Tectonics of the central Andes

Acquisition of nearly complete coverage of Thematic Mapper data for the central Andes between about 15 to 34 degrees S has stimulated a comprehensive and unprecedented study of the interaction of tectonics and climate in a young and actively developing major continental mountain belt. The current state of the synoptic mapping of key physiographic, tectonic, and climatic indicators of the dynamics of the mountain/climate system are briefly reviewed

an individual participant data meta-analysis

Background The impact of neuraminidase inhibitors (NAIs) on influenza-related pneumonia (IRP) is not established. Our objective was to investigate the association between NAI treatment and IRP incidence and outcomes in patients hospitalised with A(H1N1)pdm09 virus infection. Methods A worldwide meta- analysis of individual participant data from 20 634 hospitalised patients with laboratory-confirmed A(H1N1)pdm09 (n = 20 021) or clinically diagnosed (n = 613) ‘pandemic influenza’. The primary outcome was radiologically confirmed IRP. Odds ratios (OR) were estimated using generalised linear mixed modelling, adjusting for NAI treatment propensity, antibiotics and corticosteroids. Results Of 20 634 included participants, 5978 (29·0%) had IRP; conversely, 3349 (16·2%) had confirmed the absence of radiographic pneumonia (the comparator). Early NAI treatment (within 2 days of symptom onset) versus no NAI was not significantly associated with IRP [adj. OR 0·83 (95% CI 0·64–1·06; P = 0·136)]. Among the 5978 patients with IRP, early NAI treatment versus none did not impact on mortality [adj. OR = 0·72 (0·44–1·17; P = 0·180)] or likelihood of requiring ventilatory support [adj. OR = 1·17 (0·71–1·92; P = 0·537)], but early treatment versus later significantly reduced mortality [adj. OR = 0·70 (0·55–0·88; P = 0·003)] and likelihood of requiring ventilatory support [adj. OR = 0·68 (0·54–0·85; P = 0·001)]. Conclusions Early NAI treatment of patients hospitalised with A(H1N1)pdm09 virus infection versus no treatment did not reduce the likelihood of IRP. However, in patients who developed IRP, early NAI treatment versus later reduced the likelihood of mortality and needing ventilatory support

Impact of neuraminidase inhibitors on influenza A(H1N1)pdm09‐related pneumonia: an individual participant data meta‐analysis

BACKGROUND: The impact of neuraminidase inhibitors (NAIs) on influenza‐related pneumonia (IRP) is not established. Our objective was to investigate the association between NAI treatment and IRP incidence and outcomes in patients hospitalised with A(H1N1)pdm09 virus infection. METHODS: A worldwide meta‐analysis of individual participant data from 20 634 hospitalised patients with laboratory‐confirmed A(H1N1)pdm09 (n = 20 021) or clinically diagnosed (n = 613) ‘pandemic influenza’. The primary outcome was radiologically confirmed IRP. Odds ratios (OR) were estimated using generalised linear mixed modelling, adjusting for NAI treatment propensity, antibiotics and corticosteroids. RESULTS: Of 20 634 included participants, 5978 (29·0%) had IRP; conversely, 3349 (16·2%) had confirmed the absence of radiographic pneumonia (the comparator). Early NAI treatment (within 2 days of symptom onset) versus no NAI was not significantly associated with IRP [adj. OR 0·83 (95% CI 0·64–1·06; P = 0·136)]. Among the 5978 patients with IRP, early NAI treatment versus none did not impact on mortality [adj. OR = 0·72 (0·44–1·17; P = 0·180)] or likelihood of requiring ventilatory support [adj. OR = 1·17 (0·71–1·92; P = 0·537)], but early treatment versus later significantly reduced mortality [adj. OR = 0·70 (0·55–0·88; P = 0·003)] and likelihood of requiring ventilatory support [adj. OR = 0·68 (0·54–0·85; P = 0·001)]. CONCLUSIONS: Early NAI treatment of patients hospitalised with A(H1N1)pdm09 virus infection versus no treatment did not reduce the likelihood of IRP. However, in patients who developed IRP, early NAI treatment versus later reduced the likelihood of mortality and needing ventilatory support

Technical note: preliminary slung load investigation on the Bell 412 advanced systems research aircraft

Recent flight tests were conducted on The National Research Council of Canada Flight Research Laboratory Bell 412 Advanced Systems Research Aircraft to investigate the effects of an externally slung load on helicopter dynamics and handling qualities. Results indicated that helicopter response to control inputs are reduced around the pendulum natural frequency of the slung load, and the bandwidth of the helicopter decreases. Helicopter handling qualities for the precision hover task are actually better with the slung load, however, load swing was not induced for this task.NRC publication: Ye

In-Flight Test Campaign to Validate PIO Detection and Assessment Tools

This paper describes a joint research campaign conducted by the German Aerospace Center (DLR) and the National Research Council Canada (NRC) to explore methods and techniques to expose rotorcraft Pilot-Induced Oscillations (PIOs) during flight testing. A flight test campaign was conducted at NRC using the Bell 205 experimental aircraft. Results show that, particularly for the lateral axis, ADS-33 tasks can be successfully applied to expose PIO tendencies. Novel subjective and objective criteria were used during the test campaign. PIO prediction boundaries of the objective phase-aggression criteria (PAC) detection algorithm were validated through results obtained. This was the first use of PAC with data recorded in-flight. To collect subjective feedback, the Aircraft Pilot Coupling (APC) scale was used. This was the first use of the novel scale in-flight and received favourable feedback from the evaluation pilot. Modifications to ADS-33 mission tasks were found to successfully improve the ability to consistently expose PIOs

The NRC Bell 412 ASRA safety system : a human factors perspective on lessons learned from an airborne incident

The National Research Council (NRC) Bell 205 Airborne Simulator is a full authority fly-by-wire (FBW) research helicopter. On 24 May, 1996 this aircraft underwent a failure which drove all four flight control actuators to full extension shortly after engagement of the FBW system, with nearly catastrophic results. The sound design inherent in the original Bell 205 safety system allowed the safety pilot to override the FBW system and prevented the loss of aircraft and crew. This incident, however, led to the realization that the existing safety system configuration in the Bell 205 was only marginally acceptable, and that this same system would be inadequate for the next generation FBW aircraft, the NRC Bell 412 Advanced Systems Research Aircraft (ASRA). Experience gained from the Bell 205 incident, and historical experience, has driven the design process of the safety systems for ASRA, with a particular view toward the capabilities and limitations of the operators.Peer reviewed: YesNRC publication: Ye

Bell 412 System Identification and Model Fidelity Assessment for Hover and Forward Flight

Frequency domain system identification of higher order models for the Bell 412 helicopter was performed. First, a frequency response database was derived from flight test data. For hover, a combination of sweep and 2311- multistep maneuvers had to be used to achieve good results. The identified hover model includes besides the classical 6-DoF rigid body states, as extension inflow and coning dynamics and uses a Padé approximation for the influence of engine dynamics, to improve the response in the vertical axis. The forward flight (60 kt) model includes as extension first order flapping dynamics, mainly to improve the roll and pitch response. Besides the simple Padé approach used in the hover model, two different engine model structures were investigated but they provided no significant improvement compared to the Padé solution when coupled to the rigid-body model. Finally a method derived from feedforward principles of model following control is shown, to use the identified hover model to analytically derive an "input filter" correction that improves the fidelity of a linearized FLIGHLAB simulation model

Bell 412 System Identification and Model Fidelity Assessment for Hover and Forward Flight

Frequency domain system identification of higher order models for the Bell 412 helicopter was performed. First, a frequency response database was derived from flight-test data. For hover, a combination of sweep and 2311-multistep maneuvers had to be used to achieve good results. In addition to the classical six-DoF (degrees of freedom) rigid body states, the identified hover model includes dynamic inflow, rotor coning dynamics, and uses a Padé approximation for the influence of engine dynamics, to improve the response in the vertical axis. The forward flight (60 kn) model includes as extension first-order flapping dynamics, mainly to improve the roll and pitch response. Besides the simple Padé approach used in the hover model, two different engine model structures were investigated but they provided no significant improvement compared to the Padé solution when coupled to the rigid-body model. Finally, a method derived from feedforward principles of model following control is shown, to use the identified hover model to analytically derive an "input filter" correction that improves the fidelity of a linearized FLIGHTLAB simulation model

Evaluation of Rotorcraft Pilot Induced Oscillations (PIO): Results from a DLR/NRC Collaborative Project

Pilot-induced oscillations (PIOs) still pose a significant risk to safety of rotorcraft operations, particularly as no formal evaluations are conducted during test and evaluation programs. Usually during experimental flight testing if PIOs are observed, additional testing and evaluations are conducted. This paper details results from a joint research effort undertaken by researchers at the National Research Center Canada (NRC) and the German Aerospace Center (DLR) to investigate and test novel methods and techniques to assess PIOs occurring in rotorcraft. The efforts included modifications to test processes and the use of PIO detection and prediction criteria. The research was conducted using both a ground-based simulation facility and a research helicopter. Results of the campaign showed the suitability of a novel subjective assessment scale and a PIO detection algorithm. This was confirmed through both objective and subjective assessment. Furthermore, modifications to ADS-33 mission task elements were also considered to improve the applicability to testing for PIOs

In-Flight Test Campaign to Validate PIO Detection and Assessment Tools

This paper describes a joint research campaign conducted by the German Aerospace Center (DLR) and the National Research Council Canada (NRC) to explore methods and techniques to expose rotorcraft Pilot-Induced Oscillations (PIOs) during flight testing. A flight test campaign was conducted at NRC using the Bell 205 experimental aircraft. Particularly for the lateral axis, ADS-33 tasks can be successfully applied to expose PIO tendencies. Novel subjective and objective criteria were used during the test campaign. PIO prediction boundaries of the objective phase-aggression critieria (PAC) detection algorithm were validated through results obtained. This was the first use of PAC with data recorded in-flight. To collect subjective feedback, the aircraft pilot coupling (APC) scale was used. This was the first use of the novel scale in-flight and received favorable feedback from the evaluation pilot. Modifications to ADS-33 mission tasks were found to successfully improve the ability to consistently expose PIOs