bluuebunny/crossref_metadata_2025 huggingface dataset:
Primitive function of the Dunford integral
Authors: Aziz A , Solikhin  , Sumanto Y D , Heri R S U
Published: July 2021

In this paper, Dunford integrals and their primitive functions are discussed. We discuss its properties related to absolutely continuous, strictly absolutely continuous, bounded variation function, strictly bounded variation function and their generalizations. The result is obtained that for each function which integrated Dunford, then the primitive function is a continuous, absolutely continuous, and bounded variation function. Furthermore, its generalized absolutely continuous and generalized bounded variation function.
Optimal decision under fuzzy uncertainty for order allocation planning with uncertain parameters: single period case
Authors: Widowati W , Sutrisno  , Tjahjana R H
Published: July 2021

Inventory management on manufacturer and retail industries is commonly containing some uncertain parameters like future cost and future demand value where the decision-maker has to execute the optimal decision under these parameter’s uncertainty. While the data is available then these uncertain parameters can be assigned as a random variable and a probabilistic approach can be used to solve. But, if there is no data available for these uncertain parameters, then a fuzzy uncertainty approach can be used to solve this problem that is discussed in this paper. We have developed a mathematical model that can be used to calculate the optimal decision under fuzzy uncertainty where the decision is calculated and executed before the uncertain parameters are revealed. Numerical experiment results show that the problem was solved by using the proposed mathematical model, the optimal decision was achieved i.e. the optimal procurement volume product type and the optimal stored product volume in the inventory.
Mathematical modeling and analysis of COVID-19 transmission dynamics in Central Java Province, Indonesia
Authors: Fitriani U A , Widowati  , Sutimin  , Sasongko P S
Published: July 2021

Covid-19 is currently a pandemic that is considered as the biggest global threat that classified as the human-to-human transmissionable disease. This pandemic has affected practically all world countries. The aim of this paper is to construct a mathematical model for the spread of the Covid-19 outbreak and analyze its stability. The proposed mathematical model is STQIR (Susceptible, Traced, Quarantine, Infectious, Recovered) model. The form of the model is a nonlinear differential system with five variables. The step of the method i.e., compute the variables positifity, boundedness of solutions, and the basic reproduction number that computed using next generation matrix. Then the basic reproduction number will be used for testing the local stability of the disease free equilibrium using Routh Hurwitz criteria to examine its epidemiological relevance. This work also investigate the sensivity of the model with respect to the variation of each one of its parameters and is tested in application to the recent data on Covid-19 outbreak in Central Java Province, Indonesia.
Study of factors caused diabetes mellitus and stroke diseases toward gender
Authors: Sudarno  , Widiharih T
Published: July 2021

Gender consists of female and male. Diabetes mellitus is a chronic disease characterized by high levels of sugar in the blood. Glucose is controlled by the hormone insulin which is produced by the pancreas. In diabetics, the pancreas is unable to produce insulin according to the body’s needs. Blood sugar tests can be done to find out someone has diabetes. This method by a time blood sugar test and fasting blood sugar test. Stroke is a condition that occurs when the blood supply to the brain is interrupted or reduced due to a blockage (ischemic stroke) or rupture of a blood vessel (hemorrhagic stroke). We can use the proportional hazards regression and the stratified proportional hazards model to determine the factors causing diabetes mellitus and stroke. The significant covariate could be seen as a factor causing disease. Significant covariate also yields hazard ratio. If the event time assumed has loglogistics distribution. Some of the functions discussed in this paper, namely the cumulative distribution function, survival function, hazard rate function, and cumulative hazard function. These functions are useful for prediction tools provided the event time is known. The purpose of this study was to find the factors that cause diabetes mellitus and stroke in the gender strata and making functions of random variables with the logistic distribution. The results obtained from this study are the factors that influence a person at risk of stroke namely the type of stroke, hypertension, systolic blood pressure, diastolic blood pressure, and diabetes mellitus. The factors that affect a person at risk of stroke according to gender are the type of stroke, hypertension, systolic blood pressure. If the sample includes all women who have had a stroke, it is primarily affected by the type of stroke. If the sample consists of all men who have had a stroke, it is concluded that the significant covariates are type of stroke, hypertension, systolic blood pressure, and diabetes mellitus. Men have a higher rate of stroke than women.
Graphical interface of geographically weighted negative binomial regression (GWNBR) model using R-Shiny
Authors: Yasin H , Suryani I , Kartikasari P
Published: July 2021

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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.
Structure of turbulent natural convection in a heated rapidly rotating inter-disk cavity with near-axis heat sinks
Authors: Smirnov Sergei , Smirnov Evgueni , Kolesnik Elizaveta
Published: July 2021

The paper presents the results of implicit LES numerical analysis of natural convection developing in a rapidly rotating inter-disk cavity with the width-to-radius aspect ratio equal to 0.13. The convection under study is developed under conditions of a prescribed temperature distribution over the disk surfaces and heat removing action of two near-axis volume sinks of a proper intensity. The thermal conditions are defined on the base of experimental data available in the literature for the prototype case of mixed-convection flow in a cavity heated from the side of the disk surfaces with axial throughflow of cooling air. The computations were carried out for the Ekman layer equal to 0.28· 10−4, if evaluated with the cavity width. Using the closed-cavity model with near-axis heat sinks, principal features of the flow structure and heat transfer, revealed previously for the prototype case of mixed convection have been reproduced successfully, including formation of a pair of global cyclonic/anticyclone vortices and a cold flow core of nearly constant temperature. It is shown also that each near-disk shear layer can be subdivided into a relatively thin highly gradient “internal” Ekman-type layer and a much thicker “outer” layer, which thickness is of the same order as the thermal layer thickness. For the case considered, groups of elongated regular structures occur within the outer layer that can be detected by analyzing the low-speed fluid motion in the axial direction. Further studies are needed to reveal physical reasons of occurring these structures.
Influence of propeller diameter mounted at wingtip of high aspect ratio wing on aerodynamic performance
Authors: Vinogradov O N , Kornushenko A V , Pavlenko O V , Petrov A V , Pigusov E A , Ngoc Trinh Thang
Published: July 2021

In this paper, the propeller diameter effect on cruising characteristics of a solar-powered aircraft with a high aspect ratio wing is considered. Numerical studies were performed using a program based on the Reynolds-averaged Navier-Stokes equations for Mach numbers M=0.145 and Reynolds numbers Re = 0·3-106. Three aircraft configurations were considered: without propellers, with running two-bladed propellers with diameters of 0.22 m and 0.33 m. Numerical studies showed that the installed propeller introduces significant non-linearity into the lift curves and propeller thrust coefficient versus angle of attack curves. The propeller slipstream velocity field changes depending on the propeller advance ratio and the flow velocity, thus influencing the pressure distribution on the wing and the aircraft aerodynamic performance.
Mathematical model of the charging of thin aluminum film in the space plasma
Authors: Yakovlev A B
Published: July 2021

In this paper the generalization of model of a film charging which takes into account its bilateral form and partial permeability is made. Also the system of the equations for the determination of the density of the charge induced on the film surfaces is obtained and results of calculations of the charge density in plasma of a solar wind and in the radiation belt for different reflection factors of sunlight are given.
Generalized Chebyshev problem in nonholonomic mechanics and control theory
Authors: Yushkov M P , Soltakhanov Sh Kh , Dodonov V V
Published: July 2021

The paper is based on the talk with the same name given at the International scientific conference on mechanics “The Ninth Polyakhov’s Reading” dedicated to the 200th anniversary of the birth of the prominent Russian scientist Pafnuty Lvovich Chebyshev. The generalized Chebyshev problem is formulated, in which the motion of a system in the presence of given generalized forces should satisfy an additional system of linear differential equations in which the order of each equation exceeds three. These problems constitute a new class of control problems in which the motion program is given in the form of the above additional system of differential equations. These equations can be considered as linear nonholonomic constraints of high order, whose reactions are the desired control forces. To solve such problems, two theories were developed at the Department of Theoretical and Applied Mechanics of St. Petersburg University. In the first theory, we construct a consistent system of differential equations for the generalized coordinates and the Lagrange multipliers, which are considered as equitable unknown functions of time. The second theory is based on the generalized Gauss principle. The application of the theory is illustrated by the solution of a real space mechanics problem about the motion of an Earth satellite after fixing the value of its acceleration at some point in time. Especially efficient is the application of the second theory to the determination of the optimal control force for transferring a mechanical system with a finite number of degrees of freedom from an existing phase state to a new specified state within a specified period of time. The new method is used to solve the model problem of controlled horizontal motion of a cart bearing the axes of several mathematical pendulums. It is shown that the use of the generalized Gauss principle for solving this problem is undoubtedly superior to that of the classical Pontryagin maximum principle.
Long-term crop rotation diversification enhances maize drought resistance through soil organic matter
Authors: Renwick Leah L R , Deen William , Silva Lucas , Gilbert Matthew E , Maxwell Toby , Bowles Timothy M , Gaudin Amélie C M
Published: July 2021

Climate change adaptation requires building agricultural system resilience to warmer, drier climates. Increasing temporal plant diversity through crop rotation diversification increases yields of some crops under drought, but its potential to enhance crop drought resistance and the underlying mechanisms remain unclear. We conducted a drought manipulation experiment using rainout shelters embedded within a 36-year crop rotation diversity and no-till experiment in a temperate climate and measured a suite of soil and crop developmental and eco-physiological traits in the field and laboratory. We show that diversifying maize-soybean rotations with small grain cereals and cover crops mitigated maize water stress at the leaf and canopy scales and reduced yield losses to drought by 17.1 ± 6.1%, while no-till did not affect maize drought resistance. Path analysis showed a strong correlation between soil organic matter and lower maize water stress despite no significant differences in soil organic matter between rotations or tillage treatments. This positive relationship between soil organic matter and maize water status was not mediated by higher soil water retention or infiltration as often hypothesized, nor differential depth of root water uptake as measured with stable isotopes, suggesting that other mechanisms are at play. Crop rotation diversification is an underappreciated drought management tool to adapt crop production to climate change through managing for soil organic matter.
Utilization of alternative ingredients as combination feed on the growth of catfish (Clarias sp.)
Authors: Mukti RC , Amin M , Yulisman
Published: July 2021

This study aims to determine the effect of using alternative ingredients as a combination feed on the growth of catfish. This research was conducted in October - November 2020 which took place at the Laboratory of the Experimental Pond of the Departemen of Aquaculture, Sriwijaya University. The test fish used were catfish seeds measuring 5 - 6 cm. The study was designed with an experimental method in the form of a completely randomized design (CRD). The treatment to be used is a combination of commercial feed with alternative feed as many as 5 treatments with 3 replications, P0: commercial feed 100%, P1: combination of commercial feed 25% and alternative feed 75%, P2: combination of commercial feed 50% and alternative feed 50%, P3: combination of 75% commercial feed and alternative feed 25%, and P4: alternative feed 100%. Based on the results obtained, it shows that the use of alternative feed as a combination of feed has no significant effect on growth, feed efficiency and survival of catfish. The use of alternative feed as a combination feed of 50% (P2) has an effect on the growth and feed efficiency which is high in catfish of catfish. The growth of absolute length, absolute weight, and efficiency of fish feed produced were 1.67 cm, 4.20 grams, and 53.25%.
Isolation and Performance Testing of Bacillus subtilis As Biological Agents to Control the Diplodia Disease on Siam Citrus
Authors: Aprilia Dinda , Miftakhurohmat Agus , Sutarman
Published: July 2021

This study aims to determine the feasibility of the Bacillus subtilis isolate as a biological agent and the concentration of bacterial cells capable of controlling Diplodia in the Siamese citrus (Citrus nobilis). Isolation and biological agency testing on soil samples taken from horticultural land were carried out at the UMSIDA Microbiology Laboratory. The trial of the biological agency application was carried out in Talok Village, Dlanggu District, Mojokerto Regency. The application experiment was carried out in a randomized block design, with treatment in the form of bacterial cell concentrations in the application volume consisting of no biological agents, 10−7, 10−8, and 10−9 CFU.ml−1 in 100 ml. The experiment was repeated five times in order to obtain 20 experimental units. The experimental data were analyzed by ANOVA at 5% followed by the 5% HSD test. The results showed that the bacterial isolates of B. subtilis were found to be potential biological agents with the white rhizoid-shaped colony and dry surface, gram-positive, and non-pathogenic in nature. Biological agent B. subtilis with a cell concentration of 10−8 CFU.ml−1 in 100 ml of application solution gave the best effect to reduce the intensity of Diplodia disease in C. nobilis.
The correlation between mangrove ecosystem with shoreline change in Indramayu coast
Authors: Nur Sofyan Hasanuddin , Hilmi Endang
Published: July 2021

Mangrove ecosystem in Indramayu coast has function to preserve coastal area from abrasion and sedimentation as destructive hazard, because mangrove has ability to reduce impact of abrasion and sedimentation in coastal ecosystem. Before 2018, Indramayu regency had shore line coast until 115.5 km, but abrasion caused the degradation of shore line in Indramayu coast until more than 20%. This research aimed to analysis correlation between mangrove ecosystem with shoreline change in Indramayu Coast. The research method used vegetation analysis and mapping analysis. The results showed that (1) the degradation mangrove area was shown by mangrove areal 7688,38 ha (1990) to 862.20 ha (2016), (2) the shoreline change had potential abrasion reaches 255,2-277,65 ha and accretion reaches 40,6 – 315,9 ha. (3) the mangrove density reached 40-145 trees ha-1 (diameter >10cm) and 423-2238 trees ha-1 (diameter>4cm). (4) The optimum width of mangrove greenbelt to reduce coastal disaster and shoreline change in Indramayu between 200 – 250 m
Analysis of Overcurrent Safety in Miniature Circuit Breaker AC (Alternating Current) and DC (Direct Current) in Solar Power Generation Systems
Authors: Jamaaluddin Jamaaluddin , Sulistiyowati Indah , Reynanda BWA. , Anshory Izza
Published: July 2021

The sun is a source of energy and has advantages over fossil energy sources. This solar energy really needs to be researched and developed further. The use of solar energy is by installing a Photovoltaic Cell (PV) along with the Solar and Battery Control system. In short, it can be referred to as a Solar Power Plant (PLTS). This PLTS will be used in buildings as the Solar Building System (SBS). Completing this system requires a protection system management. The protection system known to the general public is the use of a Miniature Circuit Breaker (MCB). This MCB is intended for direct current and alternating current. To get a good protection system in PV mini-grid, how to use MCB and how to install it must be chosen. So that you will get a conclusion that the characteristics and level of efficiency are better than the two uses of the MCB.
The Application of Geostatistical Analysis on Radiometric Mapping Data to Recognized the Uranium and Thorium Anomaly in West Sulawesi, Indonesia.
Authors: Gde Sukadana I , Wayan Warmada I , Harijoko Agung , Indrastomo Frederikus Dian , Syaeful Heri
Published: July 2021

Mamuju Region in West Sulawesi, Indonesia is one of prospect area of uranium/thorium in Indonesia. High radiometric concentrations were located in Adang Volcanic Rocks. This formation is grouped as basaltic to intermediate rock and composed by lava, pyroclastic rocks, and tuff. Regional field radiometric mapping, including radiation dose rates, potassium, uranium, and thorium contents of soil and rock was conducted to identify the existence of radioactive minerals and prospect zones. Some radiometric anomalies are detected and probably related to hydrothermal alteration, leaching, and precipitation processes. Uranium anomaly (97,261 ppm) located in Mamuju River upstream, Botteng, Takandeang and Ahu area. The anomaly related to uranium leaching and precipitation processes in leucite basalt lava. Thorium anomaly (369,461 ppm) located in Pangasaan, Takandeang, Ahu, and Taan area. To expand this radiometric mapping, we characterized the reflectance of Landsat-8 imagery based on field measurement data. Based on circular structures identification, uranium/thorium anomaly are related to the existence of volcano vents on Adang Volcanic. Based on band rationing, high uranium contents distributed in the area with less ferromagnesian mineral, while thorium did not affect. These field based and remote sensing characterization results could be used as preliminary parameters to identify wide and detail prospects.
Causes, Dynamics, and Environmental Conflict Resolution Models in Coal-Fired Steam Power Plant Development Locations
Authors: Ishardanti Ria , Herdiansyah Herdis , Seda Francisia Saveria Sika Ery
Published: July 2021

This paper examines the causes, dynamics, and models of environmental conflict resolution that can be applied in the construction of a coal-fired steam power plant. The existence of power plants is a dilemma because it has negative impact to the society and environment that can lead to conflict. Environmental conflicts always begin with ecological degradation which becomes increasingly complex due to social factors. Discussions of environmental conflicts often focus on ecological damage but forget about the social impacts that will result. The causes of conflicts such as competition for natural resources, poor management of natural resources and the environment, and the dynamics of natural resources that cross borders require proper conflict management to deal with them. This study offers management conflicts models in resolving social-environmental conflict.
Social-Ecological Vulnerability and Livelihood Improvement Strategies of Landslide Victims in Pattalikang Village, Gowa Regency in National Security Perspective
Authors: Adri Khairunnisa , Sumantri Siswo Hadi , Triutomo Sugeng , Sari Deffi Ayu Puspito
Published: July 2021

Landslides are caused by natural environmental factors and cultural, environmental factors, such as changes in land use and social conditions. In the event of a landslide disaster in Pattalikang Village, the community had to start over from scratch and improve their livelihoods. This study aims to analyze: (1) the social-ecological vulnerability of landslide in Pattalikang Village; (2) disaster mitigation efforts for the people of Pattalikang Village after landslides; and (3) Strategies for improving the livelihoods of the people of Pattalikang Village after landslides from a national security perspective. This study used a qualitative approach with descriptive-analytical methods. Respondents are from the Pattalikang Village community and representatives from the head of Pattalikang village, the Regional Disaster Management Agency, the Social Service, the Agricultural Service, the Public Works and Housing Agency, and Tagana Gowa Regency. The results showed that: (1) The socio-ecological vulnerability in Pattalikang Village was categorized as vulnerable based on the scoring and weighting of socio-ecological vulnerability factors; (2) Mitigation efforts carried out were planting vetiver in every landslide-prone point and training of disaster risk reduction for community; (3) The strategy used by the communities who are victims of landslides is consolidation and survival strategy as the strength point to rebuild the communities and improving livelihoods after disaster.
Determination of priority locations for the implementation of rice farming insurance: a case study on disaster hazards in Cilacap regency
Authors: Pramukti Unggul , Suryanto  , Gravitiani Evi
Published: July 2021

In 2018, Cilacap Regency produced a total of 793,265 tons of rice, and was the second largest producer of the commodity in Central Java Province, after Grobogan Regency. However, Cilacap is very prone to flooding, thus is grouped into the high flood hazard category. The aim of this study is to determine the rice fields that need to be included in the Rice Farming Business Insurance program. It was conducted using an overlay and weighting or scoring method. The data were the Flood and Drought Hazard Maps obtained from the National Disaster Management Authority (BNPB), and the Rice Field Map obtained from the Geospatial Information Agency (BIG). The results showed that 17,251 ha of the rice farm land were in the priority I category, while 60,742 and 223 ha(s), were in the Priority II and III categories respectively. Furthermore, the sub-district that was most affected by the flood and drought was Kawunganten. In conclusion, the results can be used in the creation of priority policies for the Rice Farmers Business Insurance program
The distillation process of palm sap (Arenga pinnata MERR) to produce bioethanol
Authors: Ansar  , Nazaruddin  , Azis Atri Dewi
Published: July 2021

Aren palm (Arenga pinnata MERR) is a type of palm tree that grows in tropical forests, especially in South and Southeast Asia. There are 3000 species of palm and they are categorized as multipurpose trees because they were used as raw materials for various products, such as brown sugar, palm syrup, palm wine, vinegar, alcohol, and bioethanol. This study aims to examine the distillation process to produce bioethanol from aren palm. The research sample was obtained from local farmers in Sasaot Lombok, Indonesia. The process used to produce bioethanol is multilevel distillation. The raw materials are first fermented using yeast, charcoal, and lime with a variety of compositions. The bioethanol produced is used as a substitute fuel for a 4-stroke motorbike engine. The results showed that the composition of the fermentation mixture of 250 grams of yeast, 100 grams of charcoal, and 100 grams of whiting produced the highest levels of ethanol, namely 93%. This level of ethanol cannot be used in a 4-stroke motorbike engine properly because the motor rotation is unstable.