bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis of Ultrafine Fe-W-Al-Ti-Ni-C-B Powders by Mechanical Alloying
Authors: Chikhradze Mikheil , Abashidze Guram , Chikhradze Nikoloz , Tsverava David , Stecuła Kinga 
Published: November 2019

Abstract
The goal of the presented research was syntheses of the ultrafine and nanopowder blends by Mechanical Alloying from Fe-W-Al-Ti-Ni-B-C compositions for further application as a precursor for fabrication bulk High-Entropy Alloy (HEA) by explosive compaction technology. The presented paper describes the preliminary investigations of mechanical alloying of Fe-W-Al-Ti-Ni-B-C powders. Laboratory vibrating sieve equipment was used for sorting the initial powders for the reduction of particle size. For the experiments were used powders of Fe-W-Al-Ti-Ni-B-C system consisting of five major metallic and two minor non-metallic B and C elements were used for mechanical alloying. The crystalline coarse Aluminum, Titanium, Carbon and Nickel, fine-grained iron and tungsten and amorphous Boron powders were used as initial components. The Fe, W, Al, Ti and Ni powders were preliminary checked by “Explorer 5000 XRF” by Skyray instrument and verified. Based on the literature review, theoretical investigation and phase diagrams for mechanical alloying were selected two compositions with the following molar ratio: Fe20W15Al15Ti20Ni20B5C5; Fe25W25Al10Ti15Ni15B5C5; The mechanical alloying was realized on the high energy ball mill with zirconium oxide jars and balls. The ball to powder mass ratio was 10:1, the rotation speed was 500rpm. The process was carried out in dry conditions. The time of mechanical alloying was 5h, 10h and 14 h. The powders were prepared for preliminary analyses and assessment of particle size. The SEM and optical microscopy results of mechanical alloying are presented in the paper.
Analysis of the Consequences of Methane Combustion in a Mined Dog Heading
Authors: Tutak Magdalena , Brodny Jarosław 
Published: November 2019

Abstract
One of the most common and, at the same time, the most serious threats in underground hard coal mining, which often requires long rescue operations, is the methane hazard. It is related to the potential ignition and/or explosion of methane in mixture with air. The hazard grows along with the increasing depth of mining works and the concentration of production in mine headings. Methane, as an organic gas, is released to the mining atmosphere in the exposed body of coal. Accumulation of explosive concentrations of methane in a mine heading, as well as adequate oxygen concentration levels and the presence of a trigger (e.g. in the form of a spark) may lead to methane explosion or combustion. Methane ignition and combustion leads to a series of chemical reactions, which cause the emission of harmful and poisonous gases of high temperature into the mining atmosphere (the temperature of methane combustion in mixture with air is approx. 1,875°C, with methane content of approx. 10%). These gases are formed during methane combustion. Countering the methane hazard primarily involves elimination of the potential for dangerous methane concentration levels and application of suitable protective measures to prevent methane ignition. However, despite the preventive measures in use, there were 34 incidents related to the methane hazard in Polish hard coal mines in the years 2008–2018, including 10 cases of methane ignition in the mined dog headings. Therefore, it is necessary to carry out research in order to predict the consequences caused by methane combustion in mine headings. Taking into consideration the remarks above, it was assumed that the numerical analysis of methane combustion in the mined dog heading and of the impact of this combustion on the parameters of the air stream flowing through this heading would be conducted using the CFD method. The objective of the analysis was to determine the effects of methane combustion on the composition of the mining atmosphere and the physical parameters of the gas mixture generated in this process. The paper presents the distributions for the physical parameters of the resulting gas mixture and the concentration of fire gases. Moreover, it demonstrates the distributions for temperature and oxygen concentration levels in the heading under analysis.
Geostatistical Modeling by the Ordinary Kriging in the Estimation of Mineral Resources on the Kieselguhr Mine, Algeria
Authors: Lamamra Abdessattar , Neguritsa Dimitriy L , Mazari Messaoud 
Published: November 2019

Abstract
The most important step in a feasibility study of a mining project is the determination of reserves in situ. But the question which arises that no method of estimation can give exact value since there is inevitably an associated error when it is important to know the order of magnitude. Decision-makers need to know if the estimated content is correct or not. Geostatistics can help the mining engineer to obtain from the available information, and thus, enable him to decide if the project deserves more investments. Geostatistics provides not only the estimated value but also with the kriging variance, a measure of the accuracy of the estimate. This is one of the superiorities of geostatistics over traditional methods of estimating reserves. In this article, the Kieselguhr deposit reserve of the Sig mine (western Algeria) was evaluated according to the linear geostatistical method with ordinary Kriging (OK), to know the economic value of this mine that allows the exploitation of this deposit, and to carry out study cartography accompanied by 2D modeling of deposit. Finally, we obtained maps in which we could estimate exploitable and geological reserves, and know the characteristics of the deposit.
Refraction Correction of the Acoustic Wave in Multibeam Systems
Authors: Makar Artur 
Published: November 2019

Abstract
Dynamic surveys of the sea bottom that rely on determination of reflection points of the acoustic wave transmitted by the echosounder use the wave field theory for determination of the trajectories of the acoustic ray. Complex multibeam echosounder systems that use diagonal beams to determine the coordinates of reflecting points on the sea bed, must take into consideration the refraction phenomenon. Beam inflexion depends on the variability of sound’s velocity in water. It is increasingly more important for beams most inflected from the plumb line. It is a determinant of the angle zone of echosounder’s beam and swath width. The efficiency of bathymetric surveys relies on the swath width. It is 3-5 times the water depth for a multibeam echosounder and up to 12 times water depth for an interferometric one. High value of swath width achieved for high beams inflexion decreases the reliability of the Digital Sea Bottom Model built by data recorded during the bathymetric surveys. This article presents results of correction of the phenomenon of non-linear propagation of the acoustic wave in the multibeam echosounder calibration process in the area where the depth does not exceed 30m. A calibration test was utilised on the perpendicular profiles to determine the variance of depths. Depths measured by the diagonal beams were verified using a vertical beam during surveys on perpendicular profile. Popular models for determining the trajectory of an acoustic wave were used – one based on Snell’s law and another, a new one developed by TU Delft. The geospatial data was sourced using R2Sonic multibeam echosounder during the preliminary stage of bathymetric sounding.
Macroseismic Intensity Estimation from Instrumental Ground Motion Recordings in the Case of Small and Moderate Vrancea Subcrustal Earthquakes
Authors: Adelina Moldovan Iren , Petruta Constantin Angela , Luminita Ardeleanu , Constantin Ionescu , Bogdan Grecu , Marius Manea Liviu , Dragos Toma Danila , Victorin-Emilian Toader , Raluca Partheniu , Florinela Manea Elena , Alexandru Tiganescu , Otilia Placinta Anica 
Published: November 2019

Abstract
Romania is one of the most seismic-prone countries in Europe due to the periodically occurrence of strong intermediate-depth earthquakes in Vrancea seismogenic zone. The Vrancea area is located beneath the South-Eastern Carpathian Arc bend, at the contact between the East - European plate and the Intra-Alpine and Moesian sub-plates. An intense seismic activity is recorded in the mantle, within a narrow, almost vertical descending volume between 60 and 180 km depth. Earthquakes with magnitudes larger than 5.0 (Mw) and macroseismic effects exceeding V MSK degrees on extended populated area occur in Vrancea seismic zone, with a return period of around 2 years. Besides the extended scientific studies, the near real time estimation of the macroseismic intensity recently became mandatory for the insurance companies to cover some of the losses and damages that earthquakes might cause to houses, belongings, and other buildings. The first approach to obtain intensity values was to develop an online environment for collecting people feedback regarding the effects of earthquakes and for the automatic approximation of the intensity. The automatic intensity estimation code from the online feedback proposed by [1], [2] and adopted by [3] for the Romanian earthquakes was improved and used for this study. Additionally, there were used prediction equations to obtain intensity values from the epicentral intensity, and epicentral and hypocentral distances. Besides the estimation of macroseismic intensities from online people feedback and from attenuation relations, equations for conversion of peak ground acceleration in macroseismic intensity were also required for a rapid evaluation of ground motion effects. In order to avoid the increase of the prediction uncertainties, the data must be selected in such a way that they represent the parameters’ rank for which the prediction will be accomplished and the selected data must be representative for the investigated regions and seismic source. In this paper were developed conversion methods from PGA to macroseismic intensity for moderate intermediate depths earthquakes with 4.5<Mw<6.0. All the studies were realised in the case of Vrancea recent (2014-2019) moderate intermediate depth earthquakes, felt on the extra-Carpathian region.
Mapping of Induced Effects of an Earthquake in the Region of Algiers, Algeria Using the Geographical Information System GIS
Authors: Sadou O. , Bourenane H. , Louni C. , Balla N. , Haddouche A. 
Published: November 2019

Abstract
Landslides, rock blocks falls, liquefaction, the appearance of the surface fault and flood present the principle geological-hazard in relationship with earthquakes which will be mapped in the region of Algiers. The determination of these areas passes through a qualitative and quantitative analysis based on a recognition of the soil conditions; geological, lithological, hydro-geological, topographic, morphological and geotechnical. The assessment and mapping of the degree of induced hazard allows individualizing homogeneous areas that can behave similarly during the earthquakes.
Risk charter for medieval defensive earthen architecture in southern Spain
Authors: Manrique Jesus Garrido , Gutierrez-Carrillo Maria Lourdes , Melgarejo Emilio Molero 
Published: November 2019

Abstract
Medieval defensive earthen architecture is typically represented by big and well maintained defensive walls, lookout towers or castles despite mostly represented by remains of tower walls or defensive walls. While studies on natural hazards have been carried out concerning these castles or lookout towers, there are no studies on defensive walls. Both are certainly significant from a cultural heritage perspective, despite the fact that the latter are less popular for the general public. In Southeast Spain, most of this kind of architecture has been affected, and occasionally reconstructed, by destructive earthquakes and/or landslides, in accordance with historical chronicles or field evidence, however, there are no records of low-scale natural hazards. Hence, aware of the importance of the prevention of natural hazards regarding the conservation of the cultural heritage, a National Emergency and Risk Management Plan for the Cultural Heritage, a National Plan for Preventive Conservation as well as a National Plan for Defensive Architecture have been enacted by the Spanish Ministry of Education, Culture and Sport. According to these plans, a risk charter, including natural and man-made hazards, should be completed in order to improve investment programming. Cultural heritage risk and cultural assets maps should be connected in order to become an instrument for managing preventive conservation. Natural hazards studies should be conducted in order to protect cultural heritage, though they are not usually performed, most likely due to their cost. However, some natural hazards studies have been published in scientific journals, mainly signed by university researchers or various Spanish research institutions such as the Geological and Mining Institute of Spain. Some of them, including the Spanish Seismic Network or the old Ministry of Environment (currently known as the Ministry for Ecological Transition), have published several hazard and risk maps which can be usually used in GIS format. Yet, most of them are not even known by researchers on cultural heritage due to the different administrative levels in charge of natural hazards. In this paper, some recommendations to prevent natural hazards in medieval defensive earthen architecture will be discussed.
Proximate and Ultimate Analysis Before and After Physical & Chemical Demineralization
Authors: Bilen Mehmet 
Published: November 2019

Abstract
In this study, a total of 12 coal samples were collected. Physical and chemical cleaning were employed on these collected coal samples. In order to understand the effect of physical & chemical cleaning on these samples, samples characterization were performed in terms of proximate and ultimate analysis. Calorific values of each corresponding clean coal samples were also determined. After chemical cleaning calorific values of each sample decreased, while chemical cleaning resulted in ultra clean coals as regards to ash content (average of 0.5 % ash content). Volatile matter content each corresponding sample after chemical cleaning have higher percentage with respect to the ones after physical cleaning. However for some specific sample, the increase in volatile matter content after chemical cleaning is more than 200 %. Fixed carbon percentages do not show tremendous changes as regards to chemical cleaning, however they decrease for some and increase for some other after chemical cleaning. Calorific values decreases for the all samples after chemical cleaning. Ultimate analysis (C, H, N and O) was also determined after physical and chemical cleaning. Sulphur decreased for all samples after chemical cleaning as expected. Taking these variations into consideration, calorific value decrease were deducted and possible reasons of this decrease was inferred. Corresponding differentiations were compared to calorific value differentiation and the most significant reasoning of the calorific value decrease was evaluated.
Logarithmic expression of Globigerina bulloides shell evolution through the biometric analysis: Paleoceanographic implications for the late Quaternary
Authors: Zarkogiannis Stergios , Kontakiotis George , Antonarakou Assimina 
Published: November 2019

Abstract
Fossil foraminifera are a treasure trove of information in applications ranging from microevolution to paleoclimatology. The architecture of their tests is of the key importance in systematic and phylogenetic studies and can reveal micro-evolutionary traits through the biometric analyses. In the present paper, we analyze the laws of growth that control planktonic foraminifera shell morphology. We report the results of a biometric study of the temporal variation in the shell shape and chamber size of the cosmopolitan, subpolar to temperate species Globigerina bulloides d’Orbigny from core top sediments in the eastern tropical Atlantic Ocean. Morphological variation in terms of test shape and adult chamber size in G. bulloides, has been measured in 116 down core sediment samples from the tropical waters (19°N) of the northern Antarctic Ocean and has resulted in a model that simulates the basic morphology (chamber size and spatial arrangement) of planktonic foraminiferal shells of that species. The investigated samples comprise a continuous record that spans the last 200 kyrs. The specimens for this morphometric study were picked from a restricted sieve fraction and were mounted for Scanning Electron Microscopy (SEM) analysis. The restricted size of the specimens constrained the analysis to adult specimens and minimized ontogenic effects while allowing the documentation of very small overall changes in the parameters under investigation in time. The dimensions that were measured for each test were its height, width and the diameters of the last seven chambers. This allowed the determination of chamber centers and their analogies resulting in a mathematical model based on a logarithmic spiral equation that describes the evolution of the test with the growth during their adult phases. The model presented herein belongs to a family of so-called “fixed-axis” coiling models.
Modelling of Work of Cut and Stretchy Sheet in Span Beam Structures with the Mixed Reinforcement
Authors: Burchenya Sofiya , Famulyak Yuriy , Sobczak-Piastka Justyna 
Published: November 2019

Abstract
The constant growth of the intensity and volumes of automobile transportation causes the necessity of the increasing the requirements to the serviceability of transport facilities. The issue of the serviceability and safe operation of the existing highway or pedestrian bridges, which were built many years ago, is always relevant. Therefore, there is a choice: either to restore and strengthen the existing facilities or to replace them completely. It is expedient and efficient to use a steel cut and stretchy sheet in the form of the external ribbon reinforcement at the strengthening of the reinforced concrete span bridge structures. In the future, the steel cut and stretchy sheet is properly attached to the surface of the structure and the filling of the sheet cell is done by the layer of the cement and sandy solution (the process of concrete spraying) or protected by a concrete layer for the prevention of the sheet corrosion. Such a cut and stretchy sheet can be effectively used in new structural elements at new construction as a working longitudinal or transversal reinforcement. An effective version of the use of the cut and stretchy sheet is possible for the strengthening not only bending structures but also compressed and compressed out of center reinforced concrete and stone ones. Thus, the issue of the research and modeling of the work of the steel cut and stretchy sheet in the array of concrete under the linear stressed state conditions is of vital importance. The article presents the results of the experimental and theoretical research of the work of the steel cut and stretchy sheet under load; provided the physical model of such a process; substantiates the effectiveness of its use and the placement in span beam bridge structures.
Influence of Freeze-Thaw Temperature on Load-Bearing Capacity of Steel-Concrete Beams Carrying Transverse Loads
Authors: Famulyak Yuriy , Hrytsevych Andriy , Sobczak-Piastka Justyna 
Published: November 2019

Abstract
The use of steel-concrete structures in which, external or extra-strong non-stressed sheet reinforcement are widely used in the stretched (sometimes in the compressed zone) in industrial construction as well as in the process of bridges and tunnels construction. Such structures are continuously thermal loaded during operation. Existing calculation methods of steel-concrete structures do not allow accurate estimation of the influence of freeze-thaw temperatures because there are contradictions considering this problem. The method of frost resistance calculating in Ukraine researches concrete cubes but it does not take into account the existence of reinforcement in the construction, its quantity and placement in the cross-section. This problem became even more relevant under conditions of Ukraine transition to the European design standards. According to the demand of the Eurocode the number of cross reinforcement in the back-up area is increased in comparison with national design standards. Single-span steel-concrete beams were manufactured and examined in order to determine the influence of freeze-thaw temperature on the constructions. Flat deformed reinforcement was adopted for the perception of tensile forces. To determine the strength characteristics of concrete, cubes and prisms were additionally made from the same concrete as the beams. To determine the freezing point of the beam and measure its internal temperature, 10 thermocouples were introduced into the beam’s body. On the basis of the adopted research method a graph of the freezing rate of the experimental beams and the destructive influence of freeze-thaw temperature on the load-bearing capacity of the steel-concrete beams were obtained.
Hydraulic Computer Analysis of a River Sector Under Altered Flowing Regime Due to an Existing Bridge and Suggested Specific Correction Works
Authors: Popescu-Busan Ioana - Alina , Lazar Gheorghe I. , Constantin Albert Titus , Nicoara Serban-Vlad 
Published: November 2019

Abstract
The paper presents a 2D numerical modelling of the water flow transit under an altered regime on Strei River, specifically for a 633m stretch influenced by a driveway crossing concrete structure of four gaps (about 71m total span) on a national road outside of Deva Town, Romania. The analysis considers a possible (and requested by specialised regulations) accidental highwaters flow development as assimilated from a specific hydrologic phenomenon that occurred on site during the special spring season of 2000. Taking into consideration the findings and general flow improvement suggestions of a technical expertise ordered by the rivers national administration, the present developed hydraulic model follows the technical recommendations of a formerly feasibility study with respect to streambed correction in the range of the mentioned bridge, specifically the downstream accomplishment of a bottom step (for scourings re-siltation) and two left side river groins (to direct the stream flow towards the central span of a following railway bridge, not covered by present model), accompanied by banks protection and alluvia deposits removing works. Under the given flow and geometry conditions, the study accomplished by the help of HEC-RAS 5.0.6 specialized software package looks to estimate the water surface level and velocity development in space and time, and so to draw the future state of flow transition along the analysed sector. As about the simulation output, the most important conclusions are that the riverbed would be able to discharge the significant flow of 0.1% overrunning probability at a maximum surface level below the structure safety values. In the same time, the reached velocity and particle tracking visualizations suggest a more stable and efficient riverbed time behaviour.