bluuebunny/crossref_metadata_2025 huggingface dataset:
HemoKinect: A Microsoft Kinect V2 Based Exergaming Software to Supervise Physical Exercise of Patients with Hemophilia
Authors: Mateo Fernando , Soria-Olivas Emilio , Carrasco Juan J. , Bonanad Santiago , Querol Felipe , Pérez-Alenda Sofía
Published: July 2018

Patients with hemophilia need to strictly follow exercise routines to minimize their risk of suffering bleeding in joints, known as hemarthrosis. This paper introduces and validates a new exergaming software tool called HemoKinect that intends to keep track of exercises using Microsoft Kinect V2’s body tracking capabilities. The software has been developed in C++ and MATLAB. The Kinect SDK V2.0 libraries have been used to obtain 3D joint positions from the Kinect color and depth sensors. Performing angle calculations and center-of-mass (COM) estimations using these joint positions, HemoKinect can evaluate the following exercises: elbow flexion/extension, knee flexion/extension (squat), step climb (ankle exercise) and multi-directional balance based on COM. The software generates reports and progress graphs and is able to directly send the results to the physician via email. Exercises have been validated with 10 controls and eight patients. HemoKinect successfully registered elbow and knee exercises, while displaying real-time joint angle measurements. Additionally, steps were successfully counted in up to 78% of the cases. Regarding balance, differences were found in the scores according to the difficulty level and direction. HemoKinect supposes a significant leap forward in terms of exergaming applicability to rehabilitation of patients with hemophilia, allowing remote supervision.
Comparison of Soil–Water Characteristic Curves in One-Dimensional and Isotropic Stress Conditions
Authors: Habasimbi Paul , Nishimura Tomoyoshi
Published: July 2018

Understanding unsaturated soil behavior is key to the design of foundations and embankment structures. Geotechnical engineers have applied net normal stress and matric suction to these engineering problems. Water retention activity in soils is used to predict seepage problems and stability of slope failures. Soil–Water Characteristic Curve (SWCC) tests contribute largely to matric suction interpretation. Determination of SWCCs in the laboratory is usually done using a pressure plate apparatus where vertical or confining stress cannot be applied. Mathematical models of SWCC though commonly accepted in geotechnical engineering practices, do not take into consideration stress conditions such as the difference between a one-dimensional condition and isotropic confining conditions. This study conducted SWCC tests of a silt soil under one-dimensional and isotropic confining stress conditions and focused on the differences between these types of SWCC data sets. Vertical and isotropic confining stresses ranging from 100 to 600 kPa were applied under both stress conditions. SWCCs appears to be affected by the influence of different stress conditions. Lateral pressure and confinement on an isotropic compression condition caused the soil specimen to become dense in void structure and consequently, soil moisture flow movement decreased. This probably induced high retention activities in the silt soil specimen. The study further suggests that the current SWCC models require further development to take into consideration the effect of different stress conditions.
Multi-Disciplinary Determination of the Rural/Urban Boundary: A Case Study in Xi’an, China
Authors: Fang Lei , Wang Yingjie
Published: July 2018

Rapid urbanization in China has blurred the boundaries between rural and urban areas in both geographic and conceptual terms. Accurately identifying this boundary in a given area is an important prerequisite for studies of these areas, but previous research has used fairly simplistic factors to distinguish the two areas (such as population density). In this study, we built a model combining multi-layer conditions and cumulative percentage methods based on five indicators linking spatial, economic, and demographic factors to produce a more comprehensive and quantitative method for identifying rural and urban areas. Using Xi’an, China as a case study, our methods produced a more accurate determination of the rural-urban divide when compared to data from the National Bureau of Statistics of the People’s Republic of China. Specifically, the urbanization level was 3.24% lower in the new model, with a total urban area that was 621.87 km2 lower. These results were checked by field survey and satellite imagery for accuracy. This new model thus provides local governments and other interested parties a theoretical and technological foundation for more accurate rural/urban planning and management in the future.
Non-Locality and Late-Time Cosmic Acceleration from an Ultraviolet Complete Theory †
Authors: Narain Gaurav , Li Tianjun
Published: July 2018

A local phenomenological model that reduces to a non-local gravitational theory giving dark energy is proposed. The non-local gravity action is known to fit the data as well as Λ-CDM thereby demanding a more fundamental local treatment. It is seen that the scale-invariant higher-derivative scalar-tensor theory of gravity, which is known to be ultraviolet perturbative renormalizable to all loops and where ghosts become innocuous, generates non-locality at low energies. The local action comprises of two real scalar fields coupled non-minimally with the higher-derivative gravity action. When one of the scalar acquiring the Vacuum Expectation Value (VEV) induces Einstein–Hilbert gravity, generates mass for fields, and gets decoupled from system, it leaves behind a residual theory which in turn leads to a non-local gravity generating dark energy effects.
Wave Climate at Shallow Waters along the Abu Dhabi Coast
Authors: Hamza Waleed , Lusito Letizia , Ligorio Francesco , Tomasicchio Giuseppe Roberto , D’Alessandro Felice
Published: July 2018

High-resolution, reliable global atmospheric and oceanic numerical models can represent a key factor in designing a coastal intervention. At the present, two main centers have the capabilities to produce them: the National Oceanic and Atmospheric Administration (NOAA) in the U.S.A. and the European Centre for Medium-Range Weather Forecasts (ECMWF). The NOAA and ECMWF wave models are developed, in particular, for different water regions: deep, intermediate, and shallow water regions using different types of spatial and temporal grids. Recently, in the Arabian Gulf (also named Persian Gulf), the Abu Dhabi Municipality (ADM) installed an ADCP (Acoustic Doppler Current Profiler) to observe the atmospheric and oceanographic conditions (water level, significant wave height, peak wave period, water temperature, and wind speed and direction) at 6 m water depth, in the vicinity of the shoreline of the Saadiyat beach. Courtesy of Abu Dhabi Municipality, this observations dataset is available; the recorded data span the period from June 2015 to January 2018 (included), with a time resolution of 10 min and 30 min for the atmospheric and oceanographic variables, respectively. At the ADCP deployment location (ADMins), the wave climate has been determined using wave propagation of the NOAA offshore wave dataset by means of the Simulating WAves Nearshore (SWAN) numerical model, the NOAA and ECMWF wave datasets at the closest grid point in shallow water conditions, and the SPM ’84 hindcasting method with the NOAA wind dataset used as input. It is shown that the best agreement with the observed wave climate is obtained using the SPM ’84 hindcasting method for the shallow water conditions.
Evidence of Intermediate-scale Energy Spectrum Anisotropy of Cosmic Rays E ≥ 1019.2 eV with the Telescope Array Surface Detector
Authors: Abbasi R. U. , Abe M. , Abu-Zayyad T. , Allen M. , Azuma R. , Barcikowski E. , Belz J. W. , Bergman D. R. , Blake S. A. , Cady R. , Cheon B. G. , Chiba J. , Chikawa M. , Matteo A. Di , Fujii T. , Fujita K. , Fukushima M. , Furlich G. , Goto T. , Hanlon W. , Hayashi M. , Hayashi Y. , Hayashida N. , Hibino K. , Honda K. , Ikeda D. , Inoue N. , Ishii T. , Ishimori R. , Ito H. , Ivanov D. , Jeong H. M. , Jeong S. , Jui C. C. H. , Kadota K. , Kakimoto F. , Kalashev O. , Kasahara K. , Kawai H. , Kawakami S. , Kawana S. , Kawata K. , Kido E. , Kim H. B. , Kim J. H. , Kim J. H. , Kishigami S. , Kitamura S. , Kitamura Y. , Kuzmin V. , Kuznetsov M. , Kwon Y. J. , Lee K. H. , Lubsandorzhiev B. , Lundquist J. P. , Machida K. , Martens K. , Matsuyama T. , Matthews J. N. , Mayta R. , Minamino M. , Mukai K. , Myers I. , Nagasawa K. , Nagataki S. , Nakamura R. , Nakamura T. , Nonaka T. , Nozato A. , Oda H. , Ogio S. , Ogura J. , Ohnishi M. , Ohoka H. , Okuda T. , Omura Y. , Ono M. , Onogi R. , Oshima A. , Ozawa S. , Park I. H. , Pshirkov M. S. , Rodriguez D. C. , Rubtsov G. , Ryu D. , Sagawa H. , Sahara R. , Saito K. , Saito Y. , Sakaki N. , Sakurai N. , Scott L. M. , Seki T. , Sekino K. , Shah P. D. , Shibata F. , Shibata T. , Shimodaira H. , Shin B. K. , Shin H. S. , Smith J. D. , Sokolsky P. , Stokes B. T. , Stratton S. R. , Stroman T. A. , Suzawa T. , Takagi Y. , Takahashi Y. , Takamura M. , Takeishi R. , Taketa A. , Takita M. , Tameda Y. , Tanaka H. , Tanaka K. , Tanaka M. , Thomas S. B. , Thomson G. B. , Tinyakov P. , Tkachev I. , Tokuno H. , Tomida T. , Troitsky S. , Tsunesada Y. , Tsutsumi K. , Uchihori Y. , Udo S. , Urban F. , Wong T. , Yamamoto M. , Yamane R. , Yamaoka H. , Yamazaki K. , Yang J. , Yashiro K. , Yoneda Y. , Yoshida S. , Yoshii H. , Zhezher Y. , Zundel Z.
Published: July 2018

Evidence for an intermediate-scale energy spectrum anisotropy has been found in the arrival directions of ultra-high energy cosmic rays for energies greater than 1019.2 eV in the northern hemisphere using 7 years of Telescope Array surface detector data. A relative energy distribution test is done comparing events inside oversampled spherical caps of equal exposure, to those outside, using the Poisson likelihood ratio. The center of maximum significance is at 9h16m, 45°, and has a deficit of events with energies 1019.2 ≤ E < 1019.75 eV and an excess for E ≥ 1019.75 eV. The post-trial probability of this energy anisotropy, appearing by chance anywhere on an isotropic sky, is found by Monte Carlo simulation to be 9 × 10−5 (3.74σ
global).
First ALMA Light Curve Constrains Refreshed Reverse Shocks and Jet Magnetization in GRB 161219B
Authors: Laskar Tanmoy , Alexander Kate D. , Berger Edo , Guidorzi Cristiano , Margutti Raffaella , Fong Wen-fai , Kilpatrick Charles D. , Milne Peter , Drout Maria R. , Mundell C. G. , Kobayashi Shiho , Lunnan Ragnhild , Duran Rodolfo Barniol , Menten Karl M. , Ioka Kunihito , Williams Peter K. G.
Published: July 2018

We present detailed multiwavelength observations of GRB 161219B at z = 0.1475, spanning the radio to X-ray regimes, and the first Atacama Large Millimeter/submillimeter Array (ALMA) light curve of a γ-ray burst (GRB) afterglow. The centimeter- and millimeter-band observations before 8.5 days require emission in excess of that produced by the afterglow forward shock (FS). These data are consistent with radiation from a refreshed reverse shock (RS) produced by the injection of energy into the FS, signatures of which are also present in the X-ray and optical light curves. We infer a constant-density circumburst environment with an extremely low density,

, and show that this is a characteristic of all strong RS detections to date. The Karl G. Lansky Very Large Array (VLA) observations exhibit unexpected rapid variability on roughly minute timescales, indicative of strong interstellar scintillation. The X-ray, ALMA, and VLA observations together constrain the jet break time,

days, yielding a wide jet opening angle of

, implying beaming-corrected γ-ray and kinetic energies of

erg and

erg, respectively. Comparing the RS and FS emission, we show that the ejecta are only weakly magnetized, with relative magnetization,

, compared to the FS. These direct, multifrequency measurements of a refreshed RS spanning the optical to radio bands highlight the impact of radio and millimeter data in probing the production and nature of GRB jets.
Heuschrecken (Orthoptera) in Biodiversitätsförderflächen der voralpinen Kulturlandschaft Schönenbergs (Schweiz, Kanton Zürich) mit Trends seit 1990
Authors: Schlegel Jürg , Schnetzler Stefan
Published: July 2018

Unsere Untersuchungen in der voralpinen Kulturlandschaft Schönenbergs (Schweiz, Kanton Zürich) haben ergeben, dass die Biodiversitätsförderflächen-Typen Streuefläche, Extensivweide und Extensivwiese im Vergleich zu konventionell bewirtschafteten Fettwiesen einen stark positiven Effekt auf die Diversität und Individuendichte von Heuschrecken ausüben. Innerhalb der Biodiversitätsförderflächen wiesen Heuschrecken in Streueflächen wiederum signifikant höhere Diversitätswerte und Individuendichten auf als in Extensivwiesen und Extensivweiden. Sie beherbergten zudem fast 95% aller beobachteten Individuen der Heuschrecken der Roten Liste. Innerhalb der Streueflächen war in Pfeifengraswiesen und Hochstaudenfluren eine signifikant höhere Heuschreckendiversität zu verzeichnen als in Kleinseggenrieden, Grossseggenrieden und verschilften Teilflächen. Die Individuendichten in Pfeifengraswiesen und Hochstaudenfluren erwiesen sich im Vergleich zu Grossseggenrieden als signifikant höher.

Im Vergleich zu früheren Erhebungen in Schönenberg ZH aus den Jahren 1990 und 2000 veränderte sich die Heuschreckendiversität in den Fettwiesen 2016 nicht signifikant, jedoch zeigten sich auf Artebene deutliche Verschiebungen der relativen Häufigkeiten. So kam die eher trockenheitsliebende Art Chorthippusbiguttulus in den Fettwiesen 2016 bedeutend häufiger vor als 1990 und 2000, während die in der Region eher feuchtigkeitsliebende Art Chorthippusdorsatus einen gegenteiligen Trend aufwies. Die 1990 und 2000 noch nicht beobachtete Art Chorthippusalbomarginatus fand sich 2016 in einigen Fettwiesen, welche zu den östlichsten Fundorten im Voralpenraum gehören.

In den Streueflächen wurde 2016 eine signifikant höhere Heuschreckendiversität als 1990 festgestellt. Die in der Schweiz gefährdete Art Conocephalusfuscus erlitt seit 1990 massive Einbussen, dafür nahmen andere Arten in ihrer relativen Häufigkeit markant zu, z.B. die potenziell gefährdeten Arten Chrysochraondispar und Decticusverrucivorus.

Zusätzliche Massnahmen zur Heuschreckenförderung werden erörtert, mit Schwerpunkt auf der asynchronen Nutzung, schonenden Mähtechniken sowie räumlich und zeitlich wechselnden Altgrasinseln.
Neodendryphiella, a novel genus of the Dictyosporiaceae (Pleosporales)
Authors: Iturrieta-González Isabel , Gené Josepa , Guarro Josep , Castañeda-Ruiz Rafael F. , García Dania
Published: July 2018

In a survey of soil and herbivore dung microfungi in Mexico and Spain, several dendryphiella-like species were found. Phylogenetic analyses based on ITS and LSU sequences showed that these fungi belonged to the family Dictyosporiaceae (Pleosporales) and represent an undescribed monophyletic lineage distant fromDendryphiella. Therefore, the genusNeodendryphiellais proposed to accommodate three new species,N.mali,N.michoacanensisandN.tarraconensis. The novel genus shares morphological features withDendryphiellasuch as differentiated conidiophores and polytretic integrated conidiogenous cells, that produce acropetal branched chains of conidia.Neodendryphielladiffers in the absence of nodulose conidiophores bearing conidiogenous cells with pores surrounded by a thickened and darkened wall, typical features in the conidiogenous apparatus ofDendryphiella. In addition, the phylogenetic and morphological analysis of several reference strains of differentDendryphiellaspecies, available for comparison, support the proposal ofD.variabilissp. nov., which mainly differs from the other species of the genus by having conidia up to 7 septa and highlight thatD.vinosaandD.infuscansare obscure species that require further taxonomic review.
Two new species of the bamboo-feeding genus Bambusicaliscelis Chen & Zhang, 2011 from China (Hemiptera, Fulgoromorpha, Caliscelidae)
Authors: Gong Nian , Yang Lin , Chen Xiang-Sheng
Published: July 2018

Two new species of the bamboo-feeding planthopper genusBambusicaliscelisChen & Zhang, 2011,B.flavusChen & Gong,sp. n.andB.guttatusChen & Gong,sp. n., are described and illustrated from China. The generic characteristics are redefined and photographs of the new species are provided. A checklist and a key to species ofBambusicaliscelisare also given.
A critical evaluation of the exotic bird collection of the Šariš Museum in Bardejov, Slovakia
Authors: Mikula Peter , Csanády Alexander , Hromada Martin
Published: July 2018

A collection of exotic birds deposited in the Šariš Museum in Bardejov (SMB), Slovakia, has not been evaluated critically since their deposition. We assessed the accuracy of identification of 465 bird specimens deposited in SMB with native distributions outside of Slovakia. Specimens belonged to 322 species of 82 families and 26 orders. Of the specimen represented, 34 belonged to species considered as ‘near-threatened’ (7.3%), 16 as ‘vulnerable’ (3.4%) and one as ‘endangered’ (0.2%). The SMB collection holds 10 of 28 extant Cuban endemic species and another 11 species endemic to the Caribbean archipelago. Even among birds that are relatively easy to identify, many specimens were identified incorrectly or species identification was missing. Of 465 specimens evaluated, 95 (20.4%) were identified incorrectly or were missing species identification, and another 79 (17%) were identified correctly, but their names have changed over time due to taxonomic shift, thus they required correction.
Fraud Crime Mitigation of Mobile Application Users for Online Transportation
Authors: Damaini Amaya Andri , Nugroho Ginanjar Setyo , Suyoto Suyoto
Published: July 2018

Online transport service is currently popular in Indonesia. Not only provide ride-sharing service, but also other services such as food delivery, medicine delivery, and courier service. Ease of use and low cost make online transportation service more favored by consumers. However, this service has several disadvantages that cause inconvenience to the user until the occurrence of fraud action by the driver or the customer. Therefore identification of system deficiencies needs to be done to improve the security and convenience of customer and drivers of online transport services. This paper will analyze the problems of online transportation services applications through cases that have occurred and complaints of users of online transport applications. Through this analysis, we propose solutions to protect consumers and drivers for the security of transactions.
The Design of Notification System on Android Smartphone for Academic Announcement
Authors: Sanmorino Ahmad , Fajri Ricky Maulana
Published: July 2018

Through this article, we try to propose the design of notification system that runs on the Android operating system. This notification will be used for the academic announcement in the campus environment. The current announcement system only depends on the web portal, phones, groups in social media or short message system. The use of web portals and phones still has many limitations. Our proposed notification system can meet the needs of academic announcement broadcast quickly and massively. In the end, this will cut the cost that stakeholders need to operate the academic announcement system in the campus environment. The design of smart notification system that we proposed in the future will be integrated with the academic information system.
The Effect of Teaching Mathematical Problems Solving Through Using Mobile Learning on the Seventh Grade Students' Ability to Solve them in Jordan
Authors: Al-Khateeb Mohammad Ahmad
Published: July 2018

The study aimed to probe the effect of solving mathematical problems through using Mobile Learning (ML) on the seventh grade students' ability to solve them in Jordan. The study sample consisted of fifty-four (54) students of seventh basic grade in Zarqa in Jordan who were divided into two groups randomly: experimental group which included twenty-six (26) students who were taught through using mobile learning methodology and control group which consisted of twenty-eight (28) students who were taught through using the traditional ways of teaching. Mathematical problem solving test were prepared which were verified to check their validity and reliability. In general, the results related to problem solving and its dimensions revealed the understanding and reading of the problem, setting forth a plan for solving and implementing it as well as revising the solution). The students of the experimental group were taught by using mobile learning methodology were more excellent than their counterparts in the control group who were taught through using traditional teaching.
Superplastic Deformation Behavior of As-Received and Hydrogenated Ti2AlNb Alloy
Authors: Li Xi Feng , Jia Guo Peng , Cao Xu Dong , Chen Jun , Wu Guo Hong
Published: July 2018

In this paper, the effects of temperature and initial strain rate on the superplasticity of as-received Ti2AlNb alloy were studied by uniaxial tensile tests. Temperature from 870°C to 1030°C with an interval of 40°C and initial strain rate range of 10-2s-1to 10-4s-1were selected. The optimal superplasticity of 190.3% was obtained at 990°C with initial strain rate of 10-3s-1. The superplastic properties were deteriorated at 1030°C due to serious grain coarsening. In order to improve superplastic properties, the as-received alloy was hydrogenated with different hydrogen contents. It was found that hydrogen addition can significantly decrease flow stress and increase elongation. A higher elongation occurs at 910°C in hydrogenated alloy.
Superplasticity of Friction-Stir Welds of Zr-Modified 5083 Aluminum Alloy with Ultrafine-Grained Structure
Authors: Mironov Sergey , Malopheyev Sergey , Vysotskiy Igor , Kaibyshev Rustam
Published: July 2018

The commercial Zr-modified 5083 aluminum alloy was homogenized to precipitate nanoscale Al6Mn particles and then undergone to equal-channel angular pressing (ECAP) at 300 °C to a true strain of ~12 via BC route. The obtained ultrafine-grained material was subjected to friction-stir welding (FSW). The welding variables were selected to provide reasonable homogeneous microstructure distribution across the weld zone and thus to ensure a highly uniform elongation during subsequent superplastic tests of the joints. Superplastic behavior of the obtained welds is discussed.
Molecular Dynamics Simulation of Nonequilibrium Grain Boundaries in Ultrafine-Grained Nickel and their Relaxation under Cyclic Loading
Authors: Nazarov Ayrat A. , Murzaev Ramil’ T.
Published: July 2018

Atomistic simulations of the structure, energy and relaxation under the action of high frequency cyclic straining are carried out for columnar nickel nanocrystals with [112] column axis, the grain boundaries (GBs) of which are in a nonequilibrium state caused by the presence of extrinsic grain boundary dislocations (EGBDs). A special method of introducing EGBDs is used to create initial structures with nonequilibrium GBs. Energy of GBs as a function of the degree of nonequilibrium is evaluated and qualitatively compared to the results of dislocation and disclination modeling. It is shown that under loading by symmetrically oscillating stresses the nonequilibrium GBs generate lattice dislocations, which travel across the grains and are absorbed by opposite GBs thus resulting in a relaxation of the structure, long-range stress fields and the energy of GBs.
Effect of Different Initial Lamellar Plate Thicknesses on Grain Refinement and Superplastic Behaviour in HPT-Processed Ti-6Al-4V Alloy
Authors: Huang Yi , Muzy Jessica , Bazarnik Piotr , Lewandowska Małgorzata , Langdon Terence G.
Published: July 2018

Ti-6Al-4V alloy was heated to above the β phase transformation temperature with two different cooling speeds: air cooling and furnace cooling, in order to generate a full thin lamellar structure and a fully coarse lamellar structure, respectively. Then the alloy in two heat-treated conditions was processed at room temperature up to 10 turns by high-pressure torsion (HPT) processing. Investigations were carried out to study the effect of the different initial lamellar plate thicknesses on the microstructure development during HPT processing, and the corresponding superplastic behaviour at the selected low testing temperatures of 773 - 923 K.
Comparative Study of the Ultrafine-Grained Structure 316L Stainless Steel and Ti-6-4 Alloy Produced by Selective Laser Melting
Authors: Shakirov Ivan , Zhukov Anton , Kuznetsov Pavel , Staritsyn Mikhail
Published: July 2018

Selective laser melting (SLM) of powders is a promising technology to produce part with complex shape. The structure features is of great interest for many researches because metallic materials produced by SLM technology demonstrate rather high mechanical properties. Thanks to the ultra-fast crystallization during SLM process, the created parts should have an ultrafine grained or amorphous structure. Based on the obtained data, it can be concluded that the observed ultrafine-grained structure and crystalline anisotropy can be arised from the rapid motion of the laser beam, resulting in significant temperature gradients and high cooling rates. Formation of dendritic and columnar microstructure is typical for crystallization processes occurring at high temperature gradients. In the present study the EBSD maps, crystalline structure features of the 316 austenitic stainless steel and titanium alloy Ti-6-4 are presented. The dependencies of the mechanical properties on the specific energy input during SLM process are discussed. The main assumption is that during SLM it is possible to produce metallic material with subgrain structure 0.7 – 0.9 mcm, which is promising for further investigation of superplasticity.
Mechanical Properties of Multi-Directional Forged Al-7Si-4Zn-3Cu Alloy
Authors: Alemdağ Yasin , Karabıyık Sadun , Yanar Harun , Pürçek Gençağa
Published: July 2018

In this study, Al-7Si-4Zn-3Cu alloy was processed by multi-directional forging (MDF) at 3, 6 and pass corresponding one, two and three cycle, respectively. The structural and mechanical properties of the alloys were investigated at as-cast, homogenised and MDF states. The MDF resulted in a severely deformed and refined microstructure with eliminated casting defects like micro-porosity and formation of nearly homogeneous distributed finer silicon particles. The tensile (UTS) and yield (YS) of the alloy increased up to two cycle, above which they showed a decrease, while the percent elongation increased continuously as the cycle number increased. The comprehensive strength and micro and macro hardness of the alloy decreased with increasing MDF cycles. The results were evaluated according to microstructural changes depending on MDF cycles.
Evaluation of Wear Resistance of Copper at Sliding against TiC Based Coatings under Load
Authors: Mukanov Samat , Bychkova Marina , Kudryashov Alexander , Petrzhik Mikhail
Published: July 2018

An evaluation of the adhesion interaction of copper and TiC-based coatings formed by electrospark deposition using TiC based electrodes (SHIM mark) was carried out. Tribological tests of the samples were carried out using Pin-on-Disk testing machine. It is established that the least (0.07) coefficient of friction has a electrospark coating deposited of electrode material contained tungsten additives. After tests on the optical profilometer, it was found out that some coatings do not have adherence of the wear products of the copper counterbody. So, it was found two different types of interaction of the copper counterbody with the coatings - with adherence and without adherence (so called wear less sliding behavior) which is perspective to develop novel deforming tools.
Effect of ECAP Prior to Aging on Microstructure, Precipitation Behaviour and Mechanical Properties of an Al-Cu-Mg Alloy
Authors: Zuiko Ivan , Gazizov Marat , Kaibyshev Rustam
Published: July 2018

Microstructure, precipitation behaviour and mechanical properties of an Al-5.64Cu-0.33Mn-0.23Mg-0.14Zr-0.11Ti (in wt. %) alloy subjected to thermomechanical processing (TMP) involving equal-channel angular pressing (ECAP) at ambient temperature to total strains (ε) of ~1 and ~2 followed by aging at 180°C for 0-28 h have been investigated and compared with conventional aging at the same temperature (T6 state). TMP led to significant increase in yield stress (YS) and ultimate tensile strength (UTS) and decrease in elongation-to-fracture as compared to the peak-aged T6 state. The YS, UTS and δ values attained after ECAP to ε ~ 2 followed by peak ageing were ~510 MPa, ~540 MPa and ~7.6%, respectively. The changes in mechanical properties were related to microstructure evolution and precipitation behaviour. TMP conditions obtaining a high-strength state of the Al-Cu-Mg alloy are discussed.
Microstructure and Mechanical Properties of an Ultrafine Grained Medium-Mn Steel
Authors: Torganchuk Vladimir , Molodov Dmitri A. , Belyakov Andrey , Kaibyshev Rustam
Published: July 2018

The effect of cold working followed by annealing on the development of ultrafine grained microstructure and mechanical properties of an Fe-12%Mn-0.6%C-1.5%Al medium-manganese steel was studied. The steel was cold rolled with intermediate annealings and then annealed at 873 K or 923 K for 30 min. The yield strength and total elongation of the Fe-12Mn-0.6C-1.5Al steel after cold rolling were 1200 MPa and 14%, respectively. The heat treatments resulted in the formation of two phase (austenite-ferrite) ultrafine grained microstructures with average grain sizes of 0.9 to 1.2 μm, depending on the annealing temperature. The annealed ultrafine grained steel samples exhibit the yield strength in the range of 800-950 MPa, the ultimate tensile strength in the range of 1150-1200 MPa, and total elongation of 12% to 19%.
Analysis of the Evolution of Mechanical Properties of Metallic Materials by AMD-Methods for Thermomechanical Impacts
Authors: Migel Irina Anatolievna , Kustov Aleksander Igorevich
Published: July 2018

One of the topical material science problems today is the problem of analyzing the evolution of the mechanical properties of metallic materials, predicting their behavior under thermomechanical influences. To solve this problem, it is suggested to use methods of acoustomicrouscopy flaw detection or AMD-methods [1]. They make it possible to obtain, with the aid of acoustic waves (AB), images of the structure at various depths from the surface of the object. This does not require any additional surface treatment, including chemical etching. The advantages of analyzing the evolution of the mechanical properties of alloys using AMD methods are related to the fact that acoustic waves and their characteristics are sensitive both to the parameters of the structural elements and to their changes associated with external influences.
Annealing Behavior and Kinetics of Primary Recrystallization of Copper
Authors: Morozova A. , Dolzhenko A. , Odnobokova M. , Zhilyaev Alexander P. , Belyakov Andrey , Kaibyshev Rustam
Published: July 2018

The microstructure evolution during the annealing treatment of a recycled copper after cold rolling to total strain of 2.6 was investigated. The cold deformation resulted in the elongation of initial grains along rolling direction and the strain-induced formation of subboundaries. Annealing recovery occurred in the temperature range 100-250 °C. The recrystallized microstructures were observed after annealing at 300-400 °C. The hardness of partially recrystallized copper samples was interpreted in terms of dislocation strengthening. The recrystallization kinetics was estimated according to a Johnson–Mehl–Avrami–Kolmogorov equation using different methods for recrystallized fraction determination, i.e., the fractional softening, the grain orientation spread, and the Kernel average misorientation.
Effect of Pre-Straining Method on Mechanical Properties of Thermo-Mechanically Processed Al-Cu-Mg Alloy
Authors: Zuiko Ivan , Kulitckii Vladislav , Kaibyshev Rustam
Published: July 2018

The present study deals with the effect of pre-deformation technique of AA2519 alloy (Al–5.64Cu–0.33Mn–0.23Mg–0.15Zr–0.11Ti–0.09V–0.08Fe–0.01Si (wt. %)) under T8 tempers, on condition that intermediate strains are equal. After undergoing T87 by pre-stretching and peak ageing the alloy demonstrates the yield stress, ultimate tensile strength and elongation to failure of 425.4±2.4 MPa, 475±2.4 MPa, 12.1±0.4%, respectively. The 7% pre-straining by rolling leads to-5% decrease in yield stress, practically the same ultimate tensile strength and-20% decrease in ductility. This effect can be ascribed to more homogeneous distribution of dislocations which act as heterogeneous nucleation sites for the θ′-phase precipitation. In addition to precipitates of the Al–Cu family (θ′′ and θ′), Ω-phase plates on {111}α habit plane was observed. The effect of pre-straining prior to ageing on the precipitation behavior and its relation with mechanical properties of the AA2519 is considered.
Solution Treatment Process of Haynes 230 Cylindrical Blank Used for Hot Flow Spinning
Authors: Xu Xiao , Li Ze Yu , Xiao Gang Feng , Xia Qin Xiang
Published: July 2018

Hot flow spinning is one of the most effective methods to manufacture the cylindrical parts of nickel-based superalloy. However, crack occurs easily in the hot flow spinning process of Haynes230 alloy when the cylindrical blanks are obtained by forging and wire-electrode cutting billet due to the severe segregation of carbides existed in the microstructure of the Haynes230 forging billet. The solution treatment process of Haynes230 blank is put forward to obtain the cylindrical blank with homogeneous and fine grained microstructure used for hot flow spinning. The influence of solution treatment process on the microstructure and hardness of Haynes 230 was investigated; and the relationship between grain size and solution temperature was analyzed. The results show that the grain size of Haynes230 alloy increases with the increasing of solution temperature and the holding time. The abnormal growth of grains occurs under excessively high solution temperature and long holding time. The grain growth activation energy of Haynes230 is about 296.0kJ/mol. The hardness of Haynes230 alloy decreases with the increasing of solution temperature, but negligibly changes with the holding time. The severe segregation of carbides can be eliminated and the cylindrical blank with homogeneous and fine grained microstructure used for hot flow spinning of Haynes230 alloy can be obtained after solution treatment at 1230°C for 60 min heat preservation.
Numerical and Experimental Investigation on the Hybrid Superplastic Forming of the Conical Mg Alloy Component
Authors: Guo Mei Ling , Tan Ming Jen , Song Xu , Chua Beng Wah
Published: July 2018

Hybrid superplastic forming (SPF) is a novel sheet metal forming technique that combines hot drawing with gas forming process. Compared with the conventional SPF process, the thickness distribution of AZ31B part formed by this hybrid SPF method has been significantly improved. Additionally, the microstructure evolution of AZ31 was examined by electron backscatter diffraction (EBSD). Many subgrains with low misorientation angle were observed in the coarse grains during SPF. Based on the tensile test results, parameters of hyperbolic sine creep law model was determined at 400 oC. The hybrid SPF behavior of non-superplastic grade AZ31B was predicted by ABAQUS using this material forming model. The FEM results of thickness distribution, thinning characteristics and forming height were compared with the experimental results and have shown reasonable agreement with each other.
Simulation and Experiment Investigation on Superplastic Forming/Diffusion Bonding Process of a Ti-6Al-4V Alloy Rear Fuselage Part
Authors: Guo Gui Qiang , Li Dong Sheng , Li Xiao Qiang , Huang Xuan Zhao
Published: July 2018

Superplastic forming/diffusion bonding (SPF/DB) process is widely used in aviation titanium alloy parts forming. PAM-STAMP was utilized to simulate the SPF/DB process of a Ti-6Al-4V double layer structure part in rear fuselage at 920°C and reach the thickness distribution of the part. Then the part was formed based on simulation. The thickness distribution of the practical part was measured and compared with the simulation result. The results show that the thickness distributions of practical and simulated part fit well with each other.
Influence of Oblique Edge Blanking on the Online Punching Quality after Stretch Bending
Authors: Xia Qin Xiang , Xu Teng , Bo Hu , Zhang Hong Chen , Fratini Livan
Published: July 2018

The oblique edge punching was proposed to reduce the surrounding sag failure occurred under the large punching force during online punching after stretch bending. The finite element models under three different kinds of punches were stablished and the punching processes were simulated by using the DEFORM-3D software. Comparison between the flat-edge punch and the oblique edge punches were realized, and the optimal height of the oblique edge of the unilateral bevelled punch and the single-peak bevelled punch were obtained. Three kinds of punches were designed based on the simulation results, and the experiments for manufacturing the upper strip of the automobile door frame by the online punching after stretch bending were carried out. The results show that the depth of the surrounding sag of punching can be reduced significantly and the appearance quality can be improved effectively by the oblique edge blanking. The effect to reduce the depth of surrounding sag failure by the unilateral bevelled punch is better than that by the single-peak bevelled punch, and the depth of surrounding sag failure on the side near the edge tip of the unilateral bevelled punch is smaller than that on the side away from the edge tip.
Characterization of Stress-Strain Behavior of Superplastic Titanium Alloy by Free Bulging Tests with Pressure Jumps
Authors: Aksenov Sergey A. , Sorgente Donato
Published: July 2018

The work is dedicated to determination of stress-strain behavior of Ti6Al4V alloy deformed in conditions of biaxial tension provided by free bulging testing. The dome height during each test was continuously measured and recorded using a magnetostrictive position transducer. All the tests were performed using stepped pressure regime with jump pressure changing between two values at evenly spaced time moments. This experimental technique provides the possibility to study strain rate sensitivity index variation during the test and subsequently construct strain and strain rate dependent material model. The output data of each test include the evolution of dome height, subsequent pressure regime and final thickness of the specimen at the dome pole. In the framework of this study the processing of such data in order to evaluate the material behavior is discussed. Inverse analysis with different material models was implemented as well as special direct technique allowing one to construct stress-strain curves based on the results of free bulging tests with pressure jumps. The obtained material model was verified by finite element simulation.
Simulation of Deformation Behavior and Microstructure Evolution during Hot Forging of TC11 Titanium Alloy
Authors: Alimov Artem , Zabelyan Dmitry , Burlakov Igor , Korotkov Igor , Gladkov Yuri
Published: July 2018

Finite element method is the most powerful tool for development and optimization of the metal forming processes. Analysis of titanium alloy critical parts should include the prediction of microstructure since their mechanical and technological properties essentially depend on the type and parameters of the microstructure. The technological process of parts production for aerospace applications is multi-operational and consists of deformation, heating and cooling stages. Therefore, it is necessary to simulate the microstructure evolution to obtain high quality parts. In presented paper FE simulation coupled with microstructure evolution during hot forging of TC11 titanium alloy has been performed by QForm FEM code. Constitutive relationships, friction conditions and microstructure evolution model have been established using the experiments. The kinetics of phase transformations has been described by the Johnson-Mehl-Avrami-Kolmogorov (JMAK) phenomenological model. The approach is illustrated by industrial case study that proved its practical applicability and economic advantages for technology development of titanium alloy critical parts.
Arrhenius-Type Constitutive Equation Model of Superplastic Deformation Behaviour of Different Titanium Based Alloys
Authors: Mosleh Ahmed O. , Mikhaylovskaya Anastasia V. , Kotov Anton D. , Portnoy Vladimir K.
Published: July 2018

Modelling and predicting the flow behaviour of metallic materials subjected to superplastic deformation is mandatory for providing useful information about the metal forming process. This information helps the designers to reduce the manufacturing time and costs by choosing appropriate deformation conditions based on the models results. The study developed a constitutive model to predict the flow behaviour of various Ti-based alloys (Ti-2.5Al-1.8Mn, Ti-6Al-4V and Ti-4Al-1V-3Mo) at elevated temperatures. The constant strain rate tests within the superplastic temperature and the strain rate ranges for each alloy were performed. The experimental tensile tests results were used to develop the hyperbolic sine Arrhenius-type constitutive models for each alloy. The performance of the developed model for each alloy was evaluated regarding the correlation coefficient (R), the mean absolute relative error (AARE) and the root mean square error (RMSE). The results revealed that the predicted flow stresses have a good agreement with the experimental flow stresses for the studied alloys.
Effect of Ultrasonic Treatment on the Characteristics of Superplasticity of Titanium Alloy Ti-6Al-4V
Authors: Samigullina Asiya , Murzinova Mariya , Mukhametgalina Aygul , Zhilyaev Alexander P. , Nazarov Ayrat A.
Published: July 2018

Effect of ultrasonic treatment (UST) with an amplitude of oscillating tension-compression stresses 100 MPa on the characteristics of superplastic deformation of Ti-6Al-4V alloy with an ultrafine grained (UFG) structure processed by equal-channel angular pressing (ECAP) is studied. During tensile tests at 600°C with initial strain rates in the interval from 10-4 to 10-3 s-1, ultrasonically irradiated samples exhibit a reduced flow stress, higher values of the strain rate sensitivity coefficient and elongation to failure as compared to the samples tested directly after ECAP. Detailed studies of the microstructure of samples subjected to ECAP only and ECAP followed by UST revealed no considerable differences. It is suggested that the UST affected fine structure of the material bringing them to a state with a higher ability of relaxation of deformation-induced defects.
On Dynamic Superplasticity of Aluminum Alloys with Initial Varying Grain Size Structure
Authors: Kitaeva Daria A. , Rudaev Yakov I. , Rudskoy Andrey I. , Kodzhaspirov Georgii E.
Published: July 2018

In the submitted paper there is a speech about mathematical modeling of behavior of group of the industrial aluminum alloys with initial varying grain size structure showing superplastic properties in certain temperature and strain rate ranges. Superplasticity of dynamic type are caused by simultaneous action of deformation rates and structural (phase) transitions of evolutionary type in open nonequilibrium systems. The association of deformation process with metal flow, that has irreversible structural and phase transition of indistinct type at one of the stages, allows to use synergetic approach. The experimental study of deformation behavior of group commercial aluminum alloys with initial varying grain size structure in the wide temperature and strain rate ranges (not only in case of superplasticity, but also in the boundary fields of thermoplasticity and high-temperature creep.) has led to creation of the mathematical model formulated from positions of mechanics of solid for simple tensile and compression. At the same time the offered model contains analytically formulated conditions for transition of material to a superplastic state. With using of the theory of elasto-plastic processes of small curvature the developed mathematical model is generalized for combined stress for technological problems of volume forming with use of superplasticity for the purpose receiving a semi-finished product with fine-grained structure.
Effect of Homogenization Treatment on Superplastic Properties of Aluminum Based Alloy with Minor Zr and Sc Additions
Authors: Kishchik Anna , Mikhaylovskaya Anastasia V. , Kotov Anton D. , Portnoy Vladimir K.
Published: July 2018

Effect of one-step and two-step homogenization treatment on precipitation of Al3(Sc,Zr) dispersoids, grain structure after annealing of cold rolled sheets and superplastic behaviour of a novel Al-Mg based alloy were studied. Heterogeneous nucleation of Al3(Sc,Zr) phase on dislocations and subboundaries dominated at one-step annealing and both homogeneous and heterogeneous nucleation of Al3(Sc,Zr) were observed at two-step annealing modes. It was shown that two-step treatment mode provides high density of Al3(Sc,Zr) precipitates and 650 % of elongation at the constant strain rate of 10-2 s-1 in the studied alloy.
Tensile Properties of AZX612 Magnesium Alloy Sheets Processed by Friction-Assisted Extrusion
Authors: Kobune Satoshi , Itoh Goroh
Published: July 2018

Tensile properties at room and elevated temperatures of AZX612 alloy sheets processed by a kind of lateral extrusion method namely Friction-Assisted Extrusion (FAE) were investigated. The FAE was developed to control the texture, and carried out at temperatures ranging from 250 to 350°C with an extrusion ratio of 4 from the as-rolled condition. The results showed that FAE changes the basal texture of the as-rolled sheet into that inclined by about 15˚ against the extrusion direction and raises the intensity of the texture. It was observed that the significant microstructure refinement from as-rolled condition of 10.8μm to 4.7μm after FAE due to dynamic recrystallization at the extrusion temperature of 250°C. The 0.2% proof stress of the FAEed sheets at room temperature became significantly smaller than that of the as-rolled sheet in the extrusion direction but became larger in the transverse direction, resulting in the larger anisotropy. This can be understood by the activity of basal slip. The anisotropy of the tensile properties disappeared at a temperature of 300°C and an initial strain rate of 3.3×10-4s-1. In addition, the elongation was improved from 72% of the as-rolled sheet to 152% at maximum of the FAEed sheets in the extrusion direction. This improvement was attributable to superplastic flow based on grain boundary sliding.
Normal and Resonant Raman Spectra of CuPc-MWCNT Blend
Authors: Ngah Demon Siti Zulaikha , Sa'aya Nurul Syahirah Nasuha , Ahmad Poad Nursaadah , Jamal Siti Hasnawati
Published: July 2018

Understanding molecular electronics is critical in advance of organic devices. Intermolecular interaction between copper phthalocyanine (CuPc) and multi-walled carbon nanotubes (MWCNT) was studied using infrared spectroscopy and confocal Raman microscope. The organics were prepared using solution processing method at ambient atmosphere. The infrared spectrum showed the signal from the lower wavenumber was largely dominated by broad absorption and the lacking of ‘fingerprints’ peaks provided no information on the MWCNT. Raman absorption spectra under normal (λ = 532 nm) and resonant (λ = 633 nm) were obtained to tackle the disadvantages in the former method. Fingerprint peaks of CuPc in frequency of 600 - 1600 cm-1 emerged under both excitation wavelengths. New 480 cm-1, 1100 cm-1 and 1300 cm-1 peaks were found in resonant spectra. There were no strong evidence of presence and interaction between CuPc and MWCNT detected in these measurements possibly due to overlapping vibrational states between the two compounds and insufficient quantity of MWCNT in the sample.