bluuebunny/crossref_metadata_2025_split huggingface dataset:
Hydrological system modeling: Approach for analysis with dynamical systems
Authors: Redondo J M , Ibarra-Vega D , Catumba-Ruíz J , Sánchez-Muñoz M P 
Published: June 2020

Abstract
Recent methods for sustainability analysis have involved the methodology of system dynamics for the representation of different landscape components that are analyzed. This document proposes a mathematical model based on system dynamics for the hydrological component in the sustainability analysis that includes the processes between precipitation and runoff. Additionally, the stability of the equilibrium point found with the theory of dynamic systems is studied. The modeling is carried out from a diagram of levels and flows, in order to obtain a system of ordinary differential equations of first order, linear, non smooth, that takes as state variables static and capillary storage, superficial storage, higher gravitational storage, lower gravitational storage (aquifer) and storage in the channel. The model was validated with time series of the Chinchina basin (Caldas, Colombia). From dynamical systems point of view, the system behavior has an equilibria point that depends on the saturation value in the static and capillary storage.
Learning the concept of integral through the appropriation of the competence in Riemann sums
Authors: Aréchiga Maravillas J , Arceo-Díaz S , Salazar-Torres J , Andrade D Sierra , Montes M Benites 
Published: June 2020

Abstract
It is proposed that the difficulty of engineering students into understanding the concept of the integral, as a way for calculating the area under a curve, can be overcame if students are taught how to translate it into the problem of calculating a Riemann sum. A series of applied problems are proposed to provide a frame that required to calculate the area under a curve to two groups of students. For one of these groups, Geogebra was proposed as a tool that could be used to maintain the focus of students into the concepts, by providing ways to easily calculate and visualize the solutions, while the other group reached to the solutions by analytically making all the calculations. Evidence was found that, to a confidence level of 95%, Riemann sums calculated with Geogebra reduce the score difference in context problems requiring the calculation of integrals, helping students to reach a better understanding on the concept of the integral as the area under the curve of a given function.
Impact of a basic mathematics course on the performance of college students in algebra subject
Authors: Villanueva-Cantillo J , Orozco-Guzmán M , Mejía Acuña F , Obredor Castro S , Silvera Malo E 
Published: June 2020

Abstract
A common problem for universities is the lack of knowledge and mathematical skills of new students because this deficiency creates difficulties in their studies throughout their career, which can cause their dropout. The aim of this paper is to describe the impact of a basic mathematics course on the performance of college student in algebra subject. This is a 32-hour course which is developed in 16 sessions in parallel to the algebra classes and is mainly offered to students: a) identified with low performance on mathematics component of national high-school test, and b) remitted by the subject teacher. The main findings are: a) the pass rate for students who attended to more than half of the sessions of the course if 95%, and b) the average grade of the subject tends to increase as with the attendance level to the course of the students. Consequently, these results lead to the conclusion that the course has a positive effect on the students’ performance.
Development of random thinking: Reflections and considerations
Authors: Salazar-Torres J , Vera M , Rincón O , Omaña L , Lizcano L , Huérfano Y , Vargas D 
Published: June 2020

AbstractThis article discloses some considerations and reflections in the teaching of random thinking and data systems based on a documentary review. A documentary sample was used consisting of 40 documentary sources (articles, postgraduate dissertations and books), published in indexed journals, about random thinking. The research was based on a qualitative content analysis method which used the coding and categories saturation process. The results let us establish conceptual relationships considering three dimensions linked to the random thinking teaching, they are: epistemological corpus, theoretical corpus and the social function. The results allow to base new proposals of curricular, didactic and evaluative type for the teaching of this thinking, at the same time, it allows to carry out processes of self-assessment of the teaching practice and of the need that currently exists before the research in the classroom and the contextualization of mathematical knowledge.
The rubric as an assessment strategy in the mathematical argumentation process
Authors: Salazar-Torres J , Vera M , Contreras Y , Gelvez-Almeida E , Huérfano Y , Valbuena O 
Published: June 2020

Abstract
The article shares the proposal of an analytical rubric as a strategy for the assessment and monitoring of learning outcomes in students who develop an argumentative plot from the mathematics field, to solve any problem situation in daily life. The study was based on the theory of mathematical argumentation proposed by Duval and the contributions of León and Calderón, as well as the dimensions presented to us by the logical frameworks in the design of analytical rubrics. The research was developed under the social critical paradigm through the design of pedagogical action research, and the focus group technique was used for the collection of information composed by five professors from the department of basic sciences. As a result, a collective rubric that, in addition to generating processes of self-assessment and self-training in teachers, evidences a decrease in the existent subjectivity of the evaluation processes, thus strengthening its objectivity.
Spatial concepts in individualization, subjectivities and singularization processes
Authors: Acevedo-Rincon J P 
Published: June 2020

Abstract
Perception of space and its surroundings develops from the first months after birth. The notion of spatiality is present in the daily life of the baby. From the moment he begins to know his body, the baby identifies the part and the relationship with the whole (of his body) of the sensory. That is why, when talking about spatial perception, we do not necessarily limit ourselves to the schooled knowledge governed by the school curriculum. The present writing intends to approach the notions of space and spatial sense since the early years, from the reading of the cartographies developed in different kindergartens in Brazil and Colombia. This paper reflects on the processes of singularization, subjectivities, and individuation that involve the baby’s early learning. This text offers approaches to the development of the notion of space in the baby. This research is of an interdisciplinary approach, which adopts a qualitative methodology with a descriptive perspective. Among the most important results are presented the cartography of the paths and the relations of babies, by experimenting the space related to the processes of individuation, subjectivities and singularization lived in various places for babies.
Determination of mean local time on the day of the anomaly on LEO spacecraft
Authors: Ahmad Nizam 
Published: June 2020

Abstract
Numerous spacecraft have been reported to experience failures or anomalies due to various sources such as solar and geomagnetic storms. One of the important keys to investigate anomalies on spacecraft is satellite local time (SLT) utilized to track satellite position in space. Since not every local time of anomaly was registered and recorded well especially for low Earth orbit (LEO) spacecraft, it is necessary to find a method to determine SLT. A Simplified General Perturbations-4 (SGP4) method has been applied to overcome the absence of SLT information in the satellite anomaly database. A series of DMSP satellites are employed for the case study. In addition, the AACGM model is also taken into account for mean local times (MLTs) calculation. The discrepancy of MLTs is found between the observation, calculation and AACGM model and supposedly comes from the TLE data, which seemingly gives rise to incorrect orbital parameters. The deviation of MLTs leads to different morphology of MLT distribution in which the observed MLTs scatter from dusk to midnight sector, whereas the others spread within the dusk and noon sectors of MLT.
The Utilization of Bayesian Framework in Determining Projected Spatial Distributions of Star Clusters
Authors: Hidayat Y A , Arifyanto M I , Aprilia  
Published: June 2020

Abstract
Star clusters are groups of stars that are bonded to each other by their gravitational forces. In general, star clusters are divided into the globular cluster and open cluster. There will always be some dynamic interactions in their lifetime, i.e. the process of relaxation and equipartition of interstellar encounter energy. The modeling is done by using King, Generalised King (GKing), Optimised Generalised King (OGKing), Elson Fall Freeman (EFF), Generalised Density Profile (GDP), and Restricted Generalised Density Profile (RGDP) profiles. Based on the Bayes factor, the results of a review of the density structure for star cluster Blanco 1 are dominated by King group profiles (King, GKing, and OGKing). Ellipticity values at the core radius (ϵrc
and tidal radius (ϵrt
obtained are

0.07

−
0.01

+
0.56

and

0.10

−
0.01

+
0.66

, respectively. The estimation of the occurrence of mass segregation can be viewed from the value of κ. The κ valued obtained for Blanco 1 is

0.06

−
0.24

+
0.10

means that it undergo some mass segregation. The total mass obtained using the tidal force relationship of gravitational interactions with the potential Galaxy is

1623

−
364

+
273

M
⊙

.
Diffuse Interstellar Bands (DIBs) on the spectra of GALAH data: Correlation study between DIBs and DIBs with color excess
Authors: Istiqomah A N , Puspitarini L , Arifyanto M I 
Published: June 2020

Abstract
Diffuse interstellar bands (DIBs) are a collection of weak interstellar absorptions in the spectra of reddened objects. We have successfully measured three strong DIBs (i.e., λ 5780, 5797, and 6614 Å) on the spectra of 125 Galactic Archaeology with HERMES (GALAH) target stars. The fitting uses a template spectrum in order to extract and measure individual DIB. We applied a correlation study between DIBs and confirmed that DIBs are positively correlated with each other, meaning that their carrier(s) are co-existing in the interstellar medium. Also, DIBs are well-correlated with color excess E(B-V). From this result, which is in a good agreement with earlier studies, conclude that DIBs can be used as a tracer of the interstellar medium.
Analysis of binary star cluster candidates with Gaia DR2
Authors: Naufal A , Arifyanto M I , Aprilia  
Published: June 2020

Abstract
Two star clusters can be located near each other as a result of either simultaneous birth or system encounters, and thus are called a binary star cluster system. We analyzed three candidates of binary cluster: ASCC 16-ASCC 21, NGC 6716-Collinder 394, and NGC 2547-Pozzo 1 based on Gaia DR2. Each pair have physical separations of 13 pc, 13 pc, and 42 pc. In order to constrain the binarity of the candidates, we investigated their morphology, age estimates, photometric mass, and kinematics.
Photospheric magnetic field properties of active region 12740
Authors: Nurzaman M Z , Sulistiani S , Volvacea V 
Published: June 2020

Abstract
Active regions, which are mainly responsible for the energetic blast from the Sun so-called flare, have a highly concentrated magnetic field. Almost all flares have been attributed to the dynamics of its magnetic field on the photosphere. One method to know the changings is through studying their properties using magnetogram data. The data that are obtained from Helioseismic Magnetic Imager (HMI) instruments onboard Solar Dynamics Observatory (SDO) have a good temporal resolution which can make a better analysis. We analyze three properties of photospheric magnetic field namely total photospheric magnetic free energy (TOTPOT), total unsigned vertical current (TOTUSJZ) and total unsigned current helicity (TOTUSJH) of the active region (AR) 12740 which produced almost M-class flare at the very minimum phase of solar cycle 24. Then, we compared their values to the average values of all the corresponding parameters for almost one solar cycle. The results showed that the values of each parameter in AR 12740 was below the average values of C-flare-productive ARs. The TOTPOT was half of the average while TOTUSJH and TOTUSJZ were around one-third of the average.
Spectroscopic observations of emission-line objects at Bosscha Observatory
Authors: Rafif Rabbani M , Adhyaqsa Azlizan , Prabowo Dimas A , Aprilia  , Puspitarini Lucky , Malasan Hakim L 
Published: June 2020

Abstract
We report an optical spectroscopic observational program of emission-line objects at Bosscha Observatory. The observations were conducted on 18 nights between May to July 2019. We employ the spectrograph NEO-R1000 (R∼1000) equipped with SBIG ST-8 XME CCD camera attached to a 28 cm (F/10) telescope and the spectrograph LHIRES III (R∼5000) equipped with SBIG ST-402 CCD camera attached to a 25 cm (F/10) telescope. Data reduction has been carried out using longslit transform routines within the Image Reduction and Analysis Facility (IRAF). We have successfully obtained the spectra of 9 Wolf-Rayet (WR) stars, 13 B-emission (Be) stars, 2 Luminous Blue Variable (LBV) stars, 8 Herbig Ae/Be (HAeBe) stars, and 1 recurrent nova. The obtained spectra are presented and discussed in this paper.
Atmospheric model and synthetic spectrum of LL Aquarii using Kurucz model
Authors: Saputra M B 
Published: June 2020

Abstract
Not only have interior structures, but stars also have an atmosphere. Physical processes and phenomena that occur in the atmosphere of a star also have a relationship with the stellar interior. One of them is the energy transport process produced from the stellar core and delivered to the surface and atmosphere of the star. The stellar atmospheric model is built by taking into account the changes in various parameters, such as mass depth (∫ ρ dx), temperature (T), gas pressure (Pgas
), electron density (ne
), Rosseland absorption coefficient (κR
), and radiation pressure (Prad
) to the changes in optical depth (τ) of the star. The stellar parameters used for building this model are from the LL Aquarii star which is a detached eclipsing binary star. The star system has a mass of 1.1949 M
⨀ for LL Aqr A and 1.0337 M
⨀ for LL Aqr B with effective temperatures of 6124 K and 5747 K respectively. The obtained atmospheric model is the result of bilinear interpolation of the Kurucz atmospheric grid model with Teff and g parameters. The results of the LL Aqr atmospheric model become inputs for modeling the stars synthetic spectrum using the SPECTRUM program. Convolution with the rotational velocity of the star and spectral parameters of the spectrograph instrument used will produce a synthetic spectrum that corresponds to the spectrum acquired from observations. The results showed conformity with the observed spectrum with an O-C difference of 0.05 on average.
Compaction of a two-dimensional system of composite spherical particles under the influence of self-gravitation: Between lock-and-key model and Tetris-structure
Authors: Viridi S , Dermawan B 
Published: June 2020

Abstract
A self-gravity ofspherical granular particles in the two-dimensional system is simulated. Some of the spherical particles are bonded through a spring force to form composite particles. These spherical and composite particles are attracted to each other due to gravitational force and prevented from collapse into a single point by the normal force. A previous study reported that a two-dimensional monodispersed system will form a hexagonal close-packed (HCP) configuration. In this work, it will be perturbed by some of the composite particles that could have HCP form, simple cubic (SC) form, or a mix of SC-HCP (MSH) form. These forms can be categorized into SC family (□, I, L, T, F, H, E), HCP family (Δ, □, V, X), and MSH family (⌂, K, M, W, N, Z), that can be compacted to maximum contactopy through lock-and-key mechanism (KL). The compaction of some forms from the SC family is similar to the Tetris game, where the structure should be compacted before it could be eliminated in the game. In this work, not all forms from the three families are simulated. The particles in general tend to form a final configuration with the most compact form and the composite particles seems also to influence their surrounding particles to construct the configuration.
Application of Mahalanobis-Taguchi System on Electrical & Electronic Industry
Authors: Nik Mohd Kamil N.N. , Abu M.Y. , Zamrud N.F. , Mohd Safeiee F.L. , Oktaviandri Muchamad 
Published: June 2020

Abstract
Most of Malaysia’s activities in Electrical & Electronic (E&E) Industry more focused in manufacturing industry. The E&E Industry is one of Malaysia’s leading industries that has 24.5 percent in manufacturing sector production. With a rapid expansion of E&E Industry with a continuous innovation, there is no methodological that show the optimization procedure for a process that concern on E&E product in production area. The aim of this work is to develop the optimization parameter for a process of E&E product based on Mahalanobis-Taguchi System (MTS). In methodology, the optimization parameter will develop by using four stages which are construction Mahalanobis Space (MS), validation of Mahalanobis Space (MS), identify the useful characteristic, and predict and future diagnosis. The production in the industry can reduce the rejected product in parameter in a process. Consequently, significant parameters can be identified for E&E product.
Improving productivity through value stream mapping (VSM): A case study at electrical & electronic company
Authors: Rose A.N.M. , Mohamed N. M. Z. N. , Ab Rashid M, F. F. , Noor H. M. , Mohd A. 
Published: June 2020

Abstract
This paper is aim to increase productivity of a case study’s company by eliminating of all possible non value added activities. The study is carried out at a speaker unit of ABC’s company, Malaysia. The current value stream map of production line was developed based on interviews, observations and other data of the company. Then, the future VSM was mapped based on the lean manufacturing principles. The current VSM was identified 12 NVA activities and the improved VSM managed to eliminate all 10 NVA activities. The elimination of NVAs was successfully achieved by applying selected lean tools and techniques. All hidden and cause of wastes were identified and eliminated. As a result the application of VSM has improved company performance by increasing the productivity by 35% and production lead time up to 400%.
Enhancement of Stability and Thermal Conductivity of Nanofluids Using Chinese Ink As a Surfactant
Authors: Mamat H. , Md Isa R. 
Published: June 2020

Abstract
Stability of nanofluids is a basic requirement for cooling application since it is directly related to properties of nanofluids. The objective of the present study is to compare different types of nanoparticles in water based fluids. Nanosilica, graphene and functionalize multi-walled carbon nanotubes (F-MWCNT) were dispersed in water based fluids, and chinese ink was used as a surfactant. Ultrasonication via two-step method was used to produce the nanofluids. The chinese ink have been used to reduce surface tension in fluid and minimize the sedimentation problems of nanofluids. Thermal conductivity of the nanofluids was measured by thermal property analyser. The stability of nanofluids was observed through visual observation and zeta potential measurement methods. F-MWCNT with chinese ink exhibit 79% thermal conductivity enhancement compared to the based fluid. Graphene and F-MWCNT possess zeta potential value which are more than 47 mV (negative) compared to the other tested samples. In conclusion, F-MWCNT nanofluid has a potential to be used in cooling application due to the highest thermal conductivity and nanoparticle stability.
Covalent functionalization of reduced graphene oxide using azido-terminated poly(2-isopropyl-2-oxazoline)
Authors: Abdullah Nabihah , Ifraan Muhd Dzul , Mat Yahya Nor Aisyah , Hashim Norazlina , Abdullah Suhaila , Mohamed Rabiatul Manisah , Kubo Masataka 
Published: June 2020

AbstractAzido-Terminated Poly(2-isopropyl-2-oxazoline)(N3-PIPOZ) was prepared and it was then functionalized onto reduced graphene oxide (rGO). rGO was prepared from the reduction of graphene oxide (GO) by using hydrazine. The exfoliation of GO was measured using UV-Vis Spectroscopy. As a result, covalent functionalized reduced graphene (rGO-PIPOZ) with good solubility was successfully produced using grafting-on technique. Fourier transform infrared (FTIR) and thermogavimetric analysis(TGA) results proved the attachment of PIPOZ macromolecules onto rGO. rGO-PIPOZ showed best solubility in methanol (MeOH). The production of rGO- PIPOZ can be facilitated to a broad range application of graphene such as in polymer nanocomposites and lithium ion batteries.
Adsorption of Heavy Metals on Banana Peel Bioadsorbent
Authors: Mohamed Rabiatul Manisah , Hashim Norazlina , Abdullah Suhaila , Abdullah Nabihah , Mohamed Amri , Asshaary Daud Mohd Abu , Aidil Muzakkar Kaha Fakrul 
Published: June 2020

Abstract
Heavy metals have become a serious pollutant in water as a result of its non-biodegradable and toxicity properties. In this research, banana peel was synthesized as bioadsorbent to remove heavy metals from contaminated water. The major problem associated with banana peel bioadsorbent is that the activated carbon produces from biomass materials possess insignificant adsorption capability compared to its commercial counterpart. Besides that, large quantity of banana peel wastes contributes to its significant disposal problem. Thus, the present work is expected to solve the problems of banana peel disposal by converting it into bioadsorbent. The objectives of this research are to synthesize banana peel bioadsorbent and to evaluate heavy metals adsorption performance of the banana peel bioadsorbent. The bioadsorbent were treated using KOH in its preparation. The materials then undergo characterization using FTIR and AAS. The carboxylic and hydroxyl functional groups were confirmed by FTIR. The maximum removal efficiency for Pb and Fe ions were 100% and 64% respectively. The comprehensive utilization of low-cost raw material as bioadsorbent in wastewater activities are highly suggested due to its facile processing, abundantly available and environmental friendly.
Extraction of Polyhydroxyakanoate (PHA) from Palm Oil Mill Effluent (POME) using Chemical Solvent Extraction
Authors: Shakirah H.L. , Zulilah Z.N.A. , Aniyyah M.S.N. , Nabihah A. , Radhiah G.S. 
Published: June 2020

Abstract
Palm oil mill effluent or POME is the waste water discharge from palm oil milling activities. Polyhydroxyalkanoate or PHA is the linear polyester that produces by bacterial fermentation of sugar or lipids with nature process. The objectives of this research are to extract PHA from POME using chemical solvent and to study the percentage of purity and recovery of PHA. A methodology was developed for PHA extraction from palm oil mill effluent using chemical solvent. PHA from POME can be extracted by using chemical extraction method by using non halogenated solvent that are acetone, methyl isobutyl ketone and ethyl acetate. The result show percentage of mass PHA recovery with acetone has high percentage that is 93% follow by ethyl acetate with 81.2% and lastly with methyl isobutyl ketone with 66%. Meanwhile, the PHA purity percentage by using acetone is 71%, follow by ethyl acetate 58% of purity obtain lastly methyl isobutyl ketone with 49% PHA purity obtain. PHA can be extracted from POME using chemical solvent extraction method.