bluuebunny/crossref_metadata_2025 huggingface dataset:
Dynamic factors associated with COVID-19 vaccine uptake in Cameroon between 2021 and 2022
Authors: Tchiasso Dora , Mendjime Patricia , Njuwa Fai Karl , Nana Wandji Brenda S. , Yuya Francis , Youm Éric , Stanton Amelia M. , Karimu Ismaila , Bebell Lisa M. , Matchim Lucrece , Buri Bongkiyung D. , Ntone Rodrigue , Yonta Cyrille , Tchame Claudric R. , Essaka Rachelle , Eyong Justin B. , Ngosso Audrey , Nanda Herwin , Nsaibirni Robert , Ndifon Mark , Eteki Lucrèce , Mandeng Nadia , Zoung-Kani Bisseck Anne-Cécile , Koku Modeste T. , Epée Emilienne , Etoundi Mballa Georges-Alain , Tchocfe Ndoula Shalom , Esso Linda , Boum II Yap
Published: November 2024

Background: Little is known about attitudes towards COVID-19 vaccination in sub-Saharan Africa, where immunisation coverage is the lowest in the world.Aim: The study aimed to identify factors associated with COVID-19 vaccine hesitancy and uptake in Cameroon, and assess changes in these factors over a period of time.Setting: The study was conducted in the ten regions of Cameroon.Methods: The authors conducted a two-phase cross-sectional survey in the 10 regions of Cameroon, from July 2021 to August 2021 (Phase one) and from August 2022 to September 2022 (Phase two). We analysed reasons for vaccine hesitancy descriptively and used logistic regression to assess factors associated with hesitancy.Results: Overall, we enrolled 12 109 participants: 6567 (54.23%) in Phase one and 5542 (45.77%) in Phase two. Of these, 8009 (66.14%) were not interested in receiving the COVID-19 vaccine (n = 4176 in Phase one, n = 3833 in Phase two). The refusal rate increased significantly in the northern region from 27.00% in Phase 1 to 60.00% in Phase two. The leading contributor to COVID-19 vaccine hesitancy was fear that the vaccine was dangerous, which was significantly associated (95% confidence interval [CI], p  0.05%) with vaccine refusal in both phases. Overall, 32.90% of participants (n = 2578) perceived the COVID-19 vaccine to be dangerous. Advanced age, male gender, Muslim religion and low level of education were associated with vaccine acceptance. Participants reported that healthcare workers were the most trusted source of information about the COVID-19 vaccine by 5005 (42.84%) participants.Conclusion: Despite the investment of the Ministry of Health and its partners in community engagement, focussing on communication about the vaccine efficacy, tolerance and potential adverse events, fear of the vaccine remains high, likely leading to vaccine hesitancy in Cameroon between 2021 and 2022.Contribution: The study highlight regional variations in COVID-19 vaccine acceptance in Cameroon, with factors age, gender, religion and education influencing willingness to vaccine. Trust in health workers was high, indicating that, tailored, community-led vaccination strategies are key for improving vaccine uptake, not only for COVID-19 but also for future epidemics.
Combined Laparoscopic Cholecystectomy and Transcystic Common Bile Duct Exploration for Choledocholithiasis
Authors: El-Dawy Wael A.
Published: November 2024

Background:

There is no consensus on the ideal approach for managing patients with common bile duct (CBD) stones. The combined approach is less popular, possibly due to the complexity of the surgical technique and the availability of choledochoscope.

Aim:

We aim to assess the safety and feasibility of transcystic (TC) CBD exploration using the flexible bronchoscope for choledocholithiasis.

Methods:

Forty patients with symptomatic calculus gallbladder with concomitant CBD stones were randomized into two groups. Single-session laparoscopic cholecystectomy (LC) and laparoscopic TC CBD exploration were performed for one group using the flexible bronchoscope. Endoscopic retrograde cholangiopancreatography followed by LC after 4–6 weeks was conducted for the other group.

Results:

Twenty patients were randomized to each group. The clearance rate of CBD stones was significantly higher in the single-session Group A (95%) than in the two-session Group B (70%). Group B was associated with a significantly prolonged operative (P = 0.01). The total hospital stay and operative time were significantly longer in Group B than in Group A (P = 0.004). There was no significant difference between both groups regarding the intraoperative or postoperative complications.

Conclusion:

Combined LC and TC CBD exploration is a safe and feasible approach and is associated with significantly shorter operative time and length of hospital stay.
Transformer Based Ship Detector: An Improvement on Feature Map and Tiny Training Set
Authors: Ngo Duc-Dat , Vo Van-Linh , My-Ha Le  , Hoc-Phan  , Nguyen Manh Hung
Published: November 2024

The exponential increment of commodity exchange has raised the need for maritime border security in recent years. One of the most critical tasks for naval border security is ship detection inside and outside the territorial sea. Conventionally, the task requires a substantial human workload. Fortunately, with the rapid growth of the digital camera and deep-learning technique, computer programs can handle object detection tasks well enough to replace human labor. Therefore, this paper studies how to apply recent state-of-the-art deep-learning networks to the ship detection task. We found that with a suitable number of object queries, the Deformable-DETR method will improve the performance compared to the state-of-the-art ship detector. Moreover, comprehensive experiments on different scale datasets prove that the technique can significantly improve the results when the training sample is limited. Last but not least, feature maps given by the method will focus well on key objects in the image.
EL APRENDIZAJE ACTIVO DE LA SIMULACIÓN EDUCATIVA PARA EL ALUMNADO DE SECUNDARIA EN EDUCACIÓN CÍVICA
Authors: BARRIGA ELVIRA , WILSON-DAILY ANN ELIZABETH
Published: November 2024

En el presente artículo se examinan las prácticas de aprendizaje activo más usuales para la enseñanza de la materia en ciencia política. Concretamente se destaca el método de la simulación como práctica didáctica que tiene el potencial de mejorar el proceso de enseñanza-aprendizaje del estudiantado y aprender mediante la experiencia personal. Las autoras defienden la creación de programas educativos que incluyan actividades de simulación o simulacro de procedimientos relacionados con la política, basándose en los resultados de investigaciones preliminares. Estas investigaciones apuntan que con la simulación de experiencias sociopolíticas el estudiantado que participa en ellas adquiere un aprendizaje relevante de conocimientos, habilidades y valores que pueden favorecer una participación más activa de los participantes de cara al futuro. Se destaca la necesidad de realizar más estudios de carácter empírico sobre la aplicación de este tipo de simulaciones.
Presentación
Authors: Vásquez Gabriela
Published: November 2024

Presentación de la revista.
LOS RETOS Y LAS OPORTUNIDADES EN LA COMPRENSIÓN DEL TIEMPO HISTÓRICO: UN EJEMPLO DE INVESTIGACIÓN-ACCIÓN EN LA ENSEÑANZA SECUNDARIA
Authors: Llusá Serra Joan
Published: November 2024

El presente artículo pone de relevancia por un lado, la importancia de la investigación y acción del docente para la mejora de su propia praxis y, por otor lado, la necesidad de aplicar en el proceso de esenñanza y aprendizaje de la Historia un trabajo específico sobre el tiempo histórico y sus principales operadores...
OTRAS PUBLICACIONES DE ENSEÑANZA EN LA HISTORIA
Authors: Andamio Equipo
Published: November 2024

OTRAS PUBLICACIONES DE ENSEÑANZA EN LA HISTORIA
Indice
Authors: Equipo Andamio
Published: November 2024

Contenido de la revista.
INNOVACIÓN EN LA ENSEÑANZA UNIVERSITARIA. LAS PRÁCTICAS DE LOS FUTUROS PROFESORES DE HISTORIA
Authors: Coudannes Aguirre Mariela Alejandra , Andelique Servan Carlos Marcelo
Published: November 2024

En Santa Fe, Argentina, los estudiantes de Historia deben realizar prácticas docentes universitarias. Se espera que construyan y desarrollen propuestas de enseñanza que sean alternativas a las clases magistrales que suelen predominar en este nivel.Para saber si eso se logra, se investigaron las planiﬁcaciones, actividades, materiales y reﬂexiones producidas por los practicantes y las observaciones realizadas por los profesores coordinadores. Desde una perspectiva crítica, se buscó comprender el sentido de las mismas, reconocer los aspectos metodológicos más relevantes que le otorgan un carácter innovador, los supuestos que las sustentan, entre otros aspectos.Más allá de algunas continuidades con las rutinas instituidas, el for-mato de las clases de los practicantes logra romper con concepciones tradicionales de enseñanza centradas en la exposición del profesor a partir de la utilización de diferentes estrategias y recursos.
VII SIMPOSIO INTERNACIONAL DE DIDÁCTICA DE LAS CIENCIAS SOCIALES EN EL ÁMBITO IBEROAMERICANO
Authors: Andamio Equipo
Published: November 2024

Como en anteriores encuentros, este simposio sobre la didác-tica de las Ciencias Sociales en el ámbito Iberoamericano tiene como ﬁnalidad el intercambio de experiencias, la puesta en común de las acciones e investigaciones que se desarrollan en este ámbito desde los distintos puntos de la geografía internacional. Un espacio de reﬂexión para especialistas, docentes e instituciones que colaboran con esta línea de trabajo.
NORMAS DE PUBLICACIÓN DE LA REVISTA
Authors: Andamio Equipo
Published: November 2024

ESTRUCTURA DEL TEXTO DE ARTÍCULOSEstas referencias se señalan para los siguientes apartados: La Mirada del Experto, Investigaciones en Didáctica de la Historia y Otras investigacio-nes en Didáctica de la Historia y las Ciencias Sociales.
¿QUÉ ENTENDEMOS POR PATRIMONIO? CONCEPTUALIZACIONES DE LOS AGENTES EDUCATIVOS Y DE LOS ESTUDIANTES DE LA CIUDAD DE VALPARAÍSO.
Authors: Collao Donoso Dámaris
Published: November 2024

La investigación que se presenta tiene por objetivo “Reconocer la concepción que los distintos actores del proceso de enseñanza aprendizaje (profesores, directores de escuelas, gestor cultural, encargado del consejo de cultura) poseen sobre lo que es el patrimonio y sus características”. Todo esto con el fin de establecer un diagnóstico sobre las concepciones de los distintos actores del proceso de enseñanza- aprendizaje y determinar de esta forma si existe ambigüedad, diversidad o carencia de profundidad en ella, con el fin de reconocer el estado de la enseñanza del patrimonio en la ciudad y así plantear mejoras. Desde una perspectiva metodológica, se escogió la utilización del método mixto de investigación, con una muestra no probabilística intencionada de 450 estudiantes de segundo ciclo de educación básica de la ciudad de Valparaíso, distribuidos en la tipología de dependencia que posee el país, más 6 entrevistas a profesores y 6 a directores de colegio. En términos generales los datos recopilados apuntan a que los discursos de los docentes y directores de escuelas transitan en asignar al Patrimonio un valor identitario y de herencia, y por su parte, los gestores culturales (encargado de Consejo de Cultura y encargado de Museo) tienen una visión holística ligada a la multidimensionalidad presente en el concepto. La diversidad en cuanto a la profundidad y descripción conceptual de los agentes educativos influye de forma directa en las concepciones de los estudiantes de la ciudad.
ENSEÑANZA DE PUEBLOS ORIGINARIOS DE CHILE CENTRAL: PROMAUCAES, OMISIÓN EN LA EDUCACIÓN, DEUDA CON EL PATRIMONIO
Authors: Olave Pozo Alejandra
Published: November 2024

Desde la mirada educativa se evidencia una omisión y deu-da con los pueblos originarios de Chile central, especialmente con el grupo conocido como Promaucaes, habitantes ancestrales cuya ense-ñanza no se replica en la formación de los niños y jóvenes chilenos dejando un vacío en los contenidos y en la propia historia.La investigación aborda la importancia de educar a las nuevas generaciones para conocer sus pueblos originarios, patrimonio cultural, rescatando las tradiciones mediante el conocimiento de culturas que dieron origen a las manifestaciones que han perdurado profundizando sobre la etnohistoria de la zona central del país, que se ha visto mermada buscando acercar a la comunidad a sus raíces y a desarrollar un sentido de pertenencia.Desde la base historiográfica, pasando por los objetivos de aprendizaje planteados por el Ministerio de Educación y el testimonio de profesores de la provincia de Curicó, se pone a disposición de la comunidad una investigación de historia local aportando en su relato etnohistórico y ahonda en las estrategias utilizadas por los docentes de la provincia de Curicó para aplicar en sus clases contenidos relacionados con el tema, objetivo principal de la investigación. La participación ciudadana es clave a la hora de enfrentar problemáti-cas relacionadas al cuidado patrimonial y rescate de su propia historia, es por ello que desde la enseñanza y aprendizaje de las Ciencias Socia-les se busca establecer una base sólida de conocimientos que permitan a los individuos reconocer en su entorno su identidad y pertenencia con una mirada responsable.
COMPRENDER LA CRISIS. ¿DOMINAN LOS ADOLESCENTES LOS CONCEPTOS ECONÓMICOS?
Authors: Olmos Vila Rafael , Pagès Blanch Joan , González Monfort Neus
Published: November 2024

Este artículo presenta los resultados de una investigación centrada en el conocimiento y el uso de los conceptos económicos por parte de jóvenes de 16 a 18 años ante la actual crisis económica. Estos jóvenes pertenecen a dos grupos de bachillerato de un mismo centro educativo y provienen de contextos socioeconómicos similares. Uno de los dos cursa las asignaturas de Historia Contemporánea y Economía (Grupo A) y el otro no (Grupo B). La información analizada se ha ob-tenido a partir de un cuestionario respondido por el alumnado sobre el tema objeto de nuestro estudio. Los resultados muestran la mayor complejidad del aprendizaje y del uso de los conceptos financieros y la influencia de los medios de comunicación, de la familia y de la escuela en la comprensión de este tipo de conceptos.
“EMPATÍA HISTÓRICA: ESTRATEGIA PARA SU ENSEÑANZA Y APORTES PARA EL ESTUDIO DE LA HISTORIA”
Authors: Moraga Labra Cecilia , Cabello Kanisius Pablo
Published: November 2024

En el presente artículo se examinan los resultados de una experiencia didáctica para el desarrollo de la empatía histórica en estudiantes de 16 y 17 años de edad. El objetivo final de esta investigación es proponer algunos lineamientos generales para el diseño e implementación de estrategias didácticas orientadas a una enseñanza de la Historia a través de la empatía. La empatía histórica, por años cuestionada, plantea múltiples desafíos derivados de una multidimensionalidad cognitiva y afectivo-imaginativa, la que pone en entredicho la prudencia de trasladarla al aula como herramienta para la comprensión de la historia. Para sortear estas dificultades, se propusieron tres pilares orientadores, formulados desde la teoría y reafirmados en la práctica, que en su conjunto guían la planificación de la secuencia didáctica: el trabajo consciente y progresivo en torno al concepto de empatía histórica, el énfasis en el estudio de los contextos históricos y la elaboración de explicaciones empáticas. Se destaca la necesidad de reemplazar una enseñanza de la historia centrada en la memorización de contenidos, para orientarla hacia el trabajo y desarrollo de habilidades, especialmente aquellas vinculadas al pensamiento histórico. Este estudio pretende ser un aporte en este sentido e incentivar, a su vez, más investigaciones y reflexiones en ésta línea.
Presentación
Authors: Vásquez Leyton Gabriela
Published: November 2024

Presentación de la revista.
Ética de Publicación y Declaración sobre Negligencia
Authors: Andamio Equipo
Published: November 2024

Ética de Publicación y Declaración sobre Negligencia
Indice
Authors: Andamio Equipo
Published: November 2024

Indice de la revista.
Indice
Authors: Admin Admin , Equipo Andamio
Published: November 2024

Índice de la Revista
La invisibilidad de las personas en situación de discapacidad en la enseñanza de la historia, geografía y ciencias sociales ¿qué piensa y qué dice el profesorado de historia?
Authors: Admin Admin , Salazar Fernández Marta María
Published: November 2024

El presente artículo recoge las primeras indagaciones realizadas en el marco de la tesis doctoral denominada “La inclusión de las personas en situación de discapacidad en la enseñanza de la historia y las ciencias sociales. Un estudio de caso en la formación inicial docente en universidades del norte de Chile”.La investigación tiene como objetivos: describir las representaciones sociales que posee el profesorado de historia en torno a la invisibilidad de las personas en situación de discapacidad dentro de los contenidos que plantea el currículum escolar de historia y ciencias sociales; identificar como se han construido estas representaciones sociales; y valorar los procesos de inclusión/exclusión que se generan dentro de la clase de historia.El estudio es de carácter cualitativo y exploratorio y los instrumentos utilizados han sido entrevistas semiestructuradas y el análisis documental. Se realizó el análisis de los datos con apoyo del software Atlas. Ti 22.Se observa en los resultados de las entrevistas, la necesidad de humanizar los contenidos trabajados en la clase de historia, lo que permitiría visibilizar ejes de identidad, temáticas y contenidos que han sido excluidos y marginados dentro de la historia escolar.
Parametric Study of Enhanced Combustion Based on Nozzle Protrusion and Spray Angle of High-Power-Density Diesel Engine
Authors: Liu Long , Wang Xinhao , Niu Xiaoxiao , Wang Yang
Published: November 2024

The goal of high-power-density diesel engines is to enhance combustion efficiency and reduce fuel consumption, which has always been the focus of diesel engines in addressing energy and environmental challenges. A high injection pressure allows a significant amount of fuel to be injected in a short period. However, this also increases the risk of spray impingement in small-bore diesel engines. Therefore, optimizing the nozzle protrusion and spray angle to achieve appropriate spray and flame extension is crucial for complete combustion. First, the flame development characteristics of nozzle protrusions ranging from 2 to 5.5 mm were analyzed with fixed spray angles and spray impingement points, respectively. The spray impingement point was optimized by comparing the combustion quality at different spray angles. Finally, the matching of the nozzle protrusion was performed based on the corrected points. The results indicate that the flames in small-bore diesel engines possess significant kinetic energy after impingement. During its development from the piston to the cylinder head, premixed combustion remained dominant. Longer spray penetration promotes the formation of a larger flame surface, and the combination of different nozzle protrusions and spray angles can alter the adhesion of combustibles along the wall. A smaller spray angle and shorter nozzle protrusion can enhance the thermal efficiency by 3.7% and reduce the heat loss by 0.2%, respectively. This research provides valuable insights for optimizing the design of fuel injection parameters and combustion chamber shapes for small-bore diesel engines.
Methanol Combustion in Compression Ignition Engines with a Combustion Enhancer Based on Nitrates (CEN): Insights from an Experimental Study in a New One-Shot Engine (NOSE)
Authors: Samson Richard , Morin Anne-Gaelle , Foucher Fabrice
Published: November 2024

Because it can be produced in a green form methanol is envisioned as a potential fuel replacing conventional Diesel fuel to directly reduce greenhouse gases (GHG) impact of maritime transportation. For these reasons, Original Equipment Manufacturers (OEMs) are working to make methanol easier to use in Compression Ignition (CI) engines. While it is an easy to use substance with manageable energy content, methanol has a few drawbacks, such as: high latent heat of vaporization, high auto-ignition temperature. These drawbacks have an impact on the quality of combustion and therefore solutions have to be found and are still being studied to give methanol a Diesel like behavior. One solution is to use a pilot fuel for ignition in quantities that remain high (> 20 %). A previous study carried out at the PRISME laboratory highlighted the possibility of using a Combustion Enhancer based on Nitrates (CEN) at additive levels. Here the CEN impact in methanol is studied through the use of a New One-Shot Engine (NOSE), a high pressure, high temperature (HPHT), optically accessible vessel. Many parameters are explored: the Ignition Delay Time (IDT) by UV analysis and with photomultiplier (PM) which allow for verification, the vapor and liquid penetration by shadowgraphy technique and Diffused Back-Illumination (DBI) and the Lift-Off Length (LOL) also by Ultra-Violet analysis. As much as possible, the spray A conditions (60 bar, 900 K, injection parameters) recommended by the Engine Combustion Network (ECN) were observed. However, to be more representative of the previous study carried out on an engine, the compression temperature was increased to close to 950-1000 K. This study shows that the addition of CEN (5 % by volume) directly blended to methanol allows for a reduction of the IDT, of the LOL and a stabilization of the flame along the jet penetration. This is a fundamental study in order to start understanding the effect of the additive on methanol.
Experimental Investigation on Combustion Strategy of Light Duty GCI Fueled High Reactivity Gasoline Fuel
Authors: Qahtani Yasser Al , Sellnau Mark , Yu Xin
Published: November 2024

Diesel engines are largely used as power units with high fuel efficiency. Conversely, they have an adverse impact on the environment and human health as they emit high NOx and particulate matter emissions. As more stringent regulations for emissions are introduced, low temperature combustion strategy such as Gasoline Compression Ignition evolved and demonstrated the potential to reduce the particulate matter and NOx emissions by operating engines under a Partially Premixed Combustion mode. Therefore, a 0.55 mm single cylinder engine (Gasoline Direct Injection), was tested over range of engine loads with constant speed (1500 rpm) using RON80 without oxygenates. Different operating parameters such as injection, exhaust gas recirculation (EGR) etc. were used to control combustion phasing and mixture stratifications.

At low loads, rebreathing of hot exhaust gas produced low levels of NOx and smoke emissions. It reduced NOx by 60% and smoke levels below 0.20 FSN when it is coupled with low levels of EGR. At medium to high loads, alternative injection strategies were explored to find proper combustion mode with very low NOx of 0.01 g/kwh and smoke of 0.01 FSN emissions while meeting combustion noise targets. Minimum ISFC was measured at 195 g/kwh at 13 bar IMEP.
Investigation of Combustion Stability in an RCCI Engine Using Recurrence Analysis of Cylinder Pressure Data
Authors: Prashar Rajat , Kumar Kamal S. , Yadav Ratnesh Kumar , Maurya Rakesh Kumar
Published: November 2024

The Reactivity Control Compression Ignition (RCCI) engine, with its dual fuel system and coordinated injection strategy, offers superior emission control and fuel efficiency compared to conventional diesel engines. However, cyclic variations leading to engine combustion instability poses a significant challenge to their development and commercialization. In this study, statistical (COV and Histogram) and nonlinear dynamic (Recurrence Plot and its Quantification) analysis techniques are applied on the time-series data obtained from a single-cylinder diesel engine modified to operate in CNG-Diesel RCCI mode. The engine, while advancing the main injection timing (SOI-2), is tested under various operating conditions, including different engine loads, direct injection mass ratios (DIMR) and port fuel injection (PFI) masses, to help identify the configurations with better temporal correlations and deterministic traits. Such configurations hold potential for control strategy implementation. Through this study it is found that the engine operates in RCCI mode primarily at intermediate to advanced SOI-2 timings. After comparing RQA results of IMEP, Pmax, and CA50; IMEP is determined to be ideal for recurrence analysis. Ultimately, the configuration with a 70-30 DIMR at higher load and higher PFI mass demonstrates superior deterministic traits compared to the other test cases.
Towards Robust Hydrogen Combustion: Precise Lube Oil Consumption Measurement as an Enabler for Tackling Pre-Ignition
Authors: Rossegger Bernhard , Grabner Peter , Gschiel Kevin , Vareka Martin
Published: November 2024

The use of carbon-free fuels, such as ammonia or hydrogen, or at least carbon neutral fuels, such as green methane or methanol is one of the most important paths in the development of low-carbon internal combustion engines (ICE). Especially for large, heavy-duty engines, this is a promising route, as replacing them with battery electric or fuel cell drives poses even greater challenges, at least for the time being. For some applications or areas of the world, small ICEs for trucks, passenger cars or off-road vehicles, operated with alternative fuels will still remain the means of choice. One of the biggest challenges in the development of hydrogen combustion engines is achieving high compression ratios and mean effective pressures due to combustion anomalies, caused by the low ignition delay and broad flammability limit of hydrogen. Oil droplets are considered to be one of the main triggers for pre-ignition and knocking. This paper will give a brief introduction, showing the results of studies on the contribution of oil droplets to combustion anomalies. In this study, oil droplets were artificially injected into the intake manifold in order to trigger pre-ignition. As the correlation between these two phenomena was clearly seen, the second part of the paper will focus on the measurement of oil consumption, which is an important way to combat combustion anomalies. To this end, three innovative measurement technologies were compared. The first method is based on the balance of carbon entering and leaving the combustion chamber. The second method is based on the use of deuterium, which is added to the engine oil as a tracer. The third method is based on measuring the unburnt portion of hydrocarbons with a time-of-flight mass spectrometer (TOF-MS). All methods provide very similar qualitative results. The deuterium and the carbon method show very good quantitative congruence as well and are therefore considered to be very precise and. The respective advantages and disadvantages are shown in the discussion chapter.

Additionally, measurement data will show the influence of the hydrogen production (green vs. grey) on its isotopic ratio. This can be a measure for classifying hydrogen without knowing the exact source.
Fuel Quality Assessment of Green Diesel Produced from Waste Cooking Oil
Authors: Chellachamy Adhikesavan , Krishnasamy Anand
Published: November 2024

Waste cooking oil can be converted into fuel for internal combustion (IC) engine applications by transesterification or pyrolysis. Transesterification results in the production of fatty acid methyl esters called biodiesel. The variability in biodiesel composition and properties from diesel fuel leads to engine re-calibration that requires significant time and effort. Diesel-like hydrocarbons can be produced by catalytic pyrolysis of used cooking oil. Such fuel can be used as a drop-in fuel in IC engine applications. Hydrogen at high pressures and a catalyst generally promote deoxygenation during pyrolysis. Recently, novel heterogenous acid catalysts such as Ni-impregnated activated carbon (AC) and Ag-Co-impregnated AC catalysts were developed to produce deoxygenated fuel by pyrolysis at atmospheric pressure without using hydrogen. Homogenous base catalysts such as sodium hydroxide can also be used in pyrolysis to produce diesel-like fuel. The present work compares the suitability of pyrolysis oils produced from waste cooking oil using these catalysts with those produced without a catalyst. The reaction temperature was optimized for the yield and quality of the fuel. The composition of the diesel-like fuel thus produced is measured using GC-MS. Physicochemical properties such as cetane index, viscosity, density, flash point, and caloric value were measured following the ASTM standard test procedure. The results show that the reaction temperature significantly influences the kinematic viscosity of the pyrolysis oil. It is found that compared to the pyrolysis oil produced without a catalyst, the oil produced using acid catalysts had a higher calorific value. The increase in calorific value is because of the deoxygenation reactions promoted by the catalysts. The pyrolysis oils had physicochemical properties in the range of petroleum diesel. The present study shows that pyrolysis of used cooking oil without hydrogen using acid and base catalysts can produce high-quality diesel-like fuel for IC engine applications.
The Single Technology Matrix Process for Fully Formulated Engine Oil Capability Testing
Authors: Zielinski Christine , Scinto Philip , Chen Min , Gibbons Greer , Baker Charles
Published: November 2024

The American Petroleum Institute’s (API) Single Technology Matrix (STM) is a data-based, Virtual Testing process and protocol (utilizes test data, characteristics and features of base stocks and blends coupled with statistical methods and analysis) used to predict the performance capability of a specific engine oil additive technology in a single specified base oil, in a given engine test. The concept was first introduced in 2002, codified and implemented by API in 2007, and updated in 2022. The previously published advantages of STM in the proof-of-performance of engine oils, remain relevant.

These advantages include a data space focused on interpolation, documented statistical analysis protocol, limitation to a specific formulation, flexibility in understanding complicated, interactive, or non-linear technology and base oil relationships, and timeliness.

There have been numerous changes to, and in, the engine oil industry since the introduction of STM in 2007. These include advances in base stock refining practices, improvement in additive technology, lower viscosity oils, supply chain issues due to local and global disruptive events, test capacity issues due to stalled industry growth and increased regulatory practices. The enhancement of the STM process for both 2022 and beyond is warranted and justified in response to these changes.

This paper serves as an educational tool, not an instructional manual, on the STM concept to enhance understanding and perspective of the current concept not provided elsewhere, as well as the improvement of the process to address the evolving performance testing and base oil characterization needs of the future. It is an important first step in the necessary continuous dialogue on the protocol and the future data needs to support the protocol.
The Effect Mechanism of Grain Size with Nanoscale and Microscale on Physical and Chemical Properties of Cu/SSZ-13 SCR Catalyst
Authors: Chen Yajuan , Lou Diming , Zhang Yunhua , Tan Piqiang , Fang Liang , Hu Zhiyuan
Published: November 2024

Selective catalytic reduction (SCR) technology is currently one of the most effective methods to reduce NOx emissions for engine. NH3-SCR technology is also considered to be the most promising hydrogen engine after-treatment device. This paper used Cu-SSZ-13, which is widely commercially available, as the research object, and explored the relationship between micron and nanoscale grain sizes through experimental methods such as BET, XRD, NH3-TPD, UV-vis-DRS and activity testing, the influence mechanism of micron-scale and nano-scale grain size on the morphology and properties of Cu/SSZ-13 catalyst was explored. The results show that the fresh nanoscale 900F sample has higher low-temperature NOx conversion efficiency, while the micron-scale 1800F sample has poor low-temperature activity and better high-temperature activity. This is closely related to its morphological characteristics, adsorption and desorption characteristics and dual-site properties. The specific surface area and total pore volume of the 900F sample are larger, but according to the diffraction peaks in XRD, its crystallinity is low, resulting in the high temperature activity of the 1800F sample being higher than that of the 900F sample. After SO2 poisoning, the proportions of strong Lewis acid sites and Brønsted acid sites increased, resulting in an increase in both low-temperature and high-temperature activities of the 900S sample. And the activity of micron-scale samples decreases sharply, and the high-activity temperature window shrinks.
Ensemble Machine Learning Techniques for Particulate Emissions Estimation from a Highly Boosted GDI Engine Fuelled by Different Gasoline Blends
Authors: Stangierska Marta , Bajwa Abdullah , Lewis Andrew , Akehurst Sam , Turner James , Leach Felix
Published: November 2024

Light-duty vehicle emissions regulations worldwide impose stringent limits on particulate matter (PM) emissions, necessitating accurate modelling and prediction of particulate emissions across a range of sizes (as low as 10 nm). It has been shown that the decision tree-based ensemble machine learning technique known as Random Forest can accurately predict particle size, concentration, and accumulation mode geometric standard deviation (GSD) for particulate emission diameters as low as 23 nm from a highly boosted gasoline direct injection (GDI) engine operating on a single fuel, while also offering insights into the underlying factors of emissions production because of the interpretable nature of decision trees.

This work builds on the prior Random Forest research as its basis and further investigates the relative performance of five decision tree-based machine learning techniques in predicting these particulate emission parameters and extends the work to 10 nm particles. In addition to Random Forest, the selected techniques consist of four gradient boosting models: GBM, XGBoost, LightGBM, and CatBoost. Moreover, the influences of fuel chemistry are assessed by using data from 13 gasoline fuel blends, including blends with ethanol and methanol – common bio- and e-fuels. The results show that the CatBoost model achieves the highest prediction accuracy (R2 between 0.77 and 0.932), even when the feature set is reduced to improve computational efficiency. Random Forest and LightGBM are also shown to be suitable for PM emissions estimation. Permutation feature importance was used to highlight the dependence of PM emissions on both fuel and engine operating parameters – offering new insights into the effect of fuel properties on particulate emissions and their formation in highly boosted engines.
Evaluating the Ratcheting Performance of Park Lock Mechanism for Electric Drive Unit Using Multibody Dynamics Approach
Authors: Deshmukh Shardul , Kakade Shriram
Published: November 2024

The Electric Drive Unit (EDU) is an essential system in electric vehicles. One of the important features in an EDU is the Park Lock. This safety device prevents the vehicle from unwanted rolling on grades, by locking the transmission. To prevent catastrophic damage to the mechanism, the park lock must also be designed so that it does not inadvertently engage above a specified maximum speed. These two objectives are accomplished by means of a pawl and ratchet gear mechanism which completely engages below a critical speed. Above that speed, the ratchet gear will continue to rotate freely while the pawl will maintain intermittent dynamic contact, but not fully engage (i.e., “ratcheting”).

Although physical testing is used to verify the performance of a park lock, this expensive and time-consuming approach is infeasible at the design stage, when test results might be most useful. To address this, various computational methods are employed to predict the critical engagement speed early in the design process. One such method is multibody dynamic (MBD) analysis. Typically, an MBD analysis is performed by simulating an inadvertent park lock actuation while the vehicle is moving well above the maximum specified engagement speed. The vehicle is then gradually decelerated while ratcheting occurs, until finally, the pawl locks into the ratchet gear at the critical speed, causing the vehicle to stop.

Experience has shown that a single MBD simulation or a single physical test is inadequate to validate a park lock design. In practice, small variations in input parameters or operating conditions can cause large variations in results. This is due to the extreme nonlinearity of numerous dynamic impact events between the pawl and ratchet gear geometries. Examples of such input variations include key parameters like contact stiffness, friction coefficients, geometrical tolerances, part initial conditions, and even computational solver settings.

To address this limitation, the present work uses the ADAMSTM MBD software in conjunction with a Design of Experiments approach, to perform hundreds of simulations that determine a comprehensive range of engagement speeds. Key input parameters are automatically varied using a Monte Carlo strategy. The proposed method is validated with physical testing wherein a range of predicted engagement speeds are well correlated. It shows the reliability and applicability of proposed approach to reduce development time and cost with improving safety in electric vehicles.
Advancing Fuel Cell Testing Environments: Overcoming Limitations in Conventional Humidification Methods
Authors: Braun Katharina , Luetzenkirchen Johanna , Weiss Lukas , Wensing Michael
Published: November 2024

In the field of polymer electrolyte membrane fuel cells (PEMFC), significant research has focused on the membrane electrode assembly (MEA) and electrochemical characterization methods. For real applications optimizing the fuel cell system (FCS) design is essential, requiring careful monitoring of electrochemical and thermodynamic process parameters such as pressure, temperature, relative humidity, heat flux, and gas composition. These operating conditions, provided by balance of plant (BoP) components, significantly impact FCS efficiency, especially relative humidity, which demands high energy input. The first step in a system development involves comprehensively characterizing the MEA by mapping a wide range of operating parameters, not just peak performance points, which are not necessarily the most beneficial for the FCS. This requires precise and dynamic adjustments of process parameters during testing to capture all relevant data efficiently. Currently available test stands lack the capability for high throughput testing with sufficient data accuracy. This paper addresses the essential attributes of an ideal testing environment for fuel cells, using relative humidity as a key example. It examines the limitations of conventional humidification methods, such as slowly adjustable bubble humidifiers. Experimental characterization of a bubble humidification system revealed inaccuracies of up to 5 °C in dew point temperature, leading to a deviation of up to 25% in relative humidity depending on the fuel cell temperature. The reproducibility and accuracy of this humidification technique are evaluated, demonstrating an optimal operating range for a bubbler and boundary regions where it functions less accurately. Basic requirements for humidification units for fuel cell test stands are derived. A proposed solution involves precise mass flow control of the water, which is the focus of future work. In summary, this paper represents a crucial step towards faster and more accurate testing methods, ensuring the precise adjustment of operating conditions to optimize system design and efficiency.
Complex and Nonlinear Resistance Changes of NMC/Gr Cells during Ageing
Authors: Stocker Richard , Mumtaz Asim , Lophitis Neophytos
Published: November 2024

Li-ion battery cell degradation has a strong impact on vehicle performance through performance degradation and deviation from original control calibration. Ageing leads to complex changes in resistance, arising from various contributions. This results in non-uniform resistance changes with temperature and state-of-charge (SoC) as well as altered time-based dynamic responses to current application. This study examines in detail the complex resistance changes with ageing and the dependencies on temperature, SoC and time. The paper evaluates data from a 9-month Nickel-Manganese-Cobalt (NMC)/Gr cell aging study at 45°C, using both frequency and time-based methods. Electrochemical Impedance Spectroscopy with Distribution of Relaxation Times is employed for frequency analysis, while time domain data is extracted from monthly Hybrid Pulse Power Characterization tests. The combination of frequency and time based data allows identification of the individual resistance features that change with ageing (e.g. ohmic, charge transfer and diffusion resistances). Frequency analysis is conducted at various voltages and temperatures to illustrate relative resistance changes, while time domain data includes multiple SoC points to depict monthly resistance trends with SoC. The results indicate several significant results. Resistance decreases substantially in early life followed by a slow subsequent increase. At low temperatures, resistance stays significantly lower even at end-of-life relative to beginning-of-life, while at high temperatures the opposite is observed. This results from a combination of charge transfer decrease and ohmic increase. Time constants of all resistances also significantly increase with aging, altering dynamic response. These findings suggest that simple metrics like a single number state-of-power measurement are not sufficient for measuring aging, and a more sophisticated approach incorporating modeling and efficiency optimization is needed.
Ionization Based Sensor for Early Detection of Thermal Runaway Events in Lithium-Ion Batteries
Authors: Mansour Youssef
Published: November 2024

Lithium-ion and lithium-metal battery cells are susceptible to a phenomenon known as thermal runaway under failure conditions. Given their widespread use in applications such as electric vehicles, portable electronics, and energy storage systems, early detection of thermal runaway is crucial for ensuring the safety of these battery systems. Thermal runaway entails a rapid escalation in battery cell temperature accompanied by the emission of flammable lithium ions, particulates, electrons, hydrocarbons, and hydrogen gases. These gases pose a significant ignition risk, potentially leading to fires and endangering occupants and bystanders. Therefore, the timely detection of thermal runaway is paramount for ensuring safety in proximity to such battery systems. Traditionally, thermal runaway sensors comprise intricate assemblies of pressure, temperature, and gas sensors, strategically positioned at the pressure relief valve of battery modules. Calibration of all sensors is essential to reliably detect thermal runaway conditions. An alternative method for thermal runaway detection involves the identification of ions and free electrons present in the gases emitted by the battery, utilizing ionization techniques. This paper presents an experimental investigation for the early detection of thermal runaway using a novel ionization sensor. The setup involves the placement of a fully charged battery pouch cell on a heater equipped with thermocouples and cell voltage measurement. The cell is enclosed within a container with a controlled opening to the atmosphere. A detailed analysis of the ionization signal was compared with the thermocouple measurements and battery voltage. In addition, a comparison between sealed and vented pouch cell batteries was made, and the detection of thermal runaway was analyzed. The novel sensor reliably detects early signs of thermal runaway in lithium-ion batteries, often before or during pouch rupture, making it valuable for early warning systems. Its effectiveness across different scenarios highlights its potential for integration into battery management systems to significantly enhance safety protocols.
Battery Electric Transit Bus Safety and Performance Testing: A Review of Current Practices and Correlation to Battery Failure Modes
Authors: Jankord Gregory , Gravante Emanuele , D'Arpino Matilde
Published: November 2024

Transit agencies around the world have been investing in more battery electric buses (BEB) in an effort to combat the growing negative externalities stemming from the use of petrochemicals in combustion transit vehicles. These buses use new propulsion systems based primarily on lithium-ion batteries to cut carbon pollution and promote cleaner, faster, and safer rides. As new electrification technologies continue to penetrate the bus transit market, there is a continuous need to evaluate the safety and performance of these battery electric systems. To meet the safety and performance needs of technologies in transit buses, regulations and standards have been established to define best testing and industry practices.

This paper details the current state of battery standards and regulations in automotive and transit vehicles, with consideration of battery failure modes and effects. Various governments and standard organizations have established numerous different regulations and standards. This paper presents a generalization of established safety and performance testing practices used for BEB. The battery tests presented are independent of specific standards or regulations and represent the majority of battery tests that are required or recommended for BEBs. These safety tests are tied back to the failure modes and effects that these tests are intended to cover. Furthermore, this paper presents a summary of the current gaps in BEB safety and performance testing.
Chromosome-level genome assembly and annotation of the crested gecko, Correlophus ciliatus, a lizard incapable of tail regeneration
Authors: Gumangan Marc A. , Pan Zheyu , Lozito Thomas P.
Published: November 2024

The vast majority of gecko species are capable of tail regeneration, but singular geckos of Correlophus, Uroplatus, and Nephrurus genera are unable to regrow lost tails. Of these non-regenerative geckos, the crested gecko (Correlophus ciliatus) is distinguished by ready availability, ease of care, high productivity, and hybridization potential. These features make C. ciliatus particularly suited as a model for studying the genetic, molecular, and cellular mechanisms underlying loss of tail regeneration capabilities. We report a contiguous genome of C. ciliatus with a total size of 1.65 Gb, 152 scaffolds, L50 of 6, and N50 of 109 Mb. Repetitive content consists of 40.41% of the genome, and a total of 30,780 genes were annotated. Our assembly of the crested gecko genome provides a valuable resource for future comparative genomic studies between non-regenerative and regenerative geckos and other squamate reptiles.

Findings
We report genome sequencing, assembly, and annotation for the crested gecko, Correlophus ciliatus.
TSTA: thread and SIMD-based trapezoidal pairwise/multiple sequence-alignment method
Authors: Zong Peiyu , Deng Wenpeng , Liu Jian , Ruan Jue
Published: November 2024

The rapid advancements in sequencing length necessitate the adoption of increasingly efficient sequence alignment algorithms. The Needleman–Wunsch method introduces the foundational dynamic-programming matrix calculation for global alignment, which evaluates the overall alignment of sequences. However, this method is known to be highly time-consuming. The proposed TSTA algorithm leverages both vector-level and thread-level parallelism to accelerate pairwise and multiple sequence alignments.

Availability and implementation
Source codes are available at https://github.com/bxskdh/TSTA.