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Copyright of Canadian Public Policy is the property of University of Toronto Press and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this paper, we investigate the three-dimensional nature of dynamic stall. Conducting the investigation, the flow around a harmonically pitching National Advisory Committee for Aeronautics (NACA) 0012 airfoil is numerically simulated using Unsteady-Reynolds-Averaged Navier–Stokes (URANS) and multiple detached eddy simulation (DES) solvers: the Delayed-DES (DDES) and the Improved-DDES (IDDES). Two- and three-dimensional simulations are performed for each solver, and the results are compared against experimental measurements in the literature. The results showed that three-dimensional simulations surpass two-dimensional ones in capturing the stages of dynamic stall and predicting the lift coefficient values, with a distinguished performance of the DES solvers over the URANS ones. For instance, the IDDES simulations, as an inherently three-dimensional solver, predicted the necessary cascaded amalgamation process of vortices to form the adequate strength of the dynamic stall vortex. This vortex size and timing provided accurate and sufficient suction that resulted in identical matching of the numerical and experimental lift coefficients at the peak value. Hence, the hypothesis that dynamic stall has a three-dimensional nature is supported by the superiority of the three-dimensional simulation in all aspects. In conclusion, it is found that dynamic stall is intrinsically a three-dimensional phenomenon. [ABSTRACT FROM AUTHOR]

Background: Cognitive load (CL) management is essential in safety‐critical fields so that professionals can monitor and control their cognitive resources efficiently to perform and solve scenarios in a timely and safe manner, even in complex and unexpected circumstances. Thus, cognitive load theory (CLT) can be used to design virtual reality (VR) training programmes for professional learning in these fields. Objectives: We studied CL management performance through behavioural indicators in authentic VR flight training and explored if and to what extent physiological data was associated with CL management performance. Methods: The expert (n = 8) and novice pilots (n = 6) performed three approach and landing scenarios with increasing element interactivity. We used video recordings of the training to assess CL management performance based on the behavioural indicators. Then, we used the heart rate (HR) and heart rate variability (HRV) data to study the associations between the physiological data and CL management performance. Results and Conclusions: The pilots performed effectively in CL management. The experience of the pilots did not remarkably explain the variation in CL management performance. The scenario with the highest element interactivity and an increase in the very low‐frequency band of HRV were associated with decreased performance in CL management. Takeaways: Our study sheds light on the association between physiological indicators and CL management performance, which has traditionally been assessed with behavioural indicators in professional learning in safety‐critical fields. Thus, physiological measurements can be used to supplement the assessment of CL management performance, as relying solely on behavioural indicators can be time consuming. Lay Description: What is currently known about the subject matter: The advantages of VR training systems are clear in the safety‐critical fields.Cognitive load (CL) theory may help design of VR training.CL management is part of the professional competence in these fields. What this paper adds: The pilots performed well in CL management in VR flight training.The work experience of the pilot was not associated with the performance.The physiological data improved the explanatory level of the performance. The implications of study findings for practitioners: Pilots need time to get used to the immersive learning environment.Typical 1–2‐hour intensive VR flight training is not too demanding.The physiological data could complement CL management assessment. [ABSTRACT FROM AUTHOR]

This paper combines shape optimization and homogenization techniques in searching for the optimal design of microstructures in elastic scaffolds. The development of materials with specific properties is of practical interest, for example, for medical applications or for the development of lightweight structures in aeronautics. In particular, the optimal design of microstructures leads to fundamental questions for elastic porous media: how to calculate a microstructure leading to a target effective Hooke tensor. We propose a robust approach to find a design that is as insensitive as possible to domain variations. Our strategy is based on the shape derivative for the problem of achieving a prescribed effective tensor. We demonstrate the applicability and feasibility of our approach through numerical experiments. [ABSTRACT FROM AUTHOR]

In structural bonds, the interface between adherend and adhesive is nearly two-dimensional making the interface susceptible to minute quantities of contamination, which can cause weak bonds. Regulatory organizations such as the Federal Aviation Administration (FAA) often require redundant load paths in secondary-bonded primary-structures due to uncertainty in bond performance. To address this issue, the NASA Convergent Aeronautics Solutions (CAS): Adhesive Free Bonding of Composites (AERoBOND) project is investigating reformulated aerospace epoxy-matrix resins to enable reflow and diffusion of the resin at the joint interface during a secondary bonding and cure process that can eliminate the material discontinuity at the interface. Implementing in-situ process monitoring enables assessing the bond quality during processing rather than waiting for post-fabrication mechanical testing to be completed. In this paper, an in-situ ultrasonic inspection system is used to monitor the joining of three composite laminates assembled using the AERoBOND technique. For each panel, the amplitude of the wave reflection at the joint was measured throughout the cure cycle. The results indicate the timing and extent of reflow and cure of the epoxy resin at the joint. Factors indicating end of cure were ascertained and a metric was developed to qualitatively predict acceptable mode-II fracture toughness based on the ultrasonic amplitude at the joint line during cure. In addition, since the inspection system scans an area of the joint, high-resolution localized results can be obtained across the joint. [ABSTRACT FROM AUTHOR]

Copyright of Transactions on Aerospace Research is the property of Sciendo and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Purpose -- With the predicted rise in air traffic, a growing need exists to make the aviation industry more environmentally sustainable in the long-term future. Research has shown that the turbo-electric distributed propulsion system (TeDP) could be the next disruptive technology that has the potential to meet the ambitious environmental goals set for the N + 3 time frame. This however will require the use of superconductivity, application of high-temperature superconducting materials and cryogenic liquids. This paper provides a brief overview of the technology and further discusses the benefits, advantages and new opportunities that may arise from the application of the technology. Design/methodology/approach -- This paper provides a brief overview of the technology and further discusses the benefits, advantages and new opportunities that may arise from the application of the technology. Findings -- Implementation of superconducting technology is currently one of the greater challenges faced and hence this article also reviews some of the key considerations to enable utilisation of cryogenic fuels in the future. Originality/value -- This paper provides a viewpoint and reviews some of the work undertaken in the field. It also provides a perspective on some new possibilities and advantages from using TeDP with cryogenic fuels. [ABSTRACT FROM AUTHOR]

Field measurement of large aviation components is important in many fields of study. In this paper, a global data registration method based on the dynamic coded points is proposed. The system used in this method contains the local and global control binocular measurement systems. The local binocular measurement system measures the data of each subdomain as the local measurement data by scanning. The dynamic coded points, which are encoded based on time parameter as their encoded values, are projected to the measured object’s surface using a projector. Two sets of systems acquire the dynamic coded points to calculate their encoded values and match them automatically. These systems calculate the transformation relations between the local coordinate system and the global control coordinate system, so the local measurement data coordinates are integrated into the global control coordinate system through the transformation relations, achieving the global data registration. Experimental results in the laboratory show that the process of matching of dynamic coded points is accurate and has high robustness, and the global registration method based on the coded points proposed by this paper can eliminate the accumulated error, reaching the precision of 0.0150%. Field experimental results show that the registration method proposed in this paper satisfies the measurement requirements of large-scale aviation components. [ABSTRACT FROM AUTHOR]

The present study investigates the efficacy of sinusoidal trailing-edge (TE) serrations as a passive means for the reductions of airfoil broadband noise, theoretically and experimentally. Comprehensive parametric studies were conducted to determine the effect of serration amplitudes and wavelengths on the noise reduction performance of a National Advisory Committee for Aeronautics (NACA) airfoil. Initially, the present paper shows the use of the trailing-edge noise (TNO) model for the accurate predictions of the surface pressure spectrum near the TE and hence the far-field noise using the Wiener-Hopf method. The predicted spectra and the noise reduction levels showed good agreement with the measurements for a wide range of frequencies. The present study reveals that the local maximums of the overall noise reductions occur when the transverse turbulence integral length scale is either 1.2 or 0.2 times the serration wavelength, which corresponds to λ/Λt=0.833 or 5, where λ and Λt are the serration wavelength and integral length scale. One of the key findings of the paper is that the serration wavelength at which the highest noise reductions occur when the acoustic emissions vary inversely with the modified Strouhal number Sthm [i.e., wsste(ω)/wbl(ω)∝1/Sthm ] for narrow (i.e., small wavelengths) and wider serrations (i.e., large wavelengths), where wsste and wbl are the acoustic emissions radiated from the serrated and baseline airfoils. Further, the TE serrations are also observed to reduce leading-edge (LE) noise along with the self-noise, which indicates the efficacy of TE serrations in reducing the total far-field noise. [ABSTRACT FROM AUTHOR]

This paper proposes a solution to a certain two-alternative problem of aviation transportation optimal organization in conditions of uncertainty of the subjective preference functions. Conditional optimization of the objective functional containing the entropy of the individuals' operational effectiveness functions preferences is carried out in the framework of the simplest variational problem. the advantages of the described optimization approach are demonstrated in the generalized terms of the operational effectiveness functions for aviation transportation organization. [ABSTRACT FROM AUTHOR]

The National Aeronautics and Space Administration (NASA) has an ongoing Digital Transformation effort and to leverage and showcase the power of Digital Transformation, an effort is underway to develop an integrated, datacentric, model representing NASA's key process requirements. The task was divided into three phases: As Is modeling, Analysis, and To Be Planning. As part of this effort, a team has completed the first Phase I of the modeling task and is nearing completion of the second phase. This effort will capture the key elements as requirements, responsibilities, allocations, roles, products, and associated lifecycle elements. The scope of modeling included NASA's NPR 7120.5 (Project and Program Management), NPR 7123.1 (Systems Engineering) and NPRs 8705.2 (Risk classification for Robotic Missions) and 8705.4 (Human‐Rating Requirements for Space Missions). This paper will summarize the approach, scope, parsing patterns applied, metamodel, and associated workflows for the As‐Is modeling. It will also summarize the results and insights gleaned during that phase, including the review process. These insights have informed the analysis and will be discussed. The analysis modeling phase will also be summarized including how the stakeholders were engaged, how the common elements were handled and dispositioned, and will also describe some of the plans for the future of NASA NPDs and NPRs. [ABSTRACT FROM AUTHOR]

One of the key roles of National Aeronautics and Space Administration (NASA) is to help mitigate the risk and lower expenses associated with space exploration, science, and discovery to the point where industry and international partners are willing and able to profitably take on larger, more complex missions. To do this, the Agency must undertake a transformation to a more modern integrated Digital Engineering approach to mission definition and planning. This paper highlights NASA's journey in understanding what this Digital Engineering Transformation means for the Agency, the benefits of this transformation to human exploration definition and planning, and the benefits to the current Artemis campaign engineering capability portfolio. [ABSTRACT FROM AUTHOR]

This paper examined pilots' risk-taking behavioural intentions based on the theory of planned behaviour, as well as the impact of experience on behavioural intentions in adverse weather conditions. Two hundred and seventy-three airline pilots and flying cadets were divided into two groups and asked to complete a questionnaire based on two decision-making scenarios. This questionnaire measured pilots' intentions to take risks, along with the attitude towards the behaviour, subjective norms, perceived behavioural control (PBC), risk perception, and self-identity. The results showed that attitude, subjective norm, PBC, and risk perception explained 52% of the variance in behavioural intentions. Additionally, pilots' risk-taking decisions can be influenced by experience. Inexperienced pilots had a relatively stronger intention to take risks and a more favourable attitude towards risky behaviour. Moreover, pilots were more likely to rely on their own direct experience in the decision-making process. Practitioner summary: This study examined the pilots' risk-taking intentions under adverse weather conditions using a questionnaire based on the TPB theory. Results demonstrated that the TPB model can be applied to the risk-taking scenario and that experience can influence pilots' decisions. These findings have implications for improving flight safety and lowering accident rates. [ABSTRACT FROM AUTHOR]

This paper used correlational analysis to identify the influence of Total Solar Irradiance (TSI) in precipitation and temperature of the Philippines, representing the area in Manila, Cebu, and Davao from the year 1982 to 2019. The precipitation and temperature data were obtained from National Oceanic and Atmospheric Administration (NOAA), while the TSI data were downloaded from the National Aeronautics and Space Administration (NASA) daily database. The research found that there is a significant correlation between TSI and precipitation in the three major areas. Interestingly, there is a low negative correlation between TSI and temperature in Davao and a low significant correlation in Cebu. On the other hand, there is no significant correlation between TSI and temperature in Manila. [ABSTRACT FROM AUTHOR]

The article focuses on the utilization of the GEOS-Chem simulation with an application of multiple modifications to investigate the impact of the changes on atmospheric carbon dioxide (CO2) distributions. The GEOS-Chem is one of the models to cover a detailed accounting of CO2 emissions from both shipping and aviation. The most comprehensive online representation in a global 3-D CO2 transport model is the implementation of the chemical source of CO2.

Bird's formation flight is one of the best types of cooperation in nature. The bird's flight was the motivation of humans for flying. After one century of flight development, bird's formation flight was the motivation of humans for aircraft's formation flight. The closeness of aircrafts in formation flight and the effect of disturbances such as vortex make the formation flight control a challenging issue for control designers. This paper introduces a novel integration between guidance commands and system controller inputs. In recent papers the control system inputs were derived from approximate equations, and this approximation caused maneuver limitation. To tackle this problem, a new method is introduced, which employs proportional-integral-derivative (PID) controller in the integration block. This integrated guidance and control system employs the pure pursuit guidance to determine the unmanned aerial vehicle's acceleration command. A two-loop dynamic inversion technique is used for designing attitude and velocity controller, while the acceleration feedback control is used between the guidance system and attitude controller, which leads to increase in maneuverability of unmanned aerial vehicle's formation flight. The simulation results show that the proposed method can control the UAV's formation with sufficient accuracy in severe maneuvers. [ABSTRACT FROM AUTHOR]

Fault diagnosis and safety analysis of an aero-engine have attracted more and more attention in modern society, whose safety directly affects the flight safety of an aircraft. In this paper, the problem concerning sensor fault diagnosis is investigated for an aero-engine during the whole flight process. Considering that the aero-engine is always working in different status through the whole flight process, a flight status division-based sensor fault diagnosis method is presented to improve fault diagnosis precision for the aero-engine. First, aero-engine status is partitioned according to normal sensor data during the whole flight process through the clustering algorithm. Based on that, a diagnosis model is built for each status using the principal component analysis algorithm. Finally, the sensors are monitored using the built diagnosis models by identifying the aero-engine status. The simulation result illustrates the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

In recent years, multi-rotor unmanned aerial vehicle (UAV) has been widely used in various fields. It has the advantages of multifunctional, reasonable structure, easy operation and convenient for using. In this paper, based on the research results of the helicopter and the dynamic modeling method of rotor, we discuss several problems that need to be overcome in high altitude flight stability control. Combined with the rotor dynamics model, we give the simulation modeling method of multi - rotor UAV in high altitude flight wind field environment. This has laid a solid foundation for the subsequent multirotor UAV project development, control law debugging and flight control system software design. The results show that the control method can effectively improve the stability and flight quality of UAV. In addition, the emergency treatment methods and control strategies that introduced in this paper can improve the safe return rate of UAVs. In the broad sense of the stability control level, it can better guarantee the multi-rotor UAV flight safety. [ABSTRACT FROM AUTHOR]

Pulse-power technology has been widely used in inertial-confinement fusion, electron-beam accelerators, and the aeronautics and astronautics fields. However, particle contamination can reduce operational stability by altering the breakdown process. The objective of this paper is to study the effects of large numbers of metallic submicron particles on the breakdown characteristics. Particles were spontaneously generated via consecutive high-pulse-power breakdowns in compressed N2. In this paper, we adopted a plasma-diagnosis system that combines a laser scattering technique with laser shadow photography to detect particles originating from different materials. To distinguish the specific effects of particles, a double-electrode/double-pulse method was used to eliminate the unwanted effects of electrode erosion. After thousands of consecutive breakdowns, numerous particles were unexpectedly found to suspend and accumulate in the inter-electrode gap rather than fall to the bottom. These particles mainly stemmed from the anode and were identified as either metallic conducting nanoparticles or submicron particles. Furthermore, their density continuously increased and remained at a high level for a long time. This converted the insulating medium from a pure gas to a mixture with numerous metallic particles. In this case, the probability of breakdowns involving particles increased and their mean breakdown voltage showed a downward trend. According to our analysis of the field-enhancement process, these small particles alone can neither cause field emission nor trigger a microdischarge. However, their collective effects could be significant if they were involved in the breakdown channel. [ABSTRACT FROM AUTHOR]

This paper investigated the effects of vertical vibration on sitting comfort in civil aviation, with particular attention to high-frequency components (i.e. 30‒100 Hz). We generated 24 vibration stimuli at four positions (i.e. the co-pilot, front, middle, and rear seat positions) in the aircraft cabin, with magnitudes ranging from 0.05 to 2 ms−2 r.m.s. and durations of 10 s. Twenty-four subjects (12 males and 12 females) judged the vibration discomfort using a category-ratio method. We found a significant effect of high-frequency vibration on comfort: vibration stimuli at the middle and rear seats contained more energy at high frequencies and caused significantly greater discomfort than those at the co-pilot and the front seats. However, this effect became less significant with increasing magnitudes of vibration stimuli. The discomfort predicting models provided more accurate results by amplifying weighting factors for high-frequency vibration than those using standardised weightings (i.e. Wb and Wk weightings). Practitioner summary: The severity of high-frequency vibration for sitting comfort was usually underestimated. We investigated vibration discomfort at various seat positions in an aircraft cabin. Vibration at the middle and rear seats contained more high-frequency components and caused more discomfort. This work provided accurate predicting models of discomfort using the modified weighting. [ABSTRACT FROM AUTHOR]

In an innovative system, it is essential to keep under control the crucial development phases, which should consider several aspects involving, for instance, the modeling or the assessment of suitable analytical representations. Aiming to pursue a final demonstration to verify the actual capability of an engineering idea, however, some fundamental elements may have been partially considered. Many projects state the initial and final technology readiness level based on the famous scale introduced by the US National and Aeronautics Space Administration (NASA) many years ago and now widespread in many fields of technology innovation. Its nine-step definition provides a high-level indication of the maturity of the observed innovative system. Trivially, the resolution of that macroscopic meter is not made for catching advancement details, but it rather provides comprehensive information on the examined technology. It is, therefore, necessary to refer to more sophisticated analysis tools that can show a more accurate picture of the development stage and helps designers to highlight points that deserve further attention and deeper analysis. The risk is to perform a very good demonstration test that can miss generality and remain confined only to that specific experimental campaign. Moving on to these assumptions, the authors expose three realizations of theirs concerning aeronautic morphing systems, to the analysis of a well-assessed Technology Readiness Level instrument. The aim is to define the aspects to be further assessed, the aspect to be considered fully mature, and even aspects that could miss some elementary point to attain full maturation. Such studies are not so frequent in the literature, and the authors believe to give a valuable, yet preliminary, contribution to the engineering of breakthrough systems. Without losing generality, the paper refers to the 2.2 version of a tool set up by the US Air Force Research Laboratory (AFRL), and NASA, with the aim to standardize the evaluation process of the mentioned nine-step TRL. [ABSTRACT FROM AUTHOR]

Purpose: Since the inception of aerospace engineering, reducing drag is of eternal importance. Over the years, researchers have been trying to improve the aerodynamics of National Advisory Committee for Aeronautics (NACA) aerofoils in many ways. It is proved that smooth-surfaced NACA 0012 aerofoil produces more drag in compressible flow. Recent research on shark-skin pattern warrants a feasible solution to many fluid-engineering problems. Several attempts were made by many researchers to implement the idea of shark skin in the form of coatings, texture and more. However, those ideas are at greater risk when it comes to wing maintenance. The purpose of this paper is to implement a relatively larger biomimetic pattern which would make way for easy maintenance of patterned wings with improved performance. Design/methodology/approach: In this paper, two biomimetic aerofoils are designed by optimizing the surface pattern of shark skin and are tested at different angles of attack in the computational flow domain. Findings: The results of the biomimetic aerofoils prove that viscous and total drag can be reduced up to 33.08% and 3.68%, respectively, at high subsonic speed when validated against a NACA 0012 aerofoil. With the ample effectiveness of patched shark-skin pattern, biomimetic aerofoil generates as high as 10.42% lift than NACA 0012. Originality/value: In this study, a feasible shark-skin pattern is constructed for NACA 0012 in a transonic flow regime. Computational results achieved using the theoretical model agree with experimental data. [ABSTRACT FROM AUTHOR]

The development of aviation market in Southeast Asia after the Covid-19 pandemic is promising. More aircraft are delivered to the Asia-Pacific region, including the Association of South East Asian Nations (ASEAN) Member States. The introduction of ASEAN Open Skies (also known as ASEAN Single Aviation Market) a decade earlier together with ASEAN Economic Community Blueprint 2025 goals for an integrated and cohesive regional economy highlight the importance of a seamless air connectivity. Liberalisation of the airline industry in ASEAN Member States is crucial to restart the airline industry prepandemic and to grasp the so-called Asian century momentum. However, ASEAN Member States are reluctant towards liberalisation efforts, maintaining protectionism on both freedoms of the air (traffic rights) as well as foreign direct investment (ownership and control). Existing legal framework at regional level, namely ASEAN Framework Agreement on Services (AFAS) and ASEAN Trade in Services Agreement (ATISA), only received lukewarm attention from ASEAN Member States. This article discusses the urgency to recall the commitment of a gradual liberalisation based on AFAS and ATISA among the ASEAN Member States, the implementation of which will lead to the establishment of a regional community carrier which benefits ASEAN citizens. [ABSTRACT FROM AUTHOR]

This paper investigated the discomfort caused by vertical whole-body vibration (WBV) over 20 minutes using data recorded at the front, middle, and rear seats of the passenger cabin in civil aviation during a cruising flight. Twenty-four subjects experienced each stimulus at 0.5 ms−2 r.m.s. and judged discomfort at various moments (i.e. 1/6, 5, 10, 15, and 20 min) using a category-ratio method. The difference in discomfort due to high-frequency vibration components vanished after 10 min. Based on Stevens' power law, a method is developed to estimate long-term vertical WBV discomfort by considering the static discomfort and an interaction coefficient between vibration and static discomfort as parameters. The proposed estimation method showed high accuracy with determination coefficients (R2) higher than 0.97 and good linearity with values of growth rates 0.95, 1, and 0.95 for the vertical WBV discomfort at the front, middle, and rear seat positions in the aircraft cabin. Practitioner summary: An estimation method for the discomfort caused by vertical WBV considering the duration and static sitting discomfort is developed. This method can provide accurate discomfort estimating for long-term vibration exposure, e.g. in civil aviation during a cruising flight, by introducing an 'interaction term' between static and dynamic discomfort. [ABSTRACT FROM AUTHOR]

Aviation safety is and always will be a primary priority. Technological advancements, improved pilot training, and improved procedures have all played a significant role in this regard over the years. According to several studies, human factors currently account for over 70% of all accidents. As a result, in order to improve aviation safety, the focus should be on the variables that contribute to those errors, with mental health being one of the most critical. Fatigue, stress, anxiety, depression, and burnout are all connected with poor mental health in aviation. This paper presents a systematic review of articles on pilots' mental health, together with an anonymous survey to 182 pilots focused on understanding how pilots, airlines and aviation organizations handle pilots' mental health. According to the survey, pilots bear most of the responsibility and are the ones who experience the consequences if their mental health declines. Additionally, it seems that pilots do not view therapy as a viable choice; even though the majority of respondents said they would turn to therapy if they felt the need, many believed that doing so would worsen their mental health. From both the literature review and the survey results, it is concluded that the complex and subjective nature of mental health imply that this is not a job for any single organization, but that a collective work across all the aviation industry is needed, for which all must be responsible. [ABSTRACT FROM AUTHOR]

The 2012 Eurocorr meeting was held at the Sheraton Maslak hotel, Istanbul from 9-13th September 2012. The focus of the meeting was 'Safer world through better corrosion control'. The meeting attracted over 650 delegates and over 360 papers and 125 posters were presented during the 27 sessions and workshops. Parts 1-4 review the technical sessions over four issues with technical sessions on: corrosion in the nuclear industry, environmentally assisted corrosion, corrosion education, tribocorrosion, corrosion in drinking water supplies and aerospace corrosion covered in this report. [ABSTRACT FROM AUTHOR]

The paper presents the results of a cavitation in a slit channel study and offers an analytical description of cavity development. Special emphasis was placed on examining partial cavitation near a NACA 0012 hydrofoil (NACA – the National Advisory Committee for Aeronautics) inside slit channels of different geometries. Experimental investigation was carried out via high-speed imaging and the laser Doppler anemometry (LDA) method. The experimental data showed that the local flow velocity in hydrofoil leading edge area increased abruptly under arising cavitation. In addition, occurrence of cavitation raised flow velocity pulsation by 20%. In the case of a shorter channel, cavity growth occurred at higher cavitation numbers than for a longer channel. The cavity growth velocity was higher for a shorter channel. We showed that the tendency of partial cavitation development in the slit channel can be described as follows: L / C ∼ σ −1, where L is the cavity length; C is the hydrofoil chord; σ is the cavitation number; and parameter A changes as the slit channel length is varied. Comparison of cavitation development near hydrofoil at different attack angles α inside the slit channel with a three-dimensional (3D) cavitation tunnel was conducted. Cavitation in the slit channel occurred at lower σ /2 α values compared to 3D cavitation flow around the hydrofoil. To directly compare lengths of the attached cavities arising in slit channels and 3D cavitation tunnels, an additional parameter is proposed, taking into account friction of the slit channel: K = λ · l / D. This parameter allowed us to quantitatively compare the characteristics of cavitating hydrofoils in slit channels and 3D tunnels. The paper provides the governing criteria of the cavitation in the slit channel. Our results propose the physical foundations for the development of cavities in the slit channel. [ABSTRACT FROM AUTHOR]

An important role that the leading-edge cross-section shape plays in the wing flight performance is well known in aeronautics. However, little is known about the shape of the leading-edge cross section of an insect's wing and its contribution to remarkable qualities of insect flight. In this paper, we reveal, in the first time, the shape of the leading-edge cross section of a cicada's wing and analyze its variability along the wing. We also identify and quantify similarities in characteristic dimensions of this shape in the wings of three different cicada species. [ABSTRACT FROM AUTHOR]

Recently, there has been growing interest in developing unmanned aircraft systems (UAS) with advanced onboard autonomous capabilities. This paper describes the current state of the art in autonomous rotorcraft UAS (RUAS) and provides a detailed literature review of the last two decades of active research on RUAS. Three functional technology areas are identified as the core components of an autonomous RUAS. Guidance, navigation, and control (GNC) have received much attention from the research community, and have dominated the UAS literature from the nineties until now. This paper first presents the main research groups involved in the development of GNC systems for RUAS. Then it describes the development of a framework that provides standard definitions and metrics characterizing and measuring the autonomy level of a RUAS using GNC aspects. This framework is intended to facilitate the understanding and the organization of this survey paper, but it can also serve as a common reference for the UAS community. The main objective of this paper is to present a comprehensive survey of RUAS research that captures all seminal works and milestones in each GNC area, with a particular focus on practical methods and technologies that have been demonstrated in flight tests. These algorithms and systems have been classified into different categories and classes based on the autonomy level they provide and the algorithmic approach used. Finally, the paper discusses the RUAS literature in general and highlights challenges that need to be addressed in developing autonomous systems for unmanned rotorcraft. © 2012 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

This Special Issue highlights the latest enhancements in the abatement of noise and vibrations of aerospace and automotive systems. The reduction of acoustic emissions and the improvement of cabin interior comfort are on the path of all major transportation industries, having a direct impact on customer satisfaction and, consequently, the commercial success of new products. Topics covered in this Special Issue deal with computational, instrumentation and data analysis of noise and vibrations of fixed wing aircrafts, satellites, spacecrafts, automotives and trains, ranging from aerodynamically generated noise to engine noise, sound absorption, cabin acoustic treatments, duct acoustics and vibroacoustic properties of materials. The focus of this Special Issue is also related to industrial aspects, e.g.,: numerical and experimental studies have been performed for an existing and commercialized engine to enable design improvements aimed at reducing noise and vibrations; moreover, an optimization is provided for the design of low vibroacoustic volute centrifugal compressors and fans whose fluids should be strictly kept in the system without any leakage. Existing procedures and algorithms useful to reach the abovementioned objectives in the most efficient way are illustrated in the collected papers. [ABSTRACT FROM AUTHOR]

This paper focuses on major trends in the aviation industry, including the differences between large and regional airports. Marketing strategy is a part of corporate strategy, which has to be analysed, evaluated and implemented in line with other strategy items. This paper will show why switching from the 4P model to implement the 4C model is more suitable for small airports. The paper also describes the consequences of the change regarding customers, airlines and airports as well as the tangible results of such implementation. [ABSTRACT FROM AUTHOR]

Purpose ? This paper aims to present a proposal of a simple analytical redundancy method using for virtual attitude reference system design. The main idea of the project is applied typical on-board general aviation aircraft equipment for solving pitch and bank angles. Design/methodology/approach ? The presented solution is based on satellite navigation and air data computer signals, which are independent from basic attitude and heading reference system. The concept described is related to the kinematics relations and aerodynamic forces formulas. Findings ? The paper shows that the virtual attitude sensors are used by failure detection and reconfiguration subsystem and as a standby attitude reference system for general aviation aircraft equipped with augmentation control system applied for improving safety and efficiency handling qualities of aircraft. Originality/value ? This solution allows improvements in operating properties of already existing and newly designed executive aircraft, as well as establishing a higher level of flight safety. [ABSTRACT FROM AUTHOR]