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Supersonic jet noise, a significant concern in military and civilian aerospace due to its impact on aircraft operability, environmental compliance, and community noise standards, drives the need for studies on jet mixing to optimize processes and reduce noise emissions effectively. This study presents the design and development of a Mach 1.6 nozzle, designed to evaluate the jet decay, directional spread and noise attenuation character. Incorporated at the nozzle exit are two rectangular tabs, with perforation angles of zero and 30 degrees. These tabs, with a blockage ratio of 0.09, are strategically positioned to modify the exhaust flow pattern. Experimental analyses, inclusive of jet decay and acoustic assessments, were conducted at a nozzle pressure ratio of 4.25, corresponding to optimal expansion conditions. Observations were made on the centerline pressure decay along the jet axis and the lateral jet spreading for baseline and controlled jets. Utilizing the Schlieren optical method, the shockwave structures were visualized to understand the flow physics. The results indicated a substantial reduction in the length of the potential core, amounting to 65.13% and 80.76% for zero- and thirty-degrees perforation angles, respectively, compared to an unmodified baseline jet. Moreover, as compared to the baseline jet the 30 degrees perforation configuration demonstrated a significant 9 dB reduction in jet noise. [ABSTRACT FROM AUTHOR]

Background: Previous studies reported an association between transportation noise and self-reported health status (SRHS). They also suggested a mediating role of noise annoyance using conventional statistical methods. These methods are subject to bias in longitudinal studies with time-dependent exposure, mediator and confounding factors. This study aims to investigate the mediating role of aircraft noise annoyance in the effect of aircraft noise on SRHS using a causal inference approach to address time-dependent variables issues. Methods: We used data from 881 participants in all three visits in the DEBATS longitudinal study conducted around three French airports. Participants over 18 years of age reported their self-perceived health status, aircraft noise annoyance, and noise sensitivity by completing a questionnaire at three visits in 2013, 2015 and 2017. Noise maps were used to estimate aircraft noise levels outside their homes. Marginal structural models with inverse probability weighting were used to estimate the total effect of aircraft noise levels on SRHS and its decomposition into direct and indirect effect through aircraft noise annoyance. Results: This study showed a deleterious effect of aircraft noise on SRHS. The odds ratio (OR) corresponding to the total effect and comparing the highest aircraft noise category (≥60 dBA) to the reference category (<50 dBA) was significant (ORpoor/fair_SHRS = 1.25 (95%CI: 1.06 to 2.08)). It also showed no direct effect of aircraft noise levels on SRHS, but an indirect effect through annoyance. This indirect effect increased as aircraft noise levels increased, with a statistically significant OR when comparing the highest noise category (≥60 dBA) to the lowest (<50 dBA) (ORpoor/fair_SHRS = 1.16 (95%CI: 1.03 to 1.52)). Nearly 66% of aircraft noise's effect on SRHS was mediated by aircraft noise annoyance. Conclusion: This study supports the deleterious causal effect of aircraft noise on SRHS. The results highlight the important mediating role of aircraft noise annoyance in the causal pathway from exposure to aircraft noise to poor/fair SRHS. [ABSTRACT FROM AUTHOR]

This document discusses the emerging fields of environmental and climate cardiology, which focus on the impact of environmental and climate changes on cardiovascular health. It highlights reports from the World Health Organization and the Global Burden of Disease study that emphasize the consequences of unhealthy environments, including millions of deaths attributed to cardiovascular causes and pollution-related diseases. The document also mentions the association between climate change-related events, like extreme heat, and increased cardiovascular risks. It suggests steps to increase research and awareness in this field, such as forming task forces, promoting educational programs, and improving epidemiological studies. Additionally, it proposes the idea of a new health discipline combining environmental and climate cardiology to benefit individuals and populations. [Extracted from the article]

Abstract Background Long-term exposure to transportation noise is related to cardio-metabolic diseases, with more recent evidence also showing associations with diabetes mellitus (DM) incidence. This study aimed to evaluate the association between transportation noise and DM mortality within the Swiss National Cohort. Methods During 15 years of follow-up (2001–2015; 4.14 million adults), over 72,000 DM deaths were accrued. Source-specific noise was calculated at residential locations, considering moving history. Multi-exposure, time-varying Cox regression was used to derive hazard ratios (HR, and 95%-confidence intervals). Models included road traffic, railway and aircraft noise, air pollution, and individual and area-level covariates including socio-economic position. Analyses included exposure-response modelling, effect modification, and a subset analysis around airports. The main findings were integrated into meta-analyses with published studies on mortality and incidence (separately and combined). Results HRs were 1.06 (1.05, 1.07), 1.02 (1.01, 1.03) and 1.01 (0.99, 1.02) per 10 dB day evening-night level (Lden) road traffic, railway and aircraft noise, respectively (adjusted model, including NO2). Splines suggested a threshold for road traffic noise (~ 46 dB Lden, well below the 53 dB Lden WHO guideline level), but not railway noise. Substituting for PM2.5, or including deaths with type 1 DM hardly changed the associations. HRs were higher for males compared to females, and in younger compared to older adults. Focusing only on type 1 DM showed an independent association with road traffic noise. Meta-analysis was only possible for road traffic noise in relation to mortality (1.08 [0.99, 1.18] per 10 dB, n = 4), with the point estimate broadly similar to that for incidence (1.07 [1.05, 1.09] per 10 dB, n = 10). Combining incidence and mortality studies indicated positive associations for each source, strongest for road traffic noise (1.07 [1.05, 1.08], 1.02 [1.01, 1.03], and 1.02 [1.00, 1.03] per 10 dB road traffic [n = 14], railway [n = 5] and aircraft noise [n = 5], respectively). Conclusions This study provides new evidence that transportation noise is associated with diabetes mortality. With the growing evidence and large disease burden, DM should be viewed as an important outcome in the noise and health discussion.

The use of magnetometers arranged in a gradiometer configuration offers a practical and widely used solution, particularly in archaeological applications where the sources of interest are generally shallow. Since magnetic anomalies due to archaeological remains often have low amplitudes, highly sensitive magnetic sensors are kept very close to the ground to reveal buried structures. However, the deployment of Unmanned Aerial Vehicles (UAVs) is increasingly becoming a reliable and valuable tool for the acquisition of magnetic data, providing uniform coverage of large areas and access to even very steep terrain, saving time and reducing risks. However, the application of a vertical gradiometer for drone-borne measurements is still challenging due to the instability of the system drone magnetometer in flight and noise issues due to the magnetic interference of the mobile platform or related to the oscillation of the suspended sensors. We present the implementation of a magnetic vertical gradiometer UAV system and its use in an archaeological area of Southern Italy. To reduce the magnetic and electromagnetic noise caused by the aircraft, the magnetometer was suspended 3m below the drone using ropes. A Continuous Wavelet Transform analysis of data collected in controlled tests confirmed that several characteristic power spectrum peaks occur at frequencies compatible with the magnetometer oscillations. This noise was then eliminated with a properly designed low-pass filter. The resulting drone-borne vertical gradient data compare very well with ground-based magnetic measurements collected in the same area and taken as a control dataset. [ABSTRACT FROM AUTHOR]

In order tomake detailed and accurate predictions of aircraft noise around airports, we have developed "J-FRAIN", a new aircraft noise simulation framework that can precisely predict the time histories of noises emitted from each major aircraft noise source during the landing approach phase at ground observation points. This article describes the elements of the developed framework--data acquisition, sound source modeling, propagation modeling, and ground noise prediction--and present some application examples. To develop the framework, we first deployed a 30m-diameter microphone array under the final approach path to an international airport to measure acoustic maps of several civil aircraft types in flight. The sound powers of major aircraft noise-emitting componentswere then estimated quantitatively by domain integration of the deconvolved acoustic maps at five emission angles in the plane of the glideslope, and the directivities of each noise sourcewere determined. Next, componentwise sound source regression models for engines and airframe noise sourceswere created based on the physical relationships between engine rotation speed, airspeed, and the deployment angle of high-lift devices, and the coefficients in each modelwere determined to minimize the root-mean-square error between themeasured and predicted sound power levels. The phenomena of atmospheric absorption and ground effect during the propagation of radiated sounds were also incorporated into the framework. Actual flight parameter values were used as inputs to the completed framework, and it was confirmed that the predicted time histories of sound pressure levels on the ground agreed with measured data towithin 2 dB if ground effect was properly considered. Finally, as sample applications that use the unique features of the proposed J-FRAIN framework, the article discusses the evaluation of the contributions of each aircraft noise source at noise observation points under the final approach path to the airport and the impact assessment of flight operations on noise. [ABSTRACT FROM AUTHOR]

One source of modern aircraft engine noise is the fan, which is especially noticeable during takeoff at high angular rotation speeds. In such modes, supersonic flow around the fan blades occurs, which leads to the formation of shock waves that propagate upstream until they exit the engine duct. As a result, specific noise is emitted into the front hemisphere, consisting of a number of harmonics that are multiples of the fan rotation frequency. The paper analyzes this effect using a simple model of the propagation of a system of shock waves. An energy approach is used to demonstrate that a system of shock waves with shocks of equal amplitude attenuates the most rapidly. [ABSTRACT FROM AUTHOR]

The Aeroacoustics Laboratory in the Department of Aerospace Engineering at Penn State currently serves several areas of experimental research. Most notable in the laboratory is the Anechoic Chamber of which the Aeroacoustics Wind Tunnel is an integral part. In recent years the dominant areas of research have included model aircraft exhaust jets and model rotors for helicopter applications involving detailed noise experiments. In the jet noise area, the applications have included aircraft in both flyover and take-off configurations. In the flyover application the air flow surrounding the exhaust jet has a significant effect on the radiated noise and must be simulated to produce experimental results that will be most useful in preliminary design of noise suppression applications. The Aeroacoustics Wind Tunnel at Penn State serves the purpose for this simulation. During aircraft take-off, the aircraft airspeed is in a range exceeding 250 ft per second, or Mach number of over M = 0.22. In the years preceding 2022, the velocity of the free jet flow of the Penn State facility was limited to less than 200 ft/sec. This paper reports on a project to design upgrades to the existing wind tunnel to improve the test section flow velocity to values closer to the 250 ft/sec target. The approach began with a preliminary design of the return flow ducting to convert the open jet, open return wind tunnel to a closed return tunnel. The concept is to make use of the flow energy in the exhaust of the tunnel to boost the input energy to the inlet fan that drives the flow to the test section. An integral part of the preliminary design involved making use of an upgraded flow analysis computer code to predict the gain in test section velocity of the new facility. For the available horsepower of two fans in the facility, the configurations of the existing and upgraded wind tunnel were entered into this analysis code based on a quasi-one-dimensional formulation. The code included empirical data formulated to include the various shapes of the components of the tunnels. The relative flow velocities in each section used simple incompressible continuity to calculate all velocities in the component sections. The average dynamic pressure in each section is calculated from the flow (constant) density and the velocity squared. Each section had a non-dimensional pressure loss parameter calculated from empirical data (from the relevant literature). The basic code (using the Excel algorithms) was based on a predictor-corrector concept in which the calculation was initialized with the estimated velocity and pressure of the flow at the entrance to the test section. The loss in each following section is estimated to determine the loss in the total pressure and the cumulated loss compared to the gains made at the two fans in the circuit. The initial guess is adjusted based on the total pressure value at the end of the circuit. During the related experiments, measurements of the total and dynamic pressure were performed at several joints between sections and compared to the values predicted in the analysis code. Various settings of the horsepower of the drive fans were used and the results were compared to flow measurements for the tunnel configurations (predominantly for the open return and closed return tunnel setups available before and after the upgrade project.) Results of the analysis and experiments are presented and analyzed together with the remaining activities planned for the coming months. [ABSTRACT FROM AUTHOR]

In India, railway is the major transportation mode for carrying goods and people. The tracks for the movement of the rail were initially constructed in the city for the pre-eminence and expediency of the vantage of the people. Rapid modernization and increasing population in the city crammed the area around the railway tracks. Moving rail on the tracks passing through the city is not compatible, which is creating problems for the nearby residents. In the urban and suburban regions, the railway noise has become a major problem. This study was conducted to examine the perception of the physiological and psychological effects of railway noise in the nearby areas of railway stations in Delhi, India. For this purpose, 10 sites near the railway station were selected for the study. To assess the impact of railway noise pollution on the health of humans, a questionnaire survey was conducted. The data of 344 individuals were collected through the questionnaire survey and analyzed to get the perception towards railway noise. Noise level was monitored by a Sound Level Meter (SLM) and the equivalent noise level (Leq) in dB(A) was used to compute the noise pollution in three shifts, i.e., morning, noon, and evening time. Results showed that 57.65% of female and 86.11% of male respondents in the survey reported the disturbance due to railway noise. The level of noise pollution was found higher in the evening time as compared to the noon and morning period, which exceeds the limit set by the Central Pollution Control Board (CPCB) at all the monitored locations. Findings of the study show that the primary cause of the health problems is railroad noise, which is negatively impacting the health of the residents, who are living in the proximity of the rail track region. The perception survey reported that headache, sleep disturbance, irritation, and stress are common health issues among the locals residing around the railway track proximity in Delhi. [ABSTRACT FROM AUTHOR]

Research on urban noises affecting acoustic communication of animals is a growing area of study and conservation concern. However, the consequences of aircraft noise on anuran acoustic communication have been explored on a restricted basis to date. In this study, we investigated the impact of aircraft overflights on the individual and chorus performance of acoustic signalling in the Pedregal frog (Eleutherodactylus grandis), a microendemic and threatened species from Mexico City. During the summer of 2021, we recorded acoustic signals from male individuals and conducted acoustic monitoring to analyse how chorus social interactions change due to aircraft overflights. For this purpose, we evaluated acoustic properties of the call, including call duration, dominant frequency, call amplitude, and call repetition rate. Additionally, we measured the amplitude of environmental noises and signals by means of two types of complementary methodological approaches. Our results show changes in the individual performance of acoustic signals with longer call duration, lower dominant frequency, and higher call amplitude due to aircraft overflights, while individual call repetition rate did not vary. Furthermore, a decrease in the number of calls within the chorus was observed during aircraft overflight. Overall, these results show that aircraft noise causes plastic changes in the acoustic signals of the Pedregal frog and that social interactions between conspecifics decrease, thus adding a new disturbance to this species that already suffers from other anthropogenic noises, and habitat fragmentation. [ABSTRACT FROM AUTHOR]

Air traffic has appreciable environmental impacts, especially regarding gaseous emissions and noise. Recent studies have shown that the energy management during approach is a driving factor regarding environmental impact and is especially challenging for pilots. In a previous project, a newly developed pilot assistance system called LNAS (Low Noise Augmentation System) showed the potential of energy-optimized approaches to reduce fuel consumption and noise. Within the SESAR Exploratory Research project DYNCAT, novel functions based on LNAS have been integrated in the flight management system. In this contribution, results from real-time simulations with the enhanced FMS are presented, and mitigation of the environmental impact is analyzed. It was shown that with DYNCAT, the energy management could be improved, resulting in a later configuration and engines mostly in idle. With DYNCAT, procedures were also flown more uniformly and the variability in noise and fuel outcomes was reduced. However, the results revealed a trade-off for optimizing noise and fuel consumption simultaneously, whereby both parameters can be improved along specific optimum curves. A perfect strategy to minimize noise would be to first reduce speed and only secondly height, as high speeds lead to higher levels of airframe noise and sound exposure increases with decreasing distance. In contrast, saving fuel might be achieved by reducing the flight time, as the engines consume fuel even when being in idle. [ABSTRACT FROM AUTHOR]

The traditional method of allocating passenger seats based on compartments does not effectively manage an aircraft's center of gravity (CG), resulting in a notable divergence from the desired target CG (TCG). In this work, the Boeing B737-800 aircraft was employed as a case study, and row-based and compartment-based integer programming models for passenger allocation were examined and constructed with the aim of addressing the current situation. The accuracy of CG control was evaluated by comparing the row-based and compartment-based allocation techniques, taking into account different bodyweights and numbers of passengers. The key contribution of this research is to broaden the range of the mobilizable set for the aviation weight and balance (AWB) model, resulting in a significant reduction in the range of deviations in the center of gravity outcomes by a factor of around 6 to 16. The effectiveness of the row-based allocation approach and the impact of passenger weight randomness on the deviation of an airplane's CG were also investigated in this study. The Monte Carlo method was utilized to quantify the uncertainty associated with passenger weight, resulting in the generation of the posterior distribution of the aircraft's center of gravity (CG) deviation. The outcome of the row-based model test is the determination of the range of passenger numbers that can be effectively allocated under different TCG conditions. [ABSTRACT FROM AUTHOR]

Background: Long-term exposure to transportation noise is related to cardio-metabolic diseases, with more recent evidence also showing associations with diabetes mellitus (DM) incidence. This study aimed to evaluate the association between transportation noise and DM mortality within the Swiss National Cohort. Methods: During 15 years of follow-up (2001–2015; 4.14 million adults), over 72,000 DM deaths were accrued. Source-specific noise was calculated at residential locations, considering moving history. Multi-exposure, time-varying Cox regression was used to derive hazard ratios (HR, and 95%-confidence intervals). Models included road traffic, railway and aircraft noise, air pollution, and individual and area-level covariates including socio-economic position. Analyses included exposure-response modelling, effect modification, and a subset analysis around airports. The main findings were integrated into meta-analyses with published studies on mortality and incidence (separately and combined). Results: HRs were 1.06 (1.05, 1.07), 1.02 (1.01, 1.03) and 1.01 (0.99, 1.02) per 10 dB day evening-night level (Lden) road traffic, railway and aircraft noise, respectively (adjusted model, including NO2). Splines suggested a threshold for road traffic noise (~ 46 dB Lden, well below the 53 dB Lden WHO guideline level), but not railway noise. Substituting for PM2.5, or including deaths with type 1 DM hardly changed the associations. HRs were higher for males compared to females, and in younger compared to older adults. Focusing only on type 1 DM showed an independent association with road traffic noise. Meta-analysis was only possible for road traffic noise in relation to mortality (1.08 [0.99, 1.18] per 10 dB, n = 4), with the point estimate broadly similar to that for incidence (1.07 [1.05, 1.09] per 10 dB, n = 10). Combining incidence and mortality studies indicated positive associations for each source, strongest for road traffic noise (1.07 [1.05, 1.08], 1.02 [1.01, 1.03], and 1.02 [1.00, 1.03] per 10 dB road traffic [n = 14], railway [n = 5] and aircraft noise [n = 5], respectively). Conclusions: This study provides new evidence that transportation noise is associated with diabetes mortality. With the growing evidence and large disease burden, DM should be viewed as an important outcome in the noise and health discussion. [ABSTRACT FROM AUTHOR]

An open-source simulation model for aircraft noise prediction is presented and validated using backpropagated noise measurements for a state-of-the-art engine and aircraft. The validation is focused on approach procedures and was performed using ground-based noise measurements that were taken at 17 recording stations for a total of 18 consecutive flights carried out during the morning of 8 April 2021. The flights were performed using two A321neo aircraft with LEAP-1A engines. It is demonstrated that the presented noise model provides a satisfactory estimation of the source noise for varying approach configurations and flight conditions. Configurations using a greater number of high-lift devices are particularly well predicted in the mid- and high-frequency regions, whereas the lower configuration settings show greater spectral deviations, which are partly attributed to measurement uncertainties caused by the increased aircraft-microphone distance. The model can predict the overall mean total sound intensity level within a 2 dB accuracy for all configurations, while the average predicted level at each microphone differs by less than 3 dB from the measurement average, for all cases except one. Variation in aircraft speed showed to have a strong impact on the predicted total noise, which matches the well-recognized sixth-power Mach number far-field sound intensity scaling law for airframe noise models, while the measurements indicated a less significant dependency. This is mainly due to installation effects and noise reduction measures that are not included in the models. Nevertheless, the variations in the spectra of the predicted and measured noise showed similar patterns. [ABSTRACT FROM AUTHOR]

A major challenge for the Air Traffic Management system is the need to boost airspace capacity, which is near saturation in some situations. Separation minima are one of the factors related to airspace capacity, and the SESAR program promotes research into advanced separation modes. Ad Hoc separation, a novel separation mode, involves applying different pairwise separation minima in the same volume of airspace depending on a set of factors, such as encounter geometry, aircraft models, and flight level, among others. This research examines the impact of implementing this concept in different en-route scenarios. The goal is to determine whether applying this concept proves advantageous or, conversely, results in an increase in the complexity of the system without significant benefits in the key performance areas of capacity, environment, and cost-efficiency. Fast Time Simulations are conducted in RAMS software, with the concept being implemented in the LECMZMU, LECMTLU, and LECMDGU sectors of the Madrid ACC. The results reveal favorable capacity outcomes with increases of around 2% and the LECMZMU sector exhibits the most significant environmental and cost-efficiency benefits. Furthermore, implementing the Ad Hoc concept in a larger scenario could yield even greater environmental and cost-efficiency benefits. [ABSTRACT FROM AUTHOR]

With rapid urbanization, traffic growth has accelerated in some cities in China. Due to strict urban construction land utilization policies, many high-rise apartment buildings have been constructed adjacent to expressways. To better understand the impact of urban traffic noise on the residents of high residential buildings adjacent to expressways and the differences in noise impacts on different floors, on-site noise monitoring and questionnaires for building residents have been conducted. The characteristics of traffic noise were analyzed based on the measured data, and factors, including time periods and building floors, were considered. According to the results of the questionnaire survey, 56.06% of the male respondents and 54.55% of the female respondents think that the impact of traffic noise on high-rise buildings is "high" or "very high"; 50.53% of the respondents who were in "good" or "very good" condition thought that the traffic noise has a "significant impact" or "very significant impact" on their sleep and daily life. In addition, 25% of respondents living on floors 4–10 and 62.5% of respondents living on floors 11–20 considered the traffic noise to have a "significant impact" or "very significant impact" on their sleep and daily life. The on-site noise monitoring results show that the noise levels (LAeq) outside the windows of the studied buildings remain significantly elevated, with daytime noise on working days ranging from 56 to 70 dB(A), and on weekends ranging from 50 to 65 dB(A). During the four time periods on weekdays from 7 a.m. to 9 a.m., 11 a.m. to 1 p.m., 5 p.m. to 7 p.m., and 10 p.m. to 12 a.m., the average LAeq levels on floors 11–20 are higher than those on floors 4–10 by 4.04 dB(A), 4.92 dB(A), 4.06 dB(A), and 2.67 dB(A), respectively. Similarly, during these time periods on weekends, the levels on floors 11–20 are higher than those on floors 4–10 by 4.96 dB(A), 6.32 dB(A), 5.28 dB(A), and 5.24 dB(A), respectively. This indicates that floors 4–10 of the building experience relatively lower noise levels, while floors 11–20 are subjected to comparatively higher levels of noise disturbance. [ABSTRACT FROM AUTHOR]

This article discusses the possibilities of reducing noise pollution in the vicinity of a selected airport, with an emphasis on practical measures. The proposed procedures, which are routinely employed at commercial airports, would be ineffective or financially unsustainable under the circumstances of the military airports. The objective at military airports is not to maximise capacity, as at civil airports, where the desire to increase capacity is primarily related to profit. The primary objective for military airports is to perform defined tasks, which may include pilot training, search and rescue exercises and combat training. The main measures proposed to reduce noise pollution in the vicinity of the villages are changes in departure and arrival routes, the splitting of night operations into two parts and the introduction of a new article in the AIP and Airport Regulations prohibiting air operations over and in close proximity to the villages nearby. Finally, it is stressed that a significant reduction in noise will only be possible with the support of changes in legislation or above-standard financial investment by the airport operator.

In densely populated cities, residents living near aerodromes may experience heightened exposure to aircraft noise. With hybrid work arrangement, authorities have observed a rise in the number of complaints filed by residents affected by aircraft noise. In view of this problem, urban planners are now placing even more emphasis on exploring solutions that can manage aircraft noise in new and existing residential areas. To achieve this objective, urban planners usually rely on external acoustic consultants to generate noise maps using commercial software. However, urban planners may need to quickly evaluate potential noise issues in the neighbourhood so that noise management strategies can be brainstormed in advance. In this article, we present the development and benchmarking of a package designed to easily generate aircraft noise maps via simplified procedures and a reduced amount of input data, with acceptable accuracy in the results. These benefits distinguish our developed package from commercial software. Our developed package was eventually integrated into an in-house-developed unified urban environmental modelling tool that aims to help urban planners design more liveable and sustainable residential towns in an intuitive and quick manner.

With the widespread application of drone technology, energy management of drone swarms has become a key challenge in ensuring sustained and efficient operations. To optimize the energy consumption of drone swarms, researchers have proposed the energy balance plane routing algorithm. This algorithm uses ultraviolet light for low visibility communication and has shown promising results in managing the energy of drone swarms. To address the issues of uneven cluster head distribution and reduced energy consumption in other algorithms, an improved non-uniform clustering energy balancing routing algorithm is proposed. Compared to existing algorithms, the improved non-uniform clustering energy balancing routing algorithm achieved the lowest average communication consumption among 5 nodes and prolonged node failure time. The performance of the research method has been verified through simulation experiments, which is of great significance in maintaining energy consumption balance and can improve the energy efficiency and sustainability of the network. This study can provide more effective solutions for the development and application of drone technology, promoting its widespread application and promotion in various fields. [ABSTRACT FROM AUTHOR]

X-rays have been observed in natural downward cloud-to-ground lightning for over 20 years and in rocket-triggered lightning for slightly less. In both cases, this energetic radiation has been detected during the stepped and dart leader phases of downward negative flashes. More recently, X-rays have also been reported during the dart leader phase of upward negative flashes. In this study, we present the observations of four upward positive lightning flashes from the Säntis Tower (2.5 km ASL) in Switzerland. These consist of the simultaneous records of electric current passing through the tower, and electric field strength and X-ray flux 20 m from the tower base. One of the flashes was captured by a high-speed camera operating at 24,000 frames per second, stills from which are also presented. We detected X-rays during the initial phase of upward negative leader propagation, which can be associated with the leader-stepping process from electric field and current waveforms. To the best of our knowledge, this is the first time that such measurements are reported in the literature. The obtained time-synchronised data confirm that the X-ray emissions detected are associated with the initial steps of the upward negative leader. The frequency and energy of X-ray pulses appear to decrease as functions of time, with pulses disappearing altogether within the first millisecond of the leader initiation. X-ray emission also appears to be correlated with the maximum current-derivative and the electric field change of leader steps, consistent with cold electron runaway. These observations contribute to improving our understanding of upward lightning, which is a primary source of damage to tall structures such as wind turbines and telecommunications towers, as well as aircraft during takeoff and landing. [ABSTRACT FROM AUTHOR]

There are two main beneficial characteristics that doubly salient permanent magnet (PM) electrical machines present for aircraft applications: armature windings and PMs excitation sources placed on the stator side (maintenance and thermal management), and having a clear-cut rotor without PMs or excitation windings (vulnerable at high speeds due to associated centripetal mechanical stresses). Within this framework, a doubly salient permanent magnet (DSPM) generator was conceived by optimizing the stator size and rotor structure to minimize the torque ripple and maximize the root-mean-square (RMS) voltage value per turn of each generator phase. Firstly, a comparison between the 2D and 3D finite element method (FEM) models is made considering the results of 3D finite element analysis (FEA) as our benchmark in order to understand the accuracy of the 2D results against our benchmark model, the 3D one. A multi-objective design strategy based on a 2D FEA is made, it is set to have characteristics closest to optimal for a Boeing 767 turbine, that is, the necessary electromotive force for a required power of 90 kW at 3000 rpm, feeding a simplified Boeing 767 electrical power distribution system. The results show that the machine could not deliver the required power at 3000 rpm since the 2D FEA demonstrates that the 2D model gives optimistic results when compared with the 3D FEM model. However, with a 3D FEA of the machine feeding the aircraft load, it was seen that the machine's efficiency is 92%, suggesting that this machine can be a plausible solution. [ABSTRACT FROM AUTHOR]

Auditory distractions can impair the sensory evaluation of food; however, the specific impact of airplane cabin noise on the sensory perception of in-flight meals remains poorly studied. Here, we investigated the effects of airplane cabin noise on the visual processing of in-flight meal stimuli using electroencephalography (EEG) in twenty healthy male subjects. Resting-state EEG and event-related potential (ERP) responses to in-flight meal images were acquired during quiet and simulated cabin noise conditions. Participants reported mild discomfort and some loss of appetite when exposed to airplane cabin noise. The analysis of resting-state EEG showed an increase in the absolute power of theta and beta frequency bands in the left superior parietal and left frontal/right central regions under simulated cabin noise conditions, compared to quiet conditions. The ERP results showed that the amplitude of responses evoked by visual meal images in the superior parietal area was reduced in the noise condition compared to the quiet condition. Our findings suggest that airplane cabin noise disrupts the visual perception and attentional processing of in-flight food stimuli. These neural changes imply an impact on integrating sensory information, resulting in altered sensory evaluations of food during in-flight dining experiences. [ABSTRACT FROM AUTHOR]

Aircraft engine noise has become a significant concern for air operators to address. Engineering strategies have resulted in the development of easily applicable solutions, known as "passive solutions", that do not necessitate real-time control. These solutions include the incorporation of corrugations or cutouts at critical locations on the engine's aerodynamic surfaces. Realistic solutions, whether approached numerically or tested at small scales, as well as computational models, have been found to closely match experimentally observed behaviors, both in 2D and 3D scenarios. The identified geometries serve as promising starting points for devising combined concepts that may offer even better performance under specific flow conditions. [ABSTRACT FROM AUTHOR]

Exposure to ionizing radiation from galactic cosmic rays (GCR) and solar energetic particles (SEP) at aircraft flight altitudes can have an adverse effect on human health. Although airline crews are classified as radiation workers by the International Commission on Radiological Protection (ICRP), in most countries, their level of exposure is unquantified and undocumented throughout the duration of their career. As such, there is a need to assess pilot ionizing radiation exposure. The Nowcast of Aerospace Ionizing RAdiation System (NAIRAS), a real-time, global, physics-based model is used to assess such exposure. The Automated Radiation Measurements for Aerospace Safety (ARMAS) measurement data set consists of high latitude, high altitude, and long-duration aircraft flights between 2013 and 2023. Here, we characterize radiation exposure at aviation flight altitudes using the NAIRAS model and compare with 45 flight trajectories from the recent ARMAS flight measurement inventory. [ABSTRACT FROM AUTHOR]

Due to the increasing noise pollution, noise control has drawn more and more public attention. Different from traditional methods to reduce noise energy such as active and passive noise control, suppressing noise annoyance through adding sounds is another choice. In previous studies, water sounds are usually used to adjust the annoyance of traffic noise, but the suppression effect of the water sounds varies from person to person. Low-frequency tonal noise is one kind of typical and common mechanical noise, i.e., substation noise, whose annoyance is caused by tonal perception and higher energy in low frequency is difficult to suppress even though adding sounds. In this study, different controllable sounds (water sounds and narrow-band color noises) with different masker-to-noise ratios (MNRs) were added to low-frequency tonal noise to investigate the annoyance suppression effect through listening tests. Furthermore, in order to evaluate the quantitative suppression effect, the standard sample method (SSM) was applied in the listening tests to convert the annoyance difference into the difference of equivalent sound pressure level of 1 kHz and 70 dB pure tone ( Δ S P L 1 k H z , 70 d B ). Results show that different kinds of water sounds and narrow-band color noises effectively reduce noise annoyance. The optimal result comes from adding one kind of water sound, which reduces the annoyance of substation noise by 27.24%, equivalent to reducing Δ S P L 1 k H z , 70 d B by 6.5 dB. Finally, the annoyance prediction model of combined noises is established to choose controllable sounds and predict the suppression effect of annoyance. [ABSTRACT FROM AUTHOR]

Purpose: Aero-engine exhaust plume length can be more than the aircraft length, making it easier to detect and track by infrared seeker. Aim of this study is to analyze the effect of free stream Mach number (M∞) on length of potential core of plume. Also, change in infrared (IR) signature of plume and aircraft surface with variation in elevation angle (θ) is examined. Design/methodology/approach: Convergent divergent (CD) nozzle is located outside the rear fuselage of the aircraft. A two dimensional axisymmetric computational fluid dynamics (CFD) study was carried out to study effect of M∞ on potential core. The CFD data with aircraft and plume was then used for IR signature analysis. The sensor position is changed with respect to aircraft from directly bottom towards frontal section of aircraft. The IR signature is studied in mid wave IR (MWIR) and long wave IR (LWIR) band. Findings: The potential plume core length and width increases as M∞ increases. At higher altitudes, the potential core length increases for a fixed M∞. The plume emits radiation in the MWIR band, whereas the aerodynamically heated aircraft surface emits IR in the LWIR band. The IR signature in the MWIR band continuously decreases as the sensor position changes from directly bottom towards frontal. In the LWIR band the IR signature initially decreases as the sensor moves from the directly bottom to the frontal, as the sensor begins to see the wing leading edges and nose cone, the IR signature in the LWIR band slightly increases. Originality/value: The novelty of this study comes from the data reported on the effect of free stream Mach number on the potential plume core and variation of the overall IR signature of aircraft with change in elevation angle from directly below towards frontal section of aircraft. [ABSTRACT FROM AUTHOR]

This paper aims to verify the effectiveness of a process of superficial protection based on nanotechnologies produced by 4Ward360 and specifically developed for aeronautical applications on composite material aircraft. The Dardo aircraft, a composite VLA category manufactured by CFM Air, was taken as a reference case and two application/investigation areas were identified. The potential anticorrosive behavior of the nanotechnology treatment was investigated when applied to the metal joints of the aircraft, such as the wing–fuselage attachments usually made of Al-2024-T3 aluminum alloy. Furthermore, the potential increased effectiveness in cleaning was investigated as another possible application concerning the parts made of composite material both solid and in a sandwich configuration and the plexiglass parts of the canopy. [ABSTRACT FROM AUTHOR]

Aviation is a vital modern transportation sector connecting millions of passengers globally. Sustainable aviation development holds substantial community benefits, necessitating effective management of its environmental impacts. This paper addresses the need for an accurate and cost-effective aircraft noise monitoring model tailored to non-towered general aviation airports with limited resources for official air traffic data collection. The existing literature highlights a heavy reliance on air traffic data from control facilities in prevailing aircraft noise modeling solutions, revealing a disparity between real-world constraints and optimal practices. Our study presents a validation of a three-stage framework centered on a low-cost transponder unit, employing an innovative experimental and analytical approach to assess the model's accuracy. An economical Automatic Dependent Surveillance-broadcast (ADS-B) receiver is deployed at Purdue University Airport (ICAO Code: KLAF) to estimate aircraft noise levels using the developed approach. Simultaneously, a physical sound meter is positioned at KLAF to capture actual acoustic noise levels, facilitating a direct comparison with the modeled data. Results demonstrate that the developed noise model accurately identifies aircraft noise events with an average error of 4.50 dBA. This suggests the viability of our low-cost noise monitoring approach as an affordable solution for non-towered general aviation airports. In addition, this paper discusses the limitations and recommendations for future research. [ABSTRACT FROM AUTHOR]

The main source of thermal energy is the sun, and with the increase in solar technology, it is now being utilized in many devices such as sun-based panels, photovoltaic cells, batteries and lights, solar fabric, solar water pumping, etc. Nowadays, improvement in flight effectiveness of solar aircraft by utilizing solar energy and nanotechnology is being studied by many scientists. This article is also based on studying the effectiveness of solar aircraft based on solar energy and nanotechnology. For this purpose, few properties of heat transfer among symmetrical wings will be analysed such as porous surface, thermal radiation, convective condition and heat source/sink. It is considered that the ternary hybrid nanofluid moves through the internal side of parabolic trough solar collector. The current study examines the radiative flow of a Carreau tri-hybrid nanoliquid across a convectively heated stretching surface in porous media. Also entropy generation on Carreau fluid is analysed in this work. Energy equation is modelled through heat source/sink and thermal radiation. The well-established numeric technique BVP4c has been used to solve the system of differential equations in the form of concentration, energy and momentum. Several flow variables on fluid velocity, temperature, drag friction, the Nusselt, entropy generation and Bejan number are described in figures and tables. The main outcomes of the current investigation are that the velocity and temperature lowered with augmenting values of Weissenberg number We . Results will prove that THNF is larger in the case of HNF and NF. Further, the drag friction and thermal efficiency of Thnf ( MoS 2 + SiO 2 + Fe 3 O 4 /EG ), Hnf ( MoS 2 + SiO 2 /EG ) and Nf ( MoS 2 /EG ) are computed in percentage with numerous values. The second finding is the addition of entropy due to the increasing magnitude of radiative flow, Carreau fluid variable. When comparing the current results to the reported results, we get a close match. [ABSTRACT FROM AUTHOR]

Acoustic monitoring is necessary in the acoustic assessment of both airports and aircraft, to be able to determine exactly how the acoustic events due to flights affect the quality of life of people living in their vicinity. An assessment of the noise produced by aircraft requires the use of monitoring stations whose location must cover the inhabited area, placed on the active runways of the airport, so that the information obtained can be correlated with the traffic data. The development aims to achieve sound pollution management with real data and a smartphone application that will allow the population to directly access this system. [ABSTRACT FROM AUTHOR]

In this study, a comprehensive evaluation of the potential of dual-polarization and full-polarization L- and S-band airborne SAR (LS-ASAR) data (ISRO's dual-frequency airborne SAR mounted on NASA's Gulfstream III aircraft) in forest above-ground biomass (AGB) estimation has been carried out. The study area comprises the temperate forests of the Lenoir landing site in Southwest Alabama, United States of America. A trunk scattering model based on Vector Radiative Transfer (VRT) theory is used in this study to estimate the AGB. Full-polarization ASAR data inversion retrieves three critical biophysical parameters: tree height, diameter at breast height (DBH), and tree count, whereas with dual-polarization ASAR data, the model is limited to retrieving only two parameters (tree height and DBH). These parameters are then employed in a suitable allometric equation to estimate the AGB over the study area. Validation of the retrieval results is performed through comparison with ground-truth measurements taken from the study site. The findings demonstrate that the inversion of L-band full-polarized data yields the highest correlation (R2 = 0.87, RMSE = 20.37 t/ha), revealing high accuracy in AGB estimation. The L-band dual-polarized data shows a high correlation (R2 = 0.83, RMSE = 30.66 t/ha), indicating reasonable accuracy. However, the S-band data, both full and dual-polarized, reveals weaker correlations with higher RMSE values (R2 = 0.59, RMSE = 55.07 t/ha, and R2 = 0.49, RMSE = 58.31 t/ha, respectively), suggesting a lower degree of reliability. This study emphasizes the pre-eminence of L-band fully polarized data inversion for reliable and accurate AGB estimation while also showing the utility of relatively ubiquitous dual-pol data (L-band) to achieve reasonable accuracy for the same. [ABSTRACT FROM AUTHOR]

This paper presents the results of a listening experiment designed to assess annoyance and perceived loudness (PL) for several unmanned aircraft system (UAS) operations, with the listener simulated in indoor and outdoor positions. This research investigated (i) how participant responses change depending on UAS operation, (ii) which broadband metrics are most suitable for representing annoyance and PL, (iii) differences in noise level required to result in equal participant responses to different operations, and (iv) which sound quality metrics (SQMs) are significant for UAS noise perception. Results indicate annoyance and PL responses were greatest for landing operations with flyovers being the least annoying or loud. LAeq, LASmax, and loudness (N5) were the strongest predictors in representing annoyance. Offset analysis predicted small differences in annoyance responses between flyovers and other operations, but also indicated that flyovers would require an increase to LASmax of 3.3 to 6.3 dB compared to other operations to achieve equal PL. Loudness was the most significant SQM, with minor contributions from impulsivity for annoyance and PL when outside, and tonality for PL when indoors. These findings contribute to the understanding of UAS noise perception for the development of metrics and assessment methods accounting for the characteristics of UAS operations. [ABSTRACT FROM AUTHOR]

Acoustic events exceeding a certain threshold of intensity cannot benefit from a linearization of the governing wave equation, posing an additional burden on the numerical modelling. Weak shock theory associates nonlinearity with the generation of high frequency harmonics that compensate for atmospheric attenuation. Overlooking the persistence of this phenomenon at large distances can lead to mispredictions in gun detection procedures, noise abatement protocols, and auditory risk assessment. The state-of-the-art mostly addresses aircraft jet noise, a stationary and largely random type of signal. The extension of such conclusions to muzzle blasts requires caution in considering their peculiar impulsive and broadband nature. A methodology based on the time and frequency analysis of an experimental dataset of eight calibres intends to find quantitative metrics linked to acoustic nonlinearity in outdoor muzzle blast propagation. Propagating three waveforms (SCAR-L 7.62 mm, Browning 9 mm, and Howitzer 105 mm) up to 300 [m] with the in-house numerical solver based on the nonlinear progressive wave equation, demonstrates that the propagation does not downgrade to truly linear. [ABSTRACT FROM AUTHOR]

Objective: Aircraft noise exposure is linked to cardiovascular disease risk. One understudied candidate pathway is obesity. This study investigates the association between aircraft noise and obesity among female participants in two prospective Nurses’ Health Study (NHS and NHSII) cohorts. Methods: Aircraft day-night average sound levels (DNL) were estimated at participant residential addresses from modeled 1 dB (dB) noise contours above 44 dB for 90 United States (U.S.) airports in 5-year intervals 1995–2010. Biennial surveys (1994–2017) provided information on body mass index (BMI; dichotomized, categorical) and other individual characteristics. Change in BMI from age 18 (BMI18; tertiles) was also calculated. Aircraft noise exposures were dichotomized (45, 55 dB), categorized (

Tests on the content of the electrical component of the electromagnetic field (EMF) were carried out with an NHT3DL broadband meter by Microrad using a 01E (100 kHz ÷ 6.5 GHz) measuring probe. Measurements were made during training flights (Cessna C172, Cessna C152, Aero AT3, and Technam P2006T aircrafts). A neural network was used, the task of which was to learn to predict the successive values of average (ERMS) and instantaneous (EPEAK) electromagnetic fields used here. Such a solution would make it possible to determine the most favorable routes for all aircrafts. This article presents a model of an artificial neural network which aims to predict the intensity of the electrical component of the electromagnetic field. In order to create the developed model, that is, to create a training sequence for the model, a series of measurements was carried out on four types of aircraft (Cessna C172, Cessna C152, Aero AT3, and Technam P2006T). The model was based on long short-term memory (LSTM) layers. The tests carried out showed that the accuracy of the model was higher than that of the reference method. The developed model was able to estimate the electrical component for the vicinity of the routes on which it was trained in order to optimize the exposure of the aircraft to the electrical component of the electromagnetic field. In addition, it allowed for data analysis of the same training flight routes. The reference point for the obtained electric energy results were the normative limits of the electromagnetic field that may affect the crew and passengers during a flight. Monitoring and measuring the electromagnetic field generated by devices is important from an environmental point of view, as well as for the purposes of human body protection and electromagnetic compatibility. In order to improve reliability in general aviation and to adapt to the proposed requirements, aviation training centers are obliged to introduce systems for supervising and analyzing flight parameters. [ABSTRACT FROM AUTHOR]

The request for faster and greener civil aviation is urging the worldwide scientific community and aerospace industry to develop a new generation of supersonic aircraft, which are expected to be environmentally sustainable, and to guarantee a high level of protection for citizens. The availability of novel propulsive technologies, together with the development of new civil supersonic passenger aircraft configurations and missions, is pushing international authorities to update the regulatory framework to limit nuisances on the ground and the contribution to climate change. Existing ICAO noise and emissions standards are outdated as they were developed in the 1970s and tailored to Concorde, the only SST that has ever operated in Western airspace. This article provides (i) a comprehensive review of current environmental regulations for SST, encompassing noise and pollutant emissions near airports (LTO cycle) as well as CO2 emissions and sonic booms, and (ii) updated information about the ongoing rulemaking activities by ICAO, FAA and EASA. This review clearly highlights the following findings: (i) the need to revise current rules to better fit future SST design, operations and technologies; (ii) the need to introduce new regulations to cover additional aspects, including stratospheric water vapour emissions and ozone depletion; and (iii) the need to support regulatory activities with solid technical bases, fostering cooperation with academia, research centres and industry in R&D projects. Eventually, a practical example of how SST rulemaking activities are supported by the collaborative research H2020 MORE&LESS is reported. [ABSTRACT FROM AUTHOR]

This article discusses the possibilities of reducing noise pollution in the vicinity of a selected airport, with an emphasis on practical measures. The proposed procedures, which are routinely employed at commercial airports, would be ineffective or financially unsustainable under the circumstances of the military airports. The objective at military airports is not to maximise capacity, as at civil airports, where the desire to increase capacity is primarily related to profit. The primary objective for military airports is to perform defined tasks, which may include pilot training, search and rescue exercises and combat training. The main measures proposed to reduce noise pollution in the vicinity of the villages are changes in departure and arrival routes, the splitting of night operations into two parts and the introduction of a new article in the AIP and Airport Regulations prohibiting air operations over and in close proximity to the villages nearby. Finally, it is stressed that a significant reduction in noise will only be possible with the support of changes in legislation or above-standard financial investment by the airport operator. [ABSTRACT FROM AUTHOR]

The strong coupling interactions of non-equilibrium flow, microscopic particle collisions and radiative transitions within the shock layer of hypersonic atmospheric re-entry vehicles makes accurate prediction of the aerothermodynamics challenging. Therefore, in this study a self-consistent non-equilibrium flow, collisional--radiative reactions and radiative transfer fully coupled model are established to study the non-equilibrium characteristics of the flow field and radiation of vehicle atmospheric re-entry. The comparison of the present calculation results with flight data of FIRE II and previous results in the literature shows a reasonable agreement. The thermal, chemical and excited energy level non-equilibrium phenomena are obtained and analysed for the different FIRE II trajectory points, which form the critical basis for studying the heat transfer and radiation. The non-equilibrium distribution of excited energy levels significantly exists in the post-shock and near-wall regions due to the rapid vibrational dissociation and electronic under-excitation, as well as the wall catalytic reactions. The analysis of stagnation-point heating of FIRE II illustrates that the translational--rotational convection and the dissociation component diffusion play key roles in the aerodynamic heating of the wall region. The spectrally resolved radiative intensity in the entire flow field indicates that the vacuum ultraviolet radiation caused by the high-energy nitrogen atomic spectral lines makes the main contribution to the radiative transfer. Finally, it is found that the non-equilibrium flow--radiation coupling effect can exacerbate the excited energy level non-equilibrium, and further affect the gas radiative properties and radiative transfer. This fully coupled study provides an effective method for reasonable prediction of atmospheric re-entry flow and radiation fields. [ABSTRACT FROM AUTHOR]

The adoption of hybrid–electric propulsion, allowing us to partially replace fuel with batteries and to reduce aircraft in-flight emissions, represents one of the main investigated solutions to mitigate the aviation climate impact. Despite its environmental potential being appealing for a practical application, two main drawbacks limit the actual implementation of this technology: first, the low gravimetric energy density of the batteries restricts hybrid–electric aircraft payload and range capabilities; second, the production of electricity is currently not entirely based on renewable energy sources, hence a non-direct emissions budget may limit the benefit in terms of overall decarbonization. When designing hybrid–electric aircraft, even projecting its actual entry into service in the next decades, it is necessary to take these limitations into account depending on both the more reliable technological forecasts on the development of electric components and on the estimates of electricity production. A proper analysis of the figure of merits related to the operation of such an aircraft, therefore, becomes crucial in assessing the impact related to its introduction into service. In this context, trade-offs between different performance metrics may be needed to efficiently exploit the environmental benefits of such an advanced concept, while limiting the possible drawbacks coming from its utilisation. This paper provides a performance analysis of hybrid–electric aircraft through an assessment of the relevant figures of merit characterizing its operations. In particular, direct and non-direct emissions, climate impact, ground pollution, operating costs, fuel consumption, weight, and a combination of these figures of merit allow us to define a proper development perimeter in which a possible (future) hybrid–electric aircraft can express its maximum potential towards all the aspects of its utilisation. The trade-off analyses provided in this paper allow us to identify more effective paths for the actual development of hybrid–electric aircraft, highlighting the impact of the selected design variables on the performance metrics, and bringing to light also the possible related limitations. [ABSTRACT FROM AUTHOR]

Computational models are used to predict the performance of human listeners for carefully specified signal and noise conditions. However, there may be substantial discrepancies between the conditions under which listeners are tested and those used for model predictions. Thus, models may predict better performance than exhibited by the listeners, or they may "fail" to capture the ability of the listener to respond to subtle stimulus conditions. This study tested a computational model devised to predict a listener's ability to detect an aircraft in various soundscapes. The model and listeners processed the same sound recordings under carefully specified testing conditions. Details of signal and masker calibration were carefully matched, and the model was tested using the same adaptive tracking paradigm. Perhaps most importantly, the behavioral results were not available to the modeler before the model predictions were presented. Recordings from three different aircraft were used as the target signals. Maskers were derived from recordings obtained at nine locations ranging from very quiet rural environments to suburban and urban settings. Overall, with a few exceptions, model predictions matched the performance of the listeners very well. Discussion focuses on those differences and possible reasons for their occurrence. [ABSTRACT FROM AUTHOR]

Seattle-Tacoma International Airport (SEA), Washington, installed an educational display to raise passengers' knowledge and awareness of wildlife trafficking. Little is known about the efficacy of wildlife trafficking-related educational displays at airports. In the fall of 2022, Port of Seattle (PoS) Business Intelligence conducted an evaluation to assess the impact of the display. The evaluation included three components: observation of passengers viewing the display; a survey with passengers who viewed the display; and a survey with passengers who did not view the display. Observations revealed that 0.8 per cent of passengers stopped to view the display. Mean viewing time was 48 seconds. The more passengers passed through the concourse, the fewer stopped at the display. Most non-viewers (88 per cent) did not notice the display as they passed it on the way to their gate. Non-viewers who noticed the display but did not stop to view it gave being in a hurry and wanting to get to their gate as primary reasons for not stopping. Viewers of the display, compared to non-viewers, reported a greater level of confidence that they could spot a product made from endangered wildlife, increased knowledge about actions that can contribute to wildlife trafficking and a greater belief that their actions can help save endangered animals. Although the display did have an impact on viewers, fewer than 1 per cent of passengers who passed by the display viewed it. Most passengers did not notice it. The findings of this evaluation raise the issue of whether passengers on the way to their departure gate are receptive to viewing an educational display. There may be more opportune approaches to educate passengers about wildlife trafficking, such as presenting information about wildlife trafficking on television screens in gate areas or as part of in-flight entertainment. [ABSTRACT FROM AUTHOR]

This paper presents the technological advancement of using friction powders to increase the absorption of acoustic liners used in the reduction of tonal noise generated by aero-engines or for other applications related to Helmholtz resonators used in noise absorption of low frequencies. The experimental research was conducted during the European project ARTEM (2017–2022), and after. This concept was inspired by the discovery made by several historians of narrow neck bottles filled with ash in the old Christian churches. These artifacts were made with the purpose of absorbing low frequency noises. Based on this creative idea, the present authors proposed a new method of noise absorption capabilities of acoustic liners filled with various types and quantities of natural and artificial powders. Considering the positive results the ARTEM project offered, COMOTI continued testing this concept by using even finer cork powders manufactured with a new technology. Measurements in Kundt tubes showed that noise absorption increased significantly in broadband for low frequencies (over 0.9 at high frequencies and 0.6 at low frequencies, 500 Hz). Some of the researched powders can be used in the field of bladed machines to reduce the aerodynamic noise of an aircraft or in the automotive industry where the reduction of low frequency noises is necessary. [ABSTRACT FROM AUTHOR]

The excessive noise present within an aircraft cabin during flight operations constitutes a notable origin of fatigue, stress, and communication impediments for both pilots and passengers. Ensuring the comfort, well-being, and safety of passengers and crew members necessitates the accurate anticipation of noise levels. This study concerns the computation of structure-borne noise levels within the cabin of a tiltrotor aircraft. This investigation employed two distinct methodologies: advanced transfer path analysis (ATPA) and statistical energy analysis (SEA). To assess the results obtained with the ATPA approach, the acquired outcomes were compared with empirically measured sound pressure levels during airplane mode operations. The contributions of air-borne and structure-borne noises were calculated with the ATPA methodology. On the other hand, the structure-borne noise was calculated with a hybrid experimental–SEA model with ACTRAN software, and its results were compared with those of the ATPA method. The results show a good agreement between these methods at high frequencies, while at low frequencies, certain adjustments or modifications to the SEA model are necessary to predict the noise levels. [ABSTRACT FROM AUTHOR]

Aircraft are exposed to cosmic radiation depending on their flight altitude and latitude. Therefore, flight attendants are exposed to radiation for long periods. In this study, a 0.3 mm thick fabric was designed with which to manufacture crew clothes to shield them against external exposure to space radiation, and the shielding performance was analyzed based on empirical experiments in a real environment. Gadolinium oxide, which has a high neutron reaction cross-section, and tungsten, which is useful for gamma-ray shielding, were proposed as the main raw materials for the shielding fabric, and the shielding performance was evaluated using detectors on Arctic flight routes. Composite (KG-01) and single (KG-02) shielding materials were used. In the case of KG-01, the transmission dose rate was 90.7 ± 5.6% compared with the unshielded case, showing an average space-radiation dose reduction of 9.3%. With KG-02, the transmission dose rate was 103.1 ± 2.0% compared with the unshielded case, and the average dose rate increased by 3.1%; therefore, there was no shielding effect against space radiation. Considering the statistical error of the environmental radiation at aircraft flight altitudes, KG-01 had a shielding effect of at least 5%; however, KG-02 yielded no significant shielding effects. [ABSTRACT FROM AUTHOR]