bluuebunny/crossref_metadata_2025_split huggingface dataset:
Iterated Laurent series over rings and the Contou-Carrère symbol
Authors: Gorchinskiy S. O. , Osipov D. V. 
Published: January 2021

Abstract
This article contains a survey of a new algebro-geometric approach for working with iterated algebraic loop groups associated with iterated Laurent series over arbitrary commutative rings and its applications to the study of the higher-dimensional Contou-Carrère symbol. In addition to the survey, the article also contains new results related to this symbol.
The higher-dimensional Contou-Carrère symbol arises naturally when one considers deformation of a flag of algebraic subvarieties of an algebraic variety. The non-triviality of the problem is due to the fact that, in the case

, for the group of invertible elements of the algebra of

-iterated Laurent series over a ring, no representation is known in the form of an ind-flat scheme over this ring. Therefore, essentially new algebro-geometric constructions, notions, and methods are required. As an application of the new methods used, a description of continuous homomorphisms between algebras of iterated Laurent series over a ring is given, and an invertibility criterion for such endomorphisms is found. It is shown that the higher- dimensional Contou-Carrère symbol, restricted to algebras over the field of rational numbers, is given by a natural explicit formula, and this symbol extends uniquely to all rings. An explicit formula is also given for the higher-dimensional Contou-Carrère symbol in the case of all rings. The connection with higher-dimensional class field theory is described.
As a new result, it is shown that the higher-dimensional Contou-Carrère symbol has a universal property. Namely, if one fixes a torsion-free ring and considers a flat group scheme over this ring such that any two points of the scheme are contained in an affine open subset, then after restricting to algebras over the fixed ring, all morphisms from the

-iterated algebraic loop group of the Milnor

-group of degree

to the above group scheme factor through the higher-dimensional Contou-Carrère symbol.
Bibliography: 67 titles.
The Dickman–Goncharov distribution
Authors: Molchanov S. A. , Panov V. A. 
Published: January 2021

Abstract
In the 1930s and 40s, one and the same delay differential equation appeared in papers by two mathematicians, Karl Dickman and Vasily Leonidovich Goncharov, who dealt with completely different problems. Dickman investigated the limit value of the number of natural numbers free of large prime factors, while Goncharov examined the asymptotics of the maximum cycle length in decompositions of random permutations. The equation obtained in these papers defines, under a certain initial condition, the density of a probability distribution now called the Dickman–Goncharov distribution (this term was first proposed by Vershik in 1986). Recently, a number of completely new applications of the Dickman–Goncharov distribution have appeared in mathematics (random walks on solvable groups, random graph theory, and so on) and also in biology (models of growth and evolution of unicellular populations), finance (theory of extreme phenomena in finance and insurance), physics (the model of random energy levels), and other fields. Despite the extensive scope of applications of this distribution and of more general but related models, all the mathematical aspects of this topic (for example, infinite divisibility and absolute continuity) are little known even to specialists in limit theorems. The present survey is intended to fill this gap. Both known and new results are given.
Bibliography: 62 titles.
On the reasons of spatial heterogeneity of the plasma chemical composition in ablation controlled discharges
Authors: Pashchina A S 
Published: January 2021

Abstract
The reasons of spatial heterogeneity of the plasma chemical composition in ablation controlled discharges are analyzed. The “locking” of atoms of chemical elements with a low ionization potential in the vicinity of a negatively charged wall due to the backflow of a significant fraction of ionized atoms onto the wall is considered as one of the effective mechanisms of plasma demixing and change of its chemical composition in comparison with the initial stoichiometry of the ablating substance. The proposed approach is consistent with the results of spectroscopic studies of a capillary discharge with an ablating wall (polymethylmethacrylate), during which a significant decrease in the carbon mole fraction with a simultaneous increase in the hydrogen mole fraction in the discharge core was revealed. According to the obtained results, the physical processes leading to the spatial separation of chemical elements occur exactly in the capillary spatial domain. The observed demixing of the plasma jet is manly a consequence of the processes that take place inside the capillary.
Microwave power dissipation in a microwave plasma filament
Authors: Brovkin V G , Vedenin P V , Mashek I Ch 
Published: January 2021

Abstract
A plasma channel (filament) formed in the electromagnetic field of microwave (MW) radiation shows promise for its application for off-body non-electrode modification of a gas flow (plasma aerodynamics) and in the plasma assisted combustion process. In these problems, the channel is considered as an object that converts the energy of electromagnetic radiation into gas heating. To estimate the total power absorbed in the plasma from above, simple formula is obtained. Numerical calculations in air in the pressure range P = 20-100 Torr based on a simplified 2D model using a fairly complete system of plasma-chemical reactions have shown that the total absorbed power is close to its estimate from above when the plasma channel develops.
Stationary layered vector fields and their divergence functions
Authors: Burakhanov B M 
Published: January 2021

Abstract
A scalar – vector approach to the study of general properties of scalar functions and vector fields is formulated. This approach is based on taking into account the general properties of their scalar and vector characteristics, as well as taking into account their invariants. The scalar – vector form of writing layered vector fields and an alternative version of this form of writing are discussed. New invariant characteristics of multidimensional scalar functions are introduced. For the name of these characteristics, it is proposed to use the terms - the Hamilton derivative and the Laplace derivative. A local volume approximation of a scalar function is introduced. It is essential that the nonlinear part of this approximation consists of two qualitatively different components. For the names of these components, it is proposed to use the terms-parabolic component and harmonic component. A factorized form of writing the divergence functions of a stationary layered vector field is obtained.
Simulation of the equilibrium flow of plasma with the addition of hydrocarbons in the scope of graphene synthesis using a DC plasma torch
Authors: Shavelkina M B , Ivanov P P , Bocharov A N 
Published: January 2021

Abstract
Graphene synthesis in the helium and argon plasma jets generated by 40 kW DC plasma torch under the pressure 350 Torr is investigated experimentally and by means of the modeling. Propane-butane mixture and methane are used as the carbon feedstock. Scanning microscopy shows that in the case of helium the structure with lateral size up to 500 nm is being synthesized. In the case of argon the morphology of graphene flakes varies from rumpled to rectified sheets with lateral size up to 2 μm. Temperature and velocity profiles are determined for the helium and argon jets using the numerical simulation. Addition of hydrocarbons into the inert plasma jets creates an environments differing in the composition and the charge concentration.
A blended learning with social media in computer-aided drafting courses
Authors: Nuryanto A , Pardjono  , Ngadiyono Y , Nugraha Y , Rofiq Z 
Published: December 2020

Abstract
This study aimed to determine the effect of the blended learning model with social media on learning outcomes of computer aided drafting (CAD). The method used in this quasi-experimental study was a non-equivalent control group design. The research sample consisted of two groups, namely the control and experimental groups. The experimental group is treated by applying the blended learning model with social media in CAD courses, while the control group uses conventional learning methods. Data collection techniques used were observation, questionnaires, and documentation. The results of this study indicate that the blended learning model in CAD learning can be done face-to-face in the form of lectures, questions and answers, demonstrations and assignments, and online in the form of uploading teaching materials in the form of materials, sample videos, discussion forums, assignments, and assessment. Learning outcomes using the blended learning method with social media increased by 29.2%, and the average value was higher than conventional learning. The blended learning model with social media significantly affects CAD learning outcomes (t=7,06 and Sig. 0,000 <0,05).
Multiple intelligences in welding practice lectures
Authors: Wibowo Y E , Djatmiko R D , Marwanto A 
Published: December 2020

Abstract
This study aims to determine the multiple intelligences possessed by students, the level of multiple intelligences of students and to measure the relationship between multiple intelligences with the learning outcomes of welding practice lectures in the Undergraduate Program of Mechanical Engineering Education, Faculty of Engineering, Yogyakarta State University. The method used is a survey. The research was carried out in the Undergraduate Program of Mechanical Engineering Education, Faculty of Engineering, Yogyakarta State University. The research was conducted from April to July 2020 during the COVID-19 pandemic and was conducted online. The research subjects were students of the 2018 Undergraduate Program of Mechanical Engineering Education, Faculty of Engineering, Yogyakarta State University. The independent variable is the student’s multiple intelligences and the dependent variable is the learning result of welding practice lectures. The result of this research shows that the highest multiple intelligences is interpersonal intelligence (78.91%) and the lowest multiple intelligences is naturalist intelligence (63.48%). Other multiple intelligences include verbal-linguistic intelligence (72.01%), logic-mathematics (72.59%), visual-spatial (71.29%), kinesthetic (72.02%), musical (68.36%), intrapersonal (73.93%) and existential (65.43%). The highest multiple intelligences that became dominant from the students of the S1 Mechanical Engineering Study Program, Faculty of Engineering, Yogyakarta State University, were interpersonal intelligence with 20 students (25.97%), intrapersonal with 17 students (22.08%), visual-spatial with 8 students (10.39%), logic-mathematics with 7 students (9.09%), musical with 7 students (9.09%), verbal-linguistics with 6 students (7.79%), kinesthetic with 5 students (6.49%), existential with 5 students (6.49%) and naturalists with 2 students (2.60%). The value (Sig.) Is 0.028 <0.05 and the t_count value is 2.246> 1.99897, it can be concluded that there is a contribution of multiple intelligences of students of the S1 Mechanical Engineering Study Program, Faculty of Engineering, Yogyakarta State University (X) to the learning outcomes of welding practice in the Undergraduate Program of Mechanical Engineering Education, Faculty of Engineering, Yogyakarta State University (Y).
Aerodynamic Performance Analysis of Open-Wheel Vehicle: Investigation of Wings Installation Under Different Speeds
Authors: Yudianto A , Susanto H A , Suyanto A , Adiyasa I W , Yudantoko A , Fauzi N A 
Published: December 2020

Abstract
An open-wheel vehicle with manual hybrid engine control with formula-like body shape was developed for a learning media at a vocational high school. This study aims to analyze the airflow of over the vehicle body as the effect of wing installation under various vehicle speeds. The investigations are to observe and evaluate the drag coefficient, drag force, lift coefficient, downforce, pressure distribution, streamlines, and velocity vector condition by emphasizing on the results from Computational Fluid Dynamics (CFD) simulation. The study found that installing the front and rear wings contribute to the decrement of drag coefficient 0.07 points and keeping the drag force relatively constant since the projection area changed. The benefit of having wings installed significantly increases the downforce by 334 N, which is 5.51 times higher than without wings in the speed of 150 km/h. However, the engine cover gives a significant obstacle to airflow, reducing the functionality of the rear wing. As such, the presence of the rear wing does not have a substantial effect on reducing the wake region.
Thermal Properties of Nano Tungsten - Ethylene Vinyl Acetate (EVA) Composites
Authors: Sobhy M. , Saleh Ahmed , Eid Alaa I , Khairaldien W. M. 
Published: January 2021

Abstract
Ethylene vinyl acetate (EVA) with different percentage of nano tungsten powder (0wt%, 30/wt %, 45/wt %, 60/wt%, and 70/wt %) composites (EVA/W nano-composites) were prepared by melt blending in a twin-screw brabender. The structural, morphological, thermal and mechanical properties of the prepared nano-composites were investigated using powder X-ray diffraction (PXRD), Scanning Electron Microscopy (SEM), thermogravimetric analysis (TGA), and dynamic mechanical thermal analysis (DMTA). It was found that the EVA composites show a higher thermal stability at high levels of tungsten loading.
Superior spectral performance of decoy flares compositions via inclusion of graphite as a black body emitter
Authors: Elbasuney Sherif , Elmotaz Amr A. , Sadek M. A. , Yehia M. , Tantawy Hesham 
Published: January 2021

Abstract
Graphite particles can offer high interfacial surface area as well as high emissivity as black body; therefore it can find wide applications in advanced decoy flares. In the current study, graphite particles of 100 µm size, were employed with different reactive metal fuels including Mg, Al, and Mg-Al alloy. Different formulations based on graphite ratio up to 8 wt % were developed via granulation with subsequent pressing. Thermal signature was measured using IR spectrometer (1-6 µm) Arc-Optics. Composite flare based on Mg-Al fuel, and graphite demonstrated superior spectral intensity; this formulation offered an increase in average intensity by 83 % to reference MTV flare. In the mean time, composite flare based on Al and graphite offered the highest relative intensity value θ of 0.6. Graphite, as an allotrope of carbon, can act as an excellent source of carbonaceous materials; that can strengthen incandescence emission. Furthermore Mg-Al reactive metal alloy can offer novel synergism as Mg could vaporize at 1000 °C offering efficient combustion process. It can be concluded that tailored flare with customized thermal signature can be developed.
Ionic Liquids based on Different Chain Fatty Acids as Green Corrosion Inhibitors for C-steel in Produced Oilfield Water
Authors: Atef Y , Ghanem A 
Published: January 2021

Abstract
The work presents the investigation of fatty acids based ionic liquid as green corrosion inhibitors for C-steel in produced oilfield water. Different-chain length fatty acids C6, C12 and C18-1 are mixed with di-ethanol amine (DEA) to synthesize some ionic liquids and evaluated the corrosion rates on C-steel surface using weight loss method and potential time measurements. The prepared ionic solutions were shown to be effective in reducing the corrosion rates as sustainable corrosion inhibitors. The polar unit is indicated as the reaction center for the adsorption process. Generally, the inhibition efficiency increases with increase the inhibitor concentration.
Thermal and potentiometric studies for complexes of Zr and Hf with some barbituric acid derivatives
Authors: Masoud M S , Hassan A S , Desouky N M , kamel H M , El-Kholany A S 
Published: January 2021

Abstract
The complexes of Barbital (Bal), Thiobarbituric acid thione (TBA), Thiobarbituric acid thiol (2-TBA), 2-Thiouracil (TU) with Zr (IV) and Hf (IV) were prepared. The structures and mode of bonding were characterized by elemental analysis, IR and electronic spectroscopy. Thermal analyses of the prepared complexes were done by DTA, TG, DSC techniques. The thermodynamic parameters were evaluated. The change of entropy values, AS#, for all the complexes lie within the range -0.267,-0.299 KjK-1 mol-1. The thermal processes proceed in complicated mechanisms with ordered transition states. In general, the complexes dissociated after losing small molecules such as H2O, Cl2 and CO. The decomposition is usually ended by the metal moiety. The DSC technique explained the effect of temperature on physical properties of some complexes. The glass transition phase doesn`t appear in all the complexes, while the crystallization temperature (Tc) was 780C-322.120C. Potentiometric titration studies calculated the dissociation constants of the ligands, the stability constants of the complexes and the distribution of species at different pH values.
Radiological and environmental studies on the metamorphosed sandstones at Wadi Sikait area, southeastern desert, Egypt
Authors: El-Farrash A. H. , El-Feky M. G. , Hassan S. F. , Abu Elatta Soliman A. , Refaat M. 
Published: January 2021

Abstract
Wadi Sikait area lies in the southern part of the Eastern Desert of Egypt along the upper stream of Wadi.Sikait. The exposed rock units in Wadi Sikait area are ophiolitic mélange roccks, metamorphosed sandstones, and porphyritic granites, lamprophyre dykes, in addition to fluorite and quartz veins. The activity concentrations of various radionuclides are measured by NaI-Tl activated detector and the radioactive mineralization were determined by Alpha track technique using CR-39 films. Radiometric investigations indicate that 238U activity concentrations range between 37.2 and 520.4 with average 148.8 BqKg−1, 232Th activity concentrations vary between 8.08 and 366.99 BqKg−1 with 76.75 BqKg−1 as an average. The studied metamorphosed sandstones have higher values relative the world concentration levels. High uranium content of the metamorphosed sandstone is attributed to presence radioactive minerals like uranophane and autonite, in addition to accessory minerals like allanite, zircon and monazite. Other U-bearing minerals are also recorded as biotite, muscovite, iron oxides and clays. Absorbed Dose Rate (D), annual effective dose equivalent (AEDE), radium equivalent activity (Raeq), external (Hex) and internal (Hin) hazard index, in addition to activity gamma index (Iγ) caused by gamma emitting natural radionuclide are determined from the obtained values of 226Ra, 232Th and 40K. Fairly, many of the studied metamorphosed sandstone do not satisfy the universal standards.
Sub-channel thermal-hydraulic analysis for VVER- 1000 generation III PWR
Authors: Almessallmy Alsherief M , Shaat Mohamed K , Hassanien Saeed A 
Published: January 2021

Abstract
The sub-channel thermal-hydraulic analysis of a nuclear reactor is essential for assessing of its safety aspects. In this paper, the VVER-1000 has been selected as an example of the third generation reactors since it meets most of the international safety standards and because it has been taken as a base for designing the VVER-1200 which is belonging to the III+ generation. A steady state mathematical model has been proposed and solved to validate and assure that the hottest channel temperature limits are satisfied. The various temperature distributions, the critical heat flux and the departure from nucleate boiling ratio (DNBR) for the hottest channel were evaluated. Also, a transient state model has also been presented and solved using the finite difference method with the aid of MATLAB algorithm. An exponential loss of flow rate of the reactor core coolant was triggered from the steady state conditions. We assumed that the neutron flux and the generated power were unchanged during the postulated event. The average core coolant flow time constant was treated as a single parameter expressing the rapidity of the event. A value of 250 seconds time constant was assumed for slow transient, whereas 10 seconds was assumed for fast one. The reactor core was assumed to be protected through the reactor control system and mitigated according to the regular emergency operating procedures. The time dependent temperature distributions were calculated for the cladding of the hottest coolant channel. For each value of the temperature, the response time required for reaching unsafe conditions was evaluated, discussed and presented.
Effect of the formation parameters on the thermal properties of La2Zr2O7
Authors: Abdelkareem Ahmed 
Published: January 2021

Abstract
Lanthanum zirconates has been suggested as a thermal barrier coating for many high temperature applications. This study is focusing on the effect of different preparation parameters on the thermal conductivity of La2Zr2O7. We have used solid state reaction to form the zirconates powder was very good homogeneity. We have studied the effect of the intimal ZrO2/La2O3 ratio, and found the 50% to be the optimum. The effect of the sintering temperature has also been studied and 1100°c was chosen as the optimum sintering temperature. The sintering time was also studied, where 3 hours was proved to be enough to obtain a homogeneous single phase compound with affordable method.
Preparation of magnetic nanoparticle biocomposites using rice husk and sugarcane bagasse fibers as the matrix
Authors: Dewi Y S , Wijayanti H , Lestari R A , Nata I F 
Published: January 2021

Abstract
Fiber is one of the important components to construct a matrix structure. Biomass is a potential material as a fiber resource for matrix. Rice husk and sugarcane bagasse consist of 36.6 % and 60% cellulose, respectively. This current research focused on evaluating the production of amine functionalized magnetic nanoparticle biocomposites produced by mixture of rice husk (RH) and sugarcane bagasse (SB) fibers. First, RH and SB fibers were dried and crushed close to 60 mesh for each, followed by a delignification at 80 °C for 2 h in 1% w/v of NaOH. Through by one-step solvothermal process, it was done by adding delignified ratio of RH and SB fibers (1:1; 1:2; 1:3; 1:4) to mixture of ethylene glycol, FeCl3.6H2O, and 1.6-hexanediamine at 200 °C for 6 h. The magnetic nanoparticles appeared on the fibers surface which contained 97.97% Fe. The magnetite was formed proved by the specific peaks at 36°, 43°, and 57° by X-Ray Diffraction.(XRD). The Fourier Transformed Infrared (FT-IR) identified N–H bending vibration and Fe-O in the biocomposites at 1640 cm−1 and 582 cm−1, respectively. The restructure of matrix, iron, and amine groups on the biocomposites surface can affect the adsorption capacity of various waste water treatments.