bluuebunny/crossref_metadata_2025 huggingface dataset:
IceCube Constraints on the Fermi Bubbles
Authors: Sherf Nimrod , Keshet Uri , Gurwich Ilya
Published: September 2017

We analyze the IceCube four-year neutrino data in search of a signal from the Fermi bubbles. No signal is found from the bubbles or from their dense shell, even when taking into account the softer background. This imposes a conservative ξ

i
 < 8% upper limit on the cosmic-ray ion (CRI) acceleration efficiency, and an η ≡ ξ

e
/ξ

i
 ≳ 0.006 lower limit on the electron-to-ion ratio of acceleration efficiencies (at the 2σ confidence level). For typical ξ

i
, a signal should surface once the number of IceCube neutrinos increases by ∼an order of magnitude, unless there is a <PeV cutoff on the CRI spectrum.
Buoyant AGN Bubbles in the Quasi-isothermal Potential of NGC 1399
Authors: Su Yuanyuan , Nulsen Paul E. J. , Kraft Ralph P. , Forman William R. , Jones Christine , Irwin Jimmy A. , Randall Scott W. , Churazov Eugene
Published: September 2017

The Fornax Cluster is a low-mass cool-core galaxy cluster. We present a deep Chandra study of NGC 1399, the central dominant elliptical galaxy of Fornax. The cluster center harbors two symmetric X-ray cavities coincident with a pair of radio lobes fed by two collimated jets along a north–south axis. A temperature map reveals that the active galactic nucleus (AGN) outburst has created a channel filled with cooler gas out to a radius of 10 kpc. The cavities are surrounded by cool bright rims and filaments that may have been lifted from smaller radii by the buoyant bubbles. X-ray imaging suggests a potential ghost bubble of ≳5 kpc diameter to the northwest. We find that the amount of gas lifted by AGN bubbles is comparable to that which would otherwise cool, demonstrating that AGN-driven outflow is effective in offsetting cooling in low-mass clusters. The cluster cooling timescale is

times longer than the dynamical timescale, which is consistent with the lack of cold molecular gas at the cluster center. The X-ray hydrostatic mass is consistent within 10%, with the total mass derived from the optical data. The observed entropy profile rises linearly, following a steeper slope than that observed at the centers of massive clusters; gas shed by stars in NGC 1399 may be incorporated in the hot phase. However, it is far-fetched for supernova-driven outflow to produce and maintain the thermal distribution in NGC 1399, and it is in tension with the metal content in the hot gas.
Technology Education Teachers' Professional Development Review Through Community Engagement
Authors: Mapotse Tome' Awshar
Published: September 2017

It is the supreme art of an action research practitioner to awaken the joy of tapping into professional development review of Technology Education (TE) knowledge with the teachers as co-researchers. TE has been introduced as a new subject nationally and globally just few decades ago. Teachers and learners are still experiencing hurdles in implementing TE. Most teachers are poorly grounded in pedagogy and content knowledge of Technology Education. This AR study does not blame the limited teacher training in TE, as its intention was to empower such. The study was underpinned by critical theory and following the AR strategies and Technology Education Cascading Theory was envisaged to be incorporated. Focus group (interviews) was used as the method to engage these TE teachers. From the findings of the study, it has been proven that the AR approach study can be used in didactic and pedagogic situation to emancipate unqualified and under qualified Technology teachers.
Teacher Learning and Effective Professional Development
Authors: Mehorter Bronwyn
Published: September 2017

Action Learning has been and is regularly implemented within Australian schools as a platform for teacher professional development and professional learning. The following chapter reports on a decade-long association between one Australian government primary school, an Academic Partner and the process of Action Learning. Initially, Action Learning was implemented in 2005 in the form of a small-scale, more traditional Action Learning project; In 2009, Action Learning was then modified and stretched to involve the whole school's teaching, support and executive staff; In 2013, the principles of Action Learning were extended as the school executive and teaching staff began to take ownership over their own learning. This case study demonstrates that Action Learning can be implemented on a school-wide basis for the effective professional development of the whole school's teaching and executive staff. Recommendations are made for similar schools who are considering extending Action Learning across the whole school.
Action Research Driving a Scaffolded Soil Science Curriculum
Authors: Milaras Milton , McKay Tracey
Published: September 2017

A case study of a Soil Science teaching intervention for second year university students is presented here. The purpose was to address post-first year student underpreparedness for higher education. The curriculum was redesigned to iteratively develop students' academic writing skills: with particular regard to environmental report writing, whilst imparting Soil Science content. To this end, students had to integrate practical and theoretical learnings into a soil erosion modelling report. ‘Micro action research dialogues' were used to drive the development and delivery of this scaffolded curriculum. Both the process of curriculum development, and the curriculum itself, are detailed here. Recommendations were arrived at by the means of action research reflection: primarily, academics should engage formally with education as a discipline if curricula are to be successfully redesigned. Secondary recommendations are: a deep approach to learning requires a less dense curriculum; tutors need to be more formally capacitated; and administrative hurdles should not be underestimated.
Developing a Reflexive Teaching Model
Authors: Shambaugh Neal
Published: September 2017

A reflexive teaching model, which has both instructor and students examine their learning beliefs and teaching decisions during a course, has been used for 23 years in the teaching of a graduate instructional design course. Teaching model development is reported across four time periods. During Period 1 (1994-1999) the model was studied in a five-year case study using design and development research and is summarized using the Models of Teaching framework (Joyce, Weil, & Calhoun, 2014). Period 2 (1999-2001) reports the use of scenarios to test out new participation structures within the model. Period 3 (2001-2006) documents how the model was used in blended deliveries. Period 4 (2007-2016) summarizes changes in teaching procedures and participation when the course was delivered totally online. The chapter concludes with comments on developing a teaching model and a longitudinal agenda for studying one's teaching.
Questioning the Role of Tomorrow's Teacher
Authors: Reid Doug , Feist David
Published: September 2017

A technology diverse school explored a shift toward more student centered pedagogical practice. The project happened to determine if a shift in teacher practice could impact student engagement and success. The results were positive as many students had more academic success when student-centered learning activities were incorporated into their schooling. In theory, this means student learning theory including non-linear learning approaches can work in more generalizable settings than have been deeply published in the current literature. In practice, the findings may help to inform schools dealing with current societal pressures to help their students find greater success through the use of pedagogically appropriate technology implementations and teacher support.
Technology Integration Models for Digital Equity
Authors: Mysore Anita Rao
Published: September 2017

The purpose of this chapter is to examine the empirical reviews and studies on technology integration models in teacher education programs with a view to bring about digital equity. The chapter informs teacher education programs, researchers, and other stakeholders about evidences and recommendations on research on technology integration models.
Designing Curricular Games
Authors: Kellinger Janna Jackson
Published: September 2017

Most teachers only dream of their students spending the amount of motivation, attention, passion, and critical thinking on their classes that some do playing video games. Many teachers have thought “How can I compete with that?” as they confiscate a hand-held gaming device from a student. However, more and more teachers are incorporating video games into their curriculum, instead of banning them. This chapter argues that it is not just video games that can transform teaching, video game techniques can as well. By using video game design principles such as game stories and quests, teachers can restructure their teaching so students do not just learn the curriculum, they experience it. This chapter explores the research on using game-based teaching and learning with the Next Generation including how game-based teaching can be used to achieve 21st century goals as outlined by business leaders within 21st century educational constraints.
Collective Intelligence in Online Education
Authors: Farmer Lesley S. J.
Published: September 2017

Collective intelligence may be loosely defined as the capacity of a group to think, learn, and create collectively. Online education reflects an interactive mode relative to information, particularly because of social media, that can involve expertise and resources that generate collective intelligence to address issues. Several theories reflect a belief in the dynamic and situational meanings that collectives create. The impact of technology, particularly in terms of social networks, also informs collective intelligence-related educational theories. This chapter explains conditions for optimum use of collective intelligence, noting individual and group behaviors, cultural factors, and its application in online education.
Comparing Teacher Experiences Using a Learning Management System in K-12 Schools in Saudi Arabia
Authors: Alahmari Ayshah , Kyei-Blankson Lydia
Published: September 2017

Since the school year of 2014-2015, the learning management system, Classera, has been implemented in many K-12 schools in Saudi Arabia with the aim of improving teaching and learning. In this study, an online survey was used to collect data to explore Saudi Arabia private and public school teacher differences in experiences with the use of Classera, and their satisfaction levels, perceived benefits, and perceived challenges in using Classera. The findings from this study have implications for the further implementation and adoption of Classera in the educational system in Saudi Arabia.
Assessing the Maturity of Green IT Adoption Within the Philippine Manufacturing Industry
Authors: Hernandez Alexander A.
Published: September 2017

Green IT is the sustainable use of computing resources in organizations with minimal or no impact on the environment. The role of Green IT is recognized to achieve sustainability in organizations. This study presents the extent of Green IT adoption in a developing country. This study used GIT maturity model to assess the overall level of Green IT maturity among manufacturing organizations. The results suggest that participants recognized Green IT, however, a low level of maturity is found within the manufacturing organizations. To further Green IT adoption in organizations, practical and research implications are presented.
REPRESENTAÇÕES SOCIAIS DE CORPO APÓS O ADOECIMENTO POR CÂNCER NA PRÓSTATA
Authors: Martins Alberto Mesaque , Nascimento Adriano Roberto Afonso do
Published: September 2017

O estudo tem como objetivo identificar e analisar as Representações Sociais de corpo para homens após o adoecimento por câncer na próstata. Foram realizadas entrevistas narrativas com oito homens com idade entre 50 e 70 anos, diagnosticados com câncer na próstata e que realizaram tratamento oncológico há pelo menos um ano. As entrevistas foram gravadas, transcritas e analisadas por meio da Abordagem Fenomenológica Interpretativa. Os resultados apontam que antes do adoecimento, os participantes representavam seus corpos como fortes, resistentes e saudáveis, tendo no modelo de masculinidade hegemônica um importante ponto de ancoragem para estas representações. A ausência de sintomas que provocassem desconfortos corporais contribuiu para a percepção de corpo saudável. A busca por serviços de saúde somente ocorreu após a manifestação e agravamentos dos primeiros sintomas, que limitaram suas ações diárias e alteraram o seu cotidiano. O adoecimento por câncer na próstata e as propostas de tratamento oncológico, em especial, a prostatectomia, foram destacados pelos participantes como uma experiência marcante e produtora de grande desconforto físico e psicológico. Após o adoecimento, os homens passaram a representar os seus corpos como frágeis, doentes e debilitados. Os entrevistados chamam a atenção para o impacto das transformações corporais, especialmente aquelas relacionadas às disfunções sexuais e urológicas, nos modos de pensar, sentir e agir, em relação à própria masculinidade. Nesse sentido, as limitações impostas pelo adoecimento e tratamento oncológico se contrapõem ao modelo de masculinidade hegemônica, favorecendo o sentimento de ser menos homem do que antes do adoecimento.
A EPISTEMOLOGIA DO PENSAMENTO SISTÊMICO E AS CONTRIBUIÇÕES DE HUMBERTO MATURANA
Authors: Oliveira Joyce Lúcia Abreu Pereira , Crepaldi Maria Aparecida
Published: September 2017

ResumoA epistemologia do Pensamento Sistêmico (PS) passou por importantes transformações ao longo do século XX e, progressivamente, ganha espaço nas investigações científicas e intervenções em diferentes contextos. Compreender seus princípios epistemológicos tem sido um desafio em cursos de graduação e pós-graduação de diferentes áreas, sendo condição sine qua non na produção de pesquisas e intervenções sistêmicas. Desse modo, este artigo tem por objetivo apresentar o desenvolvimento histórico e epistemológico do PS no século XX e as contribuições de Humberto Maturana para o avanço da ciência pós-moderna. Apresenta-se a mudança paradigmática da ciência tradicional para a ciência pós-moderna, bem como os pressupostos básicos que as caracterizam. Propõe-se o uso de uma espiral histórica e epistemológica, além do conceito de recursividade, para facilitar a compreensão das interconexões entre pesquisadores e teorias que contribuíram para o desenvolvimento do PS no século XX. São apresentados os principais conceitos de teorias sistêmicas com reconhecimento e visibilidade na comunidade científica, quais sejam, a Teoria Geral dos Sistemas, a Cibernética, a Teoria da Comunicação. Conclui-se que a epistemologia do PS tem possibilitado avanços significativos para a ciência, ao considerar de forma integrada os pressupostos epistemológicos da complexidade, da instabilidade e da intersubjetividade na análise dos fenômenos, em pesquisas e intervenções em diferentes contextos.Palavras-chave: Pensamento pós-moderno, Epistemologia; Intersubjetividade.
OFICINA COM ADOLESCENTES DO MST: PRECONCEITO E CONVIVÊNCIA COLETIVA
Authors: Domingues Eliane , Liboni Maria Therezinha Loddi , Toporowicz Aline , Bazzotti Deborah Sartório , De Melo Débora De Nez , Dos Santos Georgia Lara , Matsuda Luciana Lika
Published: September 2017

Apesar de todas as conquistas dos movimentos sociais no que se refere à educação do campo, as crianças e jovens do Movimento dos Trabalhadores Rurais Sem-Terra (MST) vivenciam situações de preconceito por sua pertença, quando estudam em escolas não vinculadas ao movimento, vivencias que os marcam profundamente. O preconceito pela pertença ao MST que vem a se somar a diversos outros, foi o tema demandado para ser trabalhado em nosso projeto de extensão, realizado em uma escola técnica de agroecologia fruto de uma parceria entre o MST e o Instituto Federal Tecnológico do Paraná (ITFPR). Os participantes do projeto foram adolescentes e jovens, com idades que variam entre 15 e 24 anos, sete são do sexo feminino e os demais do sexo masculino, todos oriundos de acampamentos e assentamentos da reforma agrária. A metodologia adotada no trabalho foi a realização de oficinas com o tema principal “preconceito e convivência coletiva” e os seguintes temas geradores: possibilidades e limites frente às diferenças, preconceito e empatia, empatia e comunicação, preconceito racial e bullying. Foram realizados oito encontros semanais, com duração de 2 h. Concluímos que a metodologia das oficinas se mostrou efetiva ao ir além dos aspectos educativos/informativos, abarcando e trabalhando com os significados afetivos, os sentimentos e as vivências, proporcionando espaço para a fala, a reflexão e a elaboração, tanto individual como coletiva. Além de potencializar o contexto favorável a formação humana que o MST construiu ao longo da sua existência.Palavras-chave: Oficina; adolescentes, MST.
Influence of Process Parameters on Geometric Precision of Machined Surface after WEDM
Authors: Straka Ľuboslav , Hašová Slavomíra
Published: September 2017

Geometrical precision machined surface is generally understood as mainly precision shape, orientation, location and run-out. As a rule, it is measuring the appropriate deviations from the nominal surface. The geometric size of this deviation from the nominal surface can in practice affect the conventionally measured value for the dimension and the dimension whilst maintaining the required tolerance. Because the WEDM technology is among the most accurate technology, the small final geometric accuracy deviation has also a negative impact on the final quality of the machined surface. The paper aimed to describe errors geometrical precision of machined surface which occurs in wire electrical discharge machining (WEDM) and quantify their scope.
Measuring the Size of Vibrations on a Mill Using the Vibration Analysis
Authors: Olejárová Štefánia , Krenický Tibor
Published: September 2017

When processing materials using the milling technology, regenerative fluctuations of vibrations are the decisive factors, which limit productivity. In some case the size of the vibrations can cause shortened lifespan of the tool, decrease reliability and operational condition of the device, and subsequently case poor quality of the processed surface. Predicting the size of the vibrations between the milling machine and the work-piece is important as a lead for the users of the tool to select optimum depth of the cut and turning of the spindle, which leads to maximum rate of splinter removal. The extent of the research is focused especially on the process of monitoring, with the goal to analyze the size of the vibration at three places determined in advance - spindle head, work-piece and support, where rotation speed of the spindle change during the processing, as well as rate of splinter removal. By evaluating the results of experimental research, it is possible to determine adequate rotation speed of the spindle and depth of the cut, to achieve longest lifespan of the machine.
Dynamics of a Moulding Cooling at Injection of Plastics
Authors: Ružbarský Juraj
Published: September 2017

For a regulation of moulding cooling time course in a mould it is necessary to derive an equation of the mould temperature dependence on the moulding temperature as the equation of the regulation system. Amplitude, phase and transition characteristic are for R=1 and P=1 identical as for the action quantity. Amplitude, phase and transition characteristic of the action quantity and the control of the regulation circuit at use of the proportional regulator show that the circuit is stable a periodic. From the amplitude, phase and transition characteristic of the regulation circuit defect it is seen that the defect in the regulation circuit is relatively fast lowered.
From the mentioned conclusions it is seen that the moulding cooling in the mould at injection of plastics with the proportional regulator introduces the regulation with relatively favourable regulation properties.
Analysis of the Mechanical Properties Change of PA6/MMT Nanocomposite System after Ageing
Authors: Dulebová Ľudmila , Greškovič František , Sikora Janusz W. , Krasinskyi Volodymyr
Published: September 2017

The paper deals with the influence of environmental degradation on the change of the mechanical properties of polymer nanocomposites. The tested material was polyamide (PA) filled with nanoclay fillers Cloisite 30B, Cloisite 93A and Cloisite Na + in a volume of 2, 4 and 6 wt%. Test samples were produced by injection molding and were subjected to 540 hours and 1080 hours of UV radiation. The change of mechanical properties of PA6/MMT nanocomposite systems after the ageing in the UV chamber was studied by tensile test and Charpy impact resistance test. Article also compares structure of PA6/MMT nanocomposite.
Application of Technical Elements of the Liquid Crystal in the Area of Manufacturing Operations
Authors: Krehel' Radoslav , Kočiško Marek
Published: September 2017

The article describes application of using liquid crystals in area of contactless scanning. Concrete application is showed in a turning process oriented to controlling and direction. Polarising attributes of liquid crystals is used in integration of exactness and sesitivity of electrostatical scanning principe and stability and simplicity of optical scanning, whole system has a higher resistance to an exterior disturbing actions and resistance to a possible electrostatical discharge. The article describes a consecution and conditions of practical measuring of principe ́s attestation, elaboration and interpretation of measuring answer.
Experimental Determination of the Focal Length of a Laser Beam from the Output Nozzle of a Laser Cutting Head
Authors: Lachman Martin , Šafka Jiří
Published: September 2017

Laser technologies are considered to be unconventional technologies. Laser cutting is one of the most popular industrial operations that use a laser beam. Fibre lasers are most commonly used for cutting metallic materials. The aim of this paper is to experimentally demonstrate a procedure for determining the focal length of a laser beam from the output of the cutting head of a JK400FL fibre laser. Along with other factors, the correct position of the focal point of a laser beam cutting materials, plays a vital role in the quality of the cut and also in determining the cutting speed. It is possible to use a higher cutting speed of the laser machine, without compromising the quality of the cut.
Sophisticated Production from Organic PLA Materials Processed Horizontally by Fused Deposition Modeling Method
Authors: Nováková-Marcinčinová Ema , Panda Anton , Nováková-Marcinčinová Ľudmila
Published: September 2017

The article focuses on the samples production of organic material PLA-PolyLacticAcid – bioplastic. The main part describes the experimental testing of PolyLacticAcid plastic and sample production by Fused Deposition Modeling, Rapid Prototyping technology. The article presents selected carried out tests of mechanical properties focused mainly on the determination of ultimate tensile strength of two PLA-BIO plastic extruded horizontally along the width produced by FDM method, Rapid Prototyping. The authors of this article present their results of test materials in the form of measurement protocols recorded in software, the measured values in a static tensile test, recorded in tables and shown in work graphs. Based on the results of the two samples produced from PLA biomaterials and compared to determine which PLA – bioplastic is stronger.
Possible Causes in Breaking of Dental Implants Research
Authors: Stoicănescu Maria , Buzamet Eliza , Budei Dragos Vladimir , Craciun Valentin , Budei Roxana , Cosnita Mihaela , Crisan Aurel
Published: September 2017

Dental implants are becoming increasingly used in current dental practice. This increased demand has motivated manufacturers to develop varieties of product through design, but also looking for new materials used to improve surface characteristics in order to obtain a better osseointegration. But the increase in the use of implants goes to a consequent increase in the number of failures. These failures are caused either by treatment complications (peri-implantitis), by fatigue breakage under mechanical over-stress, by defective raw material, or due to errors during the insertion procedures. Although they are rare, these complications are serious in dentistry. Before to market a dental implant to clinical practitioners, the product is validated among other determinations in number of biocompatibility research. Raw material issues, details about its structure and properties are less published by the scientific literature, but all this are subject of a carefully analysis of the producers. Breaking of dental implants during surgical procedures, during the prosthetic procedures or during use (chewing, bruxism, accidents, etc.), is the second most common cause of loss of an implant after consecutive peri-implantitis rejection. Although the frequency of this type of failure for a dental implant is much smaller than those caused by the peri-implantitis, a detailed study of broken implants can explain possible causes. The use of scanning electron microscopy (SEM) in the study of the cleave areas explain the production mechanism of cleavages, starting from micro-fissures in the alloy used for the production of dental implants. These micro-fissures in weak areas of the implant (anti-rotational corners of the polygons, etc.) could generate a serious risk of cleavage first time when a higher force is applied.
Tribological Behavior of Distaloy DC Components
Authors: Öksüz K. Emre , Akınalp Yusuf Alper , Kumruoğlu Levent Cenk
Published: September 2017

A sintered material based on pre-alloyed powders (Fe-Ni-Mo) is expansively applied in the automotive industry and Distaloy is today the most widely used raw material worldwide for the production of complex, precise, high strength PM machine parts. In this study a diffusion bonded powder type of Distaloy DC (Fe-2 wt. % Ni-1.5 wt. % Mo, Höganäs-Sweden) was used. It was alloyed by 0.5 and 1 wt. % silicon carbide with the addition of 0.6 wt. % lubricant in the form of introlube®. All the powder mixtures were compacted at 600 MPa, and then sintered for 30 min. in argon atmosphere at 1120° C. After the completed sintering process, the sintered alloy samples were gas-nitrided 1h at 490 °C and 6h at 540 °C, respectively, and cooled slowly to room temperature still under the ammonia atmosphere. The effects of varied amounts of SiC particles on the tribological behavior of nitrided-sintered Distaloy DC composites were investigated.
Adhesion Characterisation of Complex Ceramics Thin Layers Deposited on Metallic Substrate
Authors: Florea Costel , Bejinariu Costică , Savin Cristian , Istrate Bogdan , Benchea Marcelin , Cimpoeşu Ramona
Published: September 2017

There was obtained superficial layer of ceramic (made of complex oxides 80% yttrium oxide stabilized zirconium ZrO2/8%Y2O3 (Metco 204B-NS) and 20% alumina Al2O3 (Metco 105SFP)) by plasma jet deposition at a temperature of 12000°C of particles, on substrates of iron FC250. The layers were obtained by five successive passages (60 μm thick) on samples with different surface roughness and different processed (0.34, 2.47 și 4.25 μm). For the analysis of the adhesion of ceramic layers to the substrate scratch tests were carried out and the traces analyzed by scanning electron microscopy (SEM 2D and 3D), chemical analysis EDS, and profilometry. In conclusion, it was obtained compact layers on the samples 2 and 3 with micro-cracks on the surface due to thermal gradient that occurs between the layers deposited during the five passes. Regarding the resistance, the sample with the higher roughness (sample 3) resisted most to exfoliation the layer (15 N) in contrast to the sample 2 of 14N and only 10N for the polished sample. It can be concluded that there is a dependency between the surface roughness and the thickness of layer deposited. Scratch marks presents no cracks, pores or adjacent exfoliation. The results show that the technique is suitable for obtaining thin layers of ceramic materials with a very good control of the thickness, very good adhesion to the substrate and a direct relationship between surface roughness and the quality of deposited layer.
Coating of Liquid Wood Sheets
Authors: Mocănița Ovidiu , Chicet Daniela Lucia , Benchea Marcelin , Istrate Bogdan , Munteanu Corneliu
Published: September 2017

Liquid wood is one of the newly discovered green polymer materials, being a biodegradable and recyclable thermoplastic, made from cellulose, lignin and natural additives, currently used in commerce as ARBOFIL, ARBOROM and ARBOBLEND. The applications of this material (aeronautics, automotive, construction, consumer goods etc.) are limited by two major drawbacks: higher weight compared to ordinary plastic materials and low melting point (≈ 175° C).
In this work was studied the possibility of changing some mechanical and thermal properties of this material by applying superficial coatings. For this process were prepared specimens from two types of material: ARBOBLEND and ARBOFIL. The resulted samples were analyzed in terms of microstructural changes both longitudinally (in order to evaluate the quality of the deposited layer) and on cross section (in order to evaluate the changes produced at the interface substrate - coating). For this purpose were used the QUANTA 200 3D (FEI, Holland, 2009) scanning electron microscope and the X`PERT PROMD diffractometer (Panalitycal, Holland, 2009). Using the UMTR 2M-CTR Micro-tribometer were evaluated the elasticity modulus of the coatings through microindentation and its adhesion to the substrate through scratch method, applied both longitudinally and on cross section.
Abnormal Behavior of Lattice Spacing of Titanium Orthorhombic Martensite
Authors: Demakov Sergey , Semkina Iana , Stepanov Stepan I.
Published: September 2017

Samples of VT23 β-metastable titanium alloy quenched from temperatures in a range between critical and β-transus were studied in situ during heating on X-ray diffractometer. The anisotropy of orthorhombic martensite lattice was investigated. Abnormal behavior of «b» lattice spacing, which demonstrated a negative value of thermal expansion, has been revealed.
Cold End Corrosion Avoiding by Using a New Type of Air Combustion Pre-Heater
Authors: Enescu Maria Cristiana , Vlădulescu C. Marius , Gaba Aurel , Bratu Vasile , Stoian Elena Valentina , Petre Ivona Camelia
Published: September 2017

This paper analyzes the possibility of reducing the cold end corrosion in boilers and furnaces by using a new type of air combustion pre-heater. Cold end corrosion appears due to catalytic oxidation of the sulfur dioxide to sulfur trioxide and then due to the sulfuric acid condensation at dew point. Calculating dew points of various acid gases and options for reducing cold end corrosion of heat recovery exchangers are presented. For avoiding the cold end corrosion we design a new type of air combustion pre-heater for boilers and furnaces. Also, the tube skin temperature of the first row of pipes of the actual air pre-heater was simulated with this computer program, in order to determine whether this temperature is lower than acid dew point of flue gas. With the simulation for this configuration of the actual combustion air pre-heater, the skin temperature for the first row (for the combustion air flow) of tubes from the upper bundle was TS = 134 °C. A way to reduce the cold end corrosion in the combustion air pre-heaters is raising the temperature of the combustion air at the air pre-heater entrance. This solution involves taking a quantity of preheated air, recirculation and then reintroducing it in the air pre-heater. In the same time, this solution avoiding to use the steam radiator, mounted after the fan, for pre-heating the combustion air from 1°C to 45°C. Thus, the furnaces equipped with the new combustion air pre-heater and modern low NOx burners made a fuel economy about 3%.
Effect of Strain Hardening on Precipitation Kinetics in ATI 718Plus
Authors: Hassan Bilal , Jansen Yann , Nouveau Sebastien , Corney Jonathan
Published: September 2017

ATI 718Plus components are manufactured by forging a wrought billet in stages to obtain the desired geometry and microstructure. Parts are then heat treated to optimized proportions of γ’ and η phases. η phase is a plate-like phase that precipitates on the grain boundaries of ATI 718Plus, similar to δ phase in Inconel 718. However, the complete kinetic behaviour of η phase precipitation during forging and heat treatment is still not fully understood. This paper investigates the effects of strain hardening on η phase precipitation kinetics in ATI 718Plus. This is achieved through the use of isothermal hot compression tests and heat treatment. Strain hardening was found to affect the η precipitation kinetics considerably. The results reported are a contribution to a fuller understanding of this important process
Relationship between Deformation and Recrystallization Texture in Copper Wire
Authors: Zorina Maria , Stepanov Stepan I. , Karabanalov Maxim , Lobanov Mikhail L.
Published: September 2017

Using electron backscatter diffraction (EBSD), the relationship between deformation textures, developed upon different stress-strain states and characterized by the basic crystallographic orientations of recrystallized grains, has been studied in a FCC metal. The regularities of recrystallization twins development were considered. Crystallo-geometric relations between the deformation and the recrystallization orientations were explained with the mobility of the special grain boundary close to the coinciding site lattice boundary Σ25b. Mechanisms of nucleation and growth of the annealing twins were proposed.
Hot Working Effects on the Damping Behavior of Shape Memory Alloys
Authors: Popa Mihai , Pricop Bogdan , Mihalache Elena , Bujoreanu Leandru Gheorghe , Lohan Nicoleta Monica
Published: September 2017

Cu-Zn-Al shape memory alloys (SMAs) were analysed in two different processing states: (i) hot-forged and (ii) hot-rolled. Both hot-forged and hot-rolled specimens were cut into lamellar configuration, before being homogenized (1073 K/ 18 ks/ water) and tempered (373, 473, 573, 673 K/ 300 s/ water). From each of the five differently treated lamellas, in hot-forged and hot-rolled states, rectangular specimens were cut for dynamic mechanical analysis (DMA). The remaining segments were sectioned into metallographic specimens. The metallographic specimens were embedded into could mounting resin, ground, polished and etched for scanning electron microscopy (SEM) -observations. DMA results revealed the influence of plastic deformation procedure and heat treatment temperature on the reversible martensitic transformation.
Thixoforming and Powder Metallurgy - A Comparative Study and Practical Case
Authors: Gallego Parra Samuel , Pop Mihai Alin , Bedő Tibor , Geamăn Virgil
Published: September 2017

Pistons are commonly made of a cast aluminum alloy for excellent and lightweight thermal conductivity. Thermal conductivity is the ability of a material to conduct and transfer heat. Aluminum expands when heated and proper clearance must be provided to maintain free piston movement in the cylinder bore. The piston transforms chemical energy of the burned fuel into a mechanical energy. For this reason, the pistons are submitted to a complex combination of thermal stresses and high temperature mechanical cycles. In this study both powder metallurgy (PM) and thixoforming techniques are used to process a metallic matrix composite (MMC) as a promising material for pistons. Aluminum as matrix and copper powder, to enhance thermal conductivity, and glass fiber, which increases Young’s modulus and a lower thermal expansion coefficient, as reinforcement, are obtained for this aim. The optical microscope images showed in this study are a clear example of the distribution of the glass fiber in the matrix. These results can be the basis for new researches to develop and to obtain materials for new advanced materials for pistons.
Mechanical Properties and Microstructure Aspects of AlSi10Mg Casting in Vibrating Field
Authors: Tierean Mircea Horia , Baltes Liana Sanda , Banea Alexandru Stefan
Published: September 2017

Aluminum alloys are one of the most extended groups of functional materials by reason of combination between good mechanical properties and low mass. The aim of the present paper is to test the influence of the vibrations on the AlSi10Mg (EN 1706-2010) solidification. For comparison, six lots were casted in cold and preheating molds, with or without vibrations within 50 Hz and 1050 Hz. For each casting frequency was measured the silicon phase dimension, hardness, tensile stress and impact strength. The mechanical properties increase with the vibration frequency. Increasing the vibration frequency, the structure will be refined and also the size of the silicon phase is decreasing. Considering that one source of porosity is the gas entrapped or dissolved in the liquid metal during the casting, using vibration along casting and cooling allows it’s decreasing.
Induction Brazing of Copper Parts Using Amorphous Brazing Alloys
Authors: Codrean Cosmin , Buzdugan Dragoş , Radu Bogdan , Şerban Viorel Aurel
Published: September 2017

Brazing alloys with amorphous structure have excellent technological properties (tensile, wetting), having a self-fluxing character. The brazed joints have good mechanical and corrosion resistance. In this work an amorphous alloy, ribbon form, for brazing of copper pipe components, was elaborated. The brazed joints were analyzed by optical and electronic microscopy. The brazing alloy is self-fluxing and has good tensile and wetting properties. The structure in the brazed joint is monophasic due to the optimization of the process parameters (voltage and brazing time).
Dielectric Properties of Sr-Doped BaZrO3 Ceramics
Authors: Torman Merve , Öksüz K. Emre , Şen Şaduman , Şen Uğur
Published: September 2017

Perovskite compounds have received keen interest from academic research due to their unique properties such as ferroelectric, pyroelectric, piezoelectric, and dielectric properties. Nano sized oxides of strontium doped barium zirconate of general formula Ba1-xSrxZrO3 (x= 0.2, 0.4, 0.6, 0.8) have been prepared by a solid-state procedure. The surface morphology, microstructure, and phase analysis, of the sintered ceramics were characterized by field emission scanning electron microscopy (FE-SEM). Scanning electron microscopic studies showed the formation of cubic and hexagonal nanoparticles with an average grain size of 1.6μm±0.47 and 0.82±0.35μm. Dielectric studies were carried out as a function of frequency to explore the electrical properties of Sr-doped BaZrO3.
Thermal Processing of a Titanium Alloy for Aeronautical Applications
Authors: Achiței Dragoș Cristian , Vizureanu Petrică , Minciună Mirabela Georgiana , Al Bakri Abdullah Mohd Mustafa , Sandu Andrei Victor
Published: September 2017

The titanium alloys are used in aeronautical applications (up to 75% of titanium alloys), reinforcements, biomedical applications, army industry, because of a high traction resistance, low weight, excellent corrosion resistance and capacity to resist at extreme temperatures. However, some titanium applications are restricted by the small hardness, high friction coefficient and low usage resistance. The paper shows the experimental researches made on Ti-6Al-4V alloy, subjected to quenching and tempering heat treatments. The hardening heat treatment of titanium alloys with α+β structure consists in stabilization phenomenon of β solid solution dissolved in α’ and α’’ metastable phase. After quenching and tempering heat treatments, are obtained good mechanical properties in biphasic alloys, maintaining the plasticity characteristics in reasonable limits. The efficiency evaluation of heat treatments was realized through micro-hardness measurement and structure analyses on electronic microscope.
Characterization of the Surfaces Obtained by Gouging
Authors: Fazakas Barna , Machedon-Pisu Teodor , Cimpoeşu Nicanor
Published: September 2017

In this scientific research we want to present the influence of the gouging process on the basic material and the characterization of the surfaces obtained by different gouging processes. During the experimental researches we used as basic material a structural steel with low level of carbon. The gouging procedures used during the experiment are: arc-air (ArcAirGouging), coated electrode (ManualMetalArcGouging), manual with plasma (PlasmaManualGouging) and mechanized with plasma (Plasma Mechanized Gouging). These processes are classified by a number of processes according to the European standard EN ISO 4063:2009. After the gouging process was finished we measured the roughness of the surfaces. During the gouging process was measured the micro particles concentration with MicroDust 880mm detector. The results obtained after the gouging operation were analyzed with a scanning electronic microscope in order to characterize the grooves’ surfaces. To characterize the gouged surfaces we used a scanning electronic microscope type VegaTescan LMH II, which is equipped with a dispersive X-ray analysis system.
Increasing the Quality of Welded Joints of Al-Si 6082 Alloys by Introducing Forced Vibrations
Authors: Bodeanu Mihai Alexandru , Machedon-Pisu Teodor
Published: September 2017

The solidification process of aluminum alloys welded area has a major influence on the quality of the joining material. Based on this fact, the introduction of forced vibrations during welding aims to prevent the formation of increase tensions inside the welded structure and diminish the presence of pinholes or pores as a result of material contraction of alloys containing metals with a different melting point / solidification point.To avoid this happening it is essential to know and control how the melted material is evolving during the solidification. This step requires that the Al-Si alloy to be welded on a surface with longitudinal vibration composed of a platform whose support can be controlled depending on the required frequency and un M.I.G welding equipment with mechanized welding torch setup to weld, the test peace, above the platform surface. Welding in a mechanical forced vibration environment, results in the formation of a more uniform and finer grain size microstructure with a more advanced diffusion in the affected zone. The diffusion process occurs faster resulting in decreased structural tensions. The presence of voids and pores inside the material structure is inferior for the oscillating welding process in comparison with the classic solution.
Tensile Stress-Induced Structural Changes Associated with Martensite Transformations in Fe-Mn-Si Based Shape Memory Alloys
Authors: Mocanu Mihai , Mihalache Elena , Comăneci Radu-Ioachim , Pricop Bogdan , Özkal Burak , Bujoreanu Leandru Gheorghe
Published: September 2017

Tensile specimens, with the chemical composition Fe-28Mn-6Si-5Cr (mass. %), were obtained by ingot metallurgy, hot rolling, solution treatment (1100°C/ 5 min/ water) and spark erosion cutting. Tensile tests were performed to failure and to prescribed strains, by loading-unloading. Ultimate strain and strength increased up to 80.8 % and 1033 MPa, respectively, with decreasing the cross section of specimens’ gauge down to 2 mm2. The specimens were pre-strained by static tensile loading-unloading tests, to permanent strains as high as 60 %. This procedure aimed to stress-induce martensite, which was further analyzed, on the gauges of pre-strained specimens, by optical and scanning electron microscopy (SEM) as well as X-ray diffraction (XRD). Thermally induced reversion to austenite, of stress-induced martensite, was emphasized, during heating, by differential scanning calorimetry (DSC).
Effect of SiC Particle Size on the Physical and Mechanical Properties of NiTi Alloys
Authors: Akkan Hülya , Şi̇mşi̇r Mehmet , Öksüz K. Emre
Published: September 2017

NiTi shape memory alloys have attracted significant interest due to their unique superelasticity and high damping performance. In this work, the effect of SiC particle size on both physical and mechanical properties of NiTi matrix composite was investigated. Ni and Ti powders with particle sizes of 40 µm were used with the SiC addition with varying particle sizes of 20 µm and 40 µm, respectively. Composites of NiTi with 1wt. % SiC were fabricated by powder metallurgy technique. The effects of SiCp addition on hardness, relative density and wear behavior of NiTi composites have been investigated. The samples were examined by scanning electron microscope, for microstructural studies and phase development. The results showed that the distribution of the reinforced particle was uniform. Moreover, as the SiC particle size decreases, hardness and wear resistance increase. It was demonstrated that SiC particle size significantly enhanced the wear resistance of NiTi composite.
Phase Composition Influence on Melt Viscosity and Ingot Structure Formation Features in EK77 Alloy
Authors: Zhilyakov Arkadiy Yu. , Belikov Sergey V. , Gudov Alexander G. , Burmasov Sergey P.
Published: September 2017

Effect of the alloy initial structure before remelting on the melt viscosity, its state prior to crystallization, and on processes occurring in the alloy in solid state during its subsequent treatment was investigated using EK77 alloy. The study was performed by means of torsional oscillation of the melt with crucible, scanning electron microscopy, and optical metallography.
Estimating Volume Fractions of Microstructural Constituents in Austempered High Silicon Alloyed GJS 600-10 Ductile Iron through Magnetic Measurements (VSM)
Authors: Yürektürk Yakup , Baydogan Murat
Published: September 2017

In this paper, austempering heat treatment was applied to a new generation high silicon GJS 600-10 grade ductile iron with an initial ferritic matrix. Different austempering temperatures of 270, 330 and 390°C were applied after austenitizing at 975°C for 120 min. Depending on the austempering temperatures, lower and upper ausferritic microstructures were obtained. Results showed that volume fraction of the retained austenite in the ausferritic microstructures, which was estimated by VSM technique is well correlated with those estimated by XRD technique.
Thermal and Thermorheologic Characterization of Different Polyolefin Waste Fractions
Authors: Lazar Adela , Croitoru Catalin , Tierean Mircea Horia , Baltes Liana Sanda
Published: September 2017

In this study, melt flow index values from several household waste fractions containing mainly polypropylene and high-density polyethylene, were measured at 190 °C for polyethylene and 230 °C for polypropylene-rich fractions. High values of MFI (low shear viscosities) have been reported probably due to the lower molecular mass of the polymer waste and/or the presence of surfactant compounds on the surface of the polymer flakes. Also, by extruding the same batch in different cycles at the same temperature values, the number of processing cycles on which the polymer could be recycled has been determined.