bluuebunny/crossref_metadata_2025 huggingface dataset:
The occurrence of insectivores (Mammalia, Eulipotyphla) in Georgia from 1864 through to 2022
Authors: Kandaurov Andrei , Bukhnikashvili Alexander , Sheklashvili Giorgi , Natradze Ioseb
Published: July 2023

Of the 108 species that occur in Georgia, ten species are insectivores belonging to the order Eulipotyphla. Forty percent of them are endemic to the Caucasus and sixty percent are endemic to the Middle East, including the Caucasus. Up to now, no comprehensive data on the distribution of insectivores in Georgia have been available.

The aggregated standardised data on the occurrence of small mammals can be applied to resource management, biogeography, ecological and systematic studies and to the planning of nature conservation efforts. Hereafter, the attempt to provide accumulated in one paper all known points of insectivores' occurrence in Georgia and make it available to researchers via the open repository GBIF is presented.

The dataset is based on both literature data from 30 published sources (251 records), collection vouchers from four main zoological collections containing vouchers from Georgia (415 records) and authors' fieldwork results (217 records). The occurrence points of the specimens stored in collections and museums have been extracted from museum voucher labels and museum journals.

All known sampling points of insectivores in Georgia are collected in one dataset for the first time. Our field surveillance data reach about 24.6% of the records. Most of our data collected since 2003 have not been published yet. About 28.4% of the records have been recovered from publications in Russian and Georgian languages and 47% of the dataset records are derived from collections.
Important first steps towards designing the freshwater, marine and terrestrial Essential Biodiversity Variable (EBV) workflows for the European Biodiversity Observation Network
Authors: Lumbierres Maria , Kissling W. Daniel
Published: July 2023

The EuropaBON project aims to co-design a European Biodiversity Observation Network by utilising Essential Biodiversity Variables (EBVs) as the foundation for its monitoring system. To co-design the workflow steps for each EBV, the project organised a virtual workshop to engage a diverse group of experts and stakeholders. The workshop focused on describing various workflow components, identifying future needs for EBV implementation and specifying the relative importance of different monitoring techniques for each EBV. With 520 participants from 49 countries, the workshop benefited from a large stakeholder engagement and a wide range of expertise across realms, EBV classes, monitoring techniques and workflow components. During the 3-day workshop (2 hours per day), participants captured different workflows components (i.e. data collection and sampling, data integration and modelling), specified current EU or national initiatives and identified emerging tools and future needs for all 70 currently proposed EBVs. By the end of the workshop, all 70 templates of EBV workflows contained details about workflow components and future needs. Specific future needs for data collection and sampling highlighted by participants were to increase sampling efforts (e.g. number of sites, geographic coverage, sampling frequency and taxonomic scope), to develop and better incorporate novel monitoring techniques (e.g. eDNA, remote sensing and digital sensors) and to create new or improved sampling designs at a European scale. For data integration, combining and harmonising data from diverse sources and data collectors and developing standards and protocols were mentioned as key needs. For modelling, participants especially highlighted the need to develop spatially-explicit models or improve other types of existing models, ideally with open-source software and code. Next steps for designing EBV workflows are to analyse the gathered workshop information, to provide detailed descriptions of EBV workflows and to formulate specific recommendations for the development of a European Biodiversity Observation Network. Recommendations for each monitoring technique (structured in-situ monitoring, citizen science, digital sensors, genetics, satellite remote sensing and aerial remote setting) will also be identified. The gathered information will contribute to the co-design of the European Biodiversity Observation Network and to supporting the establishment of a Biodiversity Monitoring Coordination Centre in Europe.
Multi-modal feature selection with self-expression topological manifold for end-stage renal disease associated with mild cognitive impairment
Authors: Song Chaofan , Liu Tongqiang , Wang Huan , Shi Haifeng , Jiao Zhuqing
Published: July 2023

Effectively selecting discriminative brain regions in multi-modal neuroimages is one of the effective means to reveal the neuropathological mechanism of end-stage renal disease associated with mild cognitive impairment (ESRDaMCI). Existing multi-modal feature selection methods usually depend on the Euclidean distance to measure the similarity between data, which tends to ignore the implied data manifold. A self-expression topological manifold based multi-modal feature selection method (SETMFS) is proposed to address this issue employing self-expression topological manifold. First, a dynamic brain functional network is established using functional magnetic resonance imaging (fMRI), after which the betweenness centrality is extracted. The feature matrix of fMRI is constructed based on this centrality measure. Second, the feature matrix of arterial spin labeling (ASL) is constructed by extracting the cerebral blood flow (CBF). Then, the topological relationship matrices are constructed by calculating the topological relationship between each data point in the two feature matrices to measure the intrinsic similarity between the features, respectively. Subsequently, the graph regularization is utilized to embed the self-expression model into topological manifold learning to identify the linear self-expression of the features. Finally, the selected well-represented feature vectors are fed into a multicore support vector machine (MKSVM) for classification. The experimental results show that the classification performance of SETMFS is significantly superior to several state-of-the-art feature selection methods, especially its classification accuracy reaches 86.10%, which is at least 4.34% higher than other comparable methods. This method fully considers the topological correlation between the multi-modal features and provides a reference for ESRDaMCI auxiliary diagnosis.
Une encoche dans le trop-plein répressif
Authors: Sizaire Vincent
Published: July 2023

Tirant tous les enseignements de la jurisprudence de la Cour de Luxembourg, la chambre criminelle de la Cour de cassation affirme sans équivoque la subsidiarité de la réponse judiciaire en matière de police des étrangers, laquelle ne peut être mise en œuvre que dans la mesure où la procédure administrative d’éloignement n’a pas abouti. Dans un contexte où la tendance jurisprudentielle est au cumul des procédures répressives, la portée de cette décision demeure toutefois des plus incertaines.
AI Technology and Academic Writing
Authors: Storey Valerie A.
Published: July 2023

Evidence shows that artificial intelligence (AI) has become an important subject in academia, representing about 2.2% of all scientific publications. One concern for doctoral programs is the future role of AI in doctoral writing due to the increase in AI-generated content, such as text and images. Apprehensions have been expressed that the use of AI may have a negative impact on a doctoral student's ability to think critically and creatively. In contrast, others argue that using AI tools can provide various benefits resulting in rigorous research. This conceptual article first discusses the developing relationship between AI and dissertation writing skills. Second, the article explores the origins of the traditional dissertation and outlines 21st-century dissertation options which reflect contextual needs and utilization of AI. Third, identified writing challenges are highlighted before turning to an in-depth examination of AI-generated tools and writing craft skills required to complete the five chapters of a traditional dissertation.
Ethical, Cultural, and Historical Leadership Implications of Conducting Public Health Research on Minority Populations
Authors: Huff Allison J. , Burrell Darrell Norman , Lewis Eugene J. , Ingle Aleha M. , Vestal Kyleigh Elizabeth , Richardson Kevin
Published: July 2023

The study focuses on ethical and cultural research into the public health sector. The content analysis of research identifies disproportionate knowledge of implications affecting the misappropriated, disenfranchised, and institutionalized minority segments of the general population affected by COVID-19 cases. Historic mistreatment of minority individuals, inmates, and the military has left a lasting negative impression of clinical research on minority groups. In 1932, the United States Public Health Service (USPHS) began a public health research study on the lethality of syphilis using African American men from Macon County, Alabama as research subjects. Referred to as the Tuskegee Syphilis Studies (or Tuskegee Experiments), researchers monitored 600 subjects, 399 of which were previously infected with the syphilis bacteria. This article looks at the historical contexts of the lack of bioethics during Tuskegee Experiments and how it currently influences African-Americans reluctance early on to get the COVID-19 vaccines and reluctance to participate in clinical trials research.
The Effect of E-Learning and Traditional Teaching Done Hand-in-Hand for First-Year M.B.B.S. Students
Authors: Chanemougavally J.  , Shruthy K. M.  , Sudhakar Selvaraj , Sasirekha M.
Published: July 2023

Medical education is experimenting with different tools to make teaching-learning more compatible with the medical curriculum. One such addition is blended learning, which combines traditional teaching with e-learning. The study aims to assess the effectiveness of combining e-learning and traditional face-to-face gross anatomy teaching in undergraduate medical students. This collaborative study was done in the Department of Anatomy, A.C.S Medical College and Hospital, Dr. M.G.R. Educational and Research Institute (Deemed to be University). One hundred fourteen students volunteered to participate in the study. Six topics from the gross anatomy of the abdomen were chosen for the study. An overall pre-test questionnaire was delivered with the didactic lectures. Another pre-test questionnaire was given about the selected topic before sharing the online learning materials. A post-test questionnaire in Google form was collected at the end of the day. Feedback was collected from all study participants.
Presidential Attack Risk
Authors: Chen Renee Rui , Xiao Xiao , Chen Kun , Ren Jifan
Published: July 2023

The prevalence of social media has inspired multiple researchers to investigate the value of information on various platforms. However, most studies focus on integrating individual views (the wisdom of the crowd), and few studies investigate just one person's effect. To close this gap, this article investigates the impact of Trump's tweets on stock markets. Based on intraday stock market data, this study uses an event study to test the immediate reaction of the stock markets in both the Chinese and U.S. markets. Next, with ordinary least squares (OLS) regression, this study testes the effect of tweets' content features on the returns and volatility of the Chinese and U.S. indices. The results show that Trump's tweets impacted the financial market, especially the returns of the U.S. stock market during the COVID-19 pandemic. With additional analyses based on industry indices and time frequencies, the researchers found that Trump's sentiment on Twitter affected the Chinese financial industry during the trade war and impacted the Chinese pharmaceutical industry during the pandemic.
Development of leather from the skin of yellowfin tuna (Thunnus albacares) and Asian sea bass (Lates calcarifer) using an environmentally friendly tanning technique
Authors: Herath H. M. N. S. , Jayawardhana H. A. T. N. , Mahagedara H. B. M. W. C. K. , Mihiran B. D. M.
Published: July 2023

Yellowfin tuna (Thunnus albacares) and Asian sea bass (Lates calcarifer) are highly demanded export fish species in Sri Lanka. The objective of the present study was to prepare leather from the skin of T. albacares and L. calcarifer using tanning media prepared with black tea (Camellia sinensis) powder and table salt (NaCl). Black tea powder and table salt concentrations were increased by 10 grams (initial weight; 10 gL-1) and 1 gram (initial weight; 1 gL-1), respectively each day for 12 d. Skins were dipped in each concentration for 24 hrs. After additional water was removed, vegetableoil-applied skins were stretched and air-dried at room temperature. The percentage of ash, fat,protein, and tensile strength of the leather prepared from L. calcarifer skin was significantly higher(P<0.05) compared to leather prepared from T. albacares skin. The percentage of moisture, averagethickness, and tear strength of the leather prepared from the T. albacares skin were significantlyhigher (P<0.05) than the leather prepared from L. calcarifer skin. According to the ΔL*, Δa*, andΔb* values, leather prepared from T. albacares skin has lighter, greener, bluer and L. calcarifer skinhas darker, greener, yellower colours respectively. There are no significant colour differences betweenprepared leathers (P>0.05). Sensory evaluation results indicated that, finishing, appearance,handling, and overall acceptability, of leather wallet prepared from T. albacares has higherconsumer acceptance. The study demonstrated the effectiveness of this novel method for preparationof leather from T. albacares and L. calcarifer skin. In conclusion, T. albacares skin is more suitablefor fish leather preparation using the above described tanning method.
Retrospective Study; Comparison of the Stride Pattern of Elite 400 meters Hurdlers in Sri Lanka with Elite Athletes in Asia and the World
Authors: Bandara T. G. G. S. T. P. , Perera D. S. L. , Hapuarachchi H. A. C. S.
Published: July 2023

This study aimed in identifying and comparing the stride pattern in the 400mH event of the top 10 Sri Lankan, Asian, and World levels athletes of 2019 top list. A retrospective research design was used and following a selective sampling method top 10 athletes were selected from each group as subjects (N 30). Each athlete’s 400 mH 2019 season best video was analysed. 400m event timings were recorded from World Athletics. Kinovea software version 0.8.26 and Minitab software version 19 were used for data analysis. One-way ANOVA, Tukey test and Pearson’s correlation coefficient tests were performed. It was significantly different from the 1st hurdle to the 6th hurdle in all three groups. Tukey test further revealed a significant difference in Sri Lankan athletes from the start to the 1st hurdle, and from the 6th hurdle to the 10th hurdle. Moreover, only the world-level athletes were significantly different from the 10th hurdle to the finish line. The 400m time was significantly different in all three levels. World-level athletes’ group have a moderate, and the Asian-level athlete group have a very weak correlation while the Sri Lankan athlete group have a strong correlation between 400m time and 400 mH time (r= 0.607, 0.135, 0.849) respectively. In conclusion, to improve the level of performance among Sri Lankan 400mH athletes compared with the other levels, the times taken from start to the first hurdle, between hurdles, and from last hurdle to the finish line needed to be improved while improving 400m performance.
Identification of Reasons for Culpable Homicides and Attempted Murders: A Case Study for the Kelaniya Police Division
Authors: Weerakoon H. L. A. , Chandrasekara N. V.
Published: July 2023

Culpable Homicides and attempted murders are ultimate crimes that could create ripple effects on a society which could go far beyond the original loss of human life. Owing to the unpredictable nature of such crimes that require complex investigations the objective of this study was to come up with an appropriate model to identify the reason for a culpable homicide or an attempted murder using a statistical approach. This study use data collected from 12 Police stations in Kelaniya Police Division relating to the incidents happened between 2010 and 2020. The Pearson Chi-square test was used in identifying the influential explanatory variables. Out of the 18 variables, 8 predictors including Weapon used, Relationship, Location, Civil Status of the perpetrator were statistically associated with the identified reasons at 5 % level of significance. Multinomial logistic regression followed by four data mining models including classification tree, support vector machine (SVM), k-nearest neighbour (KNN), and probabilistic neural network (PNN) were employed initially with a training and testing set which was randomly selected in the ratio 90:10. The 4 data mining models were then fitted separately by using the bagging technique. The accuracies were compared using the confusion matrixes and rates of misclassifications of the critical classes. Out of the fitted models, the highest accuracy of 93.75 % was shown by the PNN model with a spread of 0.6. The identified model can be used as a decision support tool by crime investigators and relevant authorities for wise decision making.
T55 Gas Turbine Engine Bleed Band Actuator Housing Re-Design
Authors:   US Army CCDC AvMC, Cass Wesley
Published: July 2023

The continual replacement of the bleed band actuator caused a supply shortage resulting in production work stoppage. A re-design effort restored the actuator housing through rework modification of a sleeve repair. The re-design substantion is presented along with the qualification test and manufacturing process. Significant value engineering savings and increased supply readiness resulted from the re-design effort for the U. S. Army. However, the re-designed sleeved actuator housing became costly and inefficient over time and subsequently stopped. The overhaul discrepancy is still present on the newer T55 gas turbine engine model. A review of new repair technology available identified another solution that does not generate hazardous industrial waste. That solution is cold spray technology. Cold spray solid state additive technology is evaluated for re-design of the housing as comparison to the existing sleeve re-design. Cost decrease and manufacturing efficiency increase are both a result from this evaluation. Two cold spray powders presented are options for the re-design housing. While both powders provide a better overall solution to the sleeve re-design, the cold spray hard coat powder appears to provide improved wear resistance, e.g. 20 times better than hexavalent chrome plating.
Inflow Based Flight Dynamics Modeling Improvements for the Sikorsky X2 Technology Demonstrator
Authors:   US Naval Academy, Juhasz Ondrej ,   Sikorsky a Lockheed Martin Company, Xin Hong ,   US Army CCDC AvMC, Tischler Mark
Published: July 2023

Dynamic inflow models are required to correctly capture the bare-airframe dynamic response of a rotorcraft, for stability analysis and control system design. To properly determine the impact of inflow on the flight dynamics response of a coaxial rotorcraft, interaction between the wakes of the upper and lower rotors must be accounted for within the dynamic inflow model. Enhancements to existing dynamic inflow models are investigated within this paper and compared to flight data for the Sikorsky X2 Technology DemonstratorTM. The first improvement method introduces wake distortion effects into an existing set of coaxial rotor dynamic inflow equations. The second method uses system identification techniques to identify a full coaxial rotor dynamic inflow model from a free-vortex wake, which intrinsically captures the effect of wake geometry changes on rotor air loads. The results show that both the inclusion of wake distortion and the inflow model identification greatly improve alignment with flight data. The updated models match flight data nearly perfectly over the broad frequency range use for flight dynamics modeling.
Understanding the Effect of Rotor-to-Rotor Interference on CH-47D Helicopter Dynamics
Authors:   Georgia Institute of Technology, Guner Feyyaz ,   The Boeing Company, Miller David , V. J.
Published: July 2023

During the development of the Boeing CH-47D helicopter flight simulation model, test pilots reported mismatch between the flight simulator results and flight test data of the hover and low speed lateral axis handling qualities, especially for the case without the automatic flight control system. In addressing the observed mismatch, the gains of the longitudinal and lateral components of the inflow model were selected to be significantly higher than their theoretical values. In this study, a detailed understanding of the rotor-to-rotor inflow interference is pursued using a recently developed multi-rotor Pressure Potential Superposition Inflow Model (PPSIM). It is shown that couplings between the inflow gradients of individual rotors exist in a tandem rotor, which can be approximated by using higher values for the longitudinal and lateral inflow gains of individual rotors. Further, it is shown that the need for empirical tuning of aerodynamic hub moment influence factors can be eliminated by properly accounting for the rotor-to-rotor interference in the inflow model.
Bell 412 Modeling and Model Fidelity Assessment for Level-D Training Simulators
Authors:   CAE Global Engineering, Myrand-Lapierre Vincent ,   US Army CCDC AvMC, Tischler Mark ,   Delft University of Technology, Pavel Marilena ,   NRC Canada, Gubbels Bill ,   The University of Liverpool, White Mark , Nadeau-Beaulieu Michel , Stroosma Olaf
Published: July 2023

This paper presents the validation of a Level-D rotorcraft simulation framework by comparing different quantitative model fidelity metrics. The simulation framework uses a non-linear blade element rotor model to simulate the flight dynamics of rotorcrafts with accurate stability and control characteristics identified from system identification techniques. For this study, frequency-domain system identification is used to generate linear state-space 6-DoF quasi-steady models and an automated process is used to adjust the non-linear simulation framework. Regulatory authorities assess performance models for Level-D simulators by comparing time-domain simulation responses with measured aircraft responses for the same set of control inputs. Over the years, new quantitative fidelity metrics were proposed, like the Maximum Unnoticeable Added Dynamics and the Allowable Error Envelopes. This paper will focus on the blade element rotor model hover modeling process to demonstrate its application using a Bell 412 flight test data package. It will also show how this modeling approach can be used to match both Level-D requirements and the alternative fidelity metrics stated above.
eVTOL Accretion Modeling for Supporting Algorithmic Icing Detection
Authors:   Continuum Dynamics Inc., Jr. Robert , Kaufman Andrew , Quackenbush Todd
Published: July 2023

eVTOL aircraft operating within the air transportation system will undoubtably be exposed to inclement and adverse weather conditions, which may well include operation in icing conditions, whether planned or encountered inadvertently. Design compromises necessary to provide VTOL operations may make continued operation in an icing environment particularly challenging, especially for eVTOL aircraft having only limited excess power for operation of anti-icing or deicing equipment. This paper describes a research program to assess the impact of accreted icing on the performance of eVTOL aircraft, as part of a program for implementation of an Icing Detection Filter that leverages detailed knowledge of that performance impact on the distributed electrical propulsion and lift systems on the vehicle. Modeling approaches for prediction of icing accretion and the associated performance losses, particularly as they can be measured through monitoring of the onboard electrical power system, are described.
Dragonfly : Defining Environments for Rotorcraft Flight on Titan
Authors:   Johns Hopkins Applied Physics Laboratory, Lorenz Ralph
Published: July 2023

Dragonfly is an X-8 octocopter designed to explore Saturn's moon Titan, and is currently under development for launch in 2026. Titan is a uniquely favorable body for atmospheric flight, in that it has a low gravity (1/7 Earth's) and a dense atmosphere (4x Earth's) which reduce the energetic requirements for heavier-than-air flight. Dragonfly will make multiple (autonomous) flights over several years with ranges of the order of 10km to explore different sites on Titan. The key features of the Titan environment are reviewed. These include the characteristics of the landing site terrain, resembling dune fields in terrestrial deserts. Winds are generally very low, ∼ 1m/s. Stronger winds, and methane rainfall, can occur in rare rainstorms, but these are not expected at the latitude and season of Dragonfly's arrival. Brownout and triboelectric charging due to surface dust lofted by rotor downwash is possible, and these hazards and their mitigations are discussed.
Blockchain Applications for Rotorcraft Component Tracking
Authors:   Honeywell Aerospace, Taijala Taavi ,   US Army CCDC AvMC ADD-Eustis, Moffatt John , Bharadwaj Raj
Published: July 2023

In this paper we propose a hierarchical distributed database architecture (HDDA) for tracking rotorcraft configuration, usage, and health state down to the component-level. We leverage key blockchain technologies to guarantee data integrity and provide auditable and verifiable data lineage records, enabling a fleet-wide distributed architecture that scales from onboard edge nodes to enterprise server clusters. HDDA's unique design supports key rotorcraft use cases at all organizational levels, including onboard collection of rotorcraft health and usage data by edge nodes, automated record keeping to reduce maintenance burden and error for ground support personnel, fleet-wide data analysis of individual rotorcraft components to achieve longer maintenance free operating periods and improved rotorcraft health state awareness at all organizational levels. We describe the high-level design of HDDA and provide rationale for our design choices.
U.S. Army Rotary-wing Airframe Defect Trending, Modeling, and Analysis
Authors:   US Army CCDC AvMC, Peltier Jared , Chhotu Prasant
Published: July 2023

The U.S. Army monitors the structural integrity of its rotary-wing aircraft fleet through annual evaluations and reporting via the Airframe Condition Evaluation (ACE) program. ACE evaluations capture the location and character of structural defects for each aircraft, which are then available for trending and detailed analysis by engineers with the U.S. Army Combat Capabilities Development Command Aviation & Missile Center (CCDC AvMC). As analytic methods are increasingly advanced through the digital thread, CCDC AvMC has sought to improve available trending, modeling, and analysis tools beyond status quo to provide higher fidelity visuals to both aid communication with decision makers, and also to reveal structural defect trends which may not otherwise be evident. This paper will detail the development and utility of the ACE Color Mapping Application within the ACE Mapping Module and its impact on product support of U.S. Army aircraft with regard to airframe structural integrity.
Endurance Optimization of a Tandem Helicopter with Variable Speed Rotors and a Spark-Ignition Engine
Authors:   Université de Sherbrooke, Bouchard Mathieu ,   Laflamme Aéro Inc., Laflamme David , Rancourt David , Laflamme Enrick
Published: July 2023

Rotary unmanned aerial vehicles (R-UAV) are becoming commonplace as a solution for maritime surveillance activities due to their vertical take-off and landing (VTOL) capability. Extending flight duration is thus crucial; one approach is to slow down the rotors in flight, which improves their efficiency. An in-house tandem rotorcraft performance model is used to evaluate the benefits of slowed rotors in endurance flight when used in conjunction with a spark-ignition engine. The performance model is validated using experimental data from flight tests in hover and lowspeed flight. A surrogate-based optimization approach determines the flight and engine speeds required for minimal fuel consumption throughout a typical endurance mission. Payload-Endurance and Payload-Range curves for flights at various payload and fuel capacities show overall benefits. Gains up to 25% and 15% in endurance are possible for f lights at standard and maximum fuel capacity. Range is not impacted negatively and sees gains at maximum fuel capacity. The spark-ignition engine plays a beneficial role as it contributes up to 38% of fuel burn reduction.
A Vision-Based Control Method for Autonomous Landing of Vertical Flight Aircraft On a Moving Platform Without Using GPS
Authors:   Texas A&M University, Lee Bochan , Benedict Moble , Kalathil Dileep , Saj Vishnu
Published: July 2023

The paper discusses a novel vision-based estimation and control approach to enable fully autonomous tracking and landing of vertical take-off and landing (VTOL) capable unmanned aerial vehicles (UAVs) on moving platforms without relying on a GPS signal. A unique feature of the present method is that it accomplishes this task without tracking the landing pad itself; however, by utilizing a standardized visual cue installed normal to the landing pad and parallel to the pilot's/vehicle’s line of sight. A computer vision system using a single monocular camera is developed to detect the visual cue and then accurately estimate the heading of the UAV and its relative distances in all three directions to the landing pad. Through comparison with a Vicon-based motion capture system, the capability of the present vision system to measure distances in real-time within an accuracy of less than a centimeter and heading within a degree with the right visual cue, is demonstrated. A gain-scheduled proportional integral derivative (PID) control system is integrated with the vision system and then implemented on a quad-rotor-UAV dynamic model in a realistic simulation program called Gazebo. Extensive simulations are conducted to demonstrate the ability of the controller to achieve robust tracking and landing on platforms moving in arbitrary trajectories. Repeated flight tests, using both stationary and moving platforms are successfully conducted with less than 5 centimeters of landing error.
Rotor Fault Detection and Identification for a Hexacopter Based on Control and State Signals via Statistical Learning Methods
Authors:   Rensselaer Polytechnic Institute, Dutta Airin , Gandhi Farhan , Kopsaftopoulos Fotis , McKay Michael
Published: July 2023

A robust framework for fault detection and identification of rotor degradation in multicopters while effectively rejecting the effects of gusts is introduced. The rotor fault detection and identification methods employed in this study are based on excitation-response signals of the aircraft under ambient turbulence to distinguish between an aircraft response to gusts and rotor faults. A concise overview of the development of statistical time series model for healthy aircraft using the aircraft attitudes as the output and controller commands as the input is presented. This model is utilized to extract quality features for training a simple neural network to perform effective online rotor fault detection and identification in a hexacopter exceptional speed of making a decision and accuracy of fault classification. It is shown that using a statistical time series model assisted neural network employed for online monitoring is capable of rejecting gusts, sensitive to even 20% rotor degradation and achieves fault detection and identification in less than 2 s after the fault with an accuracy over 99%.
Experimental Results of Transient Variable Speed Rotor Performance for Small UAS Propulsion Scalability
Authors:   Virginia Polytechnic and State University, Edmonds Kendy ,   Kent State University, Stringer D. ,   NASA Glenn Research Center, Valco Mark
Published: July 2023

This paper is the first of two, detailing a Department of the Army funded research effort that experimentally measured the transient response of different small UAS (sUAS) rotor-motor configurations used for quadcopter applications, in order to predict the effect of scalability on the transient response. The researchers constructed an electric VTOL (eVTOL) test stand capable of measuring several aspects of electric rotor-motor performance. Experiments were conducted using seven different variable-speed rotor-motor configurations during both ramp-up and coast-down conditions between different electrical throttle settings. The results concluded that the coast-down transient was more significant than the ramp-up transient. eVTOL configurations responded differently to rotor transients compared to rotors powered by air-breathing powerplants, where rotor inertia is the predominant variable. Results show that in addition to rotational inertia, other variables influence the transient response and must be taken into account.
Restoring Practical Single Engine IFR to the Marketplace
Authors:   Bell Textron Inc., Oltheten Erik
Published: July 2023

Attempting to pick through bad weather - becoming disoriented in diminished visibility or striking a wire or obstacle at low altitude - remains one of the major causes of fatal helicopter accidents. It is more common than engine failure, more common than mechanical failures, and more common than systems failures. While some feel the answer involves more tools to enable low-flying helicopters to avoid terrain and obstacles, a better solution is to keep helicopters safely away from terrain and obstacles using instrument flight rules (IFR) when weather conditions demand. For single engine helicopters, which form the largest population of helicopters, this means finding cost effective ways to provide them with safe and practical IFR capability. IFR capability is commonplace in airplanes, even among entry-level and training aircraft. An IFR rating is typically the first rating sought after an airplane pilot receives their license. For helicopters, there is currently not a parallel culture of shifting to the safety of IFR operations when weather demands. The reasons are complex, but a significant factor affecting this culture today is that the entryl evel IFR rotorcraft is generally a twin-turbine-engine helicopter. By the time a helicopter pilot gets to this level of machine, he or she is typically well versed in the "alternate" methods of weather avoidance. Unfortunately, even IFR rated helicopter pilots tend to default to a practice of attempting to fly below the weather using visual flight rules (VFR). Increasing the availability of IFR-capable helicopters by restoring practical, low-cost IFR solutions to single engine rotorcraft is the first step in a process intended to change the rotorcraft safety culture. This paper describes a 5-year effort by associations, industry, and regulators to remove the obstacles to certifying low-cost IFR helicopters. By mid-year 2019, two single-engine helicopters were certified for IFR operations, ending an absence of more than 20 years from the marketplace, but these were newly-manufactured aircraft. The remaining challenge is to apply what has been done in order to allow cost-effective retrofits of IFR capability to the existing fleet of VFR helicopters. The hope is that, with the trail now blazed, others will follow, and we will see even more single-engine rotorcraft with IFR capability and fewer weather-related accidents.
Explainable AI: Rotorcraft Attitude Prediction
Authors:   Rowan University, Khan Hikmat ,   Federal Aviation Administration, Johnson Charles , Bouaynaya Nidhal , Rasool Ghulam , Travis Tyler , Thompson Lacey
Published: July 2023

Rotorcrafts are generally subject to a higher fatal accident rate than other segments of aviation, including commercial and general aviation. The safety improvement for rotorcrafts would directly improve the efficiency of air traffic control, since rotorcrafts operate primarily within low-level airspace; an area that is becoming increasingly complex with new entrants, such as unmanned aircraft systems and urban air mobility. The recent impact of artificial intelligence and deep learning algorithms on various aspects of our lives has led to the investigation of the application of these algorithms in the aviation domain; as it may offer a prime opportunity to enhance safety within the aviation community. In this research, we explore the efficacy, reliability, and, more importantly, the explainability of modern deep learning algorithms. We use machine learning models to predict the attitude (pitch and yaw) of rotorcrafts using video data recorded with ordinary cameras. The cameras were mounted inside the helicopter cockpit and recorded outside view through windshield continually during the flight. We train four different architectures of convolutional neural networks (CNNs), i.e., VGG16, VGG19, ResNet50, and Xception. The models achieved 90%, 91%, 88%, and 88%, respectively, average attitude prediction accuracy on the test video dataset. Furthermore, we use gradient class activation maps (grad-CAM) to ascertain the features and regions of the image that influenced the model to make a specific prediction. We show that CNNs learn to focus on similar features as human operators (pilots), i.e., the natural horizon curve. Our findings demonstrate the feasibility of using deep learning models for attitude prediction from f light videos recorded using ordinary inexpensive cameras. The proposed video analytics framework provides a cost-effective means to supplement traditional Flight Data Recorders (FDR); a technology that is often beyond the financial reach of most general aviation rotorcraft operators.
Status and Way Forward on Rotorcraft Lightning Protection
Authors:   Airbus Helicopters, Zehar Sonia , Meyer Marc , Tagliana Bernard
Published: July 2023

This paper provides an overview of the state of art on the lightning regulation and the means of compliance for lightning certification, based on both the simulation technics and the testing methods. Usual lightning protection solutions at helicopter level to fulfill lightning requirements are discussed, as well as advanced approaches used by Airbus Helicopters to minimize the weight penalty of the lightning protection, especially by a large use of the simulation for the optimization of both the indirect effects (LIE) and the lightning direct effects (LDE).

Some perspectives are highlighted concerning the development of new lightning protection devices to withstand the higher induced currents coupled on equipment items installed in full composite airframe helicopters (H/C), and how the lightning may be avoided on future platforms like the emergent flying urban taxis.
Determining TH-1H Tailboom Loads from Measured Strain Gage Data
Authors:   Mercer Engineering Research Center, Taylor Dr. , Gibson Ms. , Mason Ms.
Published: July 2023

This work develops tailboom aerodynamic loading for a TH-1H helicopter in hover by integrating a finite element model (FEM) and in-service strain time histories in accordance with structural mechanics and aerodynamics principles. The FEM is a whole aircraft model used to establish stress spectra at critical aircraft components for fatigue and fracture analyses from main rotor and tail rotor forces. The in-service time histories are the responses from sixteen uniaxial strain gages attached to the tailboom primary longerons and the corresponding structure inside the main cabin. Five separate loading modalities are used as FEM static load cases. Published experimental drag coefficients are used to develop two aerodynamic pressure load distributions for the tailboom as well as separate left and right elevator pressure loads. The fifth case is a lateral tail rotor force. Weighting factors are determined for these five modalities so that the weighted sums of the FEM strains best-fits the measured strains at the sixteen gage locations. This fitting process is executed for each time step of each strain gage in a given hover regime, as well as for the average gage values for the duration of the regime. Weighting factors are evaluated for admissibility (i.e. non-negative values, bounded magnitudes that do not produce unrealistically high stresses). The results are compared against the measured strains. The mechanics of the tailboom structure is also evaluated with respect to strains, longeron loads, and netsection bending moments. The findings highlight that the longerons (where the strain is measured) account for approximately two-thirds of the tail boom bending moments; the external skins and stiffeners provide the balance of the moments. Two load modality combinations emerged as best-fits: tail boom aerodynamic pressure loading plus tail rotor force, and elevator pressure loading plus tail rotor force. Both show varying levels of fidelity to the measured data, which suggests that additional load modalities should be considered, and that additional instrumentation of the skins should be implemented for future strain surveys.
Integration of VTOL Air-taxis into an Existing Infrastructure with the Use of the Model-Based System Engineering (MBSE) Concept CUBE
Authors:   FEV Europe GmbH, Jäckel Nicolas ,   FEV Consulting GmbH, Fischer Maximilian ,   Institute for Combustion Engines, Andert Jakob , Grotenrath Malte , Orth Philipp , Schaller Robert , Granrath Christian
Published: July 2023

One major problem of big cities is the congested traffic situation and the noise pollution generated by the traffic participants, i.e., cars, busses, and trams. Those ground-bound transport systems are already reaching their limits. The use of aerial taxi services has the potential to use the third, vertical dimension. Vertical take-off and landing systems, shortened to VTOL systems, possibly autonomous and electrified, with low noise emission and little ground space requirements are preferred. Applying an MBSE-based approach like our methodology called 'Compositional Unified system-Based Engineering', in short CUBE, enables to control the complexity of the challenge to develop appropriate VTOLs. This methodology has already proven itself in the automotive industry and its system development processes. In this paper the CUBE methodology will be transferred to the aerospace system development process to demonstrate its general usability. The fully systematical and model-based description of the System of Systems (SoS, meaning urban infrastructure here) is used to condense the requirements for the System of Interest (SoI, meaning VTOL) regarding many possibilities and limitations. This concept is a promising approach to create system-based and model-based specifications of requirements for the VTOL systems, which later shall operate seamlessly as part of the SoS.
A Systems Engineering Approach for Enabling Research and Development in the Vertical Lift Autonomy Flight Sciences Domain
Authors:   National Research Council of Canada, Alexander Marc ,   The Boeing Company, Spano Mark , Gowanlock Derek , Gubbels Arthur , Dones Fernando , Rossi Glenn
Published: July 2023

The objective of the joint National Research Council of Canada (NRC) and The Boeing Company Technology Development Program (TDP) entitled 'Canadian Vertical Lift Autonomy Demonstration' (CVLAD) is to evaluate automated and supervised autonomous flight systems on NRC Bell 412 Advanced Systems Research Aircraft (ASRA) and Royal Canadian Air Force Boeing CH-147F Chinook demonstrators. Boeing technologies such as Degraded Visual Environment Pilotage System and Advanced Vehicle Management System form the foundation of an autonomy solution that aims to satisfy Royal Canadian Air Force, US Army, and other Armed Service branch end-use objectives for force multiplication, tactical advantage, pilot assistance, reduced crew operations, and enhanced fleet productivity. The Boeing Company engaged NRC under a Cooperative Research Agreement since 2016 as part of a number of strategies to upgrade Medium-Heavy Lift H-47 Chinook capabilities prior to long-term aircraft replacement in the 2030 to 2060 timeframe. A recent achievement of the CVLAD TDP by its Boeing Phantom Works, Boeing Chinook Program, Aurora Flight Sciences, and NRC Flight Research Laboratory team was the development of Automated Flight Guidance methods addressing system safety and performance. Design and evaluation activities occurred in Boeing Software-/Hardware in-loop facilities as well as on the NRC Bell 412 ASRA. The CVLAD team is using a blend of traditional Systems Engineering 'V-Shaped' Life Cycle Model, System of Systems, and Model-Based processes to develop a cyber-physical system that aims to meet end-user concept of operations and requirements. Significant benefits of virtual development tools such as component-vehicle digital twins and surrogate inflight simulation facilities are achieved as they promote effective collaboration, efficient design, and relevant verification/validation methodologies. Business models can be made more robust by phasing the introduction of technology where effective automation provides users with near-term benefits, while providing a foundation for safe, reliable, and trusted autonomous capabilities for long-term production.
Experimental and Numerical Investigation of Interaction Between Rotor and Wing at High Advance Ratio
Authors:   Japan Aerospace Exploration Agency (JAXA), Tanabe Yasutada ,   SUBARU Co., Hayashi Hirotaka , Kobiki Noboru , Sugawara Hideaki , Kobayashi Wataru , Satou Ryosuke
Published: July 2023

In this paper, an experimental and numerical study of a rotor interacting with wing of three different aspect ratios at an advance ratio of 0.5 is described. Those three wings have the equal area and fixed at an angle of attack of 8 degrees. One wing is installed at 3 different vertical positions and three different horizontal locations to investigate the influence of the wing position on the interaction. The calibration and correction process of the measurement is described, and the results are compared to pre-test CFD simulations. Numerical simulations based on simplified rotor and wing-body models have been carried out ahead of the wind-tunnel testing. Due to the existence of rotor-test-stand and the rotorhub which are not included in the CFD simulations, the measured aerodynamic performance deviated from the CFD results remarkably. By applying angle-of-attack and drag offset corrections which remove the influence of the rotortest-stand, the wing performance is found in good agreement with the CFD results. Also, applying hub-correction which is based on measured hub-only aerodynamic force components, and the angle-of-attack correction, the corrected isolated rotor performance in high advance ratio agrees satisfactorily with the CFD data. It is found that due to the rotor/wing interaction, the overall lift-to-effective drag ratios decrease about 12% at the advance ratio of 0.5.
MH-60 Full Scale Test Rig Loads Development and Analysis
Authors:   MERC, McGinty Robert ,   DST Group, Vine John ,   NAVAIR, Liebschutz Dan ,   SAIC, Conjelko Philip , Brenna Jeffery
Published: July 2023

Mercer Engineering Research Center (MERC) is supporting Naval Air Systems Command (NAVAIR) in the determination of external airframe loading requirements and test rig design support for an MH-60 full scale fatigue test demonstrator project being conducted in collaboration with the Australian Defence Science and Technology Group (DST Group). The analyses included determination of loads for quasistatic and vibratory flight conditions, sensitivity of the structural response to the loads, displacements at actuators across the MH-60R usage spectrum, and feasibility of driving aircraft vibrations at frequencies lower than those measured in flight - specifically, obtaining vibration levels measured at 17.2 Hz by imposing forces at only 2.15 Hz. The studies also addressed the minimum number and locations of actuators required for static and vibratory loading.