bluuebunny/crossref_metadata_2025 huggingface dataset:
The effect of comic-based realistic mathematics approach on students’ learning motivation and conceptual understanding
Authors: Sipayung T N , Simanjuntak S D , Wijaya A , Sugiman S
Published: June 2020

Comics are reading material that is generally more desirable than textbooks by children, especially teenagers. Based on its characteristics, comics contain stories in the form of pictures and text which is contained in the balloons of text and presented in the panels. If the comic is presented in line with the application of a realistic mathematical approach, especially in learning mathematics, it hopes to create an interesting learning atmosphere for students. However, in this case, the contents of the comic story presented are in the form of learning about integers that are connected with a realistic mathematical approach. Therefore, this study aims to determine the effect of learning with comic-based realistic mathematical approaches on learning motivation and students’ understanding of mathematical concepts. This research is a quasi-experimental study. The population in this study was all the students of class VII of Junior High School of RK Serdang Murni Lubuk Pakam in the Academic Year of 2019/2020. While the sample was the class VII-1 as a control class of 31 students and class VII-2 as an experimental class of 32 students. The instruments in this study were two tests of the ability to understand the mathematical concepts and a learning motivation questionnaire. The normality test uses Liliefors test and the homogeneity test uses the Levene’s test with significance. The data were analyzed using the Manova test. Based on the data analysis, the results show that there was a significant effect of comic-based realistic mathematical approaches on students’ learning motivation and conceptual understanding of integer’s material.
Submicron-sized MoRe-doped Si-MoRe Josephson junctions with a low specific capacitance
Authors: Kalenyuk A , Shapovalov A , Shnyrkov V , Shaternik V , Belogolovskii M , Febvre P , Schmidl F , Seidel P
Published: June 2020

We start with a short look at the problem of low-capacitance Josephson junctions, its history, and actual state-of-the-art. It is argued that such devices are important for applications requiring nonhysteretic current-voltage characteristics since reduction of capacitance by several times makes it possible to increase the device resistance by the same amount while keeping the McCumber-Stewart damping parameter unaltered. Moreover, at very high frequencies the capacitance in the RCSJ circuit with a parallel connection starts to shunt the superconducting current component due to reduction of the corresponding reactance inversely proportional to C. Hence, to extend the operating frequency range of a Josephson junction its capacitance should be as small as possible. As a solution of a new type of the Josephson device, less resistive and with smaller capacitance, we propose and realize a submicron-sized trilayer with tens nm-thick Si interlayer doped by metallic ultra-small inclusions and superconducting Mo-Re alloy electrodes.
A superconducting flux-flow oscillator of terahertz range
Authors: Kinev N V , Rudakov K I , Filippenko L V , Fominskiy M Yu , Baryshev A M , Koshelets V P
Published: June 2020

We have elaborated, fabricated and tested a THz source radiating to open space based on the superconducting flux-flow oscillator (FFO). In this concept, the oscillator is integrated with the transmitting lens antenna based on a slot structure in Nb film with a thickness of ~200 nm located on the same chip. The slot planar antenna is matched to the oscillator (by input) and to the semielliptical Si lens with a diameter of 10 mm (by output) providing a narrow output beam of THz emission. A harmonic mixer based on the superconductor-insulator-superconductor junction embedded in the “FFO and antenna” integrated structure has been used for the phase locking of the oscillator. Several designs of antenna coupled with the oscillator by microstrip lines have been numerically simulated, and the batches of experimental samples based on Nb-AlN-NbN superconducting trilayers with Rn
·A ~ 20 Ω·μm2 (jc
~ 10 kA/cm2) have been fabricated and tested. Two different setups were used for experimental study: a THz spectrometer based on the SIS receiver with a high spectral resolution (better than 0.1 MHz) and a Si bolometer. The overall operating range of 250 to 700 GHz is covered by all the developed designs.
Modeling the Resonance Shifts Due to Coupling Between HTS Coils in NMR Probes
Authors: Thomas J N , Ramaswamy V , Johnston T L , Belc D C , Freytag N , Hornak L A , Edison A S , Brey W W
Published: June 2020

Nuclear magnetic resonance (NMR) probes using thin-film HTS coils offer high sensitivity and are particularly suitable for small-sample applications. Typically, HTS probes are optimized for the detection of multiple nuclei and require several coils to be located within a small volume near the sample. Coupling between the coils shifts coil resonances and complicates coil trimming when tuning HTS probes. We have modeled the magnetic coupling between the coils of a 1.5-mm all-HTS NMR probe with 13C, 1H, and 2H channels. By measuring the magnetic coupling coefficients between individual coils, we solve the general coupling matrix given by KVL for six coupled resonators. Our results indicate that required trims can be accurately predicted by applying single coil trimming simulations to this magnetic coupling model. Use of the magnetic coupling model significantly improves the efficiency of tuning HTS probes.
Comparison of the Effect of Graphene and Graphene Oxide Doping on YBCO
Authors: Gaffoor M Z , Jarvis A L L , Young E A , Dorrell D
Published: June 2020

Weak-links in high temperature superconductors (HTS) are a result of an incorrect stoichiometric ratio found in grain boundaries and misaligned planes. These weak-links severely decrease the critical transport current of the bulk HTS material (such as YBCO) and increase resistance in the normal state. Bulk YBCO was doped with graphene oxide (GO) and reduced graphene oxide (rGO) in the following dopant concentrations: 0, 0.1, 0.5, 0.7, 0.9 and 1 % wt. Through mechanical hardness testing, it was observed that the hardness of the samples increased as the GO and rGO concentration increased. The 1 % wt. doped GO and rGO samples was observed to be hardest, with a true hardness of 2.630 GPa and 2.405 GPa respectively, compared to the control sample with a true hardness of 1.499 GPa. Critical transition temperature (TC
) of the GO doped YBCO samples are greater than rGO doped samples and is presumably related to the higher oxygen content found in GO. The 0.7 % wt. doping for GO and rGO samples had the highest critical transition temperature of 98 K and 91 K, respectively. Both GO and rGO samples showed a decrease in normal resistance up to 0.7 % wt. doping, compared to the control sample. The weak-link effect was most improved in the 0.7 % wt. doped samples for GO and rGO.
Improvement of trapped magnetic field in GdBCO by waveform control pulse magnetization at 70 K
Authors: Ida Tetsuya , Watanabe Shunya , Watasaki Masahiro , Izumi Mitsuru
Published: June 2020

We attempted to trap a strong magnetic field with a single pulsed magnetic field by applying waveform control pulse magnetization (WCPM) method to a high-temperature superconductor (HTS) bulk sandwiched between two vortex-type copper coils at less than 77 K. The GM cryocooler conductively cooled the GdBCO bulk to 70 K in an arrangement similar to the internal structure of our axial gap type HTS motor. The HTS bulk showed no flux jump, while the duty ratio of WCPM was small. When we increased the duty ratio, we found a flux jump without looking at any prior signs and the trapped magnetic flux density increased twice. Hence we attempted a negative feedback WCPM with the control target at the highest trapped magnetic flux density while no flux jump was found. After trial and error of control conditions, the HTS bulk sample trapped a maximum magnetic flux density of 1.79 T by a single pulse magnetic field. If the WCPM technique is used, a single pulse magnetic field will cause the HTS bulk to obtain a higher trapped field at lower temperatures.
Modifying the critical current anisotropy of YBCO films via buffering layers on IBAD-MgO based templates
Authors: Khan M. Z. , Rivasto E. , Wu Y. , Zhao Y. , Chen C. , Zhu J. , Palonen H. , Tikkanen J. , Huhtinen H. , Paturi P.
Published: June 2020

The role of variations in the buffer layer structure of IBAD-MgO based templates on the critical current anisotropy has been investigated in undoped and BaZrO3 (BZO) doped YBa2Cu3O6+x
(YBCO) films. Not only do the natural defects grow distinct within the undoped YBCO lattice but also due to the different lengths of BZO induced nanorods within the YBCO matrix, the flux pinning properties are greatly affected by the underlying layers which in turn has a great impact on the angular dependent critical current density J
c(θ). This has been verified by transport measurements where the shape of the J
c (θ) varies in accordance with the substrates. Based on our results, the template having a cap layer with the minimum lattice mismatch and a good chemical compatibility with deposited YBCO is proven to be the best for growing both the undoped and BZO doped YBCO films. Furthermore, a model we can present based on the shapes of J
c(θ) curves depicts how the formation of nanosized defects affects the flux pinning anisotropy.
Superconducting properties and surface roughness of thin Nb samples fabricated for SRF applications
Authors: Ries R , Seiler E , Gömöry F , Medvids A , Pira C , Malyshev O B
Published: June 2020

Using a thin Nb layer on Copper substrate has several advantages compared with the bulk Nb in construction of Superconducting Radiofrequency accelerating cavities (SRF) for particle accelerators. We were evaluating the properties of two series of Nb layers deposited on Cu substrate, mainly by determining the start of magnetic flux penetration into the sample – the first magnetic flux entry field B
en, proportional to the B
c1. The values of B
en are compared with the surface roughness and surface morphology of the Nb layers, which have a strong influence on B
en. The surfaces of the samples were also treated by Nd:YAG laser depending on laser irradiation dose. The results of B
en and surface roughness before and after laser polishing are compared.
Effect of non-uniform proton irradiation on the critical current of REBCO tapes
Authors: Yamamoto H , Ito S , Miwa M , Matsuyama S , Hashizume H
Published: June 2020

Generally, uniformly-distributed irradiation defects such as artificial pinning centers improve the critical current, I
c, of REBCO tapes in strong external field. On the other hand, at self-field or low field, irradiation is not effective for improving I
c. However, if non-uniform pinning center distribution similar to vortex profile is assumed, this would increase I
c at selffield. Therefore, in this study, we experimentally investigated the effect of partial irradiation on I
c based on the assumption. We prepared REBCO tapes irradiated with trihydrogen cations in the c-axis direction. Three different patterns of defects were examined; overall, edge-only and center-only irradiations. We measured I
c at 77 K, 25 K and 15 K using the four terminal method. Results showed that, while I
c was not improved after the irradiations for each pattern, I
c behaviour depends on the patterns; edge-only-irradiated tapes showed the highest I
c and overall irradiation caused the largest I
c degradation at 77 K. However, center-only-irradiated tapes showed the lowest critical current at 25 K and 15 K which may be due to enhancement of flux pinning effect at lower temperature. Moreover, pinning centers in the edge region might be more effective to increase I
c, though further investigation on the effect of non-uniform pinning centers is required.
Influence of local deformation on critical current of high temperature superconductor tape
Authors: Kujovič Tomáš , Gömöry Fedor
Published: June 2020

In many applications, high temperature superconductor (HTS) tapes are placed on top of uneven surfaces. Because the electrical properties of HTS tapes are sensitive to mechanical loading, mechanical stress generated at such local imperfections can considerably decrease the critical current of a HTS tape. Then a method of predicting degradation of critical current from a numerical simulation would be helpful.

We present the results of 3D mechanical finite element model analysis, using the software ANSYS for optimising the geometry of a round CORT (Conductor-On-Round-Tube) cable. In these simulations, the HTS tape is bent around a circular former of certain diameter with a surface imperfection. We used three parameters to characterize the imperfection geometry: diameter of the former, the height and the width of imperfection. In order to validate the mechanical simulation results, we performed in-situ measurement of critical current of HTS tape.
Superconducting Properties of a Prototype Pancake Coil using a MgB2 Rutherford-type Stranded Conductor
Authors: Onji T , Ishihara A , Kobayashi Y , Tomita M , Hira M , Yagai T , Takao T , Makida Y , Shintomi T , Hirano N , Komagome T , Tsukada K , Hamajima T
Published: June 2020

Our group has developed a coil using MgB2 wires for SMES. In this paper, a prototype coil using a MgB2 Rutherford-type stranded conductor was fabricated based on react-and-wind (R&W) method. In the R&W method, a Rutherford-type conductor in which nine MgB2 wires were wound at pitch of 450 mm around a copper former were manufactured using reacted wires (performed by Columbus Superconductors SpA), and then coiling was performed. The coil was cooled by conduction cooling and the I-V properties were evaluated under magnetic field. As a result, in the R&W method, critical current of a coil was degraded, since making a coil by hand would cause the strain beyond the scope of the assumption which was the marginally allowable bending strain. This result suggests the coil for SMES proposed in ASPCS is difficult to react before twisting, and Rutherford-type conductors should be fabricated before reacting, which means that coil processing should be performed based on the React after making stranded conductors and Wind method, or the wind-and-react method.
Geometrical surface pinning in the nonlinear AC susceptibility of HTS tapes
Authors: Smith A P , Raine M J , Surrey E , Hampshire D P
Published: June 2020

The analytic expression for the nonlinear magnetic susceptibility of a thin disk derived from Bean’s model with a uniform J
C for

B
∥

n
^

predicts a peak-peak ratio of 7.1 (5.4) for the real (imaginary) components of the third harmonic χ
3 susceptibility. Our measurements show a peak-peak ratio closer to 1.1 in the real component and a noise limited lower estimate of ≈ 7 in the imaginary component. The anomalous third harmonic can be explained by the presence of a geometrical surface barrier for flux entry and exit which we have included as a small region of enhanced current density, J
C,G, close to the surface of the disk. The geometrical surface current density is predicted to be approximately equal to J
C,G ≈ 2B
C1/μ
0
d. In 2G HTS tapes with d ≈ 1μm and B
C1 ≈ 5mT this is J
C,G ≈ 8GAm−2. We have measured both J
C,B and J
C,G using the nonlinear susceptibility of a Superpower tape without artificial pinning in fields orthogonal to the tape up to 35T. We find a geometrical surface current of J
C,G ≈ 10GAm−2 and an average critical current density J
C which is in good agreement with transport measurements performed on material from the same reel of tape.
Feasibility Study of a Novel Superconducting DC Induction Heater Structure
Authors: Yan X F , Dai S T , Zhang J , Xu Y
Published: June 2020

A novel superconducting DC induction heater which can heat more than two aluminum billets at a time is proposed. The workpiece can rotate on its axis and move around the center cylinder of the iron core. In order to evaluate the effect of the movement speed and the rotation speed on the heating the aluminum billet, a 2D simulation model has been built by the finite element software. And the magnetic flux density distribution and the temperature distribution under different movement speed for different rotation speed has also been evaluated. Results show that the movement can improve the temperature uniformity of the aluminum billet at the cost of increasing the heating time. What is more, the new superconducting DC induction heating structure is feasible.
Dielectric strength of insulating material in LN2 with thermally induced bubbles
Authors: Gromoll D , Schumacher R , Humpert C
Published: June 2020

To realize a reliable and cost-effective application of high-temperature superconductive (HTS) equipment at high-voltage (HV) levels, the influence of thermally induced gas bubbles on the dielectric strength of different solid insulating materials in liquid nitrogen (LN2) was investigated. A heatable copper tape electrode arrangement was developed simulating HTS tapes with insulation in between. AC breakdown measurements were performed without and with forced boiling on insulating papers, polypropylene laminated paper (PPLP) and polyimide (PI) films. Under nucleate boiling the influence of bubbles on the dielectric strength of all materials was not significant. However under film boiling the dielectric strength of the insulating papers decreased to a level comparable to their dielectric strength in air, demonstrating the insufficient impregnation of porous materials under film boiling. For PI there was no degradation at all. PPLP retained about 70% of its basic dielectric strength in LN2.
Simulation of the Thermal Performance of HTS Coated Conductors for HVDC SFCL
Authors: de Sousa W T B , Kudymow A , Strauss S , Palasz S , Elschner S , Noe M
Published: June 2020

Within the EU-funded project FastGrid a resistive superconducting fault current limiter for DC-application is actually under development. To reduce substantially the amount of deployed superconducting tape an increase of voltage per length in the limitation case is needed. Moreover, the resistive transition (quench) should be fast and uniform. In the present work, the thermal behavior of three different architectures of coated conductors are investigated by means of transient simulations. The first architecture is composed by an additional Hastelloy shunt layer, which is supposed to avoid overheating of the conductor during fault limitation. The other architectures include layers of silver and copper as stabilizers. Our parameter study including the geometries of the different layers and the inhomogeneity of the critical current density of the superconducting tape shall lead to an optimized tape layout. First comparisons with experiment indicate, that, with the first architecture, electric field strength up to 100 V/m should be within reach.
Current limiting characteristics of a magnetic shielding type Superconducting Fault Current Limiter of REBCO pancake coils
Authors: Sakamoto D , Sakamoto T , Shirai Y
Published: June 2020

Superconducting Fault Current Limiters (SFCLs) are installed in the electric power system, and expected to limit fault current and improve system stability. In this paper, we focus on the transformer magnetic shielding type SFCL made of REBCO wires. This SFCL limits fault current mainly with reactance for small fault current. When fault current gets larger, resistance component is added and a larger impedance is generated. In this time, we fabricated the transformer type SFCL composed of pancake coils and investigated the basic characteristics. The pancake coil type has the advantage that the amount of superconducting wire is less and the size of SFCL becomes smaller than solenoid coil type. As the results of experiment, it was confirmed that SFCL limits fault current with reactance and resistance properly. Regarding the current limiting impedance, it almost agreed with the designed value, and confirmed the current limiting operation as expected.
Experimental study on cabling properties of different REBCO coated tapes
Authors: Xiao G Y , Liu F , Jin H , Zhou C , Qin J G , Liu H J , Li J G , Dai T L , Zhang X T
Published: June 2020

Due to the high current carrying capability, the ReBCO coated tapes are good candidates for magnets operation under a high magnetic field and high current conditions. Cabling the ReBCO conductor tapes on round core (CORC) is one of main cabling concepts. It has the potential to be used for future fusion magnets. However, during the cabling process, the ReBCO tape shall be subjected to strain and stress caused by the combined tension, bending and torsion. It is well known that strain and stress shall reduce the current carrying properties of ReBCO tapes, especially if it is under conditions of normal strain and/or peeling stress. The critical current never returns to its original value once the stress and strain exceed a critical value. Therefore activities were carried out to wound ReBCO tapes with different dimensions on a round core with different diameters. All of the used tapes are from Shanghai Superconductor. The critical current variation of the tape at 77 K and self-field with its thickness, width as well as the used diameter of the round core have been investigated to give guidance for the followed cable design and manufacturing.
Test results of a REBCO superconducting switch for reducing temporal fluctuations in driven-mode
Authors: Iwai S , Otani Y , Miyazaki H , Tosaka T , Nomura S , Ito T
Published: June 2020

High-temperature superconducting magnets are generally driven by a power supply (driven mode), and temporal fluctuations of the power supply unit, such as ripple noise, directly affect the magnetic field stability. A method of suppressing such temporal instability by short-circuiting both ends of the coil with finite low-resistance joints, somewhat similar to a persistent current switch, has been proposed in order to form a closed loop having a large time constant, L/R. In this research, we developed two types of REBCO superconducting switches was constructed with a non-inductive winding using mainly ordinary copper-coated REBCO tapes, and type-B switch used uncoated REBCO tapes toward application to emergency shutdown. For the type-B switch, at the end of the winding, copper-coated REBCO tapes were jointed to prevent degradation by exposure to moisture. The R-T and V-I characteristics of each switch when cooled with liquid nitrogen were tested. The type-A switch was applied to a test REBCO magnet, and the temporal stability of the magnetic field was evaluated under a conduction cooling configuration in the driven mode.
Using of HTS tape coils for the design of a magnetic bearing
Authors: Kurbatova E , Kurbatov P , Kuschenko E , Kulaev Y
Published: June 2020

The use of HTS materials for the construction of magnetic bearings has shown their high efficiency. Currently, more and more research is focused on the use of tape superconductors for magnetic bearings. Application of HTS tapes allows simplifying the manufacturing technology of these devices and improving the specific power characteristics. However, when modelling devices with HTS tapes, computational difficulties arise due to the small thickness of the active layer. The paper considers the possibility of using models for magnetization to describe the properties of HTS tapes in the calculation method based on the integral equations of an electromagnetic field. The features of the proposed models are illustrated by the results of solving simple test tasks and calculations of real designs of magnetic bearings. To confirm the correctness of the simulation, the calculation data are compared with the data of experimental studies.
High Temperature Superconducting (HTS) Cable Application to Ship Deperming Work
Authors: Hirota M
Published: June 2020

We study a system of high electric current cable laid on the seabed for purpose of naval ship magnetic deperming. Moderate magnetic field over 2400 A/m is to be imposed on the volume equivalent of several thousand tons of ship, with alternately changing direction and gradually decreasing intensity. Cable with conventional conductor needs large power source because of the requirements coming from the cable’s resistivity and high decay of magnetic field depending on distance from source. High Temperature Superconducting cable is suitable for this application. We set a requirement of maximum current of the cable as 200 kA and the length as 1200 m set on seabed of 12 m depth. Our recent design of the cable composed of Rare-earth-Barium-Copper-Oxide tape conductor stack, bundled and cooled by helium gas to 50 K. As a next step, cooling to 20 K with the same base concept of cable is shown to mitigate high expense of the tape conductor.
High Temperature Superconducting Halbach Array Topology for Air-cored Electrical Machines
Authors: Zhang Hongye , Li Quan , Ubani Okechukwu , Mueller Markus
Published: June 2020

Air-cored electrical machines have attracted increasing attention in applications related to aircraft and wind power because they can eliminate core losses and decrease the total mass. However, the limited magnetic flux in air-cored machines has restricted their power level. In order to improve the power density and efficiency while further reducing the weight of air-cored electrical machines, a novel field winding topology composed of high temperature superconducting (HTS) Halbach Array magnets (HAM) has been proposed in this paper. C-GEN is an innovative multi-stage air-cored generator technology with permanent magnets, which has been demonstrated at laboratory scale. Taking a 1 MW C-GEN generator prototype as the example machine, anH-formulation founded HTSHAM model has been built in COMSOL Multiphysics with the homogenization method. Simulation results show that the proposed HTSHAM C-GEN generator can achieve a power density more than 4 times higher than the conventional design with permanent magnets (PM), with a reduced magnet weight of around half of the previous prototype. The proposed HTSHAM represents a generic approach for the design of fully air-cored superconducting synchronous machines, eliminating heavy ferromagnetic material, and thus provides a useful reference for the design of low-weight air-cored electrical machines with a high power density.
T - formulation based numerical modelling of dynamic loss with a DC background field
Authors: Kails K , Yao M , Zhang H , Machura P , Mueller M , Li Q
Published: June 2020

High-temperature superconducting (HTS) generators offer the advantages of high efficiencies and increased power densities. Most superconducting generator designs feature DC field windings to provide the required magnetomotive force. The superconducting field windings in HTS machines are subject to complex magnetic fields, which lead to dynamic losses occurring in the winding. This magnetic field environment has a large DC background component due to the self-field of the superconducting field windings. This paper investigates the dynamic loss in combination with a DC background field using a T – formulation based numerical model, where the dynamic region is used to identify the dynamic loss. Our double claw pole generator design, which offers a high power density at low superconducting tape requirements, is used as a case study for dynamic loss analysis with a DC background field. Results show that DC background field has a strong effect on the dynamic loss due to the reduced critical current. In addition it was shown that the T – formulation based numerical model in conjunction with the dynamic region requires further research to accurately predict the dynamic loss due to the changing DC current transport region.
The utilization of corncob for the manufacture of charcoal briquette as an alternative fuel
Authors: Rahmawati S , Pathuddin  , Sakung J , Suherman  , Fudholi A , Sushmita L
Published: June 2020

Biomass of sweet corncob and birdlime that is much found in society is the garbage that until now have not widely used as a product that have value added. This research aims to use biomass of sweet corncob and the birdlime as an alternative fuel to substitute fossil energy sources. One alternative to make sweet corncob and birdlime as an alternative fuel is process them into charcoal briquettes so it can produces high calorific value. The process to make charcoal briquettes from corncob and birdlime is very easy which includes charcoal raw material drying, preparation of the adhesive, printing and drying the Briquettes. Besides, the testing of briquettes quality of sweet corncob includes: density (0.54 – 0.78 gr/cm3), calorific value (4936.454 cal/gr), water level (6.39%), ash level (3.8%), vaporized substance level (16.72%) and bonded carbon level (79.48%. Whereas, birdlime corncob include: density (0.61 – 1.3 gr /cm3), calorific value (6033.650 cal/gr), water level (6.83%), ash level (4.8%), vaporized substance level (18.41%) and bonded carbon level (76,48%).
Student profile multiple representations skills under the implementation of OBSIM (observation and simulation) model of teaching in improving creative thinking skills
Authors: Ridlo Z R , Sutarto  , Mahardika I K , Indrawati  , Terra I W A , Wardani E
Published: June 2020

The research aims to explore multiple representations under the implementation of the OBSIM model of teaching in the alternating-current circuit course. This research compares the modern class (experimental class) and traditional class with the traditional teaching style. Experiment class applies the OBSIM model of teaching, and Traditional Classroom teaches in traditional style with a direct explanation. Computer simulation also integrated into this research by using Matlab Sofware as part of multiple representations, namely programming representation. This research used triangulation methods. The quantitative methods were applied to analyze student achievement tests according to Creative thinking criteria. The Qualitative method was applied using observation of student activity. Student achievement test followed by a pretest, and post-test quasi-experimental research. The data analysis form pretest and postest analysis indicates a significant value of 0.012 (p ≤ 0.05). Thus, it is a significant value, and the average of student activity in experimental class better than control class. The findings conclude that two classes have differences in terms of student multiple representations and creative thinking skills after implementation of OBSIM model of teaching.
An analysis of olympiad students’ critical thinking in solving National Science Olympiad (OSN) problem on number theory material
Authors: Jatmiko D D H , Fatahillah A , Oktavianingtyas E , Rochmah O A
Published: June 2020

This research aimed at describing the process of the mathematical Olympiad students in solving National Science Olympiad (OSN) problem on number theory material. The subjects of the research were 4 Olympiad students at Pythagoras Development Center of Mathematics and Natural Sciences Jember. The data collection methods used were test and interview. In this case, every student had strengths and weaknesses in solving the problem. All of the students were able to write and explain what was known and asked but they were still lack to model the problem into mathematical form. The students were able to formulate properly but were lack to construct it into various possible answers. All of the students were able to write systematic steps and correct conclusion. All of the students checked all the results, but there were still some students who were not careful in checking, so there were inappropriate answers.
STEM education for pre-service teacher: why and how?
Authors: Nasrudin D , Rochman C , Suhendi HY , Helsy I , Rasyid A , Aripin I , Utami W , Mayasri A
Published: June 2020

The success of STEM implementation in primary and secondary schools is greatly influenced by the role and expertise of the teacher. In the Indonesian context, not many universities have STEM centers yet. This paper wants to describe the STEM education design for pre-service science teachers at Universities. The method used was a Focus Group Discussion from several researchers with backgrounds in physics, chemistry, and biology across universities. The results of the study show the importance of developing STEM education programs in certain subjects, applying STEM learning to pedagogical practices, open courses that specifically train, develop STEM teaching for pre-service teachers and build the STEM center. This study concludes the importance of an integrated program between preparing STEM education at universities and implementing STEM in the field.
The colloid labyrinth media to improve students motivation and learning achievement on chemistry lessons
Authors: Erna M , Susilawati  , Haryati S , Alodia F
Published: June 2020

The colloid labyrinth media is a game media that can be used in learning chemistry topics taught in high school. The type of this research was experiment research with design randomized control group pretest-posttest design. This research object is students of SMA 8 Pekanbaru. The sample of this research consisted of 32 students of XI IPA 9 as the experiment group and 35 students of XI IPA 10 as the control group at the 2016/2017 academic year which were determined randomly after conducting normality and homogeneity test. The experiment class was treated with the use of labyrinth media while the control class without the use of labyrinth media. The data analysis was using the analysis of descriptive statistic and t-test. Based on analysis of the data obtained tcount > ttable is 2.63 > 1.67, it’s mean that the use of labyrinth media can improve students learning outcomes on the subject of colloid in XI IPA SMA Negeri 8 Pekanbaru. Based on the data analysis, it is obtained students motivation in experiment groups (66.14%) than control group (40.95%), means that the use of labyrinth media can improve students motivation on the subject of colloid in XI IPA SMA Negeri 8 Pekanbaru. The category improvement of students learning achievement at experiment group was high category with N-gain normalized is 0.8633.
Science textbook based on Socio-Scientific Issues (SSI) for environmental pollution to increase student science literacy in junior high school
Authors: Anggraini S D , Indrawati  , Wahyuni D
Published: June 2020

21st century learning leads to problem solving, social emotional skills to face the challenges of RI 4.0 and it will have an influence scientific understanding. This scientific understanding is still low in analyzing and applying the concept of a problem that has an impact on the ability of science literacy. Science literacy is related ability to think scientifically by using knowledge and identifying natural phenomena. The results of the distribution of questionnaires for 18 junior high schools in Jember middle region of 89% stated the concept of science literacy of students was still lacking. Science literacy has a close relationship with Socio-Scientific Issues (SSI) which are described as social problems with a scientific context that connects students with scientific issues that are developing in society to be explored such as environmental pollution problems. This research used quasi-pretest-posttest experiment without control class. Data analysis using the mixed-method, and were analyzed quantitatively.The sample used was 33 students junior high school in VII C class room. The result obtained from pretest and posttest with open questions following aspect of science literacy and showed that students experienced an increase in science literacy by 0,75 in the high categories.
The application of Lesson Study for LearningCommunity (LSLC)- based collaborative learning - integrated Realistic Mathematics Education (RME) to improve the students’ mathematical reasoning ability class IX D of MTSN 5 Jember on quadratic equation material
Authors: Kusumawati R
Published: June 2020

Students in each level of education are required to have mathematical reasoning ability. Students’ mathematical reasoning abilities were very low. Therefore, this research investigated the application of lesson study for learning community-based collaborative learning-integrated realistic mathematics education to improve the students’ mathematical reasoning ability. The method used was classroom action research and the material was quadratic equation in class IXD of MTsN 5 Jember in odd semester in 2019/2020 academic year. Mathematical reasoning was assessed through essay test. The data were obtained from the results of learning achievement test, conducting the observation, interview and observation of activity results of the teacher and students during the learning through lesson study for learning community-based collaborative learning-integrated realistic mathematics education. The mean result of pre-test on the students’ mathematical reasoning ability was around 42.50. While the mean result of post-test on the students’ mathematical reasoning ability improved as much as 88.13. This means that in the cycle I, the students’ mathematical reasoning improved. This indicated that lesson study for learning community-based collaborative learning-integrated realistic mathematics education improved the students’ mathematical reasoning ability.
Adiwiyata School: An environmental care program as an effort to develop Indonesian students’ ecological literacy
Authors: Febriani R , Farihah U , Nasution N E A
Published: June 2020

In line with the increase of complexity in environmental problems as a result of over-exploitation, it is necessary to care for the environmental program. Ecological literacy education needs to be realized in the programs of environmental care. This study aims to determine the importance of Adiwiyata school program in an effort to improve students’ ecological literacy. The method used in this research is qualitative descriptive with interview, observation and documentation as data collection techniques. Ecological literacy is a collective action which needs togetherness to produce a positive impact to the environment. The application of ecological literacy at schools requires awareness from all teachers, students and other school community. Adiwiyata program in SMAN 5 Jember, Indonesia can increase students’ ecological literacy by establishing a caring attitude and environment on students. This is evidenced by the behaviour of students who dispose of waste in place, sort out the types of garbage, recycling of waste, making hydroponics plants are free of pesticides, and composting. It can be concluded that inveronmental care program (Adiwiyata) is one way to improve the literacy of students in the school about ecology by observing the effectiveness of Adiwiyata program.
Factors behind the implementation of STEM education in Bangladesh
Authors: Chowdhury S A , Arefin ASM S , Ahmed F
Published: June 2020

In this world of ever growing challenges; Science, Technology, Engineering, and Mathematics (STEM) has gained momentum in global education systems. Unfortunately, Bangladesh as a country is yet to be on board with this advanced education system. No research has been published related to STEM education in Bangladesh. Hence, the aim of this study was to explore the key factors and major challenges behind the implementation of STEM education system in Bangladesh. The design of the study followed mixed method approach. Undergraduate students of the University of Dhaka were selected as sample using non-random purposive sampling technique. Data were collected from the participants through semi-structured questionnaire and focus group discussion. According to the primary findings, more than 80% of the respondents agreed that infrastructure and resources as well as professional development are the key factors to implement STEM in Bangladesh. In addition, inadequate scientific laboratory facilities, lack of financial resources, lack of training for trainers and large class size have been identified as the major challenges behind the implementation of STEM. Keeping these factors and challenges in mind, an effective STEM based education system can be developed and successfully implemented in phase by phase from primary to tertiary levels. This study has, therefore, implications for policy makers, educationists and stakeholders in both private and public sectors to increase the country’s global competitiveness as well as boost the national economy via providing the STEM based skills and capacity to the learners.
The analysis of dyscalculia that referred to the learning style of fleming and mills theory on matrix materials of MAN 1 Metro students
Authors: Jannah T M , Bharata H
Published: June 2020

This study aims to: (1) Investigate the learning problems from students, (2) To know the learning styles of students, (3) To identifies the dyscalculia experienced by students on matrix based on their learning styles of Flaming and Mills Theory. The subject of research are students of MIA 6 MAN 1 Metro grade XI, in the 2018-19 Academic Year. The research uses descriptive qualitative method. The results of this research are: (1) the students of class XI MIA 6 had four difficulties of learning mathematics such as (a) spatial disruption: not describing the steps of operating on the answers done, (b) the difficulty of understanding the concept: not making the problem answer correctly, (c) the difficulty of understanding the formulas or symbols: the incomplete of writing formulas the use of false step and the use of wrong formulas and symbols, and (d) the difficulty in calculation: the lack of students accuracy during the operation of the work; (2) students of class XI MIA 6 have four styles (VARK) they are Visual (V): 8 students, Audiotori (A): 13 students, Read-Write (R): 7 students, and Kinesthetic (K): 8 Students, and found students who have combined learning styles of Audiotori and Read-Write (AR): 2 students, Audiotori, Read-Write and Kinestetik (ARK): 1 student, and Visual, Audiotori, Read-Write and Kinestetik (VARK): 1 student; (3) The difficulties of learning mathematics experienced by students are also attributed to their V-A-R-K learning style; Visual students (V): spatial disruption and difficulty of understanding formulas or symbols. Audiotori Students (A): spatial disruption, the difficulty of understanding concepts, and calculations. Read-Write student (R): spatial disruption and the difficulty of understanding formulas or symbols. And Kinesthetic students (K): spatial disruption, the difficulty of understanding concepts, formulas or symbols and calculations.
The effect of self efficacy on students’ motivation and learning outcome of class 8 in build flat side space material
Authors: Farihah U , Rakasiwi P
Published: June 2020

The purpose of this study was to determine the effect of self efficacy on student’s motivation and learning outcomes in the topic of build flat side space. This study was conducted at class 8 of SMP Negeri 12 Jember east Java, Indonesia in the 2019-2020 academic year. This research used a quantitative approach in the type of survey research. Simple random sampling was used as the sampling technique. Data collection technique used were questionnaires and tests. Simple linear regression test was used to analyse the data. The research finding showed that there is an influence of self efficacy on student learning motivation (sig 0.000) but there is no influence on student learning outcomes (sig 0.062). The influence of self efficacy on learning motivation is 49.7%, while 50.3% is influenced by other factors not discussed in this study
The implementation of lesson study as a tool to improve the students’ higher order thinking skill on trigonometric material regarding creative thinking skill
Authors: Hadianto N , Hobri  , Irvan M
Published: June 2020

The development of lesson study-based learning tool where students are able to involve directly in the learning so it is expected to improve their creative thinking skill. This research aimed at developing lesson study-based learning tool to help the students improve their creative thinking skill at SMK Darussalam in Trigonometry material validly, practically and effectively. This research used Plomp development model research design consisting of 3 phases covering: (i) Preliminary Research, (ii) Prototyping Phase and (iii) Assessment Phase. This research was the learning tool development research and experimental research by using Quasi Experimental Design method and Non-equivalent Post-test Only Control Group Design. In this research, the sampling technique used was simple random sampling. Out of 7 population classes, 2 sample classes were selected namely class X TKJ 1 as the experimental class which was given the treatment by using teaching material development and class X TKJ 2 as the control class by using direct learning. The data analysis technique used descriptive analysis to test the validity, practicality and effectivity as well as through mix method analysis to analyze the results of the students' learning achievement between the experimental and control classes. The results of this research revealed that: in the pre-test phase, from the experimental class, there were 3 students who belonged to L4 level, 1 student from the control class and in the post-test phase, from the experimental class, there were 8 students who were at L4 and only 1 student from the control class. With a significance of [t=1.15 and df = 61, p>0.05] in the pre-test phase and the value of [t=4.04 and df = 61, p<0.05] in the post-test phase and in the regression test, the values of tcount was 4.649 and ttable in degrees of freedom (df) = N − 2 = 33 − 2 = 31 with a significance of 95% as much as 1.196 with a determination of tcount > ttable (8.296 > 1.196) therefore Ho was accepted and Ha was rejected with a provision that there was a significant influence of lesson study method on the students' creative thinking skill.
Research on Application of Double Fuzzy Algorithm in Voltage Filtering of Aluminum Electrolysis Cell
Authors: Deng Lianwen , Jiang Haibin , Zhao Yan , Liu Guotao
Published: June 2020

At present, the electrolytic aluminum control system uses a first-order algorithm to filter the voltage of the electrolytic cell with serious hysteresis and weak tracking. Aiming at the above problems, this paper researches and designs an adaptive filter based on double fuzzy algorithm. The change of the electrolytic cell voltage measured, the absolute value of the difference between electrolytic cell measurement voltage and filtered electrolytic cell voltage are used as the two input variables of the fuzzy controller 1. The change of the electrolytic cell voltage measured,the absolute value of the difference between electrolytic cell measured voltage and corrected electrolytic cell voltage are used as the two input variables of the fuzzy controller 2. The two fuzzy controllers calculate the filter coefficient and the correction coefficient respectively through a fuzzy algorithm. Simulation results show that the tracking time of the double fuzzy algorithm is 78% shorter than that of the first-order algorithm, and the root mean square error is reduced by 70% compared to the first-order algorithm. It can provide a feasible and excellent filtering algorithm for the intelligent control of electrolytic aluminum.
Intrusion Detection through Contiguous System Call Traces
Authors: Chen Lin
Published: June 2020

The server backend operating system for the Servers and scientific computing necessities is a big market, and the majority market share of this market is hold by the Linux based Operating System for a very long time period. However, as running in backend lack of humanity monitoring, and the default signature-based security measures are ineffectual for detecting stealth attacks, the Linux OS needs an intelligent intrusion detection solution. This paper proposed an automatous method to inspect the contiguous system call traces and identify the abnormal system call pattern only by analyzing a trace of small window size, rather than probing the full traces.