bluuebunny/crossref_metadata_2025 huggingface dataset:
Construction of dual-axis sun tracker controlled by Arduino
Authors: Alvarez-Herrera C
Published: March 2021

In this work a dual-axis sun tracker was constructed using an Arduino to control two DC electric motors. The motors together with gears move a structure that tracks the sun. To achieve that purpose, an arrangement of four photoresistors was made to input the sun position into the Arduino in form of electric signal. The output signal from the Arduino is used in four relays with their respective optocouplers to transmit power into two DC electric motors to move the tracker. The Arduino uses an algorithm that processes the photoresistors signal and produce it an output signal that is transmitted to the relays. The sun tracker was applied in parabolic dish with good performance.
Thermal and Exergy Evaluation of a Parabolic Solar Cooker for Domestic use at Home
Authors: Terres H , Chávez S , Lizardi A , López R , Vaca M , Lara A , Morales J
Published: March 2021

The results of the thermal behavior and exergy efficiency of a prototype of a parabolic solar cooker are shown. The design and construction of the prototype consider aspects that have not been addressed in other devices of the same nature, such as easy construction and low cost. The results of the temperature reached approximately 96 ° C can be useful for use in domestic applications of cooking and heating food in homes. The evaluation of the efficiencies both first and second law show values less than 45% and 5% respectively and these generate the possibility of carrying out improvements in the solar cooker, which would allow significant improvements to be made in the times required for cooking. and food heating. If the construction-cost relationship of the device is considered, the analysis presented in this work can contribute to its promotion and use in the society that demands alternatives to current and future energy problems.
Energy and exergy analyses of a portable air conditioner system.
Authors: López R , Vaca M , Terres H , Lizardi A , Chávez S , Lara A
Published: March 2021

In this analysis the main objective is to evaluate the thermodynamic behavior of a portable air conditioning system. The power is 4,103 kW. To achieve this, the device was implemented with pre-calibrated thermocouples, taking care that there was always a proper contact with the pipes in order to minimize the differences between the measurement and the actual value. The ESS software and the coolant thermodynamic diagram were used to determine the value of the properties at the considered points. The refrigerant used by this device is the R 410A. Although the first law of thermodynamics can be used to assess the energy consumption, it makes no distinction between quantity and quality of energy. Energy analysis provides only the amount of supplied energy. Exergy analysis provides the maximum useful work that can be obtained by a system that is in balance with the environment. The COP (Coefficient of Performance), turned out to be 7.35, which is acceptable for this type of device. The exergetic efficiency was 4.17. Finally, the hot air flow coming from the condenser was 3.15 kW, this value is significant and will be used in some drying application.
Characterization of a pulsed rhodamine/ethanol dye laser
Authors: García-Villarreal A. , Robledo-Martinez A. , Espejo-Ramos H. , Sobral H.
Published: March 2021

We present here the implementation and characterization of a rhodamine dye laser pumped by a pulsed, high-power solid-state laser. The employed dye consisted of a solution of rhodamine 6G in ethanol at different concentrations. To maximize the laser efficiency the second harmonic of a pulsed Nd: YAG was used to collinearly pump the cavity. In particular, the effect of rhodamine concentration and pump energy on the laser emission were investigated. The laser emission obtained was found to have, on average, a width at half maximum (FWHM) of 12 nm. It was found, for example, that the wavelength of the output line varies linearly with the dye’s concentration. Under the employed experimental conditions, maximum efficiency of 12% is obtained with a concentration of 2.5×10−7 mol/l rhodamine in alcohol.
Lower Limb Design for a Child Test Dummy, based on Osteogenesis Imperfecta characteristics
Authors: Cuautle-Estrada A , Torres-SanMiguel C R , Rivera-Hernández M A , Ramírez O , Urriolagoitia-Calderón G M
Published: March 2021

Active and passive safety have played an essential role in solidifying ground transportation. However, safety-focused on children with some rare diseases is little attacked. This article shows the design of a diseased leg prototype into a crash test dummy Q3, the novelty of this work is based on the morphology and biocompatibility of the lower limbs, which principal characteristics of this prototype replicate the shape of a child with bone-degenerative diseases. In this work, it shows the essential features that a child dummy of this type must contain in order to generate a homologation and approval under the strictest passive safety standards used in the automotive industry. Results show the important kinematics parameters and CAD bones development necessary to conform a new numerical crash test dummy prototype.
Extraction of main elements from a TEM composite laser pattern
Authors: Zúñiga V Torres , Velázquez Aguilar V M , Bañuelos Muñeton J G
Published: March 2021

We examined the atypical formation and superposition of transverse electromagnetic modes (TEM) of high order in a commercial He-Ne laser (@543.5 nm). The competence of the dominant modes exhibits a periodic and stable dynamic, uncommon in industrialized systems. Also, the intensity shows a smooth transition. The origin of the phenomenon is only a product of intra-cavity diffractive components. We found the promotors are a stable optical cavity but quasi-degenerated, with large transversal section (the Fresnel number is irregular), and a breaking the axial symmetry (producing astigmatism). The analysis of the average intensity patterns, and a correlation algorithm — via bi-orthogonal decomposition based on Hermite-Gauss polynomials — expose the five principal TEM elements. These results could be meaningful and inspiring both in courses of optics, laser engineering as in image processing.
Magnetic and Electrical properties of Vitrovac/Au/Vitrovac multilayered obtained by means of magnetron sputtering
Authors: Pinzón-Escobar E F , Montiel H , García A Esparza , Alvarez G
Published: March 2021

We report the effect of the intermediate nonmagnetic layer and the influence of the thickness on the magnetic and electrical properties in Co-based amorphous multilayered, whose composition is VITROVAC-6030/Au/VITROVAC-6030; and these were deposited by DC magnetron sputtering technique. In all samples, the first VITROVAC-6030 layer was deposited on silica glasses substrate, with thickness from 30 to 125 nm, and the middle layer is Au with 5 nm thickness; in top, the VITROVAC-6030 layer was deposited with 30 nm thickness. Additionally, the photolithography process was employed to etch strip patterns on multilayered with length 1 cm and width between 0.1 mm to 1 mm; that it can induce magnetic anisotropy, therefore a change in easy magnetic axis. Finally, we have also made a comparison of magnetic and electrical properties between multilayered and strip patterns on multilayered; where the electrical resistance of multilayered depends on both VITROVAC and Au layer thickness, and electrical measurements show a conductive behavior with high resistance value.
Finding meaning in quadratic equations through a physical context: falling objects motion
Authors: Fallas-Soto R D , Orozco-del-Castillo M G , Perez-Oxté I , Hernández-Gómez J J , Yañez-Casas G A
Published: March 2021

This paper presents the results of the implementation of a design focused on the resignification of the parameters of the quadratic equation (parabolas) through the context of a physical phenomenon. This design was based on an epistemology of practices framed in principles of cognitive and social constructivism, particularly the socioepistemological theory of mathematics education, based also on the model of guided discovery. Based on the students’ arguments, evidence of resignification is shown in the parameters of the quadratic equation in such a way that relationships between algebraic and graphical expressions were established. It was identified that the students’ experiences, as well as the context, were determining elements for success in the resolution of the design.
Alternatives for improving the compressive strength of clay-based bricks
Authors: Jiménez-Quero V.G. , Guerrero-Paz J. , Ortiz-Guzmán M.
Published: March 2021

In this work three alternatives to improve the compressive strength of clay-based bricks were evaluated. Four mixtures were prepared: the control with only CLAY (without any treatment), one single mixture with the ground and screened clay (CLAYGS), one binary mixture in which CLAYGS was partially replaced by fly ash (FA) and one ternary mixture in which CLAYGS was partially replaced by FA plus Sugar Cane Bagasse Ash (SCBA). Apparent densities and porosities (ASTM C-20), initial rates of absorption (ASTM C-67) and compressive strengths (ASTM C-67) were determined. The results showed that the use of CLAYGS has positive effects on the density, porosity and compressive strength of bricks made with this material. Bricks made with CLAYGS were 23.08% denser, 20% less porous and 64.41% more resistant to compression than control bricks. According to the ASTM C-62 standard, the bricks obtained correspond to the MW grade. The partial replacement of CLAYGS with 20% FA improves the quality of bricks made only with CLAYGS and with CLAY. According to the ASTM C 62 standard, the bricks made with binary mixture (CLAYGS+FA) have the compressive strength required to be considered SW grade bricks. The addition of SCBA in binary bricks negatively affects their compressive strength.
Effect of the position of the internal reflectors on the thermal operation of a solar cooker box-type
Authors: Terres H , Chávez S , Lizardi A , Alvarez E
Published: March 2021

The results of the effect that five internal reflectors have on the operation of a box-type solar cooker are shown. Variations in the angular position of the reflectors generate new dimensions for the cooker. For this reason, in order to carry out the comparison of four solar cookers with different dimensions under the same operating conditions, it is used the numerical simulation that allows obtaining the representative temperatures that describe the thermal operation of the solar cooker. The temperature values achieved and expressly referred to the heating of 1 liter of water are obtained from the numerical solution of a mathematical model under initial conditions. The results show that for a tilt of the reflector angles with respect to the horizontal of 40°, 50°, 60°, 70° and 81° the highest values of the water temperature are obtained, specifically, the highest value among these is 98.1 ° C. While for reflector inclinations of 13°, 18°, 21°, 24° and 30°, there are the lowest temperature values and among these, the highest value is 83.9 °C. The results, together with their discussion, contribute to the knowledge of the behavior of the components of box-type solar cookers.
Data Mining applied to interventional cardiology procedures
Authors: Toledo M R , Vázquez E R , García-Salcedo R , Gómez-Vargas I , Uruchurtu E S , Rivera-Montalvo T
Published: March 2021

The diagnosis in the cardiological treatment is fundamental. Computational algorithms allow to analyse better the available medical data from a huge number of patients and use it to improve the diagnosis mechanism. In this work data from several patients of a Mexican cardiological Institute was recollected and prepossessed to analyse it with a data mining technique called clustering.
Optical properties of InAs quantum dots embedded in InGaAs/AlGaAs/GaAs structures with different capping layers
Authors: Cisneros-Tamayo R , Torchynska T , Casas-Espinola J L , Polupan G , Reséndiz-Chincoya M
Published: March 2021

The InAs quantum dots (QDs) embedded in Al0.30Ga0.70As/InGaAs/AlGaInAs/Al0.30Ga0.70As structures and covered by strain reduced AlGaInAs capping layer have been investigated in as grown state by means of a photoluminescence method. Three types of QD structures with different QD capping layers: GaAs (#1), Al0.10In0.15Ga0.75As (#2) and Al0.40In0.15Ga0.45As (#3) are compared. It is revealed that the QD emission in the structure with Al0.10In0.15Ga0.75As capping is characterized by the highest PL intensity of the ground state (GS) band and smaller the full with at half maximum (FWHM), compared to #1 and #3 structures. The variation of the GS emission peak versus temperature has been monitored within the range of 10-500K for the as grown film states and compared with shrinkage of the energy bandgaps in the InAs and GaAs bulk crystals. The results show that the efficiency of Ga/Al/In intermixing in #2 and #3 is less than in #1. Finally, the peculiarities of PL spectra of the studied QD structures have been analyzed and discussed.
Design of a method for the evaluation of natural and anthropic radionuclides in Chilean soils
Authors: Mera E , Correa R , Camacho E , Osorio R , Godoy S , Donoso S
Published: March 2021

The present work search to design a method for the evaluation of natural and anthropic radionuclides in Chilean soils, for which the international literature was reviewed, a hybrid method is generated product of the literature analysis and equipment availability in Chile, and is executed an example based on the recommended method.
Modeling of cloudiness based on the difference between the theoretical solar irradiance and the real solar irradiance on the earth’s surface for the installation of photovoltaic energy projects
Authors: Mera E , Pacheco P , Parodi C , Gutiérrez L
Published: March 2021

Considering that the solar irradiance on the surface is a direct indicator of cloudiness [1], we proceeded to make a model that determines the cloudiness, contrasting the differences that are generated between the theoretical solar irradiance estimated on the surface [1] [2] and real solar irradiance recorded on the surface. To evaluate the quality of the model, the real cloud values and the estimates were contrasted in a dispersion diagram, both in eighths at the daily average level, obtaining a correlation coefficient of 0.7. The modeling of cloudiness is a relevant variable for the installation of photovoltaic energy projects.
On the activation energy for plastic flow during tension test at room temperature and the anisotropy behaviour of Ti-6Al-4V alloy
Authors: Muñoz-Andrade J D , Aguilar-Sánchez M
Published: March 2021

The movement of dislocations inside of crystals during the tension test at constant crosshead velocity is related to activation energy for plastic flow in spatially extended polycrystalline systems. In this work, the main objectives are to establish the influence of the slip systems forαhexagonal compact packaging (hcp) titanium phase on the activation energy for plastic flow and the anisotropy influence on the plastic flow behaviour of Ti-6Al-4V alloy in sheet form under tension test at constant crosshead velocity of 1 mm/min in three in-plane orientations, namely in the rolling 0° (RD), 45° (DD) and transverse (TD) directions, respectively. By applying the quantum mechanics and relativistic model (QM-RM) proposed by Muñoz-Andrade, it is shown that for a  pyramidal type slip with a Burgers vector b=0.553 nm, the activation energy barrier for plastic flow at maximum stress in uniaxial tension in the sheet rolling direction, Q=115.115 kJ/mol is lower in comparison with Q=116,629 kJ/mol obtained by the  basal type slip with a Burgers vector b=0.295nm. These results are in accordance with the reduced cross-slip activation energy barrier for cross-slip onto pyramidal planes in an a hexagonal crystalline structure with compact packaging (hcp) titanium phase. Additionally, it was shown that transverse direction (TD) of Ti-6Al-4V alloy in sheet form has developed the maximum stress in uniaxial tension test and ductility.
Structural and TL glow curve of GdAlO3 perovskites
Authors: Alonso A , Rivera T , Barrera A , Zárate J
Published: March 2021

TL glow curve of any semiconductor is the patterns that mean when a material is suitable as Thermoluminescent (TL) material. Gadolinium aluminate (GdAlO3) perovskites have several properties that can be propose it as a good host for thermoluminiscent materials. GdAlO3 perovskite powder was synthesized by coprecipitation method and the powders were analyzed by characterization techniques. The Differential scanning calorimetry study showed changes in crystalline phases at 900 °C and 1084 °C during the calcination process. The first change of crystalline phase was identified by X rays diffractometry technique as a change from GdAlO3 hexagonal to GdAlO3 orthorhombic. TL glow curves of GdAlO3 under ultraviolet (UV) 256 nm and beta radiation effects were observed as crystallite size was increased.
Design of a test bench for a sternum prosthesis
Authors: Ramírez O , Torres-SanMiguel C R , Cuautle-Estrada A , Rivera-Hernández M A
Published: March 2021

The present work shows the three-dimensional design and the simulation of movements in a test bench to reproduce the respiratory cycle in human beings so that the useful life of a sternum prosthesis can be evaluated. A design methodology was used to identify the requirements and subsequently establish the design and selection of the elements. Among the most relevant parameters to consider in the design, the test bench is required to simulate the action of the forces on the prosthesis, which are generated during the respiratory cycle in humans, causing expansion of the rib cage and rib elevation. Additionally, the test bench is capable of applying a compression force to the thorax that produces a seat belt in an automobile to reproduce impact scenarios. The test bench has linear actuators to control the required action force and the applied displacements. Simulations results show that the test bench is capable of reproducing movements on the sternum during the respiratory cycle together with impact conditions, as well as the reliability that the test bench can be used to perform tests that require a high time.
On the onset of thermalization in closed few particles systems: Classical and quantum results
Authors: Hernández-Saldaña H
Published: March 2021

A study of quantum-classical correspondence for the onset of thermalization in an isolated system of four interacting particles is presented. Provided that classical dynamics of the system is chaotic, thermalization is present and fits the expected statistical mechanics results. Quantum classical correspondence is established for the classical analogue of the single particle distributions of occupation numbers. The latter quantity is useful to test thermalization and it allows to obtain the microcanonical Boltzmann factor in the quantum and semi-classical cases. The correspondence between them and the statistical mechanics results are surprisingly good considering that we have only four interacting particles. The resulting Boltzmann factor for the occupation number distribution depends on the eigenfunction width, which is a semi-classical parameter explicitly calculated and consistent with the quantum one.
Non-face-to-face physics laboratory, an educational strategy
Authors: Granados J , Tavera F , Cid A , Hernández R T , Velázquez J M
Published: March 2021

Under the health emergency implemented in Mexico City, due to pandemic caused by COVID19, and the measures to protect the population organized by the Secretaría de Salubridad and Federal Government, the face-to-face classes at all levels of education were suspended. This situation lasted for several months, so, in the case of the Universidad Autónoma Metropolitana, UAM, it was decided to continue conducting academic activities remotely. This decision brought an additional problem since some subjects taught in engineering careers cannot be implemented for the student to carry them forward at home. This is the case with physics labs. Situation that led to this educational research. The issue to solve is How can you teach Physics Lab in a non-in-person way? In this paper we describe how the objective was achieved, specifically in the Learning Teaching Unit, UEA, Laboratory of Rigid Body and Oscillations. Using Information and Communication Technologies together with the use of Video and Video Analysis Software, a working method could be implemented in which all the stages of experimental work were carried out. The results of the activities carried out at home by the students, communicated in the respective written reports, show that the proposed method for remote teaching of Laboratory of Physics is feasible and allows to carry out the process of non-face-to-face teaching at the higher education level.
Theoretical study of the movement of a mobile object in different trajectories with a coupled pendulum
Authors: Espíndola R , Valle G Del , Hernández G , Muciño D
Published: March 2021

Coupled systems are studied within classical mechanics. In this work, using the formulations of classical mechanics, such as the Lagrange and Hamilton formulations, we analysed the system composed of an object of mass M in motion, to which a pendulum of length l and mass m is coupled. We studied the movement of the object when it moves in a single dimension (y direction) with pendulum oscillations: 1) in 2D (zy-plane) and 2) 3D (surface xyz). Subsequently, the movement of the object is studied when it moves in a circle of radius R with the same oscillation conditions referred to for the pendulum.
Motion equations of a pendulum gear system
Authors: Díaz P. , Cid A. , Granados J. , Velázquez A. JM , Velázquez J. A.
Published: March 2021

This work presents a dynamic system that is composed of gears which have an angular velocity

θ
˙

. Each of the gears was added a rod of known length and mass which can move freely. This system can move in such a way that the rods oscillate as the gears rotate. With the Lagrangiana formulation, the motion equations that govern the system were built, differential equations were solved with standardized numerical methods and graphs were obtained in different phase spaces.
Evaluation of “X2” delination well drilling project block on oil service company
Authors: Sardjono W , Lahlianti RC , Hobri  , Tohir M , Mukhlis M
Published: March 2021

Project is an activity or business that is temporary and has a certain period of time, unique and produces a product, service or both. Achieving project activity right on the schedule was an important thing for project owners or contractors. However, the schedule of the "X2" Well Drilling Project has delayed from the original plan due to several inhibiting factors. Therefore, the cost’s project increased during project implementation. The factor analysis method is used to reduce the number of independent variables until new variables are found which are then examined for their relationship and a mathematical model is built using the regression analysis method. The location of this research was one company with 100 valid respondents. The results of this study indicate that there are 3 (three) new factors that have a positive effect and 1 (one) new factors that have a negative effect on the condition of the differences that occur. If a project can be completed before the work period ends, at other times if the owner wants to build a construction project again, there is no doubt that the owner will re-choose Oil Service Company to work on another Drilling Project.
Timing pulse code modulation as a tool for quantization noise reduction in special-purpose IT systems
Authors: Hordiichuk V , Shyshatskyi A , Korchinskyi V , Kildishev V , Pozdniakov P
Published: March 2021

The aim of the article is to examine the issue of eliminating quantization noise in the process of analogue-to-digital conversion by means of timing pulse code modulation. According to the results of the method proposed, it has established that the use of timing modulation significantly increases the number of sampling levels at a given interval without reducing the duration of individual code pulses, that, in its turn, significantly improves signal quality (readability) after the digital-to-analogue conversion on the receiving side.
The influence of electromagnetic waves and laser fields on conductivity tensor for the case of electron - optical phonon scattering in quantum wells with a parabolic potential
Authors: Ngoc H V
Published: March 2021

This paper studies the influence of electromagnetic waves and laser fields on conductivity tensor with the case of electron - optical phonon scattering in quantum wells. Because electrons are confined in the quantum well in one direction, the conductivity tensor in the quantum well is different from the conductivity tensor in the bulk semiconductor. The carrier system in a quantum well is located in an electromagnetic wave field and a laser field. Using quantum kinetic equation for electrons in quantum wells in the presence of an electromagnetic wave and a laser field, from the quantum kinetic equation it is possible to calculate the conductivity tensor. The conductivity tensor expression is a function of the electromagnetic wave frequency, laser field frequency and quantum well characteristic parameters. Survey and plot the dependence of conductivity tensor on electromagnetic wave frequency, laser field frequency, laser field amplitude with GaAs / GaAsAl quantum well case.
Development of mathematics learning tool based on open-ended with jumping task and the effects on creative thinking ability of junior high school students
Authors: Ummah B I , Susanto  , Hobri  , Solehah A
Published: March 2021

This study aims to develop a learning tool based on open-ended with jumping task on the material of the system of linear equations in a two variable for grade VIII junior high school students and to determine the effects on students’ creative thinking ability. This research was mixed method, which combines qualitative research and quantitative research. The development model used in this research is Thiagarajan which goes through four stages, namely define, design, develop, and disseminate. Meanwhile, for experimental research using quasi experimental design, namely pretest-posttest for non equivalent control group design. The subjects of this study were students of Islamic Junior High School Wahid Hasyim Balung. Two classes were selected as the research sample, class 8A as the experimental class and class 8B as the control class. Students’ creative thinking abilities were measured using tests of creative thinking ability. The results showed that learning tool based on open-ended with jumping task met the criteria of validity, practicality, effectiveness, and had a significant effect on students’ creative thinking ability.
Development of lesson study for learning community based learning tools using google classroom media and its impact on students’ creative thinking skills
Authors: Hasanah N , Hobri  , Fatekurrahman M , Kusuma M A , Hadiyanti N F D
Published: March 2021

Learning mathematics is a science that is learned as a very important basis for everyday life the lesson study for learning community learning process that prioritizes group learning that involves peers in learning so that the creative thinking process between students increases. Along with the development of very sophisticated technology demands online-based learning to facilitate the learning process and able to support students’ creative thinking which can be measured from fluency, flexibility, originality and elaboration. The research aimed to develop lesson study for learning community based learning tools using google classroom media on three-variable linear equations material for X grade high school students and to determine the effect on students’ creative thinking abilities. This research uses a mix method with a sequential Explorstorydesign combination model with a thiagardjan development model through the 4D domain, which are define, design, develop and deseminate inexperimental research using the nonequivalent control design with the results obtained from the pretest value functions to determine the initial knowledge and posttest for knowing knowledge after being given treatment. The results showed that the lesson study for learning community based learning tools using google classroom media were valid, practical and effective and had a significant impact on creative thinking.
Development of mathematics learning tools with Realistic Mathematics Education-Jumping Task (RME-JT) and its effect on the mathematic communication skills
Authors: Sa’id I A , Pambudi D S , Hobri  , Safik M , Insani K
Published: March 2021

This research focus on the development of learning based on realistic mathematics education approach with Jumping Task questions. The develop learning are related to the real life of students, so that students can be expected to enjoy and like mathematics. The develop learning consist of lesson plan, worksheet, and learning test. This research used mixed method, both combine development and quantitative research. The model study is Thiagarajan 4D by using independent test analysis. The results showed that realistic in learning mathematics education approach-Jumping Task has a good quality practice, efektive, and fulfill the criteria of validity. On learning process using realistic mathematics education approach, the students are more active, enthusiasm and motivation so that it has a positive impact in improving students’ mathematics communication. Significant value is 0.000 (p <0.05)..
Developing of learning tools based on science, technology, engineering, and mathematics (STEM) based on learning community to improve critical thinking ability in class X student’s arithmetic sequences and arithmetic materials
Authors: Insani K , Hobri  , Prihandoko A C , Sa’id I A , Safik M
Published: March 2021

This study aims to develop learning-based tools science, technology, engineering, and mathematics (STEM) based on learning communities for improve critical thinking skills in arithmetic sequence and series material. The learning tools developed were RPP, LKS, and THB. Method which used is development with the Thiagarajan development model through four stages, namely define, design, develop, and disseminate. The subjects of this research are students SMKN 2 Bondowoso class X. Students’ critical thinking skills are measured using learning outcomes test. This research is to describe the development process and test results validity, practicality, and effectiveness. The results of this study produce a device learning that meets valid criteria which is practical, and effective.
Developing gamification based biology learning materials for senior high school students in industrial agricultural area in jember, indonesia
Authors: Siswati B H , Prihatin J , Kuswati  , Damayanti A F , Nafisah L
Published: March 2021

This research aimed at describing the feasibility of gamification-based biology learning materials for senior high school students in the industrial agricultural area in Jember, Indonesia. The feasibility was based on the content validity, construct validity, and student responses. The development procedure of the learning materials used Plomp’s development model which consisted of the preliminary investigation - design - realization - test, evaluation, and revision – implementation stages. The learning materials developed in this research were the syllabus and lesson plans, material modules, gamification modules. The research data were collected using interviews, observation, tests, questionnaires and documentation. The feasibility of the developed learning materials obtained very feasible criteria based on the average score by the expert team. Therefore, it can be concluded that the learning materials developed in this research are very feasible to be implemented in schools viewed from the content validity, construct validity, and student responses.
Early detection of the financial crisis in Indonesia, Thailand, and South Korea based on real exchange rates
Authors: Ratnasari A , Sugiyanto  , Sulandari W
Published: March 2021

The 1997 Asian financial crisis and the 2008 global financial crisis had a significant impact on the economies of various countries, including Indonesia, Thailand, and South Korea. Therefore, this study aims to detect early financial crises in these three countries based on real exchange rate indicators. The early detection of financial crises, relevant institutions in applying appropriate policies. Thus, financial crises can be avoided. The real exchange rate indicator contains fluctuations, and changing conditions. As a solution, the volatility models, i.e. autoregressive conditional heteroscedasticity (ARCH) and generalized ARCH (GARCH) explains volatility or fluctuations, and Markov switching (MS) explains changing conditions. The combination of these models yields a smoothed probability value used for detecting financial crises. The real exchange rate of Indonesia, Thailand, and South Korea data against the United States were used from January 1990 to March 2020. The results showed that MSARCH( 2,1), MS-ARCH(2,1), and MS-GARCH(2,1,1) are for Indonesia, Thailand, and South Korea, respectively. The real exchange rate indicator can detect crises in Indonesia and South Korea in the 1997 and 2008. Whereas in Thailand, it was only able to detect crises occured in the 1997. The prediction results of the smoothed probability showed no signal of the financial crisis in Indonesia, Thailand, and South Korea one year later.
Data literacy of high school students on physics learning
Authors: Suryadi  , Mahardika I K , Supeno  , Sudarti
Published: March 2021

Data literacy is the ability to collect, understand, manipulate, and use data. Based on the viewpoint of cognitive skills, data literacy is related to the ability to collect, filter, select, analyse, interpret, critique, visualize, and communicate data. This ability is essential for students to have, especially in solving learning physics and everyday life problems. Data literacy is indispensable in the life of the modern world like today. Students who have good data literacy will understand and assess data critically, whether presented in tables, graphs, or charts. The purpose of this study is to determine the data literacy of high school students in physics learning. Data were collected through the measurement of data literacy using written tests. Measured data literacy included students’ ability to collect, analyse, interpret, implement and evaluate data as well as assess data quality. The results show that high school students’ data literacy in physics learning is still in the unsatisfactory category. Various efforts must be made so that data literacy for high school students can be develop, i.e., by implementing learning strategies and using appropriate learning resources. Another action that can be done is to apply a teaching model that follows the characteristics of 21st-century learning.
Developing textbook based on scientific approach, critical thinking, and science process skills
Authors: Rofieq A , Hindun I , Shultonnah L , Miharja F J
Published: March 2021

Several researchers have done the development of textbooks as a source of learning. However, most only partially develop students’ academic abilities. This study aims to develop biology textbooks based on a scientific approach to improve students’ critical thinking and process skills. This mix-method research consists of research development and quasi-experiment. Model development refers to modifying the Borg & Gall development model, which consists of preliminary studies, model development, and model testing, whereas the quasi-experiment uses the pretest and posttest groups design. This study’s population were all students of Kepanjen Islamic High School, while the sample involved was 24 students of class X MIA. The data collection method used expert questionnaire validation, pretest, and posttest. Data analysis used the dependent t-test with a significance level of α = 0.05. The model test results show that there were significant differences in the average between pretest and posttest scores. Besides, the validation test results indicate that teaching materials were declared appropriate and effective in learning.
Development of mathematics e-module with STEM-collaborative project based learning to improve mathematical literacy ability of vocational high school students
Authors: Hadiyanti N F D , Hobri  , Prihandoko A C , Susanto  , Murtikusuma R P , Khasanah N , Maharani P
Published: March 2021

The research conducted was a research on media development in the form of electronic module in mathematics learning using a STEM-Collaborative Project Based Learning model which is believed to improve the mathematical literacy skills of vocational high school students. The test subjects in this study were students of Vocational High School 1 Panji Situbondo where the data analysis technique used in this development research was descriptive analysis techniques. The quantitative data that had been obtained from the Likert scale measurement were converted based on the weighted score that has been determined. This data is quantitative data which were further analyzed by descriptive statistics. The scores obtained from the questionnaire were then converted so that the eligibility percentage was known and the conclusion that the e-module developed was valid, practical and efficient. The benefit that could be obtained from this research was the contribution of thoughts to improve the quality of education, especially in mathematics learning by presenting new insights regarding the preparation of learning tools in the form of e-modules as an alternative to learning media for mathematics to improve the quality of the learning process.
The development of maritime-based educational games for mathematics learning media
Authors: Jatmiko D D H , Hobri
Published: March 2021

This research was intended to develop the Android-based learning media on the system of linear equations in three variables whose theme was maritime. The results of this learning media development were reviewed based on the validity, practicality, and effectiveness. The instruments used were the media validation sheets, material validation sheets, students’ responses questionnaires, and test scores on the students’ learning outcomes. The learning media testing was given to the students of grade X at SMK Negeri 4 Probolinggo. The results showed that it was classified as the “excellent” category. The average scores of total validity obtained were 4.43 out of 5 on the learning media experts; it was then into “very valid” category. This learning media was considered very practical since the average score obtained on the students’ responses questionnaires was 4.49 out of 5. According to the test on the learning outcomes, 93.33% of the total number of students in grade X KTPI 1 scored ≥ 70 as the minimum scores. Hence, it can be said that this learning media was effective. The conclusion drawn from the research results revealed that maritime-themed educational games for mathematics learning media were valid, practical and efficient.
An analysis of undergraduate students’ higher order thinking skills in Geometry
Authors: Safrida L N , Susanto  , Setiawan T B , Ambarwati R , Hussen S
Published: March 2021

Higher order thinking skill (HOTS) becomes important thing and issue in teaching and learning, especially in Mathematics. By using HOTS, students could solve the complicated problems and situation that could be used in real life. So that, the students could be ready to encounter high technology developing and industry revolution 4.0. Then, students could compete with foreign students. The purpose of this study is to describe the higher order thinking skills’ students in proving geometry theorem. This study uses qualitative research and conducted to the undergraduate students. The result of this study shows that the highest HOTS score equal to 80 and the lowest HOTS score equal to 30, then the average of HOTS score is 62. The subjects with low score, only try to analyse the statement without clear reason. The subjects with medium score begin to analyse and evaluate the problem with reason although it’s not clear enough. The subjects with high score begin to create new idea in proving theorem although sometimes could explain the reason. At the end, they could draw the conclusions based on the problems.
Increased extreme rains intensify erosional nitrogen and phosphorus fluxes to the northern Gulf of Mexico in recent decades
Authors: Tan Zeli , Leung L Ruby , Li Hong-Yi , Tesfa Teklu , Zhu Qing , Yang Xiaojuan , Liu Ying , Huang Maoyi
Published: March 2021

Soil erosion delivers enormous amounts of macro-nutrients including nitrogen (N) and phosphorus (P) from land to rivers, potentially sustaining water column bioavailable nutrient levels for decades. In this study, we represent erosional N and P fluxes in the Energy Exascale Earth System Model (E3SM) and apply the model to the continental United States. We estimate that during 1991–2019 soil erosion delivers 775 Gg yr−1 (1 Gg = 109 g) of particulate N (PN) and 328 Gg yr−1 of particulate P (PP) on average to the drainage basins of the northern Gulf of Mexico, including the Mississippi/Atchafalaya River and other rivers draining to the Texas Gulf and the Eastern Gulf. Our model simulation shows that in these rivers PP is the dominant P constituent and over 55% of P exported by erosion comes from soil P pools that could become bioavailable within decades. More importantly, we find that during 1991–2019 erosional N and P fluxes increase at rates of about 15 Gg N yr−1 and 6 Gg P yr−1, respectively, due to increased extreme rains in the Mississippi/Atchafalaya river basin, and this intensification of erosional N and P fluxes drive the significant increase of riverine PN and PP yields to the northern Gulf of Mexico. With extreme rains projected to increase with warming, erosional nutrient fluxes in the region would likely continue to rise in the future, thus complicating the effort of reducing eutrophication in the inland and coastal waters.
Energy absorption and deformation pattern analysis of carbon fibre reinforced composite crash box under frontal load model
Authors: Primawan Prayoga Bintang , Choiron Moch. Agus , Purnowidodo Anindito
Published: March 2021

Crash boxes as a passive safety system in vehicles had been developed to produce high energy absorption performance. This study investigates the influence of cross-section geometry and fibre orientation angle on the composite crash box design to determine deformation pattern and energy absorption performance. The cross sections studied are circles and squares with variations in fibre orientation angles 0°, 15°, 30°, 45°, 60° and 75°. Carbon Fibre Epoxy CFS003 / LTM25 Prepegs with the type of plain woven fibre used to model crashbox structures. The computer simulation test model was carried out using a frontal load model with velocity of 7.76 m s−1. The results showed a circle cross-section at each variation of the orientation angle has a higher energy absorption than a square cross-section. Deformation patterns in each model show different characteristics including fragmentation mode, lamina bending, brittle fracturing, and local buckling as well as a combination of several patterns. The highest energy absorption obtained in the C60 model was 3.664 kJ with Specific Energy Absorption (SEA) of 36.799 kJ kg−1 and a CFE value of 0.59. While the lowest energy absorption occurs in the S45 model with 1.287 kJ which has a SEA value of 12.667 kJ kg−1with a CFE of 0.49. The CFE value indicates that the model with a circular cross section has better crushing stability than a squarecross section.
Deformation pattern and energy absorption of polylactic acid (PLA) carbon crash box under quasi static loading
Authors: Bintara Redyarsa Dharma , Choiron Moch. Agus
Published: March 2021

The purpose of this study is to investigate the deformation pattern and of energy absorption (EA) in Polylactic Acid Carbon Crash Box. The crash box specimen was produced by using 3D printer machine. The quasi static testing method is performed to compress the specimen with a speed of 2 mm min−1 using universal testing machine. It was pressed until it reaches deformation of 80 mm from its original length of 120 mm. The deformation was analyzed in three different variations of wall thickness (Wt), 1.6 mm; 1.8 mm; and 2 mm. The deformation pattern and the maximum EA are analyzed to determine the best design specifications. The results show that the highest EA occurs on Wt 2 mm (357.986 J), whereas the lowest EA occurs on Wt 1.6 mm (224.012 J). The local buckling and discontinue folding consist on three model of crash box. In addition, the fragmentation is also formed on Wt 2 mm of crash box but it is not looked on remain models.
Identification of damage in a ship hull sandwich plate by natural frequency
Authors: Ariesta Rizky Chandra , Zubaydi Achmad , Ismail Abdi , Tuswan  , Al-Syachri Mohammad Zircham
Published: March 2021

The damage of the sandwich plate occurs in the core material identification used for modal analysis on the ship hull using finite element analysis. This analysis detects the effect of damage. Five varied models using different damage percentage size is developed to ensure whether the hull is appropriate. This paper investigates the influence of the increasing damage percentage on the sandwich plate using the based natural frequencies as a parameter to determine the location of the damage. Five cases are being simulated for the damage. The location of the damage modelling used utilizing FEA software to adapt to the problems. Moreover, the sensitivity influence of percentage damage size, boundary condition, and application of spring element on the natural frequency behaviour of damage identification is also executing. The damage is detected by comparing the natural frequency reduction of the intact and damaged plate using free vibration analysis. The mode shape of the sandwich plate displayed to observe the location of damaged. The results show that the damage in the sandwich plate decrease the natural frequency and influence the mode shape, and evaluating both reveals the location of the damage.
Fatigue simulation with pedalling load and vertical load for city bike frame following British standard EN 14764
Authors: Wikarta Alief , Wahyudi Tambun Edwin Togi
Published: March 2021

The frame supports both the load from the rider and the riding conditions. When the loading conditions occur repeatedly, the bicycle frame will experience fatigue failure. This study discusses the fatigue simulation for city bike frames made of titanium, intending to know the safety factor and the service life of the bicycle frame according to a pedal load and a vertical load following British Standard BS EN 14764. The bicycle frame used for this research is a frame for the city bike type, where each composing tube of the bicycle frame has a thickness of 1.2 mm. The pedalling load applied to each pedal is repeated downward with 1000 N. While the dynamic load vertically downwards with a force magnitude from 0 to +1000 N. The results of the fatigue test simulation with each type of loading indicate that the titanium material with 1.2 mm thickness is overdesigned. Therefore, it is necessary to modify the bicycle frame by reducing the thickness of the frame to 1 mm on each tube. The safety value of the resulting fatigue simulation shows a decrease due to the reduction in thickness, however it still safe in terms of the material strength limit. The resulting bicycle frame after modified is lighter, where the initial mass was 6.79 kg and reduce to 3.92 kg.