bluuebunny/crossref_metadata_2025 huggingface dataset:
Landscape genomic analysis of candidate genes for climate adaptation in a California endemic oak, Quercus lobata
Authors: Sork Victoria L. , Squire Kevin , Gugger Paul F. , Steele Stephanie E. , Levy Eric D. , Eckert Andrew J.
Published: January 2016

PREMISE OF THE STUDY:

The ability of California tree populations to survive anthropogenic climate change will be shaped by the geographic structure of adaptive genetic variation. Our goal is to test whether climate‐associated candidate genes show evidence of spatially divergent selection in natural populations of valley oak, Quercus lobata, as preliminary indication of local adaptation.

METHODS:

Using DNA from 45 individuals from 13 localities across the species' range, we sequenced portions of 40 candidate genes related to budburst/flowering, growth, osmotic stress, and temperature stress. Using 195 single nucleotide polymorphisms (SNPs), we estimated genetic differentiation across populations and correlated allele frequencies with climate gradients using single‐locus and multivariate models.

RESULTS:

The top 5% of FST estimates ranged from 0.25 to 0.68, yielding loci potentially under spatially divergent selection. Environmental analyses of SNP frequencies with climate gradients revealed three significantly correlated SNPs within budburst/flowering genes and two SNPs within temperature stress genes with mean annual precipitation, after controlling for multiple testing. A redundancy model showed a significant association between SNPs and climate variables and revealed a similar set of SNPs with high loadings on the first axis. In the RDA, climate accounted for 67% of the explained variation, when holding climate constant, in contrast to a putatively neutral SSR data set where climate accounted for only 33%.

CONCLUSIONS:

Population differentiation and geographic gradients of allele frequencies in climate‐associated functional genes in Q. lobata provide initial evidence of adaptive genetic variation and background for predicting population response to climate change.
Determination of formation constants and structural characterization of cyclodextrin inclusion complexes with two phenolic isomers: carvacrol and thymol
Authors: Kfoury Miriana , Landy David , Ruellan Steven , Auezova Lizette , Greige-Gerges Hélène , Fourmentin Sophie
Published: January 2016

Carvacrol and thymol have been widely studied for their ability to control food spoilage and to extend shelf-life of food products due to their antimicrobial and antioxidant activities. However, they suffer from poor aqueous solubility and pronounced flavoring ability that limit their application in food systems. These drawbacks could be surpassed by encapsulation in cyclodextrins (CDs). Applications of their inclusion complexes with CDs were reported without investigating the inclusion phenomenon in deep. In this study, inclusion complexes were characterized in terms of formation constants (Kf), complexation efficiency (CE), CD:guest molar ratio and increase in bulk formulation by using an UV–visible competitive method, phase solubility studies as well as 1H and DOSY 1H NMR titration experiments. For the first time, a new algorithmic treatment that combines the chemical shifts and diffusion coefficients variations for all guest protons was applied to calculate Kf. The position of the hydroxy group in carvacrol and thymol did not affect the stoichiometry of the inclusion complexes but led to a different binding stability with CDs. 2D ROESY NMR experiments were also performed to prove the encapsulation and illustrate the stable 3D conformation of the inclusion complexes. The structural investigation was accomplished with molecular modeling studies. Finally, the radical scavenging activity of carvacrol and thymol was evaluated by the ABTS radical scavenging assay. An improvement of this activity was observed upon encapsulation. Taken together, these results evidence that the encapsulation in CDs could be valuable for applications of carvacrol and thymol in food.
Records of larentiine moths (Lepidoptera: Geometridae) collected at the Station Linné in Sweden
Authors: Schmidt Olga
Published: January 2016

The island of Öland, at the southeast of Sweden, has unique geological and environmental features. The Station Linné is a well-known Öland research station which provides facilities for effective studies and attracts researchers from all over the world. Moreover, the station remains a center for ecotourism due to extraordinary biodiversity of the area. The present paper is aimed to support popular science activities carried out on the island and to shed light on diverse geometrid moth fauna of the Station Linné.

As an outcome of several research projects, including the Swedish Malaise Trap Project (SMTP) and the Swedish Taxonomy Initiative (STI) conducted at the Station Linné, a list of larentiine moths (Lepidoptera: Geometridae) collected on the territory of the station is presented. Images of moths from above and underside are shown. Of the totally 192 species registered for Sweden, 41 species (more than 21%) were collected in close proximity to the main building of the Station Linné. Malaise trap sampling of Lepidoptera is discussed.
An online taxonomic database of the stick insect (Phasmida) egg-parasitising subfamilies Amiseginae and Loboscelidiinae (Hymenoptera: Chrysididae)
Authors: Baker Ed
Published: January 2016

The wasp subfamilies Amiseginae and Loboscelidiinae (Hymenoptera: Chrysididae) were last catalogued in Kimsey and Bohart (1991). The subfamilies are considered to be obligate egg parasitoids of the Phasmida (stick insects), which are known to be pests in many areas of the world (Baker 2015). Our lack of knowledge of these wasps, in particular their host associations and host specificity, prevents studies into using them as potential control agents for pest phasmids. Phasmids are popular throughout the world with people from a wide range of backgrounds, from pet keepers to professional entomologists.

A taxonomic database of the subfamilies Amiseginae and Loboscelidiinae has been created as the Chrysididae SpeciesFile, summarising the current state of scientific knowledge about these groups. In addition, a bibliography of works on these subfamilies has been created. In total information is provided for 187 valid species.
Le travail avec le couple en institution gériatrique
Authors: Charazac Pierre-Marie
Published: January 2016

À partir de son expérience de psychiatre attaché en ehpad , l’auteur commence par analyser les difficultés qu’ont les équipes gériatriques à travailler avec les couples sur la base du besoin de se protéger de l’excitation suscitée par couple réel et couple fantasmatique, puis du point de vue de l’exclusion du tiers absent, en opposant la permanence physique attendue des soignants à la présence symbolique du conjoint. Confrontant les modalités du deuil dans le couple et l’institution, il fait l’hypothèse que le couple serait porteur de ce que l’institution a besoin de se dissimuler pour survivre, le premier étant apte à traiter symboliquement l’absence et la mort tandis que la seconde tend à les ignorer ou les conjurer.
Einstein, la luz, el espacio-tiempo y los cuantos
Authors: Fernando Barbero G. J.
Published: January 2016

El estudio de la luz, su naturaleza y sus propiedades ocupó un lugar central en los trabajos de Albert Einstein. En este artículo se discute el papel de la luz en la formulación de la relatividad especial, en particular como instrumento para la definición operacional de las magnitudes cinemáticas básicas, se muestra su importancia para la comprensión de la relatividad general y, por último, se considera brevemente su comportamiento cuántico.
Du nouveau sur le poverello breton ?
Authors: de Cevins Marie-Madeleine
Published: January 2016

La figure de Jean Discalcéat, curé de paroisse au
diocèse de Rennes puis frère mineur à Quimper, mort de la peste en
1349, présente de larges zones d’ombres. Tout ce qui a été écrit à son
propos depuis le xviie siècle provient d’une Vita dont il ne subsiste
aucune mention ancienne et qu’une seule version écrite. Datée de 1613,
celle-ci est tenue pour la transcription fidèle d’un modèle médiéval
depuis sa découverte et son édition en 1910 par le postulateur général
de la cause de Jean Discalcéat en Curie. L’article propose de passer
le texte de la Vita au crible de l’analyse linguistique et
terminologique afin de s’assurer de son caractère authentiquement
médiéval. Il s’efforce dans un second temps de cerner le profil de son
auteur – qui semble appartenir à la mouvance spirituelle de l’Ordre
franciscain, à l’appui des suppositions formulées il y a vingt ans par
Jean-Christophe Cassard à partir d’une poignée d’indices. Enfin, il
tente de comprendre pourquoi la mémoire de Jean Discalcéat a été
oblitérée pendant plus de deux siècles, jusqu’à l’épanouissement de la
Contre-Réforme.
De la coordination au leadership : le rôle de l’animateur de cluster
Authors: Remoussenard-Pourquier Catherine , Ditter Jean-Guillaume
Published: January 2016

L’objet de cet article est d’éclairer les fonctions et compétences de l’animateur de cluster en mobilisant des concepts et outils du management stratégique et des ressources humaines. Contrairement aux clusters « spontanés » et auto-organisés, du type district industriel italien, les dispositifs encouragés par les pouvoirs publics requièrent des mécanismes de coordination spécifiques, généralement incarnés par un « animateur », qui n’a que peu été étudié par la littérature. La théorie du leadership redonne à l’animateur toute sa place en tant qu’acteur central des clusters volontaristes, avec une triple fonction : fédérer les acteurs par la confiance, manager les connaissances et les compétences, être un leader transformationnel du changement. Nous illustrons notre réflexion par l’analyse de trois exemples de clusters belges de l’écoconstruction.
Régulation des interactions au sein d’un réseau territorialisé d’entreprises dans le cadre de l’écologie industrielle
Authors: Beaurain Christophe , Varlet Delphine
Published: January 2016

En matière d’intégration des contraintes environnementales par les firmes, l’écologie industrielle est généralement présentée comme l’un des champs de réflexion et d’action les plus ambitieux. Elle repose sur la constitution et le développement de réseaux d’acteurs publics et privés reposant sur une interdépendance technique et sur l’élaboration d’objectifs communs. Nous essayons dans cet article de préciser le contenu de la dimension territoriale de ces réseaux, en insistant plus particulièrement sur les modalités de régulation des interactions entre les acteurs concernés. Nous nous appuyons pour cela sur l’expérience d’écologie industrielle menée au sein de l’agglomération de Dunkerque.
BIM and Prediction of Thermal Stability in Underroof Spaces
Authors: Jamnický Martin
Published: January 2016

Current increasing of costs for the acquisition of buildings causes effort to efficiently use all the space in these construction projects. The aim is therefore to make maximum use of under-roof space, both in new buildings and in buildings already standing. Because of the trend of construction with light wooden structures wrapped in thermal isolation, it is not easy to avoid summer overheating in under-roof spaces. For this reason, we’ve focused on optimizing building structures in terms of overheating in summer, so that additional costs for air conditioning were negligible or, ideally, non-existent. It is well known from our previous experience that there is smaller rise and fluctuation of indoor air temperature in rooms with heavy mass constructions (e.g. reinforced concrete, bricks, etc.) compared to rooms with light structures.
Analysis of the Influence of Thermal Characteristics of Simple Family House on Heat Use for Heating
Authors: Menďan Rastislav , Pavčeková Monika
Published: January 2016

The contribution shows an application of results of previous research regarding new method for more exact calculation of increase of thermal transmittance due to thermal bridges (ΔU-value) on a simple family house. The calculations and evaluations of thermal properties were carried out on ten variants of the selected simple family house.
The most Significant Factor Affecting the Calculation of Specific Heat Consumption for Heating for Family Houses According to STN 73 0540
Authors: Buday Peter
Published: January 2016

According to requirements of STN 73 0540-2, 2012 is defined the requirement to meet energy criteria using the specific heat consumption for heating as well as normalized value of specific heat consumption for heating with expectation of achieving of energy efficiency in buildings. These requirements are followed by springboard to legislative evaluation of buildings in terms of energy performance of building (promulgation 364/2012 Z.z.) – using of energy certificate.Although very significant aspect in this process is the way to implement complex environmental engineering, efficiency of the entire system, the heating medium, renewable energy, energy efficiency is the basis on specific heat consumption for heating. Paper is dealing with assessment of this parameter.
Theoretical Calculation of Thermal Transmittance
Authors: Palková Adela , Palko Milan
Published: January 2016

The article is focused on the theoretical calculation of thermal transmittance for new plastic window frame. Constant making the thermos-technical requirements stricter lays higher demands on improvement of window frames which the weakest element from the point of heat engineering. One important part of the window, which is needed to be improved, is a frame profile. Assessment of newly proposed window profile system is realised based on currently effective technical norms and regulations. The main aim of the theoretical assessment and computer simulation is to define the coefficient of passage of heat of the frame construction of a new plastic profile system.
Triple or Quadruple Glazing?
Authors: Chmúrny Ivan
Published: January 2016

Comparison of basic thermal insulation properties of triple glazing and quadruple glazing. It also compares the heat transfer coefficient of glazing, transmittance of solar radiation, the weight of glass and other basic properties of glazing. It deals with the effect of number and position of low-emission coating the quadruple glazing on the heat transfer coefficient. Reducing weight of quadruple glazing using thin heat-strengthened glass and dimensional constraints.
Measurement of Lightweight Experimental Wall and Comparison with Different Simulation Programs
Authors: Juras Peter , Ponechal Radoslav
Published: January 2016

This article deals with the long-term testing of experimental lightweight wall and comparison of the measurement with two different simulation software packages – WUFI and ESP-r in term of temperatures inside the fragments. Two lightweight timber-frame wall fragments with various outdoor coating colors were exposed to the real outdoor boundary climate conditions for four years. The indoor boundary conditions were secured as constant. In the wall fragments there are several built-in sensors.
Window Today – Still an Important Architectural Element of Exterior and Interior
Authors: Minarovičová Katarína
Published: January 2016

Is the window just one of the most commonplace elements of buildings? Is it a simple void or aperture in the external wall? It has to provide optical connection between interior and exterior admits light and air; offer a view, ensuring mental comfort in the interior. However, it is the most exposed element of the building envelope. Construction and building physic properties of windows significantly impact formation of optimal indoor climate and they are crucially involved in the energy loss of the object. Nevertheless, architectural expression is one of the most important functions of the window. As history of architecture shows, window is one of the key architectural components of a building.
Analysis and Evaluation of Moisture Factor, Reliability, Effectivity and Durability of Sanation Methods Used to Treat Damp Masonry
Authors: Držka Milan
Published: January 2016

The paper analyses and evaluates the factors that cause brickworks to wet. It shows the risk factors of single renovation methods as well. These risk factors determine the suitability of each method for excessive moisture elimination in brickwork.
Interaction of Building Thermal Technics with Building Aerodynamics in Problem Solving of Physical Cavities of Double-Skin Transparent Facades
Authors: Bielek Boris
Published: January 2016

The new facade technology of ecological, low-energy, cybernetic buildings. The physical theory of cavity. Quantification of the physical regime of corridor-type cavity of double-skin transparent facade with open circuit, employing the highly ecological self-recovery alternative source of solar energy. Aerodynamic quantification of cavity under the convection regime. Total aerodynamic resistance. Aerodynamic quantification of building. Aerodynamic coefficient of external pressure. The air rate of flow through the cavity under the wind pressure regime.
The Process of Hybridization in Sustainable Urban Residential Environment
Authors: Selcová Ľubica
Published: January 2016

By concentrating of suitable structure o heterogeneous functions into the hybrid residential complex we obtain a homogeneous whole. The combination of various architectural programs and functions in residential environment is creating a hybrid urban environment, which should bring higher quality of life for people in cities.
Experimental Pressure Measurement on Elliptic Cylinder
Authors: Franek Michal , Konecna Lenka , Hubová Oľga , Žilinský Juraj
Published: January 2016

This paper deals with pressure measurement on the surface of the elliptic cylinder. Aerodynamic properties are not same for different shape of the building. Therefore it is important complex experimental measurement for complicated shape. Aim of the article is to understanding the wind loads on building for various arrangements. Results are external pressure coefficients of elliptic model for various rotations. Conclusion of the experiment is to find optimal and critical wind direction for isolated building. This research will be background for future work of interference effect.
Atmospheric Boundary Layer
Authors: Vranková Andrea , Palko Milan
Published: January 2016

Atmospheric Boundary Layer (ABL) is the lowest part of the troposphere. The main feature of the Atmospheric Boundary Layer is the turbulent nature of the flow. The thickness of the boundary layer, formed by flowing air friction on the earth’s surface under various conditions move in quite a wide range. ABL is generally defined as being 0.5 km above the surface, although it can extend up to 2 km depending on time and location. The flow properties are most important over the surface of solid objects, which carry out all the reactions between fluid and solid.
Engineering Standards of Wind
Authors: Vranková Andrea , Palko Milan
Published: January 2016

Wind can be beneficial for example in seafaring, flying or energy production, as well as it can have negative impact. This negative effects can be prevented by deep analysis and experimental methods. Verification of buildings and structures on the model before implementation contributes to saving funds and also has an impact on the environment. In our country, the basic guide for assessing the effects of wind on the buildings is Slovak Technical Standard STN EN 1991-1-4, which provides guidance for determining wind loads in structural design of buildings. In the case of assessment of buildings that are beyond the scope of this standard, we can obtained by experimental measuring using wind tunnel or calculate it numerically, using some commercial software.
Influence of the Wind in Passages
Authors: Oleksakova Ivana , Magát Marek
Published: January 2016

This paper is concerned with wind influence on pedestrians in different buildings underpasses where with using of Computational Fluid Dynamic (CFD) is made study about proportion of buildings and underpasses affecting velocity and so pedestrian comfort in passage. For simulation of wind flow is used OpenFOAM software with k-epsilon model, which is in many papers represents as one of the best and most reasonable model for evaluation pedestrian comfort.
Modification of Watters’ Formula for Simple Aerated Concrete Walls
Authors: Pavčeková Monika , Menďan Rastislav
Published: January 2016

The contribution presents a mathematical modification of Watters’ formula used in modified Watters’ method. This formula expresses a dependence of sound reduction index on surface mass (mass law). On the basis of the previous research which resulted in the finding that the Watters’ method do not give acceptable results for simple walls from aerated concrete, the mentioned formula was modified to be usable for theoretical determination of sound reduction index of simple aerated concrete walls. The contribution also presents a modification of this formula for calculation of sound reduction index of simple aerated concrete walls with a plaster on both sides.
Mixed Reality in Architecture
Authors: Löffler Robert , Tholt Tomáš , Šimkovič Vladimír
Published: January 2016

Nowadays, strong influence of technology development in all areas of science and arts (architecture) can be observed. Therefore, it is not surprising that some of the contemporary topics in architectural discourse (particularly in the context of cutting edge technologies) are closely related to technology.
For example, new mixed reality devices coming to the commercial market belong to the area of research that is working with mixed realities and virtual spaces. Advantage of this technology is that it enables more dynamic and realistic perception of the computer designed world. Recent development and better accessibility of MR hardware has brought higher attention of designers to this problematic. Together with technology of games engines, the new powerful designing tool is emerging. The existence of this technology has an ability to transform design processes in the field of architecture.
The Optimization of Mechanized Earthwork Processes
Authors: Paulovičová Lucia
Published: January 2016

Earthwork processes are the most costly and time consuming component of construction these days and they are characterized by a powerful heavy mechanization which participate on the earthwork process. Current pressure for minimize the cost and maximize the productivity highlights the need to optimize earthworks. In this paper, the optimization process in the area of earthwork processes is described. The selection of the right types of machines for earthwork and its implements has become very difficult these days because of availability of variety of machines models and therefore a multicriteria method is presented to tackle the problem. This paper describes methodology for optimizing the earthwork process according to the selected optimal criteria. The methodology is focused on the proposal phase of optimization where the decision maker has to make a decision and choose the right type of excavators. To overcome the problem of comparing the chosen machines a mathematical modeling approach leading to multicriteria optimization was adopted to make the step wise decision. The methodology gives an mathematical models by which we can solve this problem.
Current Assisted Superplastic Forming of Titanium Alloy Bellows
Authors: Wang Guo Feng , Zhao Tao , Yang Mo , Zhao Xiang Yu
Published: January 2016

Titanium alloy bellows has advantages of light weight, excellent mechanical property, good heat resistance and corrosion resistance, etc. But the cold formability of titanium alloy is poor, so it is difficult to manufacture titanium alloy bellows by traditional mechanical forming and hydroforming. In this paper, current assisted superplastic forming technology was used to process titanium alloy bellows, which could overcome some shortcomings of traditional superplastic forming effectively, such as slow heating rate, high energy loss and low production efficiency. And titanium alloy bellows formed by this technology is of good quality with uniform wall thickness, light oxidation.
Mechanism of Low-Temperature Superplastic Deformation in Aluminum Alloys Containing a Dispersion of Nanoscale Al3(Sc,Zr) Particles
Authors: Kaibyshev Rustam
Published: January 2016

The ultrafine grained (UFG) structure with an average size of ∼0.8 μm was produced in an Al-Li-Mg-Sc alloy by equal-channel angular extrusion (ECAE) at 325oC with a total strain of ~16. Superplastic behavior was examined in the temperature range 150-250oC at strain rates ranging from 10-5 to 10-2 s-1. A maximum elongation-to-failure of 440% was recorded at 175oC (~0.5 Tm, where Tm is the melting point) and a strain rate of 2.8×10-5 s-1 with the corresponded strain rate sensitivity coefficient of 0.32. Mechanisms of low-temperature superplasticity (LTSP) and high-strain-rate superplasticity (HTSP) are essentially the same. The difference between superplastic behaviors at low and high temperatures is attributed to applied stress.
Characterization of a Superplastic Titanium Alloy with an Experimental and Numerical Approach Based on Free-Inflation Tests
Authors: Sorgente Donato , Piccininni Antonio , Piglionico Vito , Guglielmi Pasquale , Grossi Dario , Palumbo Gianfranco , Tricarico Luigi
Published: January 2016

It’s well known that the microstructure dramatically affects the strain behaviour of superplastic materials. Virtually, each batch should be characterized ex novo: optimal ranges of temperature and strain rate as well as material constants have to be defined. An accurate and simple characterization methodology based on a strain condition close enough to the real forming process is of great industrial interest. In this work, a characterization methodology based on an experimental and numerical approach is proposed. Experimental free inflation tests with a pressure jump were carried out on a titanium alloy. Results were used as reference data for an inverse analysis based on the height evolution of the dome. Material constants were calculated by means of a genetic algorithm. The approach was verified with further experimental results and a good correlation was found.
Superplasticity and Characterization of TIMETAL®54M Sheets
Authors: Kosaka Yoji , Gudipati Phani
Published: January 2016

TIMETAL®54M (Ti-5Al-4V-0.75Mo-0.5Fe) or Ti-54M is an alpha/beta titanium alloy developed by TIMET. Earlier technical publications have confirmed that laboratory scale Ti-54M sheets exhibit superior SPF capabilities compared to Ti-6Al-4V (Ti-64), in terms of flow stress, temperature and strain rate. Various gauges of these sheets, ranging from 0.64mm to 4.57mm, were produced on a production scale using TIMET patented process. Coupon tests were performed in accordance to ASTM E2448 and the results confirmed that the SPF capability of these sheets at a temperature as low as 774°C, which is a significant cost benefit in the SPF fabrications. The present paper discussed basic properties of Ti-54M sheets along with SPF coupon tests results showing lower temperature superplasticity. The low temperature superplasticity of Ti-54M is due to the combined effect of alloying elements and finer primary alpha particle size.
Improving the Microstructure and Mechanical Properties of a Cast Mg-9Al-1Zn Alloy Using Friction Stir Processing
Authors: Loke Wai Hoe , Ibrahim Raafat , Lathabai Sri
Published: January 2016

Friction stir processing (FSP) is a novel thermo-mechanical technique for modifying the microstructure of metals and alloys at targeted locations. In the present study, the microstructures and mechanical properties of friction stir processed Mg-9Al-1Zn (AZ91) alloy were evaluated. 4 mm thick sand cast AZ91 plates with a coarse dendritic microstructure and visible intermetallic phase were processed using single-pass FSP with different combinations of tool rotational and traverse speeds. Significant grain refinement (<10 μm), elimination of casting defects and the dissolution of intermetallic phase were observed at the stir zone (SZ) of all tested specimens. Microhardness tests showed increased microhardness along the SZ with a more uniform microhardness profile as compared to the regions outside the SZ. Mechanical properties evaluation using shear punch testing and subsequent microstructure analysis performed using scanning electron microscopy and microchemical analysis using Energy Dispersive Spectroscopy are discussed in this paper.
Deformation Characteristics of 6066 and 6069 Aluminum Alloys at Elevated Temperatures
Authors: Koizumi Shohei , Kobayashi Junya , Itoh Goroh
Published: January 2016

Currently liners of high-pressure hydrogen storage container for fuel cell vehicles are manufactured from the 6061 aluminum alloy pipes through spinning at elevated temperatures. Since the surroundings of the containers are reinforced with a large amount of high-cost CFRP, the use of 6066 or 6069 aluminum alloy with higher strength than 6061 is demanded to lower the cost of the container. However, the formability of these aluminum alloys at elevated temperatures has not been elucidated yet. In this study, tensile deformation characteristics of 6066 and 6069 aluminum alloys at temperatures ranging from 25 to 550°C were investigated. The total elongation of 6066 aluminum alloy was higher than that of 6069 aluminum alloy at 450°C. This may be caused by the lower volume fraction of constituent particles. The flow stresses of the two alloys were almost the same, and were decreased with increasing testing temperature. The increase in elongation and decrease in strength observed in the two alloys were attributable to dynamic recovery.
Tensile Properties of Recrystallized and Unrecrystallized Tungsten at Elevated Temperatures
Authors: Tano Nobuatsu , Kobayashi Junya , Itoh Goroh , Kurumada Akira , Mukae Shingo
Published: January 2016

Tungsten has higher melting point than any other metals. Therefore, tungsten is applied to the electrode for resistance welding. The electrodes for resistance welding of tungsten are mainly used for fusing joining because they have high heat resistance and are hard to be alloyed with work metal pieces. However, the cracks on electrode surface occur during cyclic welding processes. In this study, to reveal the relationship between the elevated temperature deformation characteristics and fracture mechanism of recrystallized and unrecrystallized tungsten, tensile tests were carried out with varying strain rate and testing temperature. At 400°C, the total elongation at a strain rate of 1.4×10-1 s-1 in the recrystallized tungsten decreased more than the total elongation at the other strain rate. At 600°C, total elongation increased by approximately 10%, if the strain rate was increased from 1.4×10-3 s-1 to 1.4×10-1 s-1. Then, the recrystallized tungsten at the strain rate of 1.4×10-1 s-1 had more necking than that of 1.4×10-3 s-1. The may be caused by an environmental embrittlement due to oxygen in the high temperature atmosphere.
Superplasticity of an AA2519 Aluminum Alloy
Authors: Zuiko Ivan , Gazizov Marat , Kaibyshev Rustam
Published: January 2016

A commercial AA2519 alloy with a chemical composition of Al-5.64Cu-0.33Mn-0.23Mg-0.15Zr (in wt. %) was subjected to two-step thermomechanical processing (TMP) providing the formation of fully recrystallized structure with an average grain size of ~7 mm in 3 mm thin sheets. Superplastic tensile tests were performed in the temperature interval 450-535°C and initial strain rates ranging from ~2.8 x 10-4 to ~6.0 x 10-1 s-1. The highest elongation-to-failure of ~750% appears at a temperature of ~525°C and an initial strain rate of ~1.4 × 10-4 s-1 with the corresponding strain rate sensitivity coefficient of ~0.46.
Effect of Natural Aging on RT and HSR Superplasticity of Ultrafine Grained Zn-22Al Alloy
Authors: Demirtas Muhammet , Purcek Gencaga , Yanar Harun , Zhang Zhen Jun , Zhang Zhe Feng
Published: January 2016

Zn–22Al alloy was processed using a well-designed two-step equal channel angular extrusion/pressing (ECAE/P), and ultrafine-grained (UFG) microstructure with 200 nm grain size was achieved. UFG Zn-22Al was subjected to long-term (up to 60 days) aging at room temperature (RT) and it was seen that natural aging caused limited grain growth in the microstructure. Grain sizes of about 300 nm, 350 nm and 350 nm were measured after 15, 30 and 60 days aging, which mean that UFG Zn-22Al alloy has a good microstructural stability at RT up to 60 days. ECAPed Zn-22Al alloy showed a maximum elongation of about 400% at a high strain rate of 5x10-2 s-1 and maximum elongation decreased with increasing grain size. Elongation to failures of ~375% and ~350% were obtained with the samples having 300 nm and 350 nm grain sizes, respectively. In addition, natural aging slightly decreased the strain rate at which superplastic region formed. While the maximum elongation occurred at the strain rate of 5x10-2 s-1 in ECAPed UFG alloy, it took place at lower strain rate of 1x10-2 s-1 after aging for all time periods. Also, flow stress of the alloy increased with increasing grain size during natural aging.
Experimental and Simulation Modeling of Nickel-Based Superalloy Pressure Welding Process
Authors: Galieva Elvina , Valitov Vener , Lutfullin Ramil , Dmitriev Sergey V. , Akhunova Angelina , Mukhametrakhimov Minnaul
Published: January 2016

The paper presents the results of finite element analysis of plastic deformation in the contact zone of dissimilar superalloys subjected to pressure welding. The results are compared for the two cases: with and without relief on the surfaces of parts to be welded. It is shown that the relief made on the surface can either decrease or increase the area of deformation stagnant zones, depending on the relief shape. The results of simulations are compared with the experimental test results.
Deformation Nanostructuring and Superplastic Processing of Metallic Materials
Authors: Utyashev Farid Z. , Mukhtarov Shamil Kh.
Published: January 2016

Theoretical and practical aspects of fabrication and processing of bulk metallic nanomaterials are presented. The effect of different deformation modes on the structure formation is shown. Development of nanotechnology with respect to fabrication of gas turbine engines (GTE) parts made of nanostructured superalloys is exemplified.
Nanostructuring of 2xxx Aluminum Alloy under Cryorolling to High Strains
Authors: Avtokratova Elena , Krymskiy Stanislav , Mikhaylovskaya Anastasia , Sitdikov Oleg , Markushev Michael
Published: January 2016

The structure transformations in the D16 (2024) aluminum alloy caused by isothermal rolling with effective strain up to e ~3.5 at a temperature of liquid nitrogen were investigated. It is shown that under straining to e ~2.0 the dislocation structure containing cells of the nanometric size is formed. At higher strains the dynamic recovery and continuous recrystallization result in the development of a mixed nano(sub) grain structure, which after e ~3.5 is characterized by the size and volume fraction of grains ~ 150 nm and 40-45%, respectively. Nature of the alloy structure transformations is discussed.
Improvement of Microstructure and Mechanical Properties of 7050-T7451 Aluminum by a Novel Double-Sided Friction Stir Processing
Authors: Yang Wen Jing , Li Ji Zhong , Wen Xue , Ding Hua
Published: January 2016

Recently, friction stir processing (FSP), as an effective tool, has been employed to modify microstructures and mechanical properties of metal sheet. A novel technique of double surface friction stir processing (FSP) was proposed in this study. A 7050-T7451 aluminum alloy sheet of 6.5mm in thickness was processed by FSP with 30% overlap in each side. The position deviation of the stir pin from the upper surface to the bottom surface is 35%. Significant grain refinement with an average grain size of 2.5μm from the as-received 50μm, can be obtained after double-sided FSP. In comparison with the conventional FSP, no HAZ (heat affected zone) or TMAZ (thermal mechanical affected zone) was formed between the adjacent stir zones of the aluminum alloy sheet. At a strain rate of 10-3 s-1, a maximum elongation of 29.8% and 327% in transverse direction of FSP passes have been achieved at room temperature and 400°C, respectively.
Low-Temperature Superplasticity in an Al-Mg-Sc Alloy Processed by ECAP
Authors: Yuzbekova Diana , Mogucheva Anna , Kaibyshev Rustam
Published: January 2016

The ultrafine grained structure of an AA5024 with an average size of ∼0.7 μm was produced by equal-channel angular pressing (ECAP) at 300°C with a total strain of ~12. Superplastic behavior of this alloy was examined in the temperature interval 175 - 300°C at strain rates ranging from 10-4 to 10-1 s-1. The maximum elongation-to-failure of ~1200% with the corresponding strain rate sensitivity coefficient, m, of ∼0.49 was attained at a temperature of 275°C and a strain rate of 5.6×10–3s–1. At 175°C (~0.53Tm, where Tm is the melting point), the elongation-to-failure of ~370% with the m value of ~0.3 was found at ε̇=1.4×10–4 s–1.
Direct Observation of Two-Dimensional Grain Boundary Sliding and Switching in ODS Ferritic Steel
Authors: Sato Eiichi , Masuda Hiroshi , Sugino Yoshito , Ukai Shigeharu
Published: January 2016

High-temperature tensile deformation was performed using an oxide-dispersionstrengthened (ODS) ferritic steel,, which has grain structure largely elongated and aligned in one direction, in the perpendicular direction. In the superplastic region II, two-dimensional grain boundary sliding (GBS) was achieved, in which the material did not shrink in the grain-axis direction and grain-boundary steps appeared only in the surface perpendicular to the grain axis. In this condition, a classical grain switching event was observed. Using kernel average misorientation maps drawn with SEM/EBSD, dominant deformation mechanisms and accommodation processes for GBS were examined in the different regions. Cooperative grain boundary sliding, in which only some of grain boundaries slide, was also observed.
Microtextural Changes and Superplasticity in an Al-7075 Alloy Processed by High-Pressure Torsion
Authors: Loucif Aicha , Huang Yi , Helbert Anne Laure , Baudin Thierry , Sabbaghianrad Shima , Langdon Terence G.
Published: January 2016

The influence of High-Pressure Torsion (HPT) on texture and superplasticity in an Al-7075 was studied using X-ray diffraction and tensile testing. The alloy was processed by HPT at room temperature under a pressure of 6.0 GPA up to a maximum of 20 turns. The pole figures were measured at mid-radius of the disks after 1, 5, 10 and 20 turns. The results show the presence of a typical torsion texture during HPT, in particular, the C{001}<110> component was found to develop preferentially. With increasing deformation, the A {111}<110> and the C components are reinforced after 5 turns and the texture tends to be random with the presence of a fibre texture near the center. Moreover, the fraction of C components tends to gradually decrease and a fairly isotropic microtexture is apparent after 20 turns. Tensile testing showed the development of excellent superplastic properties in this alloy with elongations up to ~700% when testing at a temperature of 623 K.
Heat Assisted Dieless Drawing Process of Superplastic Metal Microtubes - From Zn22Al to β Titanium Alloys
Authors: Furushima Tsuyoshi , Manabe Ken-Ichi
Published: January 2016

A heat assisted superplastic dieless drawing process that requires no dies or tools is applied to the drawing of a Zn-22Al and β titanium superplastic alloy for not only circular but also noncircular microtubes such as square, rectangular and noncircular multi core tubes having square inner and rectangular outer cross sections. As a result, the tendency has been to increase the limiting reduction in area with increasing strain rate sensitivity index m value. We successfully fabricate Zn-22Al alloy, AZ31 magnesium, β titanium circular microtubes with outer diameter of 191μm, 890μm and 180μm, respectively. Furthermore, a noncircular micro tube, which has inner square tubes with a 335μm side, and an outer rectangular tube of 533×923μm were fabricated successfully. During the dieless drawing process, the geometrical similarity law in cross section which the tube is drawn while maintaining its initial shape can be satisfied. The smooth surface can be obtained in case of superplastic dieless drawing process without contact situation with dies and tools. Consequently, it is found that the superplastic dieless drawing is effective for the fabrication of circular and noncircular multicore microtubes.
The Mechanics of Superplastic Forming - How to Incorporate and Model Superplastic and Superplastic-Like Conditions
Authors: Bylya Olga I. , Vasin R.A. , Blackwell Paul L.
Published: January 2016

Much work has been carried out in understanding the mechanics of superplasticity (SP). Some of the present challenges in SP forming revolve around the use of lower forming temperatures and faster strain rates, which may involve pushing the process boundaries to incorporate “superplastic-like” forming – perhaps also in materials with non-optimized microstructures. For process optimization there is a requirement to be able to model both within the SP and superplastic-like processing window in an integrated way. From a mechanics point of view the presence of high rate sensitivity is often seen as the key factor in controlling SP response. However, changes in phase distribution and grain morphology, or the accumulation of damage (cavitation) may compromise this assumption. The paper will examine the range of validity of some SP constitutive models and how they may be adapted to take into account processing routes that may incorporate superplastic-like and more conventional SP deformation modes.
Description of the Superplastic Flow Process by Deformation Mechanism Maps in Ultrafine-Grained Materials
Authors: Kawasaki Megumi , Langdon Terence G.
Published: January 2016

The synthesis of ultrafine-grained (UFG) materials is very attractive because small grains lead to excellent creep properties including superplastic ductility at elevated temperatures. Severe plastic deformation (SPD) is an attractive processing technique for refining microstructures of metallic materials to have ultrafine grain sizes within the submicrometer to even the nanometer level. Among the SPD techniques, most effective processing is conducted through equal-channel angular pressing (ECAP) and high-pressure torsion (HPT) and there are numerous reports demonstrating the improved tensile properties at elevated temperature. This report demonstrates recent results on superplasticity in metals after ECAP and HPT. Moreover, superplastic flow of the UFG materials is evaluated by using flow mechanisms developed earlier for coarse-grained materials and depicted by plotting deformation mechanism maps which provide excellent visual representations of flow properties over a wide range of testing conditions.
Effect of Sn Addition on Superplastic Properties of Zn-22mass%Al Eutectoid Alloy
Authors: Itoi Takaomi , Sato Fumiyasu , Takabayashi Yuki , Hirohashi Mitsuji
Published: January 2016

Superplastic behavior of a Zn 22 mass % Al eutectoid alloy (SPZ) with small addition of Sn (SPZSn) was investigated. Granular grain size of about 0.3 μm was obtained by water quench after annealing SPZ and SPZ05Sn (addition of 0.05 mass % Sn into the SPZ) at 653 K for 2 h. The fundamental microstructure of the SPZ05Sn was similar to that of the SPZ, but, microstructure observation by STEM showed additive Sn was present at the α’ grain boundary in the SPZ05Sn. Excellent high strain rate superplasticity was achieved in the SPZ05Sn, with elongation of more than 1300 % at 523 K at strain rate of 10-1 S-1. Furthermore, large elongation of about 1100 % was recorded at 473 K at strain rate of 10-1 S-1. The large elongation and high strain rate sensitivity value of the SPZ05Sn tend to shift to higher strain rate region as compared to those of the SPZ. It was considered that the small addition of Sn into the SPZ effectively suppressed the grain growth of α and β phase during the superplastic deformation, because granular grains less than 2 μm is maintained after superplastic deformation at 523 K.
Research of Solid Compound Formation during Thermal Deformation Effect on Intermetallic Ni3Al-Alloy with a Heat-Resistant Alloy EP975 and Influence on the Physical, Mechanical and Performance Properties
Authors: Valitov Vener , Povarova Kira , Bazyleva Olga , Drozdov Andrey , Ovsepyan Sergey , Galieva Elvina
Published: January 2016

The work is aimed at processing highly efficient one-piece units of gas turbine aircraft engines discs with blades (blisks) to exclude heavy locking joints and to reduce the weight of the units while improving their reliability. Intermetallic γ ́+γ alloys based on γ ́-Ni3Al phase of the VKNA type selected as blade material and Ni-based high alloy EP975 selected for discs have similar initial melting temperatures (~1340оС and~1300оC, respectively). Solid state joints (SSJ) EP975 //VKNA-mono are obtained at the homologous temperatures of 0.86-0.91 Tm (K).It is shown that the most efficient method for producing solid joints between the Ni3Al based intermetallic alloys and the EP975-type high-temperature nickel alloys is a solid state pressure welding in the conditions of high-temperature superplasticity; this technique has been developed in the IMSP RAS (grant RFBR No 130812200).
An Analysis of Superplastic Forming in a Re-Entrant Shape
Authors: Kumaresan G. , Kalaichelvan K.
Published: January 2016

Superplasticity is the ability of a polycrystalline material to exhibit, very large elongations without necking prior to failure in generally isotropic manner. Elongations in excess of 400% are usually referred to as Superplasticity. As the limitations of sheet metal fabrication are most often determined by the tensile ductility, superplasticity in sheet metals offers advantages for the forming of complex shapes easily as a regular production process.The focus of the present work is to arrive at the optimum process parameters in the superplastic forming in re-entrant shape of 7075 aluminium alloy, so as to achieve minimum thinning, lesser forming time and reduction in micro cavities.
Hot Forming and Superplastic Forming: Presses Evolution and New Applications in the Aerospace Industry
Authors: Sana Guillaume , Petiot Alain , Giraudet Arnaud
Published: January 2016

ACB (France) and its sister company Cyril Bath (USA) have a long experience in the fields of hydraulic presses and metal forming for the aerospace industry. This experience is particularly focused on the manufacturing of structural and engines parts. The purpose of this presentation is to show how the combination of both activities in the fields of Hot Forming/Sizing and Superplastic Forming results in continual progress and how recent evolution open new fields of applications. First, both processes will be shortly introduced. The advantages of Hot Forming, Superplastic forming and Diffusion Bonding technologies will be demonstrated regarding current customer’s requirements. To conclude an overview of on-going research programs will be made to present strong advantages of dual presses combining Hot Forming and Superplastic processes.
Topology Optimization and Process Validation of a SPF/DB Cylinder Structure
Authors: Shao Jie , Li Zhi Qiang , Xu Hui Yuan , Han Xiu Quan , Zhang Rong Xia
Published: January 2016

CAD models were built for a three-layer SPF/DB cylinder component. FEM method was employed to simulate the SPF/DB process with different girder structure at appropriate temperature/strain rate combinations. The results show that topology parameters of the structure influence the thickness of outer sheet and surface quality. When the thickness ratio of outer sheet to inner sheet exceeded 3:1 and the angle between adjacent ribs was great than 110 degree, ribs were formed and the cylinder surface was perfect. The simulation result was verified by experiment. The experimental results showed that the optimized cylinder structure can be formed at 920°C, 1×10-4 strain rate perfectly, and the size of blank cylinder diameter can be controlled accurately by SPF/DB mold and the size deviation is less than 0.5mm.