bluuebunny/crossref_metadata_2025 huggingface dataset:
A Hybrid Damage Modeling and Experimental Study of Composite Tee-joints under Pull-off Loading
Authors:   Global Engineering and Materials Inc., Cui Xiaodong ,   Wichita State University, Seneviratne Waruna ,   Naval Air Warfare Center (PAX), Phan Nam , Ren Xiang , Lua Jim
Published: September 2024

It is a great challenge to perform an accurate and efficient fatigue life prediction of a bonded composite structure with the presence of geometry and material heterogeneity induced stress concentration. The present fatigue damage characterization of composite structures is still dominated by the use of a phenomenological stress-life (S-N) approach due to the availability of extensive S-N data and lower cost in generation of S-N data from fatigue tests at different applied stress ratios. Because of the inaccurate life prediction using the S-N approach for the structure with stress concentrators, a more rational fracture mechanics approach based on a Paris type crack growth law can be applied to compute the crack growth driving force provided that an initial flaw has to be introduced. In order to simulate both the crack initiation and propagation, a dual spring model is implemented at each nodal point where the static failure is simulated using springs of a cohesive type material model while fatigue crack propagation is calculated using springs of an elastic penalty stiffness coupled with a virtual crack closure technique (VCCT). In order to validate the dual spring model for the fatigue damage prediction, two types of Tee-joints are fabricated and tested by the National Institute for Aviation Research (NIAR) with and without a Teflon insertion. A calibration analysis is performed to determine the fatigue crack growth parameters using Tee-joints with a Teflon insert followed by the blind fatigue prediction of the specimens without a Teflon insert.
Low-Speed Wind Tunnel Drag Test of a 2/5 Scale AH-56 Cheyenne Door-Hinge Hub
Authors:   US Army Aviation Development Directorate, D. Robert , Nuñez Gerardo
Published: September 2024

The Aviation Development Directorate of the U.S. Army Aviation and Missile Research, Development and Engineering Center (AMRDEC) conducted a drag test of a non-rotating 2/5 scale Lockheed AH-56 Cheyenne main rotor hub in the U.S. Army 7- by 10-foot Wind Tunnel located at NASA Ames Research Center in Moffett Field, CA. The purpose of the test was to quantify the drag reduction on the Cheyenne's unique "door-hinge" style hub when the mechanical control gyro is removed, with the implicit assumption that the control and stabilization functions of the gyro could be replaced by a modern flight control system located somewhere within the aircraft’s outer mold line. The model was tested in a number of non-rotating configurations, orientations, and tunnel conditions. Baseline results compared favorably with historical drag measurements, and showed approximately a 50% reduction in hub drag with the gyro removed, with an additional 10% reduction due to rudimentary streamlining of the bluff outer hub arm.
Wind Tunnel Testing for the SB>1 Defiant Joint Multi-Role Technology Demonstrator
Authors:   Sikorsky a Lockheed Martin Company, Lorber Peter ,   United Technologies Research Center, Bowles Patrick ,   The Boeing Company, Fox Eric , Wang Zhe , Hein Benjamin , Mayrides Bryan
Published: September 2024

Wind tunnel tests have been conducted to support development of the SB>1 DEFIANT™ Joint Multi-Role Technology Demonstrator. The objective is to provide data to validate and enhance the aerodynamic performance and flight dynamics models and to improve understanding of the aerodynamics of X2 TECHNOLOGY™ configurations. The first model was a 1/11 scale airframe with a powered propeller that was tested in the United Technologies Research Center (UTRC) Pilot Wind Tunnel (PWT) in 2013-2014. The second model was a 1/5 scale airframe with a powered coaxial main rotor that was tested at the U.S. Air Force National Full Scale Aerodynamic Complex (NFAC) in 2016. This model could also be tested with a powered propeller. Measurements included forces and moments on the various components, as well as fuselage, empennage, and blade surface pressures. For the 1/11 model, fuselage-induced flow fields at the propeller and empennage locations were also measured. Application of the experimental results to the State Space GenHel flight dynamics model is described.
Structural and Flight Test of a Composite Bubble Door for the CHI CH-47D
Authors:   Columbia Helicopters Inc., Pilkington Lawrence , Solem Courtney , Royce Anna
Published: September 2024

Columbia Helicopters, Inc, (CHI) has procured several military-surplus CH-47D helicopters for use in heavy-lift operations, including fire-fighting and other external lift operations. For decades, CHI has successfully utilized Direct Visual Operational Control (DVOC) to precisely control the load at the end of a long line. The key to DVOC is the use of a bubble window at both pilot and co-pilot positions on the aircraft, which allows the pilot flying the aircraft to see the load directly. CHI designed, manufactured, tested, and qualified a replacement cockpit door to hold a bubble window in the CH-47D. The new doorframe is made of carbon-fiber epoxy composite, holds an 18-inch-deep bubble window in the upper section, and holds a sliding ventilation window in the lower section. An abbreviated composite building block test was completed to prove the structure, and flight test was used to determine the optimal flight attitude to evacuate the cockpit of smoke.
Modeling, Analysis, and Optimization of Rotorcraft and Fleet Availability
Authors:   University of Massachusetts, Bhattacharya Salkath ,   US Army Research Laboratory, Spero Eric , Nagaraju Vidhyashree , Jafary Bentolhoda , Katipally Karthik , Fiondella Lance , Ghoshal Anindya
Published: September 2024

The availability of a rotorcraft fleet to fulfill missions is driven by the size of the fleet, time-varying mission demand profile, average mission duration, inspection and maintenance times as well as other factors impacting the logistics and supply chain. Traditional availability measures such as the steady state availability and transient availability lack the expressivity needed to determine the probability that a specified fleet size and supporting maintenance staff will be able to ensure a mission can be initiated at a specified point in time given an anticipated mission profile. In the absence of sufficiently robust modeling and analysis techniques, it is also difficult to determine how rotorcraft reliability and maintenance process improvements could be implemented to enhance traditional and extended notions of rotorcraft and fleet availability. This paper presents methods to model and assess the impact of subsystem reliability investment on rotorcraft availability. We also extend traditional availability concepts to the case of on-demand availability, where availability is characterized as a time-varying function of the demand for a fleet of rotorcraft. The examples illustrate that the approach can be used to consider tradeoffs between on-demand availability and factors such as fleet size and maintenance times.
Robust Hydraulic Filter Rated Using Dynamic Efficiency Test Method Will Increase Aircraft Reliability and Safety
Authors:   US Army - Aviation Engineering Directorate, Rao Peter
Published: September 2024

Hydraulic contamination is a major contributor to flight control anomalies, binding, and leakage of hydraulic components. Typically, filters are rated using Beta Ratio/Efficiency at certain micron sizes per standard lab tests such as ISO 16889 or Mil-F-8815D (Ref. 1, 2). These are all steady flow tests at 100°F. Unfortunately, during normal aircraft operations, hydraulic filters are exposed to a wide range of operating conditions such as high oil temperatures, vibration due to pressure pulsations and flight maneuvers, cyclic flow and thermal excursions. The current hydraulic filters used on Army helicopters tend to shed particles during cyclic flow and vibration which can cause close clearance spools to lock-up in servo controls. This may result in un-commanded flight control inputs. This can also result in low Mean Time Between Failures (MTBF) on pumps and actuators. The US Army has developed new hydraulic filter specifications which require dynamic test procedures using more realistic conditions. This has resulted in the development of more robust media filters, which have been shown during on-aircraft demonstrations to increase fluid cleanliness and decrease maintenance costs.
Identification of Spurious Signals from Permeable Ffowcs Williams and Hawkings Surfaces
Authors:   NASA Langley Aeroacoustics Branch, Lopes Leonard ,   Analytical Services and Materials, Wiedemann Karl , Douglas D. , Nark Douglas
Published: September 2024

Integral forms of the permeable surface formulation of the Ffowcs Williams and Hawkings (FW-H) equation often require an input in the form of a near field Computational Fluid Dynamics (CFD) solution to predict noise in the near or far field from various types of geometries. The FW-H equation involves three source terms; two surface terms (monopole and dipole) and a volume term (quadrupole). Many solutions to the FW-H equation, such as several of Farassat's formulations, neglect the quadrupole term. Neglecting the quadrupole term in permeable surface formulations leads to inaccuracies called spurious signals. This paper explores the concept of spurious signals, explains how they are generated by specifying the acoustic and hydrodynamic surface properties individually, and provides methods to determine their presence, regardless of whether a correction algorithm is employed. A potential approach based on the equivalent sources method (ESM) and the sensitivity of Formulation 1A (Formulation S1A) is also discussed for the removal of spurious signals.
Investigation of Rotor-Airframe Interaction Noise Associated with Small-Scale Rotary-Wing Unmanned Aircraft Systems
Authors:   NASA Langley Research Center, Zawodny Nikolas , Douglas D.
Published: September 2024

In this study, hover acoustic measurements are taken on isolated rotor-airframe configurations representative of smallscale, rotary-wing unmanned aircraft systems (UAS). Each rotor-airframe configuration consists of two fixed-pitch blades powered by a brushless motor, with a simplified airframe geometry intended to represent a generic multicopter arm. In addition to acoustic measurements, CFD-based aeroacoustic predictions are implemented on a subset of the experimentally tested rotor-airframe configurations in an effort to better understand the noise content of the rotor-airframe systems. Favorable agreements are obtained between acoustic measurements and predictions, based on both time- and frequency-domain post-processing techniques. Results indicate that close proximity of airframe surfaces result in the generation of considerable tonal acoustic content in the form of harmonics of the rotor blade passage frequency (BPF). Analysis of the acoustic prediction data shows that the presence of the airframe surfaces can generate noise levels either comparable to or greater than the rotor blade surfaces under certain rotor tip clearance conditions. Analysis of the on-surface Ffowcs Williams and Hawkings (FW-H) source terms provide insight as to the predicted physical noise-generating mechanisms on the rotor and airframe surfaces.
Performance Measurements of UAV-Scale Cycloidal Rotor
Authors:   Texas A&M University, Kellen Adam , Benedict Moble
Published: September 2024

This paper focuses on systematic time-averaged performance measurements of a cycloidal rotor operating at Reynolds numbers between 100,000 and 300,000. Cycloidal rotor is a revolutionary horizontal axis propulsion device that has proven to benefit from increased maneuverability and aerodynamic efficiency at micro air vehicle (MAV) scales. The current study aims to characterize the performance of a cycloidal rotor at significantly larger UAV-scales. Towards this, a three-component balance was custom built to measure the vertical thrust, sideward thrust and torque of a 3.5 ft diameter cycloidal rotor. Experiments were conducted for a range of rotational speeds across different blade pitch amplitudes for both 2- and 4-bladed cycloidal rotor configurations. Higher Reynolds numbers associated with operation and a lower chord/radius ratio led to a reduction in the relative magnitude of the sideward thrust when compared to MAV scales and hence, a smaller tilt of the resultant thrust from the vertical. Examination of the effect of blade pitch amplitude showed an optimal pitch amplitude of ±30° for both the 2- and 4-bladed rotor configurations. This optimal pitch amplitude is significantly lower than what was previously determined for MAV scale cycloidal rotors because of the order of magnitude difference in Reynolds numbers. Increasing the number of blades from two to four increased the aerodynamic efficiency for all pitching amplitudes ±25° and higher.
Bell V-280 Valor: A JMR-TD Program Update
Authors:   Bell Helicopter Textron, Ehinger Ryan , Gehler Chris , Allen Scott
Published: September 2024

Bell Helicopter's Team Valor concept for a next-generation tiltrotor is the V-280. Bell Helicopter is manufacturing the V-280 Air Vehicle Concept Demonstrator (AVCD) for the Joint Multi-Role Technology Demonstrator (JMR-TD) program under a Technology Investment Agreement (TIA) with the US Army. The V-280 AVCD is designed and built to provide revolutionary capability in vertical lift while meeting the affordability and mission performance needs of a Future Vertical Lift program of record. Key Performance Parameters (KPPs) for the V-280 include its 280 knot cruise speed, 6K 95°F high hot performance, exceptional low speed agility, and twice the range of comparable platforms it will replace. The V-280 is slated for first flight in 2017 and is currently in final assembly at Bell Helicopter's Amarillo test facility. The aircraft represents an ultra modern "design for manufacturing" approach that leverages cost advantages from recent Bell experience in commercial product development. The V-280 will revolutionize vertical lift capability for the armed services and bring affordability to the mission.
Using Redundant Effectors to Trim a Compound Helicopter with Damaged Main Rotor Controls
Authors:   Rensselaer Polytechnic Institute, Reddinger Jean-Paul , Gandhi Farhan
Published: September 2024

Control of a helicopter's main rotor is typically accomplished through use of three hydraulic actuators that act on the non-rotating swashplate and position it to achieve any combination of collective and cyclic blade pitch. Failure of one of these servos can happen through loss of hydraulic pressure or by impingement of the piston within the hydraulic cylinder. For a compound helicopter with an articulated main rotor, a range of failed servo states (by piston impingement) are simulated in RCAS at hover, 100 kts, and 200 kts, to show the extent to which the compound effectors can generate additional forces and moments to maintain trimmed flight. After the loss of control of any of the three main rotor actuators in hover, the compound helicopter is capable of trimming with little change to the state of the vehicle by replacing control of the locked servo with control of rotor speed. This strategy can be used to maintain trim over 6 - 12% of the total servo ranges. At forward flight speeds, each of the three actuators produces a different result on the trimmed aircraft due to the non-axisymmetry of the rotor. Reconfiguration is accomplished through use of the ailerons, stabilator pitch, wings, and wing-mounted propellers to trim rotor produced roll moments, pitch moments, lift, and drag, respectively. The additional effectors in forward flight increases the range of tolerable failures to 20 - 63% of the maximum actuation limits.
Recent advances in antileishmanial drugs: New leishmaniasis medicine through repurposing approach
Authors: Lye Lon-Fye , Lin Chin-Fu , Ou Yen-Chuan , Chen Chih-Ming
Published: September 2024

Leishmania is a parasitic protozoan belonging to the family Trypanosomatidae. Leishmaniasis, caused by infection with Leishmania parasites, can manifest in three primary forms: cutaneous, mucocutaneous, and visceral. Approximately 2 million individuals worldwide are affected by leishmaniasis, with an estimated 0.7–1 million new cases occurring annually and around 20,000–65,000 deaths reported annually. Current chemotherapy for leishmaniasis faces several challenges, including high costs, adverse effects, drug resistance, and disease relapse. Consequently, there is an urgent need for alternative treatments. Drug repurposing presents a promising strategy for discovering and developing new antileishmanial therapeutics. This review aims to explore and summarize recent advances in the identification of antileishmanial drugs, highlighting the successful repurposing of existing drugs for leishmaniasis and their transition from academic research to industrial application. These advancements are primarily based on integrated computational and experimental approaches, including in silico, in vitro, and in vivo screening, as well as biological and biochemical analyses to identify effective antileishmanial agents. Further studies are needed to elucidate the mechanisms of action of these new leads and to conduct preclinical and clinical evaluations of the identified drugs for potential antileishmanial therapy.
Comparison of preoperative and postoperative results of “canalicular triangular flap” and “triangular three-snip” punctoplasty techniques in patients with punctum stenosis using anterior segment optical coherence tomography
Authors: Turkoglu Elif H L , Comez Arzu T , Demir Mustafa
Published: September 2024

Purpose:

To compare the results and success rates of patients with epiphora due to punctal stenosis operated with the “canalicular triangular flap punctoplasty” and the “triangular three -snip punctoplasty” using anterior segment optical coherence tomography (AS-OCT).

Methods:

This study is a retrospective cohort analysis of patients who were diagnosed with punctal stenosis and underwent canalicular triangular flap or triangular three-snip punctoplasty between September 2021 and June 2022.

Results:

The study included 80 eyes of 43 patients consisting of 15 males and 28 females. Forty eyes underwent canalicular triangular flap punctoplasty (Group A) and 40 eyes underwent triangular three-snip punctoplasty (Group B) technique. The mean age of the patients was 63.9 ± 10.9 years (37–88 years). In Group A, the anatomic success was 100% and functional success was 95% at 6 months.In Group B, 77.5% functional success and 75% anatomic success were achieved at 6 months.

Conclusions:

The canalicular triangular flap technique was more successful in providing punctal patency both anatomically and functionally than the triangular three-snip punctoplasty. AS-OCT is a method that provides objective, quantitative results in the diagnosis and follow-up of punctal stenosis and may be used more widely in punctum and vertical canaliculi pathologies.
Reading eye movements among homonymous hemianopia
Authors: Gupta Nayan , Atiya Ayisha , Hussaindeen Jameel R , Ambika Selvakumar V
Published: September 2024

Purpose:

To measure the reading eye movement’s parameters and quantify the oculomotor dysfunction among subjects with homonymous hemianopia compared to age-matched controls using ReadAlyzer.

Methods:

This was a prospective study carried out in the neuro-optometry clinic of a tertiary eye care hospital in South India, from October 2018 to Janurary 2019. Fifty consecutive patients diagnosed with homonymous hemianopia were enrolled in the study after obtaining their written informed consent. Reading eye movements were measured using ReadAlyzer in patients with homonymous hemianopia and age-matched controls. Reading eye movement parameters were represented in median [interquartile range (IQR)].

Results:

Subjects with homonymous hemianopia showed increased number of fixations/100 words- median (IQR) [175 (80–270)] compared to controls [91 (52.5–127.5)]; increased number of regressions/100 words [33 (-13–79)] compared to controls [18 (-10–46)]; and reduced reading rate [93 (46–140) words/min] compared to controls [186 (144–228) words/min] (Mann–Whitney U test, P ≤ 0.05). Similar trend was observed for grade level equivalent 2 (0–4) and regression to fixation ratio 15 (1–29) compared to controls [grade equivalent 7 (3–11) and regression to fixation ratio 11 (-2–24)] (Mann–Whitney U test, P ≤ 0.005).

Conclusion:

Reading eye movements assessed using ReadAlyzer are found to be significantly impaired among homonymous hemianopias compared to age-matched controls (Mann–Whitney U test, P ≤ 0.05).
Corneal biomechanics in patients with allergic conjunctivitis
Authors: Wan Abdul Halim Wan Haslina , Jamaludin Mohd Ihsan , Cheng Teck Chee
Published: September 2024

Allergic conjunctivitis (AC) comprises a group of conditions triggered by environmental allergens, substantially diminishing the quality of life, particularly among children and adolescents. The mechanical impact of eye rubbing in patients with AC is known to induce biomechanical alterations in the cornea. Modern instruments enable the detection and quantification of these corneal biomechanical changes. The ocular response analyzer and CorVis ST have become standard tools for assessing corneal biomechanical properties. We conducted a review of studies that have investigated corneal biomechanics in patients with AC using both devices to elucidate the association between corneal biomechanical changes and early ectasia development. Our analysis highlights significant findings regarding the tomographic biomechanical index parameter in corneal biomechanics among patients with AC. These findings underscore the importance of ocular screening for all patients to promptly detect subclinical keratoconus changes, thereby improving disease management and outcomes.
How do young adults deal with suicidal ideation? A qualitative study of the experiences of stakeholders
Authors: Nair Vasundharaa S. , Joseph Miriyam , Ealias Neslin M. , Mohan Sharanya , Sreedaran Priya
Published: September 2024

Background:

Persistent suicidal ideation, self-harm behaviors, and suicide attempts constitute suicidality and are consistent predictors for future suicides. Research on what protects individuals from harming themselves is equivocal. While factors like impulsivity could increase risk of suicide, research is needed on what stops people from acting out on self-harm thoughts/suicidal ideation.

Aim:

To explore the help-seeking behaviors and other protective factors during periods of suicidality in individuals at risk of suicide.

Method:

This study aimed to explore help-seeking behavior and other protective factors that prevent or delay self-harm and suicide attempts during suicidality in individuals at risk. We used a qualitative study design and interviewed 15 participants comprising at-risk individuals, caregivers, and mental health professionals (MHPs). We used thematic analysis for deriving themes.

Results:

Themes in ‘at-risk individuals’ include mental state during suicidality, handling of oneself during suicidality, and seeking help from support systems. Themes from caregivers included handling of crises and the role of informal and formal support systems. Themes from MHPs included phenomenology of suicidality, handling of suicidality, help-seeking, and support systems.

Conclusion:

At-risk individuals handle suicidality by either managing themselves on their own or seeking help from informal sources and formal health systems. Caregivers appear to be crucial stakeholders in help-seeking during self-harm. The involvement of caregivers – in discussion with the at-risk individual – should be a necessary component of suicide risk management. Suicide prevention policies at institutional, regional, and national levels should include strategies to prevent burnout and other occupational health issues in MHPs.
A comparative study on hair cortisol concentration among generalized anxiety disorder patients with and without alcohol dependence syndrome presenting to a tertiary care center: A pilot study
Authors: Bijjal Somashekhar , Huchegowda Ravish , Gowda Srinivas H. , Harbishettar Vijaykumar , Deshpande Srinivas R. , Sharma Manoj K. , Raju G M
Published: September 2024

Background:

Generalized anxiety disorder (GAD) affects up to 6% of the population, which if not detected early and adequately treated will continue as a hidden impairment resulting in disability.

Aim:

The primary objective of the study is to assess the hair cortisol levels (HairF) in persons with GAD with and without alcohol dependence syndrome (ADS), and the secondary objective is to assess whether HairF can be used as a biomarker for assessment of GAD.

Materials and Methods:

This comparative study was done on 94 subjects (68 persons with GAD with or without ADS and 26 healthy controls) who were divided into three groups. Hamilton Anxiety Rating Scale (HAM-A) and Patient Health Questionnaire-4 (PHQ4) were also used to assess severity of anxiety symptoms. These scores were compared with HairF. Diagnostic accuracy of the HairF analysis test was done. Statistical analysis was done using SPSS version 20.

Results:

The study found higher levels of HairF in persons with GAD (mean 189.4 ± 33.1) and GAD with ADS (164.2 ± 47.6) compared to healthy controls (mean 45.34 ± 40.7), which were statistically significant. Correlation of HAM-A and PHQ4 scores and HairF also showed positive correlation. The receiver operating characteristic curve suggested the best cutoff point at 88.4 pg/mg with a sensitivity of 98.5% and a specificity of 92.5%, clearly differentiating GAD from healthy controls.

Conclusion:

HairF were found to be higher in patients with GAD irrespective of ADS as comorbidity. The study supports the possibility of the HairF as a possible biomarker to detect GAD and play a complementary role in a multidimensional approach for management of chronic stress and anxiety.
Focus group discussion with the medical interns regarding psychiatry posting
Authors: Deshpande Sharmishtha , Agawane Shubhangi , Zachariah Aaron , Innamuri Raviteja , Menon Vikas
Published: September 2024

Background:

Medical interns have 2 weeks compulsory internship in psychiatry.

Aim:

We tried to explore their learning and views about psychiatry during these 2 weeks. To document verbatim their account about the knowledge gained and their experiences during the psychiatry internship posting and derive prominent themes.

Methods:

Focus group discussion was conducted at the end of the posting using a semistructured questionnaire for seven consecutive batches of interns posted in psychiatry. To enhance trustworthiness, we utilized member checking, data triangulation, and peer debriefing. Their routine during posting, competencies, expectations from the posting, and frustrations were the main points discussed. The interns willingly participated and discussed their views about psychiatry posting.

Results:

They were aware of psychiatry as an important medical discipline and had a fair degree of knowledge about it. Most of them found the posting useful. The interns had not attained the required competencies in handling emergencies and use of psychiatric drugs.

Conclusion:

Involvement of senior faculty and formative assessments will be necessary in the training of medical interns. This can ensure that they gain the required competencies.
On nonlinear iterated function systems with overlaps
Authors: Solomyak Boris
Published: September 2024

We construct an example of an iterated function system on the line, consisting of linear fractional transformations, such that two of the maps share a fixed points, but the dimension of the attractor equals the conformal dimension, so that there is no “dimension drop”.
Modern Tools for Tribological Optimization of EV Transmissions and e-Axles
Authors: Zhmud Boris , Merelli Michele
Published: September 2024

EV motors and transmissions operate at high speeds and handle high power densities, placing heavy demands on bearings, seals, and gears.

TEHD and meshless CFD simulations open new ways to the design and optimization of lubrication and thermal management solutions for EV transmissions and e-axles. Properly parametrized CAE models can provide valuable insights into the effects of different lubricant properties on cooling and lubrication efficiencies, thereby helping in matching the lubricant and hardware characteristics for optimal performance.

In the present communication, we demonstrate the effects of different lubricants and surface finishing technologies on the tribology of high-speed gears using tribological tests and simulations. Important roles of lubricity additives and surface finish optimization are highlighted in conjunction with a move towards ultralow viscosity fluids.
Battery and Powertrain Sizing for L7e-CU Type Electric Vehicle
Authors: Rupnik Urban , Vukotić Mario , Manko Roman , Alić Alen , Čorović Selma , Miljavec Damijan
Published: September 2024

The aim of paper is to present the workflow of battery sizing for electric L7e-CU type vehicle. The intention is to use it as last-mile delivery multi-purpose vehicle. Based on legislation limits and pursuing the real-world driving cycle, major vehicle characteristics as total vehicle mass including payload and wheel size are determined. Vehicle total energy consumption is calculated knowing vehicle power in time. Accordingly, to selected gearbox ratio the electric motor nominal power-speed curve is defined as well as the nominal torque-speed curve. Applying vehicle acceleration dynamics involving limits considering resistive forces, acting on the vehicle, e.g. slope, friction, air drag, and total inertia, referred to the electric motor through the gearbox the electric motor over-load-ability characteristics are calculated. Next, the motor design is defined and optimized. Defining required vehicle range at given driving cycle and knowing the vehicle and all powertrain characteristics allows to properly define the battery characteristics e.g. nominal voltage, battery cell type, current capacity, energy storage, dimensions and its mass.
Efficient GPS Route Matching Method for Battery Electric Bus Fleets
Authors: Hitz Arne , Konzept Anja , Reick Benedikt , Rheinberger Klaus
Published: September 2024

A challenge of public transportation GPS data is the frequent utilization of monitoring systems with low sampling rates, primarily driven by the high costs associated with cellular data transmission of large datasets. Altitude data is often imprecise or not recorded at all in regions without large elevation changes. The low data quality limits the use of the data for further detailed investigations like a realistic energy consumption forecast for assessing the electrical grid load resulting from charging the vehicle fleet. Modern research often reconstructs speed data only, or uses additional GPS loggers, which is associated with increased costs in the vehicle fleet. The importance of precise and high-quality altitude data and specialized expertise in mountainous regions are frequently overlooked. This paper introduces an efficient new route matching method to reconstruct speed and respective road slope data of a GPS signal sampled at low frequency for a public transportation electric bus. To that end, an algorithm is presented which merges speed data with the corresponding altitude information. It accomplishes this by optimizing time segments of the resampled speed signal based on the distance traveled on the road, which is extracted via map matching. The optimized data feeds a verified longitudinal dynamics model of a battery electric bus and evaluates the energy consumption and battery SOC for different operating conditions. The consumption is compared to the energy consumption evaluated by a simulation model using high-frequency sampled real route data collected by a dedicated GPS data logger installed in a battery electric bus to verify the algorithm. The proposed method reconstructs and approximates the driven route (speed and slope) with high resolution. Therefore, it enables model-based predictions for the bus fleet for different operating conditions e.g. ambient temperature, battery age or loading. The method facilitates the optimization of fleet operations, focusing on battery sizing, charging management and energy grid conservation. In subsequent works, the toolchain is integrated into an ecosystem supporting bus and energy grid operators.
Risk Analysis for Electric Vehicle Investments: Beta Trends and Monte Carlo Insights
Authors: Gutierrez Marcos , Taco Diana
Published: September 2024

The electric vehicle (EV) industry is seeing a significant increase in global investments. However, it faces major challenges, especially the shortage and rising costs of key raw materials needed for battery production. This situation creates higher economic risks for investors.

This paper evaluates the risks of investing in the EV industry, considering current supply chain issues related to finding raw materials, manufacturing, and selling. The evaluation uses the beta coefficient, which measures how much an individual stock’s price is expected to fluctuate compared to the overall stock market. To examine the beta coefficient’s variability, a Monte Carlo simulation is used to calculate its changes, providing insights into the volatility of assets in the EV industry relative to market conditions. The simulation is repeated multiple times until consistent results are obtained. The main goal of this study is to offer a forward-looking tool to help with investment decisions in the production of electric vehicles. This method goes beyond traditional profitability measures by including considerations of uncertainty, risk factors, and variables. These factors, though inherently uncertain and unable to be assigned specific values, are defined within a range of probabilities. The simulation results, expressed in terms of probability, show that the beta coefficient for the EV automotive sector is riskier than the reference value. By providing a detailed perspective on risk assessment, this study aims to help investors make informed and well-grounded decisions, enhancing their understanding of the challenges and opportunities in the evolving EV investment landscape.
Dual Injection Concept and Lean Burn Characteristics with Methanol on a SI-Engine
Authors: Fitz Patrick , Fellner Felix , Rößlhuemer Raphael , Härtl Martin , Jaensch Malte
Published: September 2024

The research for sustainable alternative fuels for combustion engines was driven by the urgency to meet future emission regulation norms and mitigate climate change and dependency on fossil fuels. In this context, methanol emerges as a promising candidate due to its potential for greenhouse gas-neutral production methods and its advantageous characteristics for employment in SI engines. Adverse effects, such as elevated emissions due to incomplete combustion along with liner impingement and oil dilution as a consequence of the high injected fuel mass and the large enthalpy of vaporization, can be improved by a dual injection concept.

The tests were conducted on a single-cylinder research engine derived from a common passenger vehicle engine. The exhaust gas composition was measured with an FTIR-analyzer employing a methanol-specific evaluation method, standard exhaust gas analyzers, and a solid particle counter system with 10 and 23 μm cut-off sizes. The ratio of DI mass to total mass injected in one cycle (xDI) was varied at low-, mid-, and high-load operation points at 2000 rpm and stoichiometric conditions. Further investigations for lean-burn concepts with a variation of xDI were carried out and evaluated based on variables such as engine performance, efficiency, and emissions.

The measurements show a strong charge cooling effect for DI, thereby reducing NOx, although this effect saturates at a mid-load. By splitting the injected fuel mass, an xDI of 30 % shows the highest reduction in NOx at high-load and a reduction of unburned fuel in the exhaust gas of up to 62 %. Particle measurements indicate the interaction of methanol with the liner for both PFI and DI, leading to increased particle emissions. For high-load and dual injection with xDI = 30 % and 50 %, these emissions are found on a level one magnitude lower than compared to DI operation. Lean burn operation with dual injection shows the extension of the lean burn limit at certain points. However, the potential efficiency increase is diminished by undesirable combustion characteristics with prolonged burn durations.
Modeling and Experimental Validation of a Pure Methanol-Fueled Small SI Engine: Impact of the Laminar Flame Speed Correlation
Authors: Frasci Emmanuele , Sementa Paolo , Arsie Ivan , Vaglieco Bianca Maria
Published: September 2024

In a context of growing concern for vehicle-related CO2 and pollutant emissions, non-conventional fuels like methanol (CH3OH) represent a valid alternative to fossil fuels to decarbonize the transport sector in a reasonable time. This is mainly due to its lower carbon content than conventional gasoline and diesel. Moreover, methanol can be obtained either from biomass or CO2 capture from the atmosphere, which makes the latter a renewable fuel. Given the possibility of being stored in liquid phase at standard temperature and pressure (STP), methanol is very suitable for Light Duty Vehicles (LDVs), in which the need to contain fuel tank dimensions is relevant. Regarding the deployment of methanol as a fuel, it is not very challenging, as it can be adopted in current production Internal Combustion Engines (ICEs) either in pure form or in blend with other fuels without any significant modifications.

Within this context, the present work aims to assess, in both experimental and simulation environments, the benefits of pure methanol fueling of Spark Ignition (SI) engines. Particularly, a small single-cylinder production SI engine has been tested on the engine test bench at different speeds and air-fuel ratios, at unthrottled conditions. Besides the test campaign, a 1-D model of the engine under study has been developed, with a particular focus on the simulation of methanol combustion. Particularly, different correlations for the laminar flame speed, implemented in the combustion model, have been investigated to evaluate their effect on the prediction of performance, efficiency, and pollutant emissions. Combustion, heat transfer, and pollutant emissions sub-models have been tuned and validated based on the experimental data. Both experimental measurements and simulation results evidence that methanol fueling allows for improving engine efficiency, while reducing regulated pollutant emissions from a current production SI engine, if compared to conventional gasoline, especially under lean-burn operating conditions. This work is useful for future activities, which will concern the optimization of the Ignition Timing (IT), as well as the investigation of the knock tendency of methanol-fueled SI engines.
Novel Chemical Kinetics Mechanism for Robust Simulation of Multi-Component Fuel Blends in Engine Conditions
Authors: Salahi Mohammad Mahdi , Mahmoudzadeh Andwari Amin , Kakoee Alireza , Hyvonen Jari , Gharehghani Ayat , Mikulski Maciej , Lendormy Éric
Published: September 2024

Ammonia, with its significant hydrogen content, offers a practical alternative to pure hydrogen in marine applications and is easier to store due to its higher volumetric energy density. While Ammonia's resistance to auto-ignition makes it suitable for high-compression ratio engines using pre-mixed charge, its low flame speed poses challenges. Innovative combustion strategies, such as dual-fuel and reactivity-controlled compression ignition (RCCI), leverage secondary high-reactivity fuels like diesel to enhance Ammonia combustion. To address the challenges posed by Ammonia's low flame speed, blending with hydrogen or natural gas (NG) in the low reactivity portion of the fuel mixture is an effective approach. For combustion simulation in engines, it is crucial to develop a chemical kinetics mechanism that accommodates all participating fuels: diesel, Ammonia, hydrogen, and NG. This study aims to propose a kinetics mechanism applicable for the combustion of these fuels together. The mechanism is tailored for engine conditions, including high pressures and temperatures, and diverse chemical species concentrations. To render the mechanism suitable for computationally efficient 3-D Computational Fluid Dynamics (CFD) simulations, it is reduced and contains 82 species and 636 reactions, with N-heptane serving as the surrogate for diesel fuel. The mechanism is tuned using optimization methods to match available experimental data on ignition delay time (IDT) for N-heptane. The prediction of IDT and laminar burning velocity values by the mechanism is validated with available experimental data. Additionally, 3-D CFD and quasi-dimensional multi-zone engine simulations are conducted using the new mechanism to verify engine operating parameters against available experimental data.
Performance Analysis of Hydrogen Combustion under Ultra Lean Conditions in a Spark Ignition Research Engine Using a Barrier Discharge Igniter
Authors: Avana Massimiliano , Ricci Federico , Papi Stefano , Zembi Jacopo , Battistoni Michele , Grimaldi Carlo N.
Published: September 2024

The global push to minimize carbon emissions and the imposition of more rigorous regulations on emissions are driving an increased exploration of cleaner powertrains for transportation. Hydrogen fuel applications in internal combustion engines are gaining prominence due to their zero carbon emissions and favorable combustion characteristics, particularly in terms of thermal efficiency. However, conventional Spark-Ignition (SI) engines are facing challenges in meeting performance expectations while complying with strict pollutant-emission regulations. These challenges arise from the engine's difficulty in handling advanced combustion strategies, such as lean mixtures, attributed to factors like low ignition energy and abnormal combustion events.

To address these issues, the Barrier Discharge Igniter (BDI) stands out for its capability to generate non-equilibrium Low-Temperature Plasma (LTP), a strong promoter of ignition through kinetic, thermal, and transport effects. Its surface discharge also facilitates combustion promotion across a wide area, overcoming the limitations of conventional spark systems. The research outlined in this study involves conducting experiments that integrate hydrogen (H2) with LTP discharge. Tests were carried out using a single-cylinder research engine by varying the air-fuel mixture and maintaining the same load condition and the same engine speed. Results from the application of BDI, revealed an acceleration in the evolution of the flame front when compared to conventional spark methods. This effect extended the lean stable limit of the engine, leading to reduction in the fuel consumption and emissions and improvements in the delivered power close to the engine lean stable limit. Additionally, adjustment of BDI control parameters played a crucial role in enhancing igniter performance, contributing significantly to a more comprehensive understanding of the innovative approach presented in this study.
Techno-Economic Analysis of Mobile Carbon Capture for Heavy Duty Applications
Authors: SAAFI Mohamed Ali , Hamad Esam
Published: September 2024

Since signing the legally binding Paris agreement, fighting climate change has been an increasingly important task worldwide. One of the key energy sectors to emit greenhouse gases is transportation. Therefore, long term strategies all over the world have been set up to reduce on-road combustion emissions. One of the emerging alternative technologies to decarbonize the transportation sector is Mobile Carbon Capture (MCC). MCC refers to the on-board separation of CO2 from vehicle exhaust. To accurately assess this technology, a techno-economic analysis is essential to compare MCC abatement cost to alternative decarbonization technologies such as electric trucks. Adding to the system capital and operational costs, our study includes mass penalty costs, CO2 offloading and transport costs for different transport scenarios. To better relate to a single consumer (driver), the cost can be converted from euro per-tCO2 to euro per-trip or euro per-mile. A sensitivity analysis is then conducted to quantify the impacts of the most sensitive parameters on the overall abatement costs. This study shows that MCC should be explored as a viable climate mitigation option. The novelty of this work comes from the detailed cost categories taken into consideration in the analysis, for a better MCC technology feasibility and impact analysis study. The results show that MCC represents an economically promising solution to decarbonize the heavy-duty sector, through its decreased TCO and MAC values compared to BEVs and FCEVs.
Nickel Alloy, Corrosion and Heat-Resistant, Sheet, Strip, and Plate 41.5Ni - 16Cr - 37Fe - 2.9Cb (NB) - 1.8Ti Consumable Electrode or Vacuum Induction Melted, 1750 °F (954 °C) Solution Heat Treated
Authors:   AMS F Corrosion and Heat Resistant Alloys Committee
Published: September 2024

This specification covers a corrosion- and heat-resistant nickel alloy in the form of sheet, strip, and plate 1.000 inch (25.40 mm) and under in nominal thickness.
Process Failure Mode and Effects Analysis (PFMEA) and Control Plans
Authors:   G-22 Aerospace Engine Supplier Quality (AESQ) Committee
Published: September 2024

This standard defines requirements for the identification, assessment, mitigation, and prevention of risk in the manufacturing process through the application of Process Flow Diagrams (PFDs), Process Failure Mode and Effects Analysis (PFMEA) and Control Plans throughout the life cycle of a product.

This standard aligns and collaborates with the requirements of AS9100, AS9102, AS9103, and AS9145.

The requirements specified in this standard apply in conjunction with and are not alternative to contractual and applicable statutory and regulatory requirements. In case of conflict between the requirements of this standard and applicable statutory or regulatory requirements, the latter shall take precedence.
When Grief Arrives: An oral history of grief and death within queer, trans and Black, Indigenous and people of colour communities
Authors: Ah-fat Anne-lise
Published: September 2024

When Grief Arrives is a narrative therapy and oral history project aimed at re-storying narratives of grief and loss within queer, trans and Black, Indigenous and people of colour communities. The project documents multi-storied accounts of grief that resist the individualisation and isolation of grieving that is common under settler colonialism and capitalism. By honouring overlooked landscapes of experience, the project seeks to generate solidarity and interconnection through shared knowledges. This article discusses the project’s methodology, ethical considerations, and the transformative potential of collective storytelling in fostering solidarity and healing within marginalised communities.
Delusions: Seeking epistemic justice for the most unusual of stories
Authors: Kennedy Hamilton
Published: September 2024

The label of delusion can be so powerful that people so labelled are no longer believed or supported in preferred ways by those around them. This leads to a lack of meaningful and non-pathologising support for their significant, and at times unusual, beliefs. This phenomenon constitutes a form of epistemic injustice. To address this issue, this paper outlines specific approaches practitioners can adopt to better respond to such beliefs, illustrating these strategies with real-world examples from practice. By doing so, it aims to foster a form of epistemic justice that respects the knowledge and experience of people labelled as delusional and supports them to understand and lessen the impact of these often-distressing experiences. This paper is informed by research undertaken with people who had been labelled by psychiatry as “delusional”.