bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Space-Time Autoregressive Modelling with Time Correlated Errors for The Number of Vehicles in Purbaleunyi Toll Gates
Authors: Mukhaiyar U , Nabilah F T , Pasaribu U S , Huda N M 
Published: June 2022

Abstract
The space-time modelling considers the observations dependence based on time and spatial simultaneously. One of popular models used is the Generalized Space-Time Autoregressive (GSTAR). Most of the GSTAR class models assumed that the errors are uncorrelated and normal distributed. In fact, the dependence of errors is exist. In this paper, the GSTAR model is assumed to have the time correlated errors. The convergence of the parameter estimators is evaluated and the weak consistency is obtained. The illustration is performed by using the number of vehicles passed through Purbaleunyi toll gates. For this data, the GSTAR models be applied and compared between the uncorrelated and time correlated errors assumption of modeling. It is obtained that the GSTAR(1;1) model with time correlated errors, is more appropriate model to predict the number of vehicles passed through the Purbaleunyi toll gates. This appropriate model is well performed when the minimum number of time observations is more than sixty observations.
Natural, Meteorology, And Novel – IAP Data Processing Method for Tipping Bucket Based Rain Gauge
Authors: Rachmawati L M , Mardiansyah A , Kinanti I W , Ramadhan A , Adiwidya A S , Jalasena A , Chandra I 
Published: June 2022

Abstract
Air pollution transport is entangled with weather and climate factors. As the pollutants tend to move due to the metrological condition. Naturally, pollutants will be deposited to the ground at the end part of the deposition cycle. One of the factors of pollutant deposition in a wet deposition is rain. The soluble pollutants and particulate matter are precipitated to the earth’s surface during precipitation. In order to analyse it, we need a rainfall measuring device/rain gauge, as rainfall is an important parameter to find the correlation between the two. However, there is a limited number of rain-gauge in Indonesia. Thus, we proposed a tipping bucket rain gauge, which consists of a funnel, a bucket, a magnetic switch sensor, and a microcontroller-based processing unit. The prototype is equipped with a GSM module so that the data can be sent in real-time via text message every minute, also an SD Card as the backup storage data. It was calibrated using ISO 17025:2005 standard, the result obtained by a resolution of 0.2 mm/tip with a capacity of 4.2 ml buckets, and U95 uncertainty of ±0,04 - ±0,12 mm/minute. To find the suitable method of rainfall calculation for the prototype, we observe three methods, Natural, Meteorology, and Novel-IAP. From the three we found, Novel-IAP has the best result since the calculation is executed every second. And the other methods are found to have a high error result.
Spatial Modelling of Indoor Air Pollution Distribution at Home
Authors: Putri A N A R , Salam R A , Rachmawati L M , Ramadhan A , Adiwidya A S , Jalasena A , Chandra I 
Published: June 2022

Abstract
In ancient times, humans were very accustomed to depending on nature, so that in the past humans held the title as an outdoor species. Over time with many technological advances, the pattern of human life has shifted to being an indoor species. Currently, almost 55% of the world’s population lives in urban areas and is projected to increase to 68% by 2050. Based on the National Human Activity Pattern Survey (NHAPS), the total time humans spend indoors is 86.9%. Research shows that air pollutants contained in indoor air are 2 to 5 times more than outdoor air. The neglect of the air conditioning system also worsens indoor air quality. It is often found that the supply of fresh air and the concentration of pollutants in the work or activity zone is unknown, even though this is a crucial matter. With the amount of time spent indoors, air quality and the distribution of pollutants in indoor air becomes very important. This research was conducted spatial modelling of air pollutant distribution using the kriging interpolation technique. The results of spatial modelling with this method produce an average of R-squared=70,98% dan RMSE = 0.03. Several factors influence the increase in pollutant concentrations that are the activity of the occupants, the number of occupants, and environmental conditions outside.
A Simple and Low-cost Photocatalytic Air Purification Test Method
Authors: Adhi P M , Rahman H , Nuriskasari I , Syamsudin  , Syahrom A 
Published: June 2022

Abstract
The application of photocatalytic oxidation (PCO) in air purifiers (AP) to remove viruses, bacteria, and toxic gases in the air is intensively being studied, especially after the Covid-19 pandemic broke out. The testing method of PCO materials for AP purposes has been standardized through ISO 22197-4 (2013). However, the standard required a set of complex, high precision, and costly equipment. The present study demonstrates a simpler and low-cost test setup without compromising any accuracy in the overall result. The proposed test consists of a test chamber and mixing chamber, and sets of equipment installed in it. A 3D printer fabricated a PCO reactor, and TiO2 was coated on the surface. Formaldehyde (HCHO) is used as a sample pollutant to be observed, injected into the test chamber. Before the measurement of the concentration of HCHO, the intensity of UV A LED was measured. Then, the amount of formaldehyde concentration was monitored online by indoor air quality measurement equipment. The result shows that the intensity of UV light was enough to generate a photocatalytic oxidation reaction. After 20 minutes of reaction, the HCHO concentration inside the chamber was decreased around 21.76%.
Analysis of seawater intrusion into groundwater in the coastal area of Durung Village, Aceh Besar Regency, Aceh Province, Indonesia
Authors: Arfah M , Tanjung M , Syahreza S , Hartati D V 
Published: June 2022

Abstract
Durung Village is a region consisting mostly of coastal and hilly areas. Utilization of groundwater in the coastal zone has been increased these recent years for all purposes of life, from drinking to sanitation and from industry to agriculture. It results new environmental problem, such as seawater intrusion that caused negative impact on groundwater resources. This research aims to analyze the effect of seawater intrusion into the groundwater in the study area. Total Dissolved Solids (TDS) was used in this research as approximation of groundwater salinity value. The spatial distribution of seawater intrusion had been prepared by using Geographic Information System (GIS) spatial interpolation technique for TDS parameter. The results revealed that seawater intrusion presented more obviously near the coastal line and its northern part was the most affected area by this contamination indicated by the highest TDS value of 2.947 mg l-1, whereas the farther location from the coastline were free of seawater intrusion indicated by low TDS values between 181 – 579 mg l-1.
Experimental investigation of pile characteristics of non-spherical particles mixtures: pile height and angle of repose
Authors: Widartiningsih P M , Putra M I R , Aji D P P , Rudiawan A N F , Viridi S 
Published: June 2022

Abstract
An angle of repose is defined as the steepest angle of a conical pile that is naturally formed when a bulk of particulate solid is poured onto a flat surface. It has been considered as one of the important properties in characterizing granular material due to its effectiveness in determining flowability of granular, pile profile in an opaque container, and granular transportation system. Since the angle of repose is sensitive to the shape of individual particles, investigations through experiments and simulations for various forms of particles have been carried out. However, most of them were performed under homogeneous particle systems. While in practical situations, granular mixtures consisting of a variety of particle shapes are commonly employed. This study presents an experimental investigation of angles of repose resulting from a mixture of two types of non-spherical particles with different values of roundness. Experiments have been carried out with different compositions and have been repeated five times to ensure their reproducibility. The results show that the angle of repose linearly corresponds to the granular composition, where the coefficient of determination is ~0.95. Therefore, the effect of granular composition in binary mixtures on the characteristics of the resulting pile has been demonstrated in this study.
Geometry Effect of CaCl2·6H2O at Charging and Discharging Process as Latent TES
Authors: Yusuf Akhmad , ‘Ulhaq S D , Wonorahardjo S , Sutjahja I M 
Published: June 2022

Abstract
Phase Change Materials (PCMs) as thermal energy storage can store a relatively large amount of latent heat at a relatively constant temperature during the solid to liquid (melting process), or vice versa. With many applications of PCM as temperature regulation such as for building application, heating, or cooling devices for battery, electronic, food preservation, and medicine, the geometry effect is significant to optimize its performance because each type of application requires a specific kind of geometry. This paper reports the simulation study for the charging and discharging an inorganic PCM of CaCl2·6H2O (melting temperature 29 °C) using Ansys fluent for various 3D and 2D geometric shapes, consisting of the sphere, cylinder, and rectangular solid. The density, heat capacity, thermal conductivity, and viscosity as the input parameters were taken or extrapolated from previous experimental studies. The simulation study results consisting of time-dependent temperature for melting and freezing transition and time-dependent liquid mass fraction can be used to optimize the CaCl2·6H2O as the medium of thermal energy storage (TES) as the medium of thermal energy storage (TES) for a specific application.
Absorber Geometry Size Optimization For Acoustic Anechoic Chamber Design Using Genetic Algorithm
Authors: Christian J , Suprayogi  , Fitriyanti N 
Published: June 2022

Abstract
An anechoic chamber is a room that is made to resemble the condition of empty space. This room has an absorption rate of 99%. The absorber is an essential part while manufacturing an anechoic chamber. In an anechoic chamber, absorber affects in terms of absorption and frequency range. Specification of the absorber used depends on the specification of the anechoic chamber to be made. The optimum absorber geometry size is required to maximize the net volume of the anechoic chamber. The maximum measurable object size is 0.05x net volume of an anechoic chamber. To overcome the problem, it is necessary to optimize the size of the absorber geometry. The size optimization of the absorber geometry has been carried out using a genetic algorithm with MATLAB as the programming software. The incidence angle of the wave and the width of the absorber are used as input parameters for absorber optimization. Absorber geometry size optimization results in an optimum peak angle and absorber length. The width of the absorber used in this optimization is 0.2 m. The peak angle obtained is 12.2° with a length of 0.936 m. The average absorption coefficient obtained is 0.886041.
The Optical Response of Metallic Spherical Core-Shell Nanoparticles
Authors: Fitriyadi  , Azwar Azrul , Noor Fatimah Arofiati 
Published: June 2022

Abstract
The optical response of spherical nanoparticles was studied based on the quasi-static approximation of classical electrodynamics. The simple Drude model was used to calculate the complex dielectric function of the metal. We investigated the behavior of the absorption cross-section spectra of metallic spherical core–shell (including dielectric-metal and metal-dielectric) nanoparticles numerically. We found that the number of resonance peaks in the absorption cross-section spectra depends on the number of metal-dielectric interfaces of the nanostructure, as predicted by plasmonic hybridization theory. Furthermore, the absorption cross-section spectra can be precisely controlled by changing the thickness of the shell and the dielectric constant of the medium.
Calculation of spectra and plasmon wave distribution in one-dimensional periodic structure
Authors: Fariz Alvin , Hidayat Rahmat 
Published: June 2022

Abstract
Surface Plasmon Resonance (SPR) is a resonance phenomenon between electromagnetic waves and electrons, which is formed on the interface between metal and dielectric surface. SPR waves can be generated by using a coupler element, such as prisms and gratings. In this study, we analyzed the effect of groove filling in nanograting structures using computation work based on Rigorous Coupled Wave Analysis (RCWA) method. The structure periodicity is 700 nm with a groove depth of around 350 nm. The reflectance spectra calculation by the RCWA method produces the appearance of SPR dip for an empty groove (with air inside the groove) at around 550 nm - 650 nm. The dip wavelength varies on the incident angles from 30 up to 60 degrees. In addition, the shifting of those dips is also predicted from the calculation results when the groove is filled by a medium with a refractive index of 1.5, which can be the basis of its utilization as optical sensing elements.
Density Functional Theory Study of Oxygen Deficiencies in SrCoO25
Authors: Wilbert Kevin , Pradipto Abdul-Muizz , Agung Nugroho A. 
Published: June 2022

Abstract
We report the effects of oxygen deficiency to the electronic and magnetic properties of SrCoO3 calculated using spin-polarized Density Functional Theory. The correlation effects of the Co 3d orbitals are considered explicitly using the effective Hubbard U
eff parameter. The U
eff consists of the subtraction between the U value of 3 eV to denote the Coulomb interaction and the Hund’s coupling parameter J of 0.95 eV. Our results show that the localized character of the Co 3d orbitals strongly depends on the oxygen content. The magnetic exchange interaction between two neighboring Co ions is therefore altered. As a consequence, a change of magnetic ground state using the same U
eff value from ferromagnetic ordering in full oxygen content to antiferromagnetic ordering in SrCoO2.5 is obtained.
Possible signature of entanglement in null-energy-condition-violating inflation
Authors: Prihadi H L , Zen F P 
Published: June 2022

Abstract
In recent years, the classical version of the null energy condition (NEC) has been enhanced into its quantum generalization, the quantum null energy condition (QNEC). The right-hand side of the QNEC inequality is non-zero; it is multiplied by a factor of ћ and recovers the standard NEC in the classical limit. Moreover, the second derivative of entanglement entropy also plays a role in determining the right-hand side. In this work, we study several examples of theories of inflation that violate the standard NEC, yet still, possibly obey the QNEC. This suggests that the deviation of the standard NEC arises due to the existence of entanglement between regions inside and outside of the cosmological horizon. Possible connection to quantum fluctuations of de Sitter spacetime is also studied.
Analysis of gravitational waves from inflation model with minimal, non-minimal, and non-minimal derivative coupling of scalar field from Horndeski theory
Authors: Djogama M Z , Hikmawan G 
Published: June 2022

Abstract
Inflation theory provides solutions for problems in cosmology, such as horizon problem and flatness problem. The study of Gravitational waves production in cosmic inflation era not prove the general inflation theory, but also to differentiate in detail among specific models. In this research, we use inflation model with minimal, non-minimal, and non-minimal derivative coupling of scalar field without potential from Horndeski Theory. From this model, we calculate scalar and tensor perturbation equations and then obtain its equation of gravitational waves, spectral index for each perturbation mode and tensor-to-scalar ratio. Spectral index and tensor-to-scalar ratio nearly scale-invariant and agree with observational data for some Ho, ζ, and ξ. Gravitational waves remain constant during inflation and start oscillates when its modes enter the horizon. Energy of this gravitational waves is scale-invariant for modes that re-enter horizon during radiation dominated era and rises toward lower frequencies.
Numerical Analysis of Non-minimal Coupling and Non-minimal Derivative Coupling Models using Direct Random Method
Authors: Rusyda M B , Suroso A , Hidayat W 
Published: June 2022

Abstract
In this work, we studied classes of Horndeski theory, specifically the Non-minimal Derivative Coupling (NMDC) ‘model and Non-minimal Coupling (NMC) model, against the observation of gravitational waves using the numerical framework given by Arai and Nishizawa. The framework takes randomized set of parameters of the theory, filters results that disagree with the late-time evolution of the universe and the stability condition, and outputs observable quantities of gravitational waves (GW) that were then compared to the quantities obtained from observational data of gravitational waves detection.
Study on optical properties of carbon nanodots by annealing of rice powder as a carbon source
Authors: Jaya M. , Johanes A. Z. , Pingak R. K. , Ngara Z. S. 
Published: June 2022

Abstract
In this work, we present the fabrication process and analyze the optical properties of carbon nanodots (C-dots) from rice powder taken from Kupang regency, East Nusa Tenggara Province. The rice powder was annealed at 400oC for 30 minutes to obtain a black powder. This sample (0.5 gram, 3 mL ethanol) was sonicated for an hour, and ethanol (10 mL) was added again for the centrifugation process at 1000 rpm for 20 minutes. Furthermore, the ethanol solution was filtered to realize C-dots. By irradiation with a UV lamp at 365 nm, C-dots emitted blue emission color, and they have absorption peaks at a wavelength of 276 nm. Upon excitation wavelength (λexc) of 350 nm, their fluorescence (FL) spectrum range is from 360 to 650 nm with maxima FL intensity at 436 nm corresponding to blue emission color as well as high photostability. The appearance of O-H and C=O bonds indicates that the surface of C-dots was coated with hydroxyl and carbonyl groups. Therefore, the blue emission color and excellent photostability of these C-dots can pave a large opportunity to explore the C-dots from rice powder as a functional material in electronic devices such as sensors, light emitting diodes, and so on forth.
Preparation of Bimetallic Metal-Organic Framework Derived from Spherical Ni-Co Glycerate Template
Authors: Adli Muhammad Zimamul , Irzaman  , Nugroho Widagdo Sri , Rusydi Febdian , Nugraha  
Published: June 2022

Abstract
Bimetallic Metal-Organic Frameworks (MOFs) have attracted significant interest due to its high specific surface area and tunable porosity, leading to high sensitivity and catalytic activity. Amorphous MOF presents many opportunities as new functional materials especially in electrochemical applications. In this preliminary study, we explored the preparation, properties, and applications of amorphous MOF. It studies on the characteristics of Ni/Co-MOF synthesized through self-template using uniform Ni-Co glycerate spheres. Nickel and cobalt are active electrode materials with similar properties and atomic radius, and have much possible coordination with ligands so that they can be found in many types of MOFs. In this work Ni-Co Glycerate, produced in powder form, was used as the source of metal ions, 2-methylimidazole (H-MeIM) as the ligand, as well as aquabidest and ethanol as the solvents. The MOF was produced in two-step processes i.e. glycerate formation with solvothermal and MOF formation at room temperature. From the XRD test, no peak was observed, showing that the Ni/Co-MOF is in an amorphous phase. The results of the Scanning Electron Microscope (SEM) analysis showed that the Ni/Co-MOF has spherical shape covered by nanosheets, confirming the amorphous state.
DFT study on gas-phase decomposition of ethylene carbonate in the presence of LiPF6, LiBF4, PF6
-, and BF4
-
Authors: Naufal F D , Lasiman E T , Syafira A Z F , Anshor M F , Setianto D , Ubaidillah A , Rendy B , Komalig R W M , Nuruddin A , Saputro A G , Shukri G 
Published: June 2022

Abstract
The decomposition of Li-ion battery (LIB) electrolyte has been a well-known challenge that needs to be overcome. The most common electrolyte on lithium-ion batteries is LiPF6 which has all-balanced properties, while LiBF4 has been proven for its superior stability. These lithium salts are often dissolved in Ethylene Carbonate (EC) to form liquid electrolyte systems. In this work, we investigate the decomposition mechanism of EC in the presence of LiPF6, LiBF4, and their delithiated counterpart by means of first-principles density functional theory (DFT) calculations. We found that the energy barrier of decomposition on LiBF4 presence is 0.42 eV lower than on LiPF6 presence, also on BF4
- presence is 0.22 eV lower than PF6
- presence. This suggests that LiBF4 and BF4
- presence reduces EC stability more than LiPF6 and PF6
- anion. Moreover, the presence of Li+ ion increases the energy barrier of decomposition (about 0.79 eV on PF6
- case, 0.59 eV on BF4
- case) but decreases enthalpy change significantly (about 1.58 eV on PF6
- case, 1.43 eV on BF4
- case). This suggests that while the Li+ ion causes the decomposition to be slower, its presence destabilizes the EC more.
Building a Science Kit of Faraday’s Law with Free Fall Motion Method
Authors: Lutfiana S , Pujayanto  , Haryani F F 
Published: June 2022

Abstract
The aim of this study is to build a science kit of Faraday’s Law with free fall motion method. The magnetic flux comes from several neodymium magnets and the coil is made of copper. The moving magnet falling through the coil causes a change in the magnetic flux and produces an induced emf. The data analysis technique used in this research are graphical method and analysis of Faraday’s Law equations with another supporting equation. Based on the results of this study, the conclusion is the induced emf value is directly proportional with the change of the magnetic flux and also has a directly proportional with the number of turn of coil, thus it can be obtained the mathematical equation of Faraday’s Law

ε
=

d
ϕ
B

d
t
Study of Eclipsing Binary Physical Parameters. Case: CV Boo
Authors: Rahma Aliyya Nur , Putra Mahasena , Hakim Muhamad Irfan , Aprilia  , Sugianto Yayan 
Published: June 2022

Abstract
Eclipsing binary (EB) is a binary system in which the components are seen eclipsing each other from the Earth. Photometric and spectroscopic observation of EBs show variation on their brightness (light curve) and radial velocity (velocity curve). Light and radial velocity curve analysis provide physical and geometrical parameters of the binary systems and their components, which are very important in stellar evolution studies. These parameters are determined by solving inverse problem, i.e. finding the best-fitting model to the observational curves. Modern EBs modeling programs include detailed physics of stellar atmosphere, geometry, and dynamics of the binary system. One of such models is PHOEBE (PHysics Of Eclipsing BinariEs) 2.3, which offers sophisticated methods to solve the inverse problem. It is solved by computing model curves from initial (estimated) parameters, optimizing them numerically, and sampling the optimized models. We studied CV Boo, a detached EB with a period of 0.847 days, using PHOEBE 2.3. Light curve and radial velocity curves were obtained from the literature. We discuss the steps in finding the solution, present our best solution of the inverse problem, and compare our results with previous studies.