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Papiliotrema laurentii 5307AH was isolated from an aircraft polymer-coated surface. The genome size is 19,510,785 bp with a G + C content of 56%. The genome harbors genes encoding oxygenases, cutinases, lipases, and enzymes for styrene degradation, all of which could play a critical role in survival on xenobiotic surfaces.

Methane is a major contributor to anthropogenic greenhouse gas emissions. Identifying large sources of methane, particularly from the oil and gas sectors, will be essential for mitigating climate change. Aircraft-based methane sensing platforms can rapidly detect and quantify methane point-source emissions across large geographic regions, and play an increasingly important role in industrial methane management and greenhouse gas inventory. We independently evaluate the performance of five major methane-sensing aircraft platforms: Carbon Mapper, GHGSat-AV, Insight M, MethaneAIR, and Scientific Aviation. Over a 6 week period, we released metered gas for over 700 single-blind measurements across all five platforms to evaluate their ability to detect and quantify emissions that range from 1 to over 1,500 kg(CH4)/h. Aircraft consistently quantified releases above 10 kg(CH4)/h, and GHGSat-AV and Insight M detected emissions below 5 kg(CH4)/h. Fully blinded quantification estimates for platforms using downward-facing imaging spectrometers have parity slopes ranging from 0.76 to 1.13, with R2 values of 0.61 to 0.93; the platform using continuous air sampling has a parity slope of 0.5 (R2 = 0.93). Results demonstrate that aircraft-based methane sensing has matured since previous studies and is ready for an increasingly important role in environmental policy and regulation.

Hydrogen (H2) combustion and solid oxide fuel cells (SOFCs) can potentially reduce aviation-produced greenhouse gas emissions compared to kerosene propulsion. This paper outlines a methodology for evaluating performance and emission tradeoffs when retrofitting conventional kerosene-powered aircraft with lower-emissionH2 combustion and SOFC hybrid alternatives. The proposed framework presents a constant-range approach for designing liquid hydrogen fuel tanks, considering insulation, sizing, center of gravity, and power constraints. A lifecycle assessment evaluates greenhouse gas emissions and contrail formation effects for carbon footprint mitigation, while a cost analysis examines retrofit implementation consequences. A Cessna Citation 560XLS+ case study shows a 5% mass decrease for H2 combustion and a 0.4% mass decrease for the SOFC hybrid, at the tradeoff of removing three passengers. The lifecycle analysis of green hydrogen in aviation reveals a significant reduction in CO2 emissions for H2 combustion and SOFC systems, except for natural-gas-produced H2 combustion, when compared to Jet-A fuel. However, this environmental benefit is contrasted by an increase in fuel cost per passenger-km for green H2 combustion and a rise for natural-gas-produced H2 SOFC compared to kerosene. The results suggest that retrofitting aircraft with alternative fuels could lower carbon emissions, noting the economic and passenger capacity tradeoffs.

The lack of high vertical resolution atmospheric thermodynamic structure observations inside or near major weather events impedes our understanding of physical processes and their predictability in numerical weather prediction (NWP) models. Airborne Global Navigation Satellite System (GNSS) radio occultation (airborne radio occultation [ARO]) has proven to be a viable remote sensing option to offer dense soundings near flight tracks. The global fleet of commercial aircraft already equipped with GNSS receivers could be leveraged to produce an unprecedented number of ARO soundings along global flight paths. Eleven cases of atmospheric bending angle and refractivity profiles were successfully retrieved and compared with the colocated European Center for Medium‐Range Weather Forecasting global reanalysis data. Good quality measurements are obtained with median refractivity differences less than 1% in the middle and upper troposphere, between 5.5 and 11.5 km. Given the use of aircraft data (e.g., Aircraft Meteorological DAta Relay) for data assimilation, incorporating ARO profiles would be a valuable addition, further enhancing the accuracy of aviation and weather forecasts. Plain Language Summary: Global Navigation Satellite System radio occultation (RO) can be used to obtain vertical profiles of atmospheric conditions. This study shows how position data from commercial aircraft with existing hardware can be used to retrieve vertical profiles of atmospheric thermodynamic conditions (such as temperature, pressure, and humidity). Preliminary results show that high‐quality RO profiles can be extracted from unaltered aircraft information with low biases in the middle‐ and upper‐troposphere. The large number of commercial aircraft fleets could offer dense thermodynamic profiles in addition to the in‐situ observations to be operationally assimilated into global numerical weather prediction models, and greatly enhance regional model forecasts. Key Points: For the first time, Global Navigation Satellite System (GNSS) radio occultation (RO) profiles from commercial aircraft with no purpose‐built science payload were extractedGood quality RO profiles are retrievable from commercial closed‐loop GNSS receivers onboard aircraft between flight level and 4 km above mean‐sea‐levelCommercial aircraft could offer thermodynamic profiles along with observations to be assimilated into numerical weather prediction models, and enhance forecasts [ABSTRACT FROM AUTHOR]

Introduction Rotating shiftwork schedules are known to disrupt sleep in a manner that can negatively impact safety. Consumer sleep technologies (CSTs) may be a useful tool for sleep tracking, but the standard feedback provided by CSTs may not be salient to shift-working populations. SleepTank is an app that uses the total sleep time data scored by a CST to compute a percentage that equates hours of sleep to the fuel in a car and warns the user to sleep when the "tank" is low. Royal Australian Navy aircraft maintenance workers operating on a novel rotational shift schedule were given Fitbit Versa 2s to assess sleep timing, duration, and efficiency across a 10-week period. Half of the participants had access to just the Fitbit app while the other half had access to Fitbit and the SleepTank app. The goal of this study was to evaluate differences in sleep behavior between shifts using an off-the-shelf CST and to investigate the potential of the SleepTank app to increase sleep duration during the 10-week rotational shift work schedule. Materials and Methods Royal Australian Navy volunteers agreed to wear a Fitbit Versa 2 with the SleepTank app (SleepTank condition), or without the SleepTank app (Controls), for up to 10 weeks from May to July 2023 during the trial of a novel shift rotation schedule. Participants from across 6 units worked a combination of early (6:00 AM to 2:00 PM), day (7:30 AM to 4:30 PM), late (4:00 PM to 12:00 AM), and night shifts (12:00 AM to 6:00 AM) or stable day shifts (6:00 AM to 4:00 PM). Differences in sleep behavior (time in bed, total sleep time, bedtime, wake time, sleep efficiency [SE]) between conditions and shift types were tested using Analysis of Variance. This study was approved by the Australian Departments of Defence and Veterans' Affairs Human Research Ethics Committee. Results Thirty-four participants completed the full study (n  = 17 Controls; n  = 17 SleepTank). There was a significant effect of shift type on 24-hour time in bed (TIB24; F(4,9) = 8.15, P  < .001, η2 = 0.15) and total sleep time (TST24; F(4,9) = 8.54, P  < .001, η2 = 0.18); both were shorter in early shifts and night shifts compared to other shift types. TIB24 and TST24 were not significantly different between conditions, but there was a trend for greater SE in the SleepTank condition relative to Controls (F(1,9) = 2.99, P  = .08, η2 = 0.11). Conclusions Sleep data collected by Fitbit Versa 2s indicated shorter sleep duration (TIB24, TST24) for Royal Australian Navy workers during early and late shifts relative to stable day shifts. Access to the SleepTank app did not greatly influence measures of sleep duration but may be protective against fatigue by affecting SE. Further research is needed to evaluate the utility of the SleepTank app as a means of improving sleep hygiene in real-world, shift-working environments. [ABSTRACT FROM AUTHOR]

The evaluation of the comfort of landing operations through pilot scores may be a viable quality indicator to be adopted in airport runway management. However, some factors, such as the aircraft model, can influence this perception. This paper aims to evaluate the physical characteristics of aircraft that affect the pilots' assessment related to comfort during landing operations at runways. We analyzed 11 runways with different conditions of roughness and measured using the International Roughness Index (IRI), associated with the scores given by pilots in the same runways. In addition, we performed a statistical analysis of four physical characteristics of the aircraft: wingspan, length, base, and gauge. The results indicate a relationship between pilot scores and runway roughness, where the gauge is the physical characteristic with the greatest influence on pilot scores. More specifically, for IRI values between 2.0 and 2.5 m/km , these characteristics influenced the perception, with better comfort during landings attributed to smaller aircraft. [ABSTRACT FROM AUTHOR]

This study proposes a probabilistic model to assess the likelihood of passenger survival in fires resulting from aircraft accidents. The model evaluates the risk of passenger death in a fire, considering the type of aircraft and airline. By comparing the time available for passengers to fully evacuate a burning plane with the time required for evacuation using modern means and technologies, onboard rescue equipment, and the qualifications of crew members and rescue personnel, we introduce a comprehensive approach to quantify passenger survival rates. Additionally, the concept of the hazard coefficient is introduced, which accounts for factors such as cabin temperature and toxic components. [ABSTRACT FROM AUTHOR]

With touchscreens being installed in aircraft flight decks, reach-and-turbulence-related challenges arise. Using the ISO 9241-411 multidirectional selection task (a 2D Fitts' task), we quantified the impact of vibration on touchscreen target selection throughput (a performance score combining both speed and accuracy) and error rate in a cockpit layout. 24 participants completed the task under 2 vibration levels (helicopter level flight versus static), 2 hand support methods (using the thumb, while holding onto the screen's edge, versus using the index finger freehand), 4 touchscreen types (two avionic and two consumer touchscreens), 2 touchscreen positions (main instrument panel versus pedestal), and 4 target sizes (0.8, 1, 1.5 and 2 cm). We found average throughput values of 6.5 bits per second (bps) in static conditions, versus 5.7 bps under vibration, and average error rates of 10.3% in static conditions, versus 16.6% under vibration. Similar to prior work, we found an exponential increase in error rate with decreasing target size. Larger target sizes helped mitigate the impact of vibration. We did not find evidence of a benefit to anchoring the hand on the touchscreen's bezel edge, compared to the freehand baseline, under vibration or static conditions. Under vibration, the pedestal outperformed the main instrument panel position, with higher throughput and lower error rate. In static conditions, the two positions performed similarly. This work contributes to vibration mitigation methods when interacting with touchscreens in the aviation context. [ABSTRACT FROM AUTHOR]

The integrated design of a variable cycle engine (VCE) and an aircraft thermal management system (TMS) is investigated. The integrated system is designed using the multiple design point approach in order to achieve required performance metrics at points other than the cycle design condition. The VCE architecture is a three stream design where the third stream is split off after the fan, exhausting through a separate third-stream nozzle. The primary air stream passes through a low-pressure compressor before splitting into an inner bypass stream and a core stream. The inner streams mix aft of the low-pressure turbine and exhaust through a core nozzle. The variable cycle engine utilizes variable compressor inlet guide vanes, a variable area bypass injector at the core stream mixing plane, and variable throats in the two exhaust nozzles. The TMS architecture is an air cycle system using air bled from the high-pressure compressor. The effect of integrating the TMS into the engine design loop is investigated. A comparison is made to prior studies where the same TMS architecture was connected to a low bypass ratio turbofan engine. The comparison shows that the variable cycle engine is able to improve heat dissipation capability versus a ram air cooled system, while eliminating the airframe integration impact that comes with a separate ram-air stream. Lastly, the impact of modulating the variable geometry features on overall cooling capability is investigated. Results are presented for individual operating points as well as at the aircraft mission level. [ABSTRACT FROM AUTHOR]

Aircraft encounters with volcanic ash have caused significant damage over the past 40 years, resulting in particular attention being given to the issue. We analyzed the volcanic ash-aircraft encounter database published by the USGS. We added new volcanic eruptions and parameters such as eruption types, and dry–wet. Then, we applied standard and advanced statistical methods. Over 130 encounters have been documented in the mentioned database, with volcanic ash causing severe abrasions to the windshield, airframe, wings, and engine components. In nine cases, aircraft engines failed. We applied the binary regression analysis and some laboratory melting experiments on volcanic ash. Besides phreatomagmatism, we use the term external water in this work to describe meteoric water that enters volcanic plumes through precipitation or melting ice on ice-capped volcanoes. We demonstrated that engine failure occurs when our regression analyses undergo dry-to-wet conditions. In other words, statistically, there is a positive correlation between wet ash encounters with aircraft and engine failure incidents. Moreover, experiments conducted at 900 °C and under 40 bar pressure showed increased sintering in the dry sample, while melting textures were more prevalent in hydrated samples. We concluded that despite the various eruptive dynamics of volcanic ash, the introduction of external water into the volcanic plumes, probably causing instantaneous hydration of volcanic ash, is a common factor in engine failure incidents. Thus, we have identified the reasons behind engine failures during encounters between aircraft and volcanic ash and the specific damage that can occur depending on the type of eruption involved. [ABSTRACT FROM AUTHOR]

The problem of crystal ice formation inside aircraft turbine engines is well‐documented, and poses a significant risk to safety. The problem is not only one of power loss in flight, but the very real possibility that a flame‐out event could occur due to ice accretion on compressor stators, with potentially catastrophic outcomes. Although many instrumentation systems have been developed for wing ice detection, incipient formation of crystal ice is somewhat more difficult to detect. This is compounded by the need for a noncontact sensor which is robust to in‐flight conditions. This paper proposes an approach to the detection of ice formation based on microwave transmission characteristics across the first and possibly the second stage of the compressor stator. It is shown that noncontact detection is feasible under realistic conditions. The contribution of this paper is twofold. First, the microwave transmission approach is motivated using wind tunnel measurements, and appropriate frequency bands are determined. Next, a signal processing approach involving higher‐order analysis of time‐frequency distribution characteristics is then put forward. Experimental results are presented to support the hypothesis that multiband detection offers a workable approach to the incipient crystal‐ice detection problem. [ABSTRACT FROM AUTHOR]

The design of the space hatch door mechanisms is crucial in the aerospace field, impacting not only durability and reliability but also the life safety of astronauts during space missions. This review extensively researches vehicle doors and hatches in civil and military systems across various environments, including land, sea, deep sea, aviation, aerospace, and extreme conditions. Specially, it focuses on the structural design of hatches and related mechanisms in civil aviation and military aerospace environments, such as opening and closing mechanisms, release mechanisms, locking mechanisms, sealing mechanisms, and the ergonomic design of door structures. The review highlights the integration of bionic design principles with hatch mechanisms to explore future solutions. By systematically examining these aeras, this review addresses the lack of comprehensive studies in previous reviews, which often overlook the interconnectivity and applicability of hatch mechanisms across different fields. The absence of such holistic reviews has led to fragmented knowledge and missed opportunities for cross-industry innovation. This review aims to fill these gaps by providing a wide range of design solutions and offering insights that can enhance the development of more reliable, efficient, and safe hatch mechanisms in aerospace and other high-stakes environments. [ABSTRACT FROM AUTHOR]

This study focuses on the dynamics of the profit margin within the aviation MRO industry, using operational data from a small and medium-sized enterprise (SME) MRO company between 2013 and 2021. Especially in SME MROs, profit margin analysis provides an advantage in competing with the large companies that dominate the industry. Therefore, the operational data were prepared for analysis to identify the variables related to the profit margin. This study's data cleaning and transformation processes can serve as a guideline for similarly sized companies. The research aims to address the complex relationships among the factors influencing profit margins in this industry. The objective is to utilise these factors in making strategic decisions to increase the profit margin of an SME MRO company. Applying gradient boosting algorithms as the analytical framework should allow identifying the correct relationships between the profit margin and input variables according to time for the SME MRO company. Another important aspect of this study is to increase the accuracy of the gradient boosting model by utilising the interactive grouping methodology. The variable selection was performed by using the Gini indexes of the variables using interactive grouping as a criterion in selecting the variables to be included in the model. After the data cleaning, transformation, and selection, the input variables for the gradient boosting model were Part Description, Parts Billed Current (part cost), Labour Billed Current (labour cost), Diff Shipping Entry (turnaround time (TAT)), Diff Quote Entry (time to quotation (TTQ)), Manager, Department, and Status. In this study, the profitability model indicates that the SME MRO company should initially focus on part numbers and the departments, secondly on standardisation of and expertise in preferred workshop units, and lastly, on highly qualified and effective technical department leaders and increasing labour. The aviation industry emerges as a sector that requires such analytical studies. It is hoped that the study will serve as a foundational work for SME MRO companies in the aviation industry. [ABSTRACT FROM AUTHOR]

Wind tunnel tests are costly and time-consuming, and the accuracy of the tests is limited by the size of the tunnel, to solve this problem, researchers use computational fluid dynamics (CFD) to conduct wind tunnel experiments using a computer because it is less timely and less costly. Computerized testing of drone's models using wind tunnel experiment simulation in computational fluid dynamic (CFD) software requires knowledge of the most suitable turbulence model for this drone. In this paper ANSYS fluent program has been used to test four most common turbulence models for use (Spalart-Allmaras, K-Epsilon, K-Omega and Reynolds stress) and laminar flow on the ScanEagle drone model (an aerial reconnaissance drone used in military and intelligence operations) and calculated their effect on aerodynamic parameters In terms of accuracy and time to solution, concluded that the best turbulence model in terms of balancing accuracy and the time taken for the calculation is K-Omega model. [ABSTRACT FROM AUTHOR]

Current research on apron conflict detection is often limited to the interaction between the aircraft as a whole and other objects, making it difficult to accomplish targeted identification of vulnerable and high‐cost aircraft components. However, the implementation of detailed aircraft identification is of great significance to enhance the safety of airport surface operations. Based on the excellent performance of High‐Resolution Network (HRNet) in keypoint detection, a lightweight end‐to‐end keypoint detection network, namely Squeeze and Excitation High‐Resolution Network (SEHRNet), is proposed in this paper to solve the problems of HRNet's slower computation and more redundancy. First, the errors arising from coordinate transformations in the coding and decoding process are solved by an improved feature map coding and decoding process. Second, replace the BasicBlock in HRNet with the Depthwise separable convolutions based on the Squeeze‐and‐Excitation Networks, which drastically cuts the computational cost of the network. Third, the improved Bottleneck module is used to further enhance the capability of feature extraction. Experimental results prove that, based on the aircraft keypoint detection dataset, the SEHRNet proposed in this paper shows stronger applicability compared to the current mainstream networks. Compared with the original HRNet, the improved network has higher accuracy, faster speed, and lighter model for aircraft keypoint detection. [ABSTRACT FROM AUTHOR]

Unmanned aircraft are usually used to perform missions, for example surveillance missions. This mission is not always carried out in a suitable location. Researchers must ensure that the aircraft can take off properly. For this reason, runway distance greatly affects the performance of the aircraft. The aircraft can fail to take off due to the lack of thrust generated by the propeller. The propeller diameter size of each unmanned aircraft can differ from one another and this difference in propeller diameter causes a difference in thrust force. Therefore, it is very important to determine the right propeller diameter to be used on an unmanned aircraft that is adjusted to the runway distance. This propeller selection analysis is carried out using experimental methods, which is tool testing and simulation with Propeller Power Calculator software. The results of this study can be seen that a propeller with a larger diameter will produce a greater thrust force. The size of the diameter and pitch and the number of blades of a propeller can also affect the amount of thrust generated. This will be a consideration for choosing a propeller to be used on an unmanned aircraft. So that the selected propeller can be used optimally by reviewing the amount of thrust that is influenced by the amount of diameter. [ABSTRACT FROM AUTHOR]

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This article introduces a comprehensive Mode-S radar simulation, designed to evaluate interrogation and reply signal functionality in various uplink formats (UFs) and downlink formats (DFs). Mode-S radar, crucial in modern aviation, facilitates communication between aircraft and ground systems, thereby enhancing aircraft tracking, situational awareness, and air traffic safety. Our simulation focuses on optimizing interrogation and reply sequences in the 1030- and 1090-MHz channels, respectively. It provides a practical solution for testing complex air flight scenarios, which may be impractical or costly in real life, by replicating challenging conditions in a computerized environment. This approach aids in developing advanced radar signaling algorithms for air traffic control. The simulator’s user-friendly interface displays real-time aircraft data, demonstrating its realworld applicability. Its successful operation underscores its potential to advance Mode-S radar technology and its value for research in the field. [ABSTRACT FROM AUTHOR]

Modeling dispersion of aircraft emissions is challenging because aircraft are mobile sources with varying emissions rates at different elevations depending on the operating mode. Aircraft emissions during landing and take-off cycle (LTO) influence air quality in and around the airport, and depending on the number of aircraft operations and location of the airport, this influence may be significant. AERMOD (v22112) incorporates a variety of conventional source types to characterize the intended emissions source, leaving the question of which conventional source type(s) best characterizes aircraft activities across the four modes of LTO cycle, unanswered. Currently, the publicly released version of FAA's Aviation Environmental Design Tool (version 3e) models aircraft emissions as a set of AREA sources for all flight segments. A research version of AEDT allows users to model aircraft sources—both fixed wing and rotorcraft—as a series of VOLUME sources in AERMOD. However, both source treatments do not account for plume rise of aircraft jet exhaust. This paper compares AERMOD's performance in describing SO2 concentrations associated with airport sources by comparing model results from the two source options during the summer campaign of the Air Quality Source Apportionment study conducted at the Los Angeles International Airport. We conclude that both VOLUME source and AREA treatments overestimate the highest observed SO2 concentrations despite not accounting for background sources. The VOLUME source option reduces this overestimation by using a higher initial plume spread than the AREA option does, and through the inclusion of meander. Our results suggest the need to include the plume rise of jet exhaust when using AERMOD for airport air quality studies. [ABSTRACT FROM AUTHOR]

The subject of this work is the development of a nonlinear model of the interaction of an unsteady fluid flow with a structure and finding analytical solutions for the system of equations that correspond to the specified model. The convection effect of the fluid velocity field was already considered in the previous works of the authors of this paper. These studies are devoted to the water hammer without considering the "flow-structure" interaction. This work expands the possibilities of modeling and considers four equations instead of two equations of the theory of the water hammer (equations of conservation of mass and momentum), two of which relate to the motion of particles of a solid body (pipes or structures). The novelty of this work lies in the consideration of the model that describes the interaction of the flow with the structure, the convection in the velocity field, and the effect, together with the friction of the fluid against the solid wall, on the dynamics of the shock pulse propagation process both in the fluid and in the solid body. It should be noted that the solution of the nonlinear system of differential equations as a whole is carried out by an analytical method, which makes it possible to obtain an exact (rather than numerical) solution of the problem. Since the effects of various factors should be evaluated by comparison with the main components, dimensionless equations containing six parameters (dimensionless combinations) were obtained in this study. Two of these parameters were named after scientists – Darcy and Weisbach (steady friction) and Bruno (unsteady friction). Particular cases of the general (full) model were considered, and the effects of various factors on the dynamics of the interaction of the flow with the structure during the propagation of the shock pulse were determined. Research methods are purely theoretical. The concepts of a self-similar equation and a system of equations, balances of forces acting on particles of a fluid and a solid body, and a standard method of reducing a system of equations to a single equivalent equation are used. Conclusions. An extended model of the interaction between the unsteady fluid flow and the structure is proposed. The transition to a self-similar variable makes it possible to solve a nonlinear system of differential equations and obtain an analytical (exact) solution. The functions of longitudinal stress in a solid body, pressure disturbance, and velocity of motion of particles in a solid body (pipe) are linearly expressed by the velocity of shock pulse propagation in the fluid. It should also be noted that the results for the particular case of the linear model completely agree with the already known ones. The advantage of using a self-similar solution is that it is easy to obtain. The results of previous studies on the water hammer problem were qualitatively consistent. As the fluid viscosity increases, the shock pulse domain becomes more concentrative.

High Mach flight has put forward more stringent requirements for the material and structure design of new generation of high-speed vehicles. This paper reviews the application of ceramic matrix composites（CMCs） in the structural design of aircraft from the aspects of selection，application，and evaluation，and then the future development direction is put forward to provide reference for aircraft ceramic matrix composite structure design. The selection criteria and corresponding preparation methods of CMCs in different application scenarios are comprehensively reviewed，the typical applications of CMCs in aircraft structures are systematically introduced，and the evaluation criteria and ground test methods of the materials under near-service conditions are analyzed. To order to meet the future demands of aircraft，it is necessary to integrate computer-aided optimization technology and innovative preparation methods to enhance the temperature resistance and fatigue performance of CMCs. Developing highly reliable，long-life joining techniques and integrated design solutions will fully leverage the advantages of these materials. Additionally，in-situ characterization techniques under multi-physical field coupling need to be developed to obtain the performance evolution behaviour of CMCs in actual use，providing a reliable basis for the lightweight structural design of aircraft.

The tendency to self-oscillations is one of the most important problems of closed-loop hydraulic systems. In actual systems losses occur, variation of the transmitted energy and the strength of the system structural elements are always limited. This is the reason why self-oscillations are most often present. The main purpose of the research is to reveal the mechanisms of instability and self-oscillations in an electro-hydraulic servo drive to make a numerical simulation of the drive characteristics. A servo drive has all the conditions for the generation of self-oscillations: the oscillatory element – the movable member of the drive and a column of elastic liquid, the source of energy. Regular oscillations in a drive are maintained due to the energy of compressed liquid, feedback, non-linear character of generated and absorbed energy etc. An experimental analysis of a servo system of the FESTO training simulator was carried out. The aim of the research was to accumulate materials for the development of mathematical models that would adequately represent the main properties of actual systems.

Abstract Current research on apron conflict detection is often limited to the interaction between the aircraft as a whole and other objects, making it difficult to accomplish targeted identification of vulnerable and high‐cost aircraft components. However, the implementation of detailed aircraft identification is of great significance to enhance the safety of airport surface operations. Based on the excellent performance of High‐Resolution Network (HRNet) in keypoint detection, a lightweight end‐to‐end keypoint detection network, namely Squeeze and Excitation High‐Resolution Network (SEHRNet), is proposed in this paper to solve the problems of HRNet's slower computation and more redundancy. First, the errors arising from coordinate transformations in the coding and decoding process are solved by an improved feature map coding and decoding process. Second, replace the BasicBlock in HRNet with the Depthwise separable convolutions based on the Squeeze‐and‐Excitation Networks, which drastically cuts the computational cost of the network. Third, the improved Bottleneck module is used to further enhance the capability of feature extraction. Experimental results prove that, based on the aircraft keypoint detection dataset, the SEHRNet proposed in this paper shows stronger applicability compared to the current mainstream networks. Compared with the original HRNet, the improved network has higher accuracy, faster speed, and lighter model for aircraft keypoint detection.

BACKGROUND: There is increasing evidence for adverse health effects associated with aircraft-emitted particulate matter (PM) exposures, which are largely in the ultrafine (PM0.1) size fraction, but no previous study has examined neurodevelopmental outcomes. OBJECTIVE: To assess associations between maternal exposure to aircraft ultrafine particles (UFP) during pregnancy and offspring autism spectrum disorder (ASD) diagnosis. METHODS: This large, representative cohort study included 370,723 singletons born in a single healthcare system. Demographic data, maternal health information, and childs ASD diagnosis by age 5 were extracted from electronic medical records. Aircraft exposure estimates for PM0.1 were generated by the University of California Davis/California Institute of Technology Source Oriented Chemical Transport model. Cox proportional hazard models were used to assess associations between maternal exposure to aircraft PM0·1 in pregnancy and ASD diagnosis, controlling for covariates. RESULTS: Over the course of follow-up, 4,554 children (1.4 %) were diagnosed with ASD. Increased risk of ASD was associated with maternal exposure to aircraft PM0.1 [hazard ratio, HR: 1.02, (95 % confidence interval (CI): 1.01-1.03) per IQR = 0.02 µg/m3 increase during pregnancy. Associations were robust to adjustment for total PM0.1 and fine particulate matter (PM2.5), near-roadway air pollution, and other covariates. Noise adjustment modestly attenuated estimates of UFP effects, which remained statistically significant. DISCUSSION: The results strengthen the emerging evidence that maternal particulate matter exposure during pregnancy is associated with offspring ASD diagnosis and identify aircraft-derived PM0.1 as novel targets for further study and potential regulation.

A novel integrated gas turbine cycle design and power management optimization methodology for parallel hybrid electric propulsion architectures is presented in this paper. The gas turbine multipoint cycle design method is extended to turboprop and turbofan architectures, and several trade studies are performed initially at the cycle level. It is shown that the maximum degree of electrification is limited by the surge margin levels of the booster in the turbofan configuration. An aircraft mission-level assessment is then performed using the integrated optimization method initially for an A320 Neo style aircraft case. The results indicate that the optimal cycle redesigned hybrid electric propulsion system (HEPS) favors takeoff and climb power on-takes while optimal retrofit HEPS favor cruise power on-takes. It is shown that for current battery energy density (250 Wh/Kg), there is no fuel burn benefit. Furthermore, even for optimistic energy density values (750 Wh/kg) the maximum fuel burn benefit for a 500 nm mission is 5.5% and 4% for redesigned and retrofit HEPS, respectively. The power management strategies for HEPS configurations also differ based on gas turbine technology with improvement in gas turbine technology showing greater scope for electrification. The method is then extended to ATR 72 style aircraft case, showing greater fuel burn benefits across the flight mission envelope. The power management strategies also change depending on the objective function, and optimum strategies are reported for direct operating cost or fuel burn. The retrofit case studies show a benefit in direct operating cost compared to redesigned case studies for ATR 72. Finally, a novel multimission approach is shown to highlight the overall fuel burn and direct operating cost benefit across the aircraft mission cluster. [ABSTRACT FROM AUTHOR]

Abstract Air travel has an important role in the spread of viral acute respiratory infections (ARIs). Aircraft offer an ideal setting for the transmission of ARI because of a closed environment, crowded conditions, and close-contact setting. Numerous studies have shown that influenza and COVID-19 spread readily in an aircraft with one virus-positive symptomatic or asymptomatic index case. The numbers of secondary cases differ markedly in different studies most probably because of the wide variation of the infectiousness of the infector as well as the susceptibility of the infectees. The primary risk factor is sitting within two rows of an infectious passenger. Elite athletes travel frequently and are thus prone to contracting an ARI during travel. It is anecdotally known in the sport and exercise medicine community that athletes often contract ARI during air travel. The degree to which athletes are infected in an aircraft by respiratory viruses is unclear. Two recent studies suggest that 8% of Team Finland members traveling to major winter sports events contracted the common cold most probably during air travel. Further prospective clinical studies with viral diagnostics are needed to understand the transmission dynamics and to develop effective and socially acceptable preventive measures during air travel.

The subject of this work is the phenomenon of a water hammer in a liquid that contains a small volume of gas bubbles. Historically, this phenomenon began to be studied as the dynamics of gas bubbles (Rayleigh-Pleset equation). Today, thanks to progress in computer technology, this phenomenon is studied at the level of bubble deformation during hydraulic shock. Another approach is to consider the dynamics of a multiphase (two-phase) medium in the form of a bubbly liquid. After several assumptions, the main one being a relatively small gas content in the liquid, the model consists of two differential equations with respect to the shock wave propagation speed and the resulting pressure perturbations. The specified system of equations differs from the corresponding classical water hammer equations: they consider the convection of the velocity field. In addition, the friction of the liquid against the wall according to the Weisbach-Darcy model is considered. Because of the small content of gas bubbles, the Weissbach-Darcy friction is approximated in the same way as in a homogeneous liquid, i.e., in a certain sense, greater than the real friction. Maybe that is why more or less physical results are obtained only for small values of the dimensionless parameter responsible for the friction of the liquid against the wall. It concerns the non-contradiction of the assumptions and the results obtained on their basis. Thus, in the front region of the shock pulse, where the pressure increases, the radial velocity of the bubbles is negative; however, for relatively large values of the friction parameter, the maximum pressure disturbance moves from the center of the shock pulse. This contradicts the assumption about compression: after passing the maximum pressure, gas bubbles expand due to a decrease in pressure. The graphical dependence obtained in this study are compared with the results related to a homogeneous liquid. They agree, but the shock pulse in a bubbly liquid is not as concentrated in space as that in a homogeneous liquid. Its length is 10-12 times greater than the corresponding value in a homogeneous liquid. Research methods are purely theoretical. The well-known bubble liquid model is used as a single-speed model continuum. Differential equations are solved analytically, approximately (series expansion), and numerically. In addition, the original approach of obtaining an analytical solution of an autonomous system is used-finding the function of pressure disturbances from the velocity of propagation of the shock pulse (and vice versa). Conclusions. A simple one-dimensional hydraulic model of shock wave (impulse) propagation in a bubbly liquid is proposed. In contrast to classical ideas (solutions) about a water hammer, which consists of two waves of opposite directions of propagation, a shock pulse is a region of pressure disturbances in which the speed of motion of fluid particles is also variable – from the maximum value to almost zero.

The main purpose of the article is to identify the main approaches and define the concept when modeling the hydro-mechanical control systems of an aircraft. The advantages and importance of a computational experiment with the aid of a virtual test bed at the stage of constructive parametric debugging of the elements of complex hydraulic systems are emphasized. The characteristics obtained from the results of the computational experiment will allow us to determine the level of adequacy of the models and subsequently choose the most optimal design and operational parameters.

The primary objective of this study is to investigate the specific aspects of psychological resilience among ARFF professionals. Utilizing a qualitative approach and collecting data from 11 ARFF professionals using semi-structured interviews, this study delves into an exploration of factors that contribute to psychological resilience among Aircraft Rescue and Firefighting (ARFF) personnel stationed at State Airports, a group operating under emergency circumstances within the aviation industry. The investigation reveals three overarching themes: micro-level personal factors, meso-level organizational factors, and macro-level environmental/societal factors. Key findings reveal that micro-level personal factors, including personality traits and individual coping mechanisms, significantly influence ARFF professionals' psychological resilience. Encompassing leadership quality and team dynamics, meso-level organizational factors have emerged as crucial contributors to resilience. Finally, macro-level environmental/societal factors, such as social support networks and the broader emergency preparedness context, have been identified as integral elements shaping psychological resilience. This qualitative approach, designed to capture the nuanced experiences and perceptions of ARFF professionals through a multi-level exploration of psychological resilience, extends its implications to the realms of aviation and emergency response. Micro-level considerations illuminate the significance of human resources-related decisions, such as recruitment and training, in fortifying ARFF professionals' resilience. Meso-level considerations provide evidence for the impactful role of leadership and effective safety measures in promoting resilience. Macro-level considerations underscore the importance of environmental design and spillover effects, such as family support, in shaping resilience. An understanding of the factors that contribute to psychological resilience may be directly transferable to the creation of support mechanisms and targeted interventions and may also be directly transferable to assist emergency response teams in the aviation sector. [ABSTRACT FROM AUTHOR]

This paper reports on the archaeological recording and recovery of a MK II Fairey Barracuda from the Solent, Hampshire, off the south coast of England. As its location precluded the aircraft being left in situ, the decision was made to recover the aircraft. Despite adverse visibility, and a significant amount of overburden, the extant remains of the aircraft were successfully recovered and delivered to the Fleet Air Arm Museum for conservation, as part of an ongoing project to rebuild an example of a Fairey Barracuda. In being recovered for reuse and exhibition some of the Barracuda's value to the wider community changed from that of a lost military aircraft to that of an historic object, drawing out the social history around it, and giving insights into military aircraft construction during the World War II. [ABSTRACT FROM AUTHOR]

The article considers multi-component and multi-stage mathematical models of queuing systems (QS) with the distribution of the incoming flow simultaneously between the system components, which consist of a certain number of service channels and waiting places in the queue. The maintenance of requirements with a lack of time to stay in the service channel and waiting is considered, while the service process in the QS of each component consists of several stages with the corresponding duration, and the full-service period is equal to the sum of such time intervals. The number of components and their parameters correspond to the similar characteristics of the production divisions of the repair enterprise. The study of the effectiveness of the operation of the repair enterprise as a multi-component and multi-stage QS consists in determining the values of the initial parameters of the QS components, taking into account the restrictions imposed on them, in order to obtain the largest values of the probabilities of servicing the requirements of the QS components and the system as a whole. The model is implemented using Any Logic University Researcher, which allows you to combine the principles of system dynamics with the paradigms of agent and discrete-event modelling. The proposed approach to the modelling of maintenance and repair processes by production divisions of the enterprise as a multi-component and multi-phase QS allows to determine the effectiveness of the functioning of such a QS and to obtain arguments for increasing the efficiency of its operation. [ABSTRACT FROM AUTHOR]

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