bluuebunny/crossref_metadata_2025 huggingface dataset:
3D image compression during ultrasound phased diagnostics based on wavelet subband coding planar scans
Authors: Bekhtin Y S , Vorobyev K M
Published: December 2021

The proposed compression method is based on the application of a two-dimensional discrete fast wavelet transform (FWT) to planar scans of 3D ultrasound images in order to simultaneously reduce redundancy and suppress speckle at a fixed quota of bits. The main idea of the method is to fuse three rules for threshold processing the wavelet coefficients of the scans, uniform and non-uniform quantizers, and bit quota distributions over subbands of the scan FWT based on the proposed cost function. The simulation results have shown that at the encoding rate of up to 1 bit/pixel, the quantity of artefacts were decreased up to 5-7 % of the original quantity under a signal-to-speckle ratio more than 16 dB, and the structural similarity index (SSIM) increased to 0.94-0.97 for defects of rectangular, triangular and oval shapes. The paper also presents the results proving the effectiveness of the proposed method in comparison with some variants of the solution according to the scheme “pre-filtering + codec”.
Cloud species classification from video recordings
Authors: Egorov D P , Kutuza B G , Akvilonova A B , Kravchenko O V
Published: December 2021

Large data bank of images has been accumulated during atmospheric cloudinessground-based observations from 2017 to 2020 near Fryazino city, Moscow Region. The problemof obtained images classification into several types is considered. The types are clear sky (noclouds); cumulus cloudiness of various extent (humilis, mediocris, congestus); very powerfulclouds such as cumulonimbus or nimbostratus; stratus cloud cover; stratocumulus clouds; lightand high-positioned clouds (altocumulus, cirrus, cirrostratus and cirrocumulus). A qualitativeanalysis of the key features of gray, blue, green and red level co-occurrence matrices for variouspixel distances and directions (angles) is performed to solve the problem. An image classification algorithm based on these and other key features retrieved during image preprocessingis developed. The quality evaluation is performed. The developed software tool is currentlysuccessfully used for atmospheric radiometry problems support.
Application of spectral analysis methods for data pre-processing of anomaly detection problem of vibration diagnostics in non-destructive testing
Authors: Trufanov N N , Churikov D V , Kravchenko O V
Published: December 2021

The paper is devoted to the problem of primary data processing obtained in the vibration measurements during the processing of the workpiece on a milling machine with computer numerical control. An experimental setup is described and an algorithm for analysing vibration diagnostics signals using a mathematical machine learning tool is proposed. Special attention is paid to the study of the rigidity characteristics of the machine at different relative positions of its components. The analysis of the equipment design and factors affecting the ongoing process is carried out, as a result of which the received signal is processed and its characteristic fragments in the time and frequency domains are identified. The data is prepared for further use in solving the problem of detecting anomalies of the technological process, which implies predicting the progress of the technological process based on a mathematical model constructed using machine learning methods, and identifying deviations of the real technological process from the forecast. Preliminary preparation is carried out using the windowed Fourier transform. Various variants of windows in the transformation are considered, including those constructed using atomic functions. Calculations are performed using the Python 3.9 language, the main results are supported by graphs. The development of training methods for the considered models of neural networks is the subject of further research.
Optical system of 3D AOTF-based microscopic imager
Authors: Naumov A A
Published: December 2021

In this paper, we propose a novel approach of calculating optical stereoscopic systems containing acousto-optic tunable filters. Each channel is designed separately as a simple imaging system. It is formed by an entrance lens, a radiation receiver lens, and an acousto-optic filter. The optimization of the depth of field and the magnification of the optical system is carried out during the calculations. The numerical values of the overall parameters obtained satisfy the given initial requirements. The Zemax simulation of the built optical system is in strong agreement with the calculation.
Polarization stability of the single-mode laser diodes radiation applied in radiation scattering study complexes
Authors: Parshin V A , Bliznyuk V V , Dolgov A V
Published: December 2021

Key features of semiconductor lasers and its serially manufacturing technology modernization have greatly expanded of its using at applied studies at last 20 years. But there is set of factors restricting such lasers application in a number of optical-electronic measuring complexes. Particularly in particle image velocimetry (PIV) and laser Doppler velocimetry (LDV) complexes commonly the gas and solid-state lasers is used due to more stability of spectral, energy and polarization characteristics of radiation then semiconductor lasers have. However gradual introduction of the serially manufacturing laser diodes into such systems picking up the pace that certainly characterizes the progress of reaching the required stability of its output laser radiation parameters. In laser measurement systems where medium investigation carried out by analyzing of scattering radiation in it the probe radiation polarization is often important. So the using in such systems the laser diodes as sources of radiation need to be followed by stability monitoring of its polarization characteristics which may be violated both by the outer factors and by natural degradation of inner laser diode structure. This work is devoted to the issues of monitoring the radiation polarization characteristics of the serially manufacturing single-mode laser diodes.
Raman random lasing in Ba(NO3)2 powder
Authors: Shevchenko M A , Baranov A N , Kudryavtseva A D , Maresev A N , Tcherniega N V , Umanskaya S F , Vodchits A I , Zemskov K I
Published: December 2021

Random lasing in Raman active material – barium nitrate powder – has been registered in two temporal regimes: nanosecond and picosecond. Stimulated Raman scattering (SRS) in Ba(NO3)2 for picosecond excitation has been shown to have much lower threshold and spectrum containing more components than for nanosecond excitation opposite to the case of a bulk medium. In picosecond regime SRS intensity increased with temperature decreasing and redistributed in favor of the higher order components. SRS pulse duration in picosecond regime was estimated to be in the range 16.5-22 ps. High conversion efficiency of SRS in barium nitrate powder in picosecond regime and its larger stability under laser impact than for bulk samples gives possibility to use it as an active material in Raman converters.
Optical diagnostics of railway rail defects
Authors: Poroykov A Yu , Sharikova M O , Marchenkov A Yu , Barat V A
Published: December 2021

The safety of rail transport, including passenger traffic, largely depends on the timely diagnosis of the state of the rail infrastructure. To determine the state of metal structures, the method of acoustic emission (AE) is used. It is based on the registration of elastic mechanical vibrations arising in the material of the controlled object from a defect. The AE method is highly informative, but the interpretation of measurement results often causes difficulties, especially when studying complex structural elements. In this paper, it is proposed to use the digital image correlation (DIC) method to study the defects of railway rails using the acoustic emission method. Visualization of defects using the DIC method will make it possible to better interpret the results of inspection by the acoustic emission method and to establish the relationship between the size of defects and the parameters of AE pulses.
Development of ultrasound echocardiography technique for imaging of the cardiovascular system of small organisms in vivo
Authors: Machikhin A S , Zykova L A , Burlakov A B , Titov S A , Bogachenkov A N , Huang C C
Published: December 2021

A technique based on a high-frequency ultrasound scanner was developed for imaging and characterization of the cardiovascular system of small organisms in vivo. An optical microscope combined with the ultrasonic unit was used in the experimental setup for simultaneous recording ultrasonic signals and video data. It was shown that combination of optical and ultrasonic data is effective to visualize dynamic processes in a living object. In addition to imaging of the cardiovascular system, video data was processed to estimate the period and phase of the cardiac cycle and to generate a trigger signal for the ultrasonic unit. The proposed approach and developed experimental setup were applied to imaging of the Danio rerio larva. In a result of the processing of the synchronous ultrasonic and optical data, the blood flow in the heart of the larva and the movement of surrounding organs were observed.
Classification of human skin Raman spectra using multivariate curve resolution (MCR) and partial least squares discriminant analysis (PLS-DA)
Authors: Matveeva I , Khristoforova Y , Moryatov A , Myakinin O , Bratchenko I , Kozlov S , Zakharov V
Published: December 2021

The main purpose of the paper is classification of the human skin Raman spectra using partial least squares discriminant analysis (PLS-DA) into classes depending on the disease. In vivo Raman spectra of normal skin, basal cell carcinoma, malignant melanoma and pigmented nevus are considered. A feature of the approach is the analysis not of the Raman spectra themselves, but of the concentrations of the eight most significant spectra components identified using multivariate curve resolution (MCR). As a result, the ROC curve was calculated and the optimal classification threshold was chosen. The accuracy of the classification models ranged from 63.3 to 86.7%, depending on the model. The findings suggest that this approach could also be useful for classification of specific diseases.
High-performance 1×4 - demultiplexer for next-generation all-optical telecommunication systems
Authors: Vytovtov K A , Barabanova E A , Vishnevsky V M
Published: December 2021

In this paper the new 1×4 optical demultiplexer for next-generation all-optical switching systems is proposed. The controlled mirrors are the main elements of this device. The control voltage for this mirror is generated by a rectenna from an optical control signal. In according to operation principle this optical signal enters the system simultaneously with an information signal. The analytical approach of calculation energy losses in the demultiplexer based on the translation matrix method is proposed. And also the analytical method of performance calculation is offered for the first time. First of all, the delay time due the transient mode in the power supply circuit is found. The equivalent electrical scheme of the optical demultiplexer is proposed for the first time. Note that the theoretical results obtained in this work can be used for analysing various controlled optical devices. The numerical calculations in accordance to the presented methods are carried out also.
Design of thermal imaging continuous-zoom optical system
Authors: Kryukov A V , Kachurin Yu Yu , Datiy Yu S
Published: December 2021

The report tells about the design of a middle wave infrared continuous-zoom imaging optical system. To capture the image in an «eye-type» infrared optical system a multi-element sensor is used. To increase the contrast of the thermal image the sensor is equipped with a cold aperture. The use of an optical system based on the continuous-zoom lens makes it possible to solve the problems of object detection and identification more effectively but requires taking into account some features of varifocal lenses. The optical system being analyzed in the report includes front zoom objective system and secondary imaging system. The front zoom optical system is composed of four groups and provides the focal length that is continuously changed with a large zoom ratio (15–20X) under the condition of a constant total length of the system. The secondary imaging system is designed for zoom system exit stop and sensor cold stop conjugation. The design technique represents analytical expressions and equations to obtain optical parameters of the front and secondary system components and the motion curves for movable groups.
Helium isotope studies of the Central Tien Shan
Authors: Polyak B G , Bataleva E A , Rybin A K
Published: December 2021

The research shows new results of isotope-helium studies carried out in the Tien Shan - Naryn and Atbashi basins. Sampling of thermal mineral springs in the Eastern Tien Shan was carried out in order to identify traces of mantle emanations in fluids and to assess the degree of permeability of the Earth’s crust for the introduction of deep masses, which would make it possible to clarify the nature of the interaction of the crust and mantle in the zone of recent orogeny. Concentrations of helium isotopes were measured in gas and water samples from 6 thermal mineral springs in the Central Tien Shan. It was found that fluids from three sources contain an abnormally high amount of mantle helium. In the gases of the Narzan source, the ratio3He/4He in the gas phase (597÷600) × 10−8reaches the Central Asian maximum found earlier on the Fergana ridge in the Kyzyl-Beles source (510÷630) × 10−8. The obtained results support the ideas on the existence of two sublatitudinal positive helium isotope anomalies on the northern and southern flanks of the Eastern Tien Shan - in the zones of junction of the epiplatform neoorogene with more ancient tectonically stable structures.
The magnitude of the transverse contraction of the Middle Tien Shan along the “Karabuk” profile at the late orogenic stage
Authors: Przhiyalgovskii E S
Published: December 2021

The detailed geological profile “Karabuk” constructed in recent years, crossing the triad of alpine structures “Naryn Depression - Baibichetoo Uplift - Atbashi Depression [[CHECK_DOUBLEQUOT_ENT]] in the central part of Tien Shan, provides new material for studying the style and parameters of deformations at the late phase of the Indian - Eurasian plate collision. Using original methodological techniques and in accordance with the basic principles of balanced sections method, the horizontal deformation of the rock complex of the Cenozoic sedimentary cover (a meridional reduction in the width of the orogenic belt) was determined, starting from the end of the Neogene. Variations in the thickness of the cover layers determined during the research were taken into account. The presented tectonic reconstruction demonstrates the structure of a single Naryn-Atbashi sedimentary basin before the intense deformations at the late orogenic phase. It is significant, that the magnitude of deformations on individual segments of the profile differs markedly. The cover of the Atbashi depression is more deformed, its width has decreased by 6 km (about 17%) in this section, while the borders of the wider Naryn depression have converged by only 3.7 km (8%). The total South-North contraction of the NBA system measured by us during the Cenozoic is about 10 km (12% of its original width). The values of the contraction from south to north (the horizontal component of the deformation) obtained by us compared with the values given by other researchers.
Convergence of daily mean coordinates of precise positioning methods
Authors: Kenigsberg D V , Salamatina Yu M , Prokhorov O A , Kuzikov S I
Published: December 2021

As part of the research of modern movements of the Earth’s crust, an analysis of 7 high-precision methods for calculating GNSS positions was carried out for the convergence of their daily mean coordinates. Based on Euclidean distances, regular and maximal discrepancies between coordinates of different methods are given. According to the coordinates in the ITRF, 5 methods are stood out with regular coordinate discrepancies <1 mm, and individual maximum discrepancies up to 30 mm. The other two methods have regular discrepancies in coordinates up to 2 cm, and the maximum differences reach 1 m. For a group of stations global coordinates transformation into a local reference frame leads to the effect of coordinate stabilization and increases their relative precision in the time series. As a result of such procedure, the level of maximum coordinate discrepancies between the methods decreased to 46%. Moreover, one of the methods of calculating coordinates has improved its convergence with the other methods by 80%. Based on the Euclidean distance method, the quality of the raw data for each station was evaluated. Thus, there is a group of 8 stations, for which the convergence of coordinates in different methods are approximately at the same level, and 2-3 times better than for the other 2 stations.
Extended isolation forest – application to outlier detection in geomagnetic data
Authors: Imashev S A
Published: December 2021

The aim of this study is to present a method for detection of outliers in the time series of total intensity of geomagnetic field using Extended Isolation Forest algorithm. The method is consisted of three steps: 1) generation of additional features that take into account the regular daily variation and smooth behaviour of normal data, 2) detection of potential outliers based on ensemble of extended isolating trees and 3) subsequent refinement based on difference between the outlier and its replacement with interpolated value. Application of the method for detection of outliers in yearly time series of the total geomagnetic field at Ak-Suu and Kegety stations showed that the algorithm identifies both global and contextual outliers. Average classification metrics for the method are characterized as high and have the following values: precision 94.3%, recall 93.9% and F-score 94.5%, and probabilities of errors of the first and second kind are comparable to similar algorithms used for detection of outliers in magnetograms of different sampling rate.
Geoelectrical structure and monitoring in fault zones of Uimon depression in Gorny Altai region using electromagnetic methods
Authors: Nevedrova N N , Sanchaa A M , Shaparenko I O
Published: December 2021

In this paper we present the results of our studies of sections of the Uimon basin in Gorny Altai (Russia) using a complex of electrical prospecting methods. The areas of Baratal Formation at the surface have been investigated. This areas explored in order to understand the stages of formation of the depression. In addition, the possibilities of the electrotomography method for regular observations in seismoactive regions are shown. Comparison of the amplitudes of the resistivity variations based on repeated ERT measurements in different zones of the Terekta fault indicates the activity of its eastern part, which is expressed in significant resistivity variations exceeding 100%. At the same time, the variations in the northwestern part of the fault, reaching 15% on average, are many times smaller.
Refinement of the seismicity of construction sites for high-rise buildings
Authors: Kamchybekov M , Murataliev N , Kamchybekov Y
Published: December 2021

The development of the construction of high-rise residential buildings requires a separate approach, depending on the engineering and geological conditions of the site for seismic microzoning. There are not only engineering sectors but also large premises that will serve as business offices and technical centers in the underground part of high-rise buildings. In this regard, the foundation of the building goes to great depth. The influence of soil conditions at the level of abutment of the buildings’ foundation can be determined with seismic microzoning. As a result, the task of clarifying the projected construction site in construction is currently relevant. It includes the refinement of the seismic intensity of the construction site during the construction of high-rise buildings, which are located in different multilayer soil types.
Recurrence of earthquakes in the area of the Toktogul HPP cascade
Authors: Ts Manzhikov B
Published: December 2021

A brief statistical analysis of the current seismicity of the Toktogul region of the Kyrgyz Republic is done. The analysis concerns the region where the Toktogul HPP cascade on the Naryn River is located, and covers the period from 1973 to 2021 years. The space-time distributions of earthquakes, accumulation characteristics, probability and recurrence of seismic events of various magnitudes are considered. According to the analysis results, the maximum magnitude of seismic events in the Toktogul region can be ∼ 7.4, and the recurrence period of earthquakes with a magnitude of M ≥ 7 and above T ≥ 10 years is equal.
Modified data on geoeffective solar flares and seismic noise variations
Authors: Sycheva N A , Bogomolov L M
Published: December 2021

The problem of the relationship between strong magnetic swarms caused by solar flares and variations in seismicity is considered. The data on the temporal dependences of the parameters of seismic noise (average level, and standard deviation, RMS) recorded by the stations of the KNET seismic network have been used as the output data of monitoring the territory of the Bishkek geodynamic proving ground (Northern Tien Shan). The signatures of the influence of a magnetic swarm that occurred after an ultra-strong solar flare on September 6, 2017 have been established. The results obtained on the increase in seismic noise after this super-strong eruptive event are consistent with the results of studies on the influence of magnetic swarms on changes in regional seismicity.
Application of the soft starter for the asynchronous motor of the belt conveyor
Authors: Dmitrieva V V , Sizin P E , Sobyanin A A
Published: December 2021

The purpose of the work is to justify the need for a smooth start of the conveyor belt. Based on the technological features of the transportation process, the direct start of the conveyor with a loaded undercarriage entails an increase in inertial forces, overload of the traction chains and the drive. Due to the increased starting torque, there is a danger of slipping, the occurrence of an oscillatory transient of the escaping branch of the tape, slipping between the tape and the drive drum. This leads to significant wear of the tape and breakdowns of other equipment, which requires high repair costs. With a smooth start of the conveyor, the acceleration lasts longer, but the movement of the concentrated masses of the belt is more consistent, less oscillatory, which indicates less dynamic forces in the belt. Also, with a smooth start, energy losses in the engine and its heating are reduced. The main results of the work - the transients in the currents of the stator and rotor, in the speed of rotation of the motor and in the speed of movement of the conveyor belt were obtained. The developed model allows us to investigate the dynamic operating modes of the engine and the mechanical part of the conveyor, to analyze the forces arising in the belt during direct and smooth start of the conveyor, to evaluate the slip of the belt and the magnitude of the traction factor. Conclusions - the results of this work should be the basis for controlling the tension in the belt and maintaining the traction factor of the conveyor belt in the start-brake operating modes. In addition, the results obtained can be used in the development of a belt speed control system depending on the amount of random freight traffic entering the conveyor.
Improvement of reagent flotation modes of sphalerite and pyrite from deposits of copper-zinc pyrite, polymetallic copper-zinc pyrite and polymetallic ores
Authors: Kyaw Z Y , Tiagalieva Z A , Htet Z O , Phyo K K
Published: December 2021

Copper-zinc pyrite (Sulphide) and polymetallic ores of Russia are complex and difficult to process mineral raw materials. The main technology for the enrichment of this ores are flotation. Currently, the improvement of the flotation technology of this mineral raw materials is carried out in several way. It has been established by the practice of beneficiation of copper-zinc ores that obtaining high-quality zinc and pyrite concentrates is impossible without adding flotation modifiers of sphalerite and pyrite to various flotation operations. This reagent are copper (II) sulfates, zinc and iron (II) sulfates in an alkaline calcareous medium. Therefore, studies on the flotation of sphalerite and pyrite in an alkaline calcareous medium with the addition of one of these metal sulfates to the mineral flotation operation were performed. The effect of each copper (II) sulfates zinc, and iron (II) on the flotability of sphalerite and pyrite was studied during flotation of the mineral and xanthate and dithiophosphate at pH = 8, 10, and 12. The aim of this work was to study the effect of the flotation size class (- 0.074 + 0.044 mm) sphalerite and pyrite of one of the Russian deposits by sulfhydryl collectors in the presence of copper, zinc and iron sulfates in the liquid phase of flotation pulp
Dynamics of glass windows in mining vehicles under the impacts of rock pieces: numerical and analytical comparison for computational models validation
Authors: Sukhanova O , Larin O , Ziętek B
Published: December 2021

This study represents the results of linear dynamics analysis of glass plates subjected to rock pieces impacts occurring in underground machines’ windows. The aim of the work is to provide analytical and numerical solutions, obtain frequencies and plate displacement, and compare results of stress calculation for different models. The work performs finite element method (FEM) computations within a modal analysis in 3D statement including a mesh-size convergence analysis. Given approach is a basement for estimation of safety work conditions for operators in cabins of underground mining vehicles when glass windows are subjected to rock bursts and damages.
Employing the digital platform for control system development in a coal mining enterprise
Authors: Nepsha Fedor , Varnavskiy Kirill , Voronin Vyacheslav , Ermakov Alexandr , Kostomarov Roman
Published: December 2021

The article discusses the issues related with a digital platform for distributed energy resources in the framework of mining enterprises. The paper examines the directions of sustainable development of the infrastructure of a mining enterprise, among which it is necessary to highlight the use of digital twins, taking into account the relationship of technological processes with the processes of transport of electrical energy, the development of small generation and the use of renewable energy sources. The authors proposed a two-level architecture of a coal mine control system, the implementation of which is possible with the introduction of IoT devices. It includes the EDGE layer and the Cloud / on-premise layer, which implement the corresponding functions. In the future, such a control system will make it possible to implement the concept of unmanned mining with the effective use of machine learning methods. In conclusion, it was noted that it is important to ensure the synergy of the developed platform solutions in the electric power industry and the mining industry to reduce the total costs of creating digital mining enterprises and step-by-step implementation of the Industry 4.0 concept.
Detection of a predefined acoustic pattern by a measurement system on a drone and its application to search for a missing man in an underground mine
Authors: Zimroz Paweł , Wróblewski Adam , Trybała Paweł
Published: December 2021

Due to the very difficult working conditions and a certain number of hazards that do not occur in other industries, the operation of rescue units in underground mines is necessary. The area of exploitation is usually very large, thus determining the location of a person, which may be in need due to the accident, is not an easy task. As the time for reaching such a person is crucial, there is a strong need for a solution that would provide a quick establishment of the victims’ location. Moreover, conducting a rescue mission is always associated with risk exposure for rescuers’ life and health. Thus, in this paper, we propose a solution based on an unmanned aerial vehicle (UAV) for a predefined acoustic pattern detection to support rescue units in human location assessment in the underground mine. The presented method is based on measuring the dissimilarity between the subsequent short-time power spectra and the referential spectrum characterizing the UAV’s ego-noise. This relatively general and data-driven approach is applied both to generated narrowband harmonic patterns and to the human voice. As the analyzed signals of interest are of specific frequency content they can be selected from the background noise with the use of band-pass filtering.
Gross alpha and gross beta activities measurements in groundwaters using liquid scintillation counting (LSC)
Authors: Kowalska A , Maciejewski P , Szczęśniewicz M
Published: December 2021

In this work Authors describe the methodology of gross alpha and gross beta activities determination in water samples. The chosen method is dedicated to LSC and is based on ISO 11704:2018 and it is suitable for ground waters with low and medium salinity, especially drinking or tap waters as well as medicinal waters (with healing properties, using in health resorts). Authors describe the proper sampling, laboratory preparation including radon removal and measurements conditions. The local and European law regulations showing the limits of radioactivity of drinking waters and medicinal waters are presented. This work presents also selected data of gross alpha and gross beta activities from selected research: the highest levels is measured in Jordanian (gross alpha) and in Brazil (gross beta) and it is respectively 3.58 Bq/L and 5.22 Bq/L.
Counting trees - methods of automatic analysis of photogrammetric data in forests of the continental region
Authors: Budnik K , Byrtek J , Kapusta A
Published: December 2021

The paper is devoted to the methods of automatic analysis of photogrammetric data in forests of the continental region. It also discusses how automatic tree counting can be used to manage forests. Experimental research was conducted to verify two methods: Faster R-CNN and Template Matching to automatically detecting tree objects in the continental region characterized by mixed forests with a large predominance of conifers. The research was done based on photogrammetric data taken in four areas belonging to forest districts subordinate to the Regional Directorate of State Forests in Zielona Góra. Data was collected from drones and small airplanes with a photogrammetric container. The results show that both methods can be used for analyzes in specific cases. Moreover, the level of Recall shows the advantage of Faster R-CNN methods for the photogrammetric data collected during the flights in various weather conditions.
Review of vegetation indices for studies of post-mining processes
Authors: Pawlik M , Rudolph T , Benndorf J , Blachowski J
Published: December 2021

Each phenomenon has its cause and effect. During the research on the post-mining processes, the reasons can be found in ongoing processes taking place after the end of the mining exploitation. Therefore, a very important aspect is Geomonitoring. Currently, the post-mining processes taking place all over the world, should be considered into two groups of processes: such taking place in subsurface regions and such on the surface on the Earth. Through an integrated Geomonitoring it is possible to observe, among others, the vegetation of the mining areas. The observation of the state of vegetation is an aspect of research using remote sensing methods, e.g. indicators of vegetation. Of course, the reduction of plant vegetation may be caused by other reasons as well. Therefore, an important aspect is to distinguish changes in vegetation resulting affects coming from natural factors (climate changes, long-term droughts or sudden weather phenomena) and the resulting from post-mining processes. This article presents the indicators that have been discovered and used in the research of plant vegetation, which can be used in the post-mining.
LiDAR-based Simultaneous Localization and Mapping in an underground mine in Złoty Stok, Poland
Authors: Trybała P
Published: December 2021

The mining sector is one of the most promising areas for implementing advanced autonomous robots. The benefits of increased safety, robot actions’ repeatability, and reducing human presence in hazardous locations are especially important in underground mines. One of the core functionalities of such a device is the robot’s ability to localize and navigate itself in the working environment. To achieve this, simultaneous localization and mapping (SLAM) techniques are used. In selected cases, they also allow the acquisition of dense spatial data in the form of 3D point clouds, which can be utilized for various 3D modeling and spatial analysis purposes. In this work, a mobile robot, equipped only with a compact laser scanner, is used to acquire spatial data in the adit of a closed mine in Zloty Stok, Poland. This data is further processed with selected SLAM algorithms to create a homogeneous 3D point cloud. Results are visualized and compared to a model obtained with a survey-grade laser scanner. Accuracy evaluation shows that employing SLAM algorithms to process data collected by a mobile robot can produce a reasonably accurate 3D geometrical model of an underground tunnel, even without incorporating any additional sensors.
A thermogelling organic-inorganic hybrid hydrogel with excellent printability, shape fidelity and cytocompatibility for 3D bioprinting
Authors: Hu Chen , Ahmad Taufiq , Haider Malik Salman , Hahn Lukas , Stahlhut Philipp , Groll Jürgen , Luxenhofer Robert
Published: December 2021

Alginates are the most commonly used bioink in biofabrication, but their rheological profiles make it very challenging to perform real 3D printing. In this study, an advanced hybrid hydrogel ink was developed, a mixture of thermogelling diblock copolymer, alginate and clay i.e. Laponite XLG. The reversible thermogelling and shear thinning properties of the diblock copolymer in the ink system improves handling and 3D printability significantly. Various three-dimensional constructs, including suspended filaments, were printed successfully with high shape fidelity and excellent stackability. Subsequent ionic crosslinking of alginate fixates the printed scaffolds, while the diblock copolymer is washed out of the structure, acting as a fugitive material/porogen on the (macro)molecular level. Finally, cell-laden printing and culture over 21 d demonstrated good cytocompatibility and feasibility of the novel hybrid hydrogels for 3D bioprinting. We believe that the developed approach could be interesting for a wide range of bioprinting applications including tissue engineering and drug screening, potentially enabling also other biological bioinks such as collagen, hyaluronic acid, decellularized extracellular matrices or cellulose based bioinks.
Dual-working mode device based on dual-element photonic crystal-stepped concave waveguide
Authors: Li Zizheng , Wang Jianping , Chen Hongyao , Lu Huimin , Zhu Yifan , Bai Bing
Published: December 2021

In this study, a Si3N4 on insulator device used for photonic integrated circuits (PICs) is proposed. The dual-working mode device is constructed using a racetrack microring resonator, which is established using a dual-element photonic crystal-stepped concave waveguide. A novel scheme of dual-working modes is realized, and sensing and filtering are performed simultaneously without interference. The results show that a sensitivity of 29 pm K−1 and a line width of 0.28 nm are obtained for the sensor mode. An extinction of 41.8 dB and bandwidth of up to 305.5 nm are achieved in the filter mode. The footprint of the entire device is within 20 μm × 11 μm, which is ultra-compact and suitable for PICs.
Influence of light polarization state on the imaging quality of dark-field imaging system
Authors: Chen Dan , Wang Yuqin , Zhang Rongzhu
Published: December 2021

Annular linear polarized light is used as the illumination source of a reflective dark-field detection system in this paper. According to the theories of the bidirectional reflectance distribution function and multi-beam interference, the influence of the light polarization state on the intensity distribution of the scattered light is analyzed in detail. For surface defects, a simulation model of dark-field imaging is established based on the finite-difference time-domain method. Both the near-field and the far-field scattering intensity distributions caused by surface defects are calculated under different illumination conditions. The incidence angle and polarization state of the illuminated light are optimized. Simulation and experimental results show that the image quality will be minimally affected by the interference effect, while P-polarized light illuminates with an incident angle of 45°. The higher measurement accuracy of the dark-field imaging detection system can be obtained when the optimized illumination scheme is used.
Fried’s coherence length measurement of dynamic Kolmogorov type turbulence using the autocorrelation function
Authors: Lekshmi S R , Naik Dinesh N , Narayanamurthy C S
Published: December 2021

A new method to find the Fried’s coherence length of a dynamic Kolmogorov type turbulence in a laboratory environment is reported in this paper. This method utilises the autocorrelation function obtained from the quantitative characteristics of a rotating pseudo random phase plate in one of the arms of a Mach–Zehnder interferometer. Theoretical formalism and experimental verification are presented.
The tribological performance of W-DLC in solid–liquid lubrication system addivated with Cu nanoparticles
Authors: Li Dongshan , Kong Ning , Li Ruishan , Zhang Boyang , Zhang Yongshun , Wu Zhiguo , Zhang Qingdong
Published: December 2021

Judicious selection of additives having chemical and physical compatibility with the DLC films may help improving the triboligical properties and durability life of DLC-oil composite lubrication systems. In this study, Cu nanoparticles were added to PAO6 base oil to compose a solid-liquid composite lubrication system with W-DLC film. The effects of nanoparticle concentration, test temperature and applied load on tribological performance were systematically studied by a ball-on-disk friction test system. The tribological results illustrated that Cu nanoparticles could lower the coefficient of friction (COF) and dramatically reduce the wear rates of W-DLC films. The optimal tribological behavior was achieved for the 0.1 wt% concentration under 30 °C and the applied load of 100 N. The test temperature and applied load were vital influencing factors of the solid–liquid lubrication system. The bearing effect and soft colloidal abrasive film of spherical Cu nanoparticle contributed to the excellent tribological performance of the composite lubrication system under mild test conditions, meanwhile, the local delamination of W-DLC film and oxidation were the main causes of the friction failure under harsh test conditions. With test temperature and applied loads increase the degree of graphitization of the W-DLC film increased. In conclusion, there are several pivotal factors affecting the tribological performance of solid–liquid lubrication systems, including the number of nanoparticles between rubbing contact area, graphitization of the worn W-DLC films, tribofilms on the worn ball specimens and oxidation formed in friction test, and the dominant factor is determined by the testing condition.
Experimental analysis of surface finishing properties in magnetically assisted abrasive finishing of ASTM B16 brass
Authors: Singh Palwinder , Singh Lakhvir
Published: December 2021

Magnetically assisted abrasive finishing (MAAF) presents an attractive concept of surface and edge finishing by fine magnetic abrasive particles (MAPs). This study aims to contribute an experimental evaluation of the effect of process parameters viz. magnetic field density (MFD), circumferential speed of workpiece, and abrasive grit size on the surface finishing properties in MAAF when experiments were performed for finishing pipes of ASTM B16 brass material with the sintered MAPs. The developed model is based on the obtained experimental data accompanied by Box- Behnken design (BBD) of response surface methodology (RSM) analysis. Apart from deciding significant parameters, this analysis also presents the modeling of finishing properties and optimizes the desired performance parameters. Analysis of variance (ANOVA) includes data of standard deviation, coefficient of determination (R2), adjusted, and predicted (R2). MFD and speed show a significant effect on both the responses viz. surface roughness improvement rate (SRIR) and material removal rate (MRR). Analysis has shown that abrasive grit size is the most dominant parameter towards SRIR followed by MFD. The maximum SRIR of 88.12% (minimum Ra 50 nm) and 4.28 mg min−1 is achieved through multi-objective optimization with 0.8 T MFD, 500 rpm speed, and 300 μm grit size. The mathematical models of SRIR and MRR were also developed using RSM, focusing on varying MFD, speed, and grit size which can be used to predict the desired surface finishing properties. The model generated for SRIR, and MRR has an error of 0.204% and 2.506% respectively. Further SEM images were taken to understand the surface appearance of the finished surface.
PLGA-based drug delivery system for combined therapy of cancer: research progress
Authors: Ruirui Zhang , He Jian , Xu Ximei , Li Shengxian , Peng Hongmei , Deng Zhiming , Huang Yong
Published: December 2021

In recent years, PLGA micro/nano particle drug delivery systems has been widely used in cancer treatment. According to the unique properties of PLGA, carriers of various structures are designed to keep the function of drugs or bioactive substances, ensure the effective load of molecules and improve the bioavailability of drugs in diseased parts. PLGA is one of the earliest and most commonly used biodegradable materials. It is often used for functional modification with other polymers (such as polyethylene glycol and chitosan) or other molecules (such as aptamers and ligands) to deliver various small molecule drugs (such as DOX and DTX) and bioactive macromolecules (such as proteins and nucleic acids) to improve targeting, controlled release and therapeutic properties. In this paper, the preparation methods, physical and chemical properties and medical applications of PLGA micro/nano particles are discussed. We focused on the recent research progress of the PLGA-based drug carrier system in tumor combination therapy.
Quantum yield optimization of carbon dots using response surface methodology and its application as control of Fe3+ion levels in drinking water
Authors: Alkian Ilham , Sutanto Heri , Hadiyanto
Published: December 2021

Early detection of heavy metals in drinking water is a fundamental step that must be taken to prevent adverse effects on health. This research aims to develop a heavy metal ion detector by utilizing the fluorescence properties of carbon dots. Cdots were synthesized using the microwave irradiation method based on the central composite design: urea mass 0.31–3.68 gr; reactor power 200–1000 W; synthesis time is 13–46 min, and the response is quantum yield. Material characterization includes PL, TEM, UV-VIS, XRD, and FTIR. The selectivity and sensitivity of Cdots as detectors were tested for Ag+, Bi3+, Ni2+, Al3+, Co2+, Pb2+, Fe3+, Zn2+, Zr4+, and Hg2+ ions at concentrations of 0–10 μM. The results showed that Cdots were successfully synthesized by fluorescent light green at 544 nm. An adequate response model is quadratic with the formulation QY = +58.36 + 10.41X1 + 14.06X2 +13.59X3–5.57X2X3–4.89X1
2−8.60X2
2–5.40X3
2. The best Cdots were obtained in the formulation of R9 (3 g, 800 W, 40 min), which resulted in a QY of 74.39%. The characteristics of Cdots are spherical, diameter 6.6 nm, the bandgap of 2.53 eV, and having an amorphous structure. The surface of Cdots contains various functional groups such as O–H, C–H, C=O, C–N, and C=C. In the heavy metal detection test, Cdots showed specific sensitivity to Fe3+ ions. The addition of Fe3+ concentration and the extinction of Cdots fluorescence intensity formed a linear correlation F0/F = 0.08894[Fe3+]+0.99391 (R2 = 0.99276). The detection ability of Cdots for Fe3+ ions reaches a concentration of 0.016 ppm, much lower than the regulatory threshold limit of SNI, WHO, and IBWA. The detection of Fe3+ ions in drinking water uses a fluorescence technique consistent with the SSA and ICP-OES. Based on these results, the fluorescence technique using Cdots can be an instrument for quality control of the final drinking water product.
Bias-voltage dependent operational characteristics of a fully spectroscopic pixelated cadmium telluride detector system within an experimental benchtop x-ray fluorescence imaging setup
Authors: Moktan Hem , Panta Raj Kumar , Cho Sang Hyun
Published: December 2021

Commercially available fully spectroscopic pixelated cadmium telluride (CdTe) detector systems have been adopted lately for benchtop x-ray fluorescence (XRF) imaging/computed tomography (XFCT) of objects containing metal nanoprobes such as gold nanoparticles (GNPs). To date, however, some important characteristics of such detector systems under typical operating conditions of benchtop XRF/XFCT imaging systems are not well known. One important but poorly studied characteristic is the effect of detector bias-voltage on photon counting efficiency, energy resolution, and the resulting material detection limit. In this work, therefore, we investigated these characteristics for a commercial pixelated detector system adopting a 1-mm-thick CdTe sensor (0.25-mm pixel-pitch), known as HEXITEC, incorporated into an experimental benchtop cone-beam XFCT system with parallel-hole detector collimation. The detector system, operated at different bias-voltages, was used to acquire the gold XRF/Compton spectra from 1.0 wt% GNP-loaded phantom irradiated with 125 kVp x-rays filtered by 1.8-mm Tin. At each bias-voltage, the gold XRF signal, and the full-width-at-half-maximum at gold Kα
2 XRF peak (∼67 keV) provided photon counting efficiency and energy resolution, respectively. Under the current experimental conditions, the detector photon counting efficiency and energy resolution improved with increasing bias-voltage by ∼41 and ∼29% at −300V; ∼54 and ∼35% at −500V, respectively, when compared to those at −100V. Consequently, the GNP detection limit improved by ∼26% at −300V and ∼30% at −500V. Furthermore, the homogeneity of per-pixel energy resolution within the collimated detector area improved by ∼34% at −300V and ∼54% at −500V. These results suggested the gradual improvements in the detector performance with increasing bias-voltage up to −500V. However, at and beyond −550V, there were no discernible improvements in photon counting efficiency and energy resolution. Thus, the bias-voltage range of −500 to −550V was found optimal under the current experimental conditions that are considered typical of benchtop XRF/XFCT imaging tasks.