bluuebunny/crossref_metadata_2025_split huggingface dataset:
Propagation of the trajectories for reentry spherical debris including rotation, melting fragmentation and voxel method
Authors: Murcia P J O , Guedes U T V , Prado A F B D 
Published: November 2019

Abstract
It is estimated that more than 22.000 objects are in orbit around the Earth, with a total mass of 8.400.000 kg. These numbers consider only objects with dimensions above 10 cm and some non-operational, but still orbiting satellites without control (debris). The debris represent a hazard to operational satellites and aerospace operations due to the high probability of collisions. Due to the interaction of the debris with the atmosphere of the Earth and the solar activity, they began to lose energy and finally decay. During the de-orbit process, the debris fall into the Earth’s atmosphere at hypersonic speeds and these objects can break-up and/or be fragmented due to the aerodynamics, thermal and structural loads. It is important to obtain the trajectory and attitude of any fragment to determine the possible survival mass, impact area, hazard conditions and risks to the population, the air traffic control, and infrastructure. In this case, it is implemented a computational code to integrate the equations of motion to propagate the dynamics and kinematics of spherical debris or propellant tanks. It is also analyzed the results of trajectories with six degrees of freedom, atmospheric winds, and Magnus effect. A voxel method is implemented to analyze the tanks heat transfer, surface temperature and structures stress. To determine and observe the influence of the rotation and the Magnus force in six reentry spherical bodies, three materials are selected; aluminum alloy, due to its application in many aerospace structures; titanium and graphite epoxy I, due to their highest melting point and specific heat. Generally, these materials are used in tanks and rocket motors. More than 62 trajectories were simulated. The mathematical model and computational code were validated in three degrees of freedom. Results are compared with data from other computational tools available in the scientific literature. The results show a good approximation with reported cases of study. New results are generated in the simulations of rotational bodies, due to the influence of aerodynamic forces in the trajectory and the changes in the stagnation regions. Due to the implementation of wind and rotation of the debris, the fragments increased the survivability and the dispersion area.
The use of Design of experiments to calculate the influence of planet oblateness in the temporary gravitational capture
Authors: Siqueli Guilherme A. , Antônio F. B. A. Prado , Solórzano Carlos R. H. 
Published: November 2019

Abstract
This paper presents the study of the influence of the oblateness of one planet in the temporary gravitational capture of a particle (or a spacecraft) around the main celestial body of the system. The gravitational capture is a physical phenomenon where a celestial body (or a spacecraft), initially in a hyperbolic orbit with positive energy with respect to the main body of the system, is captured by another celestial body, changing the energy of the orbit to negative during a determined time. In this way, we have a temporary capture of this body or spacecraft. In the case of a spacecraft, it is possible to make this capture permanent by the application of a propulsion system to the spacecraft. This technique is done with savings over the traditional maneuvers performed without the support of the temporary capture, so it can help mission designers in the planning of the mission. As an example, the system used in the present paper is composed by the Sun-Jupiter-particle, and this system is modeled by the circular restricted three-body problem (CR3BP) plus the oblateness of Jupiter. To determine the effects of the oblateness in the dynamics of the particle, it is used the design of experiments to generate the data for a global analysis of the model. The oblateness of the planet is varied to show the effects of this parameter.
Simulations without data updates using analytical attitude propagator GSAM for spin stabilized satellites
Authors: Zanardi M C , Mota V , Borderes-Motta G 
Published: November 2019

Abstract
The objective of this work is to validate the GSAM propagator using new data provided by the National Institute for Space Research (INPE) from SCD1 and SCD2 data collection satellites, with emphasis on long interval simulations without daily data updates. Originally, only 40 days of data were available to test the program, constraining any attempts to measure its precision more accurately. Recently, over two decades of data regarding both satellites’ orbital and attitude parameters were provided, allowing further studies and validation of the program. The rotational motion equations are composed by the gravity gradient torque, aerodynamic torque, solar radiation pressure torque, residual and eddy current magnetic torques, the latter using a dipole geomagnetic model. The results are considered fitting when the mean deviation between the calculated variables and the real satellite data stay within 0.5° for the right ascension and declination angles and 0.5 rpm for the spin velocity. Intervals that meet the required precision were found for all years, from three to up to 15 days of simulation without data update. The consistent detection of such intervals further corroborate the use of the propagator to estimate the orientation of the satellites studied in their missions.
Database on detected stellar occultations by small outer Solar System objects
Authors: Braga-Ribas F , Crispim A , Vieira-Martins R , Sicardy B , Ortiz J L , Assafin M , Camargo J I B , Desmars J , Lecacheux J , Santos-Sanz P , Duffard R , Benedetti-Rossi G , Gomes-Júnior A R , Morgado B , Rommel F L , Margoti G , Pereira C L 
Published: November 2019

Abstract
Observation of stellar occultation by objects of the Solar System is a powerful technique that allows measurements of size and shape of the small bodies with accuracies in the order of the kilometre. In addition, the occultation star probes the surroundings of the object, allowing the study of putative rings/debris or atmosphere around it. Since 2009, more than 60 events by trans-Neptunian and Centaur objects have been detected, involving more than 34 different bodies. Some remarkable results were achieved, such as the discovery of rings around Chariklo and Haumea, or the high albedo of Eris, the lack of global atmosphere around Makemake and the discovery of the double shape of 2014 MU69, among others. After the release of Gaia catalogues, predictions became more accurate, leading to an increasing number of successful observations of occultation events. To keep track of the results achieved with this technique, we created a database to gather all the detected events worldwide. The database is presented as an electronic table (http://occultations.ct.utfpr.edu.br/), where the main information obtained from any occultation by small outer solar system objects are listed. The structure and term definitions used in the database are presented here, as well as some simple statistics that can be done with the available results.
Hall plasma thruster development for micro and nano satellites
Authors: Ferreira J L , Martins A A , Miranda R A , Porto M C F , Coelho H O 
Published: November 2019

Abstract
Hall thrusters are one of the most successful electric thrusters for space application that has been developed until now. The Plasma Physics Laboratory of the University of Brasília (UnB) has been developing a Permanent Magnet Hall Thruster (PHALL) for the Brazilian Space Program since 2004. Recently we have achieved important experimental results satisfying our initial goals of generating a force above 40 mN with powers around 620 W. We will discuss in this article possible applications of this thruster to nano and microsatellites with powers above 50 W. Meanwhile, a complete description is given of our present and future installations where the new thruster will be tested; taking advantage of our new 1.5 m diameter vacuum chamber (the old chamber had 0.5 m in diameter), which intends to test our thruster in the most realistic conditions, including mounting and testing on a 3U CubeSat structure, which is where we intend to start testing our thruster in a real mission in space.
Evaluation of orbital decay of a satellite at low altitude due to atmospheric drag as a function of solar activity
Authors: Macêdo C F C , Rocco E M 
Published: November 2019

Abstract
Artificial satellites in low Earth orbit have as main disturbance the atmospheric drag, which is a non-conservative disturbance that causes the satellite to lose orbital energy due to the friction with the air. Basically, the drag force is a function of the velocity, the local air density and the satellite’s constructive parameters. The air density is a function of altitude, longitude, latitude, geomagnetic index and solar activity. Solar storms are responsible for a wide range of terrestrial effects, especially in damage to telecommunications systems. Another relevant effect of solar activity is the variation in the volume of the atmosphere and consequently in the value of the air density for a given altitude, longitude and latitude. This work provides an initial approach, through simulation, in the engineering effort to deal with this disturbance.
The role of the mean and forced eccentricities in the secular dynamic of circumbinary planets
Authors: Zoppetti F.A. , Beaugé C. , Leiva A.M. 
Published: November 2019

Abstract
Within the framework of the Restricted Three Body Problem (RTBP), we consider the orbital evolution of a circumbinary (CB) planet. We develop a simple analytical model to explain the mean behaviour of the planetary eccentricity and better identify the nature of the main contributors of eccentricity oscilations. Our theory is validated by comparing with N-body simulation. We analyse the effect of including dissipative forces in our theory and compare with a N-body simulation in which the dissipative force is the interaction with a protoplanetary disc. Finally, we use our model to explain dynamical maps in the CB region and distinguish domains where the secular dynamics dominate over the resonant perturbations.
New adsorbent materials on the base of minerals and industrial waste
Authors: Kotova Olga 
Published: November 2019

Abstract
At present, when environmental problems become more pronounced, we need to find special solutions. One of the ways is to use cheap adsorbents that do not need to be restored. An example of developing a class of adsorbent materials is technology for synthesizing nanotubes from refractory ilmenite-leucoxene ore. Another example of the development of a class of zeolite as advanced materials is the technology of their synthesis from ashes of thermal power plants. Synthesis conditions create necessary parameters of adsorption properties to remove heavy metals and radionuclides. “Clean” technologies are formed to replace natural and commercial zeolite. Production of such materials at the national level can be an important source of profit, can create new jobs and increase competitiveness of the industry.
The Influence of Cr doping on the Structural and Magnetic Properties of HoMnO3 Multiferroic Ceramics
Authors: Ibrahim J. F. M. , Mergen A. , Parlak Umut , Kurovics Emese 
Published: November 2019

Abstract
In this research single-phase Cr-doped HoMnO3 ceramics were synthesized via solid state reaction method. The structural and magnetic characteristics of the prepared samples were examined using various characterization techniques, including x-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDX) and vibrating sample magnetometer (VSM). All samples exhibit single phase that emphasized by SEM and XRD. Magnetic properties of the prepared samples at low temperature (10K) showed the presence of different magnetic characteristics. The change in magnetic behavior could probably occur due to slight decrease in the unit cell volume that leads to a structural distortion in the lattice. Cr-doped HoMnO3 could be a good candidate with a better ferromagnetic property for practical multiferroic applications.
Computer simulation of damage to metal-ceramic composites under shock loading
Authors: Karakulov V V , Smolin I Yu , Kulkov S N 
Published: November 2019

Abstract
In this work the results of studying of the mechanical behaviour of metal-ceramic composites with an aluminium matrix on mesoscale level are submitted. Computer simulation of mechanical reaction of representative volume of composite material, considered as ensemble of the interacting structural elements (ceramic particles and metal matrix), is used for studying processes of the nucleation and growth of damages on mesoscale level of metal-ceramic composites under the loading by shock pulses. The sizes of representative volume give the possibilities to enter effective mechanical parameters of a composite material. The mechanical behaviour of aluminium matrix is described by the model of the damaged elastic-plastic medium. The model of the damaged brittle solid is used for ceramics. The problem is solved in 2D statement with application of finite-difference method. The results of computer simulation show that the local tensile stresses can appear in unloading wave and can cause damages in ceramic particles. In the region of composite where two opposing unloading waves interacts (spall zone) the calculation predicts the existence of cracked ceramic particles, local damages in metal matrix and existence of mesoscale and macro-scale cracks.
Electrochemical study of the corrosion inhibition effect of 3-cyanophenyl compound on 420 martensitic stainless steel in strong acid media
Authors: Loto Roland T. , Ayozie Bryan U. , Loto Cleophas A. 
Published: November 2019

AbstractThe corrosion inhibition performance of 3-cyanophenyl organic compound on heat treated 420 martensitic stainless steel in 6 M H2SO4was evaluated through potentiodynamic polarization test, ATR-FTIR spectroscopy and adsorption isotherm studies. Results obtained proves the compound to be effective with highest inhibition performance value of 99.4%. The inhibition property was determined to be mixed type inhibition with significant anodic inhibition tendencies. Adsorption of the compound onto the steel was through chemisorption mechanism in agreement with the Langmuir and Freundlich isotherms models at correlation coefficients of 1 and 0.7570. The transmittance of detected functional groups of 3-cyanophenyl diminished at distensible wavelengths because of excellent surface coverage and adsorption of the compound onto the steel
Comparative investigations of the selective Co etching from hardmetal support layer of diamond coating
Authors: Rugóczky Peter , Muránszky Gábor , Lakatos János 
Published: November 2019

Abstract
Selective cobalt etching from WC–Co composite usually carry out prior diamond deposition was investigated. Diluted Caro’s acid as primarily utilized etching reagent was used. The cobalt and tungsten dissolution from hardmetals (HM) were determined as a function of time and a comparison were done in case of different grade hardmetals. For comparison beside the hardmetals the pure metallic cobalt and binderless, plasma sprayed tungsten carbide dissolution also has been tested. Hot filament chemical vapor deposition (HFCVD) technic was used to investigate the diamond nucleation on the differently pre-treated samples. The investigation highlighted for that: a) the selective cobalt etching can due to the different rate of dissolution of the two components, however the dissolution of the WC was not zero, b) the dissolution rate governed by the composite substance structure by the pore size which has formed during the selective dissolution process, therefore the dissolution rate of both components was found to be influenced by the grain size of WC and the cobalt content of the hardmetal. c) The removed cobalt quantity from the hardmetal surface has strong effect on the diamond nucleation during HFCVD method. Based on this research a better understanding of the mechanism of the pre-treatment and a chance for optimizing the selective cobalt etching from hardmetals prior diamond deposition will be achieved.
Formation of metastable zirconium oxides using pulsed laser deposition of ZrO based target
Authors: Křenek Tomáš , Mikysek Petr , Pola Michal , Vála Lukáš , Melaré Estela , Jandová Věra , Vavruňková Veronika , Rieger David 
Published: November 2019

Abstract
There is a growing interest about the possibilities for preparation of various zirconium oxides from scientific as well as application point of view. Laser ablation of solid target consisting of sintered grains of metallic hexagonal Zr3O and monoclinic ZrO2 results in evaporation of Zr, O species (ions, atoms) and subsequent deposition of Zr-O film. Ta and Cu have been used as substrates. The films were analyzed by SEM-EDX, Raman and FTIR spectroscopy and X-ray diffraction. SEM analysis revealed µm/sub-µm sized roundshape and ring-like objects on continuous coat. Using Raman spectroscopy broad peaks which can suggest partial laser induced amorphization of Zr-O deposits were detected. FTIR spectroscopy shows bands which are assignable to Zr-O vibration of nanostructured zirconia. X-ray diffraction analysis provides more explicit assignment of deposited phases where the deposit on Ta exhibits presence of monoclinic ZrO2, oxygen deficient rhombohedric Zr3O and interestingly indicates presence of high-pressure orthorhombic ZrO2 phase. The coat on Cu consists of monoclinic ZrO2, rhombohedric Zr3O, and metastable tetragonal ZrO2 phase.
Synthesis and Characterization of Carbon Nanosheets from Stinging Nettle (Urtica Dioica)
Authors: Nuilek K , Simon A , Baumli P 
Published: November 2019

Abstract
Extensive research in nanotechnology has allowed us to improve and revolutionize technology and industry. This had led to an interest in the synthesis of other forms of carbon nanomaterial, such as graphene, fibre, carbon nanotubes and particles. Nowadays, a variety of carbon materials is available offering the flexibility to modify carbon properties. Therefore, the manufacture of carbon materials in different shapes is a likely way to take advantage of the morphology and relate it to the properties of the carbon nanomaterial. Stinging nettle is a new material to study for the production of carbon nanostructured materials. In this research, carbon nanosheets were successfully prepared from stinging nettle (nettle stem and leaf) using potassium hydroxide (KOH), sulphuric acid (H2SO4) and thermal treatment. This method is simple for producing carbon nanosheets from natural materials. Treating the nettle stem with KOH (solid) produces carbon nanosheets with a thickness of ∼159.2– 252.3 nm, while KOH (solute) treatment led to thinner nanosheets (∼70.43–111.2 nm). SEM micrographs of the nettle leaf with KOH (solute) activation show a smooth surface and clearly reveal the formation of carbon nanosheets. However, in the samples activated by KOH (solute) a greater number of micropores were found on the wall. The microstructure and morphology of the samples were investigated by scanning electron microscopy (SEM), the chemical composition was analysed by energy-dispersive X-ray spectrometry (EDS).
Band Structure of Phononic Crystal Consist of Hollow Aluminum Cylinders in Different Media; Finite Element Analysis
Authors: Ozer Zafer , Demir Mehtap , Mamedov Amirullah M. , Ozbay Ekmel 
Published: November 2019

Abstract
In this study, we investigated band structure of a 2D Phononic Crystal (PnC) which was consist of hollow aluminum cylinders in different media. To validate the finite element predictions, we made a square lattice PnC which has lattice constant a = 14mm, outer radius r1
= 5mm and inner radius r2
= 4mm of cylinders. In our experimental measurement, by using a signal generator software, we sent 100 Hz-20kHz sine signal for 5 seconds duration from speaker to the PnC where placed 1m away from. With the help of a microphone, we recorded the sound in front of the PnC (Pin
) and backside the PnC (Pout
). Then we were converted our recording into frequency domain by standard FFT algorithm, we calculated the Transmission Loss value according to the formula TL = 20*
log10
(Pout
/ Pin
) and obtained the experimental Transmission Loss. After experimental validation, we conducted band structure analysis of different combination of the 2D PnC by finite element method.
Application of finite element method (FEM) to study stress-strain state and distribution of temperatures in cutting zone in turning of various structural materials by carbide tools with coatings of various composition and architecture
Authors: Vereschaka Alexey , Mokritskii Boris , Mokritskaya Elena , Sharipov Oleg , Sotova Catherine 
Published: November 2019

Abstract
The paper considers simulation of cutting process conditions and state of a metal-cutting tool using the finite element method (FEM). The study considered the distribution of normal equivalent and tangential stresses in workpiece material during turning of aluminum-deformable alloy G-AlMg5 (DIN 1725) and copper C11000. Based on the calculated stress values, the values of plastic strains of the workpiece material were determined throughout the whole process of turning with the necessary time sampling of the process. The distribution of temperatures in cutting zone during turning of steel 5135 by carbide tools with coatings of different composition and thickness was studied. The obtained results were compared with the data obtained during the corresponding cutting tests. The paper considered the influence of such coating parameters as thickness, element composition and architecture on distribution of temperatures in a workpiece, cutting tool and chips during the cutting process.
Extra pure tellurium oxide for the growth of high quality paratellurite crystals
Authors: Grishechkin Mikhail , Islam Anika , Khomyakov Andrew , Zykova Marina , Mozhevitina Elena , Avetisov Roman , Ermochenkov Ivan , Avetissov Igor 
Published: November 2019

Abstract
Tellurium oxide (IV) single crystals are in demand materials for manufacturing acousto-optical devices optical fibers for IR wavelength range. The initial material for production of active and passive optical materials must have purity better than 99.999 wt% and extremely low concentration of the residual water. The main method of synthesis of TeO2 is oxidation in nitric acid followed by recrystallization from HCl is complicated, also amount of used high purity acids and waste are very high. Besides the residual water content is no less than 10 ppm. In the research we have developed the procedure for the synthesis of high-purity tellurium (IV) oxide without the usage of liquid oxidants. The process of oxidation of elementary Te was carried out in a flowing quartz glass reactor. Air oxygen was used as an oxidizing agent. The oxidation was conducted at 600-670°C during 24 hours. The produced material was a fine crystalline powder of acicular dendritic crystals of bright white color, identified as β-TeO2 due to X-ray. It was as pure as 5N7 due to ICP-MS. The β-TeO2 crystal grown form the synthesized water-free preparation has demonstrated better optical properties towards the crystals grown from commercial TeO2, produced by the «wet» technology.
Structure and mechanical properties of ZrO2-MgO composites with bimodal pore structure
Authors: Buyakov A , Buyakova S , Kulkov S 
Published: November 2019

Abstract
Porous ceramic ZrO2-MgO composite in a wide range of component content was studied. The effect of content and sintering parameters on pores size, its distribution, lattice structure, coherently diffracting domains and lattice microdistortion, tensile strength was investigated. It has been shown that the adding of pore-forming particles into the initial powder makes it possible to obtain a bimodal pore structure of composites. Sintering time and MgO content in ceramics are stipulated a changing of the average size of macro- and micropores and microstresses, which determine the macroscopic strength of the material.