bluuebunny/crossref_metadata_2025 huggingface dataset:
Application and analysis of a model with environmental transmission in a periodic environment
Authors: Fan Gaohui , Li Ning
Published: August 2023

The goal of this paper is to introduce a non-autonomous environmental transmission model for most respiratory and enteric infectious diseases to study the impact of periodic environmental changes on related infectious diseases. The transmission and decay rates of pathogens in the environment are set as periodic functions to summarize the influence of environmental fluctuations on diseases. The solutions of the model are qualitatively analyzed, and the equilibrium points and the reference criterion, $ R_0 $, for judging the infectivity of infectious diseases are deduced. The global stability of the disease-free equilibrium and the uniform persistence of the disease are proved by using the persistence theory. Common infectious diseases such as COVID-19, influenza, dysentery, pertussis and tuberculosis are selected to fit periodic and non-periodic models. Fitting experiments show that the periodic environmental model can respond to epidemic fluctuations more accurately than the non-periodic model. The periodic environment model is reasonable and applicable for seasonal infectious diseases. The response effects of the periodic and non-periodic models are basically the same for perennial infectious diseases. The periodic model can inform epidemiological trends in relevant emerging infectious diseases. Taking COVID-19 as an example, the sensitivity analysis results show that the virus-related parameters in the periodic model have the most significant influence on the system. It reminds us that, even late in the pandemic, we must focus on the viral load on the environment.
Pinning synchronization of dynamical neural networks with hybrid delays via event-triggered impulsive control
Authors: Yi Chengbo , Guo Rui , Cai Jiayi , Yan Xiaohu
Published: August 2023

In this study, a new event-triggered impulsive control strategy is used to solve the problem of pinning synchronization in coupled impulsive dynamical neural networks with hybrid delays. In view of discontinuous coupling terms and system dynamics, the inner delay and the impulsive delay are both investigated. Compared with the traditional pinning impulsive control, event-triggered pinning impulsive control (EPIC) generates impulse instants only when an event occurs, and is therefore more in line with practical applications. In order to deal with the complexities of mixed delays, some generalized inequalities related to hybrid delays based on Lyapunov functions are proposed, which are subject to the designed event-triggered rule. Then, in order to ensure network synchronization, linear matrix inequalities (LMIs) can provide some sufficient conditions with less conservatism while a proposed event-triggered function could successfully eliminate Zeno behavior. In addition, numerical examples are presented to prove the feasibility of the presented EPIC method.
Producing Structural High Integrity Castings with Minimum Carbon Footprint with the Comptech-Rheocasting Process
Authors: Hartlieb Martin , Tawil Jean Claude , Bergeron Stephane , Jansson Per
Published: August 2023

Structural high vacuum die casting has been growing significantly over the past decades. It is typically done with special (primary type) alloys, special melt treatment practices, high vacuum, a carefully engineered die casting process applying many best practices in our industry. Structural die castings are growing in size and complexity and die casting machines are getting bigger and bigger - and those castings are becoming a significant challenge with current technologies. It was now found that Rheocasting - a process of preparing a semi-solid slurry (with 30-45% solid fraction) that is injected slower and in a laminar way into the cavity, can take structural die casting to completely new heights, enable the casting of parts that would otherwise be impossible to cast and at the same time reduce or eliminate some of the current problems of structural die casting. With Rheocasting, lower purity (secondary) aluminum alloys can be used and excellent properties can be achieved as cast and heat treated (T5, T6/7). Rheocasting has had a breakthrough in the telecom and other industries, but it has now been optimized to become an essential tool in the toolbox of making structural castings. This paper shows the developments that lead to the successful series production of a large (about 4’ long) hinge pillar for an Electric Vehicle (EV). It explains the challenges and how they were overcome, and some of the possibilities of the process regarding alloys, heat treatments and achievable properties. It also shows how Rheocasting can help die casters produce more complex (thin and thick walled) and very large castings with the highest integrity. It can replace structural low-pressure permanent mold (LPPM) castings and reduce wall thickness, improve tolerances and make them more economical. Rheocasting can enable die casters to enter this new market of structural castings including Gigacastings, produce parts previously thought impossible to cast (and on much smaller machines than thought), and expand the growing structural die casting market even faster and further.
Performance and Fundamental Differences between Rheocast and High-Pressure Vacuum Die Cast Al-Si-Mg Alloys
Authors: Breton Francis , Fourmann Jerome
Published: August 2023

The Al-Si-Mg family is the preferred group of casting alloys due to their excellent castability, good mechanical properties and corrosion resistance. The ENAC-AlSi7Mg0.3 (A356) alloy has been used for decades to produce structural parts such as automotive wheels or suspension parts. However, this alloy cannot be used for high pressure die casting (HPDC) due to die soldering issues. Casting parameters in rheocasting differs greatly from those in HPDC. The lower injection temperature and lower intensification pressure reduce the reactivity between the mould and the aluminium. This lower interaction allows the injection of permanent mould alloys using HPDC. The objective of this work is to compare current structural alloys with rheocasting. A wide range of alloys in the Al-Si-Mg (-Mn) family were cast using the RheometalTM semi-solid technology in addition to ENAC-AlSi7Mg0.3 (A356) used as a comparison basis. Firstly, it was proven that ENAC-AlSi7Mg0.3 (A356) can successfully be cast using rheocast HPDC. Secondly, the impact of magnesium and manganese were studied. Magnesium has a great impact on strength while manganese can further improve the strength by controlling the iron phase morphology. This work proves that various types of alloys can be cast using rheocast HPDC.
Retrieval of a sewing needle from the third part of the duodenum with overtube endoscopy
Authors: Lakmal Chamila , Liyanage Indunil , Vignesvaran Sanjeev , Pathirana Aloka
Published: August 2023

No abstract available
Metastatic duodenal carcinoma presenting as severe anaemia and extensive bilateral lower limb deep venous thrombosis
Authors: Ranatunga Krishna , Jayasekera Krishantha
Published: August 2023

No abstract available
Knowledge, attitude and practices on insulin therapy among patients with type 1 diabetes
Authors: Jagodage Hemamali , Sandamali Priyanthika , Lenora Janaka
Published: August 2023

Introduction: The incidence of type 1 diabetes mellitus (T1DM) is increasing worldwide. Daily administration of multi-dose or single-dose Insulin therapy is the cornerstone in the treatment of T1DM. The recent studies highlighted the gap in knowledge, attitude, and practice (KAP) towards insulin therapy for the optimal control of hyperglycemia T1DM. The study aimed to assess knowledge, attitudes, and practices regarding insulin therapy among T1DM patients attending the diabetic clinic, Teaching Hospital Karapitiya (THK).Methods: A cross-sectional descriptive study was conducted using an interviewer-administered questionnaire to elicit socio-demographic information and KAP towards insulin therapy. A total of 62 attending the diabetic clinic at THK were recruited.Results: The study population consisted of 91.9% early young adults (ages 18-25 years) while the remainder represented late young adults (ages 26 - 30 years). A good knowledge, attitude and practice were seen in 61.3%, 62.9% and 38.1% of the patients respectively. Age, level of education, duration of DM, regular clinic visits and favourable attitudes were associated with good knowledge whereas level of education, duration of DM, regular clinic visits and good knowledge were associated with favourable attitudes. Duration of DM and regular clinic visits were the only factors associated with good practices. Higher level of knowledge or higher level of education were not associated with good practices towards insulin therapy (p>0.05).Conclusions & recommendations: Though majority had good knowledge and attitudes, practices were unsatisfactory in the majority of them. Self-management education and training giving special attention to psychosocial aspects of living to improve self-care behaviour are recommended to address the gap between knowledge and practices.
Diplomate in Medical Laboratory Immunology Certification Examination: A New Chapter for Medical Laboratory Immunology
Authors: Khanolkar Aaruni , Spiczka Amy , Bonfield Tracey L , Alexander Thomas S , Schmitz John L , Boras Diana , Fong Karen , Nandiwada Sarada L , Miller Gerald C , Tebo Anne E
Published: August 2023

It is indeed a privilege to be an immunologist in what is arguably the golden age of immunology. From astounding advances in fundamental knowledge to groundbreaking immunotherapeutic offerings, immunology has carved out an enviable niche for itself in basic science and clinical medicine. The need and the vital importance of appropriate education, training, and certification in clinical immunology was recognized by the World Health Organization as far back as 1972. In the United States, Ph.D. scientists with board certification in medical laboratory immunology have served as directors of high-complexity Clinical Laboratory Improvement Amendments– and College of American Pathologists–certified clinical immunology laboratories since 1977. From 1977 to 2017, board certification for medical laboratory immunology was administered by the American Society for Microbiology through the American Board of Medical Laboratory Immunology examination. The American Board of Medical Laboratory Immunology examination was phased out in 2017, and in the fall of 2019, the American Society for Clinical Pathology (ASCP) Board of Certification (BOC) examination committee took on the responsibility of developing a new doctoral-level certification examination for medical laboratory immunology. This transition to the ASCP BOC represents a well-deserved and much-needed recognition of the rapid advances in and the highly specialized nature of medical laboratory immunology and its ever-increasing relevance to patient care. This new ASCP BOC certification is called the Diplomate in Medical Laboratory Immunology, and, as of April 1, 2023, it is now available to potential examinees. In this report, we describe the examination, eligibility routes, and potential career pathways for successful diplomates.
Metacognitive interpersonal therapy-eating disorders versus cognitive behavioral therapy for eating disorders for non-underweight adults with eating disorders: study protocol for a pilot pre-registered randomized controlled trial
Authors: Fioravanti Gloria , Nicolis Martina , MacBeth Angus , Dimaggio Giancarlo , Popolo Raffaele
Published: August 2023

Eating disorders (ED) are serious disorders characterized by an alteration of eating habits and excessive concern about weight and body shapes (Fairburn, 2002), accompanied by significant impairment inequality of life, high mortality rates and serious organic consequences (Jenkins et al., 2011; Treasure et al., 2015; 2020). Although evidence-based psychological therapies for nonunderweight ED presentations such as cognitive behavioral therapy for eating disorders (CBT-ED) are widely available, there is substantial scope for improvements, particularly in terms of efficacy and adherence. One option is to develop interventions to address elements of pathology not fully addressed by existing empirical supported treatments, such as incorporating techniques aimed at addressing interpersonal problems and personality disorder features into existing treatment delivery. We adapted Metacognitive Interpersonal Therapy, a psychological intervention supported by evidence for treating personality disorders and integrated it with existing CBT techniques for eating disorders (MIT-ED). MIT-ED targets aspects of ED that are not included in the transdiagnostic CBT-E model such as poor metacognition, or maladaptive interpersonal schemas. This is a pre-registered (Protocol number: 0000781) pilot randomized clinical trial aimed at assessing acceptability and feasibility of MIT-ED and establishing preliminary evidence of effectiveness for future larger studies. Twenty patients (10 in each arm) will be randomized to 20 sessions of individual psychotherapy, either MIT-ED or CBTE. Repeated follow-ups will be collected up to 24 months. Participants are recruited at a private outpatient clinic for ED treatment. Acceptability will be assessed via session attendance, completion rates and preliminary outcomes. The primary outcome is ED pathology assessed with the Eating Disorder Examination Questionnaire-6. Other ED outcomes assessed will be eating disorder attitudes, clinical impairment and binge eating pathology. Secondary treatment outcomes are anxiety, depression, and global symptomatology. We will also assess emotional awareness, emotion regulation and therapeutic alliance. Based on previous studies of MIT for personality disorders we hypothesize that MIT-ED will be acceptable to patients, evidenced by high treatment adherence and retention. We hypothesize that MIT-ED will be associated with reductions in eating disorder pathology, at least equivalent to CBT-E. Results will be used to inform the study design, sampling, likely effect sizes and choice of outcome measures for future larger trials of MIT-ED in ED samples.
Predictive Score for Dengue Infection with Complete Blood Count Parameters, Including the Monocyte Distribution Width: A Retrospective Single-Center Derivation and Validation Study
Authors: Poottasane Naiyana , Phornprasitsaeng Pharkchawis , Onthong Yupapin , Sinthana Thurdsak , Limvorapitak Wasithep
Published: August 2023

Early detection of dengue virus infection will lead to proper management and reduction in morbidity/mortality. Monocyte distribution width (MDW) was recently approved for use in the early detection of sepsis. Because monocytes are involved in the innate immune system against viral infection, we sought to determine changes in MDW to develop and validate a new predictive score for dengue viral infection. This study included patients who presented with symptoms or signs related to dengue infection and who had a complete blood count and dengue investigation performed during September 2019 to May 2020. The proportion of dengue infection was 29.5% in the current study. The MDW was significantly higher in dengue infection (median, 29.7 versus 24.2; P < 0.001). We then randomly separated patients into training and validation cohorts. Independent predictive factors of dengue infection were white blood cells < 4 × 109/L (score 1), platelets < 100 × 109/L (score 1), and MDW > 24 (score 1). Clinical features were not significantly predictive of dengue infection. The areas under the receiver operating characteristic curve (95% CI) of the prognostic score were 0.839 (0.779–0.899) in the training cohort and 0.742 (0.674–0.811) in the validation cohort. With a cutoff score ≥ 1, the sensitivity and specificity of the scores were 92.2% and 40.8% in the training cohort and 88.9% and 44.1% in the validation cohort, respectively. We concluded that MDW increases with dengue infection and MDW could easily be incorporated in the predictive scores for dengue infection.
Comparison of Modern Powertrains Using an Energy Model Based on Well-to-Miles Analysis
Authors: Falfari Stefania , Mariani Valerio , Bianchi Gian Marco , Cazzoli Giulio
Published: August 2023

The need to reduce carbon dioxide emissions from motor vehicles pushes the European Union towards drastic choices on future mobility. Despite this, the engines of the “future” have not yet been defined: the choice of engine type will undoubtedly depend on the type of application (journey length, availability of recharging/refueling facilities), practical availability of alternative fuels, and electricity to recharge the batteries. The electrification of vehicles (passenger and transportation cars) may be unsuitable for several aspects: the gravimetric energy density could be too low if the vehicle has to be lightweight, must achieve a high degree of autonomy, or needs a very short refueling time. To compare the sustainability of various partially or fully electric propulsion systems equipped with thermal engines powered by alternative fuels (e-fuels, hydrogen, green methane, etc.) or powered by fuel cells, it is necessary to consider the entire life cycle of the vehicle, including the production stage of the “propellant”. This methodology, the well-known Well-to-Miles analysis, is the basis of the energy model presented in this work and developed with Matlab code. The energy model is able to consider the overall energy cost required by a vehicle to complete a specific journey starting from the production of the fuel that powers it (electricity included). The model is validated by comparison with reported carbon dioxide emissions and fuel consumption data for two modern cars, one powered by a petrol engine, the other plug-in. Finally, a comparison between the declared data and the simulation results for a fuel cell vehicle and a pure battery vehicle is reported. The model is a valuable tool for energy assessment (consumption, emissions) of various propulsion units suitable for making a specific trip.
Simulation of CNG Engine in Agriculture Vehicles. Part 1: Prediction of Cold Start Engine-Out Emissions Using Tabulated Chemistry and Stochastic Reactor Model
Authors: Siddareddy Reddy Babu , Franken Tim , Leon de Syniawa Larisa , Pasternak Michal , Prehn Sascha , Buchholz Bert , Mauss Fabian
Published: August 2023

Worldwide, there is the demand to reduce harmful emissions from non-road vehicles to fulfill European Stage V+ and VI (2022, 2024) emission legislation. The rules require significant reductions in nitrogen oxides (NOx), methane (CH4) and formaldehyde (CH2O) emissions from non-road vehicles. Compressed natural gas (CNG) engines with appropriate exhaust aftertreatment systems such as three-way catalytic converter (TWC) can meet these regulations. An issue remains for reducing emissions during the engine cold start where the CNG engine and TWC yet do not reach their optimum operating conditions. The resulting complexity of engine and catalyst calibration can be efficiently supported by numerical models. Hence, it is required to develop accurate simulation models which can predict cold start emissions.

This work presents a real-time engine model for transient engine-out emission prediction using tabulated chemistry for CNG. The engine model is based on a stochastic reactor model (SRM) which describes the in-cylinder processes of spark ignition (SI) engines including large-scale and low-scale turbulence, convective heat transfer, turbulent flame propagation and chemistry. Chemistry is described using a tabulated chemistry model which calculates the major exhaust gas emissions of CNG engines such as CO2, NOx, CO, CH4 and CH2O.

By best practice, the engine model parameters are optimized by matching the experimental cylinder pressure and engine-out emissions from steady-state operating points. The engine model is trained for a non-road transient cycle (NRTC) cold start at 25°C ambient temperature and validated for a NRTC cold start at 10°C ambient temperature. The trained model is evaluated regarding their feasibility and accuracy predicting transient engine-out emissions.
Thermodynamic and Tribological Analysis of an Innovative Mechanism for Reciprocating Machines
Authors: Georgitzikis Vasileios , Breda Sebastiano , Kalligeros Christos , Spitas Vasilios , Rogkas Nikolaos , Cicalese Giuseppe , D'Orrico Fabrizio , Tzouganakis Panteleimon , Fontanesi Stefano
Published: August 2023

Research and development studies regarding the internal combustion engines are, now more than ever, crucial in order to prevent a premature disposal for this application. An innovative technology is analyzed in this paper. The traditional slider-crank mechanism is replaced by a system of two ring-like elements crafted in such a way to transform the rotating motion of one element in the reciprocating motion of the other. This leads both to a less complex engine architecture and to the possibility to obtain a wide range of piston laws by changing the profile of the two cams. The relative motion of the cams is the peculiar feature of this engine and, due to this, alongside with the thermodynamic analysis, also the tribological aspects are investigated. 3D-CFD simulations are performed for several piston laws at different engine speeds to evaluate the cylinder pressure trace to be used as input data for the development of the tribological model. Moreover, the CFD results are analyzed in terms of engine performance to compare each piston law with the traditional crank law.
Effects of Engine Speed on Prechamber-Assisted Combustion
Authors: Palombi Lucia , Sharma Priybrat , Cenker Emre , Magnotti Gaetano
Published: August 2023

Lean combustion technologies show promise for improving engine efficiency and reducing emissions. Among these technologies, prechamber-assisted combustion (PCC) is established as a reliable option for achieving lean or ultra-lean combustion. In this study, the effect of engine speed on PCC was investigated in a naturally aspirated heavy-duty optical engine: a comparison has been made between analytical performances and optical flame behavior. Bottom view natural flame luminosity (NFL) imaging was used to observe the combustion process. The prechamber was fueled with methane, while the main chamber was fueled with methanol. The engine speed was varied at 1000, 1100, and 1200 revolutions per minute (rpm). The combustion in the prechamber is not affected by changes in engine speed. However, the heat release rate (HRR) in the main chamber changed from two distinct stages with a faster first stage to more gradual and merged stages as the engine speed increased. NFL imaging revealed that lower mean piston speed allowed for longer free jet propagation inside the combustion chamber resulting in faster and stronger HRR stages. At higher speeds, the jet-piston interaction started earlier and was dispersed in radial directions, resulting in a relatively prolonged HRR. Finally, the study emphasizes the importance of prechamber jet and piston interaction in shaping HRR.
Numerical Study on the Effect of Injector Nozzle Hole Number on Diesel Engine Performance under Plateau Conditions
Authors: Zhao Junliang , Yang Ruomiao , Yan Yuchao , Ou Juan , Liu Zhentao , Liu Jinlong
Published: August 2023

Diesel engines operated at high altitudes would experience performance degradation due to the fuel-air amount mismatch, resulting in combustion deterioration. Technologies that supplement oxygen concentration, such as intake oxygen enrichment, turbocharging and the addition of oxygenated fuel additives, can help restore performance at high altitudes, but each has its own limitations Operating diesel engines at high altitudes still generates extremely lean fuel-air mixtures, making the improved utilization of excess air the most economically efficient approach to optimize engine performance under such conditions. The objective of this paper is to investigate the effects of injector nozzle-hole numbers on diesel engines operated at high altitudes, a topic that has been limitedly discussed in existing literature, with the aim of enhancing understanding regarding the potential of this cost-effective approach and aiding in the design of a cooperative approach between oxygen concentration supplementation techniques and better oxygen utilization techniques, ultimately optimizing engine performance at high altitudes. The results suggest that increasing the number of nozzle-holes enhances fuel-air mixing, leading to improved combustion quality and enhancing the engine’s adaptability to altitude. However, at extremely high altitudes, such as altitudes exceeding 3000 meters, configurations with a larger number of nozzle-holes still exhibit high concentrations of incomplete combustion products, such as soot emissions, in the exhaust. This reduced combustion efficiency is mainly attributed to the longer spray penetration length at high altitudes, which causes intensified spray impingement on the cavity wall, subsequently resulting in inefficient combustion of the fuel flowing into the squish zone during spray impingement. This inefficiency may be mitigated by optimizing the shape of the combustion chamber. It is worth noting that increasing the number of nozzle-holes can also lead to a higher pressure rise rate. Considering that high altitude operations already result in a higher pressure rise rate, further increasing the nozzle-hole number may exceed the allowable threshold and increase the likelihood of engine component failure. Consequently, the strength of engine components becomes a limiting factor when attempting to increase the number of nozzle-holes for improved engine altitude adaptation.
Engine Efficiency Measurements Using a 100 kHz Radio Frequency Corona Igniter
Authors: Ricci Federico , Papi Stefano , Battistoni Michele , Zembi Jacopo , Dal Re Massimo , Grimaldi Carlo
Published: August 2023

Conventional spark-ignition engines are currently incapable of meeting rising customer performance demands while complying with even stringent pollutant-emissions regulations. As a result, innovative ignition systems are being developed to accomplish these targets. Radio-Frequency corona igniters stand out for their ability to accelerate early flame growth speed by exploiting the combined action of kinetic, thermal and transport effects. Furthermore, a volumetric discharge enables the promotion of combustion over a wide area, as opposed to the local ignition of traditional spark.

The present work wants to evaluate the advantages of a Streamer-type Radio Frequency corona discharge at about 100 kHz with respect to those of traditional spark igniter. To explore the corona ignition behavior, experimental campaigns were performed on a three-cylinder spark-ignition engine fueled with gasoline, at condition of stochiometric mixture, low speed, two different loads and by varying the igniter control parameters, i.e. driving voltage and activation time. The igniters’ performance was investigated using indicating and efficiency analysis. The latter was accomplished by estimating engine fuel consumption and the delivered engine torque.

When compared to traditional spark, the corona device showed substantial enhancement of the effective efficiency up to 2%, with improvement of delivered torque of about 10%, and combustion stability up to 40%.
Effects of Pre-Chamber Internal Shape on CH
4
-H
2
Combustion Characteristics Using Rapid-Compression Expansion Machine Experiments and 3D-CFD Analysis
Authors: Feng Yixin , Yamazaki Ryo , Sok Ratnak , Kusaka Jin
Published: August 2023

Pre-chamber (PC) natural gas and hydrogen (CH4-H2) combustion can improve thermal efficiency and greenhouse gas emissions from decarbonized stationary engines. However, the engine efficiency is worsened by prolonged combustion duration due to PC jet velocity extinction. This work investigates the impact of cylindrical PC internal shapes to increase its jet velocity and shorten combustion duration. A rapid compression and expansion machine (RCEM) is used to investigate the combustion characteristics of premixed CH4 gas. The combustion images are recorded using a high-speed camera of 10,000 fps. The experiments are conducted using two types of long PC shapes with diameters φ=4 mm (hereafter, longφ4) and 5 mm (hereafter, long φ5), and their combustions are compared against a short PC shape (φ=12 mm). For all designs of the PC shapes, the PC holes are 6 with 2 mm in diameter. Initial recorded results using only CH4 show that jet extinction does not occur using the short and long 5mm types. The combustion duration of φ=4 mm PC is the shortest compared to the short-type and 5 mm PC. With CH4-H2 blending (0%H2, 10%H2, 20%H2) and 4 mm shape, the combustion durations of 10%H2 and 20%H2 can be shortened compared to the CH4-only case (0%H2). However, the jet extinction probability is not zero.

3D-CFD combustion simulations are performed using CONVERGE software, and a 1/6 sector-mesh, GRI-Mech 3.0, G-equation combustion, and law-of-wall models are utilized in conjunction with RNG k-epsilon turbulence model. Simulated in-cylinder pressure and burning rate are validated against the recorded data. PC jet velocity, turbulent kinetic energy (TKE) of the main chamber, PC jet temperature, total heat loss in PC, and PC heat loss rate of 12 mm, 4 mm, and 5 mm are compared. Experimental combustion images and 3D-CFD temperature distribution with and without H2 blending are also reported. The results show that long PC types can accelerate the jet velocity and shorten combustion duration. The jet extinction can be prevented by designing a small PC diameter area larger than the nozzle’s cross-sectional area. With H2 blending, laminar burning velocity increases, and the jet ejection timing can be advanced. The result shows that the combustion duration can be shortened by 15 degrees using CH4-20%H2 against CH4 only.
Theoretical Analysis of Multi-Zone and Transported Probability Density Function Approaches Applied to Low Temperature Combustion Process
Authors: Maroteaux Fadila , Mancaruso Ezio , Pommier Pierre-Lin , Vaglieco Bianca Maria
Published: August 2023

Electrification of transport, together with the decarbonization of energy production are suggested by the European Union for the future quality of air. However, in the medium period, propulsion systems will continue to dominate urban mobility, making mandatory the retrofitting of thermal engines by applying combustion modes able to reduce NOx and PM emissions while maintaining engine performances. Low Temperature Combustion (LTC) is an attractive process to meet this target. This mode relies on premixed mixture and fuel lean in-cylinder charge whatever the fuel type: from conventional through alternative fuels with a minimum carbon footprint. This combustion mode has been subject of numerous modelling approaches in the engine research community. This study provides a theoretical comparative analysis between multi-zone (MZ) and Transported probability density function (TPDF) models applied to LTC combustion process. The generic thermo-kinetic balances for both approaches have been analyzed in term of similarities. Only onion-skin for MZ models have been considered in this study. The governing assumptions linked to sub-models for each approach to describe mixing process for TPDF and interzonal heat and mass transport for MZ are discussed. This step identifies the calibrated model parameters for each approach and their effects on the accuracy in predicting LTC mode simulations. This work shows that the transported probability density function model has fewer parameters to calibrate compared to multi-zone model. Transported probability density function seems easier to use for LTC process.
Numerical Modeling of Hydrogen Combustion Using Preferential Species Diffusion, Detailed Chemistry and Adaptive Mesh Refinement in Internal Combustion Engines
Authors: Gomez-Soriano Josep , Sapkota Pradeep , Wijeyakulasuriya Sameera , D'Elia Matteo , Probst Daniel , Viswanathan Veeraraghavan , Olcina-Girona Miguel , Novella Ricardo
Published: August 2023

Mitigating human-made climate change means cutting greenhouse gas (GHG) emissions, especially carbon dioxide (CO2), which causes climate change. One approach to achieving this is to move to a carbon-free economy where carbon emissions are offset by carbon removal or sequestration. Transportation is a significant contributor to CO2 emissions, so finding renewable alternatives to fossil fuels is crucial. Green hydrogen-fueled engines can reduce the carbon footprint of transportation and help achieve a carbon-free economy. However, hydrogen combustion is challenging in an internal combustion engine due to flame instabilities, pre-ignition, and backfire. Numerical modeling of hydrogen combustion is necessary to optimize engine performance and reduce emissions. In this work, a numerical methodology is proposed to model lean hydrogen combustion in a turbocharged port fuel injection (PFI) spark-ignition (SI) engine for automotive applications. The numerical method is based on 3D Computational Fluid Dynamics (CFD) simulations where Hydrogen injection is modeled using a mass flow boundary condition in the intake port, preferential species diffusion is used to model fuel-air mixing, and a 12 species, 37 reactions reduced chemical kinetics mechanism is used to model combustion with a detailed chemistry solver. Results shows good validation against measured multiple cycle cylinder pressure data for several operating conditions including varying load and equivalence ratios. The conventional methodology to simulate multiple engine cycles consecutively can be time consuming, hence, this paper evaluates the concurrent perturbation method which allows for simulating multiple cycles simultaneously in significantly less wall clock time.
Numerical Analysis of Hydrogen Injection and Mixing in Wankel Rotary Engines
Authors: Moreno Cabezas Kevin , Vorraro Giovanni , Liu Xinlei , Menaca Rafael , Im Hong G. , Turner James W.G.
Published: August 2023

The Wankel rotary engine has been an attractive alternative for transportation due to its unique features of lightweight construction, small size, high power density, and adaptability to various fuels. This paper aims to investigate the performance of air-fuel mixing in a hydrogen-fuelled Wankel rotary engine using different fuelling strategies. To achieve this, 3D computational fluid dynamics (CFD) simulations were conducted using CONVERGE software on a prototype engine with a displacement of 225 cc, manufactured by Advanced Innovative Engineering UK. Initially, the simulations were validated by comparing the results with experimental data obtained from the engine fuelled with conventional gasoline under both motored and fired conditions. After validating the model, simulations were conducted on the premixed hydrogen engine combustion, followed by more detailed simulations of port fuel injection (PFI) and direct injection (DI) of hydrogen in the engine. The results indicate that hydrogen is a promising substitute for conventional carbon-based fuels in Wankel engines, as it can reduce carbon dioxide (CO2) emissions. The DI strategy has the potential to increase engine performance by improving volumetric efficiency and better controlling the fuel mass trapped in the combustion chamber. Injecting the fuel into the chamber guarantees mixture enrichment for combustion and generates charge stratification that reduces heat release rate and improves power generation. The reduced heat release rate also lowers heat transfer losses from flame-to-wall interaction, which greatly impacts Wankel engine efficiency. Lean mixtures have the potential to reduce nitrogen oxides (NOx) emissions in combustion. In summary, this study demonstrates the compatibility of hydrogen direct injection fuelling with the Wankel engine. The study provides important insights to improve the understanding of hydrogen application in this engine concept for future design and optimization of hydrogen injection configuration and strategy.
Applications of an Advanced Multiple Injection Calibration Strategy to Address Future Emission Legislation Challenges
Authors: Fellner Felix , Miyamoto Akiyasu , Joerg Christian , Kraus Christoph , Härtl Martin , Jaensch Malte
Published: August 2023

A novel algorithm-based approach is employed in this publication to calculate multiple direct injection patterns for spark ignition engines. The algorithm is verified by investigating the combustion and emission behavior of a single-cylinder research engine. State-of-the-art standard exhaust gas analyzers, a particle counter and an additional FTIR analyzer enable in-depth investigation of engine exhaust gas composition.

With the upcoming worldwide pollutant emission targets, the emission limits will be reduced while the test procedures’ requirements to the engine increase. Special attention to the engine-out emissions must be paid during cold-start, during which the aftertreatment system lacks sufficient pollutant emission conversion efficiency.

With advanced injection control, the engine-out emissions can be reduced and exhaust aftertreatment heat-up can be accelerated. Such injection strategies separate the injected fuel quantity over several injection events for different purposes, respectively. However, increasing effort for engine calibration prevents the full employment of the advantages of complex, multiple injection strategies.

The algorithm-based approach used in this publication facilitates automatic injection pattern generation, instead of calibrating the multiple injections based on conventional Design of Experiment methods that are associated with extensive engine testing. To adapt to different operation conditions, a reduced number of calibration parameters are introduced to efficiently identify beneficial injection patterns. Special focus is placed on optimizing the engine cold-start behavior in view on engine-out emissions and rapid exhaust heating. Consequently, investigations have been undertaken with the research engine cooled down to -7°C. Combustion imaging using an endoscopic optical access complement to the thermodynamic measurement data and visualize the influence of injection strategy on combustion. The presented results proof that the automatically calculated injection patterns facilitate combustion optimization.
Experimental-Numerical Analysis of Gasoline Spray-Wall Impingement at Ultra-High Injection Pressure for GCI Application
Authors: Viscione Davide , Silvagni Giacomo , Falfari Stefania , Bianchi Gian Marco , Ravaglioli Vittorio , Mariani Valerio , Allocca Luigi , Montanaro Alessandro , Meccariello Giovanni
Published: August 2023

Nowadays, in the perspective of a full electric automotive scenario, internal combustion engines can still play a central role in the fulfilment of different needs if the efficiency will be improved, and the tailpipe emission will be further limited. Gasoline Compression Ignition engines can offer a favourable balance between NOx, particulate, operating range. Stable operations are ensured by ultra-high gasoline injection pressure and tailored injection patterns in order to design the most proper local fuel distribution. In this context, engine simulations by means of CFD codes can provide insights on the design of the injection parameters, and emphasis must be placed on the capture of spray-wall impingement behaviour under those non-conventional conditions. This paper aims to analyse the spray-wall impingement behaviour of ultra-high gasoline spray using a combined experimental-CFD approach. The fuel is injected inside a vessel through a single-hole nozzle at GCI-like injection pressure (500-700 bar) against a metal surface. At the test bench, optical measures were performed by means of the Mie-scattering technique in order to capture the impact morphology. Furthermore, some synthetic features of the impact were calculated, namely the thickness and the width of the rebound cloud. In order to focus on the wall film formation mechanism, the tests were conducted at room temperature. Then, the experimental data were used to validate the CFD spray-wall impingement methodology and tuning.
Renewable Alternatives for Fossil Fuels in Non-Road Mobile Machinery: A Multicriteria Analysis
Authors: Dejaegere Quinten , Verhelst Sebastian
Published: August 2023

Non-Road Mobile Machinery (NRMM) incorporates a wide variety of machines not intended for the transport of passengers or goods on the road. This includes small gardening equipment, construction, mining, agricultural, and forestry machinery up to locomotives and inland waterway vessels, mostly using an internal combustion engine. NRMM was often overlooked and neglected in the past when considering pollutant and greenhouse gas emissions. Due to their high diversity, they are hard to categorize, resulting in a lack of available data. As emissions from road transport are being tackled by regulations, the emissions of NRMM become an increasing part of total transport emissions. An alternative to fossil fuels will be required for the energy supply of NRMM to fully commit to the CO2 reduction goals, and to fulfil the future requirements of legislators and public opinion. This study provides a report on the energy needs of different applications, mainly focusing on the larger machinery, as well as an overview of existing and expected technology. To conduct the analysis, a straddle carrier, excavator, locomotive, and inland water vessel were selected as case studies to cover a broad range of NRMM, ranging from 100kW to 1MW engines within different working environments. The intention is to match these, and similar applications, with the most appropriate currently available as well as future expected technology. A selection is made from the possibilities of different energy carriers, such as battery-electric, hydrogen, methane (LNG + CNG), ammonia, methanol, and HVO, in combination with a suitable energy converter, be it an electric motor, an internal combustion engine, a fuel cell or a hybrid system. A multi-criteria decision approach is used to analyse the performance of each option with the varying requirements of the applications in mind, covering environmental, technical, and economic aspects.
Sustainability of Advanced ICEs Based HEVs for Passenger Cars Fuelled with Alternative Fuels: A LCA Study in Comparison with BEV Technology
Authors: Della Ragione Livia , Meccariello Giovanni , Beatrice Carlo , Ricco Raffaele
Published: August 2023

A possible environmental assessment of sustainable vehicular transport is based on a comparative analysis through the LCA Life Cycle Analysis methodology of the entire vehicle’s life cycle. For this purpose, it could contribute to the choices of political decision-makers and investors in the sector of large infrastructure and industrial works. Therefore, the LCA activity is of fundamental importance for the estimation and analysis of the economic and social impacts through the comparative analysis of technological solutions in scenarios of “accelerated technological evolution” and/or “sustainable mobility”. The study could be designed for different vehicle segments to evaluate their efficiency and overall environmental sustainability also related to current social and political scenarios. Couples with electric and internal combustion vehicles of the same market segment and category may be compared. Furthermore, the comparative analysis is carried out during a PON Extreme research project by evaluating different scenarios and presenting the effect on the different factors of the technologies studied during project activities in terms of efficiency and reduction of the assessed impact. Globally the overall impact can be divided into: Well To Tank (WTT - “from the well to the tank”), due to the supply of primary energy to the vehicle (e.g. extraction of fossil fuel, production of biofuels, production of electricity, distribution), before this is used by the vehicle itself; Tank To Wheels (TTW - “from the tank to the wheels”), calculated according to the performance of the vehicle after it has been refueled and the vehicle production impact to manufacture and dispose the vehicle in all its components. Moreover, an Excel macro tool is developed to calculate and shows results based on the whole database capable to modify parameter and scenario to produce a variety of interesting future
On-Board Monitoring of Emissions in the Future Euro 7 Standard
Authors: Franco Vicente , Dilara Panagiota , Hennig Nils , Manara Dario , Forloni Fabrizio , Short Ian , Ligterink Norbert , Ehrly Markus , Kontses Dimitrios , Samaras Zissis
Published: August 2023

The proposed Euro 7 emission standard foresees that the emission behaviour of Euro 7 vehicles is monitored via an on-board monitoring (OBM) system. In Euro 7 vehicles, OBM systems will monitor the emissions of nitrogen oxides (NOX), ammonia (NH3) and particulate matter (PM) for every trip through a combination of measured and modelled data. Sensors employed to support on-board diagnostics (OBD) in current vehicles may be used to support OBM.

According to the Euro 7 OBM concept presented in this paper, OBM will serve a dual purpose: the first is to warn the user of a vehicle about the need to perform repairs on the engine or the pollution control systems when these are needed. If these repairs are not performed in a timely manner, the OBM system will be able to ultimately prevent engine restart, akin to the existing low-reagent driver warning system in some compression ignition vehicles. The second purpose of OBM is to monitor the compliance of vehicle types with the emission limits. To that end, OBM systems will calculate an approximation of the distance-specific trip emissions at the end of each trip. A random selection of these trips will then be periodically transmitted in an anonymous way to the authorities. This will allow them to compare average trip emissions for a particular vehicle type to the relevant limits.
HORIZON Europe Project AeroSolfd: GPF-Retrofit for Cleaner Urban Mobility
Authors: Rubino Lauretta , Mayer Andreas , Czerwinski Jan , Lutz Thomas , Larsen Lars , Engelmann Danilo , Lehmann Martin
Published: August 2023

Ultrafine particles, in particular solid sub-100 nm particles pose high risks to human health due to their high lung deposition efficiency, translocation to all organs including the brain and their harmful chemical composition; due to dense traffic, the population in urban environments is exposed to high concentrations of those toxic air contaminants, despite these facts, they are still widely neglected. Therefore, the EU-Commission set up a program for clean and competitive solutions for different problem areas which are regarded to be hotspots of such particles. HORIZON AeroSolfd is an EU project, co-funded by Switzerland that will deliver affordable, adaptable, and sustainable retrofit solutions to reduce exhaust tailpipe emissions from petrol engines, brake emissions and pollution in semi-closed environments. VERT, a Swiss based international industry organization, has a long research history in the field of nanoparticle filtration and it is in charge of reducing tailpipe emissions of gasoline vehicles by using the best available retrofit filtration technology (BAT). VERT will apply the newest high-efficient GPF technology in three high mileage fleets, in Germany, Switzerland and Israel. The project will also serve as a platform to continue research on PN emissions as well as on secondary emissions from GDI and PFI petrol engines. In addition, the “high emitter phenomena” will be further analysed with a NPTI testing campaign of 1000 gasoline vehicles, including GDI, PFI and GPF equipped vehicles.