bluuebunny/crossref_metadata_2025 huggingface dataset:
Ionized Gas Outflows in Infrared-bright Dust-obscured Galaxies Selected with WISE and SDSS
Authors: Toba Yoshiki , Bae Hyun-Jin , Nagao Tohru , Woo Jong-Hak , Wang Wei-Hao , Wagner Alexander Y. , Sun Ai-Lei , Chang Yu-Yen
Published: November 2017

We present the ionized gas properties of infrared (IR)-bright dust-obscured galaxies (DOGs) that show an extreme optical/IR color,

, selected with the Sloan Digital Sky Survey (SDSS) and Wide-field Infrared Survey Explorer (WISE). For 36 IR-bright DOGs that show [O iii]λ5007 emission in the SDSS spectra, we performed a detailed spectral analysis to investigate their ionized gas properties. In particular, we measured the velocity offset (the velocity with respect to the systemic velocity measured from the stellar absorption lines) and the velocity dispersion of the [O iii] line. We found that the derived velocity offset and dispersion of most IR-bright DOGs are larger than those of Seyfert 2 galaxies (Sy2s) at

, meaning that the IR-bright DOGs show relatively strong outflows compared to Sy2s. This can be explained by the difference in IR luminosity contributed from active galactic nuclei,

(AGN), because we found that (i)

(AGN) correlates with the velocity offset and dispersion of [O iii] and (ii) our IR-bright DOG sample has larger

(AGN) than Sy2s. Nevertheless, the fact that about 75% IR-bright DOGs have a large (>300 km s−1) velocity dispersion, which is a larger fraction compared to other AGN populations, suggests that IR-bright DOGs are good laboratories to investigate AGN feedback. The velocity offset and dispersion of [O iii] and [Ne iii]λ3869 are larger than those of [O ii]λ3727, which indicates that the highly ionized gas tends to show stronger outflows.
The ISLAnds Project. III. Variable Stars in Six Andromeda Dwarf Spheroidal Galaxies*
Authors: Martínez-Vázquez Clara E. , Monelli Matteo , Bernard Edouard J. , Gallart Carme , Stetson Peter B. , Skillman Evan D. , Bono Giuseppe , Cassisi Santi , Fiorentino Giuliana , McQuinn Kristen B. W. , Cole Andrew A. , McConnachie Alan W. , Martin Nicolas F. , Dolphin Andrew E. , Boylan-Kolchin Michael , Aparicio Antonio , Hidalgo Sebastian L. , Weisz Daniel R.
Published: November 2017

We present a census of variable stars in six M31 dwarf spheroidal satellites observed with the Hubble Space Telescope. We detect 870 RR Lyrae (RRL) stars in the fields of And I (296), II (251), III (111), XV (117), XVI (8), and XXVIII (87). We also detect a total of 15 Anomalous Cepheids, three eclipsing binaries, and seven field RRL stars compatible with being members of the M31 halo or the Giant Stellar Stream. We derive robust and homogeneous distances to the six galaxies using different methods based on the properties of the RRL stars. Working with the up-to-date set of Period-Wesenheit (I, B–I) relations published by Marconi et al., we obtain distance moduli of μ
0 = [24.49, 24.16, 24.36, 24.42, 23.70, 24.43] mag (respectively), with systematic uncertainties of 0.08 mag and statistical uncertainties <0.11 mag. We have considered an enlarged sample of 16 M31 satellites with published variability studies, and compared their pulsational observables (e.g., periods and amplitudes) with those of 15 Milky Way satellites for which similar data are available. The properties of the (strictly old) RRL in both satellite systems do not show any significant difference. In particular, we found a strikingly similar correlation between the mean period distribution of the fundamental RRL pulsators (RRab) and the mean metallicities of the galaxies. This indicates that the old RRL progenitors were similar at the early stage in the two environments, suggesting very similar characteristics for the earliest stages of evolution of both satellite systems.
Biases in Metallicity Measurements from Global Galaxy Spectra: The Effects of Flux Weighting and Diffuse Ionized Gas Contamination
Authors: Sanders Ryan L. , Shapley Alice E. , Zhang Kai , Yan Renbin
Published: November 2017

Galaxy metallicity scaling relations provide a powerful tool for understanding galaxy evolution, but obtaining unbiased global galaxy gas-phase oxygen abundances requires proper treatment of the various line-emitting sources within spectroscopic apertures. We present a model framework that treats galaxies as ensembles of H ii  and diffuse ionized gas (DIG) regions of varying metallicities. These models are based upon empirical relations between line ratios and electron temperature for H ii  regions, and DIG strong-line ratio relations from SDSS-IV MaNGA IFU data. Flux-weighting effects and DIG contamination can significantly affect properties inferred from global galaxy spectra, biasing metallicity estimates by more than 0.3 dex in some cases. We use observationally motivated inputs to construct a model matched to typical local star-forming galaxies, and quantify the biases in strong-line ratios, electron temperatures, and direct-method metallicities as inferred from global galaxy spectra relative to the median values of the H ii  region distributions in each galaxy. We also provide a generalized set of models that can be applied to individual galaxies or galaxy samples in atypical regions of parameter space. We use these models to correct for the effects of flux-weighting and DIG contamination in the local direct-method mass–metallicity and fundamental metallicity relations, and in the mass–metallicity relation based on strong-line metallicities. Future photoionization models of galaxy line emission need to include DIG emission and represent galaxies as ensembles of emitting regions with varying metallicity, instead of as single H ii  regions with effective properties, in order to obtain unbiased estimates of key underlying physical properties.
Radiation Hydrodynamical Turbulence in Protoplanetary Disks: Numerical Models and Observational Constraints
Authors: Flock Mario , Nelson Richard P. , Turner Neal J. , Bertrang Gesa H.-M. , Carrasco-González Carlos , Henning Thomas , Lyra Wladimir , Teague Richard
Published: November 2017

Planets are born in protostellar disks, which are now observed with enough resolution to address questions about internal gas flows. Magnetic forces are possibly drivers of the flows, but ionization state estimates suggest that much of the gas mass decouples from magnetic fields. Thus, hydrodynamical instabilities could play a major role. We investigate disk dynamics under conditions typical for a T Tauri system, using global 3D radiation-hydrodynamics simulations with embedded particles and a resolution of 70 cells per scale height. Stellar irradiation heating is included with realistic dust opacities. The disk starts in joint radiative balance and hydrostatic equilibrium. The vertical shear instability (VSI) develops into turbulence that persists up to at least 1600 inner orbits (143 outer orbits). Turbulent speeds are a few percent of the local sound speed at the midplane, increasing to 20%, or 100 m s−1, in the corona. These are consistent with recent upper limits on turbulent speeds from optically thin and thick molecular line observations of TW Hya and HD 163296. The predominantly vertical motions induced by the VSI efficiently lift particles upward. Grains 0.1 and 1 mm in size achieve scale heights greater than expected in isotropic turbulence. We conclude that while kinematic constraints from molecular line emission do not directly discriminate between magnetic and nonmagnetic disk models, the small dust scale heights measured in HL Tau and HD 163296 favor turbulent magnetic models, which reach lower ratios of the vertical kinetic energy density to the accretion stress.
3D Polarized Imaging of Coronal Mass Ejections: Chirality of a CME
Authors: DeForest C. E. , de Koning C. A. , Elliott H. A.
Published: November 2017

We report on a direct polarimetric determination of the chirality of a coronal mass ejection (CME), using the physics of Thomson scattering applied to synoptic polarized images from the Solar Terrestrial Relations Observatories/COR2 coronagraph. We confirmed the determination using in situ magnetic field measurements of the same CME with the ACE spacecraft. CME chirality is related to the helicity ejected from the solar corona along with the mass and field entrained in the CME. It is also important to prediction of the space-weather-relevant Z component of the CME magnetic field. Hence, remote measurement of CME chirality is an important step toward both understanding CME physics and predicting geoeffectiveness of individual CMEs. The polarimetric properties of Thomson scattering are well known and can, in principle, be used to measure the 3D structure of imaged objects in the solar corona and inner heliosphere. However, reduction of that principle to practice has been limited by the twin difficulties of background subtraction and the signal-to-noise ratio in coronagraph data. Useful measurements of the 3D structure require relative photometry at a few percent precision level in each linear polarization component of the K corona. This corresponds to a relative photometric precision of order 10−4 in direct images of the sky before subtraction of the F corona and related signal. Our measurement was enabled by recent developments in signal processing, which enable a better separation of the photometric signal from noise in the synoptic COR2 data. We discuss the relevance of this demonstration measurement to future instrument requirements, and to the future measurements of 3D structures in CMEs and other solar wind features.
Low-mass Pre-He White Dwarf Stars in Kepler Eclipsing Binaries with Multi-periodic Pulsations
Authors: Zhang X. B. , Fu J. N. , Liu N. , Luo C. Q. , Ren A. B.
Published: November 2017

We report the discovery of two thermally bloated low-mass pre-He white dwarfs (WDs) in two eclipsing binaries, KIC 10989032 and KIC 8087799. Based on the Kepler long-cadence photometry, we determined comprehensive photometric solutions of the two binary systems. The light curve analysis reveals that KIC 10989032 is a partially eclipsed detached binary system containing a probable low-mass WD with the temperature of about 10,300 K. Having a WD with the temperature of about 13,300, KKIC 8087799 is typical of an EL CVn system. By utilizing radial velocity measurements available for the A-type primary star of KIC 10989032, the mass and radius of the WD component are determined to be

and

, respectively. The values of mass and radius of the WD in KIC 8087799 are estimated as 0.16 ± 0.02 M
⊙ and 0.21 ± 0.01 R
⊙, respectively, according to the effective temperature and mean density of the A-type star derived from the photometric solution. We therefore introduce KIC 10989032 and KIC 8087799 as the eleventh and twelfth dA+WD eclipsing binaries in the Kepler field. Moreover, both binaries display marked multi-periodic pulsations superimposed on binary effects. A preliminary frequency analysis is applied to the light residuals when subtracting the synthetic eclipsing light curves from the observations, revealing that the light pulsations of the two systems are both due to the δ Sct-type primaries. We hence classify KIC 10989032 and KIC 8087799 as two WD+δ Sct binaries.
Plasma Beta Stratification in the Solar Atmosphere: A Possible Explanation for the Penumbra Formation
Authors: Bourdin Ph.-A.
Published: November 2017

Plasma beta is an important and fundamental physical quantity in order to understand plasma dynamics, particularly in the context of magnetically active stars, because it tells about the domination of magnetic versus thermodynamic processes on the plasma motion. We estimate the value ranges of plasma beta in different regions within the solar atmosphere and we describe a possible mechanism that helps forming a penumbra. For that we evaluate data from a 3D magnetohydrodynamic model of the solar corona above a magnetically active region. We compare our results with previously established data that is based on magnetic field extrapolations and that was matched for some observations. Our model data suggest that plasma beta in the photosphere should be considered to be larger than unity outside of sunspots. However, in the corona we also find that the beta value range reaches lower than previously thought, which coincides with a recent observation. We present an idea based on a gravity-driven process in a high-beta regime that might be responsible for the formation of the penumbra around sunspot umbra, where the vertical field strength reaches a given threshold. This process would also explain counter-Evershed flows. Regarding the thermal and magnetic pressure within the mixed-polarity solar atmosphere, including non-vertical magnetic field and quiet regions, plasma beta may reach unity at practically any height from the photosphere to the outer corona.
Photoionization Modeling of Titan’s Dayside Ionosphere
Authors: Shebanits O. , Vigren E. , Wahlund J.-E. , Edberg N. J. T. , Cui J. , Mandt K. E. , Waite J. H.
Published: November 2017

Previous modeling studies of Titan’s dayside ionosphere predict electron number densities that are roughly a factor of 2 higher than those observed by the RPWS/Langmuir probe. The issue can equivalently be described as the ratio between the calculated electron production rates and the square of the observed electron number densities resulting in roughly a factor of 4 higher effective recombination coefficient than expected from the ion composition and the electron temperature. Here we make an extended reassessment of Titan’s dayside ionization balance, focusing on 34 flybys between TA and T120. Using a recalibrated data set and by taking the presence of negative ions into account, we arrive at lower effective recombination coefficients compared with earlier studies. The values are still higher than expected from the ion composition and the electron temperature, but by a factor of ∼2–3 instead of a factor of ∼4. We have also investigated whether the derived effective recombination coefficients display dependencies on the solar zenith angle (SZA), the integrated solar EUV intensity (

nm), and the corotational plasma ram direction (RAM), and found statistically significant trends, which may be explained by a declining photoionization against the background ionization by magnetospheric particles (trends in SZA and RAM) and altered photochemistry (trend in EUV). We find that a series of flybys that occurred during solar minimum (2008) and with similar flyby geometries are associated with enhanced values of the effective recombination coefficient compared with the remaining data set, which also suggests a chemistry dependence on the sunlight conditions.
Using the hybrid fuzzy goal programming model and hybrid genetic algorithm to solve a multi-objective location routing problem for infectious waste disposal
Authors: Wichapa Narong , Khokhajaikiat Porntep
Published: November 2017

Purpose: Disposal of infectious waste remains one of the most serious problems in the social and environmental domains of almost every nation. Selection of new suitable locations and finding the optimal set of transport routes to transport infectious waste, namely location routing problem for infectious waste disposal, is one of the major problems in hazardous waste management.Design/methodology/approach: Due to the complexity of this problem, location routing problem for a case study, forty hospitals and three candidate municipalities in sub-Northeastern Thailand, was divided into two phases. The first phase is to choose suitable municipalities using hybrid fuzzy goal programming model which hybridizes the fuzzy analytic hierarchy process and fuzzy goal programming. The second phase is to find the optimal routes for each selected municipality using hybrid genetic algorithm which hybridizes the genetic algorithm and local searches including 2-Opt-move, Insertion-move and ?-interchange-move.Findings: The results indicate that the hybrid fuzzy goal programming model can guide the selection of new suitable municipalities, and the hybrid genetic algorithm can provide the optimal routes for a fleet of vehicles effectively.Originality/value: The novelty of the proposed methodologies, hybrid fuzzy goal programming model, is the simultaneous combination of both intangible and tangible factors in order to choose new suitable locations, and the hybrid genetic algorithm can be used to determine the optimal routes which provide a minimum number of vehicles and minimum transportation cost under the actual situation, efficiently.
Measuring Success: Goals and Outcomes for Educational Programs
Authors: Taylor Suzanne , Hall Sandy
Published: November 2017

Measuring outcomes for educational programs can be challenging for many nursing professional development (NPD) practitioners. Alignment of goals with outcomes provides the foundation for the educator to justify, evaluate, and improve programs with more efficiency. This article highlights lessons learned by NPD practitioners after successful justification for continued support of educational programs.

J Contin Nurs Educ.
2017;48(12):537–538.
Knowledge Level and Educational Needs of Turkish Oncology Nurses Regarding the Genetics of Hereditary Breast and Ovarian Cancer
Authors: Seven Memnun , Pasalak S. Inciser , Guvenc Gulten , Kok Gulsah
Published: November 2017

Background:

This study evaluated Turkish oncology nurses' knowledge and educational needs regarding genetics of hereditary breast and ovarian cancers.

Method:

An online survey was used to collect data from 104 Turkish oncology nurses.

Results:

The mean level of knowledge in oncology genetics was 6.74 ± 3.85. The majority of nurses (78.7%) were aware of the fact that family history of ovarian or breast cancer is an important risk factor for ovarian or breast cancer; however, a much smaller percentage (25.5%) understood that BRCA1 mutations in women can be transferred by the father. The majority of the nurses (59.6%) were willing to take continuing education in cancer genetics.

Conclusion:

Turkish oncology nurses have a moderate level of knowledge in cancer genetics. Therefore, educators should develop targeted educational activities in genetics as a part of continuing education programs to enhance nursing practice in cancer care.

J Contin Educ Nurs.
2017;48(12):570–576.
Primer registro de Phisidia oculata (Langerhans, 1881) (Annelida, Terebellidae) tras la descripción original
Authors: Jirkov I. A. , Parapar J. , Moreira J.
Published: November 2017

El examen de dos ejemplares de Terebellidae depositados en el Museo Nacional de Ciencias Naturales, Madrid, procedentes de las Islas Chafarinas ha revelado su pertenencia a la especie Phisidia oculata (Langerhans, 1881). Este es el primer registro de la especie tras su descripción original, por lo que se realiza una descripción de los mismos, indicando las principales características morfológicas que permiten su reconocimiento frente a otras especies cogenéricas y a otros géneros próximos, incluyendo una tabla sinóptica con las principales características de las especies del género Phisidia.
Caracterización experimental de las emisiones de nanopartículas en el tratamiento de AA6061, AISI304 y Ti6Al4V por ondas de choque generadas por LASER
Authors: Gomes João F. , Miranda Rosa M. , Porro Juan A. , Ocaña José L.
Published: November 2017

Este artículo es un estudio experimental sobre la caracterización de las emisiones de nanopartículas en el tratamiento superficial por ondas de choque generadas por LASER (LSP) de materiales metálicos: aceros inoxidables, aleaciones de aluminio y de titanio. Se confirmó que la emisión de partículas de tamaño nanométrico consiste en agregados compuestos de partículas esféricas en el rango de 10-20 nm, cubiertas por una pequeña “capa” concéntrica correspondiente a óxidos metálicos. El análisis de las nanopartículas mostró la presencia de los principales elementos presentes en las aleaciones ensayadas, y también un contenido elevado de oxígeno que corrobora la presencia de óxidos de Fe, Al y Ti. La cantidad de nanopartículas emitidas, mostró aumentos considerables sobre la línea de base medida para el ambiente de trabajo, y estos aumentos corresponden a los impulsos más intensos de LASER. Se observó que la densidad del material influí en la cantidad de nanopartículas emitidas. Durante el LSP de aleación de aluminio (el material más ligero) se midió una gran cantidad de nanopartículas, mientras que en LSP de acero inoxidable se observaron pocas nanopartículas, y este es el material más denso, entre los tres ensayados. La aleación de titanio da como resultado valores intermedios. El estudio de estas emisiones es innovador y relevante para entornos industriales donde el proceso de fabricación está en uso.
La eliminación de metales tóxicos presentes en efluentes líquidos mediante resinas de cambio iónico. Parte V: níquel(II))/H+/Dowex C400
Authors: Alguacil Francisco José
Published: November 2017

Se ha empleado la resina de intercambio catiónico Dowex C400 en la eliminación de níquel(II) de disoluciones acuosas de distintos valores de pH y en varias condiciones experimentales: velocidad de agitación del sistema acuoso/resina, temperatura, dosificación de la resina y disoluciones acuosas de distinta fuerza iónica, investigándose la eliminación del níquel de medios acuosos que contenían varios metales, así como las posibilidades de la resina frente a la utilización de otros potenciales adsorbentes como son los nanotubos de carbono de pared múltiple y los nanotubos de carbono de pared múltiple funcionalizados con grupos carboxílicos. Los resultados experimentales indican que la carga del níquel(II) en la resina responde al modelo de Freundlich, mientras que los modelos cinéticos y de control indican que el proceso de intercambio catiónico responde al modelo de pseudo-primer orden y núcleo recesivo. La elución del níquel(II) se realiza con disoluciones acidas.
An Evaluation of Instructional Process of Expert System Course Program by Using Mobile Technology-based CSE-UCLA Model
Authors: Divayana Dewa Gede Hendra , Sappaile Baso Intang , Pujawan I Gusti Ngurah , Dibia I Ketut , Artaningsih Luh , Sundayana I Made , Sugiharni Gusti Ayu Dessy
Published: November 2017

One of various types of application program which could facilitate human activities is known as expert system application program. The concept of the expert system of the application program so important that it requires to be shared to other people by developing a course program called expert system conducted in particular by an institution which specialized in the field of information technology. This course program of expert system which is offered to the students need to be designed in terms of good instructional process to improve its effectiveness. In fact, not all existing course programs conducted based on expert system could run more effectively than it was expected in order to achieve higher quality of learning outcomes. This could be explained as a numerous problems occurred during the process of implementation. In order to discover the extend of program effectivity in the expert system of the course, a through program evaluation is required to be conducted. One model called CSE-UCLA will be recommended in making deeper instructional program evaluation in relation to expert system of course program. Through this model the instructional affectivity of application program of expert system could be measured by involving system assessment, program planning, program implementation, program improvement, and program certification.
Social Media: A New Way of Public and Political Communication in Digital Media
Authors: Coelho Patricia M. F. , Correia Pedro Pereira , Medina Irene Garcia
Published: November 2017

Today, social media are the new way of public and political communication in digital marketing. Companies or organizations are no longer the exclusive owners of the relation of consumers with their products/services; instead, the survival of the organizations depends of the effective utilization of the social media. New web technologies have made it easy for anyone to create and distribute their own content.  A tweet can be viewed by virtually millions of people for free, and advertisers don’t have to pay publishers huge sums of money to embed their messages. More consumers are on social media than ever before, and every second a company is not engaged is a wasted opportunity [1]. Consumers trust other people to provide recommendations about products and services in a very active way and it is important to know how and why social media influence organizations. This study analyzes through a literature review the importance of public and political communication through social media and proposes a model of business for successful marketing strategies.
Health Website Success: User Engagement in Health-Related Websites
Authors: Imlawi Jehad
Published: November 2017

Health-related websites are increasingly accessed on the Internet. More online users are using health-related websites, and rely on it to get answers for their health questions. Health care providers try to develop websites that focus on the users’ needs. One of the key factors, to develop users' driven health-related websites, is supporting users’ engagement.

This study proposes a research model that investigates factors that are critical to users’ engagement in health-related websites. Three factors were identified accordingly; website usability, website interactivity, and users' perceived health information quality. A limited amount of research has previously explored such a thorough list.
240 respondents participated in an online survey, to test the research model. Results show that the engagement antecedents identified by the study are significant, and explain a great percentage of the variance for the engagement. The study concluded by implications for theory and practice.
Investigating the Perception of Students Regarding M-Learning Concept in Egyptian Schools
Authors: Adel Ali Reham , Rafie Mohd Arshad Muhammad
Published: November 2017

The Egyptian school education systems is currently in a miserable state and facing some problems. To overcome the problems, there is a suggestion towards the development and implementation of mobile learning (m-Learning) as a new learning tool in the education system. The aim of this paper is to investigate  the Egyptian students’  perception towards m-learning as a new learning tool and its benefits through a survey of 120 students from a public preparatory school in Egypt. Data was gathered and analyzed using Statistical Package for Social Science (SPSS) Version 23. The results demonstrated a positive attitude from the participants towards the benefits of M-learning. The majority of students showed their concerns about technical issues of m-learning such as the small screen and limited storage. The results also revealed the positive attitude towards the value of M-learning, especially for those who use E-learning resources. A large proportion of participants use their devices for different activities such as messages, Internet browsing and games rather than learning. This has point the need for more investigation to determine the factors that may affect the students' intention to use their devices in learning.
Historical urban warehouses in Brussels: architecture and construction
Authors: De Fossé Marianne
Published: November 2017

Historical urban warehouses are remarkable structures. Today, however, and despite their robust architecture, they have become vulnerable urban heritage threatened with demolition. Current research being carried out at the Vrije Universiteit Brussel focuses on the development of knowledge about the architecture, operation and construction of warehouses in Antwerp, Brussels and Ghent and their integration in the urban fabric, to support their preservation and respectful adaptive reuse. This paper contains the results of in-depth archival and first on-site investigations of nineteenth and twentieth-century warehouses in the historic city centre of Brussels, covering the first industrial zone around the river Senne and the docks. Eighty demolished and still existing urban warehouses are analysed by focusing first on the storage of some well-represented goods: hay, timber, beer and textile. The analysis shows that the four goods correspond to four types of warehouses that differ in their architecture, organisation, construction and integration in the urban fabric.
Utilising 3D Realistic Models in Serious Games for Cultural Heritage
Authors: Kontogianni Georgia , Koutsaftis Christos , Skamantzari Margarita , Chrysanthopoulou Christina , Georgopoulos Andreas
Published: November 2017

In the cultural heritage field, many Serious Games applications have been developed whose goal is to educate players and users not particularly specialized or familiar with this field. On the other hand, 3D models of cultural heritage objects created with precise 3D modelling methods can be a very useful asset for these applications. In this paper a composite Serious Game for the Stoa of Attalos, a prominent monument in the Ancient Athens Agora, is developed and presented. 3D models are used, which were produced mainly with automated image based modelling techniques. The creation of the 3D models is described and presented along with the development of the application, which offers three options for the player. These options are: a quiz game, a 3D visual quiz and a virtual museum. The user interaction is described and, based on an evaluation questionnaire, the application is assessed by a group of people in the Cultural Heritage field.
Technological Ensuring of Production Competitiveness of Mining and Processing Enterprises
Authors: Cherep Andrii , Pilova Dar'ya
Published: November 2017

The significant reduction in the volume of production of concentrate at the Ordzhonikidzevsky mining and processing enterprise, which led to an increase in the cost of manganese ore and concentrate due to the increase in specific conditional-fixed costs for mining of overburden rocks by the bucket wheel complexes is analyzed. The dependencies between the cost of ore and concentrate on the volume of ore production and concentrate production are determined. As a result of the unevenness of production volumes and the unevenness of the volumes of shipment of production that do not coincide with each other, is substantiated that the mining and processing enterprise has to block certain amounts of funds, which leads to increased production costs.
Designing, Processing and Isothermal Transformation of Al-Si Medium Carbon Ultrafine High Strength Bainitic Steel
Authors: Abd El Rahman Sherif Ali , Shash Ahmed , El-Fawkhry Mohamed K. , Farahat Ahmed Zaki , Mattar Taha
Published: November 2017

Medium-carbon, silicon-rich steels are commonly suggested to obtain a very fine bainitic microstructure at a low temperature slightly above Ms. Thereby, the resulted microstructure consists of slender bainitic-ferritic plates interwoven with retained austenite. The advanced strength and ductility package of this steel is much dependent on the fineness of bainitic ferrite, as well as the retained austenite phase. In this article, the aluminum to silicon ratio, and the isothermal transformation temperature have been adopted to obtain ultra-high strength high carbon steel. Optical and SEM investigation of the produced steels have been performed. XRD has been used to track the retained austenite development as a result of the change in the chemical composition of developed steels and heat treatment process. Mechanical properties in terms of hardness and microhardness of obtained phases and structure were investigated. Results show that the increment of aluminum to silicon ratio has a great effect in promoting the bainitic transformation, in tandem with improving the stability and the fineness of retained austenite. Such an advanced structure leads to enhancement in the whole mechanical properties of the high carbon steel.
Technical and Economic Viability for the Briquettes Manufacture
Authors: da Silva Bibiana Porto , Saccol Fernando , Caetano Nanton Roberto , Pedrazzi Cristiane , Caetano Nattan Roberto
Published: November 2017

This work aimed to evaluate the production briquettes cost, using two samples of forest residues from paper and pulp companies. The samples approached in this study were chips of Eucalyptus spp. and bark of Pinustaeda. The conditions to produce the briquettes were: pressure of 100 bar, temperature of 393 K (± 5 K), pressing time of 3 minutes and cooling time of 5 minutes. While the conditions previously used for this work were: 150 bar pressure, 393 K (± 5 K) temperature, 5 minute pressing time and 6 minute cooling time. The compaction levels remained the same and no cracking was observed. Quality parameters of the briquettes were also evaluated and were analyzed the costs of briquetting process in different stages. The most energy consuming stage was the briquetting process for both samples, this stage dominates the briquettes producing cost. The briquettes production cost was 415.70 and 508.96 R$/ton, Eucalyptus spp. and Pinustaeda, respectively, while using the previously technique would cost 603.22 and 817.06 R$/ton. The total briquetting costs obtained in this study are higher than the literature, because the manufacturing process was not performed in an industrial scale.
The Effect of Partitioning on the Clustering Index of Randomly-Oriented Fiber Composites: A Parametric Study
Authors: Javanbakht Zia , Hall Wayne , Öchsner Andreas
Published: November 2017

In the current study, five cases of fiber distributions are considered in a fiber-reinforced composite: one random, three partitioned (one uniform and two biased cases), and one aligned case for benchmarking. The finite element method and the principal component analysis were used to interpret the results of orientation tensors and detect any possible clusterings of a representative volume element (RVE). The obtained effective conductivity values were extensively controlled by the fiber volume fraction. At the same time, the uniformity of the random distributions could be recognized. Cross-partition resistance was also detected for the partitioned cases which contributed to a reduced heat transfer capability. Finally, the clustering indexes did not show a direct correlation with the conductivity results, and thus a case-by-case investigation is recommended to consider the anisotropic aspects of a microstructure.
Control of Particle Size and Morphology of MOF-199 Crystals via a Reaction-Diffusion Framework
Authors: Issa Razan , Hmadeh Mohamad , Al-Ghoul Mazen
Published: November 2017

A reaction-diffusion framework (RDF) is used to synthesize and control the size and morphology of single crystals of metal-organic framework-199 (MOF-199). The framework consists of diffusing copper ions (Cu2+, outer electrolyte) into a hydrogel medium containing the organic linker, 1,3,5-benzenetricarboxylic acid (BTC, inner electrolyte). The resulting supersaturation gradient, and its nonlinear coupling with nucleation and growth kinetics, provides means to control the crystal size, distrubution and morphology along the diffusion flux. This method is rapid, efficient, scalable, and environmentally friendly. By using this method we demonstrate how assorted experimental parameters, such as temperature, concentrations, and nature of the gel matrix can be easily tuned to produce different particle size distributions and various morphologies.
Manufacturing Fiber-Reinforced Polymer Composite Using RTM Process: An Analytical Approach
Authors: do Nascimento Santos M.J. , Barbosa de Lima A.G.
Published: November 2017

The Resin Transfer Molding process (RTM) has been widely used for manufacturing of high performance components in aerospace and automotive industries. It is an economical and faster method when compared to open molding process because it allows the molding of complex parts with constant thickness, dimensional precision, good surface finishing and an excellent control of mechanical properties. In this sense, this work aims to study theoretically the manufacture process of polymeric composites reinforced with fibers via resin transfer molding. The governing equations of conservation of mass and momentum, and Darcy's law are presented, and the exact solution of the problems is obtained via method of separation of variables. Predicted results of the flow front and the pressure fields of the resin inside the model during the injection process are presented, compared with experimental data and analyzed. It was verified a good agreement between the results.
The Effect of the Drying Temperature on the Moisture Removal and Mechanical Properties of Sisal Fibers
Authors: Gomes dos Santos D. , Barbosa de Lima A.G. , de Sousa Costa P.
Published: November 2017

Vegetable fibers have been used in most several applications, as raw material, for manufacturing of different products or directly as reinforcement in composite materials. Green fibers are wet, what requires its drying before their use.In this sense, the aim of this work is to study drying of the sisal fibers in oven. Drying experiments were carried out at different drying condition. It was evaluated the curves of moisture content, drying and heating rates and temperature, as well as the influence of the drying temperature on the mechanical properties of the fibers. It was found that the drying temperature (60 - 105°C) had no significant influence on the tensile mechanical properties, elongation at rupture and modulus of elasticity of the sisal fibers.
Application of Metallographic Analysis Techniques for Detection and Identification of Spray Paint Defects
Authors: Remešová Michaela , Klakurková Lenka , Ročňáková Ivana , Čelko Ladislav , Páleníková Lucie , Kaiser Jozef
Published: November 2017

The paper is focused on the metallographic analysis of spray paint films with defects. The painting has two important roles. Firstly, it protects the substrate material (ferrous, nonferrous and plastic) and secondly, it improves the appearance of the surface. Appearance and quality of painting film play an important role in the industry (automotive, aerospace, consumer electronics, etc.). Defects of spray painting film, which have a negative effect on the appearance of the product, can be detected and further analysed by common methods used in metallography. Such methods are very effective tool for revealing the cause of defects and their elimination within the technological process (degreasing, cleaning, pickling, drying, technological discipline, etc.). In this paper, defects were characterized by high-resolution digital microscope (LM) and scanning electron microscope (SEM) equipped with energy dispersive X-ray analyser (EDX).
Analysis of Pipeline Serviceability for Water Supply to Power Plant
Authors: Chvostová Eva , Podaný Pavel , Konopík Pavel
Published: November 2017

The paper deals with residual serviceability of pipelines that are used for water supply and water drainage to/from the energy sector. During maintenance, some excessively corroded segments were observed. Using mobile microscopy, the material of these segments was analyzed on-site, and samples were taken from the pipeline for further microstructure analysis and mechanical properties in the laboratory. The sampling device is specifically designed to draw a small amount of experimental material (approx. 20 x 20 x 3 mm) from the operating components, and since it leaves only a small cavity on site, it is usually possible to continue operating components without repair. To evaluate the mechanical properties of the collected material, it was necessary to use newly developed tests on miniature bodies.
Combining 3D Scanning with Standard Microscopy Methods for Assessment of Pitting Corrosion in Turbine Blades
Authors: Bublíková Petra , Habrcetl Vlastimil , Mareš Pavel , Janura Roman , Kobzová Alena , Vávrovcová Zuzana
Published: November 2017

Pitting corrosion is a known process in metals. Pitting, observed in turbine blades, is caused by corrosion mechanisms in operation environment that may contain aggressive chemical compounds. Environment, material composition and operating conditions determine the corrosion process causing a cavity formation and their critical growth. Crack initiation can be a following mechanism. Thus the critical cavity size is the important parameter and its precise estimation can avoid a turbine blade failure. Cavity shape as well as corrosion products inside cavities should be taken into account. 3D scanning technique performed during turbine shutdowns is shown to be a suitable method for measurement of critical cavity size. In this study, the accuracy of 3D technique was confirmed by standard sample preparation methods followed by microscopy focused on corrosion products observation. Cross-sectioning of blades was performed close to the cavities, sections were grinded to show the maximum cavity dimensions and finally polished. Cavity size was measured in few steps by Light Optical Microscopy during grinding to find the maximum dimensions and compare to 3D measurements. Local corrosion in cavities was evaluated by Scanning Electron Microscopy using Backscattered Electrons and Energy Dispersive X-ray Spectroscopy. Non-uniform Fe, Cr, Si rich oxides with dimensions from tens up to hundreds of micrometres were analysed in cavities. No significant effect on oxide removing was observed after using sandblasting technology except possible effect in larger pits. Cracks and pores were detected close to the vicinity of trailing edge of blade.
Failure of a Rotating Blade of a 200 MW Steam Turbine LP Rotor and Options for Eliminating other Similar Breakdowns
Authors: Kasl Josef , Matějová Miroslava , Mrštík Jakub
Published: November 2017

This contribution deals with the analysis of the failure of a rotating blade of the third wheel (L-1 stage) of the LP rotor of a 200 MW turbine at the power station in Počerady. Material analysis of the blade showed that the cause of the blade fracture was the initiation and growth of a fatigue crack from a corrosion pit. Failures of low-pressure blades have occurred repeatedly on machines of the same design in the power stations of the ČEZ group in recent years and by a similar mechanism. Therefore, based on the knowledge obtained by EPRI (Electric Power Research Institute), ČEZ, a.s. has developed a methodology which can, in real conditions during checks of turbines, reliably detect the parameters of corrosion pits and predict the possibility of development of fatigue damage from these pits. The work summarizes the methodology and the conditions of its use with an emphasis on the fields of its application.
AZ31 and WE43 Alloys for Biomedical Applications
Authors: Dvorský Drahomír , Kubásek Jiří , Vojtěch Dalibor
Published: November 2017

Magnesium and its alloys are considered for application as materials for biodegradable implants as they have mechanical properties similar to bone tissue. High demands on corrosion and mechanical properties are made on these alloys. While mechanical properties of magnesium are usually enhanced by alloying, corrosion properties may deteriorate. This paper is focused on the comparison of magnesium alloys AZ31 (3 wt. % Al, 1 wt. % Zn) and WE43 (4 wt. % Y, 3 wt. % Nd) which are considered for biomedical applications. Besides the type of alloying elements, the preparation process has also great impact on final mechanical and corrosion properties. Alloying elements may be dissolved in magnesium matrix or they can form intermetallic phases, which alter final properties. Microstructure, mechanical and corrosion properties of AZ31 and WE43 were studied and compared with pure magnesium.
Material Analysis of the Extended-Life Cobalt-Based Superalloys Used in the Manufacturing of Glass Tools
Authors: Jonšta Petr , Vlčková Irena , Jonšta Zdenĕk , Król Mariusz
Published: November 2017

Cobalt-based superalloys are among the most important materials for application in the demanding conditions of the glass industry. These superalloys with extended life are due to their excellent heat-resistant properties an important part of glass tools, especially of spinning discs. In the submitted paper, a material analysis of the commercially produced cast cobalt superalloy for spinning discs, including metallographic analysis supplemented by an electron X-ray analysis of minority phases, is carried out. An assessment of harmful gases, in particular oxygen and nitrogen, has also been carried out. They appear to be the cause of defects that often lead to the subsequent degradation of the material.
The Role of Different Atmospheric Plasma Spray Parameters on Microstructure of Abradable AlSi-Polyester Coatings
Authors: Jech David , Čelko Ladislav , Komarov Pavel , Ziegelheim Jindřich , Česánek Zdeněk , Schubert Jan
Published: November 2017

One of the approaches to increase the thermic efficiency of aerospace engines is the application of abradable coatings enabling minimization and control of the clearance between the stator and the rotating blades tips. The main purpose of this contribution is to define the role of different technological parameters utilized for atmospheric plasma spraying of AlSi-polyester coating on its resulting microstructure. Deposition of abradable coatings on the real engine parts is mostly dependent on spraying stand-off distance and on spraying angle. These two parameters influence not only the coating microstructure but also the deposition efficiency itself, which is directly connected with economical aspects of the coating production. The set of experimental samples with atmospheric plasma sprayed Ni-based bond coat and two in chemical composition same initial powders delivered from different powder manufacturers were used to spray thick AlSi-polymer top coats with different spraying stand-off distances and angles. Subsequently some of the samples were also heat treated to burn-out the polymer phase from the coating microstructure. The Rockwell HR15Y hardness was measured on all samples and the microstructure and coating thickness were evaluated by means of light microscopy and image analysis methods.
Investigations of Wettability of Wear Resistant Coatings Produced by Atmospheric Plasma Spraying
Authors: Komarov Pavel , Čelko Ladislav , Jech David , Papula Martin , Slámečka Karel , Horynová Miroslava , Klakurková Lenka , Kaiser Jozef
Published: November 2017

Changes in fluids contact angle in the interaction with materials surface can play a critical role in enhancement of hydro-machine components and pipelines efficiency and/or service lifetime. However most nowadays used materials and/or coatings are made from polymers or ceramic polymer composites produced by highly sophisticated and/or very expensive techniques. Unfortunately there are a lack of mechanical properties. With the aim to study the role of the surface topography on the water contact angle changes, the representatives of wear resistant coatings (WC10Co4Cr, Cr2O3+5SiO2+3TiO2 and Al2O3) were produced by means of atmospheric plasma spraying. Wettability of the coatings surface was studied by adding the liquid droplet on as sprayed, grinded and polished coating's surface by measuring the changes of its contact angle. To estimate the coatings phase composition and topography XRD technique and optical profilometer were used. The contact angle of water was measured by sessile droplet method. To obtain the complex information of the cross-sectional coatings microstructure the conventional metallographic analysis approaches and optical microscopy were also used.