bluuebunny/crossref_metadata_2025 huggingface dataset:
FAKTOR MEMPENGARUHI NIAT MENGGUNAKAN QRIS PADA SHARIA MOBILE BANKING SAAT PANDEMI COVID-19 (MODIFIKASI MODEL UTAUT 2)
Authors: Saibil Defi Insani , Sodik Fajar , Mardiah Andi Ainun
Published: January 2023

Analisis faktor yang mempengaruhi niat dalam menggunakan QRIS  dimasa pandemi Covid-19 merupakan tujuan dalam penelitian ini. Jenis penelitian ini menggunakan penelitian kuantitatif yang didukung data kualitatif. Ada dua fokus penelitian ini, pertama menguji faktor yang mempengaruhi dan mendorong niat untuk menggunakan. Kedua, melihat faktor lain yang mempengaruhi niat dalam menggunakan. Penelitian mengadopsi model modifikasi teori UTAUT 2. Pengumpulan data dilakukukan  melalui survei menggunakan penyebaran kuesioner dengan pertanyaan terbuka dan pertanyaan    tertutup. Jumlah responden dalam penelitian ini sebanyak 134 responden. Metode non-probability sampling dengan menerapkan teknik purposive sampling digunakan. Sedangkan teknik SEM-PLS digunakan pada analisis data, aplikasi WarpPLS 6.0 untuk uji hipotesis dan SPSS 26 untuk analisis deskriptif dan exploratory. Penelitian ini menunjukkan hasil bahwa sebanyak delapan  hipotesis yang diajukan semuanya diterima sehingga mengindikasikan bahwa masyarakat memiliki  niat yang baik dan merasa kemudahan menggunakan QRIS  pada masa pandemi. Hasil dari penelitian ini diharapkan bisa  menjadi masukan untuk industri perbankan syariah untuk lebih meningkatkan kualitas pelayanan QRIS mobile  dalam hal transaksi keuangan secara digital.
A Randomization P-Value Test for Detecting Copying on Multiple-Choice Exams
Authors: Lang Joseph B.
Published: January 2023

This article is concerned with the statistical detection of copying on multiple-choice exams. As an alternative to existing permutation- and model-based copy-detection approaches, a simple randomization p-value (RP) test is proposed. The RP test, which is based on an intuitive match-score statistic, makes no assumptions about the distribution of examinees’ answer vectors and hence is broadly applicable. Especially important in this copy-detection setting, the RP test is shown to be exact in that its size is guaranteed to be no larger than a nominal α value. Additionally, simulation results suggest that the RP test is typically more powerful for copy detection than the existing approximate tests. The development of the RP test is based on the idea that the copy-detection problem can be recast as a causal inference and missing data problem. In particular, the observed data are viewed as a subset of a larger collection of potential values, or counterfactuals, and the null hypothesis of “no copying” is viewed as a “no causal effect” hypothesis and formally expressed in terms of constraints on potential variables.
Electric Machines with High Specific Power
Authors: Ivanov N. S. , Zhuravlev S. V. , Kharkina O. A. , Zdorova M. V. , Shirokov A. A. , Akhunov M. T. , Sosova D. D.
Published: January 2023

Specific power, defined as the ratio of output power to total mass, is one of the generally accepted figures of merit for electrical machines. Given the growing interest in electric aircraft, developers are trying to demonstrate a high value of this indicator for their products. This paper provides an overview of the projects of electrical machines with high power density, the use of which is promising in aircraft of various dimensions. Projects of the University of Nottingham, the University of Illinois, Siemens, Yasa, and others were considered. An analysis of their technical and technological characteristics and approaches to design, manufacturing, and testing is given.
Alterations in Coronary Resistance Artery Network Geometry in Diabetes and the Role of Tenascin C
Authors: Kiss Attila , Nadasy Gyorgy L , Fees Alexander , Arnold Zsuzsanna , Aykac Ibrahim , Dostal Christopher , Szabó Gábor T , Szabó Petra Lujza , Szekeres Maria , Pokreisz Peter , Hunyady Laszlo , Podesser Bruno K
Published: January 2023

Background: Geometrical alterations in the coronary resistance artery network and the potential involvement of Tenascin C (TNC) extracellular matrix protein were investigated in diabetic and control mice. Methods: Diabetes was induced by streptozotocin (STZ) injections (n = 7–11 animals in each group) in Tenascin C KO (TNC KO) mice and their Wild type (A/J) littermates. After 16–18 weeks the heart was removed and the whole subsurface network of the left coronary artery was prepared (down to branches of 40 μm outer diameter), in situ pressure-perfused and studied using video-microscopy. Outer and inner diameters, wall thicknesses and bifurcation angles were measured on whole network pictures reconstructed into collages at 1.7 μm pixel resolutions. Results: Diabetes induced abnormal morphological alterations including trifurcations, sharp bends of larger branches, and branches directed retrogradely (p < 0.001 by the χ2 test). Networks of TNC KO mice tended to form early divisions producing parallelly running larger branches (p < 0.001 by the χ2 probe). Networks of coronary resistance arteries were substantially more abundant in 100–180 μm components, appearing in 2–5 mm flow distance from orifice in diabetes. This was accompanied by thickening of the wall of larger arterioles (>220 μm) and thinning of the wall of smaller (100–140 μm) arterioles (p < 0.001). Blood flow should cover larger distances in diabetic networks, but interestingly STZ-induced diabetes did not generate further geometrical changes in TNC KO mice. Conclusions: Diabetes promotes hypertrophic and hypotrophic vascular remodeling and induces vasculogenesis at well defined, specific positions of the coronary vasculature. TNC plays a pivotal role in the formation of coronary network geometry, and TNC deletion causes parallel fragmentation preventing diabetes-induced abnormal vascular morphologies.
Progress and Challenges of Understanding Cardiorenal Syndrome Type 3
Authors: Neres-Santos Raquel Silva , Armentano Giovana Marchini , da Silva Jéssica Verônica , Falconi Carlos Alexandre , Carneiro-Ramos Marcela Sorelli
Published: January 2023

The pathologies of the kidney and heart have instigated a large number of researchers around the world to try to better understand what the exact connectors responsible for the emergence and establishment of these diseases are. The classification of these pathologies into different types of cardiorenal syndromes (CRSs) over the last 15 years has greatly contributed to understanding pathophysiological and diagnostic aspects, as well as treatment strategies. However, with the advent of new technologies classified as “Omics”, a new range of knowledge and new possibilities have opened up in order to effectively understand the intermediaries between the kidney-heart axis. The universe of micro-RNAs (miRNAs), epigenetic factors, and components present in extracellular vesicles (EVs) have been protagonists in studying different types of CRSs. Thus, the new challenge that is imposed is to select and link the large amount of information generated from the use of large-scale analysis techniques. The present review seeks to present some of the future perspectives related to understanding CRSs, with an emphasis on CRS type 3.
Transcatheter Edge-to-Edge Repair of Mitral Valve Regurgitation: Closing the Gap to Broaden the Coverage
Authors: Imran Hafiz , Ahmad Khansa , Baig Muhammad , Elgendy Islam Y. , Iqbal Nasir , Ehsan Afshin , Sharaf Barry , Gordon Paul , Saad Marwan
Published: January 2023

Background: Transcatheter edge-to-edge repair of mitral valve (M-TEER) is reasonable consideration in symptomatic patients with severe degenerative mitral regurgitation (MR) who are at high or prohibitive risk of surgical repair or replacement. In symptomatic patients on maximally tolerated medical therapy with severe secondary MR from left ventricular systolic dysfunction, M-TEER is reasonable therapeutic option. Methods: In this review, we present a comprehensive overview of the most recent literature and considerations for M-TEER in patients excluded from key trials. These include patients with cardiogenic shock, acute ischemic MR, atrial functional MR, failed surgical mitral valve prosthesis and pulmonary hypertension. Conclusions: M-TEER is feasible and a reasonable alternative option for these patient populations with a significant clinical benefit. However, randomized clinical trials are needed to ascertain findings from these observational studies.
The Combination of Face Identification and Action Recognition for Fall Detection
Authors: D. Dao Ngu , V. Le Thien , T. M. Tran Hanh , T. H. Nguyen Yen , D. Duy Tuan
Published: January 2023

Falls are a very common unexpected accident that result in serious injuries such as broken bones, head injury. Detecting falls, taking fall patients to the emergency room, and sending notification to their family in time is very important. In this paper, we propose a method that combines face recognition and action recognition for fall detection. Specifically, we identify seven basic actions that take place in elderly daily life based on skeleton data extracted using YOLOv7-Pose model. Two deep models which are Spatial Temporal Graph Convolutional Network (ST-GCN), and Long Short-Term Memory (LSTM) are employed for action recognition on the skeleton data. The experimental results on our dataset show that ST-GCN model achieved an accuracy of 90% that is 7% higher than the LSTM model.
Examining the Attitudes of Turkish Students Towards Scientific Field Trips
Authors: Demir Yılmaz
Published: January 2023

In this research, it is aimed to examine the attitudes of Turkish students attending middle school according to various variables (gender, class level, academic achievement, daily study time, maternal education status, maternal occupation, father education status, father's profession, family income status, number of people living in households). The research is designed according to one of the quantitative research methods, the scanning pattern. The sample group of the study consists of 452 secondary school students who were educated in the central district of Kilis province in the fall semester of the 2021-2022 academic year, aged between 10 and 13, selected using simple unelected sampling method. The data of the research were analyzed using the SPSS 23 program. The research findings reveals that middle school students have a high attitude towards scientific field trips. Student attitudes towards the learning tool and adventure direction, which are the sub-dimensions of scientific field trips, are moderate; student attitudes towards social and environmental aspects are high. It was also concluded that the attitudes of secondary school students towards scientific field trips differed importantly according to gender, academic achievement, study time, parental education level and occupation and number of households. However, it was detected that the attitudes of middle school students towards scientific field trips did not differ importantly according to class level and economic level variables.
The Legalisation of Child Pornography in Sweden and What Followed (1969-1999).
Authors: Svanberg Mikael
Published: January 2023

After some years of debate among intellectuals about the freedom of individuals in relation to the state, sexual intercourse in public was legalised in Sweden in 1971 with an age limit of 15 for participants, and all kinds of printed pornography were legalised without an age limit for those involved. (The representation and private adult consumption of pornography in moving images remained legally unregulated like before.) The reform was similar to a reform that had entered into force in Denmark in 1969. A re-regulation of pornography was carried out during the period 1973-1999. The result of this study shows that although child pornography in print and sexual intercourse in public were criminalised during the rule of conservative Governments (1976-1982), it was not until 1990 that all political parties took a firm stand against child pornography in moving images. The results have been interpreted in the light of the Scandinavian legal realism that characterised Swedish legislation until the 1990s.
The Federal Reserve’s Response to the Global Financial Crisis and its Effects: An Interrupted Time-Series Analysis of the Impact of its Quantitative Easing Programs
Authors: KAMKOUM Arnaud Cedric
Published: January 2023

The financial crisis that started in the U.S. at the end of 2007 and later spread to other countries was the most severe economic and financial disaster since the Great Depression. The crisis began in the U.S. housing market in August 2007, rapidly extended to other sectors of the U.S. economy, and became global following the collapse of various U.S.-based international financial institutions. To counter the negative effects of the crisis, the Federal Reserve (the central bank of the United States) and other central banks conducted monetary policies that are widely considered unconventional. This master’s thesis examines the monetary policies the Federal Reserve implemented in response to the crisis. More specifically, the thesis analyzes the Federal Reserve’s quantitative easing (QE) programs, liquidity facilities, and forward guidance operations implemented from 2007 to 2018.The thesis’ detailed examination of these policies is concluded with an interrupted time-series (ITS) analysis of the causal effects of the QE programs on U.S. inflation and real GDP. The results of this design-based natural experimental approach show that the QE operations positively affected U.S. real GDP but did not significantly impact U.S. inflation. Specifically, it is found that, for the 2011Q2-2018Q4 post-QE period, real GDP per capita in the U.S. increased by an average of 231 dollars per quarter relative to how it would have changed had the QE programs not been conducted. Moreover, the results show that, in 2018Q4, ten years after the beginning of the Federal Reserve’s QE programs, real GDP per capita in the U.S. increased by 14% relative to what it would have been during that quarter had there not been the QE programs.
Craniological data on migrations from the West to Eastern Europe in the Post-Catacomb period
Authors:   Peter the Great Museum of Anthropology and Ethnography (the Kunstkamera) of the Russian Academy of Sciences, Kazarnitsky Alexander
Published: January 2023

In the article the craniology of the post-Catacomb and Middle Volga Abashevo populations in the context of cranial metric characteristics of Neolithic and Bronze Age groups of continental Europe is discussed. The data on 2100 male skulls belonging to 95 samples was analyzed by means of Mahalanobis distances (D²) matrix. The results reveal high level of similarity between the post-Catacomb series and Catacomb East-Manych, Eastern Caucasus (Gintchi) and Fatyanovo-Balanovo samples. Basically these results are in line with archaeological reconstructions of cultural processes in Middle and Late Bronze Age. The most western series, which displays morphologic similarity with the Babino sample, is the Globular Amphora series, while the Corded Ware sample from the Baltic region is similar to the Lolino culture sample. We suggest that the series of skulls from the Pepkino kurgan may be unrepresentative for the Middle Volga Abashevo population, since analogies to its cranial metric profile can be traced only in the late Fatyanovo and Balanovo samples and in one local Yamnaya sample, but are absent in other European populations, including Bell Beaker sample, which is in contradiction with archaeological data.
Geometric forms in the art of the ancient population of the Kola Peninsula
Authors:   Institute for the History of Material Culture of the Russian Academy of Sciences, Shumkin Vladimir , Likhachev Vadim
Published: January 2023

Geometric images on rocky surfaces (petroglyphs and paintings), which abound in the sites of Northern Fennoscandia (more than 300 separate locations), as well as similar symbols on ceramics, bone products, horns, stone handicrafts, do not often attract the attention of researchers. Like figurative images, they, undoubtedly, have been included in the arsenal of creative activities of our distant ancestors since ancient times and reflect their worldview, captured by visual means. Pisanitsy (pictograms) of the Rybachy Peninsula is the only site of its kind in the vast territory of the Russian North. The petroglyphs of Kanozera, along with similar objects from Alta, Vingen (Norway), Nämforsen (Sweden), Vyg, Onego (Karelia) are among the largest (each with more than 1000 images) rock art galleries of the hunter-gatherer tradition of Fennoscandia and remains the only site of this kind in the Russian Arctic. Modern studies of petroglyphs by means of night photofixation technique based on special powerful lighting directed at an particular angle to the surface with engravings, as well other non destructive technical methods, including the use of a technique based on the creation of 3D models using photogrammetry and obtaining “pseudo-rubbings” allow reveling new images and refine the outline already known. Sharing similar geometric patterns with petroglyphs, the ground labyrinths of the Kola Peninsula are made in different from petroglyphs techniques and materials. The labyrinths constructed of small boulders in the bays of the Barents Sea they are frequently used by various “pseudo-analysts” to build their esoteric speculations. Working in the direction of scientific study of these phenomena, trying to demonstrate and analyze the objects of historical and cultural heritage themselves, the authors follow the postulate that true human behavior and its conscious activity, in general, begins with the use of symbols, thanks to which the final separation of man from the animal environment took place.
Nutritional practices of the preschool-aged children and associated factors: A cross-sectional study in Rupandehi district of Nepal
Authors: Sharma Prakash
Published: January 2023

Undernutrition is a common problem among Nepali preschool-aged children. Every parent’s feeding practice should be focused on preventing unhealthy eating behaviors of preschool-aged children as it is very difficult to change it in their later life. This study was carried out to assess the key nutritional practices and associated factors among the 3-5-year-old preschool-aged children from their primary caregivers/mothers by employing a quantitative research method. Data were collected through scheduled interviews and observations from mothers/primary caregivers of 394 preschool-aged children who were selected through a multi-stage random sampling procedure in Rupandehi District of Nepal. Binary logistic regression was done to determine the predictors of nutritional practices of preschool-aged children. A p-value less than 0.05 is considered statistical significance. Economic statuses including caste/ethnicity were the main socio-economic and demographic variables to determine the nutritional practices of the preschool-aged children. Findings of the study indicated that majority of preschool-aged children were found in low-level nutritional practices. The preschoolaged children from marginal economic status, including disadvantage-cohorts of the Terai and Dalit, were the victims of the poor nutritional practices. Hence, community-based nutrition education intervention and mothers/caregivers’ awareness programs on feeding practices may be an incredible effort to improve the nutritional status of preschool-aged children if the program is intervened by targeting the background characteristics of the community group.
Role of social media for sexual communication and sexual behaviors: A focus group study among young people in Nepal
Authors: Regmi Pramod R. , Van Teijlingen Edwin R. , Silwal Ram Chandra , Dhital Rolina
Published: January 2023

Over the past decade, young people’s use of the social media has increased steadily in many countries including Nepal. Studies in other countries suggest that social media platforms can play an important role in facilitating sexual communication and relationships. This qualitative study comprising focus group discussions (FGDs), intends to explore: (a) perceptions of and motives toward social media re. sexual communication in educated unmarried young people in Nepal; and (b) their views of the link between social media and risky sexual behavior. We carried out eight FGD, four with young men and four with young women. FDGs were audio recorded, transcribed and thematically analyzed. All FGD participants were students (age range 15-22) from Kathmandu. Five themes emerged from the thematic analysis: a) use of and motives for using social media; b) sex education in general; c) sexual information through social media; d) social media’s role in forming romantic and sexual relationships; and e) negative experience of social media. Social media are popular among young people in Nepal and is considered as an important platform to access sexual health information. Young people also use these to establish romantic and sexual relationships, however, it doesn’t necessarily mean that social media are directly leading to unsafe sexual behaviors in young people. It is the lack of awareness and inadequate education about sex that is resulting in unsafe sexual practices. Overall, suggesting the need for more appropriate health promotion activities in the field sex and relationship education.
A Proposed National Surveying And Mapping Policy In Nepal
Authors: Adhikary Krishna Raj , Paudyal Dev Raj
Published: January 2023

The political objective of Nepal is poverty reduction and sustainable development. The sustainable land administration and management is a tool to achieve the political objectives. From an institutional perspective, land administration and management includes the formulation of land policy, the legal framework, resource management, land administration arrangements, and land information management. In Nepal, The draft of National Land Policy document has been formulated and it is under discussion at ministerial level. One of the recommendations on that National Land Policy document is the formulation of National Surveying and Mapping Policy. It is realized that the time has come to formulate the "National Surveying and Mapping Policy" based on the proposed National Land Policy document in keeping abreast of development and changes in the global technological environment. In this paper, an attempt has made to prepare National Surveying and Mapping Policy in Nepal. The main issues and challenges are also raised on this paper to formulate the National Surveying and Mapping Policy in Nepal. This paper starts with Background and describes the background for developing this policy document. It then describes about Survey Department activities. It then elaborates the policy on Surveying and Mapping in Nepal with policy on Geodetic Surveys and Space Science, Topographic Survey and Geographical Information Infrastructure, Cadastral Survey and Land Information, Research & Development, Resource, Administration. Finally, it concludes with some concluding remarks.
Assessment of the Digital Cadastre in Nepal from the Cadastre 2014 Vision
Authors: Paudyal Dev Raj
Published: January 2023

In Nepal, the value and price of land in urban areas is very high. Due to the scale constraint, the cadastral maps prepared by graphical cadastral surveying method does not satisfy the land owners as they are asking for the accuracy of centimeter of land in the front face of their land parcel. The land owners are also asking for the recording and documentation of 3D real estate objects. Considering these facts, Cadastral Survey Branch under Survey Department has initiated digital cadastre program focusing on the urban land areas. Last year, the piloting of this program has been successfully completed to prepare digital cadastral database in ward number six of Banepa Municipality, Nepal. After the success of digital cadastral mapping, the programme has been continued and some observations are made. Some lessons have been learned from this programme for the cadastral information system (CIS) development in Nepal. There are various ways to evaluate the cadastral projects. In this paper an attempt has been done to evaluate the digital cadastre programme from Cadastre 2014 perspectives.
From Cuneiform to Comic: Redrawing Sarah in R. Crumb’s The Book of Genesis Illustrated
Authors: Woodyard Kerith M.
Published: January 2023

This article studies Robert Crumb’ s The Book of Genesis Illustrated (2009) , an unabridged graphic novel of the first book of the Hebrew Bible that rankled critics anticipating that Crumb would invest the book’ s ancient narratives with new, subversive meanings. For these detractors, Crumb’ s Genesis Illustrated lacks the transgressive, rebellious qualities of his earlier comics. Contrary to this view, this essay uses Crumb’ s storytelling involving Sarah to demonstrate how Crumb noticeably subverts Genesis’ s androcentrism by adopting a feminist hermeneutics of suspicion that reveals a waning matriarchal priestess tradition implicit in the text and helps explain the confounding wife-sister and barren-mother motifs in Sarah’ s story.
CAMBIOS EN LA GEOPOLÍTICA Y OCUPACIÓN DEL TERRITORIO: PERÚ 2000-2020
Authors: JURADO NÁJERA Joel
Published: January 2023

Con el Consenso de Washington desde 1990 se dio paso al predominio de las inversiones de las empresas transnacionales en la explotación privada de los recursos minero extractivos. Las empresas americanas y europeas adquirieron la mayoría de los yacimientos mineros y energéticos que se encontraban en manos del Estado peruano. Estas siguieron operando bajo el patrón de ocupación territorial tipo enclave, sin mayores encadenamientos con la economía regional ni de su entorno rural. Desde comienzos del presente siglo, la inversión china comenzó a adquirir las empresas mineras con mayor desarrollo tecnológico y potencial futuro, tejiendo a la vez la denominada Ruta de la Seda, sobre la base de corredores económicos transversales diversificando sus inversiones en diferentes líneas de actividad proyectando y modernizando la infraestructura multiviaria en las macroregiones norte, centro y sur conducentes a puertos globales que operarán en red en el litoral peruano del Océano Pacífico desctacando los ferrocarriles y las vías fluviales para la integración bioceánica con Brasil y Bolivia y el Atlántico
GUBERNAMENTALIDAD NEOLIBERAL Y EDUCACIÓN UNIVERSITARIA EN EL PERÚ. UN PROGRAMA DE PROFESIONALIZACIÓN DE ADULTOS EN UNA UNIVERSIDAD DE LIMA
Authors: YALLE QUINCHO Omar
Published: January 2023

El presente artículo aborda desde el concepto de gubernamentalidad neoliberaly educación universitaria en el Perú, el estudio de caso del Programa porExperiencia Laboral Certificada en una Universidad privada de Lima, para conocerla formación de profesionales que forma y que perspectivas tienen sus estudiantes.Metodológicamente, el estudio es cualitativo sustentado en entrevistas y cuestionariosdirigidos. Se concluye que la gubernamentalidad neoliberal es un concepto quepermite analizar la educación universitaria, como un medio de formación delestudiante de la organización de la empresa y el sujeto emprendedor.
ARQUEOLOGÍA DESDE LA ARQUITECTURA. UNA MIRADA AL I CONGRESO INTERNACIONAL DE ARQUITECTURA ANDINA-I CIAA PERÚ 2019
Authors: GUZMÁN JUÁREZ Miguel
Published: January 2023

Se presenta un balance de la realización del “I Congreso Internacional de ArquitecturaAndina-I CIAA Perú 2019”, cuyo objetivo fue mostrar y discutir los aportes de lasinvestigaciones efectuadas por arquitectos dentro del ámbito del conocimiento delas sociedades ancestrales del mundo andino. Sin embargo, se hizo hincapié en lainvestigación interdisciplinaria, de tal manera que dichos estudios deben articularsecon los avances de la disciplina arqueológica, así como de las interpretacionesantropológicas, y éstas considerar a la primera, en el sentido que la arquitecturaimplica la reorganización del espacio donde se desarrollan las diferentes actividadeshumanas, cotidianas y complejas. En esta lógica se propusieron siete simposiostemáticos que permitieron profundizar en ciertos aspectos de sus modos de vida ysus transformaciones. Se pretende construir así renovadas historiografías y repensarlo andino desde la arquitectura.
EL CONOCIMIENTO HEGEMÓNICO Y EL DERECHO HUMANO AL AGUA: EL CASO PERUANO
Authors: PASTOR PAREDES Oscar
Published: January 2023

La Organización de las Naciones Unidas (ONU), desde inicios del siglo XXI, ha desplegado una intensa actividad intelectual y diplomática para incidir en las políticas nacionales de los países miembros, orientadas a alcanzar coberturas universales en agua y saneamiento, aprobados para el periodo 2005 – 2015, en los denominados Objetivos de Desarrollo del Milenio (ODM), que se actualizan y amplían en los Objetivos de Desarrollo Sostenible (ODS) vigentes después del año 2015. El conocimiento internacional afirma la necesidad de “contar con agua en cantidad y calidad suficiente para asegurar la salud y mejorar el bienestar de las personas”; el enfoque de acceso al agua invisibiliza el alcantarillado y posterga la necesidad de mejorar y sostener la gestión de los prestadores. El conocimiento hegemónico nacional, que se desarrolla con aportes del conocimiento global, es determinante para elaborar diagnósticos y aprobar políticas nacionales
Temperature Measurements of Polymer Composite Flat Plates Coated with Aluminum-12Silicon
Authors: Therrien D. , McDonald A. , Mertiny P.
Published: January 2023

The temperature distribution of glass fiber-reinforced epoxy flat plates coated with a thin oxy-acetylene flame-sprayed aluminum-12silicon coating was determined experimentally. The composite plates were fabricated by filament winding. Following winding, but prior to and during curing, garnet sand was uniformly distributed on the glass fiber-reinforced epoxy plate surface. The sand roughened the surface such that there was adhesion of the aluminum-12silicon particles to the surface. A resistive heating wire was attached to the coated surface. Thermocouples were attached to the composite and coating surfaces to measure transient and spatial surface temperature distributions. The spatial temperature of the coating and polymer surfaces decayed uniformly throughout the coating-composite ensemble from the heating wire. It was also observed that the coating served to increase the surface temperature of the coating-polymer system compared to uncoated samples. This was attributed to the large thermal conductivity of the metal coating and the low thickness of the samples.
Microstructure Characteristics and Oxidation Behavior of Molybdenum Disilicide Coatings Prepared by Low Pressure Plasma Spraying
Authors: Niu Y. , Fei X. , Wang H. , Zheng X. , Ding C.
Published: January 2023

Molybdenum disilicide (MoSi2) has been applied as protective coating material on various substrates fabricated by different methods due to its good oxidation resistance at elevated temperature, relatively low density and coefficient of thermal expansion and high thermal conductivity. In this work, MoSi2 coatings were fabricated by low pressure plasma spraying technology (LPPS). Their morphology, composition and microstructure characteristics were intensively investigated by SEM, XRD, EDS and TEM. The oxidation behaviors of MoSi2 coatings were also explored. The results showed that the MoSi2 coating was compact with porosity less than 5%. Its microstructure exhibited typical lamellar character. The MoSi2 coating was made up of grains with irregular shapes and different sizes of 0.1-0.2 µm. It was mainly composed of tetragonal and hexagonal MoSi2 phases. A small amount of tetragonal Mo5Si3 phase formed and randomly distributed in the matrix of MoSi2. The MoSi2 coating exhibited excellent oxidation-resistant behavior at 1773K, which resulted from the continuous dense glassy SiO2 film formed on its surface.
Influence of Parameter Variations on WC-Co Splat Formation in an HVOF Process Using a New Beam-Cutter Device
Authors: Tillmann W. , Hussong B. , Priggemeier T. , Kuhnt S. , Rudak N. , Weinert H.
Published: January 2023

During the last 20 years, numerous scientists have studied the formation of thermally sprayed WC-Co coatings. Most of them focused on the direct connection between parameter variations and coating properties, such as the microstructure, wear or hardness. As the formation of single splats is the foundation for any thermal spray coating, this work focuses on the investigation of single splat morphologies. The aim of single splat interpretation is to determine the influence of different spray parameters on the morphological distribution of particles inside the flame. This distribution is indispensable to understand the formation of each coating layer during the process. Unfortunately, most of the methods presently used for generating single splats do not allow an assignment of each splat to its radial position in the flame. A method to create a footprint of a spray jet with an extremely short exposure time was used in this paper. The resulting field of splats enables the assignment of the splats on the specimen to their radial position in the cross-section of the spray jet. The footprints were analyzed by correlating the quantities and morphology of the splats to measurements of the spray jet properties and the splat’s radial position inside the jet.
Engineering HVOF-Sprayed Cr3C2-NiCr Coatings: The Effect of Particle Morphology and Spraying Parameters on the Microstructure, Properties and High Temperature Wear Performance
Authors: Poirier D. , Legoux J.-G. , Lima R. S.
Published: January 2023

Chromium carbide-based thermally sprayed coatings are widely used for high temperature wear applications. In these extreme environments at those temperatures, several phenomena will degrade, oxidize and change the microstructure of the coatings, thereby affecting their wear behaviour. Although it can be easily conceived that the Cr3C2-NiCr coating microstructure evolution after high temperature exposure will depend on the as-sprayed microstructure and spraying parameters, very little has been done in this regard. This study intends to develop a better understanding of the effect of spraying parameters on the resulting chromium carbide coating microstructure after high temperature operation and high temperature sliding wear properties. The microstructures of different coatings produced from two morphologies of Cr3C2-NiCr powders and under a window of in-flight particle temperature and velocity values were characterized through X-ray diffraction (XRD) and scanning electron microscopy (SEM). Sliding wear at 800°C was performed and the wear behaviour correlated to the spraying parameters and coating microstructure. Vickers microhardness (300 gf) of the coatings before and after sliding wear was also measured.
Development of the Particle Interface Bonding in Thermal Spray Coatings for Expanding High Performance Applications
Authors: Li Chang-Jiu , Yang Guan-Jun , Li Cheng-Xin
Published: January 2023

Thermally sprayed coatings are formed through the successive impact of molten droplets and/or semi-molten particles followed by flattening, rapid cooling, and solidification. Individual droplets flatten to form splats of several micrometers in thickness upon impact and result in the formation of a coating that has a lamellar structure with limited interface bonding. The inclusion of semi-molten particles in the coating modifies its microstructure. The bonding between particles dominates coating properties and performance. This review paper examines the bonding formation at the interface between thin lamellae in the coating. The effect of spray parameters on the bonding ratio is presented to reveal the main droplet parameters controlling bonding formation. It is shown that spray particle temperature dominates the bonding formation more than particle velocity. Significant increases in ceramic particle temperature are not possible due to the inherent characteristics of thermal spray processing; therefore, the bonding ratio is limited to a maximum of about 32%. On the other hand, it was found that through controlling the surface temperature of coating prior to molten droplet impact, the bonding at the lamellar interface can be significantly increased. Consequently, with the proper selection of deposition conditions and control of surface temperature, the bonding ratio of ceramic deposits can be altered from a maximum of 32% for a conventional deposit to the maximum of 100%. Such wide adjustability of lamellar bonding extends the applicability of plasma spray coatings to applications requiring different microstructures and properties. Moreover, this bonding control makes it possible to fabricate porous surfaces and structures through the deposit of surface-molten particles, to deposit high temperature abradable ceramic coatings, and to form super-hydrophobic surfaces. Furthermore, the ability to deposit coatings with complete interface bonding allows crystalline structure control of individual splats through epitaxial grain growth.
Casting Requirements on Light Metal Crankcases for Thermally Sprayed Fe-Based Bore Coatings
Authors: Ernst F. , Kube D. , Klaus G.
Published: January 2023

Since 2000, cast iron-liners have been replaced in several engine projects by Fe-based thermally sprayed coatings in the bores of a light metal crankcase. In contrast to cast in liners the linerless versions of these Al-crankcases are very demanding with regard to the porosity and tensile strength in the areas around the bores. The casting porosity has to be diminished to maximum pores smaller than 1mm² due to the roughening procedure, either mechanical roughening (MR) or high power water jet roughening (WR), in order to prevent either tool failure (MR) or widened pores (WR). At Nemak Dillingen these challenges are met by the Core Package Process (CPS), offering the advantages of a highly flexible casting design and a nearly unlimited choice of the cast alloy. These boundaries enable the production of lightweight crankcases made of the strong and creep resistant Al-Si-Cu based secondary alloy A319. The high quality of the cylinder bore surface is achieved by a carefully designed thermal household of the solidifying casting. The cylinder chill form a stable and sound shell in the very beginning of solidification, whereas feeding takes place from the sidewall structure of the crankcase. At the same time, specially designed chills for the bearing seat enable a very short solidification time, the resulting properties are crucial for highly loaded diesel engines. After casting and machining, the crankcases have been mechanically roughened and coated with 0.8 % C-Steel. The coatings and the interface between the coating and the casted Al-substrate have been investigated by means of light microscopy regarding the interlock between coating and substrate and the near-surface porosity of the cast metal.
Study of Delamination Induced by Laser-Drilling of Thermally-Sprayed TBC Interfaces
Authors: Guinard C. , Guipont V. , Proudhon H. , Jeandin M. , Girardot J. , Schneider M. , Berthe L. , Martin A.
Published: January 2023

The efficiency of aero-engines combustion chambers with thermal barrier coating (TBC) is improved when numerous cooling holes are laser drilled with inclined angles. However, during the laser drilling process, especially in the percussion mode, a detrimental crack can be generated at the TBC interface. Thus, each hole could be edged with a non-visible delaminated area underneath the ceramic top-coat. The present work is focused on the thorough study of the delamination induced by laser percussion drilling when interrupted drilling conditions are presented. Shallow angle drilling was applied on separated holes with 1 to 4 laser pulses respectively and various acute incident angles. Crack length was assessed by conventional metallographic preparation. A special experimental method was carried out in order to inspect the delaminated interface and the lateral edge of a semi-hole. This non-destructive assessment of the delamination of laser drilled TBC was complemented by a 3D imaging of a semi-hole using X-Ray microscopy. Results are presented with attention on both crack initiation and propagation during the laser percussion drilling of plasma-sprayed TBC.
Formation of Abradable Alumina Ceramic Coatings through Deposition of Semi-Molten Ceramic Particles by Flame Spray
Authors: Zou J. , Li C.-J. , Huo H.-B. , Chen B. , Li C.-X. , Yang G.-J.
Published: January 2023

High temperature gas turbines require ceramic abradable coatings for sealing to ensure high efficiency. In this study, a novel method is proposed to deposit porous ceramic coatings through deposition of ceramic spray powder particles in the semi-molten state. The commercially available alumina (Al2O3) powders were spheroidized and screened to a particle size range from 40 to 50 µm for spray deposition. Flame spraying was employed for coating deposition. During deposition, the substrate surface was kept at 500°C. The effect of melting degree of spray particles on coating microstructure was investigated by changing the flame power and spray distance. The porosity of flame-sprayed Al2O3 coatings was estimated by image analysis on coating cross-sectional microstructures. The results showed that porous Al2O3 coatings were successfully prepared with a porosity range up to 59% by flame spray. Moreover, spray parameters such as acetylene flow rate and spray distance have significant influences on the particle melting state, thus the microstructure and the porosity of the coating. With the decrease of acetylene flow rate and spray distance, the porosity of coatings increased due to the decrease of the melting degree of the sprayed particles. At a spray distance of 20 mm, when the acetylene flow rate was reduced from 400 to 200 L/h, the porosity increased from 37% to 59%. The results clearly demonstrated the feasibility to prepare porous abradable coatings of high porosity through surface-melted spray particles.
Current and Next-Generation Titanium Blade Compatible Compressor Abradable Coatings
Authors: Sporer D. , Wilson S.
Published: January 2023

Compressor abradables coming into operational contact with bare, un-tipped titanium alloy rotor blades over a wide range of incursion conditions require excellent cuttability in order to avoid blade tip damage by wear and over-heating. This is more easily achieved for low temperature systems that can make use of low shear strength aluminum matrices than for compressor abradables operating closer to the maximum allowable temperature of advanced titanium alloy blade materials. In this case the rotor path linings will have to incorporate higher temperature resistant Ni and Co alloy matrices. To that end the availability of abradable coatings capable of operating at up to 550°C while showing little thermal ageing effects and excellent abradability over their entire service life can influence the compressor blade material selection and therefore compressor weight and performance characteristics. This paper provides an overview of titanium blade friendly compressor abradable concepts. Particular emphasis will be placed on the abradability of in-service and next-generation coatings designed for use up to the temperature capability of Ti blade rotor materials and beyond. Candidate coatings are also screened for other performance criteria such as thermal cyclic resistance and ageing behaviour.
Integrated Study of APS YSZ Coatings with Different Spray Angle
Authors: Chen Y.K. , Tan Y. , Tessarini S. , Sampath S.
Published: January 2023

Spray parameters play an important role on the microstructure and properties of plasma sprayed coatings. Parameters such as spray distance, plasma gas flow and current, raster speed and spray angle all can be varied. In this paper, an integrated study to investigate the effects and influences of spray angle on properties of yttria-stabilized zirconia coatings was carried out with spray angles of 60°, 75° and 90° (to the substrate surface). In situ coating property sensor (ICP) based on beam curvature measurements was used to measure the evolving stress and elastic moduli of the resultant coatings and combined with other characterization tools for thermophysical property and microstructure analysis, such as laser flash and scanning electron microscopy (SEM). The results indicate that the coating with 60° spray angle had the lowest thermal conductivity and more compliant structure. This study seeks to understand the mechanism for this effect and will provide important insight into parametric sensitivities on complex spray parts.
Role of Process Conditions on the Interfacial Fracture Toughness of Plasma Sprayed Zirconia
Authors: Okajima Y. , Nakamura T. , Sampath S.
Published: January 2023

Adhesive strength of the plasma-sprayed thermal barrier coating (TBC) is one of the most important parameters which influence the reliability during service. In the past, numerous test methods were reported to measure the coating adhesion. However, most of them require careful and time consuming preparation. Consequently, limited information could be obtained to establish the relationship between the processing conditions and the adhesive property. To produce more measurements using a simpler procedure, the interfacial indentation test and the modified tensile adhesive test are examined. In this paper, the interfacial fracture toughness of the plasma-sprayed ZrO2 coatings, deposited on Al substrates, were evaluated by these two tests. In order to study the effects of the powder injection, samples were sprayed with various carrier gas flow rates. The test results show a certain correlation between the melting index and the interfacial fracture toughness. In addition, variations between the results obtained from the two different methods are discussed.
High Velocity Suspension Flame Sprayed (HVSFS) Bioactive Coatings for Biomedical Applications
Authors: Stiegler N. , Killinger A. , Gadow R.
Published: January 2023

Thermal spraying of suspensions containing particles of submicron or nano-size offers new possibilities in functional coating development and enables new application fields. Spraying of suspensions containing bioceramic materials by hypersonic flame spraying (HVSFS), result in coatings with a refined microstructure. A layer thickness ranging from 10 - 50 µm can be achieved. Thermally sprayed HAp coatings are widely used for various biomedical applications due to the fact that HAp is a bioactive, osteoconductive material capable of forming a direct and firm biological fixation with surrounding bone tissue. Bioceramic coatings (e.g. Hydroxyapatite HAp, Tricalcium Phosphate TCP or Bioglass) were thermally sprayed on Ti plates by high-velocity suspension flame spraying. The deposited coatings were mechanically characterized. The bond strength of the layer composites was analyzed by the pull-off method and compared for different spraying conditions.
Design of Experiments Analysis of Flame Sprayed PCL/PMMA Bioactive Coatings
Authors: Chebbi A. , Stokes J.
Published: January 2023

Bioactive coatings are proven to enhance bone regeneration, implant integration and act as drug-delivery systems following bone replacement surgeries. Polycaprolactone (PCL) was used in this study as coating material due to its superior biocompatibility and biodegradability. Polymethyl-methacrylate (PMMA) was used as an additive in order to improve the flowability of the PCL powder. The processing technique used to obtain polymeric coatings was oxy-acetylene flame spraying. Seeing that biodegradable polymers were not thoroughly investigated in the past, a Design of Experiments (DoE) analysis was necessary in order to understand the effects of spraying parameters on coating characteristics (thickness, roughness, adhesion, wettability) and to be able to optimize the coating properties for specific requirements. The polymer matrix was sprayed onto titanium substrates. The statistical analysis was followed by FTIR spectroscopy, which showed that the coatings underwent little chemical degradation. Finally, biocompatibility tests showed that cells proliferated well on the flame sprayed polymer coatings, which confirms that the coating technique used did not affect the biological performance of the material.