bluuebunny/crossref_metadata_2025 huggingface dataset:
Determination of the tourist route in Malang Raya by using ant colony optimization
Authors: Rozidi A , Anam S , Habibah U
Published: May 2021

Malang Raya is one of the most popular tourist destinations in Indonesia and has many interesting tourist attractions. Tourists need much time to visit all the tourist attractions. It is not possible to visit all the tourist attractions since vacation time is limited. Therefore, the method for determining the tourist route with the minimum time and satisfy the constraint is needed. The problem is Vehicle Routing Problem (VRP) and can be solved by meta-heuristic. There are several meta-heuristics that can be used to solve VRP, for example Genetic Algorithm (GA), Particle Swarm Optimization (PSO), and Ant Colony Optimization (ACO). ACO has the advantage of a good positive feedback mechanism when compared to GA and PSO. For this reasons, this paper presents the determination of tourist route in Malang Raya by using ACO. However, ACO tends to solution stagnation. In this paper, the solution stagnation of ACO will be solved by applying the dual pheromone tables. The results show that ACO with dual pheromone tables can solve the problem of determining tourist routes in Malang Raya well in terms of quality of solution because ACO with dual pheromone tables can obtain better results in the time cost of the route than standard ACO.
Construction of multiplicative groups in modular arithmetic
Authors: Purwanto
Published: May 2021

There are multiplicative groups in modular arithmetic. It is known that when n is a positive integer, the set of all positive integers less than and relative prime to n is a group under multiplication modulo n. Some authors have studied multiplicative groups in modular arithmetic, and many of these groups have been constructed. In this paper we review some of the constructions, including constructions using elements of a geometric sequence and elements of an arithmetic sequence. Some of the constructions are extensions of the existing groups, and some others are new constructions. We also show that it is possible to find other new constructions.
Automorphism of complete 2,3,4- ary trees
Authors: Rahmadani D , Sulandra I M , Damiatun
Published: May 2021

Let G be a simple graph with vertex set V(G) and edge set E(G). Automorphism of G is an isomorphism from G to itself. In other words, an automorphism of G is a permutation φ of V(G), which has the property that uv ∈ E(G) if and only if φ(u)φ(v) ∈ E(G), for every u, v ∈ V(G) that is φ preserves adjacency. The complete n-ary tree is a rooted-tree where its every internal vertex has exactly n children. The height of a rooted tree is the number of edges on longest path connecting the root to a leaf (a vertex of degree one). In this paper, we determine the number of automorphism of complete 2,3,4-ary trees with height h, for any positive integer h. We also conjecture the general formula to determine the number of automorphism of complete n-ary trees, for any n ≥ 5.
On square roots of matrices over the max-time semiring ℝ+
Authors: Sulandra I M , Isnia A N
Published: May 2021

The set of all nonnegative real numbers ℝ+ with respect to two operations ⊕ : (a, b) → max{a, b} and ⊙ : (a, b) → ab forms a semiring that is called a max-times semiring. A square matrix A over the semiring has a max-times square root if there is a matrix B over the semiring such that B ⊙ B = A. Whereas, a square matrix A over the semiring ℝ+ with respect to the tow usualy addition and multipliacation operation has a conventional square root if there is a matrix B over the semiring such that B × B = A. We begin this study by giving an example of an 3×3 upper triangular matrix over ℝ+ that has both conventional and max-times square roots. In this paper, we do research on necessary and sufficient conditions of matrix having max-times square roots and compare it to the conventional one. Furthermore, we determine necessary and sufficient conditions of such matrix having either one, both, or neither one. Finally, we investigate the numbers of square roots, if any, in each case under all conditions.
Spatial spillover model: a moment method approach
Authors: Atikah N , Rahardjo S
Published: May 2021

. The spatial effect can be in the form of a global overflow over time, which is called a spatial spillover. Spillover occurs when changes in one area cause changes in another. Spatial Durbin Model (SDM) is the development of the spatial autoregressive model (SAR), where the dependent variable and the independent variable both contain spatial effects. In this study, we will determine the estimation of the Spatial Durbin Model (SDM) parameters using the Method of Moment (MM). The results show that the parameter estimation using the Method of Moment in the Spatial Durbin Model (SDM) is unbiased and consistent.
Stability analysis of SIRS epidemic model on measles disease spreading with vaccination and migration
Authors: Kusmawati I S , Chandra T D
Published: May 2021

Measles or also called Rubeola 9 days measles is an infectious disease caused by the Paramyxovirus virus and is transmitted through coughing and sneezing characterized by fever, cough, runny nose, and reddish rashes on the skin. Measles is included in the endemic category in developing countries, one of which is Indonesia. In this paper, we analyze the stability of the SIRS epidemic model with vaccination and migration and simulate the model based on data obtained from the Indonesian Ministry of Health in 2015 and migration data from the SUPAS (Survei Penduduk Antar Sensus) in 2015. Based on the results of the analysis that has been done, we obtained two equilibrium points, namely disease-free equilibrium point and endemic equilibrium point. If the value of R
0 <1, then the disease-free equilibrium point is said to be locally asymptotically stable, and if the value of R
0 > 1, then the endemic equilibrium point is locally asymptotically stable. In the case of the spread of measles based on data in East Java Province in 2015, a basic reproduction number is obtained R
0 = 4,48609.10−5 <1 which means that measles is no longer epidemic in a certain time provided that vaccination must be carried out continously and evenly.
Dynamical Analysis Predator-Prey Population with Holling Type II Functional Response
Authors: Pusawidjayanti K , Asmianto  , Kusumasari V
Published: May 2021

In this article, we investigate the dynamical analysis of predator prey model. Interaction among preys and predators use Holling type II functional response, and assuming prey refuge as well as harvesting in both populations. This study aims to study the predator prey model and to determine the effect of overharvesting which consequently will affect the ecosystem. In the model found three equilibrium points, i.e., E
1(0,0) is the extinction of predator and prey equilibrium, E
2(x
2, 0) is the equilibrium with predatory populations extinct and the last equilibrium points E
3 (x
3, y
3) is the coexist equilibrium. All equilibrium points are asymptotically stable (locally) under certain conditions. These analytical findings were confirmed by several numerical simulations.
Kinetic energy of M2 tide in the Makassar Strait
Authors: Pelawi E S B S , Ikhwan M , Haditiar Y , Wafdan R , Muhammad M , Rizal S
Published: May 2021

The Makassar Strait (MS) is the main passage through the Pacific to Indonesian waters, which divides the islands of Kalimantan and Sulawesi. These waters are rich with natural resources. The research objective was to determine the energy produced by the M2 tides in the Makassar Strait. Ocean currents and energy are analyzed from the output of a two-dimensional numerical model. The results showed that the tidal flow velocity in the Makassar Strait was above 1 m/s, especially in Balikpapan (1.1975 m/s,) Mamuju (1.3379 m/s), and Pantoloan/Palu (1.2728 m/s). While the power or tidal current energy in Balikpapan is 3, 6238 × 104 kWatt, Mamuju is 2, 0215 × 105 kWatt, and Pantoloan/Palu is 7, 4006 × 105 kWatt. The tidal energy is intense in Pantoloan/Palu compared to other stations.
Facies probability application for gas reservoir characterization
Authors: Arifiani P A A , Haris A
Published: May 2021

Reservoir characterization through seismic inversion is the principle method in hydrocarbon exploration. Facies probability is an advance method of reservoir characterization which integrates model-based seismic inversion and facies classification to construct a better reservoir modelling. The reservoir modelling is produced from four main steps. First is crossplot analysis to define the relation between acoustic parameter and petrophysics parameter. Second, model-based seismic inversion to produce acoustic impedance volume from seismic data. Third, facies classification which is defined from porosity effective, shale volume and water saturation. Final step is Bayesian Inference Framework to model probability density function (pdf) of each facies. The result of crossplot analysis shows that there is a linear relationship between acoustic impedance and porosity hence the porosity volume can be derived from the model-based inversion result. Facies classification is divided into two categorical zone, pay and non-pay. Pay zone is categorized as a high porosity layer filled with gas. Its parameters fit with Vshale > 0.6, Sw < 0.7 and porosity effective > 0.22. Then estimation is run using Bayesian probability into acoustic impedance volume and porosity volume resulting probability volume of each facies.
Effect of BaCO3 addition on critical temperature of Bi-Pb-Sr-Ca-Cu-O superconductor
Authors: Akbar I A , Imaduddin A , Humaidi S , Nugraha H
Published: May 2021

Bi-Pb-Sr-Ca-Cu-O high temperature superconductor has been applied in the field of electricity as power transport cables. This work has been carried out to investigate the effect of addition of BaCO3 on Bi1, 6Pb0, 4Sr2Ca2Cu2O10 superconductors. Solid state reaction method was used to prepare all samples. The starting materials were Bi2O3, PbO2, SrCO3, CaCO3, CuO, and BaCO3 powder. Starting materials without BaCO3 were ground using a mortar agate for 3 h. After calcination process of 820°C for 20 h, samples were mixed with BaCO3 (1 %wt, 2 %wt) and then sintered by 850°C for 30 h. Characterizations ware conducted by using cryogenic magnet to determine the critical temperature (Tc), SEM-EDX to analyze morphology, and XRD to determine the phase formed. There were semiconductor properties at high temperature and it was found that the addition of BaCO3 decreased Tc of the samples. 1 %wt BaCO3 showed a critical temperature with Tconset = 86 K and Tczero = 52 K, and 2 %wt of BaCO3 has Tconset of 80 K, and Tczero of 23 K. The surface morphology contains agglomeration and there is a lot of porosity. The dominant phase formed is Bi(Pb)-2212 with a volume fraction of 64.71%.
Forecasting sea surface temperature anomalies using the SARIMA ARCH/GARCH model
Authors: Oktaviani F , Miftahuddin  , Setiawan I
Published: May 2021

The areas that are close to the Indian Ocean can give a significant impact on climate change that caused by SSTA. Based on the records from NOAA website, there are data about points in the Indian Ocean. Moreover, climate change on earth is influenced by several parameters, one of them is called SSTA. Therefore, it is necessary to forecast SSTA in the future to minimize the impact of climate change. With a purpose to predict data that contains seasonal patterns, the method that can be used is SARIMA method with ARCH or GARCH. This study aims to determine the results of SSTA forecasting for the period from August to December 2018. This study uses the 4°N90°E point, which is a point located close to Aceh Province. The data used are daily data obtained from the NOAA website, from July 2010 to July 2018. Based on the research results, the best model for SSTA forecasting is the SARIMA model (2, 1, 1)(0, 1, 1)-GARCH(1, 1) with forecasting accuracy values of 3.67% MAPE, 0.032 MAE, and 0.016 RMSE. The MAPE values that are smaller than 10% indicate that the SARIMA (2, 1, 1)(0, 1, 1)-GARCH(1, 1) model is very good for forecasting SSTA in the future.
High school Physics teachers’ perceptions of the learning revolution era 4.0 at training activities in Bener Meriah Regency
Authors: Elisa E , Farhan A , Herliana F , Wahyuni A , Susanna S
Published: May 2021

The constraints of the limited practicum facilities for Physics lessons in Bener Meriah Regency High School schools can be overcome by virtual laboratory practicum. Learning technology using a virtual laboratory experiment method based on Smart Phone is given to Physics teachers in the district so that they can use simple information technology applications in learning. The subject matter of physics used in this training was Waves and Optics. This activity is gradually carried out to pioneer the realization of physics learning in high schools following the demands of the industrial era 4.0. The output is expected to improve the pedagogical quality of teachers, the learning process, and to overcome the limitations of Physics practicum tools, and to support online learning during the Covid-19 pandemic. The activity was attended by 10 high school teachers in Bener Meriah Regency. All participants were able to master the transfer of technology provided. They are optimistic that this IT technology can be implemented in the learning of Wave and Optical material Physics in their schools on duty. 100% of trainees are satisfied with the service and expect will be any similar activities to be continued for other Physics materials.
Computing the auto regressive distributed lag (ARDL) method in forecasting COVID-19 data: A case study of NTB Province until the end of 2020
Authors: Negara H R P , Syaharuddin  , Kusuma J W , Saddam  , Apriansyah D , Hamidah  , Tamur Maximus
Published: May 2021

The purpose of this research is to conduct data forecasting on the spread of COVID-19 in West Nusa Tenggara Province, Indonesia at the end of 2020. The data used in this research is the COVID-19 data in NTB Province including the data of the number of positive patient, the number of patients recovered and the number of patient passed away. The forecasting process uses the Autoregressive Distributed Lag (ARDL) method of the GUI Multiple Forecasting System (G-MFS) based on MATLAB by determining the prediction on the next day of the graph equation generated after the data simulation. The forecasting of the COVID-19 spread in NTB at the end of the year of 2020 obtained that the number of confirmed patients amounting to 19, 614 people with an average increase of 1.48%, the number of patients healed are 6, 651 with an average increase of 1.10%, and the number of patients died amounting to 4, 953 people with an average increase of 2.42%. The average increase in the number of patients who died showed that the provincial government of NTB needs to give more serious attention to handling COVID-19 patients.
Efforts to improve students’ mathematical critical thinking ability by using Team Assisted Individualization learning model
Authors: Marasabessy R , Hasanah A , Angkotasan N
Published: May 2021

The development of critical thinking is the goal of the Indonesian education curriculum. However, research on how to develop and improve these abilities is still rarely studied. In this article, we offer a team assisted individualization-learning model in improving critical thinking skills. The objectives of this study were (1) to describe the improvement of students’ mathematical-critical thinking skills using the Team Assisted Individualization learning model, (2) To determine the increase in students’ critical thinking skills after team assisted individualization learning has carried out. This study used experimental research. The subjects in this study were fourth-semester students of the Khairun University mathematics education program. The instrument used was a question describing students’ mathematical-critical thinking skills. Data have been analyzed per indicator and as a whole using descriptive analysis, namely benchmark reference guidelines (PAP) scale five and Normalized Gein. Data were analyzed using the inferential analysis to determine the increase in students’ mathematical critical thinking skills, namely hypothesis testing (one-sample t-test). The result of the data analysis showed an increase in students’ mathematical critical thinking skills, which were interpreted moderately after implementing the assisted individualization team learning model.
The impact of students’ personality types on the application of problem-solving strategies in solving PISA questions
Authors: Mawaddah A , Anwar  , Yusrizal  , Zubainur C M
Published: May 2021

The problem-solving strategy is one of reasons why Indonesian students competing in PISA only placed at the lowest rank. This is caused by some factors, including personality types. To indicate the effect of these types towards students’ strategies used is required more detail explanation. This research aims at investigating the strategies used by students in solving PISA questions based on personality types. There were 30 junior high school students in Banda Aceh involved in this research. Two research instruments were used, one consists of level 4, 5, and 6 PISA questions and another one is the Myers-Briggs Type Indicator questioner. The data gathered were analysed by grouping students based on the Myers-Briggs types. Afterwards, students’ answers to PISA questions were matched with the ten indicators of Posamentier and Krulik’s problem-solving. The result of this research shows that students come under 6 of 16 personality types. The result indicated that personality types impact the strategies which students applied in solving a problem in answering PISA questions. The implication of this study shows that teachers require to use combination of problem solving strategies to address different types of students’ personalities in Mathematics teaching and learning processes in order to optimize students’ achievements, particularly in problem-solving.
Mathematical communication skills in solving block and cube problems
Authors: Zulhelmi  , Anwar
Published: May 2021

Mathematical communication skills are required for understanding the lessons given by teachers. Students’ low mathematical communication skills are due to their lacking participation in learning or they are rarely allowed to ask or express their opinions. Learning process is still only the teachers teaching in front of the classroom and assigning tasks to students resulting in mathematical communication skills have not been able to be conveyed properly. This research aims to describe students’ written mathematical communication skills in solving cuboid and cube problems and to find out factors that influence mathematical communication skills. The research was descriptive means it explained and described students’ mathematical communication skills based on their indicators. The methods used were tests and non-test to see the students’ ability and to observe how students expressed opinions based on the answers they have written. The results showed that the problems faced by moderate and low ability students related to aspects of writing and drawing and the difficulty of expressing mathematical ideas. Highly qualified students had fulfilled all aspects of mathematical communication skills, namely writing, drawing, and mathematical expression in presenting mathematical ideas in solving math problems.
Guiding children in learning subtraction by using contextual strategy: as an attempt to develop students’ number sense
Authors: Novita R , Herman T
Published: May 2021

Subtraction operations are basic number operations that have been introduced to students at the 2nd grade of elementary school. Several studies have shown that this topic is difficult for students to understand and causes many problems in learning of numbers. Students’ constraints in performing this subtraction operation usually occur when subtracting two numbers in tens, hundreds, or more or numbers containing 0. One of the procedures that teachers often teach students in solving the problem of subtracting two numbers is borrowing techniques. This technique is often seen as forced and very abstract to students. This study aims to describe how students thinking in performing subtraction on numbers through more contextual strategies that they understand. This study used a single-subject research design with multiple baselines across individuals (n = 2) to evaluate the effectiveness of the measures performed. The intervention observed in this study was to use the number of subtraction technique with a different contextual strategy between the two subjects. The results indicate that the two contextual strategies used show a positive effect on understanding the number subtraction operation. The results also showed that subtraction without borrowing (not using formulas) made students more creative in solving the subtraction problem.
Development of student worksheets on ethnomathematics-based trigonometry through Project-Based Learning models
Authors: Husna N , Saminan  , Abidin Z
Published: May 2021

One of Indonesia Curriculum 2013 learning principles is learning that prioritizes culture and the empowerment of students. The culture of certain societies contains a mathematical concept known as ethnomathematics. One of the many mathematical materials found in ethnomathematics is trigonometry. However, in reality, students have difficulty mastery of trigonometry material. So far, ethnomathematics-based learning tools in Aceh traditional houses as an application of trigonometry are not yet available. Therefore, it is necessary to develop ethnomathematics-based learning tools. This study aims to develop an ethnomathematics-based trigonometry project worksheet through the Project-Based Learning model that met the valid criteria. This research refers to the Plomp development model, which consists of preliminary research and a prototyping stage. This study’s instruments were needs analysis sheets, validation sheets, observation sheets, and response questionnaires. The results showed that the developed Project Worksheet met the valid criteria because all validators stated that the project worksheet was fit for use.
Students’ mathematics problem solving ability through Model Eliciting Activities (MEAs)
Authors: Wahyuni S , Dahlan JA , Juandi D
Published: May 2021

Mathematical problem solving is an ability that is needed in the real world, especially in the field of work. Therefore, it is necessary to hone these skills from an early age. This study aims to describe the mathematical problem-solving abilities of students who learn to use MEAs. This research was conducted in class VIII at a junior high school in Bandung, Indonesia. The research method used is a qualitative approach. The instrument used was a test of mathematical problems solving and interviews. The results showed that the description of the mathematical problem-solving abilities of students who learned using MEAs, namely low category students succeeded in getting to the simple problem-solving planning stage so that the solving steps were not correct. Students in the category of being successful in problem planning but mistakenly seeing the facts in the problem, so that mistakenly made the first stage mathematical model so that students were wrong in determining the final goal of the solution. High category students succeed at the completion plan implementation stage of making the first stage mathematical model but mistakenly consider the real-world situation after the mathematical model at a later stage.
The effectiveness of the Project-Based Learning (PjBL) model in students’ mathematical ability: A systematic literature review
Authors: Yunita Y , Juandi D , Kusumah Y S , Suhendra S
Published: May 2021

One of the learning models recommended in the 2013 Curriculum is Project Based-Learning (PjBL) model with the demands for the skills required in the 21st century. This learning model can be applied to enhance students’ mathematical ability. This study aims to determine and evaluate the effectiveness of the PjBL model process to foster mathematical ability. This study used a systematic literature review method, including planning, implementing, and reporting. The data were analyzed based on data inclusion criteria, and then the data were extracted, resulting in 26 studies. The findings indicated that an increase in mathematics abilities through mathematics learning using PjBL could occur if students are directly involved in the learning process with clear directions, and they pay attention to essential aspects, such as learning activities, optimal use of time, and mathematical ability. Another finding revealed that the large percentage of the number of studies discuss the influence of the PjBL model on problem-solving and creative thinking skills. There is also an increase in publications, especially those indexed by Scopus every five periods and many studies using random research sampling. Thus, the PjBL model is appropriate for achieving learning objectives, especially in mathematical ability.
Students’ thinking process in solving Higher-Order Thinking (HOT) problems through Aptitude Treatment Interaction (ATI) learning model
Authors: Hanum O , Johar R , Yusrizal
Published: May 2021

The assessment model in the 2013 Curriculum has adapted the international standardized assessment model. It is expected to help students to improve their higher-order thinking skills. One of the differences among students that teachers should pay attention to is their thinking process when solving math problems. The Aptitude Treatment Interaction (ATI) learning model is a learning model that adapts learning to the characteristics of students’ abilities. The purpose of this study was to investigate how high-, moderate-, and low-ability students could solve higher-order thinking (HOT) problems through the ATI learning model. This research employed mixed methods. The participants were students of Junior High School 3 Banda Aceh, in which three of them were interviewed. The data were obtained from observations, tests, and interviews. The results showed that the ATI learning model did not directly impact the students’ thinking process in solving HOT problems. Instead, it had a profound effect on students’ activities during the study. The high-ability students were better than the moderate- and low-ability students in each indicator of the thinking process in solving HOT questions. Students’ activities increased during the learning process from the first meeting to the last one.
Didactical design of vectors in mathematics to develop creative thinking ability and self-confidence of Year 10 students
Authors: Adharini D , Herman T
Published: May 2021

This research was motivated by the low ability of creative thinking in mathematics and students’ self-confidence. This study aims to compile a didactic vector mathematical design to develop students’ creative thinking skills and self-confidence. This type of research is Didactic Design Research (DDR). The participants were 50 Year 12 students and 24 Year 10 science students. Data collection on learning obstacle was carried out on Year 12 students using tests, interviews, and textbook analysis. It was found that most students had didactical obstacles. Students had low creative thinking ability, and students with mathematical skills low had low self-confidence. The didactic design was implemented online twice for Year 10 students using the zoom meeting application and google classroom. Students’ creative thinking skills develop well for questioning and guessing and product improvement. Most of the students’ self-confidence is in good condition. Further research should provide an explanation of the related material before the test, make a didactic design using e-learning, add formulas for student activities, and provide examples and explanations for each completion step.
The Development of a rapid method for Plutonium separation by extraction chromatography and its application for environmental samples
Authors: Khairina R , Giyatmi  , Makmur M , Kusdiana
Published: May 2021

This research aims to develop a rapid method of plutonium analysis from sediment samples using the extraction chromatography method with TRU resin. This approach will be compared with the anion exchange method with DOWEX resin previously conducted in the BATAN radioecology laboratory. Plutonium measurements was carried out using an alpha spectrometer with a PIPS detector after the separation processes. The results showed that recovery using extraction chromatography followed by the microprecipitation method resulted in an average recovery of 71.22 percent, compared to anion exchange using the electrodeposition method, which obtained about 58.89 percent. Since a combination of chromatographic extraction with electro-deposition, the recovery is still low, about 27.56 percent. The chromatographic extraction method with microprecipitation method to sediment samples from the coast of Merak resulted in an average activity of 0.14 Bq/kg dry. The activities obtained are comparable with the previous data from the Merak coastal sediment study. The advantages of using the extraction chromatography method compare to using the anion exchange method to separate plutonium from sediment samples are the shorter separation time and the less acid waste produced. Another advantage is that it is more selective to separate plutonium from other actinides. This approach is very suitable for emergency preparedness when there is an emergency response.
Magnetic Sulfonated Chitosan composite beads for Mercury removal from Aqueous solutions
Authors: Lelifajri  , Rahmi  , Ayu A S W
Published: May 2021

Magnetic sulfonated chitosan composite beads had been prepared and applied for mercury removal from aqueous solutions. Preparation of magnetic sulfonated chitosan composite beads was initially performed by the sulfonation of chitosan and continued with the addition of iron oxide particles prepared from local iron sand to form composite beads. The magnetic sulfonated chitosan beads were characterized by FTIR and XRD analysis. FTIR spectra confirmed the formation of magnetic sulfonated chitosan beads. The patterns of XRD exhibited the decrease of chitosan crystallinity after modification. The result of adsorption experiments showed that the addition of sulfonation and iron oxide particles can improve the adsorption capacity of chitosan.
Phytochemical screening and spectrum profile of functional group from Banana (Musa paradisiaca L.) stem waste extract using Fourier-transform Infrared (FTIR) Spectroscopy method
Authors: Purnama R C , Primadiamanti A
Published: May 2021

Banana (Musa paradisiaca L.) is plant that contain secondary metabolites compounds such as tannins and flavanoids. Tannins and flavanoids have various properties for human health. Research had been conducted to identify secondary metabolite compounds (tannins, flavanoids, and saponins) with phytochemical screening methods and to look at the spectrum profile of the functional group found in the waste extract of banana stem. The waste of banana stem extracted with 96% ethanol. From the obtained extract, evaporation and phytochemical screening were carried; consecutively. From the screening results, tannin compounds were characterized by a greenish-black result, and flavanoids created a deep red color. Saponins were expressed negatively because the formed foam had a height of 0.3 cm and did not meet the requirements of saponins expression (foam height 1-3 cm and stable for 5 minutes). After that, the identification of the functional group found in the banana stem waste extract was carried out using Fourier-transform Infrared (FTIR) spectroscopy. Banana stem waste obtained the form of compound function clusters supported by o-H bound absorption data in the area of 3284.91 cm-1, c = O in the area of 1643.06 cm-1, bend CH2 in the area 1409.25 cm-1, and C-C in the area 1078.56 cm-1.
Scale-up preparation and testing of activated-carbon-cloth as carbon-filter prototypes for ammonia-vapor adsorption
Authors: Adlim M , Rahmayani R F I , Zarlaida F , Yudha M B
Published: May 2021

This study is a scaled-up experiment for carbon cloth made of the pristine-palm-kernel shell studied previously at the laboratory level. Prototypes of activated carbon filter (cylindric net, 40 cm height & 18 cm diameter) were prepared from the activated palm-kernel carbon cloth. The ammoniac adsorption capacity test was carried out within six closed rooms with the individual dimension of 120 cm × 90 cm × 220 cm. The ammonia vapor samples were determined by UV-Vis spectrophotometric method. Each room contained 2.8 × 10−5 M of ammonia vapor at ambient temperature, (28 + 1)°C atmospheric pressure. The activated carbon mean-weight of (179 + 5) g or equivalent to (0.1 + 0.003) g per cm2. The optimum time of adsorption was 60 minutes and the mean adsorption capacity of the carbon filter was 1.78 × 10−5 M per 1720 cm2 of carbon cloth. The carbon filter prototype absorbed 60.6% of ammonia vapor in the closed room. The adsorption remained constant, although the absorbent and time were expanded.
Synthesis of iron-doped zinc oxide (Fe-ZnO) nanoparticles by using several stabilizers
Authors: Muktaridha O , Adlim M , Suhendrayatna S , Ismail I
Published: May 2021

Studies on the effect of the stabilizer of chitosan, citric acid and urea for preparation Fe-doped ZnO have been conducted. Both ZnO and Fe were prepared from each salt precursor solution. The Zn2+ was added fist and subsequently Fe2+ by dropwise method into each stabilizer solution before converted into the hydroxide compounds before annealing. All metal ion solutions precipitated out after 7 minutes of NaOH addition except in urea stabilizer, where the solution remained in the colloidal form for more than 30 minutes. The hydroxyl ions are required for ZnO formation, but it weakens chitosan and citric acid stabilizing capacity, which instigated ZnO particles to be highly agglomerated. Each stabilizer generated a smaller ZnO crystallite size compared to the control sample. Fe-ZnO crystallite size prepared using chitosan, citric acid and urea as the stabilizer was 14.75, 23.29 and 22.51 nm, respectively. The crystallite size of Fe-ZnO that was prepared without stabilizer (control) was 32.89 nm.
The utilization of vehicle waste-oil as a material source for preparing carbon dots
Authors: Hasrudin A , Abidin Z , Hiedayati N , Kharisma D
Published: May 2021

Synthesis of carbon dots (c-dots) from vechile waste-oil is one of the alternatives for reducing the burden of environmental pollution. This study aimed to develop a green and economical strategy to produce C-dots by using motor oil waste. C-dots were synthesized by heating motor oil waste in the various percentage of sulfuric acid solution (95, 70, 30, and 0% H2SO4). The synthesized C-dot was characterized by UV-Vis spectrophotometry and Fourier Transform Infrared (FT-IR) spectroscopy. The result showed that the carbon dot produces blue color at 365 nm of UV light. This color was attributed to the oxidation of chemical content in motor oil waste. Therefore, four peaks were obtained at 203 nm, 204 nm, 215 nm, and 210 nm for all samples. Based on FT-IR spectra, the most prominent sample difference was observed at peak 1630 cm−1. The characteristic band of the carbonyl group was identified at the c-dot concentration (70 and 95%) but was not observed in the c-dot concentration (0 and 30%). The presence of carbonyl groups caused the fluorescent color to gradually shift from dark blue to light blue.
Determination of the Aflatoxin levels in Corn (Zea mays, L.) during storage process
Authors: Mulyati A H , Sutanto  , Warnasih S , Herlina E
Published: May 2021

Aflatoxin contaminant in corn being a serious problem, due to its toxicity. This contamination was influenced by the storage and treatment process. During storage, the aflatoxin level was influenced by the water content of corn seed. In this study, the water content were performed by gravimetric method, while the aflatoxin contents have been carried out by ELISA and HPLC methods. The corn seed samples were obtained from Tangerang, Cikande, and Cirebon. The results showed that the aflatoxin content were increased in fourth-week storage. The analysis of the aflatoxin content using the ELISA method showed that corn seed obtained from Tangerang, Cikande, and Cirebon were 74, 06 ppb; 9.33 ppb; 28.67 ppb respectively, while the HPLC method showed that the aflatoxin content were 75.02 ppb; 9.83 ppb; 28.43ppb respectively. The results also showed that the water content in the corn seed obtained from Tangerang, Cikande, and Cirebon were 10.64%; 10.17%, 10.25% respectively on fourth-week storage. In conclusion, the aflatoxin content in corn seed from Cikande and Cirebon were in accordance with SNI standards, while corn seed from Tangerang contain aflatoxin was above 50 ppb.
Effect of serving temperature on the nutritional quality of cereal foods
Authors: Warnasih S , Mulyati A H , Sutanto S , Herlina E
Published: May 2021

Cereal is one of the oat-based food products that contain high dietary fibre and nutritional value. One of the factors that affect the nutritional quality of the cereal during serving is the temperature of the water used for brewing. This study was carried out to evaluate the effect of serving temperature on the nutritional value of ready-to-eat cereal foods. The sample consisted of 4 types, i.e instant oat (A and B), and quick cook oat (A and B). Each sample was brewed using four different water temperatures, namely 40, 60, 80, and 100 °C. Then the nutritional content analyses were carried out included protein, fat, dietary fibre, and magnesium, also the organoleptic test with the panellist. The results showed that the treatment of the four serving temperatures resulted in levels of protein, fat, fibre, and magnesium which were significantly different, while the serving water temperature of 100 °C resulted in higher levels of dietary fibre. The sample that was most preferred by the panellists was the sample that was brewed with water with a temperature of 60 °C, while the sample that was least preferred was the sample that was brewed with water at 40 °C, both in the instant oat and quick cook oat samples. Therefore, water with a temperature of 60 °C was recommended for serving cereals.
Application of simple kinematic model from flexion movement of upper-limb with RGB-D camera perspective
Authors: Barri M H
Published: May 2021

This study describes the use of an RGB-D camera for the assessment of the upper-limb movement for stroke rehabilitation patients. The assessment process is carried out by making comparisons between patient movements and simulated movements. The motion simulation is modelled by the kinematics model of the 6 DoF arm with extended flexion motion. Tests were carried out on 13 normal patients with movement schemes that often appear in the rehabilitation process. The results show that the use of the 6 DoF model results in better accuracy and calculation time than using the 8 DoF model.
Beams destruction by explosion of non-contact charges of condensed explosives in water
Authors: Volodin G T , Kochergin D S
Published: May 2021

The analysis of effects of the hydrodynamic field created by the explosion of condensed explosive charge on the simplest construction element in the form of beams in the water is performed. The features of the load due to the location of the beam in the water are taken into account by the attached mass introduction. The classical condition of the element destruction is used, according to which it is necessary that the stress in the element is greater than the ultimate resistance of the material and refined of O.E. Vlasov’s formula on the proportionality of the bending moment to the acting explosive load pulse is used.
Torsional waveguide modeling of an ultrasonic medical instrument
Authors: Gouskov Alexander Mikhailovich , Grigoryev Yuri Vsevolodovich , Pyae Phyo Aung
Published: May 2021

Based on analytical solutions for several torsion waveguides, transition matrices are derived, which are then used to calculate torsional vibrations using initial parameters. The paper contains a comparative analysis of different types of concentrators. As the waveguide’s design scheme, a rectilinear rod of the variable cross-section with various fastening types is adopted. The method of numerical determination of natural frequencies and waveforms of the waveguide of an ultrasound medical instrument (UMI) is presented. For a given waveguide layout, the amplitude angles of rotation and torques in the UMI are calculated at a specific frequency of oscillation excitation. A satisfactory agreement of the obtained results is demonstrated.
The analysis of the laminar-turbulent transition onset for the Couette flow in the flat channel with the velocity profile periodic background perturbation
Authors: Kolodezhnov V N
Published: May 2021

To predict the laminar-turbulent transition, we adopted an approach, which is based on the transverse viscosity factor threshold addition hypothesis. Taking into account the conditions imposed on the corresponding dimensionless complexes within the framework of this approach, we analysed the transition onset for the Couette flow in the flat channel with consideration of the velocity field perturbation initial periodic background. The critical value for the Reynolds number was obtained, which is in satisfactory agreement with the known experimental data.
Point-like mechanical singularity in the method of boundary states
Authors: Polikarpov M V , Penkov V B , Levina L V
Published: May 2021

This paper presents an effective technique for solving some spatial problems in the theory of elasticity, particularly for a bounded set of point-like physical singularities. This technique development involves the advanced energy method of boundary states (MBS) for a class of solutions with singularities. A test problem for a single singularity such as the center of expansion complying with the proposed technique calculations reliability has been solved and analyzed. The use of the method of boundary states demonstrates the efficiency of the technique in solving problems with many centers of expansion and concentrated forces in an unbounded medium. The results of problem solving are displayed in a convenient graphical form.
Passive transport safety based on the calculation of the temperature regimes of brake units taking into account their heat dissipation and thermal resistance to heat dissipation
Authors: Belokurov V P , Belokurov S V , Shtepa A A , Korablev R A , Busarin E N
Published: May 2021

The article discusses the conditions for increasing the passive safety of vehicles due to the use of the results of calculating the temperature regime in frictional friction pairs in the design of brake assemblies, both taking into account their active heat dissipation, and taking into account the contact thermal resistances along the path of the dissipated heat flows. This temperature calculation allows, at the design stage of new brake units, to determine their optimal geometric arrangement, taking into account the increased thermal dynamics of friction of friction pairs during their active heat dissipation. In addition, it becomes possible to recommend the optimal frictional pairs of friction in the brake units, taking into account their thermal stability. The use of the above thermal calculations will ensure an increase in the performance of the brake units, which, ultimately, will provide an increase in the passive safety of vehicles.
Development of a stimulating mechanism for the coordinated management of agents’ resources in the implementations of joint projects
Authors: Bondarenko Yu V , Azeez A E , Azarnova T V , Barkalov S A
Published: May 2021

This article is devoted to the development of a mechanism that makes it possible to increase the efficiency of agent resource management by forming an optimal package of projects and a coordinated distribution of profits from its implementation. A feature of the proposed mechanism is its focus on stimulating agents to be active at the stages of initialization and implementation of merger projects. The proposed approach is based on mathematical models and methods. At the first stage of the mechanism, it is proposed to find the optimal package of projects on the basis of a discrete optimization model. To implement the second stage, associated with the distribution of the obtained profit, the concept of an agreed profit distribution is introduced and its connection with the solution of a cooperative game is described. The basis of the stage is the algorithm of the agreed profit distribution taking into account the activity of agents. The developed software product allows you to automate the practical calculations of the stages of the mechanism.
Application of the variational method for studying stability of the 3D Lotka — Volterra system
Authors: Tikhomirov V , Isaev R
Published: May 2021

The paper investigates the stability of the Lotka — Volterra dynamic system ≪predator — two preys≫ with the help of variational method. This method is applicable for studying equilibrium stability non-linear dynamical systems of any kind and in any dimension. It approves its effectiveness even in cases where the use of the Lyapunov function causes great difficulties (for example, when solving tasks of large dimension). The proposed method is based on a variation method for estimating the rate of phase-state metric change for the perturbed system when the variable t → ∞. The disadvantage of the variation method is the fact that this method provides only the necessary conditions of stability. However, its it forms the first step in studying the stability of non-linear dynamical systems of any kind and any dimension.
Algorithm and model for improve the avoiding of deadlock with increasing efficiency of resource allocation in cloud environment
Authors: Bondarenko Yu V , Azeez A E
Published: May 2021

Recently, cloud computing has been the most popular method among all other promising technologies that provides the service for many users at the same time. all users can reach and use the resource that is provided by the Virtual Machines (VMs). Hence users process, data must arrive to the resources to perform as a disturbed system, which provides dynamical scale services and virtualized resources. As a result of limitation of resources, the deadlock status may occur in such type of systems. In this paper, we have designed an algorithm that could increase the efficiency of deadlock avoidance. Our technique will use the attribute of execution time in the process to get better resource allocation in additional to the checking system to stay in safe state and free of deadlock.
Analysis and visualization in graph database management systems
Authors: Dubrovin A S , Ogorodnikova O V , Tsarkova E G , Andreeva E A , Kulikova T N
Published: May 2021

The following questions of visual interpretation of the data in the graph models of data are considered in the work with graph database management system (DBMS) with DBMS Neo4j as an example; convenience of data visualization in the form of graphic images as compared with the electronic worksheets was confirmed; a high connectivity of data was revealed for DBMS NEO4j. To do all these algorithms from DBMS NEO4j library are employed. Clusterization is applied for the estimation of the quality of affinity for the predetermined data sets. Here method of silhouette assessment is used. Basing on the performed experimental studies a conclusion was made concerning the quality of revealing the similarity between the predetermined data sets with the use of graph DBMS NEO4j.
On Undecidability of Subset Theory for Some Monoids
Authors: Dudakov S M
Published: May 2021

Early we (with B. N. Karlov) have proved the following claim for the infinite cyclic monoid ℋ. Let exp ℋ be an algebra of finite subsets of ℋ with the same operation, exp ℋ must be a monoid again. So the theory of exp ℋ is equivalent to elementary arithmetic. Thus, the theory of the monoid exp ℋ is undecidable. Here we consider an arbitrary commutative cancellative monoid ℋ with an element of infinite order, and generalize the previous claims to the corresponding monoid exp ℋ.