bluuebunny/crossref_metadata_2025_split huggingface dataset:
The analysis of algebra creative thinking skill based on strong mathematical habit of mind
Authors: Nugroho S W P , Riyadi  , Triyanto  
Published: June 2020

Abstract
This research aimed to describe the student’ creative thinking skill of two variables on linear equations system viewed from the strong mathematical habit of mind. The indicators of creative thinking skill include fluency, flexibility, and novelty. This research was a qualitative descriptive study. The subjects of this research were 7 students of IX A class at SMP N 4 Playen Gunungkidul. The data collection methods were a questionnaire, test, and interview to discover the students who had strong mathematical habit of mind. The research instruments had been validated by using triangulation method. The result showed that there were 2 students (2 8.58%) conformed with fluency indicator (it was categorized as less creative), there was 1 student (1 4. 2 8 °%o) conformed with flexibility indicator (it was categorized as adequate creative), and there were 4 students (5 7. 1 4°%o) namely 3 students conformed with fluency and flexibility indicator and student conformed with the indicators of fluency and novelty (it was categorized as creative). The analysis showed that the students who had strong mathematical habit of mind still there in the students who had less creative. There was no students who had strong mathematical habit of mind in the students who had very creative thinking skill. This was caused by the difficulty of students in turning contextual questions into mathematical sentences and lack of confidence in using various ways to solve the problems. The students tended to use some procedural steps in solving the problems. Therefore it was necessary to emphasize a good understanding of algebra concept and the practice of varying questions so that the students were not mistaken in using algebraic concepts and had no difficulty in solving non-routine algebraic questions.
Students’ mathematical communication abilities in solving geometry problems viewed from learning styles
Authors: Sholihah A N , Riyadi  , Triyanto  
Published: June 2020

Abstract
The purpose of this research is to describe student mathematical communication abilities in solving the problem of material transformation (reflection and rotation) in terms of student learning styles. This research is a qualitative descriptive study. The subjects consisted of 6 classes of IX students in Wonogiri 7 Junior High School who were selected by purposive sampling. Data collection tools used were written tests of communication abilities and questionnaires to categorize students based on their learning styles and interviews. The data validity of the data used triangulation method. Analysis of this data shows that the communication of visual students can meet indicators: 1) Reflecting and answering about mathematical concepts; 2) Connecting daily news with language mathematics symbols; 3) Expressing and evaluating into mathematical theory; 4) Using mathematical opinions to make detailed conjectures. The mathematical communication of the auditory students can meet the indicators: 2) Connecting daily news with language mathematics symbols; 3) Expressing and evaluating into mathematical theory; 4) Using mathematical opinions to make detailed conjectures. The mathematical communication of kinesthetic students can meet indicators: 1) Reflecting and answering about mathematical concepts; 3) Expressing and evaluating into mathematical theory. This shows that dominant students have mathematical communication abilities with visual learning styles caused by students who were being able to communicate their mathematical ideas connected in their daily lives.
Investigation of the students’ number sense in seventh grade
Authors: Marga S A , Kusmayadi T A , Fitriana L 
Published: June 2020

Abstract
2013 curriculum is the latest center of attention, especially in emphasizing the students’ understanding in learning mathematics not just only counting. The students understanding especially about these numbers can be seen from the students’ ideas to solve a problem. The students’ skills in solving the problem can be seen from their sensitivity to the numbers. This number sense ability can help the students’ performance by using some strategies that are useful for solving problems. Therefore, this study aimed to know the extent of number sense component possessed by VII H students at SMPN 3 Ponorogo. The subjects in this research were 30 students. The data collection used in this research was written number sense test result. This research was a qualitative descriptive study. The data that was obtained in this research such as the description of students’ number sense. The results indicated the ability of students based on component number sense, the lowest component number sense in recognizing the relative size of number and the students’ ability to decide wisely the strategies used from the calculation results. Overall, the average of students’ numbers sense was 50.78. Thus, it could be concluded that the ability of number sense that possessed by VII H students could be categorized as medium. However, the results of students’ work were still dominated by procedural understanding. The often problem faced by students were the lack knowledge about numbers concepts, the students used procedural ways, and the students did some errors in calculations.
Mathematical connections ability of junior high school students viewed from mathematical resilience
Authors: Rohmah S , Kusmayadi T A , Fitriana L 
Published: June 2020

Abstract
The mathematical connections ability is the ability to link between topics in mathematics, between mathematics with other disciplines and between mathematics and life. This study discusses about designing mathematical connection skills in terms of students’ mathematical resilience involving 31 students 8th grade students as research subjects. The method used in this research is descriptive method using qualitative. The research instruments used were mathematical resilience questionnaires and essay tests. The results of this study indicate for students who have high resilience, student success in recognizing and using relationships between mathematical ideas (70.31%), students’ success in understanding the relationship of mathematical ideas (80.15%), and student success in recognizing and applying one mathematical content to another mathematical content (83.33%). Students who have moderate resilience, student success in recognizing and using relationships between mathematical ideas (48.04%), students’ success in understanding the relevance of mathematical ideas (40.28%), and student success in recognizing and applying one mathematical content to another mathematical content (40.28%). Students who have low resilience, student success in recognizing and using relationships between mathematical ideas (35.94%), student success in understanding the relationship of mathematical ideas (39.71%), and student success in recognizing and applying one mathematical content to another mathematical content (37,5%).
The SOLO taxonomy: classify students’ responses in solving linear program problems
Authors: Claudia L F , Kusmayadi T A , Fitriana L 
Published: June 2020

Abstract
The aim of this study is to classify students’ responses in solving mathematical problems. Using the taxonomy by Biggs and Collis in 1982, called taxonomy is SOLO (Structure of Observed Learning Outcomes). In the SOLO taxonomy, there are five levels of students’ responses, such as pre-structural, uni- structural, multi-structural, relational, and extended abstract. Every student has different abilities, one of the ability is to understand mathematical concepts because sometimes students make misconceptions that result in students not being able to solve mathematical problems correctly. The concept in a linear program problem is that students can change story problems into mathematical modeling after that student can solve with the procedures that have been learned. This study used descriptive qualitative research and the selected of subjects is senior high school students in the City of Kediri and then used purposive sampling techniques. One of the chosen class consisting of 35 students was selected 5 students to represent each level of SOLO Taxonomy. The results from this study are: (1) Pre-structural level: Students cannot process information properly, (2) Uni-structural level: Students do not make the most of available information, (3) Multi-structural level: Students understand one concept which is example with variables and can model mathematics, (4) Relational level: Students can process information appropriately, and (5) Extended abstract level: Students can understand concepts well. With the levels of students’ response can be known to what extent students understand mathematics so they can solve mathematical problems.
NanoSQUIDs based on Nb nanobridges
Authors: Rodrigo R. , Faley M.I. , Dunin-Borkowski R.E. 
Published: June 2020

Abstract
We have developed nanoSQUIDs with Josephson junctions in the form of Nb nanobridges, whose thickness, width and length are in the order of the superconducting coherence length in Nb thin films, which is 15 nm at 4.2 K in 20-nm-thick films. The thin Nb films were deposited using pulsed DC magnetron sputtering. A 30-nm-thick mask of PMMA resist was formed by electron beam exposure using a dose of 50 mC/cm2 at 100 kV, at which PMMA operates as a high-resolution negative resist. Compared to the previously used HSQ resist, PMMA has a much better availability, lower health risk, a longer shelf life and a simpler development procedure, while maintaining sufficient resolution. Both Nb nanobridges with widths down to 10 nm and nanoSQUIDs with the incorporated nanobridges were fabricated using reactive ion etching with pure SF6 gas. They show non-hysteretic I(V)-characteristics and a modulation of the critical current at both directly injected or externally applied magnetic field fluxes. The obtained spin sensitivity of

S
n

1
/
2

≅
135

μ
B

/
√
H
z

is very promising for the use of the nanoSQUIDs as magnetic field sensors for the investigation of nanoscale objects.
Optimal SQUID Loop Size in Arrays of HTS SQUIDs
Authors: Crété Denis , Lemaître Yves , Marcilhac Bruno , Recoba-Pawlowski Eliana , Trastoy Juan , Ulysse Christian 
Published: June 2020

Abstract
Arrays of Superconducting interference devices (SQUIDs) deserve much attention for high frequency magnetic field detection because of the combined advantages of wideband radiofrequency operation and improved dynamic range compared to single SQUID magnetometers. Indeed, in principle the dynamic range should scale as the square root of the number of SQUIDs. It is well-known that the size of a SQUID designed for magnetometry has an optimum resulting from a trade-off between large magnetic flux in its loop and small loop inductance. Among the factors affecting this optimum when using arrays of SQUIDs, we discuss the impact of Josephson junction characteristic dispersion, experimentally observed with high temperature superconductors (HTS) and wideband requirement. Both limit the SQUID size to lower values, in particular for arrays of SQUIDs connected in series.
Design, Performance and Cabling Analysis of Nb3Sn Wires for the FCC Study
Authors: Hopkins Simon C , Baskys Algirdas , Bordini Bernardo , Fleiter Jerome , Ballarino Amalia 
Published: June 2020

Abstract
The hadron collider proposed by the Future Circular Collider (FCC) study would require high-field superconducting magnets capable of producing a dipole field of around 16 T in a 50 mm aperture. To develop a suitable conductor for these magnets, CERN is coordinating a conductor development programme aiming to obtain Nb3Sn wire with a non-copper critical current density of 1500 A mm−2 at 16 T and 4.2 K, in lengths suitable for manufacturing 14 m long magnets, and able to withstand cabling without significant degradation. Here we report the superconducting characterisation and quantitative microscopy of recently-developed Nb3Sn wires with novel layouts and compositions, and evaluate their suitability for Rutherford cabling based on cabling trials and rolling studies. An analysis of the influence of wire layout, materials and mechanical characteristics on cabling performance is presented, to support recommendations for future wire designs.
Microwave investigation of pinning in Te- and cubic-BN- added MgB2
Authors: Alimenti A. , Torokhtii K. , Grigoroscuta M. , Badica P. , Crisan A. , Silva E. , Pompeo N. 
Published: June 2020

Abstract
MgB2 has great potential for many applications, thanks to its relatively high critical temperature and low fabrication cost. Large efforts are done to improve the current carrying capabilities of bulks and tapes in view of different application fields, e.g. with the addition of Te and cubic-BN to MgB2. To elucidate the vortex pinning physics exploiting a different dynamic regime, we present here a microwave study of the pinning properties of spark plasma sintered bulk MgB2 with and without the addition of 0.01 % at. Te or cubic-BN. We show the surface resistance Rs
of the MgB2 samples measured with a dielectric-loaded resonator at ~ 16.5 GHz and ~ 26.7 GHz in the 10 K-Tc temperature range at fields up to 1.0 T. Then, the MgB2
Rs
is studied with high frequency vortex motion models in order to obtain the pinning constant (Labusch parameter) and the depinning frequency. Finally, the microwave behavior of MgB2 in the mixed state is compared with the recent results obtained on Nb3Sn.
Correlations between the structure and superconducting properties of MT-YBaCuO
Authors: Prikhna T A , Moshchill V E , Rabier J , Chaud X , Joulain A , Pan A V , Litskendorf D , Habisreuther T. 
Published: June 2020

Abstract
Comprehensive experimental results of fully oxidized (up to YBa2Cu3O6,9-7) melt-textured YBaCuO materials with different microstructures are presented. These microstructures are built respectively: (1) with a high dislocations density but almost without twins (after high temperature treatment at 2 GPa) and (2) with a high twin density, but practically free from dislocations and stacking faults (after high temperature oxygenation at 10-16 MPa). It is shown that for attaining high critical current densities and fields of irreversibility (jc(H‖c, 0 T)=9·104 A/cm2, H
irr=9.7 T at 77 K), a high twin density in YBa2Cu3O6.9-7 matrix of MT-YBCO is required. The density of twins in fully oxidized materials depends on the distances between Y2BaCuO5 inclusions, larger twin densities are related to shorter distances between inclusions. The influence of phase composition of the initial powder mixtures on the distances between Y2BaCuO5 inclusions have been characterized and discussed.
Frequency-dependent demagnetisation rate of a shielded HTS tape stack
Authors: Tomkow Lukasz , Climente-Alarcon Vicente , Mineev Nikolay , Smara Anis , Glowacki Bartek A. 
Published: June 2020

Abstract
This work presents results of investigation of crossed-field demagnetization in 2G high temperature superconducting stacks at temperatures in the range of 77 - 20 K and in a variable frequency, corresponding to the particular rotor application.
We propose a method to reduce the demagnetization rate for a given stack configuration necessary for the superconducting rotor operating at a cryogenic temperature. This technique involves 3-D wrapping the stack of tapes with perpendicular layers of similar superconducting properties.
Previous ‘proof of concept’ studies documented some improvements in flux demagnetisation reduction for basic configuration. In the present study a more advanced approach based on magnetic flux shielding is adopted. The presented results provide an important contribution to development for design solutions that aim to increase the operational time before remagnetisation of the stacks would be required.
Impact of 440 GeV Proton beams on Superconductors in a Cryogenic Environment
Authors: Will A. , Bernhard A. , Bonura M. , Bordini B. , Mentink M. , Mueller A.-S. , Oslandsbotn A. , Schmidt R. , Schubert J. , Senatore C. , Siemko A. , Verweij A. , Wollmann D. 
Published: June 2020

Abstract
The superconducting magnets used in high energy particle accelerators such as CERN’s LHC can be impacted by the circulating beam in case of specific failures. This leads to interaction of the beam particles with the magnet components, like the superconducting coils, through direct beam impact or via secondary particle showers. The interaction causes energy deposition in the timescale of microseconds and induces large thermal gradients within the superconductors, which are in the order of 100 K/mm. To investigate the effect on the superconductors, an experiment at CERN’s HiRadMat facility was designed and executed, exposing short samples of Nb-Ti and Nb3Sn strands in a cryogenic environment to microsecond 440 GeV proton beams. The irradiated samples were extracted and analyzed for their critical transport current I
c. This paper describes the results and analysis of the measurements of I
c as well as thermo-mechanical simulations of the Nb3Sn strands to evaluate the degradation of I
c as a function of the mechanical strain present during and after the beam impact.
Transport current distribution in soldered joint of BSCCO and REBCO tapes
Authors: Chikumoto Noriko , Yamaguchi Satarou , Shyshkin Oleg 
Published: June 2020

Abstract
Transport current density distribution at the solder joints of BSCCO tapes and GdBCO tapes are examined by means of scanning 3-dimensional (3D) Hall sensor. After measuring the three components,
B
x, B
y
and
B
z
, of self field distribution near the tape induced by the transport current, the current density distribution was calculated by solving the inverse problem through matrix method implemented in the code in MATLAB environment. By using this technique, we successfully obtained the profiles for perpendicular component
J
z
of transport current that is passing through the joint area.
Long term operation of the superconducting triplet quadrupoles with cryocoolers
Authors: Kusaka K 
Published: June 2020

Abstract
Superconducting triplet quadrupoles (STQs) with cryocoolers characterize the BigRIPS in-flight separator and radioactive isotope (RI) beam delivery lines in the RIKEN RIBF (Radioactive Isotope Beam Factory) project. The STQ magnet is a large-aperture superferric quadrupole triplet cooled by liquid helium bath cooling method in a single cryostat. The STQ cryostat is designed to be operated continuously with a Gifford-McMahon (GM)/Joule-Thomson (JT) cryocooler and a GM cryocooler. We operate 22 STQ systems for more than twelve years without warm-up the magnets. We report operational experiences, such as degradation of cooling capacity and failures of compressors, in the long-term operation of the STQ systems. Replacement of ageing cryocooler unit is discussed to improve the cooling capacity.
Mechanical design of a nested 4-layer Canted Cosine Theta (CCT) dipole
Authors: Ortwein Rafal , Blocki Jacek , Kirby Glyn , van Nugteren Jeroen 
Published: June 2020

Abstract
Nested CCT dipoles could be used in particle accelerators and proton therapy machines to bend a beam of charged particles in any direction. In the present study, a mechanical design of a 4 layer nested CCT dipole is evaluated with Finite Element Method (FEM). A full parametric 3D model of a 2.5 Tm 4-layer CCT dipole has been developed using the APDL scripting in the ANSYS software. The, so called, bottom up approach with direct generation of nodes and elements has been utilized, optimizing for the speed of the model generation as the time consuming meshing was bypassed. The properties of the Nb-Ti strands with the surrounding CTD-101K epoxy were obtained with a dedicated homogenization model. Resulting orthotropic properties were fully accounted for in the simulation. The shear stresses in the bonding composite layer: Kapton+S2-glass+CTD-101K were computed. With the results above the limit of 10 MPa, the necessity to provide additional rigidity against the torque was confirmed – castellated design. The shear stresses were mostly caused by thermal effects, and only ~25 % was caused by the Lorentz forces. The influence of the boundary conditions was analysed, leading to their optimal choice limiting the deformation due to Lorentz forces to 91 μm.
Feasibility of ultra-compact HTS CrossConductor based Power Transmission Cables
Authors: Kottonau Dustin , Wolf Michael , Fietz Walter , Stammen Jörg , Hirsch Holger 
Published: June 2020

Abstract
HTS CrossConductor is a compact stacked-tape REBCO conductor of high current density. In this contribution, a non-concentric three-phase cable design based on HTS CroCos is presented, which offers the possibility to reduce the cable diameter significantly. One of the important aspects of HTS-AC power cables are the AC-losses, which are investigated both theoretically and experimentally. For the measurement of the dissipated power loss in both single-phase and three-phase conductor arrangements, a calorimetric method is used. The results indicate that it is possible to reduce the outer cable diameter compared to concentric cables designs by a factor of two. When the losses of such a cable with HTS CroCo design shall not exceed 2 W/m for all three-phases, the maximum ampacity results in a current of 600 A(rms) per phase. Depending of the target there are many potential applications for such an ultra-compact HTS CroCo-based power transmission cable design.
Effect of a PTFE film on bubble triggered DC breakdown characteristics in liquid nitrogen
Authors: Gao Lei , Xiang Bin , Junaid Muhammad , Liu Zhiyuan , Geng Yingsan , Wang Jianhua 
Published: June 2020

Abstract
In the resistive type DC superconducting fault limiter (R-SFCL), the insulation strength will be decreased seriously when the R-SFCL quenched. Insulation barriers are used inside of the R-SFCL to enhance the electrical breakdown strength of the SFCLs. The objective of this paper is to study the barrier effect on the DC breakdown characteristics of the liquid nitrogen (LN2)/insulation barrier composite system with and without bubbles. In the experiment, the DC breakdown voltage of a pair of rod-plane electrodes with an insulation barrier was measured in the presence of thermal bubbles. The results show that for both the positive and negative polarities, the breakdown voltage of the LN2/insulation barrier composite system is higher than that without the barrier. In the presence of the bubbles, the breakdown voltage of the LWinsulation barrier composite system is about 1.5 times higher than without the barrier. Furthermore, the breakdown voltage of the LN2/insulation barrier composite system with 0.04 mm PTFE is higher than with 0.1 mm PTFE. The results suggested that the barrier effect could not only improve the insulation strength of the normal state but also the quench state of the R-SFCLs.
Quench Protection for Superconducting Insertion Magnets
Authors: Green Michael A. 
Published: June 2020

Abstract
Quench protection for Nb-Ni insertion magnets (wigglers and undulators) has not been a problem. The reasons are; the quench is relatively easy to detect, the stored energy is low, the quench propagates rapidly, quench heaters work because the coil thermal diffusivity at 4.5 K is high, and quench protection resistors will work. Superconducting insertion magnets require very high current densities in the magnet coil in order to be competitive with permanent magnet insertion magnets. The need for high coil current densities makes superconductors like Nb3Sn and ReBCO HTS tapes attractive. The higher temperature superconductors have much lower quench propagation velocities, and the high-current-density versions of these materials often have much less copper in them than Nb-Ti. Since the quench temperature for these superconductors is two to ten times higher than Nb-Ti, the coil thermal diffusivity is much lower. This paper presents a number of quench protection options for insertion magnets made from materials other than Nb-Ti.