bluuebunny/crossref_metadata_2025_split huggingface dataset:
Influence of lead-manganese naphthenate on changes in the dynamic edge wetting angle upon spreading of styrene-acrylic dispersion
Authors: Mordasov D , Mordasov M 
Published: May 2020

Abstract
The effect of lead-manganese naphthenate on the change in the dynamic contact angle during spreading of a styrene-acrylic dispersion is studied. The dependences of the change in the dynamic contact angle in time are obtained for various concentrations of lead-manganese naphthenate in solution. As a result of the analysis of the experimental data, a concentration region was revealed in which the dynamic wetting angle varies in the widest range with the lowest speed compared to solutions of other concentrations. The results of the research will be used to optimize the composition of the polymer-mineral composite material and will make it possible to obtain a polymer matrix that most wetts the mineral fillers, and the resulting composite will have the greatest mobility and vitality.
Mathematical model for dynamic characteristics of automatic electrohydraulic drive for technological equipment
Authors: Sokolov V , Krol O , Romanchenko O , Kharlamov Y , Baturin Y 
Published: May 2020

Abstract
The paper is devoted to the development mathematical model of automatic rotary motion electrohydraulic drive for technological equipment and structural scheme of mathematical model for drive as object of automatic control. The hydraulic drive of rotary motion with volume regulation is considered. The drive contains regulated pump and unregulated hydraulic motor. The regulation of the working volume of the pump is carried out by the electrohydraulic amplifier. The transfer function of the regulating process of the pump working volume is represented by aperiodic link of the first order. The adequacy of mathematical model for dynamic characteristics of electrohydraulic drive has been confirmed experimentally by the Fisher criterion. To verify the adequacy, we compared the experimental and calculated transient processes for the shaft angular rotation velocity of hydraulic motor when applying the control signal. The mathematical model of automatic rotary motion electrohydraulic drive for technological equipment as object of automatic control was used as basis for further research on the synthesis of automatic control systems for equipment.
Active technological control of synthesis of high-active catalysts on the surface of solid electrolytes of fuel elements
Authors: Obraztsov D , Chernyshov V , Obraztsova E , Chernyshova T , Dutov M 
Published: May 2020

Abstract
The method of active process control of parameters of synthesized catalysts on electrolytes of solid oxide fuel cells is considered. Using the proposed method, it is possible to obtain a catalyst with a maximum active area. This leads to an increase in the power of the fuel cell. Also, due to carrying out the technological process in strict compliance with the specified optimal parameters, good adhesion of the catalyst to the surface of the solid electrolyte is achieved. It leads to extending of service life of the solid oxide fuel cells. Experimental studies using the proposed method and its measuring control system showed the possibility of obtaining catalysts with minimum deviations from the specified optimal parameters.
Development of solid oxide fuel cells using high-frequency plasma spraying technologies
Authors: Platenkin A , Chernyshov V , Chernyshova T , Dutov M 
Published: May 2020

Abstract
The paper describes the topical issues and the latest achievements in the development of materials with high electrochemical characteristics for single cells and small assemblies of solid oxide fuel cells (SOFC). The authors propose planar SOFC technology which includes sequential deposition of all layers of a thin-film cell on a porous metallic substrate by plasma techniques. The method allows developing porous SOFC anode and cathode, which increases the active area of electrochemical reaction, reduces the spread of technological parameters (in particular, the spread in thickness and porosity of a solid electrolyte), improves SOFC performance and reduces the mass and size of SOFC assemblies. The paper also describes the physics of plasma spraying process in individual cells and SOFC structures. The proposed method is an alternative to traditional SOFC production methods; it eliminates the necessity to use agglomeration technology or other heat treatment. Moreover, it opens up the prospects for automated continuous production process. The appropriate SOFC production equipment is developed, for stationary and mobile use. Further studies will be focused on the task of reducing the weight of SOFC assemblies, which allows using them as an auxiliary power unit for on-board power supply, for example, for cars, airplanes and spaceships.
Simulation of a gas turbine engine rotor assembly
Authors: Bolotov M , Pechenin V , Balyakin D , Pechenina E 
Published: May 2020

Abstract
The quality of aircraft and rocket engines depends primarily on the geometric accuracy of assembly units and parts. Mathematical models implemented in the form of computer models are used to predict quality indicators (in particular, assembly parameters). The work presents a numerical model for predicting assembly parameters of the rotors based on the use of actual surfaces of the parts obtained as a result of measurement on coordinate measuring machines and of mathematical modeling. Aircraft engine turbine rotor parts surfaces are measured on a coordinate measuring machine. Experimental assemblies of three parts were carried out. The measurement error of the parts does not exceed 5 µm, of assembly – 10 µm. Face and radial run-outs were measured for four positions of the disc and retainer in the shaft assembly, with run-outs ranging from 0.08 mm up to 0.1 mm. Calculations of face and radial run-outs of the disc with respect to the base surfaces of the shaft were made using the developed digital model. Relative deviations of the calculated values from the experimental values do not exceed 10%.
Improving student engagement by mathematics learning based on contextual teaching and learning
Authors: Mentari W N , Syarifuddin H 
Published: May 2020

Abstract
Student engagement is important in every learning because learning activities are not just a transfer of knowledge but also as a potential development that is owned by students. This study aims to determine the increase student’s engagement of MTs grade VIII learn based contextual teaching and learning (CTL) learning device in the form of lesson plans and student worksheets. The research design used One Group Design. The sample of this study involved students of class VIII in the 2018/2019 school year were 25 students of class VIII.1 as an experimental class. The instrument used was a student engagement questionnaire and field notes. Data were analyzed quantitatively using means and n-gain and described descriptively. The results showed that the n-gain was 0.215, which means that there was an increase in the student’s engagement learning by using CTL-based mathematics learning in the low category.
Application of Fuzzy Time Series-Markov Chain Method in Forecasting Data of Exchange Rate Riyal-Rupiah
Authors: Permana D , Fitri I A 
Published: May 2020

Abstract
Currency rates are one of the important indicators in the context of an economics country. The value of a country’s currency always increases and decreases in value against another country’s currency at any time. In this research, we make a model of dynamical currency rates data among Riyals and Rupiah. The data are obtained from the official website of Bank Indonesia. The aim research is to predict the currency rate between Riyal to Rupiah in the future time with the Markov Chain Fuzzy-Time Series method. The results of this research are data processing in the form of error value of the forecast used AFER and MEA methods. Those are 0.827% and Rp32.96 rupiahs respectively. The forecast value for the next 10 days are Rp3,779; p3,774; Rp.3,774; Rp3,779; Rp3,764; Rp3,760; Rp3,763; Rp3,797; Rp3,777 and Rp3,784.
Effectiveness of Mathematics Learning Tools Based on Guided Inquiry Model to Mathematical Communication Capabilities of Class VIII Students
Authors: Kurani R , Syarifuddin H 
Published: May 2020

Abstract
This study discussed on the effectiveness of the use of mathematical learning tools based on guided inquiry models to improve mathematical communication skills (CS) for students of grade VIII SMP. The type of development research used is the Plomp model. The study was conducted on 30 students in one class to use learning tools, then given a final test to see how many students completed the test. The results showed that 86.6% had completely exceeded the minimum completeness criteria that had been set at 70. It could be concluded that the learning tools developed in the form of RPP and SW were effective in improving students’ mathematical communication abilities so that they were suitable for use. Start your abstract here…
Needs Analysis to Develop Mathematics Teaching Material of Senior High School (SMA) Based on Problem Based Learning
Authors: Jannah M , Yerizon Y , Musdi E 
Published: May 2020

Abstract
Students’ ability in solving mathematical problem has optimal yet. This is due to mathematics learning provide less opportunity for the students to get involved in a challenging problem during learning process. The purpose of this research is to develop learning devices in the form of lesson plan and worksheet based on Problem Based Learning (PBL). This is a development research. The development model employed in this research is Plomp Model. This model consists of 3 phases, namely, preliminary research, development or prototyping phase, and assessment phase. In this part, the reported one is the preliminary research. The result of data analysis on preliminary research shows that: 1) Teacher is not able yet to develop learning device in order to improve students’ ability in problem solving. 2) Students’ inability to solve story problem. 3) Students are not capable to work on different question from the sample given. 4) Students are expecting to have a real life context problem on worksheet in relation with their daily life. 5) Students prefer to work on group. 6) Students who live in a rural coastal area tend to be less motivated and less active in the learning process.
The Development of Learning Devices with Realistics Mathematics Education Based in Program of Mechanical Engineering and Automotive Engineering
Authors: Huda A , Armiati A 
Published: May 2020

Abstract
The aim of this research is to develop the math learning devices with RME-based in mechanical engineering and automotive engineering programs for students of grade 10. The devices designed are adjusted to the students’ major. The students of mechanical engineering learn about design, construction and operation of machinery, while automotive engineering students focus on the design and construction of cars. Learning devices were designed in the form of lesson plans and students’ worksheets. The development model used in this research was Plomp model. This paper focuses on the preliminary research. The preliminary research covers needs analysis, curriculum analysis, concept analysis and students analysis. The instruments used were questionnaire sheets, interview sheets, and observations. Data analysis technique is a qualitative data analysis technique. The result of the preliminary research shows the learning devices made by the teachers were universal for all major and ignore the character of each major, neither mechanical engineering nor automotive engineering. The curriculum analysis done toward the syllabus and KD of math and the productive subjects related. The result of this preliminary research will be a guidance in prototype of learning devices that will plan.
Factors affecting students’ capabilities in analyzing by using flow proof in real analysis lectures
Authors: Helma H , Murni D 
Published: May 2020

Abstract
Real analysis is required for mathematicians. The competency is that students are able to analyze and think critically in solving a problem, and write their solutions in a logical statement. Students must have the definitions and theorems to solve the problems and perform a process which is often called the preliminary analysis. After that, students construct the proof based on the preliminary analysis. Based on the characteristics of the problem in real analysis, the solution given to the problem is using flow proof in composing preliminary analysis. Before the learning materials are prepared, it is important to know the characteristics of learners in following the learning of mathematics that affect the learning outcomes. There are five factors that influence the learning outcomes, namely background, interest, attitude, motivation and learning styles. The purpose of research is to determine the factors that influence learning outcomes. This research is a descriptive. The instruments are assessment sheets for students’ characteristics and test. Results are the factors that influence the learning outcomes of students directly are background and learning style.
Analysis of students’ mathematical communication skill in calculus course
Authors: Rusyda N A , Ahmad D , Rusdinal R , Dwina F 
Published: May 2020

Abstract
The purpose of this research is to analyse the mathematical communication skill of student by using essay test. The method of this research is a quantitative approach with descriptive. We assess the communication skill from the students who take calculus course. The results showed the percentage of achievement of mathematical communication skill indicators of students were: 1) 45.7% students can express mathematical ideas in oral or written form into images, algebraic expressions, and graphics; 2) 34.3% students can state mathematics problem in daily life into a symbol or model in mathematics; and 3) 51.4% students can interpret figures into mathematical ideas. Based on the percentage, the mathematical communication skills of students in calculus course is still low and need to be improved for further research.
Source of Self-Efficacy for First-Year College Students Based on Gender and Prior Knowledge
Authors: Yenti I N , Kusumah Y S 
Published: May 2020

Abstract
Self-efficacy has important role in determining the success and adjustment of first-year college students, including college students in study programs of mathematics education. The purpose of this study is to analyze the source of self-efficacy of first-year college students based on gender and prior knowledge. The research method used is descriptive. The study sample consisted of 68 students enrolled in calculus lectures and 58 students enrolled in algebra lectures. Other researchers have tested instrument of self-efficacy for there students. This study finds that a source of self-efficacy of first-year college students, namely vicarious experience and mastery experience affects more male and female students. Vicarious experience is the most dominant source of self-efficacy for each category of prior knowledge.
Development of mathematics learning devices based on realistic mathematics education for financial accounting expertise program in vocational high school (preliminary research)
Authors: Sutiaharni S , Armiati A 
Published: May 2020

Abstract
Financial Accounting is one of expertise programs in Indonesia Vocational High Schools. The prospective Vocational High School graduates are expected to be equipped with a great problem-solving skill which demanded in the field of working. Mathematics is the lesson that develop students’ problem-solving skill. This paper discussed development in learning devices based on realistic mathematics education for financial accounting expertise program in Xth grade Vocational High School. The research was conducted until preliminary research phase by using Plomp model. Based on the interview results conducted on Mathematics teachers in SMK N 2 Padang and SMK N 3 Padang, the writer concludes that the mathhematis learning devices commonly used by teachers are general without giving differences in the characteristics of each expertise program, specifically in financial accounting programs. Lastly, students have low mathematics problem-solving skill.
Pre-service teachers’ perception on science, technology, engineering, and mathematics (stem) education
Authors: Rifandi R , Rahmi Y L , Widya  , Indrawati E S 
Published: May 2020

Abstract
STEM education has become a trending topic to be discussed among educational experts. However, there is still limited data about preservice teachers’ perception about it. Therefore, the aim of this study is to describe teachers’ perception about Science, Technology, Engineering and Mathematics (STEM) education. This study is a descriptive research using survey method. The data were collected through questionnaire. The collected data was analyzed by using percentage technique. The result shows that there is positive perception among the preservice teachers about STEM education and they are agree of implementing it to educational curriculum in Indonesia.
An initial observation of learning devices and mathematical problem solving ability of senior high school students
Authors: Fitriani N , Arnawa I M 
Published: May 2020

Abstract
A good learning devices will deliver students to have good mathematical problem solving skills. This type of research was a descriptive research by qualitative approach. The initial observation was aimed at finding out, reviewing and explaining problem-solving ability of high school students in mathematics learning and condition of learning devices used and developed by teachers, then whether it was necessary to continue research development based on realistic mathematics education to improve the mathematical problem solving ability. The results of observations at SMAN 14 Padang and SMAN 15 Padang, can be concluded that the learning devices used do not link to real life problem that the instructional becomes meaningless. Learning devices used were still general and have not been able to facilitate the students to find their own concepts and did not help the students to improve problem solving ability. An approach that can accommodate it is a realistic mathematics education. The result needed to follow-up in form of research on development of realistic mathematics education based learning devices to improve the mathematical problem solving ability of senior high school students.
Development of learning devices based on problem based learning to improve the problem solving ability at grade VII of SMP
Authors: Ridwan M A , Armiati  
Published: May 2020

Abstract
The aims of this research was to produce the learning devices based ona valid Problembased learning (PBL) to improve the students’ problemsolving ability They are lesson plan and students’ worksheet. for grade VII SMP. PBL aims to involve students in solving problems using real-world problems as a context for students to learn through problem solving ability. Learning devices using a PLOMP Model consist of three stages: the preliminary investigation phase, the development phase and the evaluation phase. Learning devices are said to be valid if they meet the validity of content and construction. The result of research known that instrument used is a validation sheet containing the presentation aspects, content worthiness and material, graphic and language. Expert validation results show that learning devices meet valid criteria.
Development of learning tools based on contextual teaching and learning in fifth grade of primary schools
Authors: Yuwandra R , Arnawa I M 
Published: May 2020

Abstract
The goals of this study is to produce the learning tools of mathematics with a valid, practical and effective CTL approach. The developed learning tool consist of a lesson plan and a student worksheet. The development model used in this study is the Plomp model (preliminary research, prototyping phase, and assessment phase). The device created is used to improve understanding of concepts and mathematical problem solving for elementary school students. The instruments used were validation sheets, teacher, and student response questionnaires and mathematics learning achievement tests. Learning devices are said to be valid if they meet the content and construct validity. Practicality seen from the ease of use of the device. The effectiveness of the device seen from the percentage of students’ completeness of the test at least 70%. The results of the experts’ validation show that the learning device meets the valid criteria. Practicality reaches very practical criteria based on the questionnaire responses of teachers and students. The percentage of students’ completeness tests is 75%.
Learning Trajectory for Teaching Division using RME Approach at Elementary Schools
Authors: Fauzan A , Yerizon Y , Yolanda R N 
Published: May 2020

AbstractThe research aimed to develop learning trajectory (LT) to teach the topic of integer division based on Realistic Mathematics Education (RME) which is valid, practical and effective through research on the development of Gravemeijer & Cobb types. The trial subjects were the third-grade of elementary school students in Padang. The research was supported by data collection techniques in the form of document analysis, observation, interviews, questionnaires, and tests. Data analysis was performed using descriptive statistics and parametric statistics. The results showed that the LT developed to teach the topic of integer division using RME helped the teacher in learning. LT describes the characteristics of RME and facilitates students in a class. Besides, LT can help students to find integer division algorithms. Students are more confident in using their strategies for solving the contextual problems so that students’ mathematical problem-solving abilities also develop.
Gaps in science and policy formulation of climate change: perspective from university
Authors: Mardiastuti A 
Published: May 2020

Abstract

Abstract. In relation to climate change, policy formulation based on science is needed to determine further strategic actions. Unfortunately, there have been several gaps that hampered the implementation. This paper explores these gaps from a stand point of university, one of strategic partner of the government as the policy maker and regulator of climate change. The identified major gaps are: (1) no specific courses dealing with climate change, although research centers have been established; (2) insufficient number of lecturers who specialized in climate change; (3) research in climate change are long-term that requires big funding, except for carbon estimation; and (4) need to use sophisticated math modelling that requires specific skills. Climate change science is extremely complex, encompass various knowledge disciplines, developed very fast, and covering a global scale. Besides as strategic pools of expert, university lecturers also have important roles to educate students who might involve in future research and policy formulation. Therefore, these gaps need to be addressed, to produce effective policies formulation and then translating them into action programs. In addition, Indonesia needs to have a likelihood science group in climate change who will provide a regular scientific assessment to be translated into policy by the government.