bluuebunny/crossref_metadata_2025 huggingface dataset:
Prosodic accommodation and salience: The nuclear contours of Andalusian Spanish speakers in Asturias
Authors: Troncoso-Ruiz Aurora , Elordieta Gorka
Published: February 2018

This study investigates the convergent accommodating behaviour of Andalusian speakers (Southern Spain) relocated in Asturias (Northern Spain), a context of dialect contact, in terms of intonation. We aim to address three research questions: (1) is there evidence for accommodation? (2) Do social factors determine accommodation? And (3) does salience predict which prosodic features are more likely to be adopted by relocated speakers? We elaborated a corpus of spontaneous speech including an experimental group of Andalusian speakers in Asturias and two control groups of Asturian and Andalusian people. The relocated Andalusians were interviewed by a speaker of Andalusian Spanish and a speaker of Amestáu (hybrid variety between Asturian and Spanish), and their intonation patterns were compared to the ones found in the control populations. During the interviews, we also gathered data about how integrated these relocated speakers were in Asturias. We found that all participants show a tendency towards convergent accommodation to the Amestáu interlocutor, producing late falling pitch contours in nuclear position in declaratives and final falling contours in absolute interrogatives. The most integrated speakers in the Asturian community are the ones showing more features of the varieties spoken in the area. Finally, the most salient features to an Andalusian ear—the presence of final falls in Asturian, Asturian Spanish and Amestáu absolute interrogatives as opposed to final rises in Andalusian and Standard Peninsular Spanish—were the ones showing the highest percentages of adoption in relocated speakers. We could conclude, then, that the most salient prosodic features are acquired more easily by the most integrated relocated speakers.
El desarrollo liderado por los productos básicos en América Latina
Authors: Ocampo José Antonio
Published: February 2018

El presente capítulo analiza la evolución histórica de la dependencia de productos básicos en América Latina, mostrando que la dependencia de exportaciones intensivas en recursos naturales se incrementó durante el auge de precios de dichos productos de 2003-2013, sucediendo a un periodo de diversificación exportadora que se había iniciado a mediados de la década de 1960. Luego analiza la dinámica de los precios, mostrando que los precios de los productos básicos experimentaron tendencias de largo plazo que fueron generalmente adversas a los productos no petroleros a lo largo del siglo XX, así como superciclos de 30 a 40 años de duración. A partir de dicho patrón, el autor argumenta que el reciente colapso de precios puede ser el inicio de un largo periodo de precios débiles. Finalmente, el capítulo muestra que la región no ha sido capaz de aprovechar plenamente los beneficios de su especialización en recursos naturales y ha enfrentado, en cambio, algunos efectos negativos de la enfermedad holandesa debido a la dependencia antes mencionada. Además, América Latina ha sido víctima de las vulnerabilidades macroeconómicas generadas por los ciclos de los precios de los productos básicos, en gran medida por no haber logrado desarrollar políticas macroeconómicas contracíclicas apropiadas.
Dívida pública e financiamento da educação superior no Brasil
Authors: Chaves Vera Lúcia Jacob , Reis Luiz Fernando , Guimarães André Rodrigues
Published: February 2018

Objetivo deste artigo é apresentar os resultados da pesquisa realizada com a finalidade de analisar as implicações das políticas de ajuste fiscal no financiamento da educação superior brasileira, considerando o atendimento ao setor privado-mercantil, o orçamento destinado às universidades públicas federais e o pagamento da dívida pública, no período 2003-2016. Os dados financeiros foram extraídos do Tesouro Nacional, do Tribunal de Contas da União, do Senado Federal. Também se utilizaram documentos da KPMG Corporate Finance, da CM Consultoria, da Hoper Consultoria, da Associação Brasileira de Private Equity e Venture Capital (ABVCAP) e da Bolsa de Valores de São Paulo. Os resultados indicam que, mesmo diante da ampliação dos recursos destinados às universidades públicas federais, os valores são consideravelmente inferiores aos destinados à dívida pública. Também fica evidente que a expansão e a lucratividade do setor privado-mercantil são incentivadas pelas políticas do governo federal por meio do Programa Universidade para Todos (Prouni) e do Fundo de Financiamento Estudantil (Fies). Conclui-se, diante do congelamento dos gastos sociais federais nos próximos 20 anos, com a Emenda Constitucional n. 95/2016, aprofundando a política de ajuste fiscal, que as universidades públicas federais sofrerão consequências negativas para a sua manutenção, bem como será fortalecido o setor privado-mercantil.
Characteristics and Evolution Mechanism of Solidification Microstructure for Laser Additive Manufactured Ti2AlNb-Based Alloy
Authors: Tang Yang Jie , Zhang Yong Zhong , Liu Yan Tao , Pan Wei
Published: February 2018

Laser additive manufacturing (LAM) technology was applied to prepare Ti-22Al-25Nb alloy thin-wall sample. The characteristics and evolution mechanism of solidification microstructure were investigated, and the tensile properties at horizontal and vertical directions were discussed. The results indicated that the solidification microstructure in single deposition layer evolved as: plane crystal structure, cellular crystal structure, columnar dendrite structure and equiaxed dendrite structure, from the bottom to the top of the molten pool. During the solidification process, the temperature gradient and solidification velocity decided the grain growth morphology. However, the grain of the as-deposited materials grew up to thick equaxied structure when the upper layer was forming. The tensile properties at horizontal and vertical directions were not much different, both of these exhibited high strength and low ductility.
Property Requirements and Research Progress of Aluminum Alloy Sheets for Automotive Closure
Authors: Ma Ming Tu , Zhang Jun Ping , Zhou Jia , Lu Hong Zhou
Published: February 2018

Based on the requirements of automotive closure for production process and service performance, the property requirements of aluminum alloy sheet for automotive closure, including aging resistance stability, formability, bake hardening, dent resistance, flanging ductility, painting compatibility, etc., as well as introduced their test methods, evaluation characterization parameters, and the pre-aging process were discussed in this paper. Specially, the influential factors and control methods of spring-back of aluminum alloy sheet was discussed. The effect of the pre-aging process on the aging resistance stability and bake hardening of the aluminum alloy sheet for automotive was analyzed, and the property evolution of aluminum alloy sheet under industrial pre-aging process studied. The orange peel and roping phenomena of Al-Mg-Si alloy sheet after deformation were summarized as well.
A Comparative Study on the Friction and Wear Properties of Three Different Copper Alloys
Authors: Liu Dong Mei , Wang Qiang Song , Yuan Wei , Mi Xu Jun
Published: February 2018

A comparative study on the friction and wear properties of three kinds of copper alloys, including Cu-Ni based, Cu-Al and Cu-Be alloys was carried out in this study. The friction pair was stainless steel, and both dry and MoS2 lubrication friction experiments were investigated. During the experiments, different loads were chosen for different alloys. It was found that under dry friction condition, the friction coefficients of both Cu-Ni based and Cu-Al alloys did not change as the loads changes, whereas the friction coefficient of Cu-Be alloy increased as the loads increases. Under lubrication friction condition, the friction coefficients of all three alloys did not change as the load changes. The results show that the dry friction coefficient of Cu-Ni based alloy was the largest (0.74), the Cu-Al alloy next (0.60), and the Cu-Be alloy had the smallest dry friction coefficient (0.54). The lubrication friction coefficient of Cu-Ni based and Cu-Be was equal and relatively smaller (0.12), whereas the Cu-Al alloy had a relative larger lubrication friction coefficient (0.27). The microstructure observations were consistent with the friction and wear performance, and the SEM results show that different wear mechanisms were dominated for different alloys.
Cascade Collision near the Grain Boundary of Fe-Cr Alloy by MD Simulation
Authors: Mo Dan , Cai Jun , Li Ya Lin , Wang Yan Dong
Published: February 2018

Using molecular dynamics method to study the cascade collision for the case of PKA(Primary Knock-on Atom) atoms at different distance from the grain boundary(GB) of iron chromium alloy. It is found that the PKA atoms at the GB will produce a large size cluster (size from 11 to 409 ) consisting of interstitial and vacancies, and many small clusters (number from 5 to 50). The size and number of the cluster depend heavily on PKA energy, while depend weakly on temperature. The PKA atom at distance of 1nm from the GB, sometimes produces large size defect clusters both inside and outside the GB region. When the PKA atom is at 1nm, 2nm and even 3nm, 4nm from the GB, the GB will effectively absorb the interstitial atoms. It is found that the atomic ratio of Cr-interstitial to total interstitial produced at the GB region is much less than one at outside of GB region.
A Centimeter-Size High Toughness Zr-Cu-Al-Nb Bulk Metallic Glass with Nano-Crystallization and Phase Separation
Authors: Chen Chen , Jia Xiao Dong , Zhang Hang , Wei Ran , Li Fu Shan
Published: February 2018

In this paper, a centimeter-size Zr-Cu-Al-Nb bulk metallic glass (BMG) with high notch toughness of 107±13 MPa∙m0.5 was designed and fabricated by copper mold casting. With 1% Nb substitution for Zr in Zr48Cu45Al7 glass forming alloy, the glass forming ability (GFA) and toughness of the BMG were enhanced significantly. The coexistence of nano-crystallization and phase separation in the glassy matrix was observed in Zr47Cu45Al7Nb1, which would possibly lead to the high toughness of this alloy due to the easy and populous nucleation of shear bands and the increasing resistance of shear band propagation. The influences of nano-crystallization and phase separation on the toughness of BMGs are discussed in detail. The strategy utilized in this study provides a novel approach in search for new BMGs with high toughness and good GFA.
Preparation and Influencing Factors of Molybdenum Targets and Magnetron-Sputter-Deposited Molybdenum Thin Films
Authors: An Geng , Sun Jun , Sun Yuan Jun , Cao Wei Cheng
Published: February 2018

Aiming to produce qualified molybdenum (Mo) target for sputter deposition, Mo targets were prepared by utilizing powder metallurgy method in this research. The influences of sintering modes, press working modes and total deformation on microstructure and properties of Mo target were studied. Furthermore, magnetron sputtering test was conducted in vacuum environment by using the prepared Mo targets to deposit Mo thin films of which the surface morphologies, electrical conductivities, and crystalline properties were analyzed. The results show that vacuum presintering followed by hydrogen sintering mode can greatly decrease the impurity contents of Mo slabs. It is favorable to obtain the Mo target with fine and uniform grains on size and distribution by using forging mode or forging cogging mode and more than 70% total deformation. With the increase of sputtering currents of Mo target, the grain size and the thickness of the Mo thin films significantly rise, while FWHM of diffraction peaks of grain orientation (110), surface roughness and electrical resistivity of thin films decrease accordingly.
Effect of Triple Smelting Process on the Purity and Microstructure of 9Cr18Mo Bearing Steel
Authors: He Qu Bo , Wang Dong Zhe , Zhao An Zhong , Tang Rui , Liu Hai Ding , Chen Deng Hua , Mo Yan
Published: February 2018

In order to improve the purity of bearing steel, the VIM+ESR+VAR triple smelting process was used to smelt 9Cr18Mo stainless bearing steel. The content of harmful elements, non-metallic inclusions and microstructure of the steel were studied. The results show that, the content of harmful elements of the steel is very low. A fairly small number of non-metallic inclusions are uniformly distributed and fine. The purity of the steel reaches a higher level. After thermal processing and heat treatment, the microstructure of the steel is the same as 9Cr18Mo bearing steel smelted by normal process, but the primary carbides in the steel is more uniform distribution and finer.
Hollow Nitrogen Rich Carbon Nanowire Array Electrode for Application in Lithium-Ion Battery
Authors: Liu Yin Tian , Li Xiu Juan , Ji Yong Sheng , Hua Kang , Qin Meng , Luo Zhi Ping , Fang Dong
Published: February 2018

The anodic aluminum oxide template was prepared and used to fabricate polyacrylonitrile (PAN) nanowire arrays by mechanical hydraulic method, which provides a new idea for the preparation of polymer nanowires. By further carbonize the PAN nanowires at elevated temperatures, the porous nitrogen-rich carbon nanowires could be directly obtained and used as lithium-ion batteries anode material. The nitrogen-rich carbon nanowire based anode exhibited high initial capacities and maintained an outstanding reversible lithium storage capacity of 317.12 mAh g-1 after 50 cycles at a current density of 30 mA g-1, combined with an excellent rate capability of 317.17, 296.70, 265.02, 234.71, 177.02 mAh g-1 under the current density of 30, 50, 100, 200, 500 mA g-1 respectively. Further, this nitrogen-rich carbon nanowire material also has unique advantages in catalysis, supercapacitors and hydrogen storage application potential due to the porous carbon nanowire structure and the large amount of nitrogen doping.
CHARACTERIZATION AND ANTIMICROBIAL SUSCEPTIBILITY PROFILE OF SEPTICAEMIA-CAUSING PATHOGENS ISOLATED FROM FEBRILE CHILDREN WITH SICKLE CELL DISEASE IN KANO, NIGERIA.
Authors: Yusuf Ibrahim
Published: February 2018

Background and Objectives: Bacterial infection in sickle cell anaemic patients is a major cause of mortality and require proper treatment with appropriate antibiotics. However, continue defiant of these infections causing pathogens to many antibiotics and inadequate screening methods in overburden health care facilities such as our in Kano, Nigeria necessitates the conduct of this study. A research was therefore conducted on the characterizations and antimicrobial susceptibility of septicaemia-causing pathogens isolated from febrile children with sickle cell disease in Kano, Nigeria.Method: A total of 225 venous blood samples from suspected sickle cell anaemicchildren attending three selected hospitals within Kano metropolis were collected and screened for sickle cell disease, followed by blood culture using automated blood culture system (BD BACTEC) respectively. The bacteria isolated from confirmed SCD patients were characterized using microscopic, biochemical and serological techniques. Results: Results showed that of the 225 specimens collected,68 (30.22%) were SCD positive, with the highest percentage (16%) among subjects within 1-2 years of age.  A total of 11 genera of bacteria were isolated from the SCD confirmed bloods, with  Salmonella typhi having highest occurring rate 27 (39.71%), followed by Streptococcus pneumoniae10 (14.71%), Salmonella Group B 9(13.24%), Staphylococcus aureus 4 (5.88%),and Escherichia coli 3 (4.41%).Majority of the isolates 59 (86.76%) were highly susceptible to ciprofloxacin followed by cefuroxime 45 (66.18%), gentamicin 38 (55.88%), ceftriaxone 30 (44.12%), augmentin 39 (57.35%), ampicillin 25 (36.77%) and co-trimoxazole (22.06%). Conclusion: Septicaemia in SCD confirmed children in the three hospitals are caused by a combination of 11 genera of bacteria. Resistance to commonly used antibiotics are on increase, but treatment with ciprofloxacin is still promising.
Preventing Construct Subsidence Following Cervical Corpectomy: The Bump-stop Technique
Authors: Shaw Kenneth Aaron , Griffith Matthew , Mottern Edward T. , Gloystein David M. , Devine John G.
Published: February 2018

Cervical corpectomy is a viable technique for the treatment of multilevel cervical spine pathology. Despite multiple advances in both surgical technique and implant technology, the rate of construct subsidence can range from 6% for single-level procedures to 71% for multilevel procedures. In this technical note, we describe a novel technique, the bump-stop technique, for cervical corpectomy. The technique positions the superior and inferior screw holes such that the vertebral bodies bisect them. This allows for fixation in the dense cortical bone of the endplate while providing a buttress to corpectomy cage subsidence. We then discuss a retrospective case review of 24 consecutive patients, who were treated using this approach, demonstrating a lower than previously reported cage subsidence rate.
Community-specific hydraulic conductance potential of soil water decomposed for two Alpine grasslands by small-scale lysimetry
Authors: Frenck Georg , Leitinger Georg , Obojes Nikolaus , Hofmann Magdalena , Newesely Christian , Deutschmann Mario , Tappeiner Ulrike , Tasser Erich
Published: February 2018

Abstract. For central Europe in addition to rising temperatures an increasing
variability in precipitation is predicted. This will increase the probability
of drought periods in the Alps, where water supply has been sufficient in
most areas so far. For Alpine grasslands, community-specific imprints on
drought responses are poorly analyzed so far due to the sufficient natural
water supply. In a replicated mesocosm experiment we compared
evapotranspiration (ET) and biomass productivity of two differently
drought-adapted Alpine grassland communities during two artificial drought
periods divided by extreme precipitation events using high-precision small
lysimeters. The drought-adapted vegetation type showed a high potential to
utilize even scarce water resources. This is combined with a low potential to
translate atmospheric deficits into higher water conductance and a lower
biomass production as those measured for the non-drought-adapted type. The
non-drought-adapted type, in contrast, showed high water conductance
potential and a strong increase in ET rates when environmental conditions
became less constraining. With high rates even at dry conditions, this
community appears not to be optimized to save water and might experience
drought effects earlier and probably more strongly. As a result, the water
use efficiency of the drought-adapted plant community is with
2.6 gDW kg−1 of water much higher than that of the
non-drought-adapted plant community (0.16 gDW kg−1). In
summary, the vegetation's reaction to two covarying gradients of potential
evapotranspiration and soil water content revealed a clear difference in
vegetation development and between water-saving and water-spending strategies
regarding evapotranspiration.
Brief Communication: Mapping river ice using drones and structure from motion
Authors: Alfredsen Knut , Haas Christian , Tuhtan Jeffrey A. , Zinke Peggy
Published: February 2018

Abstract. In cold climate regions, the formation and break-up of river ice is important for river morphology, winter water supply, and riparian and instream ecology as well as for hydraulic engineering. Data on river ice is therefore significant, both to understand river ice processes directly and to assess ice effects on other systems. Ice measurement is complicated due to difficult site access, the inherent complexity of ice formations, and the potential danger involved in carrying out on-ice measurements. Remote sensing methods are therefore highly useful, and data from satellite-based sensors and, increasingly, aerial and terrestrial imagery are currently applied. Access to low cost drone systems with quality cameras and structure from motion software opens up a new possibility for mapping complex ice formations. Through this method, a georeferenced surface model can be built and data on ice thickness, spatial distribution, and volume can be extracted without accessing the ice, and with considerably fewer measurement efforts compared to traditional surveying methods. A methodology applied to ice mapping is outlined here, and examples are shown of how to successfully derive quantitative data on ice processes.
Decoupled simulations of offshore wind turbines with reduced rotor loads and aerodynamic damping
Authors: Schafhirt Sebastian , Muskulus Michael
Published: February 2018

Abstract. Decoupled load simulations are a computationally
efficient method to perform a dynamic analysis of an offshore wind turbine.
Modelling the dynamic interactions between rotor and support structure,
especially the damping caused by the rotating rotor, is of importance, since
it influences the structural response significantly and has a major impact on
estimating fatigue lifetime. Linear damping is usually used for this purpose,
but experimentally and analytically derived formulas to calculate an
aerodynamic damping ratio often show discrepancies to measurement and
simulation data. In this study decoupled simulation methods with reduced and
full rotor loads are compared to an integrated simulation. The accuracy of
decoupled methods is evaluated and an optimization is performed to obtain
aerodynamic damping ratios for different wind speeds that provide the best
results with respect to variance and equivalent fatigue loads at distinct
output locations. Results show that aerodynamic damping is not linear, but
it is possible to match desired output using decoupled models. Moreover,
damping ratios obtained from the empirical study suggest that aerodynamic
damping increases for higher wind speeds.
Space charge accumulation in XLPE versus temperature and water content
Authors: Andersen Ve Torbjørn , Mauseth Frank , Ildstad Erling
Published: February 2018

The rate of accumulation and amount of space charge is dependent on several factors, including the electrical properties of the insulation material and the temperature of the insulation. Increased water content has been found to increase the conductivity of XLPE up to three times compared to that of dry XLPE, and is therefore also expected to affect space charge accumulation.This paper presents results of space charge measurements on dry and wet 0.3 mm thick XLPE insulation at 20, 40 and 60 °C. The applied voltage was 10 kV, and the measurement period 14 days. Results show that increased water content leads to the formation of heterocharge at the cathode at 20 °C, as opposed to homocharge in case of a dry sample. At higher temperatures, increased water content mainly decreased the magnitude of accumulated charge.A conductivity-based sectioned model was introduced, and was used to recreate the changes in electric field set up by the accumulated space charge. Comparing the model with the measurements showed that conductivitybased charging was a central mechanism in space charge build-up. At higher temperatures, additional effects not covered by the model were present.
The Effect of DC Electro-thermal Ageing on Electrical Treeing in Polyethylene
Authors: Mantsch Adrian , Chen Xiangrong , Blennow Jörgen , Gubanski Stanislaw
Published: February 2018

Electrical treeing is among the main mechanisms responsible for electric breakdown in polymeric high voltage cables. In this paper, electrical treeing in electro-thermally aged low density polyethylene (LDPE) was evaluated by means of a real-time microscopic detection system. A wire – plane electrode test object with semiconducting tab was used in the study. The ageing was performed at a constant temperature of 80°C and an applied DC voltage of 10 kV of both polarities and lasted from 100 up to 800 hours. For testing the resistances to electrical treeing, tests were performed by applying 50 Hz AC voltage at a ramping speed of 0.5 kV/s. The obtained experimental results showed that mainly the thermal component of the ageing had an influence on electrical treeing parameters, namely on the initiation voltage as  well as the shape and occurrence frequency of the trees. With an increase of the ageing time, the tree inception voltage gradually decreased.
Thermal Ageing of XLPE Cable Insulation under Operational Temperatures – Does It Exist?
Authors: Olsen Rasmus , Holboell Joachim , Henriksen Mogens , Hagen Jens Z.
Published: February 2018

Thermal ageing of power cables may cause premature breakdown if the cables are operated at elevated temperatures, a relation usually described by Arrhenius’ law. The purpose of the present study is to investigate if any significant ageing takes place under normal operational temperatures. The investigation shows that thermal degradation at these comparably low temperatures is hardly reported and seems not to be of practical concern to transmission system operators. This may be the result of a conservative mind-set during the dimensioning of power systems, here in the case of power cables, which means that the lines are generally lightly loaded. Based on the literature found or, to be more precise, on the literature not found it seems to be very difficult to determine that thermal ageing should be problematic for operational power cables at all, in particular as compared to laboratory investigations at very high temperatures, where thermal ageing clearly takes place. To this conclusion contributes the fact that failure statistics do not correlate failures with severity of loading, and that the laboratory studies (which mosly conclude thermal ageing to be problematic) exposes the materials to unrealistic conditions.
Influence of antioxidants in epoxy-anhydride resin used for HV applications
Authors: Ho Chau Hon , Logakis Emmanuel , Krivda Andrej
Published: February 2018

In this work, various antioxidants with different chemical structures and functionalities were investigated in respect to their influence in the processibility and properties of a standard epoxyanhydride resin formulation used in HV applications. Such antioxidants are mainly used in thermoplastic materials as they are known for their long- and shortterm stabilizing effect against thermal and thermooxidative degradation. They are also used as UV stabilizers against decomposition and discoloration of the polymer and as metal deactivators by catching and eliminating metal ions. Recently, the use of such antioxidants as voltage stabilizers in cross-linked polyethylene has been reported showing a significant increase in breakdown voltage.Our investigations show that the processing requires additional mixing steps in order to completely dissolve antioxidants in the epoxy formulation. While little amounts of antioxidants or voltage stabilizers have a large influence in thermoplastics regarding thermal stability and electrical properties, the studied antioxidants in a concentration range of 1-5 weight-% show surprisingly only little impact in breakdown voltage as well as in dielectric properties and also in degradation behavior as detected by thermo-gravimetric analyses. Only the glass transition temperature of the cured epoxy resin is decreased in a few cases where the antioxidants have a plasticizing effect.
On-line condition monitoring importance and evolution
Authors: Fantana N.L.
Published: February 2018

In recent years there has been an increase in the availability of on-line condition monitoring devices and systems and of monitoring installations in utility networks. Their installation is judged considering a lot of factors including: general utility strategy, expected value from such an installation, asset and risk management, utility best practices, economic, environmental or regulatory pressures, and will vary from one utility to another. What is the present experience, the value from on-line condition monitoring and what are the opportunities and challenges in future grids and considering modern technologies? The paper intends also to position on-line condition monitoring in life strategies and point to evolution and international activities related to the topic.
Study of the Dielectric Response of Ester Impregnated Cellulose for Moisture Content Evaluation
Authors: Graczkowski A , Gielniak J , Przybyłek P , Walczak K , Morańda H
Published: February 2018

Knowledge about moisture content in impregnated cellulose insulation is essential for power transformers when estimating remaining lifetime, planning operating conditions and drying procedure. Frequency dielectric spectroscopy (FDS) is non-destructive, convenient method to asses moisture content of insulation. It is important to study dielectric response of ester-cellulose insulation due to growing number of transformers using synthetic ester MIDEL 7131 as insulation fluid [1, 2]. The paper presents study of dielectric response of synthetic ester-pressboard samples with various moisture content (from dry to 5%) measured in wide temperature range (from 5 ˚C to 50 ˚C). Measurement results for pressboard impregnated with synthetic ester are compared to data of pressboard impregnated with mineral oil. The aim of presented work is to provide patterns of dielectric response of synthetic esterpressboard for accurate moisture content evaluation.
Oil Aging due to Partial Discharge Activity
Authors: Ghaffarian Niasar M , Edin H , Clemence Kizza R
Published: February 2018

Oil is the main insulation in power transformers and over long time of ageing its insulation properties can change. In this paper ageing of oil due to the exposure to electric discharges was investigated. The effect of high energy discharges (complete arc) and low energy discharges (partial discharges) on oil properties such as breakdown strength and oil conductivity was investigated.An experimental setup consisting of two spherical electrodes was designed. The adjustable distance between the two electrodes made it possible to have PD with different magnitude.The oil conductivity and breakdown strength was measured for three sets of experiments. The first group of experiments was performed on new oil in order to have a reference for comparison. In the second group of experiments the new oil samples was exposed to 1000 and 3000 lightning impulses. In the third group of experiments new oil samples was exposed to partial discharge for different duration of time. Oil conductivity and breakdown strength of these aged samples were compared with new oil. The results show that after exposure to lightning impulse oil conductivity increases and breakdown strength decreases, However PD activity for short time does not change the oil conductivity but it reduces the breakdown strength.
Mechanical Simulations Regarding the Influence of Paper Insulation Degradation on the Radial Mechanical Strength of Continuously Transposed Conductors for Power Transformers
Authors: Geißler D , Liebfried T
Published: February 2018

The short circuit withstand capability of power transformers describes the ability of the windings to withstand electromagnetic forces resulting from current density in the conductors and magnetic stray fields. Especially operationally aged transformers often have a reduced short circuit strength what can lead to irreversible deformation of windings if high fault currents occur. Short circuit strength is to some degree dependent on the mechanical strength of the conductors. Mainly the cellulosic insulation materials experience degradation during operation time due to high temperatures and moisture. Hence a reduction in short circuit strength can be correlated to some degree with the aging of the cellulose. In this paper the influence of paper insulation around Continuously Transposed Conductors (CTC) on their mechanical strength will be analyzed by a simplified analytical model as well as by a FEA based mechanical simulation model.
Comparison of Test Setups for High Field Conductivity of HVDC Insulation Materials
Authors: Andersson Johan , Englund Villgot , Hagstrand Per-Ola , Friberg Andreas , Olsson Carl-Olof
Published: February 2018

Electrical conductivity is considered to be a key property for HVDC insulation. For cable insulation the conductivity level has to be sufficiently low in order to avoid a large leakage current that could cause heat generation in the insulation and contribute to additional transmission losses. The distribution of conductivity in the radial direction of the cable insulation dictates the distribution of electric field and space charge at steady state. It is therefore of interest to know the conductivity characteristics of insulation materials intended for HVDC cables.This paper presents a test method and procedure for evaluating the high field electrical conductivity of HVDC insulating materials and crosslinked polyethylene in particular. The results presented in this paper are generated from two nearly identical measurement setups using the same sample geometry, but installed in two different test facilities (ABB and Borealis). The results reveal that differences in conductivity can be seen; even between test setups with only minor differences and that the influence of sample preparation is crucial to obtain reproducibility. However, the decay of the measured current was observed to be relatively different between the measurement set-ups.
Mechanical Stress Distribution inside Dry Capacitor Elements
Authors: Petersson Linnea , Wei Kun , Paulsson Göran , Strömsten David , Ekh Johan
Published: February 2018

Many power products are produced by winding paper, polymer film or metal foils around an electrically active or passive core, like cables, bushings and capacitor elements. The mechanical stress distribution inside the product has high impact on its final performance. The stress distribution will be determined by the selected materials, winding parameters, and the ambient temperature. In this work the stress distribution inside dry metallized film capacitor elements for HV applications has been investigated using multiple experimental methods: Parotester, Smith needle, Pressure sensors and X-ray computed tomography. The results showed that the tested methods were unable to provide exact values of the radial stress distribution inside the capacitor element. As a continuation, the nonlinear material properties of the biaxially oriented polypropylene capacitor film were characterized. This work indicated that the temperature and the initial film stress will have an effect on the resulting tightness of the capacitor element.
Behavior of Rubber Materials under Exposure to High Electric Fields
Authors: Candela A. , Holboell J. , Henriksen M.
Published: February 2018

The effect of high electrical stress on rubber materials is investigated by performing breakdown tests and tracking resistance tests on selected samples. The study is focused on the relationship between the dielectric strength and the thickness of the samples, as well as the influence of the interfaces between different layers of material. Tracking resistance tests are also performed on the rubber material. The purpose is to provide a complete study of the applicability of the rubber material in thunderstorm environments.
Positive Breakdown Streamers and Acceleration in a Small Point-Plane Liquid Gap and Their Variation with Liquid Properties.
Authors: Linhjell Dag , Ingebrigtsen Stian , Lundgaard Lars , Unge Mikael
Published: February 2018

Positive breakdown streamers have been investigated in a short (5 mm) point-plane gap in cyclohexane and n-tridecane with and without the additives N,N-dimethylamine (DMA) with low ionization potential and azobenzene with a not quite as low ionization potential but a very low lowest excitation level. The effects off additives are fairly similar to what is known from longer gaps with DMA or pyrene added: the additives caused reduced breakdown voltage, significantly increased acceleration voltage and increased streamer velocity around breakdown. Molecule for molecule, azobenzene has less effect than DMA. The ratio between the acceleration and the breakdown voltage is significantly higher than in long gaps, though. Nonetheless, tests in short gaps are sufficiently good for screening (a large number of) liquid combinations.The two base liquids without additives, and also neat trichloroethene and DMA have been tested with and without a tube causing spatial restriction of the streamer. Restriction causes increased breakdown voltage and promotes the fastest streamer modes.
Axial Water Ingress MV XLPE Cable Designs with Watertight Barrier
Authors: Liland Knut Brede , Hellesø Svein Magne , Hvidsten Sverre , Bengtsson Karl Magnus , Ryen Arve
Published: February 2018

Humidity can enter the insulation system when the outer sheath of a cable becomes damaged. The relative humidity can then increase above a critical value (70 % RH), facilitating initiation and growth of water trees. The purpose of this experimental and numerical work is to determine how fast water vapour will diffuse axially in a soaked cable with a damaged outer sheath.Before drying (evacuation) relative humidity and temperature sensors were placed within the outer sheath at different axial positions. After the dryingprocess a hole was cut at the cable end facilitating water ingress. Numerical calculations of axial water diffusion were performed using Comsol.The numerical calculations show that the axial water vapour diffusion in the cable is slow and dependent of the air gap close to the swelling tape. After 430 days the measured humidity at 0.5 m had increased by about 75 % (initial 20%), and the sensor at 1 m had increased by 40%. Numerical calculations show a slower increase in the relative humidity. The actual axial liquid water penetration extensions, is yet not determined. The numerical calculations show that this is an important factor, as the calculations seem to be in more agreement with measurements when adjusting the position of the water front.
Modelling of Partial Discharges in Polymeric Insulation Exposed to Combined DC and AC Voltage
Authors: Olsen Pål Keim , Mauseth Frank , Ildstad Erling
Published: February 2018

This paper addresses the influence of an AC voltage superimposed on DC voltage on the partial discharge activity in artificial cylindrical cavities in polymer insulation. The main purpose was to investigate the feasibility of calculating the electric field distribution in such a configuration using a simple lumped parameter model. Two models for calculating the electric field have been compared, the lumped parameter classic
Analysis of the specific vibration modes of goethite (α-FeOOH) by terahertz spectroscopy and calculations of the vibration frequencies of a single molecule using density functional theory
Authors: Hasegawa Ryo , Kimura Takashi , Tanabe Tadao , Nishihara Katsuhiro , Taniyama Akira , Oyama Yutaka
Published: February 2018

Steel sheet with an insulator to prevent corrosion is used for various purposes including in building and car manufacture. Terahertz waves, for which insulators are highly permeable and metal surfaces are highly reflective, have been studied in order to establish a new inspection technology for these steel plates. In our previous research, spectroscopic measurements in the 1.0-4.0 THz range, generated by a GaP crystal, were carried out in order to collect information on the infrared activity of the metal corrosion products formed on Zn-Al hot-dip galvanized steel sheet. In the previous work, the infrared activity of Fe-based corrosion products was not examined. To examine these products, we conducted THz spectroscopy on goethite (α-FeOOH) in the range from 8.4 to 11.0 THz, generated by a GaSe crystal. The results of Attenuated Total Reflectance (ATR) FTIR spectral measurements and molecular vibration calculations were analyzed, on the basis of which the natural vibration modes of α-FeOOH in the THz frequency range were assigned.
Investigating Tertiary Level EFL Learners’ Willingness to Communicate in English
Authors: Basoz Tutku , Erten Ismail Hakki
Published: February 2018

The present study aimed to investigate Turkish EFL learners’ perceived levels of willingness to communicate (WTC) in English inside and outside the classroom. The study also aimed to explore whether there is a statistically significant difference between their in-class WTC in English and out-of-class WTC in English. The study, which employed a quantitative research design, was conducted with the participation of 701 EFL learners enrolled in the departments of Tourism Guidance and Tourism Management at Balıkesir University Faculty of Tourism located in Balıkesir, Turkey. The data collection instrument included a scale which measures the participants’ perceived levels of WTC in English. The data were analyzed descriptively through IBM SPSS 21. The findings of the study indicated that EFL learners have a moderate level of WTC in English. The findings also showed that there was a statistically significant difference between the participants’ perceived levels of their in-class WTC in English and their out-of-class WTC in English. It was found that they are more willing to communicate in English outside the classroom than they are inside the classroom. In the light of the findings, some practical recommendations were also noted.
ERM-Vroegsignalering opent de deur naar risicomanagementobservaties en dialoog met gedetineerden
Authors: Fluttert Frans , Eidhammer Gunnar
Published: February 2018

Risk management from observation to dialogue in prison services by means of the Early Recognition Method

Prison staff is exposed to aggression of prisoners which evokes work stress. In forensic psychiatry risk management principles, such as the Risk-Needs-Responsivity-model (RNR), assist staff to manage aggression by means applying risk management strategies. The Early Recognition Method (ERM) is such an evidence based strategy, developed and tested in forensic psychiatry. In ERM, staff gradually try to attune to aggressive behavior by means of the identification of early warning signs of aggression and systematically evaluated these in predetermined intervals. In this article it is explained and discussed how ERM could be applied meaningfully in prison services.
Suïcide bij gedetineerden in België: een dossierstudie
Authors: Favril Louis , Wittouck Ciska , Audenaert Kurt , Vander Laenen Freya
Published: February 2018

Suicide among prisoners in Belgium: a retrospective case-file study

Reducing the number of suicides in prison has been highlighted as an international priority. To date, however, studies examining prison suicides in Belgium are lacking. Therefore, adopting a retrospective record-based approach, we sought to investigate all suicides occurring in the whole Belgian prison estate during a 17-year period. The results underline the need for suicide prevention among prisoners in Belgium, and echo prior findings that restrictive preventive measures should be combined with psychosocial interventions in order to address the causes of prisoners being suicidal. Such strategies are ideally embedded within a comprehensive suicide prevention policy on a national level.
When Wanting the Best Is Bad
Authors: Fredericks Rachel ,   Department of Philosophy, Florida State University
Published: February 2018

Here I call attention to a class of desires that I call exclusionary desires. To have an exclusionary desire is to desire something under a description such that, were the desire satisfied, it would be logically impossible for people other than the desiring subject to possess the desired object. Assuming that we are morally responsible for our desires insofar as and because they reflect our evaluative judgments and are in principle subject to rational revision, I argue that we should, morally speaking, alter both social structures and our individual psychologies to minimize, or at least substantially reduce, exclusionary desires.
Comparing the awareness of and beliefs in sexually transmitted infections among university students in Madagascar and the United States of America
Authors: Reuter Peter R. , McGinnis Shannon , Reuter Kim E.
Published: February 2018

Young adults have a higher risk of contracting sexually transmitted infections (STIs) than other age groups. This risk may be mediated by their social and cultural setting which can impact young adults’ awareness of, beliefs in, and risk of contracting STIs (including HIV/AIDS). In order to understand how these factors vary among young adults of different cultures, it is important to study these issues on a cross-cultural scale. This study aimed to increase understanding of the relationship between the culture of a place of study and: (1) STI awareness; (2) belief in STIs; and (3) self-reported STI prevalence in the study population. Survey data were collected from university students in Madagascar (n = 242 surveys in 2013) and the United States of America (n = 199 surveys in 2015). Compared to students at the American university, students at the Malagasy university: (1) did not appear to have a conclusively lower awareness of STIs; (2) did not differ in rates of belief in the existence of gonorrhea and syphilis, but had higher rates of disbelief in HIV/AIDS; and (3) were more likely to report having been infected with syphilis and gonorrhea, but not with HIV/AIDS. Students at the Malagasy university also listed different reasons than the students at the American university for why they believed in the existence of STIs. These findings highlight the need for further cross-cultural research to better adapt intervention strategies to different cultural settings.
Structural snapshots along the reaction mechanism of the atypical poplar thioredoxin‐like2.1
Authors: Chibani Kamel , Saul Frederick , Didierjean Claude , Rouhier Nicolas , Haouz Ahmed
Published: February 2018

Plastidial thioredoxin (TRX)‐like2.1 proteins are atypical thioredoxins possessing a WCRKC active site signature and using glutathione for recycling. To obtain structural information supporting the peculiar catalytic mechanisms and target proteins of these TRXs, we solved the crystal structures of poplar TRX‐like2.1 in oxidized and reduced states and of mutated variants. These structures share similar folding with TRXs exhibiting the canonical WCGPC signature. Moreover, the overall conformation is not altered by reduction of the catalytic disulfide bond or in a C45S/C67S variant that formed a disulfide‐bridged dimer possibly mimicking reaction intermediates with target proteins. Modeling of the interaction of TRX‐like2.1 with both NADPH‐ and ferredoxin‐thioredoxin reductases (FTR) indicates that the presence of Arg43 and Lys44 residues likely precludes reduction by the plastidial FTR.
HIV‐1 gp41 transmembrane oligomerization monitored by FRET and FCS
Authors: Schroeder Sabrina , Kaufman Joshua D. , Grunwald Matthias , Walla Peter J. , Lakomek Nils‐Alexander , Wingfield Paul T.
Published: February 2018

The HIV‐1 envelope gp120/gp41 trimer mediates viral membrane fusion. After cluster of differentiation‐4 recognition, gp120 detaches from the virus, exposing gp41 which triggers fusion. During the fusion process, gp41 may not remain trimeric, which could have functional importance. Here, we probe the reversible association of full length gp41 (minus the cytoplasmic domain) in detergent micelles (with probes attached to transmembrane domain) by fluorescence resonance energy transfer (FRET) with a μm dissociation constant. This is compared with other methods. A gp41‐targeted fusion inhibitor must interfere with this transition, and monomeric, partially monomeric or trimeric states all present potential binding epitopes. The gp41 self‐association is a valid drug target model and FRET, a potential high‐throughput assay system, could be used to screen drug libraries.