bluuebunny/crossref_metadata_2025 huggingface dataset:
The Benefits and Challenges of Using ChatGPT to Develop Programming Codes
Authors: Al-Shaar Walid
Published: September 2024

This chapter explores the use of ChatGPT, an AI-driven language model, in programming code development. It introduces ChatGPT, detailing its conceptual definition, historical evolution, features, and applications. The pivotal role of ChatGPT in code development, encompassing generation, debugging, and learning, is discussed. Advantages include heightened productivity, improved code quality, enhanced learning, secure code generation, reduced error risks, and increased creativity. Challenges involve limited comprehension, potential for erroneous or insecure code, overreliance, lack of transparency, job market impact, ethical concerns, and the future of programming. Practical applications include web development, debugging, and language learning. Best practices emphasize task definition, contextual information, code verification, and recognizing ChatGPT as a tool, not a substitute for human programmers. The chapter provides a concise overview, addressing benefits, challenges, practical examples, and best practices in utilizing ChatGPT for programming code development.
Digital Transformation in HRM
Authors: Türkyilmaz Serap
Published: September 2024

Nowadays, digital transformation is evident in all aspects of life as processes are being replaced with smart systems, enhancing satisfaction levels with increased online services.By converting traditional programs into modern digital programs, it facilitates the work of human resource managers. Along the way, in addition to having a specific goal, all ideas must be prioritized. To prevent any disruptions to work, everyone should have a comprehensive partnership in this system, along with the organization's culture. This section discusses the benefits, disadvantages, and key factors that lead to digital transformation in the organization, reducing time, error percentage, and costs separately.In addition to reducing risk, this strategic model also leads to learning new capabilities for sustainable feedback.
Legal Challenges in Managing Human Resources in the Public Sector
Authors: Matjošaityte Laura
Published: September 2024

This chapter examines the legal challenges facing the public sector in managing human resources, which can hinder excellent and efficient public administration. The chapter examines the legal challenges most encountered in the public sector due to its specific working conditions and legislative and regulatory requirements, such as ensuring equal opportunities, conflicts of interest, ensuring privacy and confidentiality of public servants, and other legally relevant aspects of human resource management in the civil service.
Heading Towards Robust Solutions
Authors: Jia Guimei
Published: September 2024

With the rapid development of information technology in the field of medicine, the acquisition and sharing of medical data show a significant growth trend. However, medical data involves sensitive information such as patients' clinical records, diagnostic results, and medical images, making data security and reasonable sharing a pressing challenge. Despite some progress in research on medical data sharing, the complexity and diversity of the issues persist. Various stakeholders in medical data, including medical institutions, researchers, and patients, have different expectations for data privacy protection, adding to the complexity of the challenge. Against this background, this paper focuses on the application of anomaly detection technology and proposes the GAN-Transformer model. This model cleverly combines Generative Adversarial Networks (GAN) with Transformer networks, creating a powerful and balanced framework for anomaly detection.
Specifics of Experimental and Fem Approaches in Structural Integrity Assesment of Penstock Made of HSLA Steel
Authors: Jeremić Lazar , Sedmak Simon , Đorđević Branislav , Aranđelović Mihajlo , Jovanović Aleksandar , Petrovski Blagoj
Published: September 2024

Taking into account the history of problems concerning high-strength low-alloyed (HSLA) steel used for manufacturing of penstocks (partly presented by authors in previous studies), this paper is oriented toward specifics on structural integrity assessment of construction in question. Experimental testing of parent material, i.e. HSLA steel, such as microstructure analysis, impact toughness testing and hardness measuring provide insight into characteristics of parent material properties. Considering geometry of penstock and specific requirements, finite element method (FEM), i.e. ABAQUS, was used to assess the structural integrity of penstock as a whole, specific the longitudinal welded joint under the different internal (working) pressure. It should be emphasized that a slight undermatching effect was investigated by FEM approach in this case. Focus is being put on plastic deformation investigation on aforementioned welded joint under maximum internal pressure of 120 bar.
Analysis of Thermal Comfort of the Building Envelope Using an Earth-Air Heat Exchanger
Authors: Soares Netto Michele , Brum Ruth da Silva , da Silva Porto Joseane , Avellaneda César Oropesa
Published: September 2024

The constructive elements of a building influence the demand for electrical energy, and optimal decisions can be assessed with the support of software that measures this building's demand more accurately. The objective of this research is to assess the thermal behavior of a residential dwelling located in bioclimatic zone 2 in the southern region of Brazil, seeking energy sources that contribute to improving thermal comfort. The study utilizes parameters that reduce the thermal demand for cooling and heating by installing an earth-air heat exchanger (EAHE) in the prolonged occupancy enviroments (POEs) within the building. The results obtained in the EnergyPlus software show that the adaptive comfort of the model with the Earth-Air Heat Exchanger (EAHE), compared to without it, reduces cold discomfort by 5.4% and increases thermal comfort in the building by 5.2%. Analyzing the annual temperatures of the spaces with the EAHE, it is observed that the outlet temperature of the EAHE duct remains at an average of 23.6°C and 23.8°C for the living room and bedrooms, respectively. From an energy perspective, the electrical energy consumption of the building was reduced by 29.8% when using the EAHE.
Numerical Simulation of Vertical Helical Earth-Air Heat Exchangers Multiobjective Performance Assessment
Authors: Razera Andre Luis , Silva Vaz Igor , Rodrigues Michel Kepes , dos Santos Elizaldo Domingues , Rocha Luiz Alberto Oliveira , Isoldi Liércio André
Published: September 2024

In the present study, a numerical evaluation of the thermal behavior of Vertical Helical Earth-Air Heat Exchangers (EAHE-VH) installations was conducted under representative climate and soil conditions of the city of Rio Grande, in southern Brazil. The Rectilinear Horizontal Earth-Air Heat Exchanger (EAHE-HR), traditionally employed, was used as a reference. The evaluated geometric variable was the pitch between the helicoids (Ph), and the performance was quantified by the thermal potential of the system, allowing for quantitative comparisons between the different EAHEs through statistical indicators. Comparisons were also made with the Vertical Earth-Air Heat Exchanger with 3 U-shaped ducts (EAHE-V3U). As a result, the option of EAHE-VH with a pitch of 100 mm achieved superior performance of up to 20 % compared to the other helical geometries studied. Additionally, it reached the result closest to the EAHE-HR considered as a reference. When compared to the EAHE-V3U, it showed lower results related to the annual thermal potential. However, it stood out for the need for a smaller volume of soil for its installation, with a reduction of 51.5 % compared to the EAHE-V3U and 79.1 % compared to the EAHE-HR. The multiobjective analysis showed the ability of the EAHE-VH to simultaneously meet the objectives related to thermal potential and required volume for installation, making it the most viable option among the evaluated EAHE construction models when both purposes are equally important.
Combating Antimicrobial Resistance: A Global Imperative and a Shared Responsibility
Authors: Samaranayake Lakshman
Published: September 2024

No abstract available
Special issue on antimicrobial resistance
Authors: Sumathipala Athula , Rajapakse Senaka , Pathmeswaran A. , Nagahawatte Ajith
Published: September 2024

No abstract available
Phenotypic and genotypic detection of carbapenem resistance and carbapenemase production in Enterobacterales isolates from cancer patients at the National Cancer Institute, Sri Lanka
Authors: Pitagampola Menu Niluthpala , Gunasekara Samanmalee Priyantha , Kapuwella Kapuwella Gamaralalage Ariyatilaka , Kottahachchi Jananie
Published: September 2024

Introduction: The emergence of pathogens that are resistant to most of the antibiotics including carba-penems are alarmingly increasing and becoming a major global threat, especially among immunocompromised patients. Presently it has become a major health chal-lenge to treat these patients as carbapenems are one of the last resort antibiotics. The main aim of this study was to detect carbapenemase production and its prevalence among Enterobacterales isolates from clinical samples of cancer patients.Methodology: Enterobacterales isolates from clinical samples received to Laboratory of Microbiology in National Cancer Institute, Sri Lanka were subjected to antibiotic sensitivity testing according to CLSI method. CarbaNP test was carried out on carbapenem non susceptible and intermediate susceptible isolates. Pathogen identification up to species level was done using the VITEK® 2 Compact system. The genotypic detection on selected isolates was carried out using the Xpert Carba-R assay.Results: The prevalence of carbapenem resistant Enterobacterales among the study isolates was 46.1%(n=48). Isolates that showed either carbapenem resistance or intermediate susceptibility (n=58) on initial testing were subjected to Carba NP test. Out of 58 carbapenem non susceptible isolates 63.8% (n=37) were positive for CarbaNP test indicating carbapenemase production. Among carbapenemase producing isolates, Klebsiella pneumoniae spp pneumoniae was found to be the most prevalent pathogen. Genetic testing on randomly selected samples showed most of them were co-harboring both blaOXA-48 and blaNDM.Conclusions: The prevalence of carbapenem resistance is notably high among cancer patients in Sri Lanka. Therefore, detecting carbapenemase-producing genes is crucial for optimizing antibiotic management. Addi-tionally, reinforcing antibiotic stewardship is necessary. Given the already high levels of carbapenem resistance, exploring and ensuring the availability of alternative treatment options within the country is essential.
Phenotypic antimicrobial resistance associated with different bla genotypes and their combinations in Enterobacterales
Authors: Perera Vindya , Samarasekara Harsha , Herath Upamali , Elvitigala Jayanthi , Chandrasiri Shirani , Corea Enoka
Published: September 2024

Introduction: Varying combinations of β-lactamase genes (bla) in Enterobacterales manifest different resistant phenotypes.Objectives: This study aimed to identify bla gene types and combinations resulting in variations in phenotypic antimicrobial resistance.Methods: Minimum inhibitory concentrations (MICs) of 75 extended spectrum β-lactamase (ESBL), AmpC β-lactamase and carbapenemase-producing Entero-bacterales isolates from a variety of clinical specimens were determined by Vitek micro-broth dilution. Bla genes were detected by 16-plex tandem PCR panel and Xpert Carba-R assay. BlaCTX-M group-1 and blaOXA-48 were the most common ESBL and carbapenemase genes, respectively.Results: Majority of the isolates (92%, 69/75) had bla gene combinations. Thirty-eight isolates (51%) carried ESBL, AmpC genes and/or narrow spectrum bla genes without any carbapenemase genes. The common bla gene combination in these isolates was blaCTX-M group-1 + blaOXA1 which is known to confer decreased susce-ptibility to piperacillin-tazobactam. Antibiotics with potential activity against ESBL-producing bacteria such as fourth generation cephalosporins, β-lactam/β-lactam-inhibitor combinations, quinolones and gentamicin also showed low rates of susceptibility. Highest susceptibility rates were to meropenem (92%) and amikacin (92%). Thirty-seven isolates (49%) carried carbapenemase genes as well. These isolates showed even higher resistance rates to all antibiotics, except amikacin (92%susceptible). Significantly higher MIC values for cefoxitin, ceftazidime, ceftriaxone, cefepime, meropenem, amikacin, tobramycin and trimethoprim-sulfamethoxazole were seen in isolates carrying blaNDM than blaOXA-48. However, a higher MIC for norfloxacin was seen in isolates with blaOXA-48.Conclusions: In conclusion, this study showed that Enterobacterales with different bla gene combinations manifest variations in phenotypic resistance to both β-lactam and non-β-lactam antibiotics.
Species distribution, antifungal susceptibility pattern and associated factors of Candida blood stream infections in Sri Lanka from 2018 to 2022
Authors: Welagedara P. G. R. Udari M. , Jayasekera Primali I.
Published: September 2024

Introduction: Candidemia can be life-threatening in immunocompromised individuals thus, prompt diag-nosis and treatment with antifungal agents is mandatory for successful outcome.Surveillance data on species distribution, antifungal susceptibility and associated factors of candidemia is utmost important to decide on empiric antifungal therapy, to impose infection control measures as well to promote antifungal stewardship in a country.Therefore, this study was aimed at retrospective review of data on candidemia at Mycology Reference Laboratory in Sri Lanka for 5 years duration to identify the species causing candidemia, their antifungal susceptibility pattern and associated factors.Results: A twofold rise in candidemia cases were seen during this 5-year duration compared to previous 7 years (2011-2017). Predominant species causing candidemia was C. tropicalis (35%) followed by C. parapsilosis (33%). C. albicans was the 3rd commonest species causing candidemia in Sri Lanka.There were 3% C. glabrata cases, 2% C. guilliermondii and 1% C. famata and C. krusei cases. Importantly two sequencing confirmed C. auris cases were identified for the first time in Sri Lanka in 2021.Overall good antifungal susceptibility was seen for both fluconazole and amphotericin B and there were only 7%and 1.6% resistance respectively.Long term hospital stay (47%) was commonly seen in this study group followed by use of broad-spectrum antibiotics (24%) and involvement of gastro-intestinal tract (21%).Conclusion: Candida tropicalis is the commonest species causing candidemia in Sri Lanka. Common Candida species had good susceptibility to antifungals. Long term hospital stay was associated with candidemia in majority of patients.
Assessing the efficacy of empiric antibiotic therapy for selected infections in patients with and without malignancy
Authors: Chathuranga Gayashan , Dissanayake Thushari , Fernando Neluka , Wanigatunge Chandanie Amila
Published: September 2024

Introduction: Guidelines for the selection of empirical antibiotics aim to improve patient outcomes, reduce unnecessary antibiotic use and reduce development of antimicrobial resistance.Objectives: To assess the adherence to guidelines for the selection of parenteral empirical antibiotics for three infections in patients with and without malignancies, to determine whether the national guidelines reflect the current bacterial susceptibility patterns of selected infections, and to determine the appropriateness of the selected parenteral empirical antibiotics for the selected infections.Methods: The study included bacterial isolates from adults with and without malignancy who had a positive culture for lower respiratory tract infection, skin and soft tissue infection, or urinary tract infection, and who were prescribed parenteral empirical antibiotic. Antibiotic susceptibility was determined by standard micro-biological methods. Adherence to guidelines was defined as prescribing the empiric antibiotic concordant with national guidelines.Results: The analysis included 155 bacterial isolates from each population. The selection of empirical antibiotics was guideline-concordant in 92.4% without and 67.5% with cancers. Resistance to recommended empirical antibiotics was seen in 29.5% and 41.2% of the bacterial isolates in those without and with cancers respectively. Only 47.5% and 20.6% of isolates from those without and with cancers respectively were sensitive to the empirical antibiotic prescribed and therefore considered as appropriate antibiotic prescriptions.Conclusions: Empirical antibiotic guidelines should be updated to reflect the prevailing bacterial sensitivity patterns to ensure optimum outcomes. Prescribing pat-terns and guideline concordance should be periodically evaluated to ensure that the antimicrobial stewardship programs are moving in the right direction.
Impact of bacteraemia caused by third-generation cephalosporin non-susceptible Enterobacteriaceae – a cohort study
Authors: Sucharitharathne Manushi Pamoda , Kolambage Yasas Dahamuna , Jayatilleke Sashika Kushlani
Published: September 2024

Introduction: Bacteraemia caused by Enterobacteriaceae poses a significant threat to hospitalized patients, with rising rates of resistance to third-generation cephalo-sporins (3GC) complicating treatment efficacy. This is the first study done in Sri Lanka to assess the impact of 3GC resistance in bacteraemia patients.Objective: The aim was to study the impact of 3GC non-susceptibility on outcomes in patients with Entero-bacteriaceae bacteraemiaMethods: This is a retrospective cohort study, conducted at Sri Jayewardenepura General Hospital in Sri Lanka. Patients who had bacteraemia with Enterobacteriaceae from March 2022 to April 2024 were included. Data were collected from hospital medical records and laboratory data and by calling the patient or caregiver.Results: Of the 335 cases identified, 59.4% were bacteraemia with 3GC non-susceptible Enterobac-teriaceae (3GCNSE). Patients with 3GCNSE tended to be older with more comorbidities, and urinary infections were predominant in both groups. E. coli and K. pneumoniae exhibited high resistance rates. Significant differences were observed in 7, 14, and 30-day all-cause mortality rate, healthcare cost, and duration of hospital stay between the two cohorts. However, in regression analysis, 3GCNSE were more likely to increase healthcare cost and, underlying chronic liver disease significantly increased the severity of illness and mortality rates.Conclusions: As nearly 60% of the bacteraemia caused by Enterobacteriaceae were 3GCNS, healthcare cost was higher when managing such patients, this highlights the economic burden of antimicrobial resistance (AMR). Therefore, it is important to control the AMR in lower-middle income countries such as Sri Lanka.
Synchronized Flow Control of Dynamic Stall under Coupled Pitch and Freestream Oscillations
Authors:   The Ohio State University, Bons Jeffrey , Frankhouser Matthew , Gregory James
Published: September 2024

This work presents results of an experimental investigation into synchronized active flow control of a Sikorsky SSC-A09 airfoil undergoing periodic pitching motion in an unsteady free stream using leading edge blowing. The airfoil was evaluated at reduced pitching frequencies up to k=0.05 at steady Mach numbers of 0.2 and 0.4, and at k=0.025 with phase-locked pitch and Mach oscillations at Mach 0.4±0.07 at Reynolds numbers from 1.5 to 3 million. A spanwise row of vortex generator jets (VGJs) located at 10% chord is fed by an oscillating valve that is phase-locked to the pitch oscillation of the airfoil. The oscillating valve can be set to produce a peak jet mass flux ratio (Cq) of 0.0022 or 0.0028 with a background Cq of half this value over the remainder of the period. The phase and duration of the peak Cq were varied to optimize the flow control benefits to both CL and CM hysteresis loops and reduce negative damping. Peak performance was observed with actuation initiated just after lift stall and continuing for 11% of the pitch cycle. Blowing beyond 11% resulted in no perceptible benefit. Compared to steady blowing flow control, the 11% synchronized control case delivers comparable (or better) performance with less than 50% of the massflow. The degree of stall control is a function of reduced frequency, mass flux ratio, and Mach number.
Line-Based Unstructured/Structured Heterogenous CPU/GPU Framework for Complex Aerodynamic Flows
Authors:   University of Maryland, Jung Yong , Jude Dylan , Govindarajan Bharath , Baeder James
Published: September 2024

A heterogeneous solution infrastructure using both CPU and Graphics Processing Units (GPU) is presented for threedimensional aerodynamic flows on overset meshes. A line based solver on unstructured grids on CPU (HAMSTR) is coupled to a structured RANS solver on GPUs (GARFIELD) through a lightweight Python-based framework. In HAMSTR, "linelets" through the meshes are found in a robust manner and the solver uses line-implicit schemes and high-order reconstruction schemes along these linelets, similar to a structured solver. This methodology is extended to pure unstructured volume grids, to enable solution in complex geometries. Mesh deformation techniques are implemented using a spring analogy to solve for deforming meshes. The GPU solver GARFIELD can operate in an overset environment and shows competitive speedups when compared to well-established structured solvers. The solvers are integrated through a mesh connectivity tool (TIOGA) and are individually demonstrated for cases such as hovering rotor and a rotor in forward flight. Aerodynamic flow past a rotor hub was simulated using the solution framework and the predictions in unsteady drag and spectral components of the drag agreed reasonably well with experiments and other CFD simulations.
Personal Rotorcraft Design and Performance with Electric Hybridization
Authors:   NASA Glenn Research Center, Snyder Christopher
Published: September 2024

Recent and projected improvements for more or all-electric aviation propulsion systems can enable greater personal mobility, while also reducing environmental impact (noise and emissions). However, all-electric energy storage capability is significantly less than present, hydrocarbon-fueled systems. A system study was performed exploring design and performance assuming hybrid propulsion ranging from traditional hydrocarbon-fueled cycles (gasoline Otto and diesel) to all-electric systems using electric motors / generators, with batteries for energy storage and load leveling. Study vehicles were a conventional, single-main rotor (SMR) helicopter and an advanced vertical takeoff and landing (VTOL) aircraft. Vehicle capability was limited to two or three people (including pilot or crew); the design range for the VTOL aircraft was set to 150 miles (about one hour total flight). Search and rescue (SAR), loiter, and cruise-dominated missions were chosen to illustrate each vehicle and degree of hybrid propulsion strengths and weaknesses. The traditional, SMR helicopter is a hover-optimized design; electric hybridization was performed assuming a parallel hybrid approach by varying degree of hybridization. Many of the helicopter hybrid propulsion combinations have some mission capabilities that might be effective for short range or on-demand mobility missions. However, even for 30 year technology electrical components, all hybrid propulsion systems studied result in less available fuel, lower maximum range, and reduced hover and loiter duration than the baseline vehicle. Results for the VTOL aircraft were more encouraging. Series hybrid combinations reflective of near-term systems could improve range and loiter duration by 30%. Advanced, higher performing series hybrid combinations could double or almost triple the VTOL aircraft's range and loiter duration. Additional details on the study assumptions and work performed are given, as well as suggestions for future study effort.
Probabilistic Methodology for Multi-Fidelity Model-Based Robust Preliminary Design of Rotorcraft
Authors:   Technical University of Munich, Wirth Dominik , Hajek Manfred
Published: September 2024

A novel methodology for the robust preliminary design of rotorcraft is presented. The methodology is model-based as opposed to empirically driven. A systems-engineering-inspired mindset is followed, manifesting in a hierarchical approach to both design and modeling. The sources of uncertainty in a model-based design environment are discussed. A concept to cope with these uncertainties in the context of preliminary design is presented. The hierarchical multifidelity modeling strategy is depicted, after which the importance of a methodical and traceable model development strategy across model fidelity levels is pointed out. A corresponding probabilistic approach is presented. A method of merging these elements into a coherent methodology for robust preliminary design is outlined. A demonstration of the developed methodology is subsequently conducted by applying this methodology to a fictive preliminary design problem. Ultimately, a discussion of the methodology is given based on the obtained results. The viability of the methodology for quantifying and controlling the model-related uncertainty prevalent in model-based preliminary design is successfully demonstrated.
Design of Small Rotors for Multicopter UAS
Authors:   US Army Research Laboratory, Beals Nathan
Published: September 2024

Numerical optimizations of small rotors for multicopter UAS are presented using blade element momentum theory as the objective function. Total power required is minimized by allowing the chord distribution, twist distribution, and rotor rotational speed to vary subject to several geometric and performance constraints. The region of the global minimum of the objective function is found using the non-gradient-based genetic algorithm NSGA-II, at which point a gradient-based method is used to refine the solution. Two design cases are presented. The first is for sea-level hover of a nine inch diameter rotor intended for use on small multicopter UAS. The second is for high-altitude hover of a larger rotor. Optimized designs for the first case operating at the same thrust required twenty-nine percent less power than a baseline rotor. The power savings associated with a large maximum allowable chord length is found to be very small.
Open Ethernet-Based Embedded Platforms for Integrated Modular Architectures and Autonomous Systems
Authors:   TTTech Computertechnik AG, Jakovljevic Mirko ,   TTTech North America, Soares Alvaro
Published: September 2024

By adopting the latest developments from other critical (e.g. integrated modular avionics) and high-volume automotive industries with safety requirements (ADAS and autonomous driving), the rotorcraft industry could reduce system lifecycle costs and gain new integrated platform capabilities which support incremental modernization, simplify upgrades and modifications for different missions or rotorcraft platforms. A specific set of architecture design patterns and computational models, used in integrated modular architectures, enables the design of less complex integrated systems which can collect and process all system sensor data in (hard) real-time, supports seamless sensor data fusion for IVHM, and enables the integration of critical and non-critical functions. Accompanied with robust system engineering, RTCA DO-254 / DO-178C DAL A/B design assurance and extended use of ASIL-D-compliant (automotive) components, novel integrated architectures for rotorcraft can be designed to fit with robust modular form factors such as VPX. Such integrated architectures can be extended with COTS computing and sensor fusion LRUs/ECUs used for automotive ADAS/ADS (advanced driver assistance systems/autonomous driver systems) and rapidly progressing autonomous driving applications.
Characterization of Pilot Technique
Authors:   US Army ADD, Bachelder Edward ,   NASA Ames Research Center, Aponso Bimal , Godfroy Martine
Published: September 2024

Skilled pilots often use pulse control when controlling higher order (i.e. acceleration-command) vehicle dynamics. Pulsing does not produce a stick response that resembles what the human Crossover Model (Ref.1) predicts. The Crossover Model (CM) assumes the pilot provides compensation necessary (lead or lag) such that the suite of display-human-vehicle approximates an integrator in the region of crossover frequency. However, it is shown that the CM does appear to drive the pilots' pulsing behavior in a very predictable manner. Roughly speaking, the pilot generates pulses such that the area under the pulse (pulse amplitude multiplied by pulse width) is approximately equal to area under the hypothetical CM output. This can allow a pilot to employ constant amplitude pulsing so that only the pulse duration (width) is modulated - a drastic simplification over the demands of continuous tracking. A pilot pulse model is developed, with which the parameters of the pilot's internally-generated CM can be computed in real time for pilot monitoring and display compensation. It is also demonstrated that pursuit tracking may be activated when pulse control is employed.
Performance and Loads Study of a High-Speed Compound Helicopter
Authors:   Science and Technology Corporation - Ames Research Center, Bowen-Davies Graham ,   US Army ADD - AvMC, Yeo Hyeonsoo
Published: September 2024

An aeromechanics analysis was conducted of a large-winged, single main rotor, compound helicopter modified from the AH-56 Cheyenne, in cruise and high-speed flight (250 knots) at sea level and high altitude (20,000 ft.) conditions. Performance and representative loads were evaluated with the comprehensive code RCAS to show the effect of compound configuration decisions. Suitability of the analysis for high advance ratio predictions was demonstrated through comparison to the UH-60A slowed rotor test data, and validation of compound performance prediction was shown with AH-56 Cheyenne test data. An assessment of the role of compound configuration, collective setting, wing pitch, rotor speed, altitude and trim control strategy on performance and loads was made. The study shows how reducing collective, for a constant wing pitch, is beneficial for peak L=De and reducing loads. Increasing wing pitch, at a constant collective, improves peak L=De, but can reduce L=De at high airspeeds and limit maximum airspeed. A 30% reduction in rotor speed achieved significant performance increases, while larger reductions limited high airspeed and high altitude trim due to stall. High altitude flight improves L=De at all airspeeds if stall on the prop rotor can be prevented. Ailerons and horizontal stabilizer trim control does not adversely affect L=De, but free rotor cyclics to trim for reduced flap bending loads. Interference effects from the rotor on the wing reduced peak L=De, but the effect is marginal above 170 knots. The final compound configuration achieved a peak L=De = 7.6 around 140 knots and L=De > 5.0 at the maximum airspeed considered of 250 knots. The static control derivatives for the compound showed less authority than a conventional helicopter, however increasing control authority is shown across the flight envelope.
High-fidelity, 3D Stress Prediction for Composite Rotor Blades
Authors:   University of Maryland, Han Shilei , Bauchau Olivier
Published: September 2024

An accurate knowledge of the complete three-dimensional stress field is a prerequisite to the design of low maintenance composite rotor blades. The paper focuses on the development of an efficient methodology for computing three-dimensional stress distributions in helicopter rotor blades. The proposed methodology is based on theoretical developments that allow the determination of exact solutions of three-dimensional elasticity solutions for beams of arbitrary cross-sectional geometry and made of anisotropic composite materials. The effects of curvature, distributed loading, and higher-order strains can also be taken into account. The approach has been implemented in a finite element code, SectionBuilder, which generates two-dimensionalmeshes for cross-sections presenting complex geometries and material distributions and evaluates the sectional stiffness properties and three-dimensional stress distributions in the cross-sections. Because it is based on a parametric definition of the cross-section, SectionBuilder facilitates the modeling and analysis process of composite rotor blades and it can be used as a pre- and post-processor of comprehensive analysis codes.
Optimization of Circular Force Generator Placement for Rotorcraft Hub Force and Moment Cancellation
Authors:   The Pennsylvania State University, Prakash Keerti , Lesieutre George
Published: September 2024

High-speed forward flight in helicopters causes high vibratory loads at the rotor hub, which are transmitted into the fuselage. This results in pilot fatigue and high maintenance requirements. Anti-vibration devices or vibration absorbers may be placed near the hub to reduce vibration transmission, while active vibration control systems may typically sense and reduce forces in specific areas of the fuselage. This paper focuses on developing strategies for optimal deployment (sizing, placement and control) of Circular Force Generators (CFGs) for vibration cancellation. Particle Swarm Optimization was used to carry out the optimization for two different load cases corresponding to different flight conditions. Converged solutions for CFG placement were obtained for: different individual load cases; multiple load cases; constrained and unconstrained actuator locations; and using different numbers of actuators. Two CFGs were found to be sufficient to cancel hub loads for a single load case. When two load cases are considered in multi-objective optimization, three actuators can substantially cancel the hub loads (to within 1%). And using four actuators can cancel the hub loads to within 0.1%. Finally, performance under actuator failure was considered as a way to distinguish among otherwise similarly-performing placement solutions.
Capability for Fully Integrated Aeroelastic Simulation of Complete Vertical Lift Configurations
Authors:   ATA Engineering Inc., Reveles Nicolas ,   Georgia Institute of Technology, Bern Noah , Blades Eric , Smith Marilyn
Published: September 2024

A framework for the fully integrated simulation of aeroelastic rotors and fuselages has been developed to capture the entire range of interactional vibratory loads that arise in a rotorcraft. The framework adds fixed-frame fuselage fluid-structure interaction and rotor/fuselage structural coupling capabilities to well-established rotor CFD/CSD methods. The solution methods utilized for the fuselage structural dynamics response are detailed. The effects of compliance on the rotor/fuselage interface are examined for the structural coupling. It is observed that startup transients excite the fuselage structural response and are slow to decay, so an approach to accelerate the convergence of structural dynamics in periodic flight conditions is examined. Identification of the coupled effects on fuselage vibrations are investigated by partially decoupling the framework. Further development of the framework is warranted to extend the coupling options and support alternative solvers.
Parameter Optimization of Dynamic Inversion Control Laws for Shipboard Operations
Authors:   The Pennsylvania State University, Horn Joseph ,   Advanced Rotorcraft Technologies, Lee Dooyong , Yang Junfeng , He Chengjian
Published: September 2024

Two approaches to gains optimization of dynamic inversion control laws have been developed to facilitate the shipboard operation of rotorcraft. The first approach is a frequency-based method to optimize the tradeoff between stability margins and disturbance rejection properties; the second approach uses direct optimization of gains to enhance tracking performance in the time domain. Comparative studies show that both methods tend to use high gain design for improvement of tracking error while rejecting airwake disturbances and following station-keeping commands over a moving deck. The frequency domain based method provides firm information on the margin to instability, although this is done via analysis of each axis independently. The direct optimization approach directly addresses tracking error performance in all axes, but the method resulted in only moderate improvements over the baseline gains for the particular case studied.
Handling Qualities Assessment of a Pilot Cueing System for Autorotation Maneuvers
Authors:   Georgia Institute of Technology, Rogers Jonathan ,   The University of Liverpool, Jump Michael , Strickland Laura , Repola Caroline , Cameron Neil , Fell Thomas
Published: September 2024

This paper details the design and limited flight testing of a preliminary system for visual pilot cueing during autorotation maneuvers. The cueing system is based on a fully-autonomous, multi-phase autorotation control law that has been shown to successfully achieve autonomous autorotation landing in unmanned helicopters. To transition this control law to manned systems, it is employed within a cockpit display to drive visual markers which indicate desired collective pitch and longitudinal cyclic positions throughout the entire maneuver, from autorotation entry to touchdown. A series of simulator flight experiments performed at University of Liverpool's HELIFLIGHT-R simulator are documented, in which pilots attempt autorotation with and without the pilot cueing system in both good and degraded visual environments. Performance of the pilot cueing system is evaluated based on both subjective pilot feedback and objective measurements of landing survivability metrics, demonstrating suitable preliminary performance of the system.
Development and Simulation Testing of High-Speed Evasive and Attack MTEs for Rotorcraft Handling Qualities Evaluation
Authors:   Sikorsky Aircraft Corporation, Fegely Cody ,   US Army RDECOM, Carl LTC , Fell William , Xin Hong , Blanken Chris
Published: September 2024

The Vertical Lift Consortium (VLC)\National Rotorcraft Technology Center (NRTC) project, "Rotorcraft Handling Qualities Requirements for Future Configurations and Missions" is a U.S. Government and industry co-funded research project intended to develop mission task elements (MTEs) to ensure desired handling qualities of high-speed rotorcraft are achieved. These new high-speed tasks must fit into the mission-oriented approach already established by ADS-33E-PRF. The work presented in this paper summarizes the development and simulation testing of two new high-speed MTEs, one attack and one evasive. These new MTEs, Ground Attack and Break Turn, were developed from fixed-wing and rotorcraft handling specifications and papers. Four aircraft configurations were used to evaluate the ability of the Ground Attack and Break Turn MTEs to identify known handling qualities deficiencies. The results of the evaluation showed the Ground Attack and Break Turn MTEs are suitable tasks for assessing rotorcraft handling qualities in high-speed forward flight. The handling qualities ratings (HQRs) obtained from the Ground Attack and Break Turn MTEs were within ±1 HQR of the Depart/Abort and Slalom MTEs for each configuration evaluated. The agreement of the HQRs among the different MTEs indicated the new proposed MTEs were able to detect the known handling qualities deficiencies to the same level as the current ADS-33E-PRF MTEs but at a higher forward flight speed.
Historical Overview of the Civil Aerospace Medical Institute's Biodynamics Facility
Authors:   Federal Aviation Administration, Taylor Amanda , DeWeese Richard
Published: September 2024

This is a general summary of over fifty years of crashworthiness programs previously conducted, currently ongoing, and proposed for future accomplishment at the Federal Aviation Administration's (FAA) Civil Aerospace Medical Institute's (CAMI) Biodynamics Research Laboratory. The research facility focuses on occupant impact protection technology, which includes the seating system, supporting floor structures, restraint systems, and cabin interior components that an occupant might physically contact during an emergency landing.
An Interview with General Richard A. Cody: The Soldiers' General and His Enduring Impact on Army Aviation
Authors:   US Army (Ret.), Fardink Paul
Published: September 2024

The Army Aviation Hall of Fame states that "No individual has had a greater impact on the Army and the Aviation Branch" than General Richard Cody. After receiving his commission in 1972 at West Point, Cody served with distinction for 36 years until retiring as the Army's 31st Vice Chief of Staff in 2008. While still a Lieutenant Colonel, in 1991 he led his Apache battalion into Iraq to fire the first shots of Operation DESERT STORM, eliminating critical enemy radar sites before the air war campaign even began. In the years following September 11, 2001, as Deputy Chief of Staff for Operations (G-3/5/7) and then as Vice Chief of Staff, his efforts led to the most sweeping transformation the Army and the Aviation Branch had ever seen. An ace special operations pilot and brilliant military mastermind, General Cody may best be remembered, however, as the well-loved "Soldiers' General."
Simulation of Spiral Bevel Gear Tooth Manufacturing to Aid in One Piece Gear Shaft Design
Authors:   The Boeing Company, Davidson Scott , Pierce Christopher
Published: September 2024

Many spiral bevel gear applications are implemented with a two piece gear where the gear and shaft are bolted or inertia welded as an assembly task. Eliminating a bolted, splined, or welded joint between the spiral bevel gear and shaft can reduce complexity and cost in a transmission design. Simulations of the motion of spiral bevel machine tools have been developed to ensure successful integral shaft designs for helicopters. Awareness of the location of the wheel during spiral bevel gear tooth manufacturing enables a design solution to iterate between the gear shaft and spiral bevel gear tooth design. The simulation was revisited to refine a preliminary two dimensional tool as well as create a more detailed three dimensional visualization for use during the design process. The design process was applied to three helicopter bevel gear designs. Physical verification was completed on two designs as a risk reduction in the bevel gear grinding machine before the design was released to manufacturing. The tools used in the design process as well as verification during manufacturing are discussed in this publication for three different integral shaft spiral bevel gears for helicopters.
Analysis of Motion Parameter Variations for Rotorcraft Flight Simulators
Authors:   German Aerospace Center (DLR), Jones Michael ,   University of Liverpool, White Mark , Barnett Miles , Fell Thomas
Published: September 2024

No standard guidelines currently exist for tuning rotorcraft flight simulation motion platforms. This often leads to systems that are poorly utilized. This paper presents results from a study to determine the influence of parameter variations in two rotorcraft research simulators. Investigations were conducted using three Mission Task Elements (MTEs), and both subjective and objective analysis is used to determine the suitability of motion settings. Motion settings are compared with recommended Objective Motion Cueing Test (OMCT) boundaries for fixed-wing aircraft. Results show differences in the fidelity of motion settings, and recommendations specifically for rotorcraft simulation are presented.
Extending the Objective Motion Cueing Test to Measure Rotorcraft Simulator Motion Characteristics
Authors:   Delft University of Technology, Dalmeijer Wouter , Miletovic Ivan , Stroosma Olaf , Pavel Marilena
Published: September 2024

In search of a more objective way to evaluate motion cueing fidelity, the Objective Motion Cueing Test (OMCT) was proposed by Advani and Hosman in 2006. However, a direct application of this test for rotorcraft flight simulation has not yet been studied. The first objective of this paper is therefore to investigate the extent to which the OMCT is representative for rotorcraft simulation. The second objective is to investigate whether the OMCT can be extended to better represent helicopter motion. It was found that the current OMCT defines a set of input signals that is sufficient for predicting simulator heave motion characteristics, but might not be representative for predicting simulator pitch and surge motion characteristics in rotorcraft flight simulation. Using an extended OMCT initially tailored to only longitudinal helicopter motion, notable differences in predicted simulator pitch and surge motion characteristics were found between configurations that the original OMCT considered equal. Comparing data from a pilot-in-the-loop experiment performed on the SIMONA Research Simulator (SRS) with off-line automated flights, it was found that the methodology can reliably expose trends in motion fidelity changes without having to rely on piloted simulator data. An initial attempt to validate the predicted fidelity changes with pilot ratings was not successful, but further experimentation with this methodology on the SRS is planned.
The Use of Pilot Ratings in Rotorcraft Flight Simulation Fidelity Assessment
Authors:   Delft University of Technology, Miletovic I. ,   Desdemona B.V., Wentink M. , Pool D. , Stroosma O. , Pavel M. , Wentink M. , Mulder M.
Published: September 2024

The fidelity of a rotorcraft flight simulator is influenced by many factors, such as the vehicle dynamic model and the motion cueing algorithm (MCA). To quantify the fidelity of a simulator objectively requires detailed knowledge of human pilot perception and control behaviour that is not yet available. As a consequence, subjective assessments made by qualified pilots remain the most important way to assess flight simulation fidelity. The use of standardized rating scales during such assessments can increase the level of objectivity above that provided by less structured evaluations. The current paper describes the result of an experiment performed on the Desdemona simulator to evaluate two rating scales, namely the Simulator Fidelity Rating (SFR) scale and the Motion Fidelity Rating (MFR) scale, as suitable indicators of flight simulation fidelity. In this experiment, two characteristics of the simulated environment were varied, namely rotorcraft dynamics and MCA configuration, and the type of rating scale used was treated as an additional independent variable. The primary results of the experiments suggest that pilots are able to recognize a strong decline in flight simulation fidelity when both rotorcraft dynamics and motion are degraded simultaneously. However, when either one of these characteristics are varied independently of the other, the results are inconclusive. The paper presents a more detailed review of the various results gathered during the experiment and formulates recommendations for future experiments in rotorcraft flight simulation fidelity assessment that involve the use of pilot ratings.
Shape Sensing and Structural Health Monitoring of Rotor Blades from Strain Analysis
Authors:   Universita Tre Roma, Bernardini Giovanni ,   Politecnico di Milano, Masarati Pierangelo , Porcelli Roberto , Serafini Jacopo
Published: September 2024

This paper presents an original combined approach to shape-sensing and structural health monitoring of helicopter rotors. It is based on the measurement of strain in a limited number of points over the blade surface. The Shape-Sensing algorithm is modal-based and capable of reconstructing nonlinear, moderate lag, flap and torsion deflections. Two Structural Health Monitoring algorithms are presented, one in the time domain and the other in the frequency domain. Both are based on the analysis of the discrepancies between the strains arising in the damaged and the undamaged blades. Two damage types have been considered: a mass unbalance and a localized stiffness reduction. Both Shape Sensing and Structural Health Monitoring capabilities have been tested by numerical simulation using a multibody dynamic solver for general nonlinear comprehensive aeroelastic analysis.