This paper highlights the interrelationship of research completed by a team of investigators and presented in the several individual papers comprising this Special Section on the Office of Naval Research (ONR), Arlington, VA, Sponsored Sea Ice Electromagnetics Accelerated Research Initiative (ARI). The objectives of the initiative were the following: 1) understand the mechanisms and processes that link the morphological and physical properties of sea ice to its electromagnetic (EM) characteristics; 2) develop and verify predictive models for the interaction of visible, infrared, and microwave radiation with sea ice; 3) develop and verify inverse scattering techniques applicable to problems involving the interaction of EM radiation with sea ice. Guiding principles for the program were that all EM data be taken with concurrent physical property data (salinity, density, roughness, etc.) and that broad spectral data be acquired in as nearly a simultaneous fashion as possible. Over 30 investigators participated in laboratory, field, and modeling studies that spanned the EM spectrum from radio to ultraviolet wavelengths. An interdisciplinary approach that brought together sea ice physicists, remote-sensing experts tin EM measurements), and forward and inverse modelers (primarily mathematicians and EM theorists) was a hallmark of the program. Along with describing results from experiments and modeling efforts, possible paradigms for using broad spectral data in developing algorithms for analyzing remote-sensing data in terms of ice concentration, age, type, and possibly thickness are briefly discussed