Aircraft Altitude Research Articles

A high‐altitude thermal infrared method for estimating moose abundance and demography in Rocky Mountain National Park, USA

Resource managers require accurate estimates of large herbivore abundance and demography to maintain ecological integrity. Common methods to count these species, including observations from low altitude helicopter flights, may conflict with other protected area management objectives and struggle to produce precise estimates for more cryptic species. To address these issues, we evaluated thermal infrared (TIR) assisted counts of Shiras moose Alces alces shirasi in a temperate montane ecosystem of Colorado, USA. We binned the 694.7 km2 study area into two strata, depicting higher and lower moose habitat suitability. Sixty transects (each 536 m wide by 5 km long) were randomly selected and flown from fixed wing aircraft flying at altitudes centered around ~ 610 m (2000 ft) above ground level (AGL) in July 2019 and again in July 2020. We determined abundance and demographic information using double‐observer line distance sampling with estimates produced using n‐mixture models. Detection probability of groups on the line, and of individuals within a group, conditional on the group being observed, were high. Mean moose density estimates across the study area were consistent from year to year, with reasonable confidence. We estimated 0.215 moose km‐2 (HDI 0.145, 0.286) in 2019 and 0.207 moose km‐2 (HDI 0.144, 0.276) in 2020. Within‐stratum estimates varied from year to year, likely an effect of the definition of suitable habitat and transect classifcation. Estimated ratios of bulls per cow and calves per cow fell within expected ranges for Shiras moose in Colorado but did vary across years. Thermal clutter created some impacts to TIR video quality. Our study indicates that this approach can reliably estimate moose densities in forested and topographically complex environments, while maintaining greater aircraft altitude above ground level when compared with traditional aerial survey methods. This reduced disturbance to wildlife, impacts to wilderness and improved aviator and aircraft passenger safety.

Enhanced Air Traffic Control Safety Using low Earth orbit Satellites: Non-TCAS Aircraft

This paper presents a study on a novel TCAS design that combines the exploitation of low-orbit satellites with the existing TCAS system to improve operational efficiency and overcome challenges. With the continuous growth of air traffic, ensuring safety remains a top priority. TCAS was developed to mitigate the risks of aircraft collisions and is mandatory on large transport aircraft. TCAS uses information and data to determine the altitude and relative positions of nearby aircraft. However, despite the advances in air traffic control (ATC) systems, non-TCAS-equipped aircraft continue to operate in the airspace, potentially increasing the risk of mid-air collisions. In addition, existing TCAS systems often generate frequent and unnecessary alarms, especially in densely populated terminal areas, leading to erroneous pilot actions. The proposed solution aims to detect non-TCAS-equipped aircraft by other aircraft, whether they are equipped with TCAS or not. Therefore, the goal is to optimize the efficiency of TCAS to reduce the risk of mid-air collision and improve overall aviation safety. The management applications are distributed on the cloud to save resource exploitation, including energy consumption by processing and air traffic control-related exchanges.

Design and simulation of aircraft altitude control based on RBFPID controller

Design and simulation of aircraft altitude control based on RBFPID controller

АНАЛІЗ ВПЛИВУ КУТА СТРІЛОПОДІБНОСТІ НА ХАРАКТЕРИСТИКИ СТАТИЧНОЇ АЕРОПРУЖНОСТІ КРИЛА НАВЧАЛЬНО-ТРЕНУВАЛЬНОГО ЛІТАКА

The article is dedicated to the analysis of static aeroelastic phenomena in the wing of a trainer aircraft and the general influence of wing sweep on critical speeds. Aeroelasticity studies the interaction between aerodynamic and elastic forces and the impact of this interaction on the aircraft's structure. There are two types of aeroelasticity: static and dynamic. The article reviews and analyzes publications related to this issue. The analysis of the research shows that when designing an aircraft, it is necessary to determine the aeroelastic characteristics of its aerodynamic surfaces. In addition to structural rigidity, the sweep angle also influences these phenomena. The scientific novelty of the study lies in the fact that, unlike the analyzed research, the designed wing structure of a trainer aircraft is considered.For the designed trainer aircraft, the critical speeds of static aeroelastic phenomena were determined. The calculation of the influence of the wing sweep angle on the divergence speeds of the trainer aircraft confirms previously obtained results regarding this influence. When the sweep is increased or decreased for wings with the same span, the torsional rigidity of the wing decreases due to the increase in the length of the line of centers of rigidity. However, the most significant impact on the aeroelastic characteristics is made by the shift of the bending center when the sweep angle changes.With forward sweep, the arm of the aerodynamic forces relative to the bending center increases, thereby reducing the critical divergence speeds. For straight sweep, as the sweep increases, the bending center moves forward, and at a certain point, the bending center is located in front of the aerodynamic center. This means that the wing twist angle decreases as the aerodynamic force increases, which, in the considered planar case, eliminates the occurrence of divergence.The preliminarily determined maximum flight speed does not exceed the critical speeds of divergence and aileron reversal. This result represents the practical value of the study. To achieve higher flight speeds, wings with straight sweep should be used. More precise computational or experimental methods for determining aeroelastic characteristics should be used in the subsequent design stages to prevent aeroelastic phenomena across the entire operational range of speeds and altitudes of the trainer aircraft.

The consideration of a simplified method for predicting aircraft noise

The Japanese segment model focuses on understanding noise impacts in the surrounding areas relatively close to the airport. The basic data to be prepared for predicting are usually the results of measurements and analysis in the area near the airport. In areas farther away from airports, the altitude of aircraft is higher, there is an issue that prediction results based on the basic data collected near airports accurately reflect the reality. Often, areas far from airports get complaints even if noise exposure was not high. There is a desire for a model that can predict with relatively high accuracy and ease even in locations far from airports like this. Based on this background, we have developed a simple prediction model based on actual observation results of noise and flight paths, which can be used as basic data for aircraft noise prediction. In this approach, a database is created using noise measurements obtained from unattended noise monitoring and short-term survey results and aircraft position information from the ADSB. In noise propagation calculations, predictions are made considering factors such as lateral attenuation of ground surfaces, air absorption, and variability in flight paths by a simple method.

Operational Noise Abatement Through Control of Climb Profile on Departure

This work introduces a noise abatement procedure for reducing aircraft community noise during departures based on the control of climb profiles via procedural level-offs. The proposed procedure consists of enforcing an altitude restriction along a departure path such that aircraft maintain level flight when overflying strategically selected regions. During this level segment, thrust demand is lower than during climbing flight, which results in lower engine noise. However, this effect must be balanced with the lower aircraft altitude in the level segment, which may reduce the distance between aircraft and observers. Thus, a systematic analysis methodology is needed to design an effective noise abatement procedure based on this technique, which has been developed and is presented in this paper. Modeling results show potential undertrack peak A-weighted noise level reductions of 2–4 decibels for both narrowbody and widebody aircraft in the level-off area depending on the level-off altitude and an associated increase of 1.5–6 decibels in the region where the climb is resumed. An example application of this procedure is demonstrated at Boston Logan Airport, with cumulative changes in noise impacts being assessed for one full day of operations. In this example application, fuel burn penalties are estimated at 37 pounds for a representative narrowbody operation and 142 pounds for a representative widebody operation.

Evidence of a New Population of Weak Terrestrial Gamma‐Ray Flashes Observed From Aircraft Altitude

AbstractTerrestrial Gamma‐ray Flashes (TGFs) are ten‐to‐hundreds of microsecond bursts of gamma‐rays produced when electrons in strong electric fields in thunderclouds are accelerated to relativistic energies. Space instruments have observed TGFs with source photon brightness down to ∼1017–1016. Based on space and aircraft observations, TGFs have been considered rare phenomena produced in association with very few lightning discharges. Space observations associated with lightning ground observations in the radio band have indicated that there exists a population of dimmer TGFs. Here we show observations of TGFs from aircraft altitude that were not detected by a space instrument viewing the same area. The TGFs were found through Monte Carlo modeling to be associated with 1015–1012 photons at source, which is several orders of magnitude below what can be seen from space. Our results suggest that there exists a significant population of TGFs that are too weak to be observed from space.

A method to mitigate cyber exploits on automatic dependent surveillance-broadcast (ADS-B) data transmissions

PurposeAutomatic dependent surveillance-broadcast (ADS-B) is the foundational technology of the next generation air transportation system defined by Federal Aviation Authority and is one of the most precise ways for tracking aircraft position. ADS-B is intended to provide greater situational awareness to the pilots by displaying the traffic information like aircraft ID, altitude, speed and other critical parameters on the Cockpit Display of Traffic Information displays in the cockpit. Unfortunately, due to the initial proposed nature of ADS-B protocol, it is neither encrypted nor has any other innate security mechanisms, which makes it an easy target for malicious attacks. The system is vulnerable to various active and passive attacks like message ingestion, message deletion, eavesdropping, jamming, etc., which has become an area of concern for the aviation industry. The purpose of this study is to propose a method based on modified advanced encryption standard (AES) algorithm to secure the ADS=B messages and increase the integrity of ADS-B data transmissions.Design/methodology/approachThough there are various cryptographic and non-cryptographic methods proposed to secure ADS-B data transmissions, it is evident that most of these systems have limitations in terms of cost, implementation or feasibility. The new proposed method implements AES encryption techniques on the ADS-B data on the sender side and correlated decryption mechanism at the receiver end. The system is designed based on the flight schedule data available from any flight planning systems and implementing the AES algorithm on the ADS-B data from each aircraft in the flight schedule.FindingsThe suitable hardware was developed using Raspberry pi, ESP32 and Ra-02. Several runs were done to verify the original message, transmitted data and received data. During transmission, encryption algorithm was being developed, which has got very high secured transmission, and during the reception, the data was secured. Field test was conducted to validate the transmission and quality. Several trials were done to validate the transmission process. The authors have successfully shown that the ADS-B data can be encrypted using AES algorithm. The authors are successful in transmitting and receiving the ADS-B data packet using the discussed hardware and software methodology. One major advantage of using the proposed solution is that the information received is encrypted, and the receiver ADS-B system can decrypt the messages on the receiving end. This clearly proves that when the data is received by an unknown receiver, the messages cannot be decrypted, as the receiver is not capable of decrypting the AES-authenticated messages transmitted by the authenticated source. Also, AES encryption is highly unlikely to be decrypted if the encryption key and the associated decryption key are not known.Research limitations/implicationsImplementation of the developed solution in actual onboard avionics systems is not within the scope of this research. Hence, assessing in the real-time distances is not covered.Social implicationsThe authors propose to extend this as a software solution to the onboard avionics systems by considering the required architectural changes. This solution can also bring in positive results for unmanned air vehicles in addition to the commercial aircrafts. Enhancement of security to the key operational and navigation data elements is going to be invaluable for future air traffic management and saving lives of people.Originality/valueThe proposed solution has been practically implemented by developing the hardware and software as part of this research. This has been clearly brought out in the paper. The implementation has been tested using the actual ADS-B data/messages received from using the ADS-B receiver. The solution works perfectly, and this brings immense value to the aircraft-to-aircraft and aircraft-to-ground communications, specifically while using ADS-B data for communicating the position information. With the proposed architecture and minor software updates to the onboard avionics, this solution can enhance safety of flights.

Balancing predictability and flexibility through operation volume-constrained visual flight rule operations in low altitude airspaces

The advancement in uncrewed aircraft systems such as small drones and advanced air mobility vehicles such as Electric Vertical Take Off and Landing aircraft (eVTOL) has called for airspace integration at low altitudes of both traditional aircraft, such as helicopters and new entrants, such as drones and eVTOL. Currently, the trajectories and necessary buffers around them of flights operating under visual flight rules are not possible to predict. This research proposes the use of flight mission characteristics to model the trajectory and evaluates temporal, lateral and vertical deviations to define the safety buffers which can be used to generate operation volumes, geo-fencing such low-altitude flights and separating them from other traffic in a safe and efficient manner. Real flight test data obtained for the purposes of this study and pilots’ interviews assure high fidelity and practicability of the proposal.

Analysis of aerodynamic characteristics of aircraft during take-off and landing

Take-off and landing are the most critical phases of flight, as they require the pilot's utmost attention and skill. Through force analysis, we can determine the main factors that affect aircraft take-off and landing performance. By understanding these factors, we can improve the safety and efficiency of air travel. During take-off and landing, lift, weight, thrust, and drag work together to give rise to the aircraft's resultant motion and angle of attack. By analysing these forces, we can determine the aircraft's speed and altitude during these critical phases. Ground friction is a factor that is often neglected in theoretical analysis but has a significant effect on aircraft performance in reality. Friction between the wheels and the runway affects the braking of the aircraft after it begins to decelerate on the runway, making it essential for a secure landing. Accurately measuring the friction coefficient can help prevent accidents, particularly in severe weather conditions. Investigating these factors can aid in improving aircraft performance, achieving better energy efficiency, and meeting modern society's needs for safe and efficient air travel. By considering these factors, we can enhance the safety and efficiency of aircraft take-off and landing, ensuring a more reliable and enjoyable travel experience for all.

Evaluation of effective dose for gamma-rays of terrestrial gamma-ray flashes in aviation: spectral- and atmosphere-effects

Terrestrial Gamma-ray Flashes (TGFs) are intense and fast gamma-ray emissions, energy up to 100 MeV, generated within the Earth's atmosphere at altitudes below 20 km. Satellite observations indicate the TGFs are not a rare phenomenon, being produced on average at one per thunderstorm, yielding a global production rate of ≈35 TGFs/min within a latitude band of ±38°. Furthermore, the TGFs may coincide with the flight altitudes for several commercial aircraft routes, typically within the 10−14 km range, and thus cause passengers/crews unexpected exposure to large fluxes of high-energy ionizing radiation, namely for distances of the order of km.Herein, we introduce a novel approach based on a simple analytic/numeric methodology to estimate the TGFs gamma-ray emissions effective doses based on the differential fluence of photons at aircraft altitude and tabulated effective dose conversion coefficients versus the photon energy. For the first time, we examine the effective dose dependence on TGF's gamma-ray energy spectrum models found in literature and the atmosphere mass thickness crossed by the gamma-rays. Additionally, since the real irradiation geometry of the whole body in aircraft might be a combination of the several idealized geometries used in radiation protection, we considered beyond the typical anteroposterior (AP), the posteroanterior (PA), and the rotational (ROT) geometries as representative irradiation geometries in exposure to TGF gamma-ray's emissions.We calculated the effective dose versus the distance between the TGF site and the aircraft altitude (12.5 km) within the 0.1−5.0 km range and atmosphere mass thickness within the 3.3−213 g cm−2 range. Additionally, we calculated the average effective dose per fluence versus the atmosphere mass thickness crossed by the gamma-rays. At a distance of 1 km (34 g cm−2) and for the typical exponential cut-off power-law model (α = 1, EC = 7.3 MeV), the effective dose was within the 0.18−0.19 mSv range, being the respective average effective dose per fluence within the 10.8−11.6 pSv cm2 range. Moreover, for the variant of the exponential cut-off power-law model (α = 1, EC = 7.3 MeV, Emin = 1 MeV), the effective dose was within the 0.42−0.46 mSv range, being the respective average effective dose per fluence at 34 g cm−2 within the 12.7−13.6 pSv cm2 range.Generally, the data obtained agree with the scarce data found in the literature for similar conditions, evidencing the effect of the parameterization of the TGFs gamma-rays energy models, which may result in a 2- to 10-fold effective dose escalation. For the typical exponential cut-off power-law model (α = 1, EC = 7.3 MeV), the data obtained for an aircraft that passes through the vicinity of one TGF, with a distance of 1 km, points to an increase of the aircraft crew and passengers' doses of few tenths mSv over the cosmic radiation dose of few tens μSv along a typical flight of 6 h duration, representing ≈20% and ≈1% of the ICRP-2007 annual reference levels for passengers (1 mSv) and aircraft crew (20 mSv), respectively. More, with a distance of 0.5 km, the effective dose value is comparable with the annual dose for the aircraft crew due to the cosmic radiation for a typical yearly flight time of 500 h, representing ≈130% and ≈7% of the ICRP-2007 annual reference levels for passengers and aircraft crew, respectively.

Practical examples for the flight data compatibility check

Accurate information about aircraft speed, altitude, and aerodynamic flow angles is essential for evaluating aircraft performance and handling qualities. These quantities are determined from air data measurements taken by sensors normally located near the aircraft cockpit. Since these sensors are affected by the distorted flow field around the fuselage, a correction must be applied. Before the first flight, a set of calibration parameters is usually determined from wind tunnel experiments or CFD calculations. However, the Data Compatibility Check (DCC) method allows a more accurate air data sensor calibration during the certification flight test. This method reconstructs air data quantities from inertial acceleration, angular rate measurements and the flight path. By comparing the reconstructed quantities with the measured ones, the structure and parameters of air data sensor models can be identified. In this paper, an introduction to the data compatibility check method and the setup used in a flight test for system identification is given. The DCC is applied on data gathered from a test campaign with the new DLR research aircraft Dassault Falcon 2000LX ISTAR. Use cases for the calibration of the nose boom airflow vanes and the correction of sensors during large sideslip maneuvers will be presented in this paper.

Helicopter radio system for low altitudes and flight speed measuring with pulsed ultra-wideband stochastic sounding signals and artificial intelligence elements

The subject matter of this study is algorithms for measuring the components of an aircraft speed vector and altitude. The goal of this study is to improve algorithms for processing wideband stochastic pulse signals in helicopter low-altitude and flight-speed radio systems by introducing secondary signal processing based on artificial intelligence elements. The tasks to be solved are as follows: to develop an optimal algorithm for determining the speed and altitude of flight for a helicopter radio complex; to supplement the signal processing algorithm with an artificial intelligence-based processor to determine the "safety" of the current trajectory; provide the pilot with relevant information about possible options for further actions based on an analysis of the current position of the helicopter and flight parameters; and to analyse the efficiency of the proposed complex when using various artificial intelligence-based algorithms. The methods used are as follows: methods of mathematical statistics and optimal solutions for solving problems of statistical synthesis of active radio complex structure; methods of machine learning; and methods of computer simulation. The following results were obtained. The algorithms for signal processing in a helicopter radio complex are obtained by the method of maximum likelihood, and the use of three radio channels to calculate the full vector of speed and altitude is argued. The structure of a secondary information processing system, using algorithms based on artificial intelligence is proposed. The effectiveness of determining the safety of the current landing trajectory using various algorithms based on artificial intelligence (LinearSVC, GaussianNB, DecisionTreeClassifier, RandomForestClassifier, KNeighborsClassifier, MLPClassifier and RidgeClassifier) was analysed. Conclusions. The simulation results show that in the presence of accurate (noise-free) information on the current location of the helicopter, its axial velocities, and a map of the terrain with defined areas dangerous for landing, the DecisionTreeClassifier and RandomForestClassifier algorithms can provide a high probability of correctly determining the safety of the current landing trajectory. At the same time, in the presence of instability in the measurements of helicopter movement parameters, only the RandomForestClassifier algorithm maintains high accuracy.

The effect of the eruption of mount Hunga-Tonga on density altitude, air pressure and flight operations in eastern Indonesian

There was an eruption of the Hunga Tonga volcano in the Pacific Ocean on January 15, 2022 and produced the phenomenon of Shock Waves in the atmosphere, in addition to sonic booms, and tsunami waves that spread to various parts of the world. Data from the automated weather observing system (AWOS) in several Airports in Indonesia were analyzed to assess the impact of the eruption of Mount Tonga on the Indonesian atmosphere. There are sudden changes in air pressure (QNH) at locations (Airports) including Sorong, Wamena, Ternate, Sumbawa, Biak, Geser, Lombok, Sabu, and Kupang, with a range between 0.6 to 1.9 Mb. These atmospheric waves propagate at a speed of about 1248 km/hour. This drastic change in air pressure is not followed by a significant change in density altitude which affects the effectiveness of the aircraft’s lift, but a sudden change will cause a change in air pressure (QNH) in the altimeter which can cause a change in aircraft altitude. This sudden change has high probability to result in a plane crash due to a stall or undershoot or collision with aircraft.

Flight Test Investigation on Loss of Control Due to Flap and Landing Gear Configuration Change

Extension of flaps during landing and take-offs not only increases the lift produced by the wing due to change in camber of the aerofoil but also increases the wing downwash which reduces the angle of attack on the horizontal tail and reduces the tail efficiency resulted in to significant change in pitch attitude, aircraft altitude and airspeed. Lowering of landing gear increases the interference drag and lead to vortex shedding which reduces the pressure underneath the wing, as a result aircraft have pitching down moment. During this phase pilot is pre-occupied and might be distracted and if requisite control input is not provided by the pilot to maintain required aircraft attitude it can lead to uncontrollable flight condition and loss of control in flight. To investigate these effects, Flight tests were carried out on Hansa-3 and Cessna-206H aircraft at IIT Kanpur along with Pilot and on Cirrus Jet SF-50 in X-Plane 11 Flight Simulator. During flight test aircraft exhibited significant change in pitch attitude, roll angle, aircraft altitude and airspeed and aircraft even stalled. Extension of flaps with 30° bank along with extended landing gear has given more stability to the aircraft and increase in pitch attitude and altitude was less in comparison of retracted Landing Gear.

Linking digital image intensity to carrier density in low-pressure corona discharges

The electrification of transportation, and aircraft electrification in particular, is experiencing rapid development due to the more efficient use of energy. Since the dielectric strength of air decreases at the cruising altitudes of commercial aircraft due to the reduced pressure environment, there is a need to control and minimize the risks associated with electrical discharges. This paper shows from experimental and computational data that there is a relationship between the electrical and optical phenomena involved in the discharge process. To this end, this paper analyzes corona discharges generated using different electrode geometries under a wide range of pressures from 100 kPa to 10 kPa. It is shown that the densities of charged particles or charge carriers generated during the discharge process are positively correlated with the intensity of corona images acquired with a digital imaging sensor sensitive to the near UV and visible wavelength ranges. Therefore, the intensity of the images can be used as a reliable and accurate indicator of the corona activity, the values of which are related to the ionization processes involved in the discharges. The results presented in this paper can be applied in various physical and engineering fields, such as high voltage engineering, power line monitoring, or ozone generation, among others.

Literature Review on Air Conditioning Heat load Analysis of a Cabin

Abstract: Air conditioning system is necessary in automobile to maintain the comfort condition. Therefore, it is important to study transient response of vehicle under real driving conditions. The Heat Balance Method (HBM) is used for estimating the heating and cooling loads which develops inside the vehicle cabin. The Load Calculation of Automobile Air Conditioning System is calculated and presented. An hourly cooling load is calculated in Tirunelveli region with respect to its latitude. Tons of refrigeration required is also found out from the cooling load calculation and a review on cooling load calculation is also presented. This study gives overall cooling load and AC power consumption which can be used by HVAC engineers to design more efficient car AC systems. Only by knowing the cooling load and source of thermal load, we can develop intelligent system to reduce AC consumption. Environmental Control System (ECS) is a generic term used in aircraft industry for maintaining the required air temperature and pressure inside passenger and crew compartment. The real challenge for an ECS is to operate and supply adequate cooling over a wide range of ground and flight conditions in a most reliable and efficient manner. The most important aspect of ECS is to know the cabin heat loads during air cooling or air heating phases. A precise calculation of aircraft heat load would be a long process requiring detailed knowledge of the aircraft structure and of the quantities involved in the mechanism of heat pick up and interchange in the cabin. This paper describes a method that may be applied in calculating the heat load for any aircraft and calculations are shown for a typical light transport aircraft under the conditions that, the cabin altitude is maintained within 0 ft to 8000 ft (2438.4m) for the aircraft altitude of 0 ft to 25000ft (7620m). The system shall be capable of maintaining temperatures within 59°F to 75°F (15°C to 30°C).

Conflict resolution in the case of convective weather cell circumvention

This research analyzes the area required for the conflict resolution between aircraft in two flows impacted by a convective weather cell (CWC). The CWC is introduced as a constrained area, forbidden to flight through, which affects the air traffic flows. Prior the conflict resolution, two flows and their intersection are relocated away from the CWC area (thus enabling circumvention of the CWC), which is followed by a tuning of the relocated flows intersection angle in order to create the minimal size of the conflict zone (CZ—a circular area centered at the intersection of two flows, which provides aircraft enough space to completely resolve the conflict within). Therefore, the essence of the proposed solution is in providing conflict free trajectories for the aircraft in intersecting flows that are affected by the CWC, with the goal of minimizing the CZ size, so the finite occupied airspace for the conflict resolution and the CWC circumvention could be reduced. Compared to the best solutions and current industry practice, this article is focused in reduction of the airspace required for aircraft to aircraft and aircraft to weather conflict resolution, and not to distance travelled, time savings, and fuel consumption minimization. The conducted analysis in the MicrosoftExcel2010 confirmed the relevance of the proposed model and demonstrated variations in efficiency of the utilized airspace. The proposed model's transdisciplinary nature makes it potentially applicable in other fields of study, such as the conflict resolution between unmanned aerial vehicles (UAVs) and fixed objects like buildings. Building on this model and taking in consideration large and complex data sets, such as weather related data and flight data (aircraft position, speed, and altitude), we believe it is possible to conduct more sophisticated analyses that would take advantage of Big Data.

Potential impact of offshore human activities on gray whales (Eschrichtius robustus)

Gray whale (Eschrichtius robustus) reactions to offshore human activities have been relatively well studied compared to those of other mysticetes. Studies of short-term behavioural responses to underwater noise associated with aircraft, ships and seismic explorations indicate a 0.5 probability that whales will respond to continuous broadband noise when sound levels exceed ca 120dB2 and to intermittent noise when levels exceed ca 170dB, usually by changing their swimming course to avoid the source. Gray whales were ‘startled’ at the sudden onset of noise during playback studies, but demonstrated a flexibility in swimming and calling behaviour that may allow them to circumvent increased noise levels. Whales may be ‘harassed’ by noise from large commercial vessels, especially in shipping lanes or near busy ports. Gray whales sometimes change course and alter their swimming speed and respiratory patterns when followed by whalewatching boats. Conversely, some whales swim toward small skiffs deployed from whalewatching boats in breeding lagoons, seemingly attracted by the noise of idling outboard engines. Reported gray whale reactions to aircraft are varied and seem related to ongoing whale behaviour and aircraft altitude. Whale response to research involving tagging and biopsy sampling appears to be short term. Gray whales were seen swimming through surface oil from the Exxon Valdez oil spill along the Alaskan coast and showed only partial avoidance to natural oil seeps off the California coast. Laboratory tests suggest that gray whale baleen, and possibly skin, may be resistant to damage by oil, but spilled oil or oil dispersant in a primary feeding area could negatively affect gray whales by contaminating benthic prey. Gray whales are sometimes injured or killed in collisions with vessels or entanglement in fishing gear. Concern about the cumulative long-term impact of offshore human activities is particularly acute in the Southern California Bight, where many activities are often concurrent.

Adaptive mechanisms of Bacillus to near space extreme environments

Earth's near space is an extreme atmosphere environment with high levels of radiation, low atmospheric pressure and dramatic temperature fluctuations. The region is above the flight altitude of aircraft but below the orbit of satellites, which has special and Mars-like conditions for investigating the survival and evolution of life. Technical limitations including flight devices, payloads and technologies/methodologies hinder microbiological research in near space. In this study, we investigated microbial survival and adaptive strategies in near space using a scientific balloon fight mission and multi-omics analyses. Methods for sample preparation, storage, protector and vessel were optimized to prepare the exposed microbial samples. After 3 h 17 min of exposure at a float altitude of ~32 km, only Bacillus strains were alive with survival efficiencies of 0–10−6. Diverse mutants with significantly altered metabolites were generated, firstly proving that Earth's near space could be used as a new powerful microbial breeding platform. Multi-omics analyses of mutants revealed cascade changes at the genome, transcriptome and proteome levels. In response to environmental stresses, two mutants had similar proteome changes caused by different genomic mutations and mRNA expression levels. Metabolic network analysis combined with proteins' expression levels revealed that metabolic fluxes of EMP, PPP and purine synthesis-related pathways were significantly altered to increase/decrease inosine production. Further analysis showed that proteins related to translation, molecular chaperones, cell wall/membrane, sporulation, DNA replication/repair and anti-oxidation were significantly upregulated, enabling cells to efficiently repair DNA/protein damages and improve viability against environmental stress. Overall, these results revealed genetic and metabolic responses of Bacillus to the harsh conditions in near space, providing a research basis for bacterial adaptive mechanisms in extreme environments.