bluuebunny/crossref_metadata_2025 huggingface dataset:
Strategy for Incorporating DAFIF into a Modern Military Cockpit Interface
Authors:   The Boeing Company, Smith Andrew
Published: October 2024

The Digital Aeronautical Flight Information File (DAFIF) is a database version of aeronautical information provided to the United States Department of Defense by the National Geospatial Intelligence Agency. This paper describes a practical strategy to incorporate DAFIF into a modern cockpit graphical user interface. This strategy is based on using Federal Aviation Administration (FAA) Aeronautical Navigation Products as reference for presenting aeronautical information. The FAA products are then used in pilot task analysis. This provides a foundation for identifying concepts for incorporating DAFIF into a next generation cockpit interface in a manner that aids military pilots in these tasks. This paper provides four simple examples of implementing this strategy for a theoretical cockpit interface. Each example is based on a different type of FAA Aeronautical Navigation Product. This strategy identifies many various concepts that could be incorporated and helps prioritize them. Keeping a pilot-centered approach ensure the concepts continue to increase situational awareness and usability.
Effects of 2/rev Trailing Edge Flap Input on Helicopter Vibrations for Concurrent Vibration and Noise Reduction
Authors:   Institute of Flightmechanics and Control, Steinwandel Alexander , Fichter Walter
Published: October 2024

For the simultaneous operation of two independent active rotor controllers, one with the goal of reducing helicopter vibration, the other aiming at BVI noise reduction, the interactions between the two control tasks need to be considered in order to achieve an optimal operation. In this work, the direct interactions between BVI noise reduction using 2/rev trailing edge flap inputs and vibration reduction are investigated in the form of effects of 2/rev trailing edge flap input on 4/rev helicopter vibration. The purpose of this investigation is to find models describing this kind of interaction in order to determine an optimal way for simultaneous operation of independent controllers for the reduction of BVI noise and helicopter vibration. To this end, flight data consisting of two flight tests with a full-scale EC145, the rotor of which was equipped with trailing edge flaps, is examined. From one part of the flight data a model, based on a transfer matrix approach, is derived, the other part of the flight data is used for validation. Finally the robustness of the model is examined by looking at flight data at different flight conditions.
Overview of RCAS Capabilities, Validations, and Rotorcraft Applications
Authors:   Advanced Rotorcraft Technology Inc., Saberi Hossein ,   US Army Aviation Development Directorate - AFDD, Yeo Hyeonsoo , Hasbun Matthew , Hong JinYoung , Ormiston Robert
Published: October 2024

This paper presents an overview of the Rotorcraft Comprehensive Analysis System (RCAS) capabilities, recent enhancements, and validations and also demonstrates RCAS' application to practical rotorcraft problems. More than 10 years have passed since a similar paper was presented. During this time RCAS has been continually enhanced and there have been several significant developments. This paper summarizes these developments, which include new structural elements and improvement of exiting ones, addition of new wake and airloads options, addition of coupling with external wake modules, expansion of coupling with CFD modules, and development of a graphical user interface. This paper surveys and adds to the body of RCAS validation, which has greatly expanded since the last paper. RCAS validations now include detailed work on RCAS' vortex wake models, blade element momentum inflow models, and RCAS/CFD coupling capabilities to name a few. By summarizing RCAS' capabilities, recent developments, and validations, while also demonstrating RCAS applications, this paper provides the rotorcraft technical community with an up-to-date and consolidated resource on the state of RCAS comprehensive analysis.
Flight Evaluation of Variation in Rotor RPM on Low Speed Handling Characteristics of Helicopter
Authors:   Hindustan Aeronautics Limited, Tajar Abdul , Kumar M. , Rao D.S.D. , Muthu R.
Published: October 2024

This paper describes multi fold advantages of increasing the Rotor RPM to improve low speed handling of helicopters in high altitude operations, where-in the availability of engine power, control margin and air density ratio play an important role. The primary aim of this work was to reduce the tail rotor collective requirement in hover, sideward flight, spot turns and in take-off and landing at high altitudes. The increase in rotor RPM was also proven beneficial for low speed handling at low altitude with high all up weight. Simulations were carried out for different all up weights and altitudes to ascertain the effect of variation of rotor RPM on tail rotor collective, main rotor collective and torque requirement in hover and sideward flight. Effect of increased rotor RPM on main rotor blade loads (mainly flap and lag) was also examined through a six DOF helicopter simulation program. Based on the results obtained from simulations, comprehensive flight testing was carried out to confirm simulation results. Flight test data showed that the increase in rotor RPM reduces tail rotor collective requirement. The reduction in main rotor collective and torque requirement (per engine) with increased rotor RPM was also observed. Enhancement in wind handling capability over the critical azimuth and spot turn capability was established. Fatigue loads marginally reduced with higher RPM than the nominal RPM. Cockpit vibration levels were similar and change was not perceptible with higher rotor RPM. Vibration on tail drive shaft and tail rotor actuator with higher rotor RPM, reduced during hover, left sideward flight and spot turns. The trends were independent of all up weight and altitude. The effect of increased rotor RPM on Engine, Transmission, Flight controls and Maintenance was also assessed during flight testing.
The U.S. ARMY's CH-54 Skycrane Helicopter: History and Contributions
Authors:   US ARMY (Retired), Fardink Paul
Published: October 2024

The U.S. ARMY officially retired the CH-54 "Skycrane" from inventory in the early 1990s. This paper examines the unique history and numerous contributions of the CH-54, supported by interviews from several people directly responsible for its development, testing, and utilization. The acquisition and fielding are examined, including deployment to Vietnam. The Crane's dimensional and performance specifications are reviewed, as well as its capability for precision placement or extraction of loads from untenable areas. The Crane set several performance records and the techniques of one such record-breaking flight are also discussed. The Skycrane left active duty in 1979 and all helicopters were transferred to National Guard units. Ten years later, the final CH-54 distribution within the National Guard structure is examined as well as the final disposition of the aircraft. The reasons for the Crane's retirement are addressed, including a summary of cost savings from retrieved aircraft during the Vietnam War. Finally, the utilization of the remaining airframes within civilian aviation is examined.
Performance Qualification of an On-Board Model-Based Diagnostic System for Fatigue Crack Monitoring
Authors:   Politecnico di Milano, Sbarufatti Claudio , Manes Andrea , Giglio Marco
Published: October 2024

Very little success has been reported in the literature in developing diagnostic systems trained on simulated data that can accurately describe the real situation. Furthermore, no studies attempting automated structural health monitoring (SHM) system performance qualification are available. A diagnostic algorithm based on an artificial neural network and trained with finite element simulated strains has been verified during repeated fatigue crack growth tests on metallic helicopter fuselage panels. Strain measures from a network of fiber Bragg gratings are provided as input to the diagnostic system, allowing fatigue crack damage identification. Anomaly detection performances have been evaluated with reference to the recent Aerospace Recommended Practice (ARP-6461) and the Recommended Practice for a Demonstration of Nondestructive Evaluation Reliability on Aircraft Production Parts, providing a SHM system qualification in terms of minimum detectable crack length, based on reliability-confidence curves. In particular, repeated fatigue crack growth tests on metallic aerospace panels allowed the estimation of the probability of detection as a function of crack length. Furthermore, a numerical model of the monitored structure has been used for the generation of virtual specimens, thus enabling the model-assisted probability of detection assessment.
Interactive Work Instructions for Bell 525 Relentless
Authors:   Bell Helicopter Textron Inc., Grenier Isabelle
Published: October 2024

The manufacturing industry has put into practice a methodology that embraces Design for Manufacturing and Globalization. Competition in the global manufacturing industry demands greater forethought in new product development. Products must transition through the development lifecycle faster, provide flexibility to transfer manufacturing operations to other countries, facilitate cost reduction and augment strategic market objectives. To achieve these goals at Bell Helicopter, the new Bell 525 Relentless has made extensive use of Engineering Digital Product Definition (DPD) and Interactive Work Instructions (IWI). A cultural change achieved the end result of a design that contains a new product structure capable of leveraging global technology resources, with creative delivery of work instructions for manufacturing.
Effects of Uncertainty on Slung Load Divergence Speed Determination
Authors:   Georgia Institute of Technology, Liberi Brandon ,   University of Florida, Ton Chau , Pirau Sorin , Komerath Narayanan
Published: October 2024

Azimuth-resolved 6-DOF loads data are now available on objects of arbitrary shape and attitude as discrete series. Divergence speeds of single-point slung loads are determined using simulation from these airloads, for flight at constant speed. The effects of various types of uncertainty on the divergence speed are studied. Scale-model divergence speeds for a cylinder of L/D 1, and a porous box are obtained. Three types of uncertainties are examined: measured or predicted air loads, poorly-resolved load variations, and gusts. Results show that typical uncertainties in wind tunnel data from continuous-rotation testing have little effect on divergence speed prediction. Poorly-resolved data cause significant uncertainty in the path towards divergence, but not the actual divergence speed, for some shapes. A robust control approach shows that the effects of gusts and maneuvers can be alleviated to some extent by flight control, so that safe flight near predicted divergence speed appears to be feasible.
A Comprehensive Pilot Model for Voluntary/Involuntary Action in Rotorcraft-Pilot Coupling
Authors:   The University of Liverpool, Jump Michael ,   Politecnico di Torino, Marguerettaz Paolo ,   Politecnico di Milano, Masarati Pierangelo , Lu Linghai , Guglieri Giorgio , Muscarello Vincenzo , Quaranta Giuseppe
Published: October 2024

This work proposes a helicopter pilot model identified from experimental results obtained in piloted simulation flight tests. The tests were originally designed to verify predicted unstable pilot-vehicle systems. The results have been further analyzed using methods for the detection of pilot induced oscillation that are available from the literature. The results show that a pilot-assisted oscillation event occurring in one configuration is characterized by a change of biomechanical properties of the pilot. It is conjectured that such change is triggered by a change in the task of the pilot induced by the specific maneuver that is requested of the pilots in the tests.
Development and Testing of a Ground Based Health and Maintenance Reasoner
Authors:   Sikorsky Aircraft Corporation, Cotter James ,   Army ADD-AATD, Baker Treven , Davis Mark
Published: October 2024

The Sikorsky Aircraft Corporation and the U.S. Army Aviation Development Directorate - Aviation Applied Technology Directorate have jointly sponsored the Capability-Based Operations and Sustainment Technology-Aviation (COST-A) program. The objective of COST-A has been to develop and demonstrate an integrated set of high-value diagnostics, prognostics, and system health management technologies for six different rotorcraft systems with a focus on reduced maintenance burden without sacrificing safety. This paper focuses on the COST-A Ground-Based System (GBS), which was developed to demonstrate an environment for translating the results from new COST-A technologies into actionable information to be provided to personnel in multiple maintenance roles. The approach was to build upon existing Army maintenance practices and tools used for aircraft that are currently equipped with health monitoring systems such as the Integrated Vehicle Health Management System (IVHMS) deployed on the UH-60 BLACK HAWK, while demonstrating the benefit of fusing onboard system data with historical fleet data and providing maintenance planning tools. The overall architecture and role of the GBS are described along with highlights of new GBS capabilities developed and demonstrated under COST-A.
V-22 Osprey Maintenance Cost Savings using SAFE for Fatigue Life Calculations
Authors:   Bell Helicopter, Kelly Stacey , Lloyd John
Published: October 2024

The V-22 SAFE (Structural Appraisal of Fatigue Effects) is a software program for the V-22 Osprey tiltrotor aircraft that calculates fatigue damage for serialized components based on the aircraft's actual usage instead of a pre-defined design spectrum. SAFE allows life limited aircraft components to remain on the aircraft beyond the initially defined fatigue life if the aircraft was flown less aggressively than the design spectrum. Although fatigue lives for the various components are determined with the same design usage spectrum for the aircraft, different maneuvers within that design spectrum will drive the fatigue damage assessment for different components. For example, a component in the rotor system may be sensitive to high g maneuvers in helicopter mode, while the airframe is more sensitive to hard landings and taxi conditions. Aircraft that fly a milder usage will incur a lower operating cost since components are not replaced as often. With SAFE in operation, a few components will be replaced early if severe loadings are encountered. Trending, however, indicates that fleet aircraft generally operate below the loading thresholds of the design usage spectrum. Only flight test aircraft that are often flown at the edge of the envelope see high loadings more frequently than the design usage spectrum. With current fleet usage trends, a cost assessment of individual components by SAFE analysis shows that savings can be significant.
Modeling CT7/T700 Maintenance Costs
Authors:   GE Aviation, Martin John ,   US Army, Alexander Gordon , Duane Greg , Hlavac Bennett
Published: October 2024

Turboshaft engines are a significant contributor to rotary wing aircraft life cycle costs, typically over 40%. Maintenance costs are the largest portion of the life cycle cost of an engine, as compared to development, acquisition, and fuel costs. Understanding these costs is important to guiding engine design and maintenance practice decisions. This paper describes the development and use of deterministic and probabilistic simulation model of the CT7 commercial turboshaft engine and its application to US Army maintenance of a military version of the engine. The model is used on several commercial aircraft to quantify engine maintenance costs ($/EFH), time on wing (TOW), field maintenance labor hours, and required sparing. The application of this model to the US Army T700-GE-701D engine is described. Maintenance practices are analyzed to optimize readiness at best value. Engine design tradeoffs are evaluated based on overall Life Cycle Cost. The influence of operating environments is also addressed, such as accounting for the impact of harsh environments. Recommendations to reduce maintenance cost per hour are described.
Adaptable Gas Turbine Blade Concept Study
Authors:   US Army, Murugan Muthuvel , Booth David , Ghoshal Anindya , Thurman Douglas , Kerner Kevin
Published: October 2024

Articulating the pitch angle of a turbine blade can improve performance by maintaining optimum design incidence and thus reduce the probability of flow separation and thermal stresses developed due to aerothermal loads for variable speed gas turbine engine applications. Potential benefits to Army Aviation are highly efficient (aerodynamically) turbine blades, possible reduction of the need for active blade cooling and thermal barrier coatings, increased fuel efficiency, power density, and the ability to fly faster and longer. The goal of this effort is to assess the benefit and feasibility of an adaptable variable pitch turbine blade for maintaining attached flow and optimal thermal design for a gas turbine engine. A technology concept study has been conducted to enable a viable adaptable turbine rotor blade that can enhance the performance and efficiency of future aircraft gas turbine engines. A typical aircraft t turbine blade is used for this technology concept study. An adaptable turbine rotor blade, if made feasible, can lead to a leap ahead technology innovation in improving part-load efficiency of gas turbine engines.
Thermal Behavior of Aerospace Spur Gears in Normal and Loss-of-Lubrication Conditions
Authors:   NASA, Handschuh Robert
Published: October 2024

Testing of instrumented spur gears operating at aerospace rotorcraft conditions was conducted. The instrumented gears were operated in a normal and in a loss-of-lubrication environment. Thermocouples were utilized to measure the temperature at various locations on the test gears and a test utilized a full-field, high-speed infrared thermal imaging system. Data from thermocouples was recorded during all testing at 1 Hz. One test had the gears shrouded and a second test was run without the shrouds to permit the infrared thermal imaging system to take date during loss-of-lubrication operation. Both tests using instrumented spur gears were run in normal and loss-of-lubrication conditions. Also the result from four other loss-of-lubrication tests will be presented. In these tests two different torque levels were used while operating at the same rotational speed (10000 rpm).
Fatigue Load Spectra for a Conventional Military Rotorcraft
Authors:   US Army Aviation Engineering Directorate, Benton Robert
Published: October 2024

This paper extends the author's prior effort to provide a framework for fair, early, and meaningful assessment of rotorcraft fatigue durability. In this paper a comprehensive set of fatigue load spectra have been characterized for a conventional military rotorcraft and provided for potential future use by the reader. The author's method of mixed-Weibull parameterization has been improved over the prior method. Mixed-Weibull parameterization allows grouping of various sets of load paths as well as analytical comparison of the distributions. This paper includes an assessment of sensitivity to changes in airspeed limitations at altitude, as well as an assessment of sensitivity to human influence during mixed-Weibull parameterization. Once standardized mission spectra are established, they will prove useful in fatigue life specification verification, preliminary and detailed design, and structural test planning.
A Probabilistic Approach for Reliability Quantification of Propulsion Materials
Authors:   Department of Army, Shiao Michael , Chen Tzikang , Ghoshal Anindya
Published: October 2024

A new probabilistic approach to assess the reliability of brittle materials for high temperature engine components was developed. The probability of failure due the fracture of a randomly oriented damage inherent from manufacturing process was determined by a hybrid probabilistic method (HPM) for computational efficiency and accuracy. The random variables considered by this approach for overall component failure probability include fracture toughness, loads, geometric factor, initial damage size, damage growth rate, damage orientation and damage occurrence in a unit volume. HPM consists of four modules: (1) an efficient reliability algorithm, (2) a surrogate model, (3) a bi-linear interpolation scheme and (4) a random simulation method. Seven cases with various types of loads and failure mechanisms were performed by both the hybrid approach and traditional Monte Carlo simulations (MCS). For all the cases studied, the results by HPM compare very well with that by traditional MCS. HPM also shows great efficiency over traditional Monte Carlo simulations. In addition, this new probabilistic framework allows further improvement in computational efficiency by exploring other efficient simulation methods.
A Multiscale Bondline Damage Characterization and Hybrid Analysis Approach for Adhesively Bonded Composite Structures
Authors:   Global Engineering and Materials Inc., Fang Eugene ,   Carnegie Mellon University, Zhang Jessica ,   Naval Air Warefare Center (PAX), Rahman Anisur , Lua Jim , Phan Nam
Published: October 2024

Adhesively bonded composite structures have been used extensively in both DoD and commercial industries. Despite many attractive features of a bonded composite structure, integrity and durability of adhesively bonded composite structures are the primary concerns due to their known sensitivity to environmental conditions and the presence of bondline defects associated with the fabrication and processing of a bonded composite structure. In order to reduce the testing matrix in characterization of properties of a bondline for the residual strength and life prediction of its bonded composite structure, a multiscale approach is developed based on an automatic generation of a representative unit cell of a heterogeneous bondline interface including voids and inclusions. Equivalent cohesive properties are extracted from a nonlinear finite element analysis for a unit cell with variations in size and geometric distribution of voids and inclusions within the bondline. The impact of a bondline quality on a global structural response is explored using a bonded I-beam with an initial delamination flaw subject to 4-point bending.
Integration of 3D Scan Data into the Finite Element Analysis Workflow for Simulation of Rotorcraft Components
Authors:   Bell Helicopter, Knoll Jonathan , Nissen Jeffrey
Published: October 2024

A process for integrating 3D scan data into the finite element analysis (FEA) workflow is presented. The process was developed to utilize CAD and/or scan-based geometry to create a 3D Finite Element model for structural analysis. Three significant phases of the process include surface acquisition, geometric refinement, and FEA evaluation. The scan-based process provides a cost effective method to capture the surface geometry of physical components and permits a digital representation of the article to be created for analysis purposes. It is shown that the role of alignment, deviation checking, and prior analysis are significant factors in efficiently developing models for FEA. The application of scan-based FEA was highly effective in simulating component repairs, weldments, and predicting mechanical test behavior. Results from these applications were substantiated by digital image correlation and strain gauge data, showing excellent correlation between 3-10%. When comparing scan-based FEA results it was found that accounting for paint thickness can have a significant effect on the accuracy of the results. With a successful scan-based FEA approach developed, numerous applications of the process resulted in reduced scrap rate, supported safety of flight testing, and ensured continued on-time delivery of aircraft.
Multi-Body Peridynamics for Failure Prediction in Rotating Thick Composites
Authors:   University of Arizona, Madenci Erdogan ,   Naval Air Systems Command (NAVAIR), Phan Nam , Barut Atila
Published: October 2024

This study presents the integration of the nonlocal peridynamic theory with the well-established rigid multibody dynamics algorithms to predict material and structural failure modes simultaneously in flexible multibody dynamic systems. Although the existing structural dynamics analysis methods provide accurate dynamic simulation and deformation predictions, they lack the capability to predict material and structural failure initiation and failure modes simultaneously necessary to ensure durability and reliability. This analysis accounts for large elastic deformations coupled with dynamic motion loads without the need of post-processing for failure prediction. The accuracy of this approach is verified against the solutions already available in the literature. It specifically demonstrates damage initiation and growth in rotating composite blades.
A DAVBA Approach for Complex VTOL Aircraft Development
Authors:   Georgia Institute of Technology, Schrage Daniel ,   Dassault Systems, Van Alex
Published: October 2024

As aircraft systems become more complex the need to integrate software and hardware at different levels of abstraction becomes more important. For complex civil aircraft USA and Europe have reached a consensus in "Guidelines for Development of Civil Aircraft and Systems Development" in SAE ARP 4754A/ED-79. This document discusses the development of aircraft systems taking into account the overall aircraft operating environment and functions. This includes validation of requirements and verification of the design implementation for certification and product assurance. It provides practices for showing compliance with the regulations and serves to assist a company in developing and meeting its own internal standards by considering the guidelines in it. It focuses on the need for aircraft and system (both hardware and software) functional hazard assessment and safety analysis early in the complex system development process. For military aircraft system development, airworthiness qualification and safety assessment are often conducted too late in the development process. This results in the airworthiness process and the DOD acquisition process being incompatible for the acquisition of complex systems. The Department of Defense (DoD) needs to focus on the value a thing has over its useful life. This change will allow DOD to compete differing solutions and get the best value. The key to Value Based Acquisition (VBA) at the program level is the development of a value model that embodies key system design features, such as weight, manufacturing cost, reliability, and the like, as well as key acquisition concerns, such as cost and schedule. Once a quantitative value model has been defined, it can become the basis for contracting. This paper will propose how a combination of the Development Assurance (DA) civil aircraft approach in SAE ARP 4754A/ED-79 and a VBA approach can be combined for a DAVBA Approach for military planned VTOL Aircraft Development, such as Future Vertical Lift (FVL). An example of how the approach can be developed for a FVL baseline, the UH-60M Black Hawk Helicopter, will be presented.
Experimental Investigation of Rotorcraft Outwash in Ground Effect
Authors:   US Army Aeroflightdynamics Directorate, Tanner Philip ,   NASA Langley Research Center, Jenkins Luther , Overmeyer Austin , Yao Chung-Sheng , Bartram Scott
Published: October 2024

The wake characteristics of a rotorcraft are affected by the proximity of a rotor to the ground surface, especially during hover. Ground effect is encountered when the rotor disk is within a distance of a few rotor radii above the ground surface and results in an increase in thrust for a given power relative to that same power condition with the rotor out of ground effect. Although this phenomenon has been highly documented and observed since the beginning of the helicopter age, there is still a relatively little amount of flowfield data existing to help understand its features. Joint Army and NASA testing was conducted at NASA Langley Research Center using a powered rotorcraft model in hover at various rotor heights and thrust conditions in order to contribute to the complete outwash data set. The measured data included outwash velocities and directions, rotor loads, fuselage loads, and ground pressures. The researchers observed a linear relationship between rotor height and percent download on the fuselage, peak mean outwash velocities occurring at radial stations between 1.7 and 1.8 r/R regardless of rotor height, and the measurement azimuthal dependence of the outwash profile for a model incorporating a fuselage. Comparisons to phase-locked PIV data showed similar contours but a more contracted wake boundary for the PIV data. This paper describes the test setup and presents some of the averaged results.
Development Of A Generic Test For Transient Recovery Handling From Helicopter Active Inceptor System Failures To A Near-Zero Control Force Condition
Authors:   DLR, Müllhäuser Mario ,   ETPS, Barnett Miles
Published: October 2024

In the event of an aircraft's cyclic Active Inceptor System (AIS) failure, causing sudden loss of actively generated control forces, its flight control mechanical characteristics (FCMC) would degrade to the system's inherent, near-zero force characteristics (the isotonic mode). In this degraded mode the pilot would have to recover the control of the aircraft and then land the aircraft safely. In order to mitigate the risks associated with this failure and to optimise the inherent FCMC and augmentation laws for improved handling qualities (HQ), a standardised and generic test that incorporated all influencing worst case flight and control parameters needed to be defined. The data from simulator evaluations were analysed and it was concluded that the most influencing parameters on the severity of transient response and recovery were the steady inceptor force and the pilot's level of attentiveness at the point of failure. Using the results of this analysis, a generic test is presented for isotonic AIS failure mode evaluation.
Instrumented Deck Landing Cueing in Unmanned Aircraft Systems
Authors:   Hoffman Engineering LLC, Ferrier Bernard ,   Naval Air Systems Command (NAVAIR), Ernst Robert ,   Wyle Laboratories Inc., Sehgal Ajay
Published: October 2024

The primary difference in naval helicopter launch and recovery methodologies between manned and Unmanned Aircraft Systems is centered on pilot decision making logic. This logic is heavily influenced by, amongst other parameters, visual cueing. This paper focuses on the investigation converting manned recovery cueing to digital definitions and the corresponding instrumentation development. The deck condition definitions normally estimated empirically using standard rating scales, are replaced by instrumentation measuring the status of the deck prior to touch-down. Discussion describing one of the new deck measuring devices designed to replace piloted cueing, is provided. Theory, previous simulation studies and current at-sea testing along with data results, are discussed. The interface of the deck measuring device into the next version of the Fire Scout UAS system is provided.
A Control Architecture For Fast And Precise Autonomous Landing Of A VTOL UAV Onto An Oscillating Platform
Authors:   Rensselaer Polytechnic Institute, Hu Botao , Lu Lu , Mishra Sandipan
Published: October 2024

In this paper, the problem of landing an unmanned aerial vehicle (UAV) on a platform with unknown oscillating motion is investigated. A control architecture that enables fast, safe and precise landing process is proposed. This control architecture consists of three modules: a tracking control module, a trajectory generation module and a vision-based motion estimation module. For the tracking control module, an Adaptive Robust Controller (ARC) is used to robustly adapt to the changes in thrust due to ground effect. In the trajectory generation module, a time optimal reference trajectory is generated to follow the platform motion. In the motion estimation module, the motion of the moving platform and the UAV is estimated based on only relative distance measurement and acceleration measurement. Comparative simulation and experimental results are presented to validate the effectiveness of the proposed control architecture.
System Identification and Controller Optimization of a Quadrotor UAV
Authors:   University of Cincinnati, Wei Wei ,   AMRDEC - US ARMY, Tischler Mark , Cohen Kelly
Published: October 2024

Multi-rotor aircraft, such as the quadrotor, are increasingly popular for small-scaled VTOL UAVs. In order to develop an effective control system through simulation techniques, obtaining an accurate dynamic model of a given quadrotor is crucial. Moreover, given the anticipated stringent safety requirements, fault tolerance will be a crucial component of UAV certification. Accurate dynamic modeling and control of this class of UAV is an enabling technology and crucial for future commercial applications. In this paper, the extraction of the bare-airframe dynamic model of a quadrotor UAV in hover condition using frequency-domain system identification techniques and its simulation is presented. The model is verified in the time-domain using dissimilar flight test data not used in the identification. The dynamic model and onboard PID controller are simulated and verified in Simulink®. Then, the controller is optimized to achieve significantly improved performance in both simulation analysis and flight tests. This paper presents details of the quadrotor system design, model extraction techniques, dynamic model verifications, controller optimization and flight test results.
Experimental and Computational Investigation of a Small-Scale Vertical Axis Wind Turbine with Dynamic Blade Pitching
Authors:   Texas A&M University, Benedict Moble ,   Science and Technology Corporation, Lakshminarayan Vinod ,   University of Maryland, Garber Jeremy , Chopra Inderjit
Published: October 2024

This paper describes the systematic performance measurements and computational (CFD) studies conducted to investigate the performance of a small-scale dynamic-pitch vertical axis wind turbine (VAWT). The VAWT prototype was built and tested in a wind tunnel to understand the role of blade-pitch kinematics and flow curvature effects on turbine aerodynamic efficiency. The three parameters investigated in the experimental study were blade pitching amplitude (symmetric pitching), asymmetry in pitch kinematics between frontal and rear halves, and blade chord (or chord/radius ratio). Even though the optimal pitch amplitude is dependent on the tip speed ratio (TSR), moderate pitch amplitudes (± 20° ) had the highest overall efficiency for the symmetric pitch cases. The tip speed ratio corresponding to the maximum CP decreased with increasing pitch amplitudes. The TSR corresponding to maximum CP for 20° pitch amplitude was around 1.4, while the optimal TSR for the 40° case was around 0.7. Because of the differences in the flow velocities in the front and rear halves, for maximizing power extraction, the pitch angles required in the front is significantly higher than that in the rear. The optimal performance of the turbine occurred at a phasing of 0°. However, the performance was observed to be forgiving for small changes in phasing (<10°) in the positive direction (phase-lead), however, not in the negative direction. Increasing the chord/radius from 0.19 to 0.25 caused significant improvements in turbine efficiency especially at higher pitch amplitudes because of the flow curvature effects. A CFD model was developed and extensively validated with the present experimental data. The validated CFD model was used to understand the effect of the different parameters on turbine performance by analyzing the blade aerodynamics at various azimuthal locations. CFD analysis showed that the blade extracts most of the power in the frontal half of its circular trajectory and in some cases even lose power in the rear half. This study clearly indicates the potential for major improvements in VAWT performance with novel blade kinematics, optimal chord/radius ratio, and using cambered blades.
CarterCopter Technology Goes Offshore: Commercial Variant with Full Hover Capability
Authors:   Carter Aviation Technologies, Carter Jay , Lewis Jeffrey
Published: October 2024

Carter Aviation Technologies, LLC has been developing its Slowed Rotor/Compound (SR/C™) technology for over 20 years. A key enabler of the SR/C technology is a rotor and related control system that permits high advance ratio flight while maintaining rotor stability. Carter has demonstrated this capability in flight with its Personal Air Vehicle (PAV), which has jump takeoff and zero-roll landing capability. A decade ago, Carter established a full hovering configuration employing SR/C technology in response to the Joint Heavy Lift (JHL) requirement. Today, Carter is taking that same approach, but sized for the offshore oil platform service mission. This paper briefly describes the history of SR/C development and the JHL configuration, and then focuses on the Carter CC-221, a new platform aimed at the offshore oil rotorcraft market. The development and analysis of the CC-221 configuration demonstrates that Carter's SR/C technology is directly applicable to hovering aircraft with performance that is very attractive, particularly for those missions requiring high speed and/or long range.
New Trimming Strategy for Predicting of the Unsteady Aerodynamic Characteristics of Tilt-rotor/Wing in Conversion Mode
Authors:   National Key Laboratory of Science and Technology on Rotorcraft Aeromechanics - Nanjing University of Aeronautics and Astronautics Nanjing, Peng Li , Qi-Jun Zhao , Qiu-Xian Zhu
Published: October 2024

Based on the flight state planning, a new predetermined trimming methodology has been established to investigate the tilt-rotor/wing operational characteristics under conversion flight condition. Firstly, in order to enhance aerodynamic forces computing precision of tilt-rotor, and overcome the dependency on the test data, the two CFD models including Virtual Blade Model (VBM) and Real Blade Model (RBM) are established to simulate the unsteady flowfield of tilt-rotor in conversion mode. In the two CFD models, RANS equations are employed as government equations, and the implicit LU-SGS method is used for temporal discretization. Secondly, the two simplified aerodynamic models containing Conventional Rotor Model (CRM) and the new Momentum Actuator Disk Model (MADM) are proposed to improve the computing efficiency of trimming. Additionally, the trimming strategy has been developed based upon the CFD models and the simplified aerodynamic models for the conversion flight condition. After verifying the effectiveness of the above numerical method on calculating the aerodynamic forces of rotor and tilt-rotor, the conversion envelope of XV-15 tilt-rotor is determined by the CRM, and manipulations of XV-15 tilt-rotor in different conversion flight procedures are calculated. Finally, the RBM is employed to simulate the flowfield of XV-15 tilt-rotor in three typical states with trimming.
Evaluation relationship between VDR gene and clinical and inflammatory factors in patients with RRMS
Authors: Milanifard Maryam , Mehrabi Soraya , Ahadi Reza , Nabiuni Mohsen , Souteh Samaneh Azimi , Joghataei Mohammad Taghi
Published: October 2024

Introduction: Adipocyte levels including leptin and FABS-4 levels, adiponectin, obesity, and vitamin D can be related to the occurrence and exacerbation of MS disease.
Objective: This research aimed at determining the relationship between VDR gene changes and clinical and inflammatory factors in patients with relapsing-remitting multiple sclerosis (RRMS).
Method: This case/control study was conducted based on the ethical principles of Helsinki. RRMS disease was confirmed based on history, clinical signs, radiological signs, and neurologist's diagnosis. The research population consisted of healthy people and patients with RRMS referring to Hazrat Rasool Akram Hospital between 2021 and 2023 who met the criteria for entering the research.
Results: FokI polymorphism is associated with a substantial increase in risk, with an odds ratio of 7.28, for those with the FF genotype who have RRMS compared to healthy individuals (OR=7.28: 95% CI; 1.86, 28.41). The presence of FokI polymorphism significantly raises the likelihood of developing RRMS in persons with the FF genotype compared to healthy individuals, with an odds ratio of 28.7. RRMS patients with genotypes did not exhibit a significant increase in risk compared to controls for FokI, ApaI, TaqI, and BsmI polymorphisms.
Conclusion: None of the studied polymorphisms revealed a significant risk in obese patients with different genotypes compared to the obese people. Further research, including more cases, is needed to avoid results that could be inflated by small samples or low frequencies of minor alleles.
Vienna: one year later
Authors: Antico Leonardo
Published: October 2024

A commission delegated by the World Assembly on Ageing (Vienna, July 1982) carried out its work in parallel with the Plenary Assembly and drew up an International Plan of Action on Ageing, which was adopted after a short time by the General Assembly of the United Nations (UN).
Psyche and spirit: the encounter between psychological science and theology
Authors: Spinsanti Sandro
Published: October 2024

The long history of suspicion and opposition between depth psychology and religious institutions is well known. The coryphaei of psychoanalysis - Freud, Adler and Jung - believed that religion, especially in its institutional aspect, had a pathogenic effect on the psyche. The qualification of religion as an ‘obsessive neurosis’ was experienced by believers as a whipping in the face, which hindered the initiation of dialogue with those who so radically disqualified the experience of others.
From the Hippocratic Oath to modern deontological codes: continuity or overcoming?
Authors: Altamura Bruno M.
Published: October 2024

Even if the Hippocratic Oath in its enlightened synthesis encapsulates the essence of the great master's deontological teachings, there is no doubt that a more complete picture of Hippocratic ethics can be gleaned from the contents of the entire Corpus Hippocraticum, and it matters little if the various writings contained therein are not all attributable to him, but are in fact the work of various authors who lived between the 5th and 2nd centuries BC.
Logistics and port performance of South Africa: Do the numbers add up?
Authors: Joynt Hubert
Published: October 2024

N/A
Subcutaneous Panniculitis-like T-cell Lymphoma
Authors: Mandli Sonal , Oza Rutu Harsh , Sutaria Amita H , Shah Bela J
Published: October 2024

Subcutaneous panniculitis-like T-cell lymphoma (SPTCL) is a primary, rare cutaneous T-cell lymphoma that resembles panniculitis and accounts for <1% of all peripheral T-cell lymphomas. It is characterized by multiple subcutaneous nodules and plaques, which usually involve the extremities. Histopathological findings include the presence of neoplastic T-cell surround and disrupt individual adipocyte membranes. Immunohistochemistry will confirm diagnosis by CD8+ and CD56− cells. Here, we report a case of a 29-year-old female who presented with cutaneous panniculitis-like lesions diagnosed with cutaneous T-cell lymphoma with the help of histopathology and immunohistochemistry.
Radiographic differences in deep fascial space infections versus localized acute apical abscesses: A cone-beam computed tomographic-based observational study
Authors: Gallegos John , Tahmasbi Mehranz , Jalali Poorya
Published: October 2024

Aim:

The objective of this study was to evaluate anatomical differences and patterns of bone loss in patients with acute apical abscess (AAA) clinically presenting as a localized swelling or with concomitant fascial space involvement (FSI) using cone-beam computed tomographic (CBCT) imaging.

Methods:

Thirty CBCT images of AAA cases presenting with fascial space involvement (FSI) and 31 cases of localized acute apical abscess (LAAA) were evaluated. Factors that were recorded included the presence/absence of cortical disruption, the distance of the involved tooth apex to the buccal and lingual/palatal cortex, the length of the anatomic root/s of the involved tooth, and the volume of the endodontic lesions.

Results:

The median for the volume of the lesions was 138 mm3 for the FSI group and 154 mm3 for the LAAA group (P > 0.05). Radiographic evidence of cortical disruption was seen in 26.7% of the cases with FSI and 41.9% of the cases with LAAA (P > 0.05). The mean for the distance of the apex to the buccal cortex was the only statistically significant difference between the two groups and was 4.2 mm for the FSI group and 3 mm for the LAAA group (P < 0.05).

Conclusion:

CBCT assessment showed root apices associated with fascial space involvement tended to be more confined in cancellous bone. Although a significant difference between the two conditions was found, the inflammatory process is complex, and CBCT assessment alone cannot predict AAA remaining as a localized swelling versus spreading to fascial spaces.
Enhancing Document Clustering with Hybrid Recurrent Neural Networks and Autoencoders: A Robust Approach for Effective Semantic Organization of Large Textual Datasets
Authors: Dodda Ratnam , Alladi Suresh Babu
Published: October 2024

This research presents an innovative document clustering method that uses recurrent neural networks (RNNs) and autoencoders. RNNs capture sequential dependencies while autoencoders improve feature representation. The hybrid model, tested on different datasets (20-Newsgroup, Reuters, BBC Sports), outperforms traditional clustering, revealing semantic relationships and robustness to noise. Preprocessing includes denoising techniques (stemming, lemmatization, tokenization, stopword removal) to ensure a refined data set. Evaluation metrics (adjusted randomness evaluation, normalized mutual information evaluation, completeness evaluation, homogeneity evaluation, V-measure, accuracy) validate the effectiveness of the model and provide a powerful solution for organizing and understanding large text datasets.
Normative data for the lateralization task in the assessment of intranasal trigeminal function
Authors: Mai Y , Hernandez A K , Konstantinidis I , Haehner A , Hummel T
Published: October 2024

Aim: To provide normative data for the lateralization task in the assessment of intranasal trigeminal function, as well as to investigate potential effects of age, sex and olfactory function. Methods: The lateralization task using eucalyptus as target stimulus was performed to assess intranasal trigeminal function. Data were collected from: 360 healthy adult participants (mean age 37.5±17.4) for the 40-trial version; 284 participants (mean age 32.6±14.1) for the 20-trial version; and 418 participants (mean age 42.6±15.6) for the 10-trial version. The “Sniffin’ Sticks” test was used to measure olfactory function. Results: The mean scores were 35.46±4.50 for the 40-trial version, 15.64±3.65 for the 20-trial version, and 8.14±2.16 for the 10-trial version. In the reference group aged 18-25 years, the 10th percentiles were 33 for the 40-trial version, 11 for the 20-trial version, and 6 for the 10-trial version. Significant effects of age and odor discrimination score were observed on lateralization performance. Conclusions: We provide reference scores for the lateralization task, in large sample of healthy participants. Among the three examined tasks (40, 20 and 10), the 40-trial task yielded the most reliable information. For the 40-trial version, scores equal or higher to 33 points indicate a normal lateralization ability, whereas scores between 27 and 32 may warrant further assessment. Scores below 27 possibly point towards a decreased trigeminal function. The lateralization task serves as surrogate marker of intranasal trigeminal functions and further studies with pathological cases are needed to explore its clinical usefulness.