bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dynamics control of powered hydraulic roof supports in the underground longwall mining complex
Authors: Rudzki P , Krot P 
Published: December 2021

Abstract
The study presents the dynamic analysis of the hydraulic cylinders operated in the powered roof support sections as an important part of the longwall underground mining complexes. This type of hydraulic unit is subjected to frequent shock impacts from the significant rock masses released on the top of mined caverns. Hydraulic props are equipped with safety valves with steel helical springs, which intend to reduce peak loads by the relief of internal pressure. These valves respond to shock with a time delay due to the limited velocity of the pressure wave inside the cylinder and an additional pipe of a small section, which restricts fluid flow in outer space. The new approach represented in this paper is based on mathematical modelling of the interaction of the hydraulic and mechanical parts and using additional signals to control safety valves. Detection of shock in advance (0.02-0.05 s) allows reducing pressure peaks by 30% and avoid failures. The challenges are the development of a “smart valve” with optimised control functions by the signals from additional sensors (vibration, deformation, piston position) and providing fast reaction time with a high flow rate under pressures up to 100 MPa.
Parametric simulator of cyclic and non-cyclic impulsive vibration signals for diagnostic research applications
Authors: Michalak Anna , Wodecki Jacek 
Published: December 2021

Abstract
In recent years cyclostationary analysis of vibration signals is considered to be one of the most potent approaches for diagnostics of machines with rotating components. However, it is a subject of an extensive research towards extending its robustness due to its significant inefficiency in the presence of non-cyclic impulsive components in measured data. This problem is especially visible in datasets measured on machines such as ore crushers, where the high-energy impacts are a natural phenomenon. Unfortunately, due to practical inaccessibility, real-life datasets necessary to properly study this problem are extremely difficult to obtain. To address this issue, the authors propose an easy to use simulator of impulsive components. It covers both cyclic components that can describe various types of fault signatures, and non-cyclic ones that can represent impacts occurring naturally due to the nature of machine operation. Simulated signals have been compared with real ones to ensure a high similarity degree, which in turn guarantees a relatively high level of realism.
Analysis of the vibro-acoustic data from test rig -comparison of acoustic and vibrational methods
Authors: Zimroz Paweł , Shiri Hamid , Wodecki Jacek 
Published: December 2021

Abstract
Detection of damage is a significant issue in providing efficiency and safety in industrial processes. In underground mining much research effort is made for developing an automatic system of diagnosing the machinery using robots. One of the major groups of equipment utilized and maintained in the mines is rotating machinery. Local damage occurring in such machines commonly have a cyclostationary character in short term as any change in their characteristics is expected to repeat periodically. In most cases they can be easily detected based on vibration signals measured with contact sensors (accelerometers). However if mobile robots such as UAV (unmanned aerial vehicles) are planned to be used, remote measurement is firmly preferred. In this paper we compare vibrational detection with a novel approach based on analysing an acoustic signal recorded by a microphone.
Preliminary sources identification of nitric oxide (NO) emissions in underground mine
Authors: Banasiewicz Aleksandra , Wroblewski Adam , Gola Sebastian 
Published: December 2021

Abstract
Gas hazards in Polish underground mines are a major problem for the ventilation service. Ensuring appropriate environmental conditions is becoming increasingly difficult, especially with the introduction of new, more stringent restrictions on the concentration limits of harmful gases. According to [1], the most dangerous gases in underground mines are carbon monoxide, hydrogen sulfide, nitrogen oxides, c arbon dioxide, sulfur dioxide, and m e thane. T ogether with the introduction of new limit values for the above-mentioned gases by the European Union, it is necessary to accurately identify the sources of their emission in mine workings in order to select an appropriate reduction method. This article presents daily measurements of nitric oxide (NO) concentrations in the workings of one of the copper ore mines owned by KGHM Polska Miedź S.A. The measurement results were used for preliminary analysis of sources of gas emissions to underground workings. The analysis is carried out through a graphical interpretation of the measured values. Knowing the details of the technological processes carried out in the mine under consideration (blasting, diesel engine machines, natural oxidation of nitrogen to NO) the graphs were interpreted by assigning individual values of NO concentrations over time to a specific t echnological process.
Self-healing of asphalt mixture: the impact of the minerals forming the aggregates in the efficiency of the heating by microwaves.
Authors: Trigos L , Gallego J , Escavy JI , Ayala D 
Published: December 2021

Abstract
The current concern for the environment and the need to reduce greenhouse gas emissions have led to new technologies related to microwave energy. One of these technologies is the self-healing of asphalt mixtures, which consists of repairing pavements through microwave application on the surface, avoiding premature road failure. Asphalt mixtures for roads are made up of more than 90% by weight of aggregates of different compositions and origins, in addition to a bituminous binder and sometimes additives. From other studies, it is known that the physical behaviour of aggregates is a function of their composition, that is, of their minerals and their proportions. Microwave heating of aggregates has proven to be an effective technique, but there are gaps in understanding how microwaves interact with aggregates and the reasons for their differential heating.
This research has studied 18 minerals that are commonly part of the rocks used as road aggregates. The objective is to identify the minerals that present the best heating rates to relate them to the differential heating of aggregates for roads. The results obtained are promising, facilitating the understanding of microwave heating of minerals. Regarding chemical composition, elements such as MgO, MnO, TiO, Al2O3, Fe2O3, and CaO (in silicate minerals) favour the heating of minerals and other elements such as SiO2 and K2O Na2O, and CaO (in carbonate minerals) retard the heating. Regarding the physical properties, density and habit of the minerals do not influence the heating, but other properties, such as the diaphaneity and the size of the crystals, influence the heating with microwaves.
Strength properties of ballast layer, created from new and recycled crushed stone ballast
Authors: Leus Oleksii , Menendez Pidal Ignacio , Kolos Aleksey , Klishch Sergei 
Published: December 2021

Abstract
The objective of the research is a railway ballast layer created from new and recycled ballast particles in different ratio. In order to study the possibility of using recycled ballast grains in ballast layer, it is necessary to carry out laboratory triaxial tests of ballast crushed stone with size of the particles 25-60 mm with different grain shape. Abrasion testing machine allows to reach the effect on new ballast, which is similar to abrasion of ballast particles in the railway track. Therefore, it is possible to create ballast samples from (new) mixed and recycled ballast and estimate which proportion has the strength characteristics, which are close to the ones in ballast layer created only with new ballast particles. The result of the study shows, that it makes sense to return the recycled crushed stone in a mix with a new one in order to reduce the cost on a railway maintenance.
Hilbert transform using a robust geostatistical method
Authors: Marashly O , Dobroka M 
Published: December 2021

Abstract
In this paper, we introduced an efficient inversion method for Hilbert transform calculation which can be able to eliminate the outlier noise. The Most Frequent Value method (MFV) developed by Steiner merged with an inversion-based Fourier transform to introduce a powerful Fourier transform. The Fourier transform process (IRLS-FT) ability to noise overthrow efficiency and refusal to outliers make it an applicable method in the field of seismic data processing. In the first part of the study, we introduced the Hilbert transform stand on a efficient inversion, after that as an example we obtain the absolute value of the analytical signal which can be used as an attribute gauge. The method depends on a dual inversion, first we obtain the Fourier spectrum of the time signal via inversion, after that, the spectrum calculated via transformation of Hilbert transforms into time range using a efficient inversion. Steiner Weights is used later and calculated using the Iterative Reweighting Least Squares (IRLS) method (efficient inverse Fourier transform). Hermite functions in a series expansion are used to discretize the spectrum of the signal in time. These expansion coefficients are the unknowns in this case. The test procedure was made on a Ricker wavelet signal loaded with Cauchy distribution noise to test the new Hilbert transform. The method shows very good resistance to outlier noises better than the conventional (DFT) method.
Image segmentation methods for quick characterization of ore chip using RGB images
Authors: Khomiak O , Benndorf J 
Published: December 2021

Abstract
The ability to forecast geometallurgical properties during resource extraction is essential to optimize the mine to mill process. Models for mine planning thus often incorporate attributes related to processability. The analysis of these attributes in a laboratory can be time- and cost intensive. Only a limited number of data may be available. During production, grade control drilling may provide access to many more samples. Conducting laboratory analysis to each of these samples would be not realistic. If there was an opportunity to quickly obtain related proxy data, as physical characteristics that can stand in for direct measurements, then these indices could be estimated, certainly less precise but with a significantly increased spatial density. A moderately simple approach to acquire data from grade control drilling is to take digital Red, Green and Blue spectral bands images (RGB images) in from core trays. Although these capture only three spectral band regions, images can contain valuable texture and colour related information. A first necessary step is to automatically extract from an image and analyse objects, that represent ore particles or mineral content. This study aims to investigate the performance of different available segmentation methods under field conditions. First an overview of methods for image segmentation as a basis to create objects is presented. Objects can be related to single grains and minerals within the grains. The aim is to provide a basis for texture feature extraction related to granular rock, such as found in chip trains. Modern image analysis provides a large number of methods for segmentation and classification of objects. This work focuses on evaluating performance on images of 3 levels of complexity of pixel- based segmentation for complex or less noisy images and object-based segmentation (Watershed, Simple Linear Iterative Clustering and Quickshift) as a more advanced and universal method.
Qualitative assessment of the complexity of the Karman vortex in the flow past double cylinders based on Shannon entropy
Authors: Jia Tao , Zhang Sen , Gao Di 
Published: December 2021

Abstract
Numerical simulations of flows past double cylinders under the conditions of different inlet velocities are carried out based on finite element methods. The phenomenon of Karman vortex is observed in the numerical study. Shannon entropy of the velocity field is calculated to quantify the complexity of the velocity field, and the time-evolution of the Shannon entropy data is analyzed by time series models of autoregressive moving average and generalized autoregressive conditional heteroskedasticity.
Free-space to single-mode fiber coupling efficiency with optical system aberration and fiber positioning error under atmospheric turbulence
Authors: Bian Yiming , Li Yan , Chen Erhu , Li Wei , Hong Xiaobin , Qiu Jifang , Wu Jian 
Published: December 2021

Abstract
Benefiting from the rapid development of fiber-optic devices, high-speed free-space optical (FSO) communication systems have recently used fiber-optic components. The received laser beam in such a system couples into single-mode fiber (SMF) at the input of the receiver module. This work is oriented to common problems in actual FSO coupling systems, such as atmospheric turbulence, optical system aberration (OSA), and fiber positioning error. We derive the statistical expectation models of SMF coupling efficiency with OSA in the presence of atmospheric turbulence and the statistical expectation models of SMF coupling efficiency with fiber positioning error in the presence of atmospheric turbulence. The influences of OSA and fiber positioning error on the coupling efficiency under different turbulence strengths are also analyzed in this paper.
The evaluation of microstructure, grain boundary character and micro texture of [Al/Si3N4/Al2O3] P nanocomposites fabricated through PM route and its influence on compressive and three-body wear properties
Authors: Kothiyal Pradeep , Joshi Amit , Mer K K S , Verma Raviraj 
Published: December 2021

Abstract
The compressive properties and 3 body wear characteristics of powder metallurgical (PM) processed [Al/Si3N4/Al2O3] P Nanocomposites with single and combined reinforcement of Al2O3 and Si3N4 reinforcing particles having different compositions (1%, 2% and 3%) were studied and evolution of microstructure, grain boundary character and micro texture of fabricated [Al/Si3N4/Al2O3] P Nanocomposites was investigated through EBSD in the present research work. The fraction of high angle boundaries (HAGBs) were observed more in combined reinforcing samples of Al2O3 and Si3N4 whereas a single reinforcing sample of Al2O3 and Si3N4 showed fewer HAGBs. Micro texture results showed the strong textures components near to {112}〈111 〉 Cu and {110}〈111 for pure sintered Al sample P and mixed reinforcement composites (M1, M2 and M3) > P whereas for single reinforcing sample showed weak textures near to transverse direction. Out of all fabricated composites, 2% mixed Al2O3 and Si3N4 reinforced composite revealed the maximum ultimate compressive strength (209.98 MPa) and least wear rate (0.1 mm3/min mm3/N-cm for 1 kg load and 3.5 mm3/N-cm for 2 kg load) attributing formation of nanocluster causing grain boundary pinning effect. The dominant failure mechanism for all samples was also detected and found to be a mixed-mode ductile failure mechanism for 2% mixed Al2O3 and Si3N4 reinforcement composite while other sample failed through ductile as well as mixed-mode mechanisms.
Effect of carbon source on the properties of dense α-SiC
Authors: Aygüzer Yaşar Zeynep , DeLucca Vincent A , Haber Richard A 
Published: December 2021

Abstract
Due to its outstanding properties, SiC is a candidate material for use in special applications such as armor. In order to use SiC in these special applications, it is necessary to produce fully dense ceramics. The ability to produce high density materials with superior performance depends on a number of factors. One of these factors is the addition of carbon to aid sintering. In this study, the effect of different carbon sources and ratios on the elastic and mechanical properties of SiC was investigated. Two types of carbon (lamp black and phenolic resin) were added to SiC in different ratios (0%–2% wt.). All samples were sintered via the spark plasma sintering (SPS) method at 1900 °C for 15 min under 50 MPa pressure. Samples made with lamp black were reached full density at 1.0 wt.%C, and the hardness and elastic modulus values were ∼22GPa and 440 GPa, respectively. While samples made with both carbon sources showed similar bulk mechanical properties, the samples made with lamp black showed more consistent microstructures. The carbon from the phonelic resin source did not appear to be as well distributed as that from the lamp black source. The results also confirmed that addition of carbon into SiC was essential to improve the density and other mechanical properties associated with it.
Thermal-cycling, simulated brushing, and beverages induced color changes and roughness of CAD/CAM poly (methyl methacrylate) denture resins
Authors: Al Taweel Sara Mohammad , Fouzan Afnan Al , Al-Otaibi Hanan N , Labban Nawaf , AlShehri Huda A 
Published: December 2021

Abstract
The aim of the present study was to evaluate and compare the effect of thermal-cycling, mechanical brushing and beverage storage on the colour changes and surface roughness of conventional heat-polymerized and CAD/CAM PMMA used to fabricate complete dentures. A total of 100 specimens measuring 10 mm in diameter and 3 mm in thickness were fabricated from conventional PMMA resin (Heat-cured, Major. Base.20, Moncalieri, Italy) and CAD/CAM blocks (Opera system, Principauté de Monaco, French). The specimens were subjected to a combined surface treatment involving thermo-cycling, mechanical brushing, and immersed in either artificial saliva (AS), coffee, tea, Coca-Cola, or lemon juice. Colour differences (ΔE) and surface roughness (Ra) was determined using a spectrophotometer and non-contact profilometer, respectively. The data were analyzed using IBM SPSS v.20 (α = 0.05). Factorial ANOVA showed that independent factors, namely material, beverages, and the interaction between independent factors, significantly influenced ΔE (F = 76.862; p < 0.001) and surface roughness (F = 71.685; p < 0.001). The overall highest and lowest colour differences was obtained for CAD/CAM PMMA (ΔE = 1.93 ± 1.29) and conventional PMMA (ΔE = 1.41 ± 1.39) resins, respectively (p = 0.061). Conventional PMMA (1.22 ± 0.20) demonstrated significantly increased roughness compared to CAD/CAM PMMA (0.91 ± 0.17) (p < 0.001). Pearson correlation showed a low degree of correlation, which was non-significant for both the PMMA (r = 0.015; p = 0.917) and C-PMMA materials (r = 0.097; p = 0.505). CAD/CAM milled PMMA resins demonstrated greater colour change and lower surface roughness compared to conventional heat-polymerized PMMA resins. Specimens in tea and coffee demonstrated maximum colour changes and were perceivable by the human eye. On the contrary, specimens immersed in low pH acidic beverages namely Coca-Cola and lemon juice demonstrated maximum surface roughness.
Compressive mechanical behavior and model of composite elastic-porous metal materials
Authors: Yang Pei , Zhou Tao , Jia Di , Qin Zhiqiang , Wu Yiwan , Bai Hongbai 
Published: December 2021

Abstract
This work presents the experimental characterization and theoretical modeling of composite elastic-porous metal materials (C-EPMM). C-EPMM is a novel porous metallic damping material made of wire mesh and wire helix. A series of quasi-static compressive experiments were carried out to investigate the stiffness and energy absorption ability of the C-EPMM with different mass ratios. The experimental results show that the mass ratios can significantly affect the stiffness and loss factor of C-EPMM. To efficiently predict the nonlinear mechanical properties of the C-EPMM a theoretical model of C-EPMM was proposed for the first time, the model was based on the manufacturing process. A comparison between the predicted data and the experimental data was conducted. The results show that the theoretical model can accurately predict the mechanical performance of C-EPMM. The conclusions derived from this work can provide a new method for adjusting the mechanical performance of EPMM in applications.
A Monte Carlo study of different LET definitions and calculation parameters for proton beam therapy
Authors: Smith Edward A K , Winterhalter Carla , Underwood Tracy S A , Aitkenhead Adam H , Richardson Jenny C , Merchant Michael J , Kirkby Norman F , Kirby Karen J , Mackay Ranald I 
Published: December 2021

Abstract
The strong in vitro evidence that proton Relative Biological Effectiveness (RBE) varies with Linear Energy Transfer (LET) has led to an interest in applying LET within treatment planning. However, there is a lack of consensus on LET definition, Monte Carlo (MC) parameters or clinical methodology. This work aims to investigate how common variations of LET definition may affect potential clinical applications. MC simulations (GATE/GEANT4) were used to calculate absorbed dose and different types of LET for a simple Spread Out Bragg Peak (SOBP) and for four clinical PBT plans covering a range of tumour sites. Variations in the following LET calculation methods were considered: (i) averaging (dose-averaged LET (LETd) & track-averaged LET); (ii) scoring (LETd to water, to medium and to mass density); (iii) particle inclusion (LETd to all protons, to primary protons and to particles); (iv) MC settings (hit type and Maximum Step Size (MSS)). LET distributions were compared using: qualitative comparison, LET Volume Histograms (LVHs), single value criteria (maximum and mean values) and optimised LET-weighted dose models. Substantial differences were found between LET values in averaging, scoring and particle type. These differences depended on the methodology, but for one patient a difference of ∼100% was observed between the maximum LETd for all particles and maximum LETd for all protons within the brainstem in the high isodose region (4 keV μm−1 and 8 keV μm−1 respectively). An RBE model using LETd including heavier ions was found to predict substantially different LET-weighted dose compared to those using other LET definitions. In conclusion, the selection of LET definition may affect the results of clinical metrics considered in treatment planning and the results of an RBE model. The authors’ advocate for the scoring of dose-averaged LET to water for primary and secondary protons using a random hit type and automated MSS.