bluuebunny/crossref_metadata_2025 huggingface dataset:
Embracing Self-Compassion
Authors: Sowmya D. S.
Published: September 2024

This study explores the fundamental elements of self-compassion and the theoretical framework that supports its transforming nature, delving into the significant effects of self-compassion on student well-being. This research tackles the subtleties of adopting self-compassion practices across varied student demographics, including the impact of environmental and cultural factors. The presentation of evidence-based tactics and useful insights for developing self-compassion provides educators and administrators with a thorough manual for incorporating these ideas into the operations of their organizations. We examine alternatives for interventions as we navigate the difficulties in teaching kids self-compassion. Beyond present methods, future avenues for study and implementation in the field of student well-being are explored in this conversation. Understanding the shifting opportunities and challenges in education is crucial as it continues to change.
ChatGPT and AI in Government
Authors: Dwivedi Dwijendra Nath , Mahanty Ghanashyama , Dwivedi Varunendra nath
Published: September 2024

This chapter explores the transformative impact of artificial intelligence (AI) and ChatGPT techniques in facilitating real-time data-driven decision-making within government sectors. The adoption of AI and advanced language models like ChatGPT represents a significant shift in how governments process vast amounts of information to make timely and informed decisions. The research focuses on the application of these technologies in enhancing governmental operations, policy-making, and public services. Case studies are presented to illustrate the practical applications of these technologies in various government functions such as public health management, accelerating teaching and learning, urban planning, environmental monitoring, and emergency response. Additionally, the chapter addresses the ethical considerations and the need for robust data governance frameworks to ensure the responsible use of AI in government. This includes discussion on data privacy, security, and the potential risks of bias in AI models.
Opening Up the Next Generation of Convolutional Neural Networks (CNN) for Palm Recognition
Authors: Sisodia Dilip , Verma Charu Vaibhav , Joshi Garima , Kaliyamoorthi P. , Gupta Ankur , Pramanik Sabyasachi , Mohammad Faiz
Published: September 2024

A subset of biometrics called palm recognition has drawn a lot of interest because of its potential applications in a variety of fields, including as security systems and human-computer interaction. Convolutional neural networks (CNNs) are being used in this effort to look at the creation of a palm detecting system. In order to identify and classify palm orientation in digital photos, deep learning will be used. An essential part of the study is data collection, which comprises compiling a large dataset of accurately labeled palm photos for supervised learning. The authors handle data preparation and use methods like image scaling, pixel normalization, and data augmentation to get datasets ready for model training. The system is based on a CNN model architecture, which creates a neural network with the ability to intelligently classify and automatically gather data from palm photos. Convolutional layers are used in this architecture to extract features, while fully connected layers are used for classification.
Reshaping Human Resource Management
Authors: Yılmaz Sıdıka Ece
Published: September 2024

The COVID-19 pandemic has had a major effect on the field of Human Resource Management HRM, prompting quick adaptation and innovation by organizations around the world. This chapter examines the pandemic's multifaceted effects on HRM practices, highlighting both the challenges that were encountered and the innovative measures implemented in response. The pandemic has hastened the adoption of digital technology, resulting in a considerable increase in remote work habits and digital transformation within organizations. While these developments have increased operational efficiency, they have also raised worries about employees' digital abilities, privacy, and the blurring of work-life boundaries. The epidemic has highlighted the significance of strategic workforce planning, with HRM practitioners focusing on improving employee skills, well-being, and engagement. This chapter will provide an in-depth overview of these changes, exploring the evolution of HRM practices and identifying the most effective ways for navigating the challenges created by the pandemic.
Nurturing Excellence
Authors: Ganguly Deeksha Gupta , Sinha Deepti , Bhaumik Vandita , Varghese Ronit
Published: September 2024

Job satisfaction and Employee engagement are critical to the success of any business, particularly in the education sector. This study examines the relationship between job satisfaction and employee engagement in the education sector, focusing on Delhi NCR. The research uses collection of data from 16 educators through semi structured interviews. It is based on Interpretative Phenomenological Analysis (IPA) tool to examine the factors affecting employee engagement and job satisfaction. The findings aim to improve teaching quality, student outcomes, and institutional effectiveness. However, the study has limitations, including subjectivity, risk of bias, and being limited to the educational sector. Despite these limitations, the study contributes to the existing knowledge by revealing the dynamics of work satisfaction and employee engagement in the education sector, providing valuable insights for organizational management and policy formation.
Artificial Intelligence in Human Resource Management Training
Authors: Orhan Alev , Kurnaz Salim
Published: September 2024

The objective of this study is to conduct a bibliometric analysis of the keyword network, numerical distribution by years, citation network of the most frequently cited publications, most active researchers, most active journals, countries and institutions of the studies published in the field of human resource management education between 1990 and May 1, 2024 in the WOS database. Furthermore, the objectives of the studies examined in the research are analysed in order to identify the trends of research in the field of artificial intelligence in human resources management and the remaining gaps in the research area. In the study, the criterion sampling method, one of the purposive sampling methods, was selected. The research is a descriptive content analysis study employing qualitative research methods. The R Programming Language “biblioshiny” package program was employed in the analysis of the data collected for the initial objective of the study, while MAXQDA 2020 (20.4.0) was utilized in the second stage.
Plasmonic-Metal Nanostructures-Enhanced Photoconductive Terahertz Emission and Detection
Authors: Nomoev Sergey , Vasilevskii Ivan , Klochkov Alexey , Vinichenko Alexander , Khartaeva Erzhena
Published: September 2024

Photoconductive antennas based on low-temperature gallium arsenide (LT-GaAs) with a gold plasmonic-gold grating made of nanorods and nanoislands have been developed and fabricated. The antennas were produced using molecular beam epitaxy and electron-beam nanolithography. LT-GaAs samples with a high annealing temperature of 943 K were employed in the fabrication process. It has been demonstrated that plasmonic nanostructures significantly enhance the efficiency of light-to-terahertz radiation conversion by photoconductive antennas.
Manning Coefficient Effect on the Shallow Water Flow Equation
Authors: Kurz Gustavo Braz , de Quadros Régis Sperotto , Vaz Linn Renato
Published: September 2024

This work will seek to solve shallow water equations, using numerical integration methods, to solve partial differential equations (PDEs) and subsequently present a brief physical interpretation of the solutions. The derivation of the equations is demonstrated, along with the explanation of each physical quantity present. The discretization of non-conservative shallow water equations is carried out using the method of finite differences advanced in time and central in space (FTCS), in explicit form. With the deductions, different Manning coefficients will be addressed in the solutions, verifying their effects.
Rethinking antibiotic misuse in healthcare: the need to address the person and wider determinants
Authors: Liyanapathirana Veranja
Published: September 2024

No abstract available
Antibiotic prescription in critical care units in Sri Lanka: a prospective multi-centre survey
Authors: Priyankara Dilshan , Mudalige Anushka , Lokuge Manik , Samaranayake Waruni , Sanjeeva Eranda , Mohomed Makarim , Wanigasuriya Rasanee , Punchihewa Dinesha , Subasinghe Lilanthi , Mendis Anthony , Muthulingam Navaneedan , Manathunga Supun , Abeyagunawardena Ishanya
Published: September 2024

Introduction: Antibiotic stewardship is the effort to measure and improve how antibiotics are prescribed.We conducted a survey of antibiotics prescribed in critical care (CC) units in Sri Lanka to identify areas for improvement.Methods: Data was collected using a questionnaire from selected CC units in six tertiary care hospitals across Sri Lanka over six months. Data was collected on one particular day in every 2nd and 4th week of the month. Data was compiled using a google sheet and it was analyzed using R language.Results: Data from 237 adult patients was analyzed. Antibiotics were commenced according to microbiology advice (39%), local guidelines (14%), culture results (5.9%), a combination of above (27.1%) and in 14%, none of the above. A majority (39%) were prescribed two antimicrobials, whereas 35%, 18% and 5.9% were on one, three and four antibiotics respectively. The most common indication was hospital acquired pneumonia (HAP)(29.1%), followed by community acquired pneumonia (20%). In 25% of patients, no specific indication for antibiotics was noted. Only 47% of patients had all their antibiotics reviewed and updated, whereas antibiotics were not reviewed at all in 43%. The most frequently prescribed antibiotic was meropenem (32.9%) followed by piperacillin-tazobactam (22.3%) and ceftriaxone (20.6%).Conclusion: HAP was the main indication for antibiotics in critical care. Compliance on antibiotic prescription and documentation is inadequate and the extensive use of meropenem remains a cause for concern. Therefore, strict antibiotic stewardship guidelines and regular review of antibiotics are indicated in critical care units.
Analysis and Testing of Boundary-Layer-Ingesting Pusher Propeller for High Speed Rotorcraft
Authors:   UTRC, Moffitt Blake , Bowles Patrick , Joo Jongwook , Min Byung-Young , Wake Brian
Published: September 2024

Historically, pusher propeller configurations have been rare in all aircraft due to challenges in analysis and modeling, reduced installed efficiency, difficulties with cooling, and takeoff rotation limitations. As a result of being rare, little analysis or experimental data exists on pusher propellers, and data that exists is outdated and only marginally relevant to modern rotorcraft designs. With the development of high-speed rotorcraft configurations such as the Sikorsky X2 Technology™ Demonstrator (X2TD), a better understanding is needed of the design and expected performance of a pusher propeller operating directly in the aircraft fuselage wake. This paper describes a fundamental pusher propulsion study consisting of both analysis and wind tunnel experiments that provides data to help better understand, analyze, and design pusher propeller aircraft. The study focused on capturing the interaction between an axisymmetric rotorcraft-like fuselage body with a rear-mounted pusher propeller. Analysis was conducted using Computational Fluid Dynamics (CFD). Experiments designed to capture the interaction between the fuselage and the pusher propeller were conducted using a 16 in. diameter propeller in the UTRC low speed wind tunnel. Experiments and analysis of a propeller in isolation (no fuselage), the fuselage in isolation (sans propeller), and the combined fuselage and operating propeller are presented. CFD and experimental data were in good agreement and showed similar performance trends. Data showed that for most operating conditions, the pusher propeller installed performance was significantly higher (up to 5 net efficiency points) vs. the same propeller operating in isolation. In addition, an increase in drag proportional to propeller thrust was also observed. Overall, the results demonstrated the possibility of obtaining a net propulsive efficiency benefit by using a pusher-propeller configuration which can result in improved performance of high speed rotorcraft as well as fixed-wing aircraft with similar fuselage/propeller configurations.
Large Eddy Simulation of Flow over an Airfoil Undergoing Surging and Pitching Motions
Authors:   Rensselaer Polytechnic Institute, Kocher Alexander , Cummings Reed , Sahni Onkar
Published: September 2024

A dynamic large eddy simulation (LES) approach is employed to study flow over an oscillating NACA 0018 airfoil with surging and pitching motions. Surging motion is studied at moderate and large advance ratios of λ=0.5 and 1.0, and a reduced frequency of k=0.0985. An airfoil at fixed incidence of 8° is set in a constant freestream flow at Reynolds number of ReC=300,000. LES predictions for lift force are compared to experimental results at λ=0.5 and show a good agreement. LES predictions are also made at λ=1.0 which is at the tipping point of reverse flow regime. With a large surging amplitude, there is a loss of lift during the retreating phase, and a roll up and ejection of a distinct leading-edge vortex. Pitching motion is studied at ReC=250,000 and k=0.074 with both mean and amplitude of incidence set to 10°. Again, LES predictions for lift force are compared with experiments. Unsteady Reynolds-averaged Navier-Stokes (URANS) predictions are also made. LES predictions show similar features in the force response as experiments while URANS lack few prominent features. In all cases, instantaneous flowfield is analyzed at different phases.
High-Performance-Rotor Aerodynamic Testing
Authors:   Sikorsky Aircraft, Scott Mark ,   US Army - Aviation Development Directorate, Thomas Mathew
Published: September 2024

A whirl and wind tunnel test was conducted to measure performance and stall vibration benefits associated with a novel Retreating Side Blowing (RSB) concept, Miniature Trailing edge Effectors (MiTEs), and Lateral Lift Offset (LLO) trim. A new 28 ft diameter rotor mounted to an articulated S-76R rotor hub was flown at the National Full Scale Aerodynamics Complex (NFAC). Technical objectives were slightly improved performance and significantly reduced retreating blade stall vibration at high blade loading-advance ratio combinations. The blades were well instrumented with five fully strain gauged spanwise locations as well as external, internal, and blowing slot pressure and temperature sensors. Retreating blade stall conditions were reached between 0.24 to 0.61 advance ratios. The RSB pumping power and slot profile drag effects reduced L/De at mid blade loadings but leading edge blowing regained the performance loss at high blade loadings. The MiTEs showed a slight L/De improvement at high blade loadings. Lateral lift offset showed up to 35% L/De improvements as blade loading was increased. The RSB concept slightly reduced retreating side torsional vibration. The RSB dynamic lift and moment improvements were not as beneficial as expected due to the dynamic Mach number on the retreating side. The MiTEs reduced retreating blade stall vibration by 20% to 40%. Test data revealed rotor blade peak torsional vibration was not improved above advance ratio 0.32 by any concept. This is because peak torsional blade loads were not generated by retreating side stall. They were generated roughly between 20 deg and 200 deg azimuth positions. Therefore even if the retreating side technologies worked perfectly the rotor stall boundary would not have improved. Subsequent review of UH-60A slowed rotor and AH-56A flight test data show the same phenomena.
Method for Estimating Inertial Properties of Rotorcraft in Conceptual Design
Authors:   NASA Ames Research Center, Gallaher Andrew
Published: September 2024

The conceptual design of aircraft is a continuously evolving and expanding discipline where the primary task is to perform a trade-space analysis to meet a set of operational and performance requirements. One of the major aspects of conceptual design is mass properties analysis, which involves analyzing the mass distribution of an aircraft layout. The results of this analysis can be used in other aspects of the design process: handling qualities analysis, packaging layout, control surface sizing, and inertial loading for structural design. Traditionally, and when not performed using parametric databases, mass properties is a time consuming process. The analysis requires an initial layout of both the aircraft outer mold-line (OML) shaping and internal component placement. At which point, handbook methods or Computer Aided Design (CAD) software are leveraged to analyze the distribution of mass in the aircraft layout. Presented herein is a method for automating the mass properties analysis of a conceptual aircraft design by leveraging light-weight scriptable CAD software capability, outputs from aircraft conceptual performance and sizing software, methods for geometrically representing rotor systems, and parametric scaling rules for internal component placement. This method quickly and accurately returns inertial estimates for a variety of rotorcraft configurations allowing for trade-space exploration.
Development and Flight Testing of the Gamera-S Solar Powered Helicopter
Authors:   University of Maryland, Jordan Scott , DeGraw Tyler , Mahon Michelle , Murphy George , Chopra Inderjit , Nagaraj V.
Published: September 2024

Gamera-S, a solar powered helicopter designed and constructed by undergraduate students at the University of Maryland flew several times in 2016 with a maximum recorded flight time of 9 seconds with a pilot on board. Using highly efficient rotors and airframe, the vehicle was able to achieve liftoff with 1.6 horsepower supplied directly from on-board solar panels. Gamera-S is a significant step towards green aeronautics.
Model Based Engineering for Advanced Integrated Modular Avionics - Focus and Challenges
Authors:   Lockheed Martin, Gaska Thomas ,   Binghamton University, Summerville Doug , Gaska Marilyn , Chen Yu
Published: September 2024

Advanced Integrated Modular Avionics (A-IMA) will drive new focus and challenges for Model Based Engineering (MBE). First, there is the need to bridge MBE to legacy system elements that were developed without MBE along with the need to handle hybrid Open System Architecture / Integrated Modular Avionics (OSA/IMA) based architectures. Second, there is the need for MBE to be reusable and interoperable across product development cycles as technology insertions occur. Third, there is the need for integration of MBE into synthesizable descriptions that can also be effectively validated for mixed general purpose, safety, and secure computing and networking environments. Fourth is the need for effective application of MBE in hybrid waterfall and agile development environments where target infrastructure is scalable in capability and cost. Fifth is the need for MBE to support partitioned roles across companies, government, and universities where one entity does requirements, one does architecture, one develops components, one provides formal test, and another provides system sustainment. There are a number of industry and university efforts underway to address these focus items and challenges spread across these adjacent MBE complex system domains.
This paper is focused on the current state of each of these areas relative to use in A-IMA systems based on industry initiatives and academic research. It uses the driverless car for comparison as an emerging "Advanced Integrated Modular Architecture" and identifies its parallel approaches to address these focused items and challenges. This work is being built on the authors' work exploring dual use technologies being developed for the driverless car domain that will lead to a market of 10 Million autonomous cars operating in 2020. Previous papers have addressed identification of potential advanced automotive dual use transformational hardware and software technologies including many core processing, advanced software autonomy and data fusion components, unified mixed criticality networking, and integrated cyber security for A-IMA. A testbed has also been recently proposed as a mechanism to evaluate these dual use technologies in an A-IMA context. This paper extends the dual use view to include understanding of the best-of-breed avionics MBE environment and how it can be complementary to leveraging a testbed environment in addressing affordable, scalable, and open solutions.
Evaluation of Aircrew Whole-Body Vibration and Mitigation Solutions for Helicopter Flight Engineers
Authors:   National Research Council Canada, Chen Yong , Yapa Upekha , Price Andrew , Wickramasinghe Viresh
Published: September 2024

Flight testing has been performed on a Bell-205 helicopter to investigate aircrew whole-body vibration (WBV) exposure levels on a rag and tube Flight Engineer (FE) seat in accordance with ISO2631 and MIL-STD1472 standards. Results show that the helicopter cabin vibration is dominated by the N/rev harmonics of the two-bladed main rotor speed. The aircrew WBV levels vary significantly depending on the flight conditions; the highest WBV levels occur at high speed level flight conditions. With reference to the ISO2631 and MIL-STD-1472 guidelines, the aircrew WBV exposure level on the standard FE seat in the entire tested flight profile is qualitatively rated as "uncomfortable". Limiting the maximum duration of such missions to 1 hour would ensure compliance with the limit of ISO2631 vibration health and risk guideline "Caution Zone". It is also noted that the use of gunner seat insert cushion for combat missions can lead to a significant increase in the aircrew WBV levels. However, the use of selected carry-on cushion pads can provide an effective WBV mitigation to the aircrew in the majority of flight conditions. Further occupant WBV tests on a human rated mechanical shaker table also verified that selected carryon seat cushion pads are also effective in the mitigation of occupant WBV levels on the Bell-412 helicopter.
Degraded Visual Environment Mitigation (DVE-M) Program, Yuma 2016 Flight Trials in Brownout
Authors:   US Army ADD, Szoboszlay Zoltan ,   US Army Research Lab, Davis Bradley , Fujizawa Brian , Minor Joe , Osmon Michael , Morford Zachariah
Published: September 2024

A flight test was conducted by the U.S. Army Degraded Visual Environment Mitigation (DVE-M) program in an EH-60L helicopter at Yuma Proving Ground. The pilots used an integrated combination of multispectral terrain/obstacle sensors, pilot cueing, and improved flight control to accomplish 64 landings and 55 precision hover maneuvers in heavy brownout conditions. Approach guidance was provided as a target horizontal speed and target vertical speed on the pilot's displays. Sensor-driven guidance was developed but not used due to the large number of false-positive returns. All 64 landings were safe. Landings were all within 22 ft (mean 5.8 ft) of the target landing point as measured with the EGI inertial sensor. Lateral speed at touchdown was always within 1.5 knots (mean 0.3 knots). Vertical speed at touchdown was always within 180 ft/min (mean 97 ft/min). Six go-around maneuvers due to pilot performance were conducted safely by the pilots using the cueing. Pilots reported that they had little spare capacity to interpret the sensor image since they were focused on following the approach guidance cues on the display. Hover and landing maneuvers were compared with and without coupled collective. Pilots reported a major reduction in workload with coupled collective as measured on the Bedford scale for both landing and hover. With coupled collective hover position keeping improved. Heading hold was available and used on all maneuvers. Aural cueing was rated highly as implemented in this test. Tactile (vibrating seat, waist belt, and shoulder strap) was rated poor as implemented on this test on the subjective usability questionnaire. In particular, pilots requested that only one axis be active at a time, and that tolerances be loosened.
Degraded Visual Environment Operational Levels
Authors:   Boeing, Fenley Stephen ,   US Army, Graham Daniel , Gideonse Rick
Published: September 2024

The original abstract was titled "Degraded Visual Environment Categories" and in the process of performing the work, it was determined that "Operational Level" was a more relevant term than "category", hence the title change. Degraded Visual Environment (DVE) is a complex topic and not all aircraft or rotorcraft have the same mission or same DVE requirements. While this paper is not assuming a clean sheet of paper approach to defining the problem, it attempts to provide a different view of the problem in the context of Army Attack and Reconnaissance aircraft. The intent is to create a frame work in which the problem can be broken up into smaller pieces using operational contexts that are defined within this paper as operational levels based on visibility and terrain flight levels for Attack aircraft operations under DVE conditions. The objective is to define the problem so that a worst-case problem does not have to be solved first. This is important, because for the near-term, identifying a practical worst-case solution would be unlikely, and without the complete operational context, it would not be as obvious what solutions could provide interim value.
Proprotor Loads and Whirl-Flutter Stability of a Tiltrotor Wind Tunnel Model
Authors:   University of Alabama, Hoover Christian ,   US Army Research Laboratory, Kang Hao , Shen Jinwei , Kreshock Andrew
Published: September 2024

This paper studies the blade loads and whirl-flutter stability of a three bladed stiff-inplane tiltrotor wind tunnel model mounted on the Wing and Rotor Aeroelastic Test System (WRATS). Proprotor loads are predicted and compared with the WRATS model at different pylon conversion angles. The tiltrotor whirl flutter stability is predicted and tested in airplane mode. The analytical models are developed with three rotorcraft codes: RCAS, CAMRAD II, and Dymore. The Dymore and RCAS models contain the structural model of the wing/pylon fixed system whereas the CAMRAD II model for this study uses an isolated proprotor. The study indicates that the analytical models capture the overall vibratory flap and chord bending moments, however, miss the higher harmonics of the blade loads. The steady flap and chord bending moments predicted by CAMRAD II and Dymore differ in the torque tube and flexbeam region but agree along the span of the blade. RCAS shows a good prediction of the damping ratio of the chord and torsion modes of the WRATS stiff-inplane tiltrotor. Dymore captures the relative trends of these modal dampings but over-predicts the wing chord mode damping and under-predicts the wing torsion mode damping. Both analyses slightly over-predict the wing chord frequency.
RPM Driven Extension-Torsion Coupled Self-Twisting Rotor Blades
Authors:   University of Maryland, Ward Elizabeth , Chopra Inderjit , Datta Anubhav
Published: September 2024

This paper describes the effects of a composite coupled blade spar on the performance of a slowed RPM helicopter rotor in high speed edgewise flight. This study expands upon previous work that showed that antisymmetric composite coupling in the spar of a UH-60A-like rotor can provide a significant increase in the lift to drag ratio of a rotor when the RPM is reduced. The current analysis was performed using a full 3-D FEA based aeroelastic computational structural dynamics (CSD) solver, X3D, now with the inclusion of a freewake aerodynamics model. This was validated using existing UH-60A test data for high advance ratios. The current analysis shows that a blade with a nominal composite coupling can provide a maximum increase in the lift to drag ratio of approximately 1.3 at 85% of the nominal RPM (NR) of 27 rad/s and that hygrothermally stable layups do not degrade the rotor performance. However, close study of the strain in the rotor showed that a rotor with an extension-torsion coupled composite spar would unlikely be feasible at 27 rad/s as the axial strains felt by the rotor around the azimuth often exceed the allowable tensile strain of 6000 με. The details of what can be done to reduce the axial strain at all rotational speeds is part of an ongoing investigation.
Effect of Elastic Blade Deformation on Trim and Vibratory Loads of a Quadcopter
Authors:   Rensselaer Polytechnic Institute, Niemiec Robert , Gandhi Farhan
Published: September 2024

This study examines the effect of rotor blade elastic deformations on a quadcopter in forward flight conditions. The blade equations are discretized using the Galerkin method and the blade periodic response is calculated using the harmonic balance method. Simulations are conducted on a 2 kg quadcopter with 12 inch diameter two-bladed rotors. The blade root vertical shear, flap bending moment and drag shear showed a strong 1/rev variation due to the azimuthal variation in aerodynamic loads. Elastic blade deformations did not affect the aerodynamic loads but the addition of in-phase 1/rev inertial loads resulted in net increases of 28%, 36% and 48% in the 1/rev blade root vertical shear, flap bending moment, and drag shear, respectively, at a forward flight speed of 10 m/s. The in-plane elastic deformations further introduced a 1/rev blade root radial shear due to the radial Coriolis force. At 10 m/s forward flight speed, accounting for elastic blade deformations resulted in a 7.6% reduction in the steady hub drag force, a 37% increase in steady hub roll moment, and a 15% increase in steady hub pitching moment that requires a 12% higher pitch RPM control input to trim the quadcopter. Increases of 103% in the 2/rev rotor hub in-plane loads (drag and side force), of 12% in the 2/rev hub vertical force, and of 25% in the 2/rev hub pitching and rolling moments were also observed. Since the forward rotor, lateral rotors, and the rear rotor operate at distinct rotational speeds, the aircraft is subject to vibratory loading at three different frequencies resulting in a beating phenomenon. The maximum amplitude of these oscillations equals the sum of the amplitudes of the three constituent vibrations, but reaches its maximum only once every twelve cycles. The 2/rev rotor hub vibratory moments are the dominant contributors to the aircraft pitch and roll vibrations, while the 2/rev rotor hub in-plane forces are the dominant contributors to the aircraft vibratory yaw moments. The blade phasing between the two lateral rotors has an effect on the magnitude of the total roll vibrations on the aircraft.
Reconstructing Spectra from IVHMS Condition Indicators
Authors:   Army Aviation Engineering Directorate, Wilson Andrew , Wade Daniel
Published: September 2024

The US Army collects high resolution vibration data from accelerometers on over 3000 rotorcraft. This data is used to diagnose the health of the drive system for the purposes of Condition Based Maintenance. This high resolution data is not always captured and saved, however features computed from it are always available. This paper uses a machine learning technique to estimate the high resolution data from the features with negligible error up to 20 kHz. The results indicate that the Condition Indicators represent the spectrums very well, which was not previously demonstrated or assumed.
Development and Application of a Hybrid System for Continuous Monitoring of Aircraft Gross Weight
Authors:   Sikorsky, Argenna Garrett , Davis Mark , Brookhart Andrew , Beale Ray
Published: September 2024

The ability to monitor gross weight (GW) of operational rotorcraft would result in increased safety and reduced maintenance costs. Due to these potential benefits, the aerospace community has investigated a number of approaches for monitoring GW. Heretofore, each approach has had inherent strengths and weaknesses that make them incomplete solutions by themselves for rotorcraft. For this reason, Sikorsky Aircraft Corporation has developed and demonstrated a novel system referenced herein as Hybrid GW Monitoring, which leverages the strengths of several approaches while significantly mitigating their weaknesses. This paper summarizes the development of the Hybrid GW Monitor, validation of its performance on flight test data, and lessons learned from its application to 500,000 flight hours of fleet data.
Integrated Hybrid Structural Management System (IHSMS) - Aircraft Impact Monitoring
Authors:   Sikorsky a Lockheed Martin Company, Schenck Eric ,   Vanderbilt University, Bond Raymond ,   NAVAIR Structures, Rusk David , Davis Mark , Meyer Janette
Published: September 2024

The Future Naval Capabilities Integrated Hybrid Structural Management System (IHSMS) program is developing Structural Health Management (SHM) capabilities for rotorcraft to move from conventional flight-hour based maintenance to reliability-based maintenance. A key element of IHSMS is to develop automated methods for impact detection, localization, and characterization. By their nature, impacts to rotor and airframe are random events that can trigger extensive inspections based solely on vague descriptions of the event by the aircraft crew. Operators must rely on numerous inspections to determine condition and ensure airworthiness, resulting in significant maintenance burden, both scheduled and unscheduled. The IHSMS program matured research originating at the Purdue Center for Systems Integrity (PCSI) at Purdue University and continued by the Laboratory for Systems Integrity and Reliability (LASIR) at Vanderbilt University, which uses a combination of physical sensors (accelerometers) and an algorithm to identify the location and estimate the force of impacts for both main rotor blade and airframe applications. This paper focuses on the outcomes of full-scale CH-53K main rotor blade and CH-53E airframe demonstration tests.
Component Life Management Using HUMS Data and Probabilistic Structural Integrity
Authors:   Sikorsky Aircraft, Bates Preston ,   United Technologies, Gurvich Mark ,   US Army ADD-AATD, Bordick Nathaniel , Sarlashkar Avinash , Davis Mark , Kiser Jay
Published: September 2024

A Health and Usage Monitoring System (HUMS) records a large number of flight parameters that can be utilized for regime recognition and tracking of individual rotorcraft usage. The availability of this information from a fleet offers the additional opportunity to work with these large datasets within an Advanced Structural Integrity Framework (ASIF) developed to perform reliability-based design and maintenance, considering durability and damage tolerance. Probabilistic analytical techniques were explored using a sample of UH-60 Integrated Vehicle Health Monitoring System (IVHMS) fleet data that was analyzed for the horizontal stabilator in a case study to estimate the reliability associated with a specified component replacement time and inspection interval. Probabilistic sensitivity studies showed that the deterministic design and substantiation practices used for the horizontal stabilator very closely approximated the industry accepted reliability levels for fatigue and crack growth. The probabilistic methodology also effectively utilized the available IVHMS regime recognition output, but the reliability results depended greatly on assumptions used to describe statistical distributions of key random input parameters, especially loads, which were not available from the fleet data for this component. The ASIF was shown to be a powerful tool for reliability-based management of rotorcraft structural integrity. Further work is needed to confidently configure and fully exploit such methods.
Affordable Design and Manufacturing of the V-280 Wing
Authors:   Bell Helicopter Textron Inc., Decker Ryan , Baines Andrew , Carlson Dave , Kooiman James , Stanney Keith , Wolfe Doug
Published: September 2024

The development of Bell's third-generation tiltrotor, the V-280, places great focus on achieving low cost and robust design simplicity and is demonstrated on the Joint Multi-Role (JMR) Air Vehicle Concept Demonstrator (AVCD). The design and manufacture of the V-280 AVCD wing structure is an example that achieves significant recurring and development cost savings through the infusion of Design for Manufacturing (DFM) principles, advanced materials, robust manufacturing processes, and low-cost developmental tooling. To drive simplicity through all aspects of the design, the V-280 AVCD wing employs a straight, constant section profile with no forward sweep or upward dihedral. Wing skins, spars, and ribs utilize a broad goods layup technique that favors large fabric ply shapes over highly tailored tape plies. This approach has yielded significant reduction in fabrication labor hours (via increased composite material application rates) and has resulted in reduced scrap material. Mechanical assembly hours are also reduced through use of room-temperature paste bonded structure as well as large scale use of determinant assembly methods. Multiple risk reduction test articles, produced concurrently with the design effort, helped to inform and validate the producibility and structural integrity of the final design configuration. New production methods applied to the V-280 demonstrator wing have yielded a projected 57% reduction in total labor hours and a 50% reduction in development tool costs. At the same time, a minimal capital investment profile is supporting the potential production rates necessary for a Future Vertical Lift (FVL) program of record.
State-Space Inflow Model Identification from Viscous Vortex Particle Method for Advanced Rotorcraft Configurations
Authors:   Advanced Rotorcraft Technologies Inc., He Chengjian ,   US Army ADD, Tischler Mark , Syal Monica , Juhasz Ondrej
Published: September 2024

This paper describes the methodology that identifies a state-space rotor induced inflow model from first-principle based viscous Vortex Particle Method (VPM) simulation for flight dynamics and control applications. Modern advanced rotorcraft configurations usually involve multiple rotors (e.g., co-axial), fans, wings, etc. where the aerodynamic interaction can be significant under certain flight conditions. The paper presents a unified state-space inflow formulation that addresses the aerodynamic interaction that is well suited for flight dynamics analysis and control design applications. In implementation, the unified inflow model is derived through system identification using VPM simulation generated data. The usage of first-principle based VPM provides a solid approach in capturing important rotor wake physics. This includes both the wake distortion and wake diffusion that are essential for an accurate interactional wake solution, without relying on empirical modeling parameters (e.g., vortex core size and wake dissipation parameters, etc.). The methodology of inflow model identification was first validated with a single rotor where measured data are available. Good agreement of the identified model response with the measurements was obtained. The methodology was further evaluated with a co-axial rotor system. Excellent correlation of the identified model with original VPM simulation was also obtained in both hover and forward flight.
HCE Kerosene Piston Engine Light Helicopter Demonstrator Results
Authors:   Airbus Helicopters, Mercier Christian , Gierczynski Alexandre
Published: September 2024

In the frame of GRC4, part of Cleansky's Green Rotorcraft Integrated Technology Demonstrator (ITD), Airbus Helicopters has led the development of a flying demonstrator based on the H120 serial helicopter and fitted with a designed from scratch reciprocating engine running on kerosene and named HCE for High-Compression Engine. On this research project Airbus Helicopters teamed with TEOS Powertrain Engineering, France, and AustroEngine GmbH, Austria, regrouped in the Consortium HIPE 440. Engine bench tests started in March 2013. Ground tests were completed in March 2015. With a Maiden Flight on November 6th 2015, the flight test campaign is to last until the end of 2017. This paper explains the specifics of the High Compression Engine, which triggered the need to build the new engine from scratch. It more particularly presents the achievements of the research project in terms of engine mass-to-power ratio, power output, fuel consumption, torque oscillations, engine displacements, rotor speed control and cooling system, which achievements where revealed during flight tests carried with up to 32°C OAT (ISA+17°C).
The Road to First Flight: Development of the CH-53K Drive System
Authors:   Sikorsky Aircraft, Palcic Peter ,   NAVAIRSYSCOM HQ, Leigh Leslie , He Shulin , Gmirya Yuriy
Published: September 2024

As the CH-53K program moved into manufacturing and test verification phase, a series of development challenges, such as overheating gearboxes, biased contact patterns of gear meshes and dynamic resonances of gearbox components were encountered during testing and were resolved through theoretical modeling and design modifications. This paper will present an overview discussion on how advanced analytical tools, such as computational fluid dynamics (CFD), Gleason T900 FEA (Finite Element Analysis) software, ANSOL Calyx customizable multiple dynamic and static, 2D and 3D FE based contact solver software, and FEA for dynamic modeling of structures, were used to simulate gearbox lubrication systems, optimize gear-train contact patterns, tune modal frequencies and damp resonances of gearbox internal components.
Engine Inlet Performance Analysis for the V-280 Demonstrator
Authors:   Bell Helicopter, Henson Brad
Published: September 2024

Engine inlet performance for the V-280 Air Vehicle Concept Demonstrator (AVCD) was evaluated for several different flight conditions including cruise, hover, and conversion mode. The analysis shows that the design provides sufficient pressure recovery while keeping the inlet's total pressure distortion within acceptable limits defined by the engine manufacturer, General Electric (GE). This paper discusses the tools and analytical methodologies used to perform the analysis. The approach allowed the V-280 AVCD design team to move forward with confidence that the engine would achieve performance margins to meet the program's flight test objectives.
Lightweight, Low-Cost, Damage-Tolerant, Highly Survivable Composite Drive Shaft for Helicopter Application
Authors:   SURVICE Engineering, Luzetsky Harry ,   Automated Dynamics, Michasiow John , Phifer Ellen
Published: September 2024

The ability to construct a composite, damage-resistant, highly survivable drive shaft for a rotary-wing application using an IM7 graphite/polyetheretherketone (PEEK) composite and in-situ tape-placement fabrication technology has been demonstrated. Through an evolutionary process, highly survivable, damage-tolerant shafts were developed, design tools and data were validated, and test shafts developed to evaluate the design viability in a dynamic application. The drive shafts demonstrated the feasibility of the technology, illustrated the ability to customize the design to meet unique shaft properties (e.g., frequency), and validated the maturity of the technology for rotary-wing applications.
Reliability Analysis of a Rotorcraft Transmission Bolted Connection
Authors:   Columbia Helicopters Inc., R. James , Rodriquez Steven , Pilkington Lawrence
Published: September 2024

Reliability analysis of a rotorcraft transmission bolted connection using actual service records data is the focus of this paper. The analysis is conducted for two different bolt materials used in the gearbox to evaluate the difference in reliability. As part of a continued operational safety bolt preload assurance check, the bolted connection between the spiral bevel ring gear and first stage sun gear undergoes a periodic field inspection: the inspection is said to have failed if the application of a prescribed torque to the nut causes the entire bolt assembly to spin. Reliability analysis employs a two-parameter Weibull probability density function to model the life of the bolted connection, with parameters derived using the Maximum Likelihood Estimator method. Results for each bolt type are discussed and an observation is made as one possible explanation for disparity in reliability levels for the two different bolt materials which is supported by direct measurement of bolt tension at initial assembly. As a result of the findings in this paper, recommendations for future work, including modification of the bolted connection assembly procedure, is discussed.
Expedient Repair for Composite Rotorcraft Structure
Authors:   US Army ADD, Robeson Mark ,   US Army - Prototype Integration Facility, Mellema Greg , Camp Daniel , Webb Joseph
Published: September 2024

The US Army has defined, analyzed, and executed a repair demonstration on a curved, stiffened, damaged composite panel. It was shown through analysis that most of the compressive buckling resistance of the panel is provided by its thickness and curvature, and that the composite repair patch largely restores the strength lost to the damage. Unique to this repair approach is the use of repair plies with interstices between yarns of the plain-weave carbon fabric repair patch plies, intended to increase surface area for enhanced bond strength. The repair demonstration showed good results in terms of visual inspection and porosity, and could typically be completed in 6-8 hours on thin-skin aviation composite structures. Verification of the repair is expected from upcoming structural testing.
Multifunctional Structural Composite with Integrated Electromagnetic Shielding
Authors:   SURVICE Engineering, Luzetsky Harry ,   Automated Dynamics, Ostrander Graham , Klein Martha
Published: September 2024

The ability to construct a multifunctional material that provides electromagnetic (EM) hardening on an aircraft structure integral to the material form has been demonstrated. The material's key attribute is the integration of a high level of EM shielding directly into a structural fiber-reinforced graphite composite in a manner that has minimal to no impact on the mechanical characteristics of the host composite. The material form has demonstrated the EM shielding equivalency of an aluminum electronics enclosure structure on a composite alternative for 25% of the weight without impacting structural characteristics. This material form provides a lightweight alternative to traditional means of providing aircraft EM protection from existing and emerging threats, such as high-power microwaves (HPMs) and EM pulse (EMP)/high-altitude EMP (HEMP), without incurring parasitic weight penalties. Its multifunctionality provides a weight-efficient means to address EM shielding in a composite while taking advantage of its strength-to-weight properties.
Development, Test, and Evaluation of Additively Manufactured Flight Critical Aircraft Components
Authors:   Naval Air Systems Command, Kasprzak Jan , Lass Amber , Miller Charles
Published: September 2024

The Naval Air Systems Command (NAVAIR) initiated an additive manufacturing (AM) demonstration effort with the following objectives: to gain experience with AM and the associated post-processing; to establish an AM process to produce and test flight-critical aircraft components; and to begin assessing paths towards standards and certification. A V-22 nacelle link and fitting assembly was selected for the demonstration effort. The performance of the AM produced components was compared to the original components and their design requirements. With the limits of this effort, it was determined that with proper processing, it is possible for AM materials to have strength properties that are comparable to those of wrought materials. The link and fitting assemblies showed sufficient structural properties through test and were installed on a V-22 test aircraft for a limited duration flight test. The components were recently granted a flight clearance for extended operations subject to a recurring daily inspection.