bluuebunny/crossref_metadata_2025 huggingface dataset:
Investigation of Engine-Airframe Vibration Due to Main Rotor Hub Loads Using a Substructuring Framework
Authors:   University of Maryland, Sidle Stacy ,   Sikorsky Aircraft, Feshler Matt ,   GE Aviation, Kull Peter , Sridharan Ananth , Chopra Inderjit
Published: September 2024

This paper presents a methodology to analyze the coupled structural dynamic response of an elastic airframe and engines of a helicopter in response to main rotor and tail rotor hub loads. Transfer functions of individual components (airframe, engine, mount struts and torque tube) are coupled together using a sub-structuring approach to obtain consistent coupled solutions of the entire system. Using this approach, the two-engined and four-bladed S- 92 R helicopter is analyzed using NASTRAN-based models of the Sikorsky airframe and GE CT7-8 R engine. This ultra-efficient substructuring approach is validated against the fully coupled NASTRAN model using forced response studies. Characteristics of the mount properties, i.e., the torque tube stiffness, and aft mount stiffness and damping are systematically varied to study their effect on the engine vibration response. The fore and aft mount element properties for minimizing the 8/rev engine response are identified without increasing 4/rev response. A compromise between 4/rev and 8/rev response is also identified from parametric studies of rear mount properties, using just 3 parameters to represent the design space. Using the sub-structuring approach presented here, future studies can be performed to rapidly match airframe characteristics with available engines at approximately 1000 times the speed of running a detailed finite element model (millions of degrees of freedom), without any reduction in accuracy.
Dynamic Wake Inflow Modeling in Ground Effect for Flight Dynamics Applications
Authors:   Roma Tre University, Gennaretti Massimo ,   University of Maryland, Celi Roberto , Pasquali Claudio , Cardito Felice , Serafini Jacopo , Bernardini Giovanni
Published: September 2024

Rotor dynamic wake inflow modeling is one of the main issues in the development of efficient and reliable tools for design and flight dynamic simulation of rotorcraft. In general, it is affected by the operating condition (hovering, advancing, steady or maneuvering flight), but the interference with external obstacles might play a crucial role, especially during landing or close-to-ground procedures. The aim of this paper is the presentation of a LTI, finite-state model for the prediction of dynamic wake inflow of helicopter rotors in ground effect. First, two high-fidelity boundary-element aerodynamic formulations capable of taking into account ground effects on wake dynamics are applied, compared and correlated with experimental data. Then, finite-state dynamic inflow models are extracted from a set of responses to kinematic perturbations provided by the high-fidelity aerodynamic tool. The capability of the proposed low-order modeling to capture with good accuracy the time evolution of dynamic wake inflow induced by arbitrary rotor commands perturbations is tested by comparison with the predictions directly provided by the time-marching high-fidelity solver.
Towards Handling Qualities Requirements for High-Speed Compound Rotorcraft
Authors:   The Pennsylvania State University, Horn Joseph , Thorsen Adam , Conti Angelina
Published: September 2024

Handling qualities requirements for future high-speed rotorcraft are investigated. Two Mission Task Elements (MTEs) are developed and tested in piloted simulations of a notional winged compound rotorcraft with a full authority Non-linear Dynamic Inversion (NLDI) controller. The combat break turn maneuver was modified from a previously developed break turn MTE, and a formula for time-to-complete was derived to separate rotorcraft performance properties from the handling qualities. A decelerating approach MTE was modified from the current MTE in ADS-33F to use a Precision Approach Path Indicator (PAPI) cue. Piloted simulations were performed with variations in the roll and pitch axis command filters. Results showed that the break turn is suitable for identifying handling qualities deficiencies in the roll axis. The performance criteria for the proposed decelerating approach MTE need to be tightened to better identify handling qualities deficiencies in the pitch axis.
Development and Evaluation of New High-Speed ADS-33 Mission Task Elements using a Tiltrotor Platform
Authors:   The Boeing Company, Brewer Roy , Conway Frank , Mulato Ray
Published: September 2024

The Boeing Company has developed and evaluated several new High Speed Mission Task Elements (MTEs) as part of the National Rotorcraft Technology Center (NRTC) program "Handling Qualities Requirements for Future Configurations and Missions". One of the main goals of this program, which is a collaboration between industry, academia and the U.S. Government, is to update the current Aeronautical Design Standard Performance Specification ADS-33E-PRF to provide the new MTEs that would be required to support Future Vertical Lift (FVL) requirements. Boeing's contribution to the program includes the following MTEs: High Speed Acceleration / Deceleration, High Speed Steep Descent, and High Speed Break Turn. These MTEs were primarily evaluated with Boeing and Army pilots using a high-fidelity simulation of a tiltrotor configuration based on the production MV-22B. The maneuvers evaluated were found to be effective at determining handing qualities in these regimes, at least for the tiltrotor configuration.
Experimental and Numerical Investigation of Lubricant Retention on a Rotating Disc and Gear Teeth
Authors:   United Technologies, Acharya Ranadip ,   US Army ADD/AATD ARDEC, Maglieri John , Zhang Huan , Chaudhry Zaffir , Thompson Bruce
Published: September 2024

Loss of the primary lubrication in a helicopter gearbox can result in a very rapid or even immediate failure of the system due to the much-reduced heat removal and the degrading tribological performance of the highly loaded gear contacts. While a limited understanding of this topic may be an acceptable risk for ground vehicles, however, a properly functioning gearbox is flight safety critical for helicopters. Therefore a deeper understanding of the degradation mechanisms is essential to accurately assess the time duration in which the helicopter gearbox can function under oil-out conditions and evaluate designs targeting the desired extension. Current methods for predicting the gearbox life and performance under the loss-of-lubrication situation are indeed largely experimental and experience-based and they provide only limited insights into the underlying physics of the evolving tribology of gears and bearings. One of the major technical barriers that currently limit the physics-based predictive capability is a lack of reliable, quantitative modeling of lubricant retention on the gear tooth surface after the loss of lubrication. This paper first describes the film thickness measurement with the white light interferometry for the lubricant remaining on a glass disc after a certain number of revolutions at a given speed. This is followed by a description of a 3D numerical ANSYS CFX® model which mimics the experimental set-up. The controlling model parameters are the centrifugal and viscous forces, surface tension, temperature, and lubricant-disc contact angle. The predicted effects of rotation speed and temperature are validated by the experimental results. Finally, the modeling methodology is used to simulate the lubricant retention on a gear tooth surface over the range of temperature and speed of a typical helicopter gearbox.
Flight Evaluation of a Flexible Fabric Stabilizer for Sling Loads
Authors:   Natick Research Development Engineering Center, Tardiff Marc ,   US Army ADD, Cicolani Luigi , Nyren Daniel
Published: September 2024

Helicopter Sling Load is the most accurate form of aerial delivery in the military due to the ability to air land materiel in an exact location; however, some missions have a tendency for the payloads to become unstable due to both pilot-in-the-loop and aerodynamic effects. Past research demonstrated that allowing the container to rotate freely in yaw stabilizes pendulum motions. Other research utilized rigid fins affixed to the rear of the container. These methods work during tests; however, they become difficult to use in an operational environment. This paper discusses tests using a flexible fabric stabilizer that can be temporarily added to any payload. The flight tests were conducted Moffett Field, CA using the same payload as the previously mentioned research. Tests showed the flexible stabilizer provided an intermediate level of performance eliminating sling wind up and stabilizing pendulum motions out to the aircrafts’ power limit in exchange for very little operational overhead.
Demand Forecasting: Cross-Functional, Cross-Disciplinary Analytics
Authors:   Sikorsky a Lockheed Martin Company, Liu Ping
Published: September 2024

Accurate material demand forecasting can lead to significant cost savings, greater competitiveness and improved customer satisfaction. However, more often than not, demand forecasting as a business function is carried out poorly, with forecast accuracy often not significantly better than the naïve forecast. To appropriately address these concerns and satisfy overall business objectives, it's increasingly important to have a holistic strategy to improve demand forecast accuracy through a well thought-out enterprise data strategy, applications of advanced forecasting methods as well as synchronized cross functional business processes. This paper describes data types that are essential to demand forecasting, investigates advanced analytics methods such as ARIMA and survival analysis and discusses the application of these methods for the purpose of fleet sustainment demand forecasting. Lastly, this paper addresses the business process needed to continuously monitor and improve forecast performance.
Implementing B-BBEE: Leader Experiences in the South African Banking Industry
Authors: Myeni Thembekile P. , Singh Paul
Published: September 2024

Orientation: Large banking institutions in South Africa remain complex organisations facing a myriad of challenges as they navigate the Fifth Industrial Revolution (5IR) and strive to remain relevant. A significant challenge relates to how these organisations can utilise Broad-Based Black Economic Empowerment (B-BBEE) to create diverse and inclusive teams for organisational success and sustainability.Research purpose: To explore the experiences and sense-making processes of senior leaders tasked with the implementation of affirmative action as part of a B-BBEE strategy as they navigate this responsibility within a South African bank.Motivation for the study: To shine on the complex experiences of senior leaders tasked with implementing affirmative action within a B-BBEE strategy in a large financial institution.Research approach/design and method: A qualitative interpretivist case study was applied to explore senior leaders’ negotiation of their perceptions and experiences of leading the implementation of B-BBEE in a large bank. Ten semi-structured interviews were utilised as the main data generation tool.Main findings: Study reveals how senior leaders hold strong convictions about the value of diversity and inclusion in the workplace. This included the continued necessity for legislation such as B-BBEE given South Africa’s racial history and existing personal biases that impact workplace diversity and inclusion. The study further reveals that senior leaders believe that B-BBEE is poorly implemented and attribute this to the tension leaders experience between diversity and performance, a lack of organisational policies and practices required to hold leaders accountable for B-BBEE implementation and leaders who lack the skills and expertise required to successfully create diverse and inclusive work environments.Practical/managerial implications: Positive contributions to diversity and inclusion policies and practices, leadership development and transformation of the banking organisations in South Africa and the industry at large.Contribution/value-add: Banking institutions as large market players can play a significant role in leading workplace transformation through improved implementation of diversity and inclusion legislation and principles within B-BBEE.
Neoliberalism in South African higher education language policy: A decolonial perspective
Authors: Munyaradzi Julliet
Published: September 2024

The global spread and hegemony of English as a medium of teaching, learning and research has come to be closely associated with neoliberalisation of higher education in the universities across the world, and has negatively impacted on epistemic issues, especially in Global South universities. No permanent solution has been found on challenges of English hegemony, particularly in African higher education. This article adds to the advancement of neoliberal discourse in higher education in South Africa by analysing neoliberal manifestations in its higher education language policy agenda. The article used desktop analysis to assess relevant literature on mainstream neoliberal ideologies and manifestations in the language policy reform post-apartheid. Drawing on relevant literature and through critical discourse analysis, it integrated evidence from the selected sources associated with mainstream neoliberal ideologies and then analysed the neoliberal manifestations in the language policy reforms pursued in South African post-apartheid context to bring out how the neoliberal actors in the higher education sector have reconfigured neoliberal principles. The decolonial perspective premised on concepts such as coloniality of being, power and knowledge was used to critique the neoliberal manifestations in South African higher education language policy directives. The paper presents the argument that universities in the country are deeply entrenched in linguistic hierarchisation which perpetuates epistemic injustices in teaching and learning. The African higher education should endeavour to underpin its language policies in indigenous knowledge systems to help harness the African content while existing in a global space where all knowledges should be regarded as equally relevant.Contribution: This article contributes to the emerging discourse of neoliberalism in higher education in the Global South and its impact on language policy formulation and implementation.
Tear film parameters and meibography in eyes of children with vernal keratoconjunctivitis
Authors: Gupta Ruchi , Arora Ritu , Gupta Isha , Jain Parul
Published: September 2024

Purpose:

To study tear film parameters and Meibomian glands in pediatric patients with vernal keratoconjunctivitis (VKC).

Methods:

Forty-four eyes of 22 patients with VKC and 44 eyes of 22 age-matched controls were studied in a hospital-based cross-sectional study. Each subject underwent a complete ophthalmological examination including slit-lamp biomicroscopy, non-invasive break-up time (NIBUT), fluorescein break-up time (FBUT), corneal fluorescein staining, and Schirmer’s test. Non-contact meibography was performed using a Sirius topographer.

Results:

All patients had VKC grades between 1 and 3 (Bonini scale). The mean NIBUT for cases was 8.83 ± 4.02 s and in controls, it was 15 ± 2.8 s (P value < 0.001). The mean FBUT for cases was 9.41 ± 3.45 s and in controls, it was 16.7 ± 2.5 s (P value < 0.001). Schirmer’s values were 32 ± 3.1 mm in cases and 21.4 ± 4.1 mm in controls, which were significantly higher (P value < 0.001). Also, 22.72% of the cases had corneal fluorescein staining in the form of superficial punctuate keratitis, whereas none of the control groups showed corneal staining. The examination of Meibomian glands using non-contact meibography showed a mean Meibomian gland dropout in the upper lid to be 29.7 ± 14.4% in VKC cases and 10.5 ± 3.2% in controls (P value < 0.001). Meibography of the lower lid showed 25.9 ± 10.2% dropout in cases and 20.5 ± 6.1% in controls (P value = 0.004).

Conclusion:

Tear film parameters were significantly deranged in children with VKC in the active stage as compared to age-matched controls. Children with VKC also had a higher Meibomian gland dropout.
Clinico-demographic profile and visual outcomes of pseudophakic bullous keratopathy in a multi-tier eyecare network in India
Authors: Das Anthony Vipin , Kaup Soujanya , Das Sujata
Published: September 2024

Purpose:

The purpose of this study is to present the clinico-demographic characteristics of pseudophakic bullous keratopathy (PBK), its visual outcomes, factors associated with the choice of treatment, and poor visual outcomes of PBK.

Methods:

In this hospital-based retrospective study, electronic medical records data of new patients who presented to a multi-tier ophthalmology hospital network in India (November 2010–June 2022) were extracted. Patients with at least 4 weeks of follow-up were analyzed for visual outcome data. Bivariate analysis and multivariate logistic regression were used to determine the factors associated with the treatment choice and poor visual outcomes.

Results:

Of the 3,323,247 electronic records (with an average follow-up of 293 days) examined, 10,522 eyes of 10,158 patients (0.3%) had PBK. The majority were managed non-surgically (n = 7372; 70.1%), with increased odds of poor visual outcome by 3.46 times (AdjOR: 3.04–3.92, P < 0.001). Those belonging to the non-paying category had higher odds of poor visual outcome (AdjOR: 1.48, 95%CI: 1.29–1.69; P < 0.001). Surgical management improved vision by 0.72 logMAR (95%CI: 0.60–0.73; P < 0.001). A total of 41.2% (n = 113/274) of cases that underwent Descemet’s membrane endothelial keratoplasty and 18.4% (n = 285/1551) of Descemet’s stripping endothelial keratoplasty attained last follow-up visual acuity (LVA) of 6/18 or better.

Conclusion:

About three in every thousand patients had PBK. Surgical interventions improved visual acuity significantly. About four in ten patients who underwent DMEK attained a vision of 6/18 or better at the last follow-up visit. Markers of lower socioeconomic strata were independently associated with poor visual outcomes.
Modified hepatic left lateral lobe inversion in laparoscopic proximal gastrectomy: An analysis of 13 cases
Authors: Lin Jian-An , Wu Chu-Ying , Ye Kai
Published: September 2024

BACKGROUND

In laparoscopic proximal gastrectomy (LPG), the prolapse of the hepatic left lateral lobe near the lesser curvature and esophageal hiatus can obstruct the field of vision and operation. Therefore, it is necessary to retract or obstruct the hepatic left lateral lobe to ensure a clear field of vision.

AIM

To investigate the safety and clinical efficacy of the modified hepatic left lateral lobe inversion technique for LPG.

METHODS

A retrospective analysis was conducted on the clinical data of 13 consecutive patients with early-stage upper gastric adenocarcinoma or adenocarcinoma of the esophagogastric junction treated with LPG from January to December 2023 at the Department of Gastrointestinal Surgery, Second Affiliated Hospital of Fujian Medical University. The modified hepatic left lateral lobe inversion technique was used to expose the surgical field in all patients, and short-term outcomes were observed.

RESULTS

In all 13 patients, the modified hepatic left lateral lobe inversion technique was successful during surgery without the need for re-retraction or alteration of the liver traction method. There were no instances of esophageal hiatus occlusion, eliminating the need for forceps to assist in exposure. There was no occurrence of intraoperative hepatic hemorrhage, hepatic vein injury, or hepatic congestion. No postoperative digestive complications of Clavien-Dindo grade ≥ II occurred within 30 days after surgery, except for a single case of pulmonary infection. Some patients experienced increases in alanine aminotransferase and aspartate aminotransferase levels on the first day after surgery, which significantly decreased by the third day and returned to normal by the seventh day after surgery.

CONCLUSION

The modified hepatic left lateral lobe inversion technique has demonstrated satisfactory results, offering advantages in terms of facilitating surgical procedures, reducing surgical trauma, and protecting the liver.
Evaluation and analysis of neurocognitive dysfunction in patients with colorectal cancer after radical resection: A retrospective study
Authors: Wang Yu , Wang Chao , Guo Han , Wang Su-Hang , Chen Fang-Fang , Chen Qiao-Xiang , Zhou Kai
Published: September 2024

BACKGROUND

With the continuous progress of colorectal cancer treatment technology, the survival rate of patients has improved significantly, but the problem of postoperative neurocognitive dysfunction has gradually attracted attention.

AIM

To analyze the risk factors for delayed postoperative neurocognitive recovery (DNR) after laparoscopic colorectal cancer surgery and constructed a risk prediction model to provide an evidence-based reference for the prevention and treatment of DNR after laparoscopic colorectal cancer surgery.

METHODS

The clinical data of 227 patients with colorectal cancer who underwent laparoscopic surgery and regional cerebral saturation oxygenation (rScO2) monitoring at our hospital from March 2020 to July 2022 were retrospectively analyzed. Common factors and potential factors affecting postoperative DNR were used as analysis variables, and univariate analysis and multifactor analysis were carried out step by step to determine the predictors of the model and construct a risk prediction model. The predictive performance of the model was assessed by the receiver operating characteristic (ROC) curve, the calibration curve was used to assess the fit of the model to the data, and a nomogram was drawn. In addition, 30 patients who met the inclusion and exclusion criteria from January 2023 to July 2023 were selected for external verification of the prediction model.

RESULTS

The incidence of postoperative DNR in the modeling group was 15.4% (35/227). Multivariate analysis revealed that age, years of education, diabetes status, and the lowest rScO2 value were the independent influencing factors of postoperative DNR (all P < 0.05). Accordingly, a DNR risk prediction model was constructed after laparoscopic colorectal cancer surgery. The area under the ROC curve of the model was 0.757 (95%CI: 0.676-0.839, P < 0.001), and the Hosmer-Lemeshow test of the calibration curve suggested that the model was well fitted (P = 0.516). The C-index for external validation of the row was 0.617.

CONCLUSION

The DNR risk prediction model associated with rScO2 monitoring can be used for individualized assessment of patients undergoing laparoscopic colorectal cancer surgery and provides a clinical basis for the prevention of DNR after surgery.
Benefits of endoscopic gallbladder stenting following percutaneous transhepatic gallbladder drainage
Authors: Niiya Fumitaka , Tamai Naoki , Yamawaki Masataka , Noda Jun , Azami Tetsushi , Takano Yuichi , Nishimoto Fumiya , Nagahama Masatsugu
Published: September 2024

BACKGROUND

Endoscopic transpapillary gallbladder drainage is challenging because of the complexity of the procedure and high incidence of adverse events (AEs). To overcome these problems, endoscopic gallbladder stenting (EGBS) after percutaneous transhepatic gallbladder drainage (PTGBD) can be effective, as it mitigates inflammation and adhesion.

AIM

To examine the benefits of EGBS after PTGBD to assess its efficacy and impact on AEs.

METHODS

We retrospectively analyzed data from 35 patients who underwent EGBS after PTGBD at a single center between January 2016 and December 2023. The primary outcomes were technical success and AEs, and the rate of recurrent cholecystitis was evaluated. In addition, the reasons for the failure of the procedure were identified.

RESULTS

Among the 35 patients, the technical success rate was 77.1% and the final contrast of the cystic duct was successful in 97.1% of patients. The incidence of early AEs was relatively low (11.4%), with no instances of cystic duct perforation. The rate of recurrent cholecystitis was 3.7%, and no other biliary events were observed.

CONCLUSION

EGBS after PTGBD may be significantly beneficial, with a substantial success rate and minimal AEs in both short- and long-term follow-ups.
Electrifying Vocational Trucks: An Overview of Advancements and Challenges in Electric and Hybrid Powertrains with Emphasis on Auxiliary Power Considerations
Authors: Beltrami Daniele , Villani Manfredi , Iora Paolo , Rizzoni Giorgio , Uberti Stefano
Published: September 2024

Electric and hybrid powertrains are steadily gaining popularity, showcasing their efficacy in reducing greenhouse gas emissions and pollution, particularly in urban environments. This also applies to medium and heavy-duty vocational trucks. Truck manufacturers have been expanding their electrified portfolio and some of them have already announced their plans to phase out fossil fuels. Vocational trucks are essential for the industry of commercial vehicles, represent an extremely heterogeneous class, and are often upfitted by third-party companies. In general, vocational trucks are designed for specific jobs. Typically, they are driven on short routes, but they may work for longer hours in comparison to freight transportation vehicles. Most importantly, among the broad category of vocational trucks, some vehicles greatly exploit power take-offs to drive auxiliary systems, like refuse trucks, utility trucks, cement trucks, and sweeper trucks. The benefits resulting from the kinetic energy regeneration of urban driving are undeniable and well-documented in several studies. Electrified short-haul, delivery, and box vocational trucks are indeed becoming widely accepted, but the auxiliaries of these trucks do not need a significant amount of energy. In this regard, few studies analyze the effect of auxiliary loads, even if they may require significant power and cause considerable drifts in energy consumption estimation. Indeed, velocity-based driving cycles are commonly used to assess the energy savings of electrified powertrains, but they only focus on analyzing the power needed for traction purposes. By focusing on vocational trucks that greatly rely on power take-offs and auxiliary power flows, this study shows an overview of the existing advancements in electric and hybrid vocational trucks, drawing on both academic and industrial instances, while explaining their different needs. Finally, this study analyzes efforts from both academia and industry to generate standardized duty cycles that can be used to assess the energy consumption of medium and heavy-duty vocational trucks, avoiding the need to replicate unique duty cycles that are measured on specific vehicles and environments.
Development of a Neural Network for Electric Vehicle Cabin Modeling towards advanced HVAC Management Strategies
Authors: Bartolucci Lorenzo , Cennamo Edoardo , Cordiner Stefano , Donnini Marco , Frezza Davide , Grattarola Federico , Mulone Vincenzo , Aimo Boot Marco , Giraudo Gabriele
Published: September 2024

The energy transition is a key challenge and opportunity for the transport sector. In this context, the adoption of electric vehicles (EVs) is emerging as a key solution to reduce environmental impact and mitigate problems related to traditional energy sources. One of the biggest problems related to electric mobility is the limited driving range it offers compared to the time needed for recharging, leading to what’s commonly known as “range anxiety” among users.

Significant part of the energy consumption of an electric vehicle is represented by the management of the HVAC system, which aim is to ensure the achievement and maintenance of thermal comfort conditions for the occupants of the vehicle. Currently the HVAC control logics are based on the pursuing of specific cabin setpoint temperature, which does not always guarantee the thermal comfort; more advanced human-based control logics allow to attain the thermal comfort in a zone around the subjects, as known as “heat bubble”, rather than acclimatizing the entire cabin, increasing the system efficiency and often reducing the thermal demand. It is therefore useful to develop a dynamic model that predicts and monitors the evolution of comfort parameters during the vehicle usage.

This study proposes to develop a simplified thermal model of the cabin system of a light duty commercial vehicle based on experimental data and numerical simulations, which is able to locally estimate the parameters of thermo-hygrometric comfort, and therefore allows a targeted management of the HVAC system with consequent energy optimization. First the cabin of a commercial BEV has been acquired and processed through reverse engineering techniques (3D scanning) in order to create the 3D CAD model; consequently, a CFD analysis based digital twin has been developed and validated with experimental data in different temperature conditions. Then the cabin system has been modeled with a neural network trained with results of CFD simulations, in order to replicate temperature behavior in the areas of interest.

The purpose of this modelling is to provide a starting point for the development of a reduced order model (ROM) that can be the basis of the development of advanced control logics to be integrated into the vehicle’s on-board computer system. Results show a good agreement between the CFD and simplified model (normalized Root Mean Square Error always below 0.29) and fast execution time (0.7 s on an 8 cores Intel i7 - 9700 processor) confirming the suitability of the approach for the proposed application.
Simulative Potential Analysis of Electrified Trailer Systems in Long-Haul Truck Applications
Authors: Knaup Lars , Beidl Christian
Published: September 2024

Abstract

As an important contributor to greenhouse gas emissions, the road freight sector plays a significant role when it comes to reaching global climate goals. Due to the requirements regarding payloads and ranges, the transition towards zero emissions is particularly challenging in this sector. A technical solution that can contribute to the reduction of greenhouse gas emissions are electrified semi-trailer systems. These vehicles can be combined with conventional tractor vehicles in order to reduce their fuel consumption and CO2 footprint, as well as with tractor vehicles with alternative powertrains to increase their driving range.

In this paper, a simulation study that evaluates the potentials of different configurations for such a system is performed. In the first part the general working principle of an electrified trailer is described. This includes a cloud based predictive energy management system that was used during the simulations. Based on a general vehicle model, the potentials of using electrified trailers in combination with a conventional tractor vehicle are evaluated. The study includes different powertrain configurations and battery systems. The different configurations were evaluated regarding their potential on fuel consumption reduction, greenhouse gas emissions and their influence on the total costs of ownership. Options like public fast charging and the use of a hybrid battery storage system that combines different battery cells were also evaluated.

Regardless of their specific configuration, the electrified trailer variants showed a significant potential for a reduction of fuel consumption and greenhouse gas emissions. The results also indicated the potential to achieve lower overall costs compared to a baseline vehicle with a conventional trailer.
Optimization of a Virtual H2 Engine Using a 1D Simulation Tool Targeting High Engine Performance along with Near-Zero Emission Levels
Authors: Marinoni Andrea , Montenegro Gianluca , Cerri Tarcisio , Della Torre Augusto , Onorati Angelo
Published: September 2024

Hydrogen engines are currently considered as a viable solution to preserve the internal combustion engine (ICE) as a power unit for vehicle propulsion. In particular, lean-burn gasoline Spark-Ignition (SI) engines have been a major subject of investigation, due to their reduced emission levels and high thermodynamic efficiency. Lean charge is suitable for passenger car applications, where the demand of mid/low power output does not require an excessive amount of air to be delivered by the turbocharging unit, but can difficulty be tailored in the field of high-performance engine, where the air mass delivered would require oversized turbocharging systems or more complex charging solutions. For this reason, the range of feeding conditions near the stochiometric is explored in the field of high-performance engines (20 BMEP), leading to the consequent issue of abatement of pollutant emissions. In this work, a 1D model is applied to the modeling of a four cylinder engine fueled with direct injection (DI) of hydrogen. The lambda condition has been chosen as the best compromise between performance and emission levels, tailoring the same power output of an equivalent SI gasoline engine. The main limitation experienced is the coupling with the turbocharging unit, which must guarantee the necessary boost pressure and air mass flow at all operating conditions. Low engine revolution speeds at full load have been experienced to be the most critical operating points. This work proposes an optimization of the engine layout, exploring the adoption of electrically assisted turbochargers as well as of a two-stage compression units, to reach the desired engine power output. A demanding driving cycle (the RTS-95) has been tested for all the engine configurations, where the low end revolution speed at full load is frequently reached. The different engine configurations are investigated in terms of performance, of energy required by the electrified units (which is around 600 Wh) as well as in terms of performance of the after-treatment system. Compared to a non-electrified configuration, the analysis shows that, where the lack of boost pressure is balanced by a reduction of the lambda, the usage of an electrified boosting system allows the achievement of both engine performance and reduction of pollutant emissions of around 11 mgNOx/km.
A Homogenization-Based Technique for a Simplified Numerical Finite Element Approach to Describe the Structural Behaviour of Cylindrical Cells Battery Pack
Authors: Mangeruga Valerio , Renso Fabio , Sassetti Riccardo , Giacopini Matteo
Published: September 2024

The continuously increasing demand for Battery Electric Vehicles, together with the customer requirement for higher ranges poses new challenges on the battery pack design. Drawing inspiration from aerospace design principles, wherein fuel tanks are integrated structurally into airframes to save weight and increase efficiency, structural battery packs are also experiencing growing use in the automotive field. In fact, when a structural battery pack is considered, significant weight savings can be achieved, potentially extending the vehicle range. Additionally, this weight saving could be further exploited to increase the battery pack size with respect to a non-structural battery pack, further enhancing the vehicle range without adding extra weight.

To address the complexity of integrating structural battery packs, Finite Element simulations are typically adopted to evaluate battery pack integrity and estimate its contribution to the structural behaviour of the overall vehicle. However, the detailed modelling of large number of cells and their interactions with components like cell carriers, busbars, and plates is computationally intensive. To overcome this limit, this contribution proposes a methodology to derive a simplified model of the cells module, deriving an equivalent homogeneous orthotropic material.

The results of this simplified approach have been compared to the results obtained from a complete model considering all the individual cells and all related components. The reduced computational effort resulting from the proposed methodology makes it suitable for integration into a more complex full vehicle model. This enables an optimization of the overall design, leading to possible significant improvements in vehicle performance, range and costs.
Investigating the Future of Road Freight Transport in Europe under Different Scenarios
Authors: SAAFI Mohamed Ali
Published: September 2024

Fighting climate change has become a major task worldwide. Alongside the United States and China, Europe is considered as one of the biggest greenhouse gases (GHG) emitters. Therefore, the European Union (EU) has set long term strategies to reduce emissions. One of the key energy sectors to emit greenhouse gases is transportation. In this context, EU has turned its eye toward cutting emissions from the transport sector and has recently put its stamp of approval on a reworked law banning all new sales of internal combustion engine (ICE) vehicles from 2035. Despite representing only 2% of the vehicles on the road, trucks account for more than a quarter of road transport emissions in the EU and have been increasing every year since 1990. In order to investigate the impact of transportation projected policies on the heavy-duty sector, we develop the Mobility and Energy Transportation Analysis (META) Model, a python-based model to project market penetration of conventional and alternative fuel technologies, energy demand and greenhouse gas (GHG) emissions. Moreover, we investigate the impact of introducing e-fuels-produced through a process involving carbon capture and hydrogen production from renewable energy- as a refueling option for ICE conventional vehicles. Adding to battery electric vehicles and fuel cell electric vehicles, META explores the opportunities of Mobile Carbon Capture (MCC) in decarbonizing the heavy-duty sector and penetrating the market shares up to 2050. The study shows that MCC could represent an economically promising solution to decarbonize the heavy-duty sector, through its decreased total cost of ownership (TCO) and marginal abatement cost (MAC) values compared to battery electric trucks (BETs) and fuel cell electric trucks (FCETs) until 2035.
Emission Optimization of the Cold Start Behavior of a CNG Engine with Electrically Heated Catalyst and Secondary Air Injection
Authors: Noone Patrick , Herold Tim , Beidl Christian
Published: September 2024

Decarbonization and a continuous reduction in exhaust emissions from combustion engines are key objectives in the further development of modern powertrains. In order to address both aspects, the DE4LoRa research project is developing an innovative hybrid powertrain that is characterized by the highly flexible combination of two electric motors with a monovalent compressed natural gas (CNG) engine. This approach enables highly efficient driving in purely electric, parallel and serial operating modes. The use of synthetic CNG alone leads to a significant reduction in CO2 emissions and thus in the climate impact of the drivetrain. With CNG-powered engines in particular, however, methane and other tailpipe emissions of climate gases and pollutants must also be minimized. This is possible in particular through efficient exhaust gas aftertreatment and an effective operating strategy of the powertrain. This publication presents measurement results that examine the critical aspect of cold starts. The engine is operated with a three-way catalyst with a coating specially tailored to CNG as well as an electrically heated disk and secondary air injection. The powertrain operating strategy makes it possible to preheat the catalyst when the engine is not running, which enables the catalyst to reach higher temperatures prior to the engine start, thus effectively reducing methane slip and other emissions during cold start. The combination of electrical heating power, secondary air mass flow and pre-heating duration are three of the factors in the optimization carried out here. Added to this is an analysis of the most efficient and low-emission engine start using a serial operating mode.
Development of a NG Engine Predictive Simulation Model and Investigation of Engine Performances under Hydrogen-Blended Operation
Authors: Baratta Mirko , Di Mascio Valerio , Misul Daniela , Marinoni Andrea , Cerri Tarcisio , Onorati Angelo
Published: September 2024

Hydrogen-powered mobility is believed to be crucial in the future, as hydrogen constitutes a promising solution to make up for the non-programmable character of the renewable energy sources. In this context, the hydrogen-fueled internal combustion engine represents one of the suitable technical solution for the future sustainable mobility. In a short-term perspective, the development of the green hydrogen production capability and distribution infrastructure do not allow a substantial penetration of pure hydrogen IC engines. For this reason, natural gas – hydrogen blends can represent a first significant step towards decarbonization, also determining a trigger effect on the hydrogen market development. The present paper is focused on the analysis of the combustion and performance characteristics of a production PFI natural gas engine, run on blends with 15% in volume of hydrogen (HCNG). More specifically, a fuel-flexible, predictive 1D simulation model has been developed within the Gasdyn code and validated against experimental data, under natural-gas operation. The model features the application of a predictive combustion model, which intrinsically accounts for the fuel burning characteristics through the specification of its laminar burning speed. The model has then been applied to the HCNG fueling case, with no changes in the combustion model settings, and showed rather good accuracy, thus demonstrating its fuel flexibility. The model was then used as a digital twin of the real engine, and the engine calibration was optimized in order to fully exploit the potential benefits of the hydrogen blending, with no or minor modification of the engine design with respect to a production spark ignition engine.
Optimizing Sustainable Energy Transition: A System Dynamics Approach for Biodiesel Integration in the Galapagos Islands
Authors: Gutierrez Marcos , Taco Diana
Published: September 2024

The Galapagos Islands have a protected marine reserve that currently gets most of its energy—over 80%—from fossil fuels like diesel. This reliance on fossil fuels is a significant issue because it impacts the environment and sustainability of the region. Understanding this heavy dependence is important for exploring alternatives that can provide cleaner energy. This paper introduces a new simulation model based on system dynamics to explore the effects of completely replacing fossil fuels with biodiesel as a short-term solution. The simulation uses current official data for the Galapagos Islands and connects different factors to calculate their effects all at once. Our goal is to identify the social, economic, energy-related, and environmental factors that make biodiesel a better choice than the currently used fossil fuels. We aim to find a way to keep the energy supply stable, as it mainly depends on internal combustion engines, while also quickly providing cleaner and greener energy with the resources we already have. Biodiesel can completely replace fossil fuels as an immediate short-term solution in the Galapagos Islands, providing a viable and advantageous option for energy supply that optimizes economic, social, energetic, and environmental conditions. With an adoption rate of 0.003—meaning that 3 out of every 1,000 people who currently use diesel switch to biodiesel each year—it is possible to establish biodiesel as the main fuel over a period of 5 years. In addition to using biodiesel as the only fuel source, within 5 years, it could cost 31.7% less if locally produced compared to diesel based on international prices. By 2050, CO2 emissions could drop from 8 million tons to 1 million tons. Our simulation, using real data, shows that adopting biodiesel within the current infrastructure is both viable and beneficial. It optimizes economic, social, energy-related, and environmental factors. We recommend this approach before adopting new technologies that claim zero CO2 emissions, as their potential environmental impacts are still unknown.
Investigation of Thermal Influences on Wear Behavior in Geared Transmissions
Authors: Grabovic Eugeniu , Ciulli Enrico , Artoni Alessio , Gabiccini Marco
Published: September 2024

Geared automotive and aerospace transmissions are one of the most critical systems regarding wear. Limiting wear is of paramount importance to improve sustainability by reducing replacements that lead to increased waste and energy consumption for re-manufacturing. Simulation of gears including the wear effect can be very useful for the design of new more efficient and compact gears. Thermal effects may play a decisive role in the wear phenomena and should be included in the models used for simulations.

In this study, some tests are conducted on a pin-on-disk apparatus under varying temperatures to assess its influence on steel-to-steel wear rate. A modified Archard law is used for wear estimation which includes the experimentally derived parameters accounting for thermal effects. This model is then coupled with a loaded tooth contact analysis (LTCA) tool to obtain accurate predictions of the contact pattern, as well as the instantaneous load shared by the mating teeth pairs during the meshing cycle.

This coupled simulation framework is then employed to carry out simulations of wear evolution during the lifespan of a gear pair. A comparison between wear simulations using a constant wear coefficient and one incorporating temperature dependency is presented. The wear law as function of temperature is scaled to account for boundary lubrication condition. Results put in evidence a limited impact of the local temperature on wear with this preliminary approach. The differences however increase with the number of working cycles.
Mitigating Thermal Stresses in Diesel Engine Pistons through Semitransparent Ceramic Coatings
Authors: Gutierrez Marcos , Taco Diana
Published: September 2024

The current investigation delves into the thermal stresses encountered by internal combustion engine pistons during the combustion process and explores the impact of high heat transfer through metallic engine components. The study focuses on a thermal analysis of a diesel engine piston model, incorporating a semitransparent ceramic coating on its surface. The research simulates temperature profiles on both the top surface of the piston and its substrate. The model incorporates an internal heat source, its magnitude calculated based on the coating's heat radiation absorbance values. The investigation considers Aluminum, and Titanium ceramic-based coatings with varying heat flow duration. Comparative analysis involves assessing the results of the numerical solution of the heat equation, incorporating the internal heat source function derived from experimentally measured absorbance values of the coatings’ material. Unlike prior studies that primarily relied on evaluating temperature profiles based on ceramic coating thermoconductivity properties, this research highlights the interaction of heat flux with defined optical properties (absorbance) in the coating, imparting semitransparency. This property leads to heat accumulation within the coating. Simulation outcomes indicate that the absorbance-driven internal heat source significantly reduces heat transfer to the substrate compared to considerations based solely on thermoconductivity properties. The study introduces a mathematical model validated through numerical solutions of a differential equation of a semitransparent heat-insulating coating. The findings demonstrate the coating's ability to enhance heat reduction compared to coatings lacking heat radiation absorbance capabilities.