bluuebunny/crossref_metadata_2025 huggingface dataset:
Impact of QCD Jets and Heavy-quark Production in Cosmic-Ray Proton Atmospheric Showers up to 1020eV
Authors: d’Enterria David , Pierog Tanguy , Sun Guanhao
Published: April 2019

Thepythia 6 Monte Carlo (MC) event generator, commonly used in collider physics, is interfaced for the first time with a fast transport simulation of a hydrogen atmosphere, with the same density as air, in order to study the properties of extended atmospheric showers (EAS) produced by cosmic-ray protons with energies–1020 eV. At variance with the hadronic MC generators (epos-lhc,qgsjet, andsibyll) commonly used in cosmic-ray physics,pythiaincludes the generation of harder hadronic jets and heavy (charm and bottom) quarks, thereby producing higher transverse momentum final particles, that could explain several anomalies observed in the data. The electromagnetic, hadronic, and muonic properties of EAS generated with various settings ofpythia 6, tuned to proton–proton data measured at the LHC, are compared to those fromepos-lhc,qgsjet 01,qgsjet-ii-04, andsibyll 2.1. Despite their different underlying parton dynamics, the characteristics of the EAS generated withpythia 6 are in between those predicted by the rest of the MC generators. The only exceptions are the muonic components at large transverse distances from the shower axis, wherepythiapredicts more activity than the rest of the models. Heavy-quark production, as implemented in this study for a hydrogen atmosphere, does not seem to play a key role in the EAS muon properties, pointing to nuclear effects as being responsible for the muon anomalies observed in the air-shower data.
Fullerene Oligomers and Polymers as Carriers of Unidentified IR Emission Bands
Authors: Krasnokutski S. A. , Gruenewald M. , Jäger C. , Otto F. , Forker R. , Fritz T. , Henning Th.
Published: April 2019

Several unidentified infrared emission bands (UIBs) have been assigned to neutral C60 molecules present in circumstellar and interstellar environments. However, due to the similarity of the infrared (IR) spectra of C60 in the solid state and in the gas phase, as of yet there is no consensus on the aggregation state of C60. In this article, we show that even strong covalent chemical bonding might have very little influence on the IR spectrum of C60, and that therefore such chemically bonded C60 could be the carrier of the same UIBs. It would best explain observations like the missing emission from C60 ions and a large variation of relative band intensities between different sources. We demonstrate that such a chemically bonded C60 can be produced by the co-condensation of C atoms together with C60 molecules, which leads to the formation of a three-dimensional C60 polymer film. Such polymerized C60 molecules cannot easily desorb, while their spectral properties in the visible and IR spectral ranges are almost undisturbed by polymerization.
Observation of a Reversal of Breakout Reconnection Preceding a Jet: Evidence of Oscillatory Magnetic Reconnection?
Authors: Hong Junchao , Yang Jiayan , Chen Huadong , Bi Yi , Yang Bo , Chen Hechao
Published: April 2019

Recent studies have revealed that solar jets involving minifilament eruptions may be initiated under the well-known magnetic-breakout mechanism. Before or just at the onset of those jets, there should be a current sheet, where breakout magnetic reconnection takes place, between open fields and the outside of the jet-base arcade carrying a minifilament in its core. In this paper we present a jet produced by the eruption of two minifilaments lying at the jet base. A current sheet is directly detected near the jet base before the onset of the eruption, suggesting the magnetic-breakout mechanism. However, we further find that the current sheet undergoes a transition. The current sheet first shortens to zero in length, but then lengthens toward an orthogonal direction relative to its initial orientation. The change of the current sheet gives rise to a reversal of the breakout reconnection, as the inflow and outflow regions before the transition become the outflow and inflow regions after the transition, respectively. We therefore propose that this observation provides evidence for the so-called oscillatory reconnection that is defined by a series of reconnection reversals but not yet proven to exist in the real plasma environment of the solar atmosphere.
Fire and windthrow in forests: Winners and losers in Neuropterida and Mecoptera
Authors: Duelli Peter , Wermelinger Beat , Moretti Marco , Obrist Martin К.
Published: April 2019

The mid-term impact of forest fires and windthrows on species compositions in the insect orders Neuroptera, Raphidioptera and Mecoptera was assessed in Swiss forests using standardized flight interception traps. For 50 species the abundances in intact control plots were compared to those in moderately or strongly disturbed forest stands. The catches were combined over four forest disturbance projects ranging from windthrows in alpine spruce forests and lowland deciduous forests to winter forest fires in Southern Switzerland and a large summer fire in southwestern Switzerland. As a result 82% of the 50 species benefited from the disturbance and became more abundant in the years after the fire or windthrow. More species (19) had their maximum abundance in intermediately disturbed plots than in heavily disturbed forests (17). Only 11 species mainly Hemerobiidae and Coniopterygidae peaked in the undisturbed forest stands. The species are listed per impact and ranked as winners (more than 66% specimens per treatment collected in disturbed forest plots) losers (more than 66% specimens per treatment in undisturbed forest plots) and indifferent species. An additional 29 species that were too scarce for an assessment are listed in Appendix 1. We conclude that for Neuropterida and Mecoptera catastrophic incidences are natural ecological events which create new habitats and by this foster their occurrence and abundance.
Living room conservation: a virtual way to engage participants in insect conservation
Authors: Clayborn Jaeson , Delamarre Alban
Published: April 2019

Through interactive gaming, virtual reality applied to butterfly and forest conservation activities can reach a broad audience and initiate a paradigm shift towards coexistence between humans and butterflies under urban settings. Butterfly World 1.0 is a serious game designed to teach players about butterflies and plants in dry forest ecosystems in the Florida Keys (USA). Tasks include butterfly and plant identification and the removal of an invasive ant species. The immersive virtual environment allows players to explore the forest without swarms of mosquitoes and oppressive heat present in the real environment. Rethinking a different way of communicating butterfly conservation and environmental stewardship through gaming, we can reach many who might otherwise remain untouched by traditional education routes. Virtual gaming, designed to educate the player through meaningful tasks and measurable outcomes, presents another avenue for direct knowledge acquisition and passive empathy through direct experiences.
L’accueil d’un enfant placé, un travail de réciprocité
Authors: Alecian Patrick
Published: April 2019

L’article démarre par un rappel de définition et d’exemples célèbres d’enfants exposés. Puis suit un rapide historique du placement en France avec l’institution du tour et les débuts de l’organisation étatique du placement. La deuxième partie traite d’un cas clinique complexe. Un jeune placé bébé dans une famille d’accueil est adopté par l’assistante familiale qui elle-même est une ancienne enfant placée devenue assistante sociale. L’enfant dès 4 ans se signale par des actes de violence sur les autres enfants en école maternelle et cela s’aggrave au fil des ans. Il est alors placé contrairement à l’avis de sa mère adoptive. Le suivi durera huit ans pendant lesquels l’auteur pense qu’il ne se passe pas grand-chose lors des entretiens plutôt monotones. Une magistrate va ensuite accéder à la demande de la famille et faire revenir l’enfant dans sa famille. Contrairement à toute attente des professionnels, cela s’avérera la bonne décision.
Problématique du père absent chez les adolescents confiés à la protection de l’enfance
Authors: Maheu Dominique
Published: April 2019

L’auteur commence par un rappel bref mais rigoureux de la fonction paternelle qui est toujours surprenante. Le père, en effet, peut ne pas être présent physiquement s’il l’est dans la parole de la mère comme le montrent les exemples de familles de pêcheurs ou la famille de René Char, le poète. Suit alors une vignette riche dans laquelle nous avons la narration du suivi d’un enfant dont la mère a toujours dit : « lui, il n’a pas de père » alors qu’en fait, il avait été reconnu par le père à la naissance mais celui-ci n’avait donné aucune suite à ce fait. L’histoire mouvementée de la marche de ce jeune vers son autonomie et la vie d’adulte constitue une démonstration de l’importance de la fonction paternelle.
Les petits riens d’un accueil familial
Authors: Krencker Antonella , Leydier Nicole , Lévy Noëlle
Published: April 2019

Blague, valises, petits riens du quotidien, attachement, généalogie, cette suite de mots à la Prévert constitue les titres de paragraphe d’un texte écrit par trois assistantes familiales qui tentent ainsi par des situations concrètes de nous faire partager la difficulté et le bonheur de faire ce métier si particulier.
Entre contraintes et prescription, l’accueil familial est en-jeu d’enfant
Authors: Martinez Anne-Marie
Published: April 2019

L’auteur nous fait partager sa riche expérience de responsable d’une grande institution de placement dans laquelle elle cherchera constamment à introduire la créativité, l’inventivité au sein des contraintes organisationnelles inévitables. Une première vignette nous révèle alors dans quel esprit peut se faire cette inventivité si nécessaire avec le petit Mamadou. Une deuxième vignette emmène le lecteur à constater comment l’injustice ressentie par une fille de 7 ans, Belle-Agnès, pourra être transformée en découverte merveilleuse de son univers mental par le moyen de dessins d’une très grande richesse. Et quand Belle-Agnès demandera dans un dessin, « à quel âge devient-on grand », ce sera au tour de l’auteur de constater avec humour que l’adulte manque parfois cruellement d’inventivité…
Penser et accepter ses propres mouvement pulsionnels en pouponnière
Authors: Aïdan Nathalie
Published: April 2019

« Je n’ai pas le droit de ressentir de l’amour pour eux, on nous l’a appris pendant notre formation », déclare une puéricultrice lors de séances de supervision dont rend compte l’auteur. Or, contrairement à cette injonction, Nathalie Aïdan défendra l’idée de pouvoir exprimer son ressenti devant chaque enfant afin de pouvoir vivre son métier de manière constructive en donnant toute l’attention qu’un bébé réclame pour lui. Une vignette clinique viendra illustrer cette proposition ainsi que tout l’intérêt que peuvent présenter les séances de supervision avec les personnels de pouponnières.
De la créativité au sein de l’institution : « La petite fabrique artistique »
Authors: Guého Corinne
Published: April 2019

Au départ, il y a l’idée de faire travailler les enfants placés individuellement dans une famille au sein d’un collectif et de réaliser ainsi une œuvre à la fois individuelle et dans un groupe. L’artiste, Corinne Guého, qui portera le projet avec Joëlle Delire, éducatrice de l’institution, déroule alors le processus qui a conduit au fil des années à constituer « La petite fabrique », un lieu et un ensemble de projets de création artistique autour de la céramique et de la poterie. L’enfant apprend les contraintes qui libèrent (la technique, les bons gestes, l’attention…), sa propre créativité et sa capacité à faire partager des idées, des réalisations concrètes et collectives avec d’autres enfants et avec les adultes.
L’entramès de Mestre Vicent: resplandor de la autoridad del predicador
Authors: Calvé Mascarell Óscar
Published: April 2019

El presente artículo aborda múltiples aspectos, algunos inéditos, referentes a l’entramès de Mestre Vicent. Entre los objetivos del estudio descuella la reconstrucción virtual y documentada de aquel carro que, quizá albergando la primera representación de Vicent Ferrer, desfiló en Valencia a finales de 1414 con ocasión de la entrada real de Fernando I. Otras cuestiones de especial relevancia atañen a la autoría del programa iconográfico y al proselitismo que denotaba aquella estructura, cuyos máximos beneficiarios fueron el Trastámara y la propia ciudad. Metodológicamente, se subraya la complejidad que entraña ceñir la interpretación del entremés amparada exclusivamente en la literatura, máxime cuando los otros vértices del triángulo de expresión medieval, oralidad y figuración, arrojan luz propia respecto al objeto de estudio.
La cultura visual en los sermones de San Vicente Ferrer y en los escenarios de su predicación
Authors: Español Bertran Francesca
Published: April 2019

En el estudio se analizan los sermones de san Vicente Ferrer desde la perspectiva de la historia del arte. Por un lado, los escenarios donde predicó y su adecuación espacial e iconográfica; por otro, rastreando en los sermones las alusiones a las técnicas arquitectónicas y artísticas y las referencias estéticas e iconográficas que contienen.
Vicent Ferrer, misionero apocalíptico. Sobre el uso de la pedagogía del terror en sus sermones medievales hispanos
Authors: Losada Carolina M.
Published: April 2019

El estudio del sentido de los sermones sobre el fin del mundo de Vicent Ferrer ha ocupado bastantes páginas en las últimas décadas. Su caso ha sido incluido en múltiples análisis sobre las ideas del Apocalipsis y el Anticristo en el período tardomedieval. Lo cierto es que su imagen –simbólica y pictórica– aparece usualmente ligada a su predicación del final a través de significantes visuales medievales del Apocalipsis. Eso no es casual; sin duda se debe a la intensidad de la predicación vicentina y a su énfasis en la pronta llegada del final de los tiempos.
Con la constante actualización de las estrategias para el estudio histórico de la predicación medieval se impone, sin embargo, una revisita a la predicación apocalíptica vicentina Este trabajo se propone abordar las estrategias específicas de la predicación del inminente final de los tiempos considerando las formas de persuasión sermonísticas como estrategias pedagógicas del terror. Es decir, detectar y analizar los elementos discursivos que pretenden un objetivo pastoral a través de la predicación de ideas que causan temor en quienes lo oyen. Esto sin abandonar la perspectiva de que la pedagogía no es una mera estrategia intencionada, sino que se ejerce en la voz de agente de comunicación social, formado en altas casas de estudio, con una trayectoria propia y en un contexto de producción específico.
Armes, armadures i batalles al·legòriques en els sermons de Vicent Ferrer
Authors: Ysern Josep
Published: April 2019

[ca] L’expressió de la lluita contra el pecat, del combat contra el dimoni constitueix una de les isotopies més generals i esteses en la predicació vicentina. Aquest estudi intenta, d’una banda, descriure l’aprofitament de l’al·legoria de les armes del cristià, d’arrel paulina, per a l’expressió de tal eix semàntic; d’altra, il·lustra, amb mostres preses de sermons vicentins, la utilització de metàfores i al·legories de base militar per a l’expressió del conflicte amb el mal. Finalment, s’atura en l’estudi de la batalla campal contra el dimoni, inclosa en un sermó de Quaresma, situant aquesta en el context d’altres utilitzacions del mateix tòpic.
L’esprit des droits
Authors: Ippolito Dario
Published: April 2019

« C’est de la bonté des lois criminelles que dépend principalement la liberté des citoyens. » Par sa critique des interdictions exorbitantes, des châtiments disproportionnés, des accusations invérifiables et des jugements arbitraires, Montesquieu nous apprend que le conflit entre individu et autorité n’est jamais plus dramatique et plus aigu que sur le terrain de la pénalité. Le pouvoir de punir est certes indispensable à la protection de nos droits, mais en les protégeant des violations qui les menacent, il menace lui aussi de les violer. Quelles limites assigner aux prohibitions légitimes ? Dans quel but et comment punir les transgresseurs ? Comment s’assurer de la violation des normes juridiques et de la responsabilité personnelle d’une action criminelle ? Envisagé dans la perspective de la philosophie du droit, L’Esprit des lois révèle sa puissante dimension normative et ouvre l’horizon du « garantisme pénal ».
Does Progressive Introduction of Benznidazole Reduce the Chance of Adverse Events in the Treatment of Chagas Disease?
Authors: Losada Galván Irene , Madrid Pascual Olaya , Herrero-Martínez Juan María , Pérez-Ayala Ana , Lizasoain Hernández Manuel
Published: April 2019

In this retrospective cohort study, we aimed to assess whether introducing benznidazole at escalating doses reduces the probability of adverse events or treatment discontinuation compared with a full-dose scheme. We collected data from patients who had chronic Trypanosoma cruzi infection and underwent treatment from July 2008 to January 2017 in a referral center in Madrid. Dose was adjusted to body weight (5 mg/kg/day), with treatment introduction with full dose or escalating dose according to local consensus and protocols. Among the 62 patients treated, benznidazole was introduced at full dose in 28 patients and on escalating dose in the remaining 34. We found no statistical differences in the number of adverse events, treatment discontinuations, days of treatment, or sociodemographic profiles. There is insufficient evidence to support escalating dose as a strategy for reducing the adverse effects of benznidazole. Further research is needed to evaluate this approach.
Testing the Competence of Cimex lectularius Bed Bugs for the Transmission of Borrelia recurrentis, the Agent of Relapsing Fever
Authors: El Hamzaoui Basma , Laroche Maureen , Bechah Yassina , Bérenger Jean Michel , Parola Philippe
Published: April 2019

In recent years, bed bugs have reappeared in greater numbers, more frequently, and are biting humans in many new geographic areas. Infestations by these hematophagous insects are rapidly increasing worldwide. Borrelia recurrentis, a spirochete bacterium, is the etiologic agent of louse-borne relapsing fever. The known vectors are body lice, Pediculus humanus humanus. However, previous studies have suggested that bed bugs might also be able to transmit this bacterium. Adult Cimex lectularius were artificially infected with a blood meal mixed with bacterial suspension of B. recurrentis. They were subsequently fed with pathogen-free human blood until the end of the experiment. Bed bugs and feces were collected every 5 days to evaluate the capacity of bed bugs to acquire and excrete viable B. recurrentis using molecular biology, cultures, fluorescein diacetate and immunofluorescence assays. The feces collected on the day 5 and 10 postinfection contained viable bacteria. Immunofluorescence analysis of exposed bed bugs showed the presence of B. recurrentis in the digestive tract, even in bed bugs collected on day 20 after infection. Like human body lice, bed bugs can acquire, maintain, and excrete viable B. recurrentis that might infect humans through skin lesions. This preliminary work suggests that bed bugs might be competent vectors of B. recurrentis. Because bed bugs and body lice may share the same ecological niches, the role of bed bugs in transmitting recurrent fevers deserves further study.
Seroprevalence of Hepatitis B, Hepatitis C, and Human T-Cell Lymphotropic Virus Infections in HIV-Infected Patients in Sierra Leone
Authors: Yendewa George A. , Sahr Foday , Aguilera Antonio , Lakoh Sulaiman , Sesay Momodu , Deen Gibrilla F. , Patiño Lucia , Poveda Eva , Salata Robert A.
Published: April 2019

HIV coinfection with hepatitis B virus (HBV), hepatitis C virus (HCV), and human T-cell lymphotropic viruses 1 and 2 (HTLV-1 and HTLV-2) is common because of shared transmission routes. There is no published data on the prevalence of these infections in people living with HIV in Sierra Leone. We conducted a cross-sectional study of 211 HIV-positive patients aged ≥ 18 years in Freetown, Sierra Leone, in November 2017. Plasma samples were analyzed using the chemiluminescent microparticle immunoassay (Architect System, Abbott ARCHITECT Analyzer, Abbott Park, IL. The majority were female (63.5%), with median age 36 years (interquartile range [IQR]: 32–44) and median CD4 count of 396 cells/µL (IQR: 214–534). Sixty patients (28.4%) were newly diagnosed and antiretroviral therapy (ART) naive; 151 patients (71.6%) were ART experienced. The prevalence of the hepatitis B surface antigen (HBsAg), total anti-hepatitis B core antibody, and anti-HCV was 21.7%, 82.9%, and 4.3%, respectively. No cases of HTLV-1 or HTLV-2 were detected. Male gender (P = 0.004) and CD4 < 350 cells/µL (P = 0.017) were associated with the HBsAg positive status.
CFD Simulation of Oil Jets for Piston Cooling Applications Comparing the Level Set and the Volume of Fluid Method
Authors: Wendling Loic , Behr Marek , Hopf Anselm , Kraemer Frank , Weber Carsten , Turner Paul
Published: April 2019

A new CFD simulation model and methodology for oil jet piston cooling has been developed using the modern level set approach. In contrast to the widely used volume of fluid (VOF) method, the level set approach explicitly tracks the interface surface between oil and air, using an additional field equation. The method has been extensively tested on two- and three-dimensional examples using results from literature for comparison. Furthermore, several applications of oil jet piston cooling on Ford engines have been investigated and demonstrated. For example, three-dimensional simulations of piston cooling nozzle jets on a diesel engine have been calculated and compared to test-rig measurements. Laminar jets, as well as jets with droplets and fully atomized jets, have been simulated using realistic material properties, surface tension, and gravity. Simulations of cooling jets on the undercrown of a gasoline piston and on a moving piston with a cooling gallery have been investigated and compared to test-rig measurements. Results of a VOF model with the CFD software STAR-CCM+ used in the Ford CAE workflow have been compared to the new level set method. Despite using different computational approaches (level set versus volume of fluid method), the results are similar for laminar jets. Differences occur for semi-turbulent and atomized oil jets with many droplets, which need highly resolved meshes. All in all, the modern CFD tools are a powerful way for investigating active cooling strategies for pistons in order to improve the efficiency of internal combustion engines and to reduce emissions.
Automotive Waste Heat Recovery after Engine Shutoff in Parking Lots
Authors: Syed Zaker , Wagner John R.
Published: April 2019

1
The efficiency of internal combustion engines remains a research challenge given the mechanical friction and thermodynamic losses. Although incremental engine design changes continue to emerge, the harvesting of waste heat represents an immediate opportunity to address improved energy utilization. An external mobile thermal recovery system for gasoline and diesel engines is proposed for use in parking lots based on phase change material cartridges. Heat is extracted via a retrofitted conduction plate beneath the engine block after engine shutoff. An autonomous robot attaches the cartridge to the plate and transfers the heat from the block to the Phase Change Material (PCM) and returns later to retrieve the packet. These reusable cartridges are then driven to a Heat Extraction and Recycling Tower (HEART) facility where a heat exchanger harvests the thermal energy stored in the cartridges. A series of mathematical models are created to estimate the recoverable heat from a standard parking lot configuration. A representative case study that considered 500 cars with periodic traffic flow over a period of 16 hours can heat approximately 25 kiloliters of potable water from 15°C to 50°C. Future development will involve the creation of strategies to extract heat during engine idling at traffic stops and drive through lanes.
Sensitivity Analysis and Control Methodology for Linear Engine Alternator
Authors: Bade Mehar , Clark Nigel , Famouri Parviz , Guggilapu PriyaankaDevi , Darzi Mahdi , Johnson Derek
Published: April 2019

Linear engine alternator (LEA) design optimization traditionally has been difficult because each independent variable alters the motion with respect to time, and therefore alters the engine and alternator response to other governing variables. An analogy is drawn to a conventional engine with a very light flywheel, where the rotational speed effectively is not constant. However, when springs are used in conjunction with an LEA, the motion becomes more consistent and more sinusoidal with increasing spring stiffness. This avoids some attractive features, such as variable compression ratio HCCI operation, but aids in reducing cycle-to-cycle variation for conventional combustion modes. To understand the cycle-to-cycle variations, we have developed a comprehensive model of an LEA with a 1kW target power in MATLAB®/Simulink, and an LEA corresponding to that model has been operated in the laboratory. This MATLAB®/Simulink numerical model has been used to examine the sensitivity of the LEA dynamics and performance parameters to changes in the design and operating inputs. The sensitivity analysis provides insight into the pathway for improving and optimizing the design, as well as an assessment of the effects of modeling assumptions on the reliability of predictions. A difficulty during the modeling is associated with the cycle-to-cycle energy balance for the LEA, and it is clear that this difficulty is reflected in real-world LEA control. If the alternator consumes more energy in a cycle than the engine provides, the system moves towards a stall. If the alternator consumes less energy, then the stroke, compression ratio and maximum translator velocity must rise steadily from cycle-to-cycle until efficiency losses curb the increase. The authors have recognized that the control of this energy balance in the model affects sensitivity analysis and must, therefore, mimic the real world intended control methodology. To understand the LEA behavior further, a control methodology was developed based on the basic feedback control systems in order to monitor the compression ratio of the single cylinder LEA system from cycle-to-cycle, with a view of keeping compression ratio substantially constant. Initially, the LEA system behavior was analyzed with and without the external controller, mainly to highlight the importance and need for an external control methodology. Further, two different control strategies were implemented and investigated. Finally, the cycle-to-cycle variations were studied as spring stiffness increased, by introducing combustion stochastics. With the proposed controller strategies and the addition of stiff springs, the cycle-to-cycle variations were reduced, and the LEA system operated steadily.
Durability Study of a High Pressure Common Rail Fuel Injection System Using Lubricity Additive Dosed Gasoline-Like Fuel - Additional Cycle Runtime and Teardown Analysis
Authors: Tzanetakis Tom , Traver Michael , Costanzo Vincent , Medina Roberto , Nelson John , Matusik Katarzyna , Sforzo Brandon , Kastengren Alan , Powell Christopher
Published: April 2019

This study is a continuation of previous work assessing the robustness of a Cummins XPI common rail injection system operating with gasoline-like fuel. All the hardware from the original study was retained except for the high pressure pump head and check valves which were replaced due to cavitation damage. An additional 400 hour NATO cycle was run on the refurbished fuel system to achieve a total exposure time of 800 hours and detect any other significant failure modes. As in the initial investigation, fuel system parameters including pressures, temperatures and flow rates were logged on a test bench to monitor performance over time. Fuel and lubricant samples were taken every 50 hours to assess fuel consistency, metallic wear, and interaction between fuel and oil. High fidelity driving torque and flow measurements were made to compare overall system performance when operating with both diesel and light distillate fuel. Injector rate shapes were measured as a function of time, and high resolution x-ray imaging of the nozzle tips was performed as part of the final teardown analysis. At the end of testing, there was a loss of rail pressure control at low fueling rates due to cavitation of the pump inlet check valve, consistent with prior findings. Excessive fuel-in-oil dilution was not observed under normal operating conditions, and there was no indication of significant fuel contamination by oil as evidenced by elemental analysis. The gasoline-like fuel required higher fuel system driving power and had a lower hydraulic efficiency than diesel due to a combination of higher vapor formation and leakage flow. Injectors exhibited reduced fueling rates after 600 hours of exposure and showed significant signs of cavitation damage within the nozzle tip. However, fuel wetted components in sliding contact did not show extraordinary signs of wear, potentially due to the use of lubricity additive.
Influence of Turbulence and Thermophysical Fluid Properties on Cavitation Erosion Predictions in Channel Flow Geometries
Authors: Magnotti Gina M. , Battistoni Michele , Saha Kaushik , Som Sibendu
Published: April 2019

Cavitation and cavitation-induced erosion have been observed in fuel injectors in regions of high acceleration and low pressure. Although these phenomena can have a large influence on the performance and lifetime of injector hardware, questions still remain on how these physics should be accurately and efficiently represented within a computational fluid dynamics model. While several studies have focused on the validation of cavitation predictions within canonical and realistic injector geometries, it is not well documented what influence the numerical and physical parameters selected to represent turbulence and phase change will have on the predictions for cavitation erosion propensity and severity.

In this work, a range of numerical and physical parameters are evaluated within the mixture modeling approach in CONVERGE to understand their influence on predictions of cavitation, condensation and erosion. Particular attention is paid to grid resolution, turbulence model and near-wall treatment, fuel surrogate properties, and non-condensable gas content. Assessment of cavitation predictions are conducted through comparison of measured and predicted mass flow rates and cavitation probability distributions for flow through a channel with a sharp inlet. Predictions for hydrodynamic impact loading and cavitation erosion are compared with the experimentally measured incubation period and critical site for erosion. Based on these findings, recommendations are provided for modeling turbulent cavitating flows, using the single fluid mixture modeling approach, to improve predictions for cavitation-induced erosion. In particular, to capture the fluid dynamic phenomena characterizing cavitation cloud formation, development and shedding, a Large Eddy simulation with grid resolution as fine as 2.50 μm is recommended. The assumed concentration of non-condensable gas content is observed to have a strong influence on the predicted cavitation erosion severity, which motivates the need for dissolved gas concentration measurements for future cavitation erosion experimental studies. Using the best practices established in this work, good agreement is achieved between the measured and predicted cavitation parameters, as well as the critical site for cavitation-induced erosion.
Review of Vehicle Engine Efficiency and Emissions
Authors: Joshi Ameya
Published: April 2019

This review paper covers major regulatory and technology developments in 2018 pertinent to tailpipe emissions of greenhouse gases and criteria pollutants. Europe has proposed ambitious reductions in CO2 limits for both light- and heavy-duty sectors. The challenge is compounded with changing measurement norms and a significant shift away from fuel efficient diesels in the light-duty (LD) space. Both incremental and step changes are being made to advance internal combustion. New studies show that in-use NOx emissions from diesels can be much lower than required by the Euro 6 regulation. Discussions have already started on Euro 7 regulations, and the leading regulatory concepts and proposed technical solutions are provided.

In the heavy-duty (HD) sector, the progress is outlined in improving engine and vehicle fuel efficiency through the US Department of Energy’s (DOE’s) SuperTruck II program and other representative studies. Common approaches among the participants include hybridization, waste heat recovery, and both open- and closed cycle incremental improvements. Emissions control focus is on evaluating pathways to achieve California’s contemplated low-NOx standards, recently also supported by the US EPA through the Cleaner Trucks Initiative. The challenge is to reduce cold start and low load emissions, requiring innovative engine and after-treatment system solutions. Leading concepts include close-coupled SCR (selective catalytic reduction), use of passive NOx adsorbers, integration of SCR (selective catalytic reduction) on DPFs (diesel particulate filters), low temperature urea or ammonia injection, dual SCR, and active and passive thermal management to raise exhaust temperatures. Work is also underway on a new low load certification cycle.

Continued advancement is made on after-treatment components. Aged three-way catalysts (TWCs) and diesel oxidation catalysts (DOCs) are nearing 90% conversion at 150 °C. SCR catalysts continue to improve both their low temperature conversion as well as high temperature durability. Particulate regulations in Europe, China and India are leading to widespread adoption of gasoline particulate filters (GPFs). Lean burn gasoline engines can offer significant fuel economy benefits. NOx control is a challenge, and passive SCR systems and new catalysts are proposed.
A Method for Identifying Most Significant Vehicle Parameters for Controller Performance of Autonomous Driving Functions
Authors: Korus Jan-Dominik , Bullinger Markus , Schuetz Christoph , Garcia Ramos Pilar , Wagner Sebastian , Müller Steffen
Published: April 2019

In this paper a method for the identification of most significant vehicle parameters influencing the behavior of a lateral control system of autonomous car is presented. Requirements for the design stage of the controller need to consider many uncertainties in the plant. While most vehicle properties can be compensated by an appropriate tuning of the control parameters, other vehicle properties can change significantly during usage. The control system is evaluated based on performance measures. Analyzed parameters comprise functional tire characteristics, mass of the vehicle and position of its center of gravity. Since the parameters are correlated, but Sobol’ sensitivity analysis assumes decorrelated inputs, random variation yields no reasonable results. Furthermore, the variation of each parameter or set of parameters is not applicable since the numbers of required simulations is increased significantly according to input dimension. Therefore, the proposed methodology determines directly the influence of the parameters on performance measures of the lateral control function. First, a hierarchical nonlinear principal component analysis using artificial neural networks is used to decouple inputs and reduce them to a lower dimensional subspace. In a second step Sobol’ sensitivity analysis is used to identify the significant parameters by sampling in the decoupled subspace and their evaluation by a full-blown vehicle dynamics simulation. The most significant parameters are merged in a static and dynamic variable resulting in four worst-case vehicle states. Applying the methodology of the Cooperative Design Approach, performance measures of the lateral control function (rising time, overshoot, number of oscillations) can be analyzed for each vehicle state yielding a robust control design.
Dilution and Injection Pressure Effects on Ignition and Onset of Soot at Threshold-Sooting Conditions by Simultaneous PAH-PLIF and Soot-PLII Imaging in a Heavy Duty Optical Diesel Engine
Authors: Li Zheming , Roberts Gregory , Musculus Mark
Published: April 2019

Although accumulated in-cylinder soot can be measured by various optical techniques, discerning soot formation rates from oxidation rates is more difficult. Various optical measurements have pointed toward ways to affect in-cylinder soot oxidation, but evidence of effects of operational variables on soot formation is less plentiful. The formation of soot and its precursors, including polycyclic aromatic hydrocarbons (PAHs), are strongly dependent on temperature, so factors affecting soot formation may be more evident at low-temperature combustion conditions. Here, in-cylinder PAHs are imaged by planar laser-induced fluorescence (PAH-PLIF) using three different excitation wavelengths of 355, 532, and 633 nm, to probe three different size-classes of PAH from 2-3 to 10+ rings. Simultaneous planar laser-induced incandescence of soot (soot-PLII) using 1064-nm excitation provides complementary imaging of soot formation near inception. To achieve low combustion temperatures at the threshold of PAH and soot formation, the engine operating conditions are highly diluted, with intake-O2 mole-fractions as low as 7.5%. The optical diagnostics show that increasing dilution delays the inception of PAH by over 2.5 ms as the intake-O2 mole-fraction decreases from 15.0% to 9.0%. At 7.5% intake-O2, no large PAH or soot are formed, while the 9.0% intake-O2 condition forms PAH but virtually no detectable soot. Conditions with 10.0% or more intake-O2 form both PAH and soot. For the threshold-sooting condition with 10.0% intake-O2, large PAH typically forms broadly throughout the cross-section of the downstream jets and along the bowl-wall. Soot appears after PAH, and in narrower ribbons in the jet-jet interaction region. These soot ribbons are on the periphery of the PAH, near the diffusion flame, where the highest temperatures are expected. With increasing intake-O2, the delay time between soot and PAH shortens, and soot tends to shift upstream to the jet region prior to wall impingement, though still on the periphery of the PAH. The spatial distributions of PAH and soot overlap slightly under these threshold-sooting conditions, with soot typically surrounding the PAH. This may indicate that temperatures are only high enough for soot formation on the jet periphery, near the diffusion flame. The minimal overlap also suggests that PAHs are rapidly consumed and/or adsorbed when soot is formed. Additionally, increasing the fuel-injection pressure from 533 to 800 and then to 1200 bar increases soot and large PAH formation, which is opposite to the trend for conventional diesel combustion.
Modeling of Oil Transport between Piston Skirt and Cylinder Liner in Internal Combustion Engines
Authors: Meng Zhen , Ahling Sebastian , Tian Tian
Published: April 2019

The distribution of lubricating oil plays a critical role in determining the friction between piston skirt and cylinder liner, which is one of the major contributors to the total friction loss in internal combustion engines. In this work, based upon the experimental observation an existing model for the piston secondary motion and skirt lubrication was improved with a physics-based model describing the oil film separation from full film to partial film. Then the model was applied to a modern turbo-charged SI engine. The piston-skirt FMEP predicted by the model decreased with larger installation clearance, which was also observed from the measurements using IMEP method at the rated. It was found that the main period of the cycle exhibiting friction reduction is in the expansion stroke when the skirt only contacts the thrust side for all tested installation clearances. The main reason for lower skirt friction with larger clearance is greater amount of oil available during the expansion stroke.
Development of Motor with Heavy Rare Earth-Free Magnet for Two-Motor Hybrid System
Authors: Ito Yuta , Aoki Tadanobu , Naito Tomokazu , Hiranishi Toru
Published: April 2019

Conventional HEV motors use neodymium magnets with added heavy rare earths, to realize high output and size reduction. However, deposits of heavy rare earths such as Dysprosium (Dy) and Terbium (Tb) are unevenly distributed, so it is important to reduce the amount used, because of supply issue and material cost. In this paper, the application of a heavy rare earth-free magnet is considered on the new motor for a two-motor hybrid system. Compared to conventional neodymium magnets, heavy rare earth free magnets tend to have low coercivity. Also, heavy rare earth-free magnet have low thermal durability, so it is not easy to apply them to motors for a two-motor hybrid system, which requires high output and small size. The motor requires twice as much torque and six times output than one-motor hybrid system. Increase demagnetization resistance and magnet cooling performance is studied by development of the new motor. With the new rotor structure, a magnetic circuit suitable for the magnetic property of heavy rare earth-free magnet was designed, and demagnetization resistance property is raised 24%. Also, the new motor cooling system is a shaft cooling structure, which uses centrifugal force to supply refrigerant to the interior of the rotor yoke, achieving a 23% increase in magnet cooling performance. This technology succeeded in applying heavy rare earth-free magnet to the motor for a two-motor hybrid system, while maintaining high power density.
An Investigation of the Influence of Close-Proximity Traffic on the
Aerodynamic Drag Experienced by Tractor-Trailer Combinations
Authors: McAuliffe Brian , Ahmadi-Baloutaki Mojtaba
Published: April 2019

Recent research to investigate the aerodynamic-drag reduction associated with
truck platooning systems has begun to reveal that surrounding traffic has a
measurable impact on the aerodynamic performance of heavy trucks. A 1/15-scale
wind-tunnel study was undertaken to measure changes to the aerodynamic drag
experienced by heavy trucks in the presence of upstream traffic. The results,
which are based on traffic conditions with up to 5 surrounding vehicles in a
2-lane configuration and consisting of 3 vehicle shapes (compact sedans, SUVs,
and a medium-duty truck), show drag reductions of 1% to 16% for the heavy truck
model, with the largest reductions of the same order as those experienced in a
truck-platooning scenario. The data also reveal that the performance of
drag-reduction technologies applied to the heavy-truck model (trailer
side-skirts and a boat-tail) demonstrate different performance when applied to
an isolated vehicle than to conditions with surrounding traffic. The results
suggest that vehicle shape optimization strategies may differ if the influence
of wake effects from surrounding traffic is included in product development
cycles. Additionally, truck-platooning benefits should be taken in the context
of typical traffic scenarios for which trucks are already experiencing a
background-platooning effect and therefore may not be expected to attain the
benefits relative to isolate-vehicle conditions.
Material and Damage Models of Randomly-Oriented Thermoplastic Composites for Crash Simulation
Authors: Hayashi Seiji , Kan Mitsuharu , Saito Kei , Nishi Masato
Published: April 2019

This study developed a material model with a damage function that supports finite element analyses in crash strength analyses of beams manufactured using randomly-oriented long fiber thermoplastics composites. These materials are composites with randomly-oriented carbon tow having a fiber length of approximately one inch, and are isotropic in-plane from a macro perspective, but exhibit different damage properties for tension and compression. In the out-of-plane direction, the influence of the resin matrix properties increases, and the materials properties are similar to those of laminate materials. This means they are anisotropic materials with physical properties that differ from those in the in-plane direction. In order to verify the influence of these characteristics, the damage process was observed by three-point bending of a flat plate, which is a mixed mode that includes tension, compression, and out-of-plane shear. Digital image correlation was used to analyze the strain distribution in the edgewise direction, and the results showed that damage progresses from the surface toward the inside of the plate. A damage model was created that takes this phenomenon into account. This damage model uses a format that organizes the difference between the in-plane tension and compression damage properties in terms of the triaxial stress level, and accumulates damage according to each stress level. This model also separately accumulates the out-of-plane shear damage, and associates it with the in-plane compression damage. The accuracy of the developed material model was verified by comparison with three-point bending tests of closed-hat-section beams. The verification results showed a close approximation in terms of the load- stroke profiles and fracture format. This indicates that a material model that takes into account in-plane and out-of-plane damage can accurately express macro bending behavior.
Color and Height Characteristics of Surrogate Grass for the Evaluation of Vehicle Road Departure Mitigation Systems
Authors: Yi Qiang , Shen Dan , Lin Jun , Chien Stanley , Li Lingxi , Chen Yaobin , Sherony Rini
Published: April 2019

In recent years Road Departure Mitigation Systems (RDMS) is introduced to the market for avoiding roadway departure collisions. To support the performance testing of the RDMS, the most commonly seen road edge, grass, is studied in this paper for the development of standard surrogate grass. This paper proposes a method for defining the resembling grass color and height features due to significant variations of grass appearances in different seasons, temperatures and environments. Randomly selected Google Street View images with grass road edges are gathered and analyzed. Image processing techniques are deployed to obtain the grass color distributions. The height of the grass is determined by referencing the gathered images with measured grass heights. The representative colors and heights of grass are derived as the specifications of surrogate grass for the standard evaluation of RDMS.