bluuebunny/crossref_metadata_2025 huggingface dataset:
A profile of vocational high school students’ adversity quotient towards mathematics
Authors: Wardani Y , Mahmudi A
Published: November 2019

This study aims to discover the adversity quotient of Vocational High School students towards mathematics, which is divided into three categories namely climber (high), camper (average) and quitter (low). Adversity quotient is influenced by four dimensions including control, ownership, reach and endurance. This survey study had 132 respondents taken from the tenth grade of Vocational High School students, specifically from four departments (office administration, accounting, multimedia, and management). There were 60 items in the questionnaire used to collect the data about the students’ adversity quotient. The questionnaire was arranged using Likert scale which had reliability score of 0.92. The result showed that 27% of students were in climber category, 72% of students were in the camper category and 1% of students were in the quitter category. Based on the percentages, adversity quotient of Vocational High School students towards mathematics is quite good, but improvement is necessarry because learning mathematics requires higher adversity quotient.
Technology-enhanced mathematics learning: A perspective from Cognitive Load Theory
Authors: Chen Ouhao , Woolcott Geoff
Published: November 2019

Cognitive load theory is an instructional theory used to guide the design of effective instruction. The cognitive architecture that underpins cognitive load theory can be described by five principles, essential components that form the basis of many well-tested and well-known cognitive load effects. One of these documented effects, the worked example effect, indicates that showing novices worked solutions rather than asking them to generate solutions could facilitate learning by reducing levels of cognitive load. This paper will demonstrate how the worked example effect can be used in designing interactive podcasts to improve mathematics skills.
Content Analysis of Higher Order Thinking Skills (HOTS) in Mathematics National Exam
Authors: Ratna A M , Retnawati H
Published: November 2019

Higher Order Thinking Skills (HOTS) is a hot topic in education world. It is important for students because they can learn some skills of HOTS to solve their real life problems. However, some previous researches show that there were only a few samples of HOTS questions found in national exam. Knowing that national exam is one of assesment standard in national scale, the researchers are going to analyse the content of HOTS in national exam kit, especially on the last three years of senior high school mathematics exam: 2017, 2016, 2015. This is a qualitative research. The steps taken to analyse are as follows: 1) unitizing (distinguish units according to the characteristic of HOTS), 2) recording (collect data based on the instruments and give additional description about the data) 3) reduction (reduce irrelevant things about HOTS) 4) inferring (present the percentage of HOTS content and make a conclusion of the result). The result revealed that there were only 3.33%, 2.5%, 4.17% of HOTS content in mathematics national exam in the year of 2015, 2016, and 2017, resepectively. The distribution of each category of HOTS content was less evenly distributed.
The Reluctance of Students to Ask in Mathematics Learning: How Does The Teacher Solve It?
Authors: Nuri Bulan , Marsigit
Published: November 2019

This study aims to describe factors that cause passivity and are reluctant to ask students during learning, as well as to see what efforts made by the teacher to overcome the problem. So that later it will give an illustration of the extent to which the teacher understands and knows the impact of the learning that has been done. Participants from this study were 12 mathematics teachers who had 10-34 years of teaching experience. The Result show that the majority of teachers thought that fear and shame were the main factors for causing students’s low participation and reluctant to ask. Unfortunately, there are still many teachers who have not realized that the learning method used. In addition, the effort made to overcome these problems is to provide motivation and make an interesting and comfortable learning atmosphere. That is the answer which is most expressed by the teacher.
Students’ Ability Of Mathematical Problem-Solving Based On SOLO Taxonomy
Authors: Saputra D C , Nurjanah A , Retnawati H
Published: November 2019

One of the critical purposes of learning mathematics is to improve the problem-solving ability. To figure out the level of students’ ability in mathematical problem-solving, this study employed SOLO taxonomy. 32 students of VIII grade in SMP Muhammadiyah Bantul were involved. Their level of mathematical problem-solving ability was categorized based on SOLO taxonomy that consists of pre-structural, uni-structural, multi-structural, relational, and extended abstract. Using a qualitative descriptive method, data were collected by problem-solving test in a pattern of number material and interviews. The results revealed that most students are in the uni-structural level, both of upper and lower group students. This finding shows that the students need to be supported and well facilitated in order to reach higher levels, such as relational and extended abstract levels.
Variations of the problem-solving strategies in plane geometry of junior high school students
Authors: Pratikno H , Sugiman
Published: November 2019

The purpose of this study was to explore the problem-solving strategies of junior high school students on plane geometry topics. Using a qualitative approach, as many as 40 students were given tests and one student was interviewed on each of the different problem-solving strategies. After checking the results of student answers, it turned out there were three strategies used by students. The first strategy was that students are able to answer questions by guessing the answer directly then testing them. The second strategy was that students use ratio in finding answers. The third strategy was that students used analogy strategies with variables. The results showed that 13 students used the first strategy, 20 students used the second strategy, one student used the third strategy, and six students did not use the strategy or did not answer. The most used problem-solving strategy by students is the ratio strategy, with the percentage of students using the strategy is 50% of the total students who participated in this study.
Utilizing mobile phones in mathematics class: teachers’ and preservice teachers’ perceptions
Authors: Nofriyanti Devi , Setyaningrum Wahyu
Published: November 2019

Mobile phones are one of the technologies that can be used to support mathematics learning, but currently the use of it in the classroom seems to be rarely used by teachers in Indonesia. This study examined a total of 44 mathematics teachers and 62 mathematics preservice teachers’ perception in Indonesia for the use of mobile phones in the classroom. Participants were given a questionnaire to determine their support for mobile phones use. The results showed that majority of the participants supported the use of mobile phones for learning. They agreed that mobile phones are useful to provide learning opportunities anywhere and anytime, increase access to technology in the classroom, and provide opportunities for differentiation in instruction. As for barriers, participants worry about students’ access application that is not in accordance with the teacher’s instructions. They perceived that instructions, control of students and time allocation are the things that teacher need to pay attention before using this media. Although majority teachers reported their support for the use of mobile phone in the classroom, the implementation of this media needs to be improved.
Improving trigonometry learning motivation using Geogebra-Assisted Guided Discovery Student Worksheet (GDSW)
Authors: Hernawati Kuswari , Surjono Herman Dwi
Published: November 2019

This study aims to determine student motivation using Geogebra assisted GDSW. The instrument of this research are worksheet compiled with guided discovery approach and student motivation questionnaire. The motivation questionnaire consists of three aspects of interest, pleasure, and satisfaction, which are outlined in 15 questions submitted to 118 of 10th grade students. Data analysis of the questionnaire using Likert scale 1-4, with ideal score is 4, and the lowest score is 1. There are five interval classes. The result of this research, that student motivation using Geogebra assisted GDSW has an average of 3.11 with the category of "good". It means that students have good motivation on learning using Geogebra-assisted GDSW.
A survey on the perception of students against technology in learning mathematics
Authors: Fitriasari L , Abadi A M
Published: November 2019

Discoveries related to information and communication technologies change the viewpoints of humans against the world including the world of education. The role of technology supports many activities, especially learning activities, and it also can support the learning process. Education systems in the globalization era show the transformation which is previously manual and conventional into the system that effectively and efficiently can improve the information technology. Thus, this research aims to identify the perception of students toward technology in learning especially mathematics. This study uses a survey approach, with data collection methods namely questionnaires distributed to 42 students. The results show that 70% of students had enthusiasm and interest in technology especially mathematics learning.
Self-regulated learning in blended learning approach
Authors: Setyaningrum W
Published: November 2019

Blended learning allowed students to manage their own pace of learning especially in the online session. This might foster students’ self-regulated learning. This claim, however, need to be investigated with more empirical data. This study, therefore, intended to examine the effect of blended learning on students’ self-regulated learning. A quasi-experiment with the pretest and posttest group design was employed in this study. A total of 115 grade 10 students was cluster randomly selected among senior high schools in the city of Yogyakarta. Two different classes of samples were set, namely experiment class using blended learning android-based-game, and control class using offline class. The students in the two classes learn the same material that is about Function and its graph. Data of students’ self-regulated learning was collected through a questionnaire with five Likert scale. The data was analyzed using Analysis of Variance (ANOVA) technique and it was found that: there is a significant difference of self-regulated learning between students who learn in blended class and those in offline class. This study offers insights on the use of blended learning to foster the students’ self-regulated learning especially in learning mathematics. Nevertheless, the design of blended learning need to considered particularly when and what kind of learning material should be delivered online and offline.
Learning mathematics from erroneous example in individual and collaborative setting: is it effective to facilitate students’ mathematical disposition?
Authors: Rafi I , Setyaningrum W
Published: November 2019

Learning mathematics from an erroneous example—worked example contains error—in individual and collaborative setting could be potential to facilitate students’ mathematical disposition through activities such as find, explain, and correct the errors as well as solve a problem similar to the erroneous example. This study was intended to examine the effectiveness of learning mathematics from the erroneous example in individual and collaborative setting with regards to students’ mathematical disposition. This quasi-experimental research with non-equivalent group pre-test and post-test design employed a 30 items-questionnaire to gather data of mathematical disposition. The participants were 45 students of grade 11th in the one of public senior high school in Yogyakarta. The collected data of students’ mathematical disposition then were examined by using paired samples t-test, one sample t-test, and one-proportion z-test. This study revealed that learning mathematics from erroneous example could not significantly facilitate students’ mathematical disposition in both individual and collaborative setting. The possible reasons behind these findings are discussed.
Is there any interaction effects of students’ gender and mathematical disposition towards learning achievement?
Authors: Andari I E , Sugiman
Published: November 2019

Mathematics learning achievement is affected by external and internal factors. External factors include the environment and teachers, while one of the internal factors is the student’s gender. However, the research findings of gender difference effects on learning achievement showed varied results. It indicates that there might be other factors which have important effects on gender differences towards learning achievement, such as mathematical disposition. The aim of this quantitative study is to describe the interaction effects between students’ gender and mathematical disposition towards learning achievement. Participants consisted of 200 high school students. Data were obtained using a questionnaire on a Likert scale and the score of the daily test result. Furthermore, the data were analysed using Two-way ANOVA. Findings revealed that there is no interaction effect between the two variables towards learning achievement. As an individually separated factor, mathematical disposition does have an effect on students’ learning achievement, but, is not the case with students’ gender. Results and recommendations are further discussed in this paper.
Students’ perception of tutoring judging from students’ academic ability
Authors: Nugroho I A , Jailani
Published: November 2019

This study aims to find out the perception of students with high academic abilities and students with academic skills that are not high on the implementation of tutoring by tutoring institutions in schools. This type of research is qualitative research with descriptive analysis. The sample in the study were students of Junior High School. Data collection instruments use interview and documentation guidelines. The results of this study are 1) Students’ perceptions based on the expectations of the learning guide regarding academic ability have been fulfilled, there is no significant difference in perception concerning students’ academic abilities. Learning precision tends to increase. 2) Students’ perceptions are reviewed based on the need for tutoring regarding students’ academic abilities, in general, have also been fulfilled, meaning students with various academic skills feel they need tutoring to be able to support the learning process.
Analysis of student difficulties on algebra problem solving in junior high school
Authors: Sugiarti L , Retnawati H
Published: November 2019

Algebra is one of the mathematical sciences studied in junior high school. Some students may have difficulty learning algebra. This study aims to determine the difficulties experienced by students in solving the problem of algebraic operations. The type of this research is qualitative research with case study approach. Subjects in this study are students of grade 8D 1 Salam Magelang junior high scchool, Central Java in the semester of the year 2016/2017 academic year. Methods of data collection used include algebraic operations tests, open questionnaires, and documentation. Data analysis techniques through data reduction, data presentation, and conclusions. The result of the research that there are students’ difficulties in doing algebraic problems related to concept and principle. Students difficulties experienced related to the concept of difficulty in determining variables and constants including but not understanding the definitions of variables and constants, and difficulties in applying the concept of division in algebra. The difficulty experienced in terms of principle is the application of the principle of addition to the algebraic form, the reduction in algebraic form, multiplication on the algebraic form, simplifying algebraic fractions, factoring, and solving algebra-related stories.
Profile of students’ mathematics anxiety
Authors: Azizah L N , Mahmudi A , Retnawati H
Published: November 2019

Mathematics anxiety has gained massive attention from researchers and mathematics teachers. It happens among students and even becomes a determinant of their view towards mathematics in the future. This study purposes to observe the profile of students’ mathematics anxiety in one of public junior high school in Sleman, Yogyakarta, Indonesia. The type of this research is descriptive quantitative research. This study engaged a purposive sampling technique, and the instrument used is a sheet of mathematics anxiety questionnaire with Likert scale. The analysis conducted is descriptive. The result of the analysis indicates that students’ mathematics anxiety profile tends to belong in the medium category. Based on the results of research and discussion, it can be concluded that the students’ mathematics anxiety in one of public junior high school in Sleman needs to be well-managed.
Analysis of junior high school national examination year 2014 to 2017 on facilitating students’ high order thinking skill
Authors: Rozien M I , Retnawati H
Published: November 2019

One of the thinking skills of students who are being talked about by various groups in the general public and education is higher order thinking skills (HOTS). In Bloom’s taxonomy, HOTS is a student’s ability to answer questions with a level of analyzing, evaluating, and creating. One form of test that is presented by the implementation standard of assessment in Indonesia is the National Examination. Regarding this matter, the analysis of HOTS content on the national examination tool is an urgent matter to do. This study aims to determine the contents of HOTS in the National Examination of Junior High School Mathematics subjects in 2014 to 2017. This research is a descriptive study with a qualitative approach. Data was collected with non-tests given to several experts. Sources of data obtained by researchers came from their own researchers, 2 mathematics teachers, and 3 mathematics lecturers. In the validity of the data and decision making, it is obtained from the quantity of opinions from the six experts. The results showed that the HOTS items from 2014 to 2017 were different. The number of HOTS items in the National Examination from 2014 to 2017 were 12, 16, 18 and 10. However, from the HOTS items in 2014 to 2017 there were no questions about type C6, namely creating.
The effect of changes in mathematics curriculum in improving students’ reasoning skills and mathematical problem solving
Authors: Yaman N A P , Jailani
Published: November 2019

This study aims to describe the effect of changes in mathematics curriculum on mathematical reasoning skills and problem solving for junior high school students in Bima, Indonesia. Curriculum changes in Indonesia are motivated by several factors, including because students still have not been able to maximize the power of reasoning and problem solving so that the previous applied mathematics curriculum is deemed necessary to be refined so that the power of reasoning and solving mathematical problems can be maximized by students. The data in this study were obtained through giving a test to the eighth grade junior high school students in Bima. The evidence of validity of instruments was obtained from an expert judgment in the form of agreement on the feasibility of the each item of instruments. The estimation of reliability of instruments using the Kuder-Richadson formula (KR-20) with the reliability coefficient for reasoning and problem solving instruments are respectively 0.72 and 0.73. The results showed that there were no significant differences in mean scores of mathematical reasoning and problem solving between students of The Previous Mathematics Curriculum group and students of The New Mathematics Curriculum group indicated by the F 0.02 value with a significance value of (p) 0.162 in the two test group MANOVA or there is no effect of changes in mathematics curriculum on students’ reasoning abilities and mathematical problem solving. This study also found that students from both groups obtained the lowest average score on reasoning indicators drawing conclusions, while the lowest average score of the two groups of students in solving mathematical problems was on the aspect of understanding problem information.
Numerical characterisation of the performance of flow rate on a non-contact vortex gripper
Authors: Anand Chandran C S , Sajikumar K S , Jayaraj K
Published: November 2019

On manufacturing industries like semiconductor wafers, Manufacturing of medicine or Food processing industries require repeated handling of clean products such as wafers, Food products, etc. which are needs to be frequently handled and transported. This handling can be further ameliorated by Vortex Grippers. Vortex levitation can achieve Non-Contact handling by blowing air through a tangential nozzle into a vortex cup, thus swirling air flow forms which generates negative pressure. The suction force generated by the vortex is more than enough to keep the workpiece without contact. In the present study, a non-contact handling device called vortex gripper is modified by changing some design parameters. However, when a conical shaped vortex cup is used, a 60% increase in gripper lifting force is achieved with the same air consumption as reported early.
Fluid structure interaction simulations and experimental validation of a pipeline immersed in liquid
Authors: Kumaresan D , Lekshmi A , Srinivas Kodati , Thomas Suresh Mathew , Sruthy S
Published: November 2019

In launch vehicles, there are number of fluid systems to cater to various requirements like propellant filling, draining to/from tanks, venting of ullage gases, pressurization of the tanks, feed systems to convey propellants to engine from tanks, lines to convey command gas to actuate various valves etc. These pipe lines are subjected to environmental loads i.e. vibration loads when the launch vehicle starts its course to place the satellite into its designated orbit. It is essential to study the dynamic characteristics of these pipe lines for the design of them for vibration loads. The response of these pipelines depends on fluid environment in which they are immersed. If a pipe line is immersed in liquid, its dynamic characteristics vary largely from that of a pipeline vibrating in ambient environment (air). If the pipe line immersed in fluid, natural frequency reduces and damping increases due to the added mass and fluid viscosity respectively. In order to study these effects, FSI studies are carried out on a pipe line immersed in water using ANSYS CFD and Mechanical software. Convergence studies with respect to time scale are carried out to benchmark the simulation procedure. This simulation procedure is validated by conducting the experiments.
Numerical Analysis of Combustion and Film Cooling in LOx-Methane Rocket Engine
Authors: Arun M , Amith Raj R , Jose Prakash M
Published: November 2019

Nowadays methane is considered as an alternative fuel for rocket engine application. It is abundant in the outer solar system that can be harvested from mars, Titan, Jupiter, many other planets and moon. The properties of cryogenic methane like higher density, higher vaporization temperature, less challenge in storage requirement compared to cryogenic hydrogen and its higher specific impulse, superior cooling capability and higher coking limit compared to kerosene created a renewed interest on space scientist in choosing methane as a propellant. Combustion and film cooling involving supercritical and transcritical regimes in a high pressure rocket engine combustion chamber is a challenging problem for the rocket engine designers. At supercritical and transcritical conditions, the thermophysical and transport properties exhibit tremendous variations which makes modeling combustion and cooling a demanding task. The present study is based on the oxygen methane thrust chamber model B at DLR P6.1 test bench. The finite volume based software ANSYS Fluent 15.0 is used for the numerical studies. The combustion is simulated using single step eddy dissipation approach. The real gas effects are incorporated using Soave Redlich Kwong cubic equation of state. The numerical scheme is validated by comparing the results obtained with the experimental results reported in literature. Investigations have been carried out to study the effect of film cooling on chamber wall temperature and wall heat flux for different oxidizer inlet temperature. The result revel that the hot gas temperature near the wall is higher in the transcritical combustion compared to supercritical combustion.
Enhancement of the thermal performance of a loop heat pipe using silica-water nanofluid
Authors: Jose Jobin , Baby Rajesh
Published: November 2019

Loop heat pipes (LHPs) are heat transfer devices which are capable of transferring large amount of heat energy over long distances. This paper presents the results of numerical investigations carried out to determine the effect of silica-water nanofluid on the thermal performance of a LHP. Silica-water nanofluid at 2 % nanoparticle concentration and deionised water are considered as working fluids. The power input is varied from 40 to 320 W in steps of 40 W. The numerical results are validated with experimental data available in the literature. LHP using deionsed water is used as the baseline case. The results shows that silica-water nanofluid can significantly enhance the thermal performance of the LHP when compared with the baseline case. The evaporator temperature of LHP using nanofluid reduced by 27 % than the baseline case. The LHP attained steady state faster (150 s earlier) with the presence of silica nanoparticles due to enhanced thermal properties. Thus silica-water nanofluid based loop heat pipes proves its potential as a suitable working fluid for a wide range of applications.
Thermodynamic modelling of hybrid adsorption system
Authors: Abhishek P , Baiju V
Published: November 2019

The ability of adsorption based desalination system to cogenerate distilled fresh water and cooling effect provides an increasing attention in the field of cooling and desalination technologies. Eco-friendly adsorption cycles are capable of producing the hybrid effects (desalination& cooling) with low temperature heat source having temperature range from 50°C to 90°C. Adsorption characteristics (isotherm) of silica gel-water and zeolite-water have been presented in this study. Dubinin-Astakov (D-A) and Dubinin-Radushkevich (D-R) adsorption equilibrium equations are used for comparing the performance of silica gel and zeolite. Results show that maximum water production rate in the case of silica gel adsorbent is stabilised at lower regeneration temperature, ranges from 80°C to 120°C, where as in zeolite it is in the higher range from 150°C to 250°C. Maximum COP of the system obtained is 0.65 for silica gel-water at a regeneration temperature of 80°C where as 0.35 for zeolite-water at 110°C. Study concluded that the performance of the system using silica gel-water adsorbent is comparatively better than zeolite-water pair.
Study of Modified Fuel and Advanced Zeolite-Copper Oxide Nanocomposite Catalytic Converter in a Diesel Generator
Authors: George Kurian , Azeem B A Mohamed , Raju Rijin , Surendran Sujith , Divakaran Neethu , Fazil A
Published: November 2019

The issue of environmental pollution from diesel engines is a cause of major concern, even though diesel engines provide high thermal efficiency. This problem can be reduced to an extent through the use of modified fuel and catalytic converters. This study focus on improving the energy density of fuel by blending it with metal particles and hence increasing the thermal efficiency and ignition within the combustion chamber. Diesel was blended with nano and micron aluminium particles separately using ultrasonicator. Sorbitan monooleate was used as the surfactant. The catalytic converter was developed by making modification inside the silencer by placing stacks of mesh, which were coated with zeolite copper oxide nanocomposite. The nanocomposite matrix was prepared using copper nitrate solution and zeolite powder in an alcoholic medium, treated with a reducing agent. Engine performance test was carried out separately for both nano and micron aluminium blended diesel in a single cylinder four stroke, air cooled, direct injection Kirloskar engine. The experiment was carried out by varying the load at a constant speed of 1500 rpm to evaluate the performance characteristics. Emissions from the diesel generator fuelled by diesel and modified fuels were recorded by OPAX gas analyser both in the presence and absence of catalytic converter. The results indicated an increase in brake thermal efficiency by 8% and 72% for micro Al blended diesel and nano Al blended diesel respectively, in comparison with ordinary diesel. The emission test using catalytic converter gave 50%, 34% and 17% decrease in CO emission for ordinary diesel, micro-Al blended diesel and nano Al blended diesel respectively.
Optimizing the exhaust emission from logistics and packing industries, by means of green logistics
Authors: Benrajesh P , Rajan A John
Published: November 2019

The product packing, is an essential process for preserving the product but it also emits higher percentages of green house gases to the atmosphere, while decomposing it. Therefore, it leads to a new science named ‘Green packing’, which deals with the process of identifying Eco-compatible materials for packing. This article aims at detecting: the high performing packing factor for green house gas emission and also to develop an optimized values for packing enterprises to mitigate the emission. The results achieved shows that packing material selection has a huge influence on green house gas emission.
Methodology for preparing a Cost-Value Stream Map
Authors: Rajesh Menon B , Shalij P R , Kiron K R , Sajith V S , Sreejith J
Published: November 2019

This paper proposes the methodology for preparing the Cost Value Stream Map (CVSM) which possesses the advantage of measuring the cost involved and time consumed in the production process stream. A value stream map addresses the value addition process in terms of time domain in a production process. CVSM addresses both the time and cost information simultaneously in a production process. This CVSM method equips the study of the production process in detail and helps to figure out the wastages in the process directly in terms of the cost involved in the production. The cost line added alongside the time line in the modified VSM is a simple tool which can be utilised by lean experts in identifying the wastage in production process in terms of the cost involved. CVSM is prepared by collecting data from company in the prescribed format. All this data thus collected can be consolidated to prepare CVSM. A case study is conducted and a CVSM is prepared in a scaffolding pipe manufacturing unit in Kerala.
Finite Element Analysis of L3-L4 Vertebrae at Various Body Postures Under Osteoporotic Condition
Authors: Resmi S.L , Mohan Ananthu , Firoz N , Hashim V , Dileep P.N
Published: November 2019

The present study gives detailed quantitative information on the biomechanical behavior of osteoporotic vertebra which can be used in the evaluation of osteoporotic bone fracture. A three -dimensional finite element model has been developed and applied for the analysis of the lumbar L3-L4 disc -body unit under various body postures like normal standing, extension, weight lifting, stoop lift and squat lift. The stress and deformation of disc and vertebrae are compared with the corresponding values at 10% and 20% osteoporotic condition. It is observed that for weight lifting, stoop lifting, and squat lift under 20% osteoporotic condition the maximum value of stress obtained is close to compressive strength of the bone. Also noted that fewer than 20% osteoporotic condition the deformation of the disc is increased to 20.08% under weight lifting postures. Therefore,we come to the conclusion that people at old age should avoid risky postures which result in low back pain or lumbar fracture.
Effect of Heat Input on Micro-Hardness and Shear Strength of Inconel 625 Hardfacing onto AISI 347 Steel pipes by GMAW Process
Authors: Rajkumar V. , Arjunan T.V. , Vasan Adithya , Rajesh Kannan A
Published: November 2019

Inconel 625 is one of the most accepted hardfacing material having good corrosion resistance properties at high temperature applications. Hardfacing is the deposition of a hard surface layer to the base metal by means of welding. The benefit of hardfacing is resistance to environmental stresses mainly corrosion at elevated temperatures. Thermal input plays a critical role for manufacturing good hardfaced components with respect to weld bead geometry, cooling rate, etc. In the present study, an L9 orthogonal array of input parameters were carried out with different heat input combinations using 98% Argon + 2% CO2 as shielding gas. Single layer hardfacing was done. The bead-on-pipe welding trials and macroscopic analysis were carried out to find the optimal welding parameters that yielded minimum dilution. The hardfaced layer thickness varies from 1.88mm to 2.58mm on substrate following optimum welding parameters. Visual inspection results reveal that most of welds of higher heat input conditions possess good quality. It is visually observed that width of weld increases with increase in welding heat input. It is noticed that in the range of 200-250 mm/min welding speed and 150A of welding current, good reinforcement and weld bead width at optimum penetration is observed in the experiments. Shear strength test and micro-hardness test were performed over test samples prepared from hardfaced part. Results revealed that both micro-hardness and shear strength of the hardfaced layer were more than that of base metal and values of both increased with increase in heat input. The Inconel 625 hardfaced layer exhibited 32 % higher hardness than the substrate material AISI 347.
Dielectric Properties of Eco-friendly Nanofluids
Authors: Bijuna Kunju K , Shemim S.S.
Published: November 2019

Power and energy sector is adopting the modern technology in all science streams for improving the efficiency after the inclusion of distributed generation and smart grids. The key component in power transmission and distribution is a Transformer. Oil filled transformers are used in High Voltage Transmission and Low Voltage Distribution. To improve the operational efficiency of these huge machines, researches are carried out to prepare insulating oils with high dielectric strength. The present work focuses on the enhancement of dielectric properties of natural oil based insulating fluid by modifying with suitable nanoparticles. The available edible oils such as coconut oil, rice bran oil, sesame oil and sunflower oil are chosen for this purpose. Nanoparticles of TiO2, Fe3O4, SiO2, h-BN and Al2O3 are selected as additives. The properties such as Break Down Voltage, Tan delta and Viscosity are compared for different samples. The values obtained has proved the opportunity to develop natural vegetable base oil with nanomaterial like white graphene having superior qualities compared to the mineral based transformer oil.
Modelling and Analysis of a Progressive Cam Tool for Blade Fuse Holder: A Case Study
Authors: Afzal Asif , Sirajuddin Mohammed , Abdul Razak R.K , Chethan K.M , Avinash
Published: November 2019

Sheet metal segments delivered from press working find wide applications in the territories going from telephonic gadgets to space stations. To design a progressive tool for sheet metal components according to the given details is a testing assignment. This article covers design and modelling of a progressive cam press tool for the component blade fuse holder, which is used in the Printed circuit boards of cars. Few very essential basics of press tools are briefly mentioned. The design and modelling process begins with the careful examination of the component geometry and material specifications. The tool development and modelling of the tool carried out by modelling software Solid Works are provided in detail. Points of interest and detriments of progressive tools over stage tools are additionally spotlighted.
OPTIMAL LAYUP SCHEMES WITH SELECTIVE DISPERSION OF CORE/SHELL MICROPARTICLES IN PLY INTERFACES OF GLASS/EPOXY COMPOSITE LAMINATES FOR LOW VELOCITY IMPACT
Authors: Mubarak Ali M , Joshi Sunil C
Published: November 2019

The overall objective of the investigation presented in this paper was to study the effect of selective dispersion core/shell microparticles (CSP) within the different ply interfaces on impact damage behaviour of glass/epoxy laminates. These laminates were fabricated with the 30 g/m2 CSP particle areal weight per interface. A series of impact experiments were done with instrumental drop tower device at impact energy of 7.8 J and impactor velocity of 2.4 m/s, which is within a practical low velocity impact range. The analysis of the impact load, contact duration indicates that the presence of CSP particles in the bottom layers has a more pronounced effect on the impact performance improvement as compared to the top layers. In the case of selective dispersion, the presence of particles in the middle plies slightly degrades the performance when compared to the selective dispersion of particles only in top or bottom plies.
Effect of laser power on microhardness of NiCrBSi laser clads deposited on AISI410 stainless steel
Authors: Durge Gaurav , Chandak Aayush , Jaiswal Abhimanyu Kumar , Dumpala Ravikumar
Published: November 2019

In the present experimental study, NiCrBSi alloy was deposited on martensitic stainless steel (AISI 410 grade) using laser cladding technique. High power diode laser (HPDL) was used to obtain good fusion, optimum dilution & crack free single track laser clad by varying laser input power (3200 W, 3600 W & 4000 W) while keeping other processing parameters constant. Powders of NiCrBSi alloy with different wt. % of Ni, Cr, B and Si (50HRC & 60HRC) were used in the current study for the deposition. Pre-heating of the substrate was carried out at around 300°C using oxyacetylene flame before deposition in order to reduce the cracks and porosity. Effect of power on microhardness of laser clad was not prominent in the range of power 3200 to 4000 W). In the case of alloy 1 maximum microhardness 692.2 HV0.3 was observed for power 3600 W, while for alloy 2 with power 3600 W maximum microhardness of as-deposited was 755.1 HV0.3.
Determining the formability of AA5052 sheets in annealed and H32 condition
Authors: Sekhar R Anand
Published: November 2019

Forming Limit Diagram (FLD) is an easy and efficient way of determining the safe region for formability in sheet metals. In this work formability of AA5052 H32 sheets of thickness 1 mm is studied by developing a FLD. Since traditional generation of FLDs requires sophisticated equipment, an attempt has been made to generate FLDs using tensile testing and Erichsen cupping tests. Reduced section tensile samples were prepared with varying notch radius of 10 mm and 12 mm for the test. Tensile testing was carried out on a Universal Testing Machine (UTM) with a maximum capacity of 120 kN. Erichsen cupping tests were carried out on rectangular specimens with length of 90mm and widths of 60, 40, 25 and 10 mm respectively. The process (tensile and Erichsen testing) was repeated for this alloy in the annealed conditions with annealing temperature of 345°C. FLDs were plotted for both as-received and annealed conditions. The annealed samples shows a better formability compared to as received samples.
Polyurea Coated Steel Plates For Blast Mitigation In Armoured Vehicles
Authors: Markose Agesh
Published: November 2019

Increasing terror attacks and development of Improvised explosive devices (IEDs) has resulted in the development of protective structures for armored personnel vehicles(APV). These shaped plates either deflect or absorb the energy imparted to them. A well designed plate should absorb the energy as much as possible and transmit the least impulse to the vehicle structure. In this context the response of polyurea coated steel plates have recently been explored with the purpose of increasing the effectiveness of these shaped plates. Experimental studies have shown the capability of polyurea coated steel plates in mitigating the blast load. Hence there is scope for a numerical study on the polyurea coated V-shaped steel plates for finding its response. The objective of this study is to conduct FE based analysis of V-shaped steel plates coated with polyurea. The important parameters which affect the response of the plate are the mass of the explosive, the parameters of the V shaped plate and thickness of polyurea layer. The response variables under consideration are the deflection of the plate and imparted impulse. A numerical procedure validated for flat plates coated with polyurea, has been used for the above study. The results are helpful in identifying an optimal structure design for resisting blast loads.
Is context the hidden spanner in the works of educational measurement: exploring the impact of context on mode of learning preferences
Authors: Fitkov-Norris Elena , Yeghiazarian Ara
Published: November 2019

This paper examines the VARK learning preferences evaluation tool for evidence of context effect as a result of the questionnaire design using a common scenario stimulus to elicit learning preferences. Confirmatory Factor Analysis (CFA) is used to test the overall model fit of a multidimensional hierarchical model which included a context scenario effect and a non-hierarchical model which does not explicitly model a context effect. The results show that half of the scenarios in the VARK learning preferences questionnaire have significant context effect, which in turn introduce response bias. The presence of context response bias in some of the questions offers a possible explanation to the lack of consistent empirical evidence for the existence of preference styles flagged by educators, which contradicts findings from neuroscience and psychology of a convergence effect between learning modality preferences and learning approaches. The findings have significant implications for designers of learning preference tools in particular and educational measurement tools in general as they highlight the risks of the inadvertent introduction of possible response bias when implementing scenario-based evaluation tools.
Musing on extreme quantity values in physics and the problem of removing infinity
Authors: Pavese Franco
Published: November 2019

Many physical quantities display range values apparently extending to infinity (unbounded on one or on both sides). In this respect, unit systems and measurement conventions do not place any constraint to their validity for a maximum (or minimum) value. In general, this happens because such extreme values are far from being reached on the earth or yet are reached in experimental settings. Nevertheless, the issue of extreme values (not in the usual mathematical analysis meaning here) is not irrelevant, since the same units are used also in countless fields of physics, chemistry or technology where extreme values do occur—namely, in the description of the universe in one frame, and in pico/nano-scale or particle physics in another. The issue, of direct interest also of measurement science and specifically of metrology, is discussed here illustrating, as an example, our currently accepted concept of temperature, i.e., the kelvin temperature scale based on Lord Kelvin’s second definition, which encompasses the full range between bounds (0, +∞). In general, the occurrence of infinite values in physical equations, such as singularities in the description of black holes, is a painstaking problem that causes many theories to break down and/or being incapable of describing extreme events. Different methods, such as re-normalization (scaling) or logistic/geometrical, have been used in the assessment of physical observables in order to avoid the undesirable infinity.
Aerodynamic loads acting on the M5/ONERA/IAE aeronautical standard model
Authors: Reis M L C C , Souza M S , Araújo M C C , Santos R R
Published: November 2019

A test campaign to estimate the aerodynamic loads acting on the aeronautical standard model M5/ONERA/IAE is under progress. The model is being tested at the TA-2 subsonic wind tunnel using an external balance. The values of force and moment coefficients and associated uncertainties are evaluated by measuring aerodynamic loads read by the balance sensors and the parameters of the wind tunnel airflow. The campaign is part of an Interlaboratory comparison of results involving other wind tunnel facilities around the world. This paper presents load coefficient curves versus sideslip angle. At TA-2, the uncertainty associated with the pitching coefficient presents the highest value. The dominant contribution comes from the hysteresis.
Multicriteria approach to design of strain gauge force transducers
Authors: Gavrilenkov S I , Gavriushin S S , Godzikovsky V A
Published: November 2019

Force transducers based on strain gauges are ubiquitous in force measuring equipment. Manufacturers of force transducers have to strive for stronger, cheaper and more accurate force transducers in order to compete successfully on the global market. Transducers have to be designed as fast as possible and require as little experimental work as possible. To that end, a reliable design tool is required. In this paper, we propose a new approach to design of force transducers based on strain gauges. The approach is based on the Parameter Space Investigation method and methods of multicriteria optimization. The transducer’s parameters used as design criteria (output signal at rated load, nonlinearity, etc.) are evaluated using Finite Element Analysis (FEA). The FEA results are used to find the optimal locations of strain gauges. This method was implemented in the software system for multicriteria design of force transducers based on strain gauges. The system was used to design a novel force transducer and can be used for developing new strain gauge-based force transducers and optimizing the existing ones.
Solving interdisciplinary tasks: the challenge and the ways to surmount it
Authors: Kneller Vladimir Yu. , Fayans Alexandr M.
Published: November 2019

The paper outlines the first steps on the path to identification and systematization of the types of purposeful activity tasks and to the ways to solve them. The authors have been developing a non-traditional interdisciplinary approach and apply it here to the concept of a task as such. This research area shows a good promise, since it enables the development of a framework for a holistic objective interdisciplinary picture of knowledge in any scientific field. The result of the work is the classification of object types and their characteristics, as well as the classification of the latter in the aspect of their relationship to objective reality. This result points out key directions to the systematization of objects, their related task types, and solution methods.