bluuebunny/crossref_metadata_2025_split huggingface dataset:
Graphical interface of geographically weighted negative binomial regression (GWNBR) model using R-Shiny
Authors: Yasin H , Suryani I , Kartikasari P 
Published: July 2021

Abstract
In regression analysis, the spatial aspects need to be considered because each region has different characteristics as well as the Poisson regression model. In this method, some assumptions must be fulfilled, namely that the variance and the mean of the response variable are equal. However, counted data often have a greater variance than the mean, or what is generally called the over-dispersion phenomenon. If over-dispersion occurs, the Poisson regression is not suitable for modeling data, and that will produce biases in the parameter estimates. One method used to overcome over-dispersion in Poisson regression is negative binomial regression. The negative binomial regression model is more flexible than the Poisson regression model because it assumes that the mean and variance are not necessarily equal. Therefore, if the spatial aspect is considered, the Geographically Weighted Negative Binomial Regression (GWNBR) method is used. This study aims to compile a computational application to model spatial data using GWNBR Model using R-Shiny Web Application. And, the GWNBR model will be applied to modeling the number of dengue cases in Central Java province. The GWNBR model with Adaptive Boxcar weight is the best model because it has the smallest AIC. Using this model, two groups of districts/cities are obtained based on significant variables.
The technology of rob water treatment becomes clean water by using the combination of electrolysis, filtration, and ozonation methods
Authors: Wahyono Y , Nofanda T T , Budiyanto I , Nugroho H , Rosyad M S , Halim M A R , Riski I , Amilia A , Rahmawati D F , Nurauliyaa A H , Baihaqi R A , Syafira F , Lestari P 
Published: July 2021

Abstract
Coastal residents have difficulty in fulfilling the needs of clean water due to tidal water and tidal water intrusion. Meanwhile, clean water is a crucial component in carrying out activities of daily life. This initiative aims to provide an alternative solution in the form of technology to treat water polluted by saline water into clean water. This initiative used the method of electrolysis, filtration, and ozonation. Electrolysis has functions to remove salt contained and reduce levels of heavy metals while filtration functions to filter out the impurities in the form of solid particles, and ozonation takes a role to kill bacteria. Moreover, the target output of this work is the creation of a prototype by using this technology as a technology that can treat water polluted by saline water into clean water. The parameters assessed from this initiative are physical, chemical, and biological parameters of clean water. The results of the total test of dissolved solids of water before processing were 7130 ppm while it was 2490 ppm after getting treatment. The decreasing total value of dissolved solids is 65.077%, which indicates that the test was successful. The result of an electrical conductivity test of water before processing is 310 mA while after processing is 88.6 mA. The decrease in the current value of 71.419% indicates that the test was successful. The results of the turbidity test of water before processing are 0 FAU while after getting treatment is 0 FAU. The turbidity value remains 0, which indicates the test was successful. The results of the pH test of water before processing were 5.7 while the result after treatment got 6.1. The increase in pH value towards pH 7 (neutral) indicates that the test was successful. The test results of salt and heavy metals (Fe, Cu, Cl, Na, and Pb) of water before processing were 0.073 ppm, 0.07 ppm, 0.17 ppm, 0.04 ppm, and 4.24 ppm while after processing was 0 ppm, 0 ppm, 0.07 ppm, 0.03 ppm, and 1.36 ppm. There was a decrease in Fe 100%, Cu 100%, Cl 58,823%, Na 25%, and Pb 67,924% which showed that the test was successful. Test results for fecal coliform and nonfecal coliform bacteria before processing were 43 MPN / 100 ml and 7 MPN / 100 ml while after processing was 23 MPN / 100 ml and 4 MPN / 100 ml. There was a decrease in the value of fecal coliform bacteria 46.511% and nonfecal coliform 42.857% which showed that the test was successful. The use of electrodes needs to be replaced periodically so that the results of clean water production remain optimal.
The influence of polyethelene glycol concentration on silica xerogel synthesis from geothermal sludge to Pb(II) ions adsorption
Authors: Pardoyo  , Azmiyawati C , Ningsih S , Suhartana  , Djunaidi M C 
Published: July 2021

Abstract
Geothermal solid waste contains around 80-95% of silica, which can be used for getting valuable materials. Synthetic silica can be produced from sodium silicate with polyethylene glycol (PEG) as a capping agent. The purpose of this research is to obtain silica xerogel from geothermal sludge, determine the effect of concentration variations of PEG to particle size and Si-OH/Si-O-Si groups ratio of silica xerogel on the adsorption ability to Pb (II) ions. The sol-gel method was applied to synthesize the product. The xerogel successfully resulted in deriving from geothermal solid waste with the addition of PEG. FTIR spectra indicated the presence of Si-OH stretching vibration at 954 cm−1 and Si-O-Si asymmetry stretching vibrations at 1089 cm−1. PSA data showed that silica gel with 0%, 2%, 4%, and 5% were 46.63; 197.01; 468.35; and 569.07 µm, respectively, and increase in particles size and the group’ ratio of Si-OH to Si-O-Si. The addition gel with a variation of PEG 2% slightly increased the Pb(II) ions adsorption capacity at various concentrations of 80 mg/L.
Encapsulation of bromelain in alginate-carboxymethyl cellulose microspheres as an antiplatelet agent
Authors: Wijayanti L , Setiasih S , Hudiyono S 
Published: July 2021

Abstract
Bromelain isolated from pineapple (Ananas comosus) can be an excellent phytotherapeutic agent for cardiovascular treatment as it can inhibit platelet aggregation. However, if it is used orally, it can be easily degraded in an acidic pH environment due to enzymes secreted during the digestion process. Its instability under a certain condition will reduce its pharmacological activity and, as a result, will reduce its health benefit. Therefore bromelain needs to be encapsulated in a matrix such as alginate-carboxymethyl cellulose (CMC) microsphere cross-linked to Ca2+ ion, which will act as a carrier agent. In this research, bromelain encapsulation is done by in situ encapsulation. Particle size analyzer (PSA), Fourier transform infrared spectrophotometer, and scanning electron microscope are used as characterization instruments to investigate the encapsulation of bromelain into the alginate-CMC microsphere. PSA analysis showed that the molecular size of the alginate-CMC microspheres was in the 496.05±2.72 and 629.65±8.70 nm. Encapsulation study using the Bradford method showed that the highest encapsulation ratio was achieved at alginate-CMC ratio of 1.5:0.5 (% w/v:% w/v). These results demonstrated that the alginate-CMC microsphere had potential to be an effective matrix for bromelain encapsulation.
Performance evaluation of 2-C-470 compressor of gas recycle process at PT. Lotte Chemical Titan Nusantara
Authors: Silviana S , Siregar A , Mutaqqin I , Dikrama R M 
Published: July 2021

Abstract
Recycle compressor used at PT. Lotte Chemical Titan Nusantara utilizes a four-stage piston compressor type. The compressor increases the gas pressure from the S-425 degasser at 0.3 bar to the R-400 reactor with a pressure of 22 bars. Evaluation of a compressor performance encompasses assessment over a number of aspects such as the capacity and volumetric efficiency of each stage, mechanical efficiency, compressor power, and cost saving. Performance analysis on the C-470 compressor implied a decrease in a performance marked by a decrease in mechanical efficiency from the design at 96.43% to the actual condition at 79.72%, along with the decrease in volumetric efficiency from the initial design to the actual efficiency for each stage. The differences occurred due to the changes in pressure and temperature of the input and output fluid at each stage. However, the compressor still appropriates to save the cost up to 99.7% with actual efficiency of 79.72%.
Synthesis of Cu2O from modified Fehling reaction for the preparation of Cu2O thin film photocathode by using the spin coating method, characterization, and its photoelectrochemical properties
Authors: Sulat  , Gunawan  , Lusiana R A , Haris A , Widodo D S 
Published: July 2021

Abstract
Hydrogen energy has the potency as a renewable energy source to replace the fossil energy. It can be obtained through the process of photoelectrochemical (PEC) water splitting with the help of a semiconductor as a photocathode to capture photon energy. One of the copper-based metal oxide semiconductors that can be used in the water splitting process is copper(I) oxide (Cu2O), because it has non-toxic advantage, requires an easy synthesis process, low production cost, and has a low band gap (2-2.45 eV). This study aims to determine the effect of Fehling’s modification using citrate in Cu2O synthesis as material to prepare Cu2O thin film photocathode using spin-coating method. The prepared photocathode consists of three stages, namely variations of Cu2O synthesis with mole ratios of copper:citrate of 1:1; 1:2; 1:4, thin film preparation and heating. Then the obtained thin film was characterized using SEM, EDX and XRD. J-V curves of the photocathodes gave current densities, onset potential and applied bias to photon efficiency (ABPE) for Cu2O thin film photocathode prepared by copper:citrate mole ratios of 1:1; 1:2; 1:4 namely 0.09; 0.18; 0.12 mA/cm2 at potential of 0.2 V (vs. RHE), 0.04; 0.08; 0.02 V (vs. RHE), and 0.062, 0.057, 0.058 %, respectively. SEM analysis result showed a spherical morphology of Cu2O. EDX analysis showed that the sample contained copper and oxygen with 78% Cu and 22% O. XRD analysis results showed the presence of Cu2O with an average crystal grain size of 38.08 nm.
Dark matter and dark energy: cosmology of spacetime with surface tension
Authors: Perko H A 
Published: July 2021

Abstract
A mechanical model was introduced at a prior conference for describing spacetime with surface tension, it was shown that continuum wave mechanics governing micro-perturbations of spacetime itself provide an alternate geometric formulation for quantum mechanics. At a second conference, the model was extended to include gravity. In this presentation, the surface tension model of spacetime is applied to cosmology. It is shown that the model can be arranged to exhibit components resembling dark matter and dark energy.
The dark matter component of the model is used to predict stellar velocity and compared with rotation curves for 15 galaxies. By adjusting mass-to-light ratios to best-fit predicted rotational velocity at extreme distances, the model is shown to also match the initial slope and overall shape of measured rotation curves. Mass-to-light ratios from this approach are much lower than previously thought. Total luminosities of the subject galaxies are shown to be proportionate to the square of their best-fit galactic masses. When this proportion is reinserted into the model, the Tully-Fisher relation is derived.
Dark energy components of the model are applied to describe universal expansion. A non-linear Hubble-Lemaitre function is found with asymptotic separation velocity of 3c thereby matching observations. Dark matter and dark energy are postulated to be the cosmological manifestations of surface tension of spacetime.
Can particle appearance or disappearance be described by a quantum mechanical theory?
Authors: Fanchi John R. 
Published: July 2021

Abstract
A common justification for replacing quantum mechanics with quantum field theory (QFT) is that the appearance or disappearance of particles cannot be described using quantum mechanics. We show that this justification for QFT is not generally true by presenting a counterexample: parametrized relativistic quantum mechanics (pRQM). We begin by outlining a pioneering formulation of QFT that includes an invariant evolution parameter. The introduction of an invariant evolution parameter helped guide the development of QFT and is a characteristic feature of pRQM. We then present a probabilistic formulation of pRQM that highlights features of the theory that make it suitable for modelling particle stability. Two examples of particle stability are then presented within the context of pRQM to show that a quantum mechanical theory can be applied to particle stability. The examples considered in this paper are exponential particle decay and neutrino oscillations.
A new approach to the evolving 4+1 spacetime metric
Authors: Land Martin 
Published: July 2021

Abstract
We recently proposed [1, 2] field equations that prescribe a metric gαβ
(x, τ) that is local in the spacetime coordinates x and evolves with the external “worldtime” τ of the Stueckelberg Horwitz Piron (SHP) framework. As in SHP electrodynamics, these field equations exhibit a formal 5D symmetry (α,β = 0, 1, 2, 3, 5), that is strategically broken to 4+1 representations of the Lorentz group. The resulting canonical formalism for this metric embodies a natural foliation of a 5D pseudo-manifold (encompassing both geometry and dynamics) into the τ-parameterized 4D spacetime posed in SHP theory. In this paper, we consider the linearized equations for weak gravitation in this 4+1 formalism, leading to a more straightforward and intuitive derivation of the coupled first-order evolution equations for the metric.
Electric and magnetic fields as explicitly observer dependent four-dimensional vectors and their Lorentz transformations according to Minkowski - Ivezić
Authors: Ivezić Tomislav 
Published: July 2021

Abstract
In this paper a geometric approach to the special relativity (SR) is used that is called the “invariant special relativity” (ISR). In the ISR it is considered that in the four-dimensional (4D) spacetime physical laws are geometric, coordinate-free relationships between the 4D geometric, coordinate-free quantities. It is mathematically proved that in the ISR the electric and magnetic fields are properly defined vectors on the 4D spacetime. According to the first proof the dimension of a vector field is mathematically determined by the dimension of its domain. Since the electric and magnetic fields are defined on the 4D spacetime they are properly defined 4D vectors, the 4D geometric quantities (GQs). As shown in an axiomatic geometric formulation of electromagnetism with only one axiom, the field equation for the bivector field F [33], the primary quantity for the whole electromagnetism is the bivector field F. The electric and magnetic fields 4D vectors E and B are determined in a mathematically correct way in terms of F and the 4D velocity vector v of the observer who measures E and B fields. Furthermore, the proofs are presented that under the mathematically correct Lorentz transformations, which are first derived by Minkowski and reinvented and generalized in terms of 4D GQs, e.g., in [23], the electric field 4D vector transforms as any other 4D vector transforms, i.e., again to the electric field 4D vector; there is no mixing with the magnetic field 4D vector B, as in the usual transformations (UT) of the 3D fields. Different derivations of these UT of the 3D fields are discussed and objected from the ISR viewpoint. The electromagnetic field of a point charge in uniform motion is considered and it is explicitly shown that 1) the primary quantity is the bivector F and 2) that the observer dependent 4D vectors E and B correctly describe both the electric and magnetic fields for all relatively moving inertial observers and for all bases chosen by them. This formulation with the 4D GQs is in a true agreement, independent of the chosen inertial reference frame and of the chosen system of coordinates in it, with experiments in electromagnetism, e.g., the motional emf. It is shown that the theory with the 4D fields is always in agreement with the principle of relativity, whereas it is not the case with the usual approach with the 3D quantities and their UT.
The quaternionic description of quantum mechanics
Authors: Sidharth B.G. 
Published: July 2021

Abstract
It was pointed out by Ezra Newman in the sixties that an imaginary shift of the coordinate in purely classical equations leads to the purely quantum mechanical gyromagnetic ratio g = 2. Newman puzzled about it for decades and finally could not explain this enigmatic finding. The author, Dr. B G Sidharth, Director, B M Birla Science Centre, Hyderabad, has been working on this for a few decades and has concluded the following: 1. The explanation lies at very small scales where the square of the Compton scale is retained and 2. When a complex coordinate is generalized to three dimensions, as Sachs had pointed out we end up with a four dimensional space, which moreover has a Minkowski invariant thrown in. On a further analysis the author noted that in this quaternionic description the spacetime is rather different to the simple Minkowski spacetime. To put it pictorially the former resembles the curly spiral binding while the latter is more like the smooth paper. The author also concluded that this was the reason why despite a century of efforts Einstein’s gravitation could not be reconciled with particle physics. Moving on we consider the second order representation of the quaternions in terms of the 2 × 2 Pauli matrices. This time the line element will be given by σ(i)xi. We get again an invariant but unlike in the 4 × 4 matrix consideration, this time there is no invariance under the reflection symmetry. We consider the different situations like neutrinos, noncommutative geometry and two dimensional surfaces like graphene where this latter case applies.
On periodic motions of a body with an internal moving mass on a rough horizontal plane in the case of anisotropic friction
Authors: Bardin Boris S , Rachkov Alexey A 
Published: July 2021

Abstract
We consider a mechanical system consisting of a body moving on a horizontal plane and a mobile internal mass, which moves in a circle with a constant velocity. Dry anis ot ropic friction force acts between the body and the plane. The body moves without jumping. Five periodic modes of motion are established and conditions of their existence are found. A qualitative analysis of each periodic modes has been performed. In the plane of parameters the domains corresponding to the above periodic modes are determined.
On bifurcations and stability of central configurations in the planar circular restricted four-body problem
Authors: Bardin B S , Volkov E V 
Published: July 2021

Abstract
The restricted four-body problem is considered. That is, we consider motion of an infinitely small body (particle) under the Newtonian gravitational attraction of three bodies (primaries). It is assumed that the primaries move in circular orbits, forming a stable equilateral Lagrange triangle. It is supposed that four bodies move in a plane. There exist relative equilibriums of the particle in the rotating with the primaries coordinate system. In such an equilibrium the particle forms a central configuration with the primaries. In the case of small mass ofa primary the bifurcations ofthe central configurations are investigated, as well as conditions oflinear stability for the central configurations is obtained. The study is performed analytically by using small parameter method.
Analytical and numerical study of the autobalancing process of a dynamically unbalanced rigid rotor fixed in orthotropic viscoelastic supports
Authors: Bykov V G , Kovachev A S 
Published: July 2021

Abstract
A dynamically unbalanced rotor in viscoelastic orthotropic supports equipped with a two-plane automatic ball balancer (ABB) is considered. Based on an analysis of the equations describing the stationary modes of motion of the system, the possibility of the existence of the balanced mode is shown and the necessary conditions for its existence are found. Critical rotor speeds are found for a case of a rotor without an ABB. Amplitude-frequency responses for rotors in isotropic and orthotropic supports are constructed. Autobalancing process for the cases of rotation at constant angular velocity and constant angular acceleration is investigated.
Wave metamorphism of ice
Authors: Epifanov V P , Sazonov K E 
Published: July 2021

Abstract
The paper gives the experimental data on wave metamorphism of ice. The conclusion about the presence of wave metamorphism relies on the local hardness study of model ice sheet. Measurement results were used to obtain characteristic wave lengths. The presence of wave structures has been confirmed by independent tests with indentor, as well as by local hardness studies of full-scale river ice.
Precipitation regions of high energy electrons, injected by a point source moving along an elliptic near-Earth orbit on the Earth surface
Authors: Kolesnikov E K , Klyushnikov G N 
Published: July 2021

Abstract
The paper is devoted to the study of precipitation regions of high-energy electrons injected by a point source moving in near-Earth space along an elliptical orbit. The precipitation regions are constructed on the basis of numerical integration of an ordinary differential equations describing the motion of electrons in a dipole magnetic field. The influence of some parameters of the source orbit on the structure of precipitation regions is considered. They are eccentricity, focal parameter, incline angle to the selected axis in the plane of the geographic equator and the energy of injected electrons. The difference between the obtained regions and the precipitation regions formed for the motion of a point source along circular near-Earth orbit is discussed.
Generalized model for state-resolved chemical reaction rate coefficients in high-temperature air
Authors: Kustova E , Savelev A 
Published: July 2021

Abstract
In the present study, we propose a general model for state-resolved reaction rate coefficients. The model combines the main advantages of several theoretical models for preferential dissociation and exchange reactions coupled to vibrational relaxation. Vibrational and electronic excitation of all species participating in the reaction is taken into account. The complete set of parameters for state-resolved chemical reactions in five-component air is obtained by fitting the results of the most reliable quasi-classical trajectory simulations in the temperature range 2000–15000 K.
A multiplicity of regimes of transonic flow in channels with branching
Authors: Ryabinin A N 
Published: July 2021

Abstract
The flow in 2D channel with a flat plate located along the plane of symmetry of the channel at a certain distance from the inlet was numerically studied. Straight segments formed the channel walls. At the inlet and the outlet of the channel, a supersonic flow was set. The first and third parts of the channel diverged. The middle part converged. Solutions to the Euler equations were obtained using the Ansys CFX finite volume solver. Four solutions were found that differed in the position of the shock waves. The hysteresis in the shock wave position versus Mach number given at the inlet was found. In a certain range of the inlet Mach number, there were asymmetric solutions of the equations.
Shock-wave structures of prospective combined jet engine
Authors: Savelova K E , Alekseeva M M , Matveev S A , Chernyshov M V 
Published: July 2021

Abstract
The paper presents numerical analysis of typical model flows with Mach reflection. For example, flows in narrowing channels between two triangles and long narrowing channels are discussed. The obtained results can serve as reference data for various approximate theoretical models, in particular, for a newly proposed approximate analytical model, which should take into account combustion and detonation.