MH370 Controlled Eastward Veering and Descent After the 6th Arc

Past expert analyses of communication signals from missing Malaysian Airlines MH370 reconciled Burst Frequency Offset (BFO) errors up to the 6th of 7 arcs for a southerly track. After the 6th arc, the Satellite Data Unit (SDU) power-up or reboot resulted in settling errors in the last two data points that were ignored (first search) and later bounded (second search). For the second search, investigators invoked a high-speed vertical descent to account for BFO errors for the south track fuel-starved scenario. Two searches disappointingly failed to find the implied violent-crash site. We report that interpretations were flawed in suggesting the plane dived vertically, as investigators did not recognize that BFO extrapolations implicitly implied mathematically that the plane was also cruising along the south track, but with no fuel. Our reanalysis used the “Penang Longitude” (PL) theory that predicted a similar southerly track to the 6th arc, and that MH370 subsequently veered eastwards and descended. Doppler Shifts from vertical motions were replaced with plausible horizontal veering and declination of a high-speed aircraft. Veering predicted by the PL theory plus controlled descent plausibly accounts for nominal 7th arc BFO discrepancies for the warm-reboot scenario. We conclude that the fuel-starvation scenario analyses wrongly implied a vertical high-speed crash that ignored the impossible implicit southerly cruise, with no fuel, assumption. Instead, MH370 was piloted to a precise glide landing under power, east of the 7th arc.

Early On-Set Prediction Of Vortex-Ring State Of Quadrotors

The OpenFOAM CFD package was used to initially investigate the aerodynamic effects of vortex-ring state of a quadrotor, then to study various quadrotor flight maneuvers to minimize the thrust loses of vortex-ring state and followed by possible detection methods for a drone entering vortex-ring state. Vortex-ring state is characteristic of a decrease in the effective angle of attack of incoming airflow due to a rotor descending into its downwash. This causes significant loses in the thrust of the rotor, which typically leads to severe flight upsets for rotorcraft. A quadrotor was studied at varying descent velocities to investigate wake roll-up at the rotor tips and the subsequent effects on rotor thrust and power. The quadrotor was then subjected to non-vertical descent angles to investigate thrust loss mitigation approaches due to vortex-ring state. A method of detecting the on-set of vortex-ring state is proposed using various differential pressure measurements on the quadrotor. It has been shown that by monitoring the pressure difference between the top of the quadrotor body and the bottom of one of the quadrotor legs, a pressure drop can be seen just prior to the on-set of vortex-ring state. This pressure drop was shown to occur during descending flight regimes and may prove to be an effective pre-vortex-ring state warning system.

Early On-Set Prediction Of Vortex-Ring State Of Quadrotors

The OpenFOAM CFD package was used to initially investigate the aerodynamic effects of vortex-ring state of a quadrotor, then to study various quadrotor flight maneuvers to minimize the thrust loses of vortex-ring state and followed by possible detection methods for a drone entering vortex-ring state. Vortex-ring state is characteristic of a decrease in the effective angle of attack of incoming airflow due to a rotor descending into its downwash. This causes significant loses in the thrust of the rotor, which typically leads to severe flight upsets for rotorcraft. A quadrotor was studied at varying descent velocities to investigate wake roll-up at the rotor tips and the subsequent effects on rotor thrust and power. The quadrotor was then subjected to non-vertical descent angles to investigate thrust loss mitigation approaches due to vortex-ring state. A method of detecting the on-set of vortex-ring state is proposed using various differential pressure measurements on the quadrotor. It has been shown that by monitoring the pressure difference between the top of the quadrotor body and the bottom of one of the quadrotor legs, a pressure drop can be seen just prior to the on-set of vortex-ring state. This pressure drop was shown to occur during descending flight regimes and may prove to be an effective pre-vortex-ring state warning system.

Geospatial distributions reflect temperatures of linguistic features

Quantifying the speed of linguistic change is challenging because the historical evolution of languages is sparsely documented. Consequently, traditional methods rely on phylogenetic reconstruction. Here, we propose a model-based approach to the problem through the analysis of language change as a stochastic process combining vertical descent, spatial interactions, and mutations in both dimensions. A notion of linguistic temperature emerges naturally from this analysis as a dimensionless measure of the propensity of a linguistic feature to undergo change. We demonstrate how temperatures of linguistic features can be inferred from their present-day geospatial distributions, without recourse to information about their phylogenies. Thus, the evolutionary dynamics of language, operating across thousands of years, leave a measurable geospatial signature. This signature licenses inferences about the historical evolution of languages even in the absence of longitudinal data.

Response of colonial Peruvian guano birds to flying UAVs: effects and feasibility for implementing new population monitoring methods

Background Drones are reliable tools for estimating colonial seabird numbers. Although most research has focused on methods of improving the accuracy of bird counts, few studies have evaluated the impacts of these methods on bird behavior. In this study, we examined the effects of the DJI Phantom 3 drone approach (altitude, horizontal and vertical descent speeds) on changes in the intensity of behavioral response of guano birds: guanay cormorants (Phalacrocorax bougainvilli), Peruvian boobies (Sula variegata) and Peruvian pelicans (Pelecanus thagus). The breeding and non-breeding condition was also evaluated. Methods Eleven locations along the Peruvian coast were visited in 2016–2017. Drone flight tests considered an altitude range from 5 to 80 m from the colony level, a horizontal speed range from 0.5 to 15 m/s, and a vertical descent speed range from 0.5 to 3 m/s. The intensity of the behavioral response of birds was scored and categorized as: 0-no reacting, 1-head pointing to the drone (HP), 2-wing flapping (WF), 3-walking/running (WR) and 4-taking-off/flying (TK). Drone noise at specific altitudes was recorded with a sound meter close to the colony to discriminate visual from auditory effects of the drone. Results In 74% of all test flights (N = 507), guano birds did not react to the presence of the drone, whereas in the remaining flights, birds showed a sign of discomfort: HP (47.7%, N = 130), WF (18.5%), WR (16.9%) and TK (16.9%). For the drone approach tests, only flight altitude had a significant effect in the intensity of the behavioral response of guano birds (intensity behavioral response <2). No birds reacted at drone altitudes above 50 m from the colony. Birds, for all species either in breeding or non-breeding condition, reacted more often at altitudes of 5 and 10 m. Chick-rearing cormorants and pelicans were less sensitive than their non-breeding counterparts in the range of 5–30 m of drone altitude, but boobies reacted similarly irrespective of their condition. At 5 m above the colony, cormorants were more sensitive to the drone presence than the other two species. Horizontal and vertical flights at different speeds had negligible effects (intensity behavioral response <1). At 2 m above the ground, the noise of the cormorant colony was in average 71.34 ± 4.05 dB (N = 420). No significant differences were observed in the drone noise at different flight altitudes because the background noise of the colony was as loud as the drone. Conclusions It is feasible to use the drone DJI Phantom 3 for surveys on the guano islands of Peru. We recommend performing drone flights at altitudes greater than 50 m from guano bird colonies and to select take-off spots far from gulls. Likewise, this study provides a first step to develop guidelines and protocols of drone use for other potential activities on the Peruvian guano islands and headlands such as surveys of other seabirds and pinnipeds, filming and surveillance.

Investigation of nonlinear landing gear behavior and dynamic responses on high performance aircraft

The dynamic responses simulation of aircraft as rigid body considering heave, pitch, and roll motions, coupled onto a tricycle landing gear arrangement is presented. Equation of motion for each landing gear consists of un-sprung mass vertical and longitudinal motions considering strut nonlinear stiffness and damping combined with strut bending flexibility. Initially, the nonlinear dynamic response model is subjected to an input of riding over staggered bump and the responses are compared with linear landing gear model. It is observed that aircraft dynamics and important landing gear events such as vertical, spin-up and spring-back are truly represented with nonlinear stiffness and damping model considering strut bending flexibility. Later, landing response analysis is performed, with the input from nonlinear flight mechanics model for several vertical descent rate cases. The aircraft and landing gear dynamic responses such as displacement, velocity, acceleration, and reaction forces are obtained. The vertical and longitudinal drag forces from the nonlinear dynamic response model is compared with “Book-case method” outlined in landing gear design technical specifications. From the reaction force ratio calculation, it is shown that for lower vertical descent rate case the predicted loads are lesser using nonlinear dynamic response model. The same model for higher vertical descent rate cases predicts higher ratios on vertical reaction for main landing gear and longitudinal reaction for nose landing gear, respectively. The scope for increase in fatigue life for low vertical descent rate landing covering major design spectrum and the concern for static strength and structural integrity consideration for higher vertical descent rate cases are discussed in the context of event monitoring on aircraft in services.

Transient Replication in Specialized Cells Favors Conjugative Transfer of a Selfish DNA Element

Bacterial evolution is driven to a large extent by horizontal gene transfer (HGT) – the processes that distribute genetic material between species rather than by vertical descent. HGT is mostly mediated by an assortment of different selfish DNA elements, several of which have been characterized in great molecular detail. In contrast, very little is known on adaptive features optimizing horizontal fitness. By using single DNA molecule detection and time-lapse microscopy, we analyze here the fate of an integrative and conjugative element (ICE) in individual cells of the bacteriumPseudomonas putida. We uncover how the ICE excises and irregularly replicates, exclusively in a sub-set of specialized host cells. As postulated, ICE replication is dependent on its origin of transfer and its DNA relaxase. Rather than being required for ICE maintenance, however, we find that ICE replication serves more effective conjugation to recipient cells, providing selectable benefit to its horizontal transfer.