Aviation System Research Articles

Identification of Failure Modes in the Collision Avoidance System of an Autonomous Ferry using Adaptive Stress Testing

As complex autonomous systems emerge in the maritime sector, measures must be taken in order to ensure thorough safety assessment. Real-world testing can be costly and potentially dangerous, and therefore there is a need for suitable simulation-based methods. This paper presents an implementation of the Adaptive Stress Testing (AST) method applied to the collision avoidance (COLAV) system of a small passenger ferry. AST is a simulation-based technique which has shown promising results in safety assessment of aviation and automobile systems. Given a simulator of a system, AST uses reinforcement learning to optimize toward system failure, and returns the most likely failure scenarios. AST is here shown to successfully identify scenarios where the criteria for failure are met, which is when the ferry collides with an adversary vessel controlled by AST. However, most of the initial results exhibit failures where the COLAV system of the ferry is not responsible for the failure, making the results less valuable to system developers. To improve the relevance, augmentations are made to the optimization problem. The augmentations result in four distinct problem formulations presented in the paper. Finally, the results are clustered using an unsupervised machine learning method called Soft Dynamic Time Warping k-means clustering in order to present a general summary of the identified failure scenarios. Our results demonstrate the relevance and potential of AST for the maritime sector and illustrate how common drawbacks of AST can be circumvented by method adjustment.

Predictive Assessment of the Development of Unmanned Aviation System

Predictive Assessment of the Development of Unmanned Aviation System

Mathematical Model for Operation of Aviation Systems for Delivery of Special Means to Air and Earth Objects

The development of technologies allows the improvement of the algorithms for the operation of aviation systems for the delivery of special means to air and ground objects. The aim is to increase their efficiency, while facilitating the work of the crew in case of lack of time to complete the task. A mathematical model for the operation of this type of aviation systems for the supply of special equipment has been developed, which allows reducing the volume of the existing protocol for the implementation of the crew. It is proposed to use a common ballistic algorithm, combining different groups of special means of delivery to air and ground sites.

A Data-driven Integrated Safety Risk Warning Model based on Deep Learning for Civil Aircraft

With the extensive application of sensor technology, airlines accumulate a lot of flight data during fleet operations. Quick Access Recorder (QAR) is an important basis for aircraft state estimation and safety assessment, it records the operating status of various aircraft systems. However, the current application of QAR is mainly reflected in the investigation and verification of accidents, but it fails to apply such continuous real-time data to safety monitoring, risk prediction, and early warning. Therefore, this paper proposes a data-driven integrated safety risk warning model based on deep learning. Combined with the characteristics of QAR data and aircraft system failures, the failure mode and impact analysis (FMEA), cause chain analysis (CCA), long and short-term memory (LSTM), and other methods are used to describe the development of risks caused by system failures and predict the trend of flight parameters of each system, improve the ability to predict the risk and risk severity of the aviation system. Taking the Aircraft Refrigeration System (ARS) as the case object, the safety risk warning model is validated to calculate the risk level may face and find out the hidden hazard sources of civil aircraft operation in advance, to improve the safety level of civil aircraft operation

Taxonomy and Abstraction of the On-Demand Mobility Aviation System for Smart Cities

Taxonomy and Abstraction of the On-Demand Mobility Aviation System for Smart Cities

Price Discrimination Through Hidden City Options? A Data-Driven Study on the Extent and Evolution of Skiplaggability in the Global Aviation System

Price Discrimination Through Hidden City Options? A Data-Driven Study on the Extent and Evolution of Skiplaggability in the Global Aviation System

ДЕФОРМАЦИЯ ИЕРАРХИИ КРУПНЕЙШИХ АЭРОПОРТОВ МИРА И ЕВРОПЫ В УСЛОВИЯХ ПАНДЕМИИ COVID-19

The passenger turnover of almost all airports fell sharply from 30% to 90% in COVID-19 pandemic - most of all in those where the share of international passengers dominated, less - where domestic traffic prevailed. Changes in the rank of the hierarchy of the 60 largest airports in the world and 60 airports in Europe, caused by the consequences of the COVID-19 pandemic, are analyzed. A special technique has been developed for assessing the stability and variability of such a hierarchy. The values of three indicators of variability of the hierarchy of airports are compared in the pre-covid and in the first phase of the covid period. The level of internal instability in the global aviation system increased from 82 to 98%, in Europe – from 62 to 93%. The degree of rank lability of airports in the world has increased 8.8 times, in Europe – 4.5 times. The hierarchy of world and European air transport systems turned out to be relatively stable in the pre-covid era. In a pandemic, it has become deformed and very unstable. Its main deformers were airports in those countries where flight restrictions were lifted much earlier than in the rest of the world, as well as the new ones opened. Empirically, 5 types of variability in the hierarchy of airport systems have been identified: a very unstable hierarchy. The larger the territorial size of the airport system, the more changeable and unstable its hierarchical structure. Systems that are very large in terms of territorial size are more vulnerable to external influences (pandemics) than large or medium-sized ones, which is manifested in the degree of variability of their hierarchical structures.

تهديدات الأمن الإقليمي العربي في الميدان الخامس: نحو إستراتيجية للحماية

The world is moving towards increasing reliance on smart technologies throw adopting models of smart governments and smart cities, to get the gain of the Fourth Industrial Revolution in improving human lifestyle, and with accelerating the process of technological modernization that countries are going through, especially during the period of the spread of the Covid-19 virus, to ensure the continuation of human activity, while adhering to the instructions of quarantine and social distancing, the whole world has become more exposed to cyber threats. With the noticeable increase in the frequency of cyber attacks, and the increasing destructive capacity that has become capable of striking nuclear reactors and satellites, as well as critical infrastructure, this means that cyber war has become more likely than before, in a way that may be more fierce than other wars, Within a few minutes, thousands of deaths may occur if a cyber attack succeeds in targeting one of the vital facilities of countries, such as aviation systems or hospitals. Cyberspace is the main battlefield for this coming war. It is the fifth domain of the new battle after the four traditional fields - land, sea, air and outer space. Hence the importance of this paper, which discusses threats to Arab regional security in the fifth domain, these new threats resulting from the increasing dependence on cyberspace, and seeks to provide a vision that helps decision makers in formulating a national and Arab strategy to confront the risks of cyber threats facing Arab regional cyber security.

AN EVALUATION APPROACH FOR ELIMINATING THE FAILURE EFFECT IN GAS TURBINE USING FUZZY MULTIPLE CRITERIA

This paper demonstrated the fuzzy AHP combined with fuzzy VIKOR technique integrated with essentials of weight in order to overcome the risk evaluation process of the uncertainty in subjective perception and experience of human. Gas turbine has considerably expanded its role in several areas subsequent to the improvement in high efficiency and clean energy such as aviation and marine propulsion systems, electric power stations, and natural gas and petroleum transportation. However, the cost of various industrial plants and their relevant maintenance appear to be extremely expensive to be operated by these gas turbines. This paper aimed to cope with the essential elements of gas turbine including hydraulic-pneumatic equipment, electronic control equipment, and bearing equipment. The results have proved the bearing equipment to have been the most effected alternative, as being ensued by hydraulic-pneumatic equipment and electronic control equipment.

Modelling the volcanic ash plume from Eyjafjallajökull eruption (May 2010) over Europe: evaluation of the benefit of source term improvements and of the assimilation of aerosol measurements

Abstract. Numerical dispersion models are used operationally worldwide to mitigate the effect of volcanic ash on aviation. In order to improve the representation of the horizontal dispersion of ash plumes and of the 3D concentration of ash, a study was conducted using the MOCAGE model during the European Natural Airborne Disaster Information and Coordination System for Aviation (EUNADICS-AV) project. Source term modelling and assimilation of different data were investigated. A sensitivity study of source term formulation showed that a resolved source term, using the FPLUME plume rise model in MOCAGE, instead of a parameterised source term, induces a more realistic representation of the horizontal dispersion of the ash plume. The FPLUME simulation provides more concentrated and focused ash concentrations in the horizontal and the vertical dimensions than the other source term. The assimilation of Moderate Resolution Imaging Spectroradiometer (MODIS) aerosol optical depth has an impact on the horizontal dispersion of the plume, but this effect is rather low and local compared to source term improvement. More promising results are obtained with the continuous assimilation of ground-based lidar profiles, which improves the vertical distribution of ash and helps in reaching realistic values of ash concentrations. Using this configuration, the effect of assimilation may last for several hours and it may propagate several hundred kilometres downstream of the lidar profiles.

Prediction of Failure Time and Remaining Useful Life in Aviation Systems: Predictors, models, and challenges

In many important industries, such as aerial transportation, offshore wind turbine (OWT) structures, and nuclear power plants that reached or are near the end of their useful life, the structural conditions for continued usage are acceptable. Thus, safe continued operation with required modifications and assessment is more cost-effective than replacing them with a new system. To achieve this goal, many studies have been performed on predicting failure time and remaining useful life, especially in systems that require a very high level of reliability. The present review investigates the articles that predict the remaining useful life or failure time in aviation systems, from three perspectives: 1. Methods and algorithms, especially Machine Learning algorithms, which are growing in recent years in the field of Prognosis and Health Management. 2. Historical predictors such as working life history, environmental conditions, mechanical loads, failure records, asset age, maintenance information, or sensor variables and indicators that can be continuously controlled in each system, such as noise, temperature, vibration, and pressure.3. Challenges of researches on prediction of the failure time of flying systems. The literature assessment in this field shows that using diagnostic and prognostic outputs to identify possible defects and their origin, checking the system's health, and predicting the remaining useful life (RUL) is increasing due to market needs.

Ergonomic Risk Reduction Method in Aerospace Manufacturing

In the aerospace manufacturing, lots of processes cannot be automated and are performed manually by skilled workers. Because there exist some human error mistakes in such manual working processes, root cause investigations of these mistakes are indispensable and measures are implemented in working processes for preventing repetition of the same mistakes. Although skilled workers have strong confidence that they can complete their work with no mistake, there exist some cases that they cannot recognize their mistakes in practice. In such cases, root cause investigations cannot be performed and no measure is implemented. Such situation may become a serious risk in aerospace manufacturing because a tiny mistake can cause the serious mission failure of aviation system. To reduce such situation, the ergonomic risk reduction method is proposed. Skilled workers try to avoid frustration in performing their tasks and make mistakes through careless behavior. The cause of the frustration is discovered by ergonomic risk reduction method. Work risks can be removed by the progress of the working environment. Such risk reduction method contributes manufacturing organization resiliency. In this paper, we propose an ergonomic human error risk reduction method for skilled workers in Japanese domestic liquid rocket engine manufacturing.

Freezing of few nanometers water droplets

Water-ice transformation of few nm nanodroplets plays a critical role in nature including climate change, microphysics of clouds, survival mechanism of animals in cold environments, and a broad spectrum of technologies. In most of these scenarios, water-ice transformation occurs in a heterogenous mode where nanodroplets are in contact with another medium. Despite computational efforts, experimental probing of this transformation at few nm scales remains unresolved. Here, we report direct probing of water-ice transformation down to 2 nm scale and the length-scale dependence of transformation temperature through two independent metrologies. The transformation temperature shows a sharp length dependence in nanodroplets smaller than 10 nm and for 2 nm droplet, this temperature falls below the homogenous bulk nucleation limit. Contrary to nucleation on curved rigid solid surfaces, ice formation on soft interfaces (omnipresent in nature) can deform the interface leading to suppression of ice nucleation. For soft interfaces, ice nucleation temperature depends on surface modulus. Considering the interfacial deformation, the findings are in good agreement with predictions of classical nucleation theory. This understanding contributes to a greater knowledge of natural phenomena and rational design of anti-icing systems for aviation, wind energy and infrastructures and even cryopreservation systems.

Assessment of the Method of Merging Landing Aircraft Streams in the Context of Fuel Consumption in the Airspace

The most important directions in the field of sustainable development of air transport concern increasing the capacity of airports and improving the global civil aviation system, improving air traffic safety, and developing procedures to optimize the operation of the aviation system. An important area is environmental protection and measures to minimize the negative impact of civil aviation activities on the environment. Air traffic and the operation of airports generate adverse environmental effects, including greenhouse gas emissions, air pollution, and noise emissions. Due to the high intensity of aircraft maneuvers, the authors analyzed aircraft traffic in the area approaching the airport. It is essential to correctly line up for aircraft reporting from different entry points to the approach area to avoid waiting for landing. Misalignment of landing aircraft negatively impacts airport capacity, increases fuel consumption through more prolonged waiting times in space, and directly impacts air pollution. There are different ways to organize landing aircraft flows and other ways to merge these flows. The article aims to assess the method of combining the streams of landing aircraft and estimate the impact of such an organization on the increased fuel consumption of aircraft and thus on air pollution. The authors proposed a measure for assessing the quality of the landing queue, which was defined as the increase in flight time of aircraft in the approach area in relation to the nominal time, which was adopted as minimization. In order to obtain the results of research works, a model using a Petri net was developed, allowing for flexible mapping of concurrent processes and their effect analysis. Various methods of combining the streams of landing aircraft have been adopted: three-stage, two-stage, and single-stage. Then, simulation experiments were carried out, allowing the determination of whether the method of combining the streams of landing planes has an impact on the quality of the landing queue measured with the proposed index. The obtained results of the assessment can be used to estimate the increased fuel consumption of the aircraft.

Study of magneto-optical properties of GeO2-B2O3-P2O5-ZnO-Tb2O3 glass doped with different rare-earth ions

Paramagnetic magneto-optical glasses doped with different rare-earth ions, 32GeO2–15B2O3–5P2O5–3ZnO-45Tb2O3-RE (RE = 0, 1Ho, 1Pr, 1Er, 1Nd, 1Dy, or 1Ce), referred to as GBPZ-T45-RE magneto-optical glasses, were prepared using a high-temperature melting technique. The effects of rare-earth ion doping on the structure, physical parameters, and magneto-optical properties of these GBPZ-T45-RE glasses and the effects of incident-light wavelength and temperature on the values of the Verdet constants were researched. The refractive indexes and theoretical optical basicities of the glasses were obtained by theoretical calculations. Notably, GBPZ-T45-RE glasses exhibited a large Verdet constant and superior magneto-optical performance; especially, Ho3+ and Pr3+ ions were the most effective in improving the magneto-optical properties. In addition, the Verdet constants were affected by temperature. The Verdet constants of GBPZ-T45-Ho and GBPZ-T45-Pr were determined to be −172.44 and −175.22 rad/(T·m), respectively, under 633 nm light at 298.15 K, values that are significantly greater than that the commercial terbium gallium garnet TGG crystal (−134 rad/(T·m)). The Verdet constants of GBPZ-T45-Ho and GBPZ-T45-Pr under 633 nm light increased to −254.93 and −255.92 rad/(T·m), respectively, at 273.15 K. The excellent magneto-optical properties of these glasses should enable their widespread application in optics, electricity, magnetism, information, communications, military operations, aviation, satellite measurement and control systems, and other fields.

EUNADICS-AV early warning system dedicated to supporting aviation in the case of a crisis from natural airborne hazards and radionuclide clouds

Abstract. The purpose of the EUNADICS-AV (European Natural Airborne Disaster Information and Coordination System for Aviation) prototype early warning system (EWS) is to develop the combined use of harmonised data products from satellite, ground-based and in situ instruments to produce alerts of airborne hazards (volcanic, dust, smoke and radionuclide clouds), satisfying the requirement of aviation air traffic management (ATM) stakeholders (https://cordis.europa.eu/project/id/723986, last access: 5 November 2021). The alert products developed by the EUNADICS-AV EWS, i.e. near-real-time (NRT) observations, email notifications and netCDF (Network Common Data Form) alert data products (called NCAP files), have shown significant interest in using selective detection of natural airborne hazards from polar-orbiting satellites. The combination of several sensors inside a single global system demonstrates the advantage of using a triggered approach to obtain selective detection from observations, which cannot initially discriminate the different aerosol types. Satellite products from hyperspectral ultraviolet–visible (UV–vis) and infrared (IR) sensors (e.g. TROPOMI – TROPOspheric Monitoring Instrument – and IASI – Infrared Atmospheric Sounding Interferometer) and a broadband geostationary imager (Spinning Enhanced Visible and InfraRed Imager; SEVIRI) and retrievals from ground-based networks (e.g. EARLINET – European Aerosol Research Lidar Network, E-PROFILE and the regional network from volcano observatories) are combined by our system to create tailored alert products (e.g. selective ash detection, SO2 column and plume height, dust cloud, and smoke from wildfires). A total of 23 different alert products are implemented, using 1 geostationary and 13 polar-orbiting satellite platforms, 3 external existing service, and 2 EU and 2 regional ground-based networks. This allows for the identification and the tracking of extreme events. The EUNADICS-AV EWS has also shown the need to implement a future relay of radiological data (gamma dose rate and radionuclides concentrations in ground-level air) in the case of a nuclear accident. This highlights the interest of operating early warnings with the use of a homogenised dataset. For the four types of airborne hazard, the EUNADICS-AV EWS has demonstrated its capability to provide NRT alert data products to trigger data assimilation and dispersion modelling providing forecasts and inverse modelling for source term estimate. Not all of our alert data products (NCAP files) are publicly disseminated. Access to our alert products is currently restricted to key users (i.e. Volcanic Ash Advisory Centres, national meteorological services, the World Meteorological Organization, governments, volcano observatories and research collaborators), as these are considered pre-decisional products. On the other hand, thanks to the EUNADICS-AV–SACS (Support to Aviation Control Service) web interface (https://sacs.aeronomie.be, last access: 5 November 2021), the main part of the satellite observations used by the EUNADICS-AV EWS is shown in NRT, with public email notification of volcanic emission and delivery of tailored images and NCAP files. All of the ATM stakeholders (e.g. pilots, airlines and passengers) can access these alert products through this free channel.

Investigating the Impact of COVID-19 Disruption on the Decarbonisation Agenda at Airports: Grounded or Ready for Take-Off?

COVID-19 has had wide-ranging impacts on organisations with the potential to disrupt efforts to decarbonise their operations. To understand how COVID-19 has affected the climate change mitigation strategies of Airport Operators (AOs), questionnaires and semi-structured interviews with Sustainability Managers were undertaken in late 2020 amidst a period of disruption. While all reported that COVID-19 impacted delivery of interventions and projects to mitigate climate change, the majority stated that it would not impact their long-term climate goals, such as Net Zero by 2050. The most popular climate change mitigation interventions AOs intend to deploy between now and 2030 are on-site renewables and Electric Vehicles and related infrastructure. Engineered carbon removal interventions were considered highly unlikely to be deployed in this timeframe, with potential implications for Net Zero decarbonisation pathways. Despite the severe impacts of COVID-19 on the sector, results indicate that AOs remain committed to decarbonisation, with climate change action remaining the key priority for airports. Given ongoing financial and resource constraints, AOs will need to explore new business models and partnerships and nurture collaborative approaches with other aviation stakeholders to not only maintain progress toward Net Zero but “build back better”. Government support will also be needed to stimulate the development of a sustainable, resilient, low-carbon aviation system.

A Physics-Based Multidisciplinary Approach for the Preliminary Design and Performance Analysis of a Medium Range Aircraft with Box-Wing Architecture

The introduction of disruptive innovations in the transport aviation sector is becoming increasingly necessary. This is because there are many very demanding challenges that the transport aviation system will have to face in the years ahead. In particular, the reduction in pollutant emissions from air transport, and its impact on climate change, clearly must be addressed; moreover, sustainable solutions must be found to meet the constantly increasing demand for air traffic, and to reduce the problem of airport saturation at the same time. These three objectives seem to be in strong contrast with each other; in this paper, the introduction of a disruptive airframe configuration, called PrandtlPlane and based on a box-wing lifting system, is proposed as a solution to face these three challenges. This configuration is a more aerodynamically efficient alternative candidate to conventional aircraft, introducing benefits in terms of fuel consumption and providing the possibility to increase the payload without enlarging the overall aircraft wingspan. The development and analysis of this configuration, applied to a short-to-medium range transport aircraft, is carried out through a multi-fidelity physics-based approach. In particular, following an extensive design activity, the aerodynamic performance in different operating conditions is investigated in detail, the structural behaviour of the lifting system is assessed, and the operating missions of the aircraft are simulated. The same analysis methodologies are used to evaluate the performance of a benchmark aircraft with conventional architecture, with the aim of making direct comparisons with the box-wing aircraft and quantifying the performance differences between the two configurations. Namely, the CeRAS CSR-01, an open-access virtual representation of an A320-like aircraft, is selected as the conventional benchmark. Following such a comparative approach, the paper provides an assessment of the potential benefits of box-wing aircraft in terms of fuel consumption reduction and increase in payload capability. In particular, an increase in payload capability of 66% and a reduction in block fuel per pax km up to 22% is achieved for the PrandtlPlane with respect to the conventional benchmark, while maintaining the same maximum wingspan.

Threat impact analysis to air traffic control systems through flight delay modeling

Air traffic control (ATC) systems increasingly rely on communication, navigation, and other emerging digital technologies, making them more susceptible to external threats. To better analyze the different impacts, this paper proposes a new flight delay model that models the ATC system from two perspectives. In the air delay, we view the problem as an optimal path choice with a set of capacity constraints and consider the speed change, rerouting, and pathfinding. In the ground delay, the concept of cellular automata is extended to model the flight queue at each airport. Last, the system dynamics of delays are considered, and the two stages of modeling are combined using flight delay as an indicator to achieve an intuitive description of the impact on the system threat. Compared to the current state of the art, the model is shown to be a simple way to analyze the impact of different sophisticated threats. It also helps aviation system planners better understand the impact of different threats so that effective measures can be taken to improve system performance.

Multicarrier Spectral Shaping for Non-White Interference Channels: Application to Aeronautical Communications in the L-Band

In this paper, we investigate an algorithm to attain additive white Gaussian noise (AWGN) performance in spectrally non-white channels, using multicarrier communications, i.e., orthogonal frequency division multiplexing (OFDM) and filterbank multicarrier (FBMC). The non-white channel can be from non-white noise, or more commonly, interference. Our algorithm uses a simple optimization method to find usable subcarriers and assigns different power levels to the subcarriers to attain the equivalent AWGN channel bit error ratio (BER). Subcarriers that experience very high interference are assigned as null subcarriers. After describing our analysis, we show results for two non-white interference signal examples: the Gaussian pulse shaped distance measuring equipment (DME) pulses, and a classical rectangular-pulse interference signal. The DME example is pertinent for currently proposed aviation communication systems, where new multicarrier techniques, e.g., the L-band digital aviation communication systems (LDACS) have been designed as an inlay approach between the high-power DME channels in the L-band. Our results show how using this adaptive technique can improve performance and spectral efficiency, whereas fixed bandwidth schemes such as LDACS could suffer significant performance degradation. These results show the utility of this idea for future adaptive and cognitive radio applications for aviation or other non-white channels.