bluuebunny/crossref_metadata_2025_split huggingface dataset:
Efficiency of Ni Content in Laterite Nickel Deposits through The Least Square Method Approach on Semivariogram
Authors: Usman F , Tinungki G M , Herdiani E T 
Published: December 2021

Abstract
Ordinary kriging is one of the geostatistical techniques used for spatial prediction on a spatially distributed random plane. Ordinary kriging is a linear unbiased estimator which is part of a semivariogram system of equations that minimizes errors of variance in estimating mineral resources. The semivariogram model shows optimal results in the estimation using the least square method, the effective minimization method smoothes the data points against the curve on a semivariogram graph, the least square makes the size error efficient in the semivariogram model and has been proven to be effective in reducing errors in the semivariogram model in the case of laterite nickel deposits. at PT. Vale Indonesia Tbk. Thus, conclusively the prediction of unsampled Ni content results is very accurate. This is indicated by the lowest root mean square error (RMSE) in limonite in the exponential model, saprolite in the spherical model, and bedrock in the gaussian model. The greatest value of Ni content in this study was in the saprolite layer.
Time Series Clustering for Robust Mean-Variance Portfolio Selection: Comparison of Several Dissimilarity Measures
Authors: Gubu La , Rosadi Dedi , Abdurakhman  
Published: December 2021

Abstract
This paper shows how to create a robust portfolio selection with time series clustering by using some dissimilarity measure. Based on such dissimilarity measures, stocks are initially sorted into multiple clusters using the Partitioning Around Medoids (PAM) time series clustering approach. Following clustering, a portfolio is constructed by selecting one stock from each cluster. Stocks having the greatest Sharpe ratio are selected from each cluster. The optimum portfolio is then constructed using the robust Fast Minimum Covariance Determinant (FMCD) and robust S MV portfolio model. When there are a big number of stocks accessible for the portfolio formation process, we can use this approach to quickly generate the optimum portfolio. This approach is also resistant to the presence of any outliers in the data. The Sharpe ratio was used to evaluate the performance of the portfolios that were created. The daily closing price of stocks listed on the Indonesia Stock Exchange, which are included in the LQ-45 indexed from August 2017 to July 2018, was utilized as a case study. Empirical study revealed that portfolios constructed using PAM time series clustering with autocorrelation dissimilarity and a robust FMCD MV portfolio model outperformed portfolios created using other approaches.
Rainfall Data Modeling with Artificial Neural Networks Approach
Authors: Astutik S , Pramoedyo H , Rahmi N S , Irsandy D , Damayanti R H P Y 
Published: December 2021

AbstractRainfall is one of the important information that widely used in various fields. Rainfall data involving location information is referred to as spatial rainfall data. Some of the model approaches to spatial rainfall data are the Vector Autoregressive (VAR) model, state-space, Markov chain stochastic model, and Geographically Weighted Regression (GWR). However, these models have not been able to produce predictions of the occurrence of no rain (zero value) or extreme values. Currently, theoretical modelling is mostly approached by artificial neural network (ANN) techniques. The purpose of this study is to model spatial rainfall data in East Java, Indonesia in 2020 with the ANN approach which is supported by several variables such as location and elevation information. The ANN used backpropagation and Rporp by combining the learning rate and layer which is then obtained the RMSE value. The results show that the best model has the smallest RMSE of 1.22 when the learning rate is 0.15 on 11 layers using Rprop algorithm.
Vector Autoregressive-Based Maximum MCUSUM Control Chart for Monitoring the Quality of White Crystal Sugar
Authors: Khusna H , Mashuri M , Wibawati  
Published: December 2021

Abstract
The white crystal sugar which is widely consumed sugar has two critical to qualities, namely the index of solution colour and the level of sulphur dioxide. These quality characteristics have small mean and variability shifts, as well as autocorrelation pattern. This research aims to propose residual-based Maximum Multivariate Cumulative Sum (Max-MCUSUM) control chart, one of the single control charts to monitor small shifts of mean and variability simultaneously, for monitoring the quality of white crystal sugar. The vector autoregressive (VAR) model is utilized to model the daily solution colour index and the daily sulphur dioxide level, then the residuals are monitored using Max-MCUSUM chart. The VAR-based Max-MCUSUM chart employs bootstrap, one of the nonparametric resampling methods, to estimate the control limit. The results of white crystal sugar quality control show that the processes in the last week of August 2020 need to be improved. Monitoring the white crystal sugar data using conventional control chart leads to many false alarm signals. Furthermore, the proposed control chart is more sensitive than the residual-based MEWMA and residual-based Hotelling’s T
2 charts in case of monitoring the quality of white crystal sugar.
Technology Integration to teaching mathematics in Higher Education during Coronavirus Pandemic using SAMR Model
Authors: Wijaya Tommy Tanu , Rizki L M , Yunita W , Salamah Umi , Pereira J , Zhang Cheng , Li Xinxin , Purnama A 
Published: December 2021

AbstractTechnology integration is one of the abilities teachers need to support teaching and learning activities and direct students to deep learning. Choosing a learning media based on technology is more difficult in statistics lesson. This study aimed to analysis the ability of teachers in integrating technology during the coronavirus pandemic using the SAMR model. This research used a qualitative method, this research data was in the form of information on what technology was used and how the teacher integrated technology during the coronavirus pandemic. Data was collected by means of observation and interviewing 2 Guangxi Normal University students who took this course. The results showed that the ability of teachers to integrate technology in statistics lesson during coronavirus pandemic was at every SAMR level. This study proves that the coronavirus pandemic has a positive impact on teachers’ ability to integrate technology.
The Impact of Creative Problem-Solving Learning Model Based Android Towards Learning Outcomes of Elementary School Students
Authors: Jusmawati  , Satriawati  , Irman R , Rahman Abdul , Arsyad Nurdin 
Published: December 2021

Abstract
This study aims to know the impact of the Creative Problem Solving learning model based on android on the learning outcomes of elementary school students. The numbers population was all students of SD Tunas Bangsa. The technique of determining the sample used simple random sampling. This research used pre-experimental with One Group Pretest-Posttest Design. Data collection techniques used learning outcomes tests to measure the student’s learning outcomes both before and after being given treatment, documentation, and observations about student learning activities and teacher observations regarding the implementation of the model during the learning process. Descriptive statistical analysis data described the students’ mathematics learning outcomes. Inferential statistical analysis to test the hypothesis using the dependent t-test or Paired-Sample T-Test with SPSS 21.0 version. The results of the research showed that there was an impact of the Creative Problem Solving learning model based on android towards learning outcomes. This is evidenced by the results of the pretest in the less category experienced an increase in posttest learning outcomes in the good category. It can be concluded that there is an the impact of Creative Problem Solving learning model based on android towards learning outcomes of elementary school students.
Studying the surfactant dynamics at non-isothermal liquid surface with thermography
Authors: Mizev A I , Shmyrov A V 
Published: December 2021

Abstract
The dynamics of liquid multiphase systems largely depends on the conditions on the interface. The behavior of a system with adsorbed surfactant layers at the interface boundaries may differ qualitatively from the behavior of a system with pure surface. The experimental study of such systems is difficult, since the presence of adsorbed layer can most often be judged only by indirect signs. Therefore, most of the research is carried out by numerical modeling. Unfortunately, the currently existing numerical studies of liquid multiphase systems with adsorbed surfactant layer are far from perfect due to numerous simplifications and approximations assumed in theoretical models. In this paper, we propose a new approach for visualization and studying the boundary between a clean surface and an adsorbed surfactant layer. It is based on the comparison of track images of the fluid motion in the volume and the registration of the temperature distribution at the interface boundary. This approach made it possible to unambiguously associate the characteristic regions on the temperature profile with the position of the so-called stagnation point. The proposed method for visualizing the stagnation point can be useful in a number of problems of interface hydrodynamics based on the thermocapillary effect.
Image-based processing simulation of shock wave propagation through the area of ionization instability
Authors: Kravchenko O V , Azarova O A , Lapushkina T A 
Published: December 2021

Abstract
A partially automatic method of digital processing images (photographs, shadow and Schlieren pictures) for the analysis of experimental data is proposed. The method is utilized to investigate the effect of the region of ionization instability created by a glow gas discharge on the front of an initially flat shock wave. The proposed method is based on a composition of simple image processing operations and makes it possible to perform simulations taking into account the real geometry of the ionization strata and the shape of the front of a shock wave based on the obtained experimental images. First, as a result of digital processing the geometry of experimental objects is extracted from the images. This information is then embedded in the Navier-Stokes code for conducting simulations. New results for the real geometry of ionization strata of different scales are presented which confirmed the previous ones obtained for the density homogeneously stratified source model.
Polychromatic Hilbert diagnostics of phase and temperature disturbances, induced by candle flame in air
Authors: Arbuzov V A , Arbuzov E V , Dubnishchev Yu N , Zolotukhina O S , Lukashov V V 
Published: December 2021

Abstract
The work is motivated by the scientific and practical significance of the problem of non-disturbing diagnostics of phase and temperature fields induced in a gas medium by a flame of a torch (candle). The spatial conditions in which the fields are studied satisfy the model of axial symmetry of the torch associated with the vertical orientation of the candle. A method adequate to the problem to be solved has been developed, based on polychromatic Hilbert visualization of phase optical density fields, measurement of the temperature profile in selected sections of the medium under study, registration and selection of RAW images recorded by the photomatrix in RGB channels. The visualized Hilbert structures contain information on the phase optical density perturbations induced by the temperature field. The reliability of the results is confirmed by comparing the experimentally obtained hilbertograms and those reconstructed from phase structures using the Abel transform.
Investigation of partially transparent and high-density two-phase liquids using laser interference method
Authors: Kuchmenko A V , Lapitsky K M , Lapitskaya I A , Badamshina E B 
Published: December 2021

Abstract
The purpose of the present work was to investigate partially transparent and high-density two-phase liquids using the laser interference method to establish the limits of applicability of this method. The results of the work include the interference fringe patterns of drops when using various kinds of liquids, the calculated drop sizes. The calculation of inaccuracies was also carried out to further establishing the limits of applicability of this method.
Processing and visualization of the results of parametric numerical calculations
Authors: Bondarev A E , Kuvshinnikov A E 
Published: December 2021

AbstractIn modern problems of mathematical modeling in computational gas dynamics, it is increasingly necessary to implement parametric studies. In these cases, the key factors of the problem under consideration vary with the chosen step within the given ranges. Calculations of this kind can be effectively carried out by constructing a generalized computational experiment. A generalized computational experiment is a computational technology that combines the solution of mathematical modeling problems, parallel technologies, and visual analytics technologies. The results of a generalized computational experiment are multidimensional arrays, where the dimension of the arrays corresponds to the number of key factors. Processing and visual presentation of such arrays requires solving a number of separate tasks. The processing and visual presentation of the results are carried out for target functionals represented as a function of many variables. The report presents an examples of solving specific processing and visualization problems based on the implemented generalized computational experiment for 3D cone in supersonic flow.
Crosscorrelation image processing for surface shape reconstruction using fiducial markers
Authors: Shmatko E V , Pinchukov V V , Bogachev A D , Yu Poroykov A 
Published: December 2021

Abstract
Optical methods for deformations diagnostic and surface shape measurement are widely used in scientific research and industry. Most of these methods are based on triangulating a set of two-dimensional points in the images appropriate to the same three-dimensional points of the object in space. Various algorithms to search such points are applied. The possibility of using cross-correlation processing of digital images to search these points is considered in the work. Algorithms based on the correlation function calculation are widely employed in such a popular flow diagnostic method as PIV. The cameras of a stereo system for surface shape measurement can be widely spaced, and the tilt angles relative to the surface can differ significantly. This leads to the fact that the images taken from the cameras cannot be directly processed by the correlation function because it is not invariant to rotation. To solve this problem, fiducial markers are used to find an initial estimate of displacement of the images relative to each other. This approach makes it possible to successfully apply correlation processing for stereo system images with a large stereo base.
Features of measurements the IR radiation power of a laser diode used in active optoelectronic systems for studying flows
Authors: Bliznyuk V V , Parshin V A , Savinov N S , Selivanov A A , Tarasov A E 
Published: December 2021

Abstract
In active optical-electronic systems for stream research that regulate thermal-physical parameters of diagnosed stream volume, the controlled source of the heat flow can be acquired by radiation of high-power IR laser diodes into the void. In the current work the peculiarities of measurement of this radiation are considered, specified by its strong divergence. It is shown that the measurements can involve laser wattmeters IMO-4M with planar thermoelectric primary measuring transformers of the laser radiation with a flat receiving site provided.
Two-wave laser displacement meter
Authors: Lavrov E A , Mazur M M , Shorin V N , Suddenok Y A 
Published: December 2021

Abstract
A two-wave laser displacement meter based on Michelson interferometer has been developed for measurements at an unknown temperature profile at the measurement trace. The requirements for meteorological parameters support during displacement measurements using the offered laser interferometer are less strict compared to using an one-wave interferometer. The article describes the optical schematic of the device. The results for the measurements of the developed laser interferometer for realization of the displacement unit within the limits of 60 m are presented. The weather condition influence on measurements was estimated. The application of pseudorandom displacement of the interferometer’s reference arm with accumulation made possible the reflector position resolution down to 0.01 μm the stoped-displacement mode, and down to 0.05 μm at the displacement mode. It was shown that such resolution allows to measure displacements at trace up to 60 m with inaccuracies less than 10 μm at the temperature profile amplitude up to 1 °C.
Comprehensive study of boiling regimes with use of high-speed imaging and gradient heatmetry
Authors: Sapozhnikov S Z , Mityakov V Yu , Mityakov A V , Pavlov A V , Bobylev P G , Kikot N E , Bikmulin A V 
Published: December 2021

Abstract
In the study of heat transfer during boiling, optical methods and thermometry are prevailing. The possibilities of experiment are significantly expanded by new technology – gradient heatmetry, in which heterogeneous gradient heat flux sensors with time constant of nanoseconds are used. When studying of boiling of subcooled water in a large volume on the surface of the titanium sphere, preheated up to 300-500 °C, heatmetry was combined with visualization of boiling modes using a high-speed camera Evercam 1000-4-M. It is possible to obtain the distribution of heat flux per unit area along the latitudinal coordinate and to relate the local heat flux per unit area with observed boiling regimes and initial temperatures of water and the model.
Development of optical diagnostic method for colloidal solutions based on elastic light scattering
Authors: Sapronov M V , Skornyakova N M , Usmanova S S 
Published: December 2021

Abstract
The work is devoted to colloidal solutions diagnostics by the optical method based on elastic light scattering by particles of the dispersed phase. The scheme of the developed optical electronic complex for recording the intensity of radiation scattered by colloidal particles is presented. The experimental study results of the elastic scattering of laser radiation on spherical nanometer-sized aluminum oxide particles suspended in water are represented. A method for measuring the scattering indicatrix based on the registration of radiation scattered in various directions and subsequent computer processing has been proposed. A method for reconstructing the particle size distribution function of colloidal solution dispersed phase by comparing the measured scattering indicators and their computer models has been developed. The method has been tested, as a result of which the size distribution function of aluminum oxide nanopowder particles has been restored.
Historical and future runoff changes in the Yangtze River Basin from CMIP6 models constrained by a weighting strategy
Authors: Zhao Jiazhen , He Shengping , Wang Huijun 
Published: December 2021

Abstract
Based on the ERA5-Land datasets from 1981–2020, a decadal oscillation has been found in the variation of summer runoff in the middle and lower reaches of the Yangtze River Basin (MLYRB). The oscillation suggests that the MLYRB will experience increased runoff in the next few decades after 2020, which saw a record high runoff in the MLYRB. The decadal changes in summer runoff over the MLYRB under various climate change scenarios are then analyzed with direct runoff outputs from 28 general circulation models participating in the sixth phase of the Coupled Model Intercomparison Project. Given that the equal-weighted multi-model ensemble mean could not well represent the historical runoff changes in the MLYRB, in this paper we introduce a model weighting scheme that considers both the model skill and independence. It turns out that this scheme well constrains the models to represent the observed decadal changes of summer runoff. The weighted mean projections suggest that the summer runoff in the MLYRB during 2015–2100 under all warming scenarios will be higher than the present day; and 2021–2040 is likely to be a period with significantly increased summer runoff. Results of the present study have great implications for flood control and effective water resources management over the MLYRB in the future, and the weighting approach used in this paper can be applied to a wide range of projections at both regional and global scales.
Global to local impacts on atmospheric CO2from the COVID-19 lockdown, biosphere and weather variabilities
Authors: Zeng Ning , Han Pengfei , Liu Zhiqiang , Liu Di , Oda Tomohiro , Martin Cory , Liu Zhu , Yao Bo , Sun Wanqi , Wang Pucai , Cai Qixiang , Dickerson Russell , Maksyutov Shamil 
Published: December 2021

AbstractThe worldwide lockdown in response to the COVID-19 pandemic in year 2020 led to an economic slowdown and a large reduction in fossil fuel CO2emissions (Le Quéré 2020Nat. Clim. Change10647–53, Liu 2020Nat. Commun.11); however, it is unclear how much it would slow the increasing trend of atmospheric CO2concentration, the main driver of climate change, and whether this impact can be observed considering the large biosphere and weather variabilities. We used a state-of-the-art atmospheric transport model to simulate CO2, and the model was driven by a new daily fossil fuel emissions dataset and hourly biospheric fluxes from a carbon cycle model forced with observed climate variability. Our results show a 0.21 ppm decrease in the atmospheric column CO2anomaly in the Northern Hemisphere latitude band 0–45° N in March 2020, and an average of 0.14 ppm for the period of February–April 2020, which is the largest decrease in the last 10 years. A similar decrease was observed by the carbon observing satellite GOSAT (Yokotaet al2009Sola5160–3). Using model sensitivity experiments, we further found that the COVID and weather variability are the major contributors to this CO2drawdown, and the biosphere showed a small positive anomaly. Measurements at marine boundary layer stations, such as Hawaii, exhibit 1–2 ppm anomalies, mostly due to weather and the biosphere. At the city scale, the on-road CO2enhancement measured in Beijing shows a reduction by 20–30 ppm, which is consistent with the drastically reduced traffic during the COVID lockdown. A stepwise drop of 20 ppm during the city-wide lockdown was observed in the city of Chengdu. The ability of our current carbon monitoring systems in detecting the small and short-lasting COVID signals at different policy relevant scales (country and city) against the background of fossil fuel CO2accumulated over the last two centuries is encouraging. The COVID-19 pandemic is an unintended experiment. Its impact suggests that to keep atmospheric CO2at a climate-safe level will require sustained effort of similar magnitude and improved accuracy, as well as expanded spatiotemporal coverage of our monitoring systems.