bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of ultraviolet radiation on total electron content in global positioning system observations
Authors: Iqbal Fauzan , Saktioto Saktioto , Husein Asnawi , Arifin Nur Aisyah , Abdullah Hewa Yaseen
Published: November 2024

Climate is one of the basic elements for understanding natural phenomena and the development of civilizations throughout history. Climate change determines most of the modifications of human nature and culture, as human must adapt to changing conditions which are sometimes an important element that can enhance or threaten its existence. This study aims to determine the characteristics of changes in the total electron content (TEC) and determine the radiation has influence to TEC through observing the global positioning system (GPS) in the ionosphere. In addition, the TEC is a measure of ionospheric parameters that affect the radiation that occurs. This study uses secondary data obtained from the Cibinong Spatial Global Station in 2008 – 2012. This research was conducted as a comparison of the TEC and extreme ultraviolet (EUV). The method used is a simple statistical method which seeks the maximum and minimum the TEC and EUV data, as well as the correlation method to relate the coefficient of determination TEC and EUV. As the results the maximum TEC value is 55.895 TECU which occurred in 2012 at 7 unit time (UT) and the minimum TEC value is 1.955 TECU which occurred in 2010 at 22 UT. The correlation ratio between the TEC and EUV is directly proportional, where the higher the value of the TEC, the higher the EUV value. In closing, TEC and EUV are influence by solar activity.
Degree-Based Topological Indices of the Benzenoid Circumcoronene Series
Authors: Alameri Abdu , Alsharafi Mohammed , Zeren Yusuf , Modabish Abdelhafid , El Marraki Mohammed
Published: November 2024

This paper deals with some types of topological indices called valency-based indices or degree-Based Indices. Specifically, Multiplicative Forgotten, Multiplicative Yemen, modified Forgotten, modified Yemen, generalized modified first Zagreb, generalized modified sum connectivity, and generalized modified product connectivity indices of the benzenoid circumcoronene series are computed. Moreover, the formulas of polynomials for all these topological indices were derived.
A Novel Method for Designing Electronic Logic Circuits
Authors: Al-Areeqi Abdul Raqib A. Asaad , Al-Humaidi Abdullah A. K. Qahtan
Published: November 2024

This scientific paper presents a novel method for designing single and multi-output electronic logic circuits. The produced circuit consists of two parts. The first part consists of (n-1) XOR gates, where "n" is the number of input signals to the logic circuits. This part is called the linear part of the circuit. The second part is designed by any method used in designing logic circuits. This part called the non-linear part of the circuit. The suggested method can be programmed by any high level programming language to be used on any digital computer especially with the circuits which have a large number of input signals.
A Multi-Scale Stochastic Modeling Framework for Predicting the Onset and Progression of Alzheimer's Disease
Authors: Adegoke Olusola Olaitan , Amoah-Saah Rockson , Adaeze Eze Helen , Chinaza Osondu Prosper , Doe Francis
Published: November 2024

Alzheimer's disease (AD) is a complex neurodegenerative disorder characterized by amyloid-beta accumulation, tau protein aggregation, neuronal death, and neural connectivity decline. We developed a multi-scale stochastic modeling framework to simulate AD progression, integrating molecular, cellular, and network-level processes. Our model consists of three modules: molecular scale (amyloid-beta and tau protein dynamics), cellular scale (neuronal death and inflammation), and network scale (neural connectivity). We simulated the progression of AD over 100 days using Monte Carlo simulations with 1000 realizations. Our results show that amyloid-beta levels increased by 25% ± 5%, tau protein levels increased by 30% ± 6%, neuronal death rate increased by 20% ± 4%, and neural connectivity decreased by 15% ± 3%. Our results demonstrated accurate predictions of AD biomarker fluctuations and disease progression. This framework has the potential to improve early diagnosis and treatment of AD. Our framework offers a promising approach for personalized medicine and targeted interventions in AD treatment.
Scope of Right to Information Act in Enabling Local Development in Nepal
Authors: Sapkota Khila Nath
Published: November 2024

This paper aims to explore the impact and potential of the Right to Information (RTI) Act in advancing local development initiatives in Nepal. Historically, local development governance faced challenges, including limited awareness among stakeholders, delays in service delivery, and issues related to corruption, transparency, and accountability. Enacted in 2007, the RTI Act represents a groundbreaking legislative step, obligating public authorities to actively disclose and disseminate information to support local development efforts. This law empowers citizens to engage more effectively with local authorities, fostering responsive and community-oriented development. The study employs qualitative methods with an exploratory and descriptive approach, using purposively selected case studies from Kathmandu Metropolitan City and Sunkoshi Rural Municipality in Okhaldhunga. The findings highlight that transparency and accountability within local government administration are essential for participatory democracy. Overall, the RTI Act is shown to be a transformative tool for citizens, significantly enhancing governance by supporting transparency, accountability, citizen involvement, and effective local development governance.
Optimizing Procurement Performance Through Effective Planning: A Case Study of TANESCO Dar es Salaam
Authors: Mkasinyagaize Hamadi Ahmadi
Published: November 2024

This study investigates the impact of procurement planning on procurement performance at TANESCO. Despite ongoing efforts by the Tanzanian government to improve procurement systems, inefficiencies persist at the TANESCO Umeme Park office, including issues with substandard goods and services, unmet policy objectives, and poor coordination, which contribute to elevated operational costs. Factors such as inadequate information, planning strategies, capacity building, conflicts of interest, transparency issues, and resource mismanagement further exacerbate these challenges. Previous research highlights the need for a participatory approach involving user departments and stakeholders to enhance procurement processes and optimize resource allocation. Utilizing institutional theory, which focuses on the establishment and evolution of social structures, this study examines how procurement planning, staff competencies, supplier relationships, and resource allocation affect procurement outcomes. The literature review underscores the essential role of procurement planning in improving performance. Empirical evidence indicates that effective procurement planning enhances procurement skills and performance in public organizations. The research specifically assesses the influence of market analysis, budget allocation, and risk management on procurement performance at TANESCO. Findings reveal a strong consensus among respondents regarding the importance of these factors. Market analysis is seen as crucial for better supplier selection and improved procurement efficiency, while inadequate planning leads to increased costs and inefficiencies. Effective budget allocation is highlighted as a key determinant of procurement success, although challenges in integrating it with procurement activities persist. Risk assessment practices are valued but require further refinement to address vulnerabilities. Overall, the study emphasizes the need for integrating strategic planning practices into procurement processes to enhance efficiency and achieve better socio-economic outcomes.
The Spider Stellar Engine: a Fully Steerable Extraterrestrial Design?
Authors:   Center Leo Apostel, Vrije Universiteit Brussel, Belgium, Vidal Clément
Published: November 2024

A long-lived civilization will inevitably have to migrate towards a nearby star as its home star runs out of nuclear fuel. One way to achieve such a migration is by transforming its star into a stellar engine, and to control its motion in the galaxy. We first provide a brief overview of stellar engines and conclude that looking for technosignatures of stellar engines has taken two roads: on the observational side, hypervelocity stars have been the target of such searches, but without good candidates. On the theoretical side, stellar engine concepts have been proposed but are poorly linked to observable technosignatures. Since about half the stars in our galaxy are in binary systems where life might develop too, we introduce a model of a binary stellar engine. We propose mechanisms for acceleration, deceleration, steering in the orbital plane and outside of the orbital plane. We apply the model to candidate systems, spider pulsars, which are binary stars composed of one millisecond pulsar and a very low-mass companion star that is heavily irradiated by the pulsar wind. We discuss potential signatures of acceleration, deceleration, steering, as well as maneuvers such as gravitational assists or captures. Keywords: Pulsars: Spiders, Technosignatures, Stellar engine, Interstellar travel
Constraints on Interstellar Sovereignty
Authors:   Blue Marble Space Institute of Science, Haqq-Misra Jacob
Published: November 2024

Human space exploration and settlement of other planets is becoming increasingly technologically feasible, while mission concepts for remote and crewed missions to nearby star systems continue to be developed. But the long-term success of space settlement also requires extensions and advances in models of governance. This paper provides a synthesis of the physical factors that will constrain the application of sovereignty in space as well as legal precedent on Earth that likely applies to any crewed or uncrewed missions to other stellar systems. The Outer Space Treaty limits the territorial expansion of states into space, but the requirements for oversight of nongovernmental agencies and retention of property ownership enable the extension of state jurisdiction into space. Pragmatic constraints from historical precedent on Earth suggest that new space treaties will be unlikely to succeed and new global space agencies may have limited jurisdiction over states, while hard constraints of the space environment require adherence to technical capabilities, political feasibility, and long-term sustainability. These factors form a three-prong test for assessing the viability of interstellar governance models. This discussion of interstellar governance is intended to further the conversation about sovereignty in space prior to the first intentional launch of any interstellar spacecraft. Keywords: Space Settlement, Space Colonization, Interstellar Travel, Governance, Outer Space Treaty
‘O CANADA’? REPRESENTING CANADIANNESS IN ‘ONE WEEK’
Authors: Beattie Melissa
Published: November 2024

‘It’s been…’

For those of a certain age and/or certain geographic range, that partial lyric was almost certainly read in the voice of Steven Page, the former co-front man of Canadian band Barenaked Ladies (from now BNL). Though Page has since become both a solo artist and part of the Trans-Canadian Highwaymen supergroup and the iconic initial lyric is now sung as a duet between BNL’s multi-instrumentalist Kevin Hearn and drummer Tyler
CfP: conference “US Network Series of the 2000s”. Oct 10-11, 2024 @ Université Paul-Valéry Montpellier 3 (FR). Deadline: April 30, 2024
Authors:   CSTonline
Published: November 2024

Following the conferences devoted to US network series produced from the 1950s to the 1970s (Université Paul-Valéry Montpellier, May 2018), during the 1980s (UPVM, February 2019) or the 1990s (UPVM, February 2020), this conference will focus on network series of the following decade: 2000-2010.
Call for Book reviewers – Critical Studies in Television
Authors:   CSTonline
Published: November 2024

The Book Reviews Section for the journal Critical Studies in Television is interested in adding to our list of possible book reviewers. We are particularly interested in recruiting PhD students who would like to get the experience of writing for a Journal. Guidance will be given about shaping a review, reviews will get sympathetic editorial advice and deadlines can be adjusted to suit personal circumstances.
CfP: Critical Studies in Television special issue “EastEnders at 40: Production, Text & Audiences”. EXTENDED Deadline: Oct 20, 2023.
Authors:   CSTonline
Published: November 2024

Queries about this call for papers should be directed to Rebecca Williams (rebeca.williams@southwales.ac.uk) or Christine Geraghty (christine.geraghty@glasgow.ac.uk) In February 2025, the soap opera EastEnders will celebrate its 40th anniversary. Launching in 1985, the BBC series has long been a staple on British television and remains one of the BBC’s flagship productions.
CfP: Critical Studies in Television Slow Conference. June 24-July 5, 2024 @ online. EXTENDED deadline: Jan 31, 2024.
Authors:   CSTonline
Published: November 2024

Television and Sustainability

In 2015, the UN proposed 17 Sustainable Development Goals that are meant to guide humankind towards a more equitable future on a liveable planet. They address questions of health, society, culture and the distribution of resources while also being aware of the urgency to address climate change.
Event: Film is fabulous! A convention for film collectors, cinema lovers, and vintage television enthusiasts. Oct 29, 2023. @ Leicester (UK)
Authors:   CSTonline
Published: November 2024

De Montfort University’s Cinema and Television History Institute is supporting an initiative to identify, safeguard and catalogue the film and TV collections of private collectors, which will be launched at an event at Leicester’s Phoenix Cinema on Sunday 29

th

October.
Can Groundhogs Climb Trees? [Answer & Facts]
Authors: Frey Erzsebet
Published: November 2024

Have you ever wondered if groundhogs can climb trees? Well, wonder no more! In this article, you’ll explore the fascinating world of groundhogs and their climbing abilities. Groundhogs, also known as woodchucks, are the largest rodents in the ground squirrel family and are relatives of squirrels and chipmunks. Despite their stocky bodies, groundhogs can climb trees, fences, and walls with their long and strong front limbs.
ARE YOU READY FOR SOME FROSTBITE? THE NFL AND STREAMING-ONLY GAMES
Authors: Beattie Melissa
Published: November 2024

I say this as an ardent, lifelong fan of American football, but at this point it seems impossible not to recognise that the NFL is a multibillion-dollar business with a somewhat suspect record on workers’ rights. This is particularly the case when it comes to health and safety (Fainaru-Wada and Fainaru 2013;
Animals Like Badgers
Authors: Frey Erzsebet
Published: November 2024

Are you ready to explore the captivating world of animals that resemble badgers? Look no further! This article will take you on a thrilling journey as we delve into the Mustelidae family and discover 11 fascinating creatures that share physical traits with badgers. From the sleek weasel to the cunning polecat, the enchanting otter to the mighty wolverine, you will be amazed by the diversity and adaptability of these extraordinary beings.
NAI ZINDAGI NAYA JEEVAN (BBC1, 1968-82) AND NAZIA HASSAN
Authors: Das Dipali
Published: November 2024

This post first appeared on the WFTHN blog on 24 May 2024.
Animals That Start With C
Authors: Frey Erzsebet
Published: November 2024

Curious about animals that start with the letter C? Get ready to be amazed! Did you know that there are over 120 species of animals that start with C? From majestic big cats to fascinating marine creatures, this article will introduce you to a wide variety of captivating creatures. Explore the world of Cougars, known for their nocturnal hunting skills and impressive lifespan in the wild.
CfP: edited collection “Small Screen Food: American Identity Through a Culinary Televisual Lens”. Deadline: March 15, 2024
Authors:   CSTonline
Published: November 2024

Title: Small Screen Food: American Identity Through a Culinary Televisual Lens Editors: Urszula Niewiadomska-Flis and Carrie Helms Tippen Proposals (500 words): March 15, 2024 Completed Chapters (7,000 words): August 15, 2024 Salman Rushdie characterized the serial television show “as the novelistic medium of the 21st century,” signifying its emerging importance and elevating its status to a realm traditionally occupied by novels.
Badgers in Florida
Authors: Frey Erzsebet
Published: November 2024

Background information on badgers Badgers are medium-sized mammals that belong to the family Mustelidae, which also includes weasels, otters, and ferrets. There are 11 different species of badgers that can be found all around the world, including North America, Europe, Africa, and Asia. Badgers are known for their distinctive physical characteristics, including a stocky build, powerful legs, and sharp claws that are well adapted for digging.
CfP: conference “Images, Film, and Video of Atrocity”. March 25-26, 2024 @ University of Copenhagen (DK). Deadline: Nov 30, 2023.
Authors:   CSTonline
Published: November 2024

The two-day conference on “Images, Film, and Video of Atrocity” invites scholars and researchers from diverse disciplines to submit their papers and join us in exploring the complex and multifaceted realm of non-fictional representations of atrocity.
Coyote Vs. Hyena [Key Differences & Strength Comparison]
Authors: Frey Erzsebet
Published: November 2024

Are you curious about the key differences and strength comparison between coyotes and hyenas? Look no further! In this article, we’ll explore their physical characteristics, speed, diet, habitat, and conservation status. Coyotes have a slender body, measuring between 3.3 and 4.3 feet in length, while hyenas are stockier, growing up to 5.9 feet.
BABY REINDEER AND THE PROBLEMATIC OWNERSHIP OF BAD FANS
Authors:   Daniel O’Brien
Published: November 2024

Regardless as to whether you have seen it, you probably have some awareness of

Baby Reindeer

, the autobiographical miniseries from Richard Gadd, which was released on Netflix in April 2024. The seven-part drama thriller recounts a stalking experience that Gadd suffered during his twenties while he was attempting to embark on a career as a stand-up comedian.
Data Visualization
Authors: Luciano Giorgio
Published: November 2024

Introduction to Exploratory Data Analysis (EDA)

Exploratory Data Analysis (EDA) is the crucial first step in the data analysis process. Before applying complex statistical models or machine learning algorithms, it is essential to understand the structure, trends, and peculiarities of the data you are working with.
CfP: Feminist Media Histories, special issue on Gender, Media, and Developmentalism. Deadline: Feb 01, 2024.
Authors:   CSTonline
Published: November 2024

CALL FOR PAPERS  Feminist Media Histories: An International Journal  Special Issue on Gender, Media, and Developmentalism Guest Editors: Dalila Missero & Masha Salazkina With this special issue of Feminist Media Histories we invite contributions that explore the historical role of gender within media production explicitly engaged in developmentalist projects.
CfP: edited collection “Football Politics and Cultural Production in Africa: Issues and Discourses”. Deadline: April 30, 2024.
Authors:   CSTonline
Published: November 2024

Call for chapter proposals, working title: “Football Politics and Cultural Production in Africa: Issues and Discourses”. Deadline: April 30, 2024. Editor: Dr. Floribert Patrick C. Endong – University of Dschang, Cameroon Concept Notes In the popular imaginary, sports and politics do not mix.
Why Do Camels Foam At The Mouth? (Find Out!)
Authors: Frey Erzsebet
Published: November 2024

Curious about why camels foam at the mouth? You’ll find the answers here. Whether it’s mating season or the presence of rabies, camels exhibit this behavior for various reasons. Male camels experience hypersalivation during breeding season, accompanied by other signs of being in rut, like displaying their dulla. On the other hand, foaming at the mouth can also be a symptom of rabies, although less common.
CfP: conference “The Many Faces and Spaces of Precarity in the Moving Image”. December 14, 2023 @ online. Deadline: Sept 15, 2023.
Authors:   CSTonline
Published: November 2024

“Another world is not only possible; she is on her way. On a quiet day, I can hear her breathing.” Arundhati Roy
Central Limit Theorem with Dice Rolls
Authors: Luciano Giorgio
Published: November 2024

Dice rolling is a pastime enjoyed by many, whether in board games or games of chance. But have you ever wondered how the sum of multiple dice rolls behaves when you roll them repeatedly? In this blog post, we embark on a journey into the world of dice rolls and the fascinating Central Limit Theorem. We’ll uncover how the sum of dice rolls can transform into a Gaussian distribution as the number of rolls increases.
The Subject-to-Tax Rule in East Africa: Is it Worth it?
Authors: Strachey A.
Published: November 2024

The two-pillar approach focusses on BEPS issues in developing countries to a greater extent than preceding OECD agreements. In particular, the Subject-to-Tax Rule (STTR) is intended to address BEPS risks in low-income countries’ tax treaties. BEPS is undoubtedly a critical issue in East Africa since corporate income tax is an unusually important source of tax revenue in Africa. This article analyses the STTR alongside treaties and domestic law to understand the likely impact of the rule in the region. It also considers the diverse domestic policy landscapes to explore whether the STTR is an attractive measure for countries in East Africa. The author believes that implementation of the rule will be complex, challenging already stretched tax administrations. Furthermore, some low-income countries may prefer not to engage with reforms that increase source taxation. The analysis concludes that any hopes that the STTR will mark a major step in addressing BEPS in this part of the world are likely to be disappointed, but it could form part of a portfolio of measures for some specific countries.
Perceived positive teacher leadership and academic performance among university students in Zhejiang Province: The chain mediation of gratitude and subjective well-being
Authors: Zheng Junpeng , Wang Hsuan-Po
Published: November 2024

This study investigates the relationship between perceived positive teacher leadership and academic performance among university students in Zhejiang Province, focusing on the mediating roles of gratitude and subjective well-being. A survey of 678 university students was conducted using the Positive Teacher Leadership Scale, Gratitude Scale, Subjective Well-Being Scale, and Academic Performance Scale. Results revealed that perceived positive teacher leadership positively correlates with gratitude, subjective well-being, and academic performance. Additionally, gratitude and subjective well-being mediate the relationship between teacher leadership and academic performance. The findings suggest that positive teacher leadership influences academic performance both directly and indirectly through gratitude and subjective well-being.
Estudio del contacto entre un penetrador rígido y una probeta de aluminio considerando carga normal y desplazamiento tangencial usando el metodo de los elementos finitos
Authors: Negrín H. Luis I. , Souza Roberto M. , Pérez R. Eduardo A.
Published: November 2024

El objetivo de este trabajo es estudiar los campos de tensiones y deformaciones plásticas obtenidos como consecuencia de la aplicación de carga normal al mismo tiempo que se aplica desplazamiento tangencial de un penetrador rígido sobre una probeta de aluminio. La simulación por el Método de los Elementos Finitos (MEF), utilizando el software ABAQS fue usado para evaluar las tensiones y los campos de deformaciones. El fenómeno fue simulado con una malla bidimensional, asumiendo el estado plano de deformaciones. La carga normal fue aumentada progresivamente (0  50 N) en función del desplazamiento. Los resultados fueron obte- nidos para diferentes valores del coeficiente de fricción entre el identador rígido y el aluminio de comporta- miento elastoplástico. Los resultados obtenidos permiten la correlación entre los esfuerzos de contacto y el comportamiento elasto-plástico de materiales sometidos a ciertos tipos de ensayos de desgaste. Se verificaron algunos resultados de la literatura, como, por ejemplo, el aumento de las tensiones y deformaciones con el aumento del coeficiente de fricción definido en el contacto. Según el criterio de los autores, en el proceso se re- produce el fenómeno stickslip, lo que hace más realista la simulación y permite profundizar en su estudio.
Caracterização microbiológica de uma emulsão mineral utilizada como fluido de corte nos processos de usinagem
Authors: Amaral Piubeli Francine , Gomes Roberta , De Arruda Olavo Speranza , Parreira De Arruda Maria Sueli , Bianchi Eduardo Carlos , Da Silva Junior Carlos Elias , De Aguiar Paulo Roberto , Catai Rodrigo Eduardo
Published: November 2024

Nas operações de usinagem, a utilização do fluido de corte é essencial para se obter melhores acabamentos superficiais da peça, para minimizar o desgaste da ferramenta de corte, para resfriar e lubrificar a peça e a ferramenta de corte e para remover partículas e fragmentos do corte. Em contrapartida a emulsão águaóleo, usada como fluido de corte, é freqüentemente atacada por microrganismos. Este estudo enfoca aspectos quantitativos dos microrganismos contaminantes do fluido de corte, apresentando ainda características morfológicas e tintoriais das bactérias que degradam esse fluido. São realçadas algumas das alterações nas características iniciais do fluido após a contaminação por microrganismos. Para a coleta foi introduzida uma pipeta de 1 ml no reservatório. A seguir as amostras foram depositadas em tubos e posteriormente semeadas em meio de cultura específico. No momento das coletas foi determinado o pH dos respectivos locais de obtenção das amostras, os quais oscilaram entre 8,05 a 8,35. Os resultados obtidos mostraram que os principais microorganismos contaminantes foram cocos Gram positivos e bacilos Gram negativos, o que permite inferir que a emulsão mineral comportase como um meio de cultivo bacteriano, oferecendo condições para a proliferação desses microrganismos. Igualmente podese afirmar que os agentes antimicrobianos adicionados ao fluido de corte realizam eficaz controle do crescimento populacional de microrganismos. Observouse também um crescimento de colônias diferentes, levandonos a concluir que no reservatório encontramos diversas espécies de bactérias, em conseqüência a esse crescimento houve uma leve acidificação do pH
Reducción del tiempo de la fase de acabado de troqueles para conformado de aceros avanzados de alta resistencia
Authors: López De Lacalle Luis Norberto , Lamikiz Aitzol , Muñoa J. , Celaya Ainoa , Campa Francisco Javier
Published: November 2024

El presente artículo presenta una nueva metodología para reducir el tiempo de mecanizado de la fase de acabado de los troqueles que han surgido para conformar los nuevos materiales conocidos como Aceros Avanzados de Alta Resistencia, actuando en dos ejes operativos. Por un lado se trata de minimizar el error de flexión en el mecanizado de estampas templadas hasta 64 HRC. La introducción de los Aceros de Alta Resistencia ha obligado a las troquelerías a introducir en los útiles de estampación un mayor número de insertos construidos en materiales templados, y de zonas templadas en la superficie. La flexión de la herramienta inducida por las fuerzas de corte puede provocar errores dimensionales inadmisibles. Se propone una nueva herramienta de toma de decisiones en la etapa de CAM para elegir aquella estrategia que minimice la componentes de la fuerza de corte que produce el error de flexión. Se presentan algunos ejemplos prácticos donde se ha aplicado la metodología descrita. En segundo lugar se trata de mantener la rugosidad final dentro de los requisitos definidos por los clientes. Para ello se acaban las formas en condiciones de fresado de superacabado, y posteriormente se aplica la técnica de bruñido con bola (ballburnishing). Se logran acabados por debajo de 0,5 µm Ra. Como resultado final se consigue una disminución del tiempo de construcción del troquel.
Abordagem mesoscópica associada à análise de entalhes para fadiga por fretting EM Ti-6A1-4V
Authors: Ribeiro Mendes Marina Frossard , Araújo José Alexander
Published: November 2024

O objetivo deste trabalho é propor uma metodologia para avaliar o limite de resistência à fadiga de componentes sob condições de fretting. A metodologia proposta baseia-se na aplicação da abordagem mesoscópica proposta por Dang Van associada ao Método da Distância Crítica de Taylor. Dados experimentais envolvendo o contato entre um corpo-de-prova plano e sapatas cilíndricas sob regime de escorregamento parcial são considerados para validar a metodologia. O material de ambos, corpo-de-prova e sapatas, é Ti6Al4V, uma liga aeronáutica. Os resultados dos testes mostraram que o tamanho do contato influencia a resistência em fadiga da montagem apesar de nos diferentes testes o estado de tensão superficial ser idêntico nos pontos mais solicitados (hot spot). O Método dos Elementos Finitos foi utilizado para determinar o campo de tensão cíclico e a metodologia para estimativa do limite de fadiga por fretting forneceu bons resultados para os dados experimentais considerados neste trabalho.
Un estudio comparativo sobre los modelos utilizados para la predicción de vibraciones por contacto dinámico en superficies rugosas
Authors: Sánchez Rodríguez Álvaro , Echeverría Villagómez J.S. , García Rodríguez Francisco Javier , Salas Zuñiga R.
Published: November 2024

En los últimos años, se han propuesto varios criterios que permiten predecir vibraciones por contacto dinámico en superficies rugosas, basados en diferentes suposiciones y modelos mecánicos. El objetivo de este estudio es clasificar los trabajos más relevantes desarrollados en campo y analizar sus principales características: parámetros dinámicos de amortiguamiento, grados de libertad, tipo de fricción, modelo de rugosidad, tipo de carga, etc. El método de solución y otras condiciones relevantes también son considerados. Con ello, se propone un modelo general que incluye la mayoría de las características de los modelos utilizados.
Modelo analítico de rendimiento de engranajes rectos convencionales
Authors: Pleguezuelos González Miguel , Pedrero José Ignacio
Published: November 2024

Muchos de los métodos tradicionales para el cálculo del rendimiento de engranajes cilíndricos se basan en las hipótesis de coeficiente de rozamiento constante y distribución uniforme de carga a lo largo de la línea de contacto. Sin embargo, es bien conocido que la rigidez de la pareja de dientes en contacto no es constante a lo largo del intervalo de engrane. Ello provoca una distribución no uniforme de la carga, que influye notablemente en las pérdidas por fricción, debido a la variación del deslizamiento relativo de las superficies en los distintos puntos de contacto. En este trabajo se estudia el rendimiento de engranajes rectos convencionales, con grado de recubrimiento entre 1 y 2, considerando un modelo de distribución de carga no uniforme obtenido a partir del principio de mínimo potencial de deformación, así como un modelo simplificado de coeficiente de fricción variable a lo largo de la línea de engrane. Se presentan expresiones analíticas de las pérdidas por fricción, la potencia transmitida y el rendimiento. Se presenta asimismo un estudio de la influencia de algunos parámetros geométricos de la transmisión en el rendimiento.
Control de planitud de un banco óptico para la fabricación de cámaras de deriva multicapa para el experimento CMS
Authors: Leal Manuel Daniel , Sander Berit , Timm Lauri , Pérez Díaz José Luis
Published: November 2024

Las cámaras de deriva del detector CMS (Compact Muon Solenoid) son estructuras modulares apiladas unidas por un adhesivo estructural. Estas cámaras se utilizan para la detección y seguimiento de partículas de alta energía - en particular muones – insertadas en el detector global CMS actualmente en funcionamiento en el Consejo Europeo de Investigaciones Nucleares (CERN) en Ginebra (Suiza). En el proceso de fabricación en serie de las mismas, es necesario su ensamblado en superficies con una tolerancia de planitud inferior a 0.1 mm variando la carga soportada por estas superficies entre 0 y 90 kN. Cumpliendo estos requisitos se diseñó, modeló y construyó una mesa de precisión con un coste razonable, utilizándose finalmente cuatro unidades para la fabricación de 70 cámaras de deriva en el Centro de Investigaciones Energéticas Medioambientales y Tecnológicas (CIEMAT) en Madrid (España). En el presente artículo se muestra el proceso seguido para el diseño de dichas mesas y su optimización. Se estudia la deformación de la mesa sometida a cargas que se incrementan hasta alcanzar su máximo valor, analizando cómo afecta el número de soportes y el efecto de realizar taladros en la misma. Se emplea el producto de la deformación máxima por el costo como parámetro de optimización del diseño.
Influencia de la temperatura en el error producido en el proceso de medición de rodamientos
Authors: Colazo Carlos , Costamagna Marcelo , Pesci Martín
Published: November 2024

El objetivo del presente trabajo es determinar si existe influencia de la temperatura en los errores resultantes del proceso de medición de aros de rodamientos de bolas, salidos del proceso de rectificado de pistas, medidos al pie de la máquina y a temperatura ambiente. Se confeccionó un procedimiento para la toma de datos para el rodamiento 6203 – IR, tomando dos muestras de 5 elementos cada una, a las temperaturas ambientes de 9°, 12° y 20°C [8]. Luego se realizó, con el software SPSS vers. 10.0, el procedimiento para pruebas no paraméticas con k pruebas independientes con el objeto de verificar si existe o no diferencia entre el error de medición para las tres temperaturas efectuadas en el muestreo. Para ello se efectuaron las pruebas de KruskalWallis, de las medianas y la de Jonckheere-Terpstra [5]. Además se confecciona un análisis por tablas de contingencia, donde se encuentra que existe evidencia suficiente para rechazar la hipótesis nula H0, por lo tanto confirmar la existencia de dependencia entre las variables temperatura y error en la medición [1]. Para concluir se realiza un análisis ANOVA para confirmar los resultados
Estudio analítico, numérico y experimental de la influencia térmica en mediciones de deformación sobre elementos estructurales
Authors: Vignolo Gustavo G. , Vázquez José A. , Soto Axel J.
Published: November 2024

La medición de deformaciones en elementos estructurales es una tarea que requiere extremas pre- cauciones tanto en el diseño y montaje del elemento de medi ción como en la interpretación de las lecturas. En general, en el cálculo resistente de estructuras se dimensionan los el ementos que la conforman de modo que sean capaces de soportar las cargas aplicadas y que la deformación que éstos sufren no afecte su desempeño normal. Este concepto produce una complicación mayor al momento de medir las deformaciones provocadas por las cargas dado que, como premisa de diseño, tales deformaciones deben ser peque ñas. Como consecuencia, la magnitud de las deformaciones de in terés son del mismo orden que las pr ovocadas por factores externos co- mo es el caso de la dilatación térmica. En este trabajo se estudia la manera en que la dilatación térmica afecta las mediciones de deformación sobre una viga sometida a esfu erzos efectuados mediante el uso de un dispositivo específico, y se presentan alternativas para compensar tales mediciones de modo que la lectura final sólo con- tenga la información deseada. El sistem a de interés se compone de una viga de gran tamaño en la que se dispone un instrumento de medición de deform ación en paralelo y un termómetro que determina la temperatura del am- biente. Las masas invol ucradas en cada uno de los elementos hacen que las variaciones en el tiempo de sus tem- peraturas sean muy distintas y, en consecuencia, también lo son las dilataciones térmicas asociadas. Para com- prender y compensar este fenómeno, se presenta en prim era instancia el estudio del fenómeno físico que vincula el calor aportado al sistema y las ma sas y temperaturas de los elementos i nvolucrados. Los resultados obtenidos son contrastados con medicione s de laboratorio. En segunda instancia se a borda el análisis de mediciones expe- rimentales de campo y se propone un m odelo computacional basado en la op timización de redes neuronales arti- ficiales para discriminar el esfuerzo de la dilatación térmica.
Análise do potencial eólico de uma micro-região utilizando um modelo de camada limite atmosférica
Authors: Molina Valle Ramón , Amado Moreira Gilberto Augusto , Meireles Nascimento Carlos Alexandre
Published: November 2024

O Brasil se destaca no cenário mundial apresentando um dos maiore s potenciais eólicos do planeta. Projetos de construção e instalação de turbinas eólicas são complexos e parâmetros tais como dimensionamento e localização devem ser cuidadosamente analisados. A análise em campo, para definir as melhores regiões para instalação destes equipamentos, requer um gasto elev ado com medições e de tem po para processamento dos dados. Devido a isso, a utilização de códigos comerciais de mecânica dos fluidos computacional (CFD) para estudo da Camada Limite atmosférica tem sido cada vez mais empregada para análise das condições locais de vento. Este trabalho tem com objetivo principal utilizar um modelo de camada limite atmosférica aplicado a micro-regiões para definir os melhores locais de instalação de um gerador eólico de 10 kW de potência máxima na região de Sete Lagoas, próximo de Belo Horizonte, Minas Gerais, Brasil . Para isso foram utilizados como condição de contorno do programa comput acional dados experiment ais coletados de uma estação climatológica, instalada no local pela Companhia Energética de Mina s Gerais-CEMIG, permiti ndo encontrar, através do modelo numérico, os campos de velocidade e direção do vento dentro do domínio de interesse, levantando desta forma o potencial eólico e definindo as regiões mais favoráveis para a instalação do gerador eólico.
Reducción de la reflexión en el interior del puerto de Vila do Porto, Azores
Authors: Neves María Graça , Didier Eric , Robert Miguel , Losada Iñigo
Published: November 2024

Para reducir la agitación en el interior del puert o de Vila do Porto, Azor es, se ha proyectado una modificación del muelle interior de atra que de los ferries, con el objetivo de aminorar la reflexión y disminuir el rebase, sin que con eso se re duzca demasiado el área útil de la dársena portuaria. La solución propuesta es una plataforma de forma triangular en plan ta apoyada en pilares rectangulares, ba jo la cual se ha colocado un talud de escollera para disminuir la reflex ión. Se presentan los resultados de ensayos en modelo físico 3D y los obtenidos con dos modelos numéricos RANS en lo que se refiere a presiones en la plataforma y reducción de la reflexión (el modelo IH-2VOF y el FLUENT).
Estudo para utilização de prensagem uniaxial de ação simples para compactação de corpos moedores utilizada na indústria de placas de revestimentos cerâmicos
Authors: Menegon Bristot Vilson , Menegon Bristot Vilmar , Schaeffer Lirio , Gruber Vilson , Guimarães Filho Leopoldo Pedro
Published: November 2024

a prensagem isostática de pós cerâmicos para a fabricação de corpos moedores, tem-se uma produção muito inferior em relação a produção de placas de revestimentos cerâmicos que possui metodologia de prensagem uniaxial de ação simples, e isto se deve ao fato da complexida de do processo isos tático. Atualmente, a fabricação dos corpos moedores para a indústria cerâmica de placas de revestimentos, só é realizada através do processo isostático, isso porque sua característica físi ca é bem mais complexa que a prensagem uniaxial, pois enquanto na prensagem isostática cons egue-se obter o prensado em forma esférica, o processo uniaxial das placas, simplesmente tem as caract erísticas retangulares e ou quadradas, com uma dete rminada espessura. Com isso realizou-se um estudo para a ut ilização da prensagem uni axial de ação simples para a compactação de corpos moedores utilizada na indústria de placas de revestimentos cerâmicos com processo via úmido.
Velocidad de enfriamiento: su determinación en problemas de templado
Authors: De la Torre Leonor , Berenguer María del Carmen , Oliva Laura , Millán Zulma
Published: November 2024

Los tratamientos térmicos son procesos que se emplean para modificar propiedades mecánicas de los materiales. El temple es uno de los tratamientos té rmicos más usados en aceros, cuya finalidad es obtener mayor dureza y mayor resistencia mecánica. El modelado matemático de procesos de templado de aceros da lugar al estudio numérico del mismo.
La formulación numérica de l proceso de temple ba jo ciertas condiciones, en una pieza de acero, permite obtener la distribución de te mperaturas en todos los puntos de la pieza. Para ello se analizan las singularidades que el problema incluy e y se trabaja con la no linealidad del modelo. La determinación de los perfiles de temperatura es el primer paso para lograr las veloci dades de enfriamiento en los puntos de la pieza. Con ellas se puede de terminar el nivel de dureza del acero.
Estudio micromecánico de la formabilidad de chapas de acero. El análisis factorial como herramienta de post-proceso
Authors: Serenelli Mariano , Bertinetti María , Signorelli Javier
Published: November 2024

La tecnología de fabricación de aceros de ba jo carbono para aplicaciones de embutido profundo se ha orientado al desarrollo de procesos que permitieron in crementar la intensidad de la textura en aquellas orientaciones cristalográficas loca lizadas en la denominada fibra gamma {111}. Esta tendencia tuvo su origen en trabajos de investigación basados en simulaciones numéricas de plasticidad cristalina, los cuales posibilitaron evaluar la influencia individual de cada componente típica de textura en los indicadores de embutibilidad R m (anisotropía normal) y ? R (anisotropía planar). En el presente trabajo se realizaron simulaciones de ensayos de tracción uni axial en 32 materiales virtuales con texturas diferentes, a los fines de evaluar la influencia de la distribución orient aciones cristalográficas sobre los valores de R m y ? R , pero no en forma individual sino desde una óptica de conjunto. Se utilizó para ello un modelo de plasticidad cristalina del tipo autoconsistente, seguido de un post-pr oceso basado en el análisis factorial. Este último permitió cuantificar la magnitud de los efectos acoplados producidos por la presencia de las co mponentes de textura consideradas. Se verificó que, en consonancia con los resultados investigaciones previas, la intensificación de la fibra gamma y en particular orientaciones en tor no a la componente {111}<110>, es crucial en la mejora de la calidad de un acero para embutido profundo, mientras que las componentes localizadas en la fibra alfa {uvw}<110> juegan el rol opuesto. Tanto para R m como para ? R se observa que la interacción de dos factores y mayores son del orden del desvío típico. Esta cuantificación permite validar las consideraciones realizadas sobre la capacidad de conformado del material en rel ación a despreciar tales efectos.
Desenvolvimento de um modelo de gestão educacional voltado para a indústria
Authors: Menegon Bristot Vilmar , Menegon Bristot Vilson , Gruber Vilson , Schaeffer Lirio , Da Mota Alves Joâo Bosco , Castelan Jovani
Published: November 2024

Neste artigo apresenta-se um conjunto de iniciativas que estão sendo desenvolvidas na área de gestão de uma escola de ensino técnico-profissionalizante que tem como mantenedora uma i ndústria de revestimentos cerâmicos, principalmente no que tange a prática do ex ercício dos conceitos de valores (competências e habilidades pessoais), fatores estes essenciais para o de senvolvimento sócio-educativo da comunidade escolar e, sobretudo da relação entre aluno x escola x indústria. Para tanto, a pesquisa explora a educação profissional no Brasil, a qualidade nas instituições de ensino médio/técnico, bem como os egressos por elas formados. A construção de tal modelo ocorre a pa rtir de uma análise ambiental na es cola e na industria l baseada em uma etapa de coleta de dados perceptivos e uma se gunda etapa de coleta de dados evidentes.
Desenvolvimento de um sistema de medição experimental a utilizar no ensaio bulge para a caracterização de materiais em chapa metálica
Authors: Abel D. Santos , Gomes Almeida F. , Mendes Joaquim , Teixeira Pedro , Bessa Pacheco J.
Published: November 2024

A obtenção com sucesso de componentes nas operações de conformação plástica está fortemente dependente do material utilizado sendo a sua caracterização de grande importância para a previsão do seu comportamento. Uma das caracterizações fundamentais do material é a curva de cedência plástica que relaciona a tensão com a extensão e é usualmente obtida pelo ensaio de tração. No entanto a amplitude de deformaçãolimitada obtida neste ensaio tem feito com que o ensaio bulge mereça atualmente um interesse crescente, em virtude dos seus níveis de deformação superiores. Esta necessidade é evidente quando se realiza a simulação numérica de processos de conformação plástica, dado que o comportamento do material pode ser descrito com maior rigor e com menor extrapolação dos dados obtidos experimentalmente. Apresenta-se neste trabalho o desenvolvimento e a incorporação de um sistema de medição mecânico numa máquina hidráulica bulge, que permite uma obtenção contínua da pressão, da curvatura da chapa e da extensão no plano da chapa. Com estes dados é possível a obtenção da evolução da curva tensão-extensão do material até elevados níveis de extensão plástica. São apresentados resultados de simulações numéricas por elementos finitos para a análise de sensibilidades de alguns dos parâmetros influentes nas medições, os quais têm um peso importante no rigor dos dados obtidos de comportamento do material. São ainda apresentados resultados experimentais correspondentes a diferentes materiais, cujos ensaios são obtidos com o sistema experimental desenvolvido.
Estudio térmico experimental y alternativas de usos de dos modelos de cocinas solares en zonas áridas
Authors: Buigues Nollens Arturo F. , Fariello Marcelo , Rojos Esteban
Published: November 2024

Este trabajo tiene como objetivo presentar el estudio experimental del comportamiento térmico de dos modelos de cocinas solares, el concentrador solar parabólico lineal y el horno solar inclinado tipo caja, junto a alternativas de aplicación en forma combinada. Está dirigido a la provisión de agua libre de contaminación, preparación y cocción de alimentos, para la arquitectura regional de zonas áridas alejadas o aisladas. La metodología de investigación considera, procesos de transferencia de calor, estudios de comportamiento térmico solar a nivel experimental y de posibilidades de resolución de necesidades alimenticias. Los resultados demuestran convenientes tiempos de cocción, facilitando su utilización, según costumbres y localizaciones, en refugios y viviendas rurales. Las conclusiones obtenidas sobre los aspectos técnicos, ambientales y socioeconómicos vinculados a los sistemas solares analizados, permiten afirmar que sus aplicaciones en forma conjunta, contribuyen a mejorar a diario servicios domésticos e incrementar funciones y prestaciones.