bluuebunny/crossref_metadata_2025_split huggingface dataset:
Optimal relations for the allocation and effectiveness of the heat exchangers (hot and cold side) of an irreversible regenerative Stirling cycle
Authors: Alanis-Padrón R , Aragón-González G , León-Galicia A , Morales-Gómez J 
Published: March 2021

Abstract
A stationary irreversible regenerative Stirling cycle model, with two sources of irreversibilities (finite rate of heat transfers and heat leak), is analyzed. The aim of this work is to obtain the criterion of partial optimization presented in [3]. Since with this criterion, the optimal relations for the allocation and effectiveness of the heat exchangers of Carnot-like power plant are obtained; when two design rules are applied, alternatively: internal thermal conductance fixed, or areas fixed. These optimal relations are the same for maximum specific power and efficiency. As an instance, after the substitution of these optimal values in the specific power and efficiency, the maximum specific power and efficiency are obtained. Then the maximum efficiency and specific power are compared, and it is found that the maximum efficiency is greater than maximum specific power for both design rules.
Molecular dynamics for Ti-Ni dimer adsorbed on pristine and defective graphene
Authors: Arellano J S , Cruz Guerrero Harum Hueman 
Published: March 2021

Abstract
Motivated by the oxidation and corrosion processes of the nitinol alloy that has been used in biological applications, we show initial first principles calculations for the interaction of the Ti-Ni dimer, the simplest nitinol alloy, with a graphene layer, (gl). We have selected the graphene layer for the interaction, because our results can be compared with similar results for the interaction of many substances with a graphitic system as the gl. The results of several relaxations of the system Ti-Ni-gl shows that the dimer has been adsorbed to the gl. Temperatures of 300, 800, 1100 and 1300 K are not enough to desorb the dimer from the gl, these results are obtained from the molecular dynamics for those temperatures. The metallic character of the system is obtained from the density of states and projected density of states. Similar results are obtained for the interaction of the dimer when there are one or two carbon vacancies on the gl.
Characterization by FTIR spectroscopy of degradation of polyethylene films exposed to CO2 laser radiation and domestic composting
Authors: Martínez K I , González R , Soto J J , Rosales I 
Published: March 2021

Abstract
Polyethylene (PE) is a non-biodegradable polymer and accumulate easily on environment due its high molecular weight. In order to reduce this problem low-density (LDPE), high-density (HDPE) and biodegradable (BIO-PE) polyethylene films were exposed to CO2 laser radiation at different fluences and to domestic composting, the effects of CO2 laser radiation and domestic composting were characterized by FTIR spectroscopy. LDPE, HDPE and BIO-PE exposed to CO2 laser radiation underwent thermodegradation reactions causing changes in LDPE, HDPE and BIO-PE chemical and physical properties due to chain scission. LDPE, HDPE and BIO-PE biodegradation reactions leading to the formation of carbonyl (C=O), vinyl (CH2=CH) and hydroxyl (OH) groups.
Partial feedback linearization for a path control in a gantry crane used in lifting machinery in civil engineering
Authors: Ospina-Henao P , Carrillo-Suárez A , Guarín-Martínez L , Ortíz-Blanco A , Peñaranda-Vega J 
Published: March 2021

Abstract
This paper presents an alternate form for the dynamic modelling of a mechanical system that simulates in real life a gantry crane type, using Euler Lagrange classical mechanics, which allows find the equations of motion that our model describes. In order to verify the theoretical results obtained, a comparison was made between solutions obtained by simulation in SimMechanics-Matlab and Euler Lagrange equations system, has been solved through Matlab libraries for solving equations systems of the type and order obtained. Based on the partial feedback linearization, an improved nonlinear controller is analyzed and designed for the movement of an overhead crane or industrial shed. Three control inputs composed of bridge movement forces, carriage displacement, and pendulum or load angle are used to handle the state variables consisting of bridge movement, carriage movement, load displacement, and angle of turn of the same. The objective is to bring the mass of the pendulum from one point to another with a specified distance without the oscillation from it, so that, the answer was overdamped. The asymptotic stability of Lyapunov is also studied and the control scheme is of position of the load, constituted by the non-linear feedback of the actuated and non-actuated states. To verify the quality of the control process, verify numerical simulations. The proposed controller asymptotically stabilizes all states in the system.
Ab initio simulation of the effects of substitutional doping of oxygen in the semifullerene (C30)
Authors: Canales-Lizaola M , Ramirez-de-Arellano J M , Arellano J S , Magaña L F 
Published: March 2021

Abstract
Using first principles calculations, we studied the effects of substitutionally doping a 30-atom semifullerene (C30) with oxygen atoms, within the Density Functional Theory (DFT) and the pseudopotential formalism. We analyzed two C30 structures, one with a pentagonal and one with a hexagonal base. In both cases, the substitutionally absorbed oxygen atoms break the bonds between pentagons and hexagons of the semifullerene. We show that each semifullerene breaks into two geometrically flat structures, one of them being consistent with a known ring isomer of the fullerene C20. We used the Quantum ESPRESSO package code and the generalized gradient corrected Perdew-Burke-Ernzerhof (PBE) approximation for the exchange and correlation functional.
Phonocardiography in an Echocardiography room
Authors: Granados J , Rodríguez J A , Tavera F , Cid A , González A M , Hernández R T , Velázquez J M 
Published: March 2021

Abstract
In Mexico City at Universidad Autónoma Metropolitana Azcapotzalco (UAMA), with the aim to build a Computerized Diagnostics System of Cardiac Diseases based on the sound emitted by the heart, a research project is conducting. Cardiac sound is captured in a computer through a data acquisition system which it transforms in an image that will be analyzed later. Along years, several methods had been developed in different institutions of various countries looking for identify in phonocardiograms cardiac pathologies, some of them using complex mathematical algorithms for medical sector, which make difficult to understand and apply. At UAMA we can recognize image alterations of acoustic wave by means of a visual and computerized method in which its possible identify possible damages in the different heart’s components. To get a set of images of phonocardiograms of people with different heart disease, diagnosed and being treated, phonocardiograms were taken to ambulatory patients seen in the Echocardiography office at a High Specialty Hospital. We show the obtained images and his correlation with the diagnosed cardiac diseases.
Numerical 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

Abstract
Coupled systems are studied within classical mechanics, we study and analyse numerically the movement of the mobile object when it moves in a single dimension (y direction) with the 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 in the pendulum. We obtained the numerical solutions of this system as well as the analysis for the different phase diagrams and the numerical solution for the intersection of the trajectory and surface, to begin with the study of chaos of this system.
Optimization of heat engines using different heat transfer laws by means of the method of saving functions
Authors: Barranco-Jiménez M A , Pacheco-Paez J C , Angulo-Brown F 
Published: March 2021

Abstract
In 2000 Velasco et al [1] introduced a new optimization criterion for the CA-engine model in terms of a profitable type process in the operation of a power plant model. This approach is based on using the so-called saving function as a measure of possible reduction of undesired side effects in heat engine operation. Velasco et al [1] defined two saving functions; one associated with fuel consumption and another associated with thermal pollution, where each saving function takes into account three weight coefficients that measure the participation degree of the corresponding process in the optimization criterion. We made use of this criterion to analyse the Novikov’s power engine model [2] but by using different heat transfer laws: Newtonian and Dulong-Petit (DP) heat transfer laws [3]. We compare our results with those reported by Velasco et al [1]. Our results show a saving in fuel consumption of approximately 44% and a reduction in thermal pollution of 42% with respect to the operating regime of maximum power, a value that is in agreement with some reported in the literature.
Numerical modeling of low strength reinforced concrete column strengthened with CFRP jacketing
Authors: Kurniawan P , Kasyanto H , Mauludin L M 
Published: March 2021

Abstract
Reinforced concrete column strengthened with Carbon Fiber Reinforced Polymer (CFRP) has been investigated numerically. Reinforced concrete column with low compression strength is used in this study. Concrete column is modeled by 3D solid elements with 8 nodes linear brick elements (C3D8R), whereas reinforcement bars modeled by 3D truss elements with 2 nodes first order elements (T3D2). In order to simulate concrete response in the specimen, concrete damage plasticity model with specifying damage parameters in both of compression and tension has been adopted in this paper. The specimen is subjected to uniaxial compression loading applied with displacement-controlled method. The effects of CFRP jacketing on reinforced concrete column with low compression strength are observed. The characteristic of reinforced concrete column combined with CFRP in terms of load-displacement behaviour and stress distributions are also evaluated. It is found that the numerical technique proposed in this study is quite efficient to predict the behaviour of low strength reinforced concrete column strengthened with CFRP with regard to the ultimate load, CFRP strain, and concrete strain distribution.
Students’ thinking process at the level of analysis in understanding square concept
Authors: Rizqika P , Sunardi  , Susanto  , Nuryami  , Shofyan A 
Published: March 2021

AbstractMathematics is important in all aspects of life. However, many students have problems understanding math problems, especially understanding the concept of geometry. Therefore, this study aims to describe the thinking process of students at the level of analysis in understanding the square concept. This research uses a qualitative approach. Data collection techniques were carried out by tests, interviews, and documentation. The research instrument used was the researcher, VHGT, test questions, and interview guidelines. The data source consisted of research subjects, namely two students of grade 8 with a level of analysis. The schematic of the square that S1 has built includes a square that has 4 sides and 4 angles. S1 undergoes an assimilation process when finding that a rectangle has 4 sides and 4 angles, where this property also belongs to square. S1 experiences a disequilibrium during the assimilation process when thinking that a rectangle is the same as a square visually. S1 experiences accommodation when it is found that squares and rectangles have different properties. S1 experiences a disequilibrium when understanding that the properties of a square and the properties of a rectangle are different. S2 experiences a disequilibrium during the assimilation process, which assumes that a rhombus is equal to a square. S2 experiences an accommodation process when understanding that a rhombus is not the same as a square. S2 experiences equilibrium when able to differentiate between a square and a rhombus.
The development of science, technology, engineering, art, and mathematics learning devices – lesson study for learning community to improve students’ creative thinking skill
Authors: Safik M , Hobri  , Yuianti N , Sarjono W , Sa’id I A 
Published: March 2021

Abstract
This research aimed to develop learning devices based on science, technology, engineering, art, and mathematics - lessons study for the learning community to improve students’ creative thinking skills on algebraic operation material. The learning devices developed were lesson plan, students’ workbook, and learning result test. The development model used Thiagarajan’s development model that consisted of four stages: define, design, develop, and disseminate. The subjects of this research were the eighth-grade students from (Islamic Junior High School) MTs. Nurul Islam Bades Pasirian. Students’ creative thinking abilities were measured using a creative thinking skill test. This research described the development process and validity, practicality, and effectiveness results. This research’s results were learning devices that met the criteria of validity, practicality, and effectiveness.
Development cognitive neuroscience based learning to use lesson study for learning community to increase mathematical literacy
Authors: Shodiq L J , Rokhmawati A 
Published: March 2021

Abstract
According to the results of observation with teachers it is known that students still considered topic of fractions were difficult. Students often made mistakes in changing and calculating the fraction of operation. One of the causes in their mathematics literacy was low. Mathematics learning commonly stimulated the work of the right brain and left brain only and ignoring anxiety of students when facing fraction of questions. However, the mathematics learning based on cognitive neuroscience is very needed. This research aims to produce learning model prototype in term of improving students’ mathematical literacy with the accompanying impact on the growth of communicative and collaborative skills. The developed model used is 4D (define, design, develop, and disseminate). Methods of data collection used observation, questionnaires, documentation techniques, and tests. The research was conducted in 3 cycles with lesson study for learning communities, each cycle went through 2 stages of a plan-do-see. The research subjects were 40 students in fifth grade of elementary school in the odd semester of 2020. The data were analyzed descriptive qualitatively through data reduction, data presentation, and conclusions. Based on data validation with learning technology experts, learning evaluation experts, and neurosains experts got a good value category, so that the learning model prototype was suitable to use in learning. The results of the pre-test post-test value of the learning implementation were analyzed using the paired sample T-Test obtained by t Stat = -2,87 < t Critical two-tail = 2,02 which was learning model prototype can improve students’ mathematical literacy. The Mathematical anxiety shown a decreasing, the communicative skill of students grew, the collaborative skill had not shown a significant increase. So it can be concluded that the learning model prototype is effective.
The effectiveness of chitosan from shrimp skin as a natural preservative for meatball
Authors: Gita R S D , Waluyo J , Dafik  , Indrawati  
Published: March 2021

Abstract
Meatball is one of the most favorite processed food in Indonesia it has delicious taste, tasty gravy, and affordable price. It is also easy to find a meatball stall in Indonesia, including Jember. Preservatives are usually used to maintain the condition of a meatball. Some preservatives, however, contain harmful substances, like formalin and borax. Both formalin and borax are not allowable for consumption since it may harm human’s health. The present study aimed to investigate a main ingredients for natural food preservative, to be further recommended as a preservative for meatball. The food preservative to be investigated in this study is chitosan made from shrimps shell wastes. To answer the research objective, a method used was an experiment of making chitosan solution. The concentration of chitosan created in the study is 1,5%. To test preservative efficacy of using chitosan, three treatments were given, (1) meatballs are coated with 1,5% of chitosan; (2) meatballs are mixed with 1,5% chitosan solution; and (3) meatballs without chitosan. These three treatments were observed and tested using organoleptic testing based on the length of storage, on day 1, 2, 3, and 4 in a room with a certain temperature. The parameters used for testing the preservatives included taste, color, odor, and texture. The study indicated that the 1,5% of chitosan solution was found effective for preserving meatballs naturally when used as coating.
The analysis of olympic tutors problem-solving skill of the national science olympic for elementary school level
Authors: Rufaida S , Nurdiyanti  
Published: March 2021

Abstract
This study aims to describe the olympic tutors problem-solving skill of the National Science Olympic for elementary school level and analyze based on the type of problem-solving skill. In a National Science Olympic competition, the selection is made based on the ability of students to solve questions, so that the teacher as olympic tutors need to apply correct problemsolving skills as the main key to solving olympic questions. This research was a qualitative descriptive study that aimed to determine the condition of an object through a case study for olympic tutors of the National Science Olympics for elementary school level in Barru Regency, South Sulawesi. The data collection methods were tests and interview. This study showed the olympic tutors problem-solving skill of the National Science Olympic for elementary school level in Barru Regency at the moderate category which revolved around the score 25 - 49. Based on the result of the analysis, in terms of the types and stages of problem-solving, most of the olympic tutors of the National Science Olympic for elementary school level did not understand systematic problem solving and still needed accuracy in choosing the most appropriate equations to use when solving problems.
Mathematical literacy of prospective mathematics teachers in solving social arithmetic problems in the context of the wetland environment
Authors: Zulkarnain I , Hidayanto T 
Published: March 2021

AbstractMathematical literacy is an individual’s ability to formulate, use, and interpret mathematics in various contexts. However, the achievement of Indonesian students’mathematical literacy is low, according to the PISA study. Therefore, it is necessary to have a mapping of the mathematical literacy abilities of mathematics education students who are prepared as prospective mathematics teachers. The research describes the mathematical literacy of prospective mathematics teachers in solving social arithmetic problems in the context of the wetland environment. This research used the descriptive method. The participants were 87 students in the second year of mathematics education study program at Universitas Lambung Mangkurat. The students were tested with social arithmetic problems in the context of the wetland environment. The results showed that there are five categorizations of mathematical literacy of prospective mathematics teachers in solving social arithmetic problems in the context of a wetland environment. These categories are 6% of subjects did not solve problems, 3% of subjects only identified problems, 60% of subjects solved problems but did not fit the given context, 3% of subjects solved problems, but the procedure or the final answer is wrong, and 28% of subjects can solve the problem correctly both in the procedure and in the final answer. Based on these findings, prospective mathematics teachers need to be prepared to be familiar with problems related to the context of their environment to improve their mathematical literacy skills.
Analyzing the online assessment using the expert system in fashion making practices of fashion design students in Universitas Negeri Malang
Authors: Irianti A H S , Sunandar A , Smaradigna A A , Aris A , Muhartiningsih R , Irzatul T 
Published: March 2021

Abstract
Online assessment using the expert system in fashion making practice was a new assessment as a result of developmental research. Online assessment using the expert system was made to avoid subjective assessment in evaluating the practice results. During the evaluation, there was a fitting process where students’ posture and face could give individual influences. The practice results from slim and pretty students would provide better effects than students who were fat and less beautiful, even using the practice assessment indicators. The physical appearance of the participants or models such as body shape, face, and others would psychologically affect the lecturers’ subjectivity during evaluation. Conducting practice evaluations using the expert system allowed students to report the practice results by answering online questions related to the fashion making results. Online assessment using the expert system facilitated the students to upload their practice results progress complete with answers following the issue in the online assessment software. Online evaluation with the expert system also assisted lecturers in monitoring the practice progress online that they could access everywhere and anywhere. This research aimed to analyze the online assessment of women fashion making practice using the expert system, to find the ease of use from the online system software, assessment content suitability, and assessment objectivity. For the methodology, this research used a quantitative descriptive method in a population of 28 Fashion Education students’ class of 2018. The sampling technique in this research was total sampling. This research used the close questionnaire as the research instrument and analyzed the data using the percentage technique. The results showed that first, software easiness such as followings instruction, operational, filling and uploading the progress, indicated that 25 of 28 respondents, or 89.28%, were in favour of the ‘easy’ category. Second, assessment content analysis, such as assessment indicator, content from each index, and assessment aspect, demonstrated that 26 of 28 respondents or 92.85% was in favour of the ‘relevant’ category. And third, the assessment objectivity such as definite measuring instruments and objective assessment presented 27 of 28 respondents in support of the ‘objective’ category. The conclusion of this research using the expert system was overall in the excellent grade. This report was accurate because, in direct practicum assessment, the fitting session used model, and thus the physical condition of the models who were pretty and slim often gave subjective final results.