Applied sciences

Bulletin of the Polish Academy of Sciences: Technical Sciences

Content

Bulletin of the Polish Academy of Sciences: Technical Sciences | Early Access |

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Abstract

In this paper, thermal oxidation resistance of silicide-coated niobium substrates was tested in a temperature range of 1300–1450°C using an HVOF burner. Pure niobium specimens were coated using the pack cementation CVD method. Three different silicide thickness coatings were deposited. Thermal oxidation resistance of the coated niobium substrates was tested in a temperature range of 1300–1450°C using an HVOF burner. All samples that passed the test showed their ability to stabilize the temperature over a time of 30 s during the thermal test. The rise time of substrate temperature takes about 10 s, following which it keeps constant values. In order to assess the quality of the Nb-Si coatings before and after the thermal test, light microscopy, scanning electron microscopy (SEM) along with chemical analysis (EDS), X-ray diffraction XRD and Vickers hardness test investigation were performed. Results confirmed the presence of substrate Nb compounds as well as Si addition. The oxygen compounds are a result of high temperature intense oxidizing environment that causes the generation of SiO phase in the form of quartz and cristobalite during thermal testing. Except for one specimen, all substrate surfaces pass the high temperature oxidation test with no damages.
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Authors and Affiliations

Radosław Szklarek
Tomasz Tański
Bogusław Mendala
Marcin Staszuk
Łukasz Krzemiński
Paweł Nuckowski
Kamil Sobczak
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Abstract

In this scientific publication, research results of two newly developed hot-rolled Fe-Mn-Al-C (X105) and Fe-Mn-Al-Nb-Ti-C (X98) types of steel were compared. These types of steel are characterized by an average density of 6.68 g/cm³, a value 15% lower compared to conventional structural steel. Hot rolling was carried out on a semi-industrial line to evaluate the effect of hot plastic deformation conditions with different cooling variants on the structure. The detailed analysis of phase composition as well as microstructure allows us to state that the investigated steel is characterized by an austenitic-ferritic structure with carbides precipitates. The results of the transmission electron microscopy (TEM) tests of both types of steel after hot rolling showed the occurrence of various deformation effects such as shear bands, micro bands, and lens twins in the microstructure. Based on the research undertaken with the use of transmission electron microscopy, it was found that the hardening mechanism of the X98 and X105 steel is deformation-induced plasticity by the formation of shear bands (SIP) and micro shear bands (MBIP).
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Authors and Affiliations

Liwia Sozańska-Jędrasik
Wojciech Borek
Janusz Mazurkiewicz
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Abstract

S304H steel is used in the construction of pressure components of boilers with supercritical operating parameters. The paper presents the results of research on the microstructure following ageing for 30,000 hours at 650 and 700°C. Microstructure examination was performed using scanning and transmission electron microscopy. The precipitates were identified using transmission electron microscopy. The paper analyses the precipitation process and its dynamics depending on the temperature and ageing time in detail. MX carbonitrides and the ε_Cu phase were proved to be the most stable phase, regardless of the test temperature. It was also showed that the M₂₃C₆ carbide precipitates in the tested steel and the intermetallic sigma phase (σ) may play a significant role in the loss of durability of the tested steel. This is related to their significant increase due to the influence of elevated temperature, and their coagulation and coalescence dynamics strongly depend on the ageing/operating temperature level. The qualitative and quantitative identification of the secondary phase precipitation processes described in the study is important in the analysis of the loss of durability of the tested steel under creep conditions.
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Authors and Affiliations

Adam Zieliński
Robert Wersta
Marek Sroka
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Abstract

The growing interest in one-dimensional tin oxide-based nanomaterials boosts research on both high-quality nanomaterials as well as production methods. This is due to the fact that they present unique electrical and optical properties that enable their application in various (opto)electronic devices. Thus, the aim of the paper was to produce ceramic SnO₂ nanowires using electrospinning with the calcination method, and to investigate the influence of the calcination temperature on the morphology, structure and optical properties of the obtained material. A scanning electron microscope (SEM) and Fourier-transform infrared spectroscopy (FTIR) were used to examine the morphology and chemical structure of obtained nanomaterials. The optical properties of manufactured one-dimensional nanostructures were investigated using UV-Vis spectroscopy. Moreover, based on the UV-Vis spectra, the energy band gap of the prepared nanowires was determined. The analysis of the morphology of the obtained nanowires showed that both the concentration of the precursor in the spinning solution and the calcination temperature have a significant impact on the diameter of the nanowires and, consequently, on their optical properties.
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Authors and Affiliations

Tomasz Tański
Weronika Smok
Wiktor Matysiak
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Abstract

Magnesium alloys have recently become increasingly popular in many sectors of the industry due to their unique properties, such as low density, high specific strength, vibration damping ability along with their recyclability and excellent machinability. Nowadays, thin films have been attracting more attention in applications that improve mechanical and corrosion properties. The following alloys were used for the coated Mg-Al-RE and the ultra-light magnesium-lithium alloy of the Mg-Li-Al-RE type. A single layer of TiO2 was deposited using the atomic layer deposition ALD method. Multiple layers of the Ti/TiO₂ and Ti/TiO₂/Ti/TiO₂ type were obtained by the MS-PVD magnetron sputtering technique. Samples were investigated by scanning and a transmission electron microscope (SEM, TEM) and their morphology was studied by an atomic forces microscope (AFM). Further examinations, including electrochemical corrosion, roughness and tribology, were also carried out. As a result of the research, it was found that the best electrochemical properties are exhibited by single TiO2 layers obtained by the ALD method. Moreover, it was found that the Ti/TiO₂/Ti/TiO₂ double film has better properties than the Ti/TiO₂ film.
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Authors and Affiliations

Marcin Staszuk
Łukasz Reimann
Aleksandra Ściślak
Justyna Jaworska
Mirosława Pawlyta
Tomasz Mikuszewski
Dariusz Kuc
Tomasz Tański
Antonín Kříž
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Abstract

Magnesium-based alloys are widely used in the construction, automotive, aviation and medical industries. There are many parameters that can be modified during their synthesis in order to obtain an alloy with the desired microstructure and advantageous properties. Modifications to the chemical composition and parameters of the synthesis process are of key importance. In this work, an Mg-based alloy with a rare-earth element addition was synthesized by means of mechanical alloying (MA). The aim of this work was to study the effect of milling times on the Mg-based alloy with a rare-earth addition on its structure and microhardness. A powder mixture of pure elements was milled in a SPEX 8000D high energy shaker ball mill under an argon atmosphere using a stainless steel container and balls. The sample was mechanically alloyed at the following milling times: 3, 5, 8 and 13 h, with 0.5 h interruptions. The microstructure and hardness of samples were investigated. The Mg-based powder alloy was examined by means of X-ray diffraction (XRD), scanning electron microscopy (SEM) and using a Vickers microhardness test. The results showed that microhardness of the sample milled for 13 h was higher than that of those with milling time of 3, 5 and 8 h.
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Authors and Affiliations

Sabina Lesz
Bartłomiej Hrapkowicz
Klaudiusz Gołombek
Małgorzata Karolus
Patrycja Janiak
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Abstract

Magnesium-based materials constitute promising alternatives for medical applications, due to their characteristics, such as good mechanical and biological properties. This opens many possibilities for biodegradable materials to be used as less-invasive options for treatment. Degradation is prompted by their chemical composition and microstructure. Both those aspects can be finely adjusted by means of proper manufacturing processes, such as mechanical alloying (MA). Furthermore, MA allows for alloying elements that would normally be really hard to mix due to their very different properties. Magnesium usually needs various alloying elements, which can further increase its characteristics. Alloying magnesium with rare earth elements is considered to greatly improve the aforementioned properties. Due to that fact, erbium was used as one of the alloying elements, alongside zinc and calcium, to obtain an Mg₆₄Zn₃₀Ca₄Er₁ alloy via mechanical alloying. The alloy was milled in the SPEX 8000 Dual Mixer/Mill high energy mill under an argon atmosphere for 8, 13, and 20 hours. It was assessed using X-ray diffraction, energy dispersive spectroscopy and granulometric analysis as well as by studying its hardness. The hardness values reached 232, 250, and 302 HV, respectively, which is closely related to their particle size. Average particle sizes were 15, 16, and 17 μm, respectively
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Authors and Affiliations

Bartłomiej Hrapkowicz
Sabina Lesz
Marek Kremzer
Małgorzata Karolus
Wojciech Pakieła
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Abstract

This paper investigates the preparation of silicon nitride composites with multi-walled carbon nanotubes (MWCNTs). Samples containing 1–10 wt% MWCNTs were ultrasonically processed in non-aqueous suspensions, dried, pressed, and then subjected to non-pressure sintering at 1600 °C for 2 h. The preliminary results showed that the mixture of activated silicon nitride and covered MWCNTs could be sintered. The porosity of the obtained samples ranged from 0.27 to 36.94 vol.%. The microstructure was observed by scanning electron microscopy (SEM), and the mechanical properties (hardness and fracture toughness) were also determined. Good hardness values were obtained for samples prepared by sintering the mechanically activated precursor under a flowing nitrogen atmosphere using the lowest fraction of CNTs. Residual activator reduced the densification of the composites.
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Authors and Affiliations

Marta Mikuśkiewicz
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Abstract

The main aim of the study was to search for the relationship between the anisotropy of the structure of polyfurfuryl alcohol (PFA) – polymer/compressed expanded graphite (CEG)-matrix composites at subsequent stages of the technological process and characteristics of the acoustic emission (AE) descriptors. These composites, obtained after successive technological procedures of impregnation, polymerization, and carbonization, possess different structure, densities, porosity, and other physicochemical properties. In the structures of composites prepared on the basis of CEG, two basic directions can be distinguished: parallel to the bedding plane of graphite sheets and perpendicular to it. The measurements were carried out for the stress acting in these two main directions. The investigation has shown that the AE method enables the detection of anisotropy in the structure of materials. The results of the research show that all four of the acoustic emission descriptors studied in this work are sensitive to the technological stages of these materials on the one hand and their structure anisotropy on the other. Fourier analysis of the recorded spectra provides interesting conclusions about the structural properties of composites as well as a lot of information about the bonding forces between the carbon atoms of which the CEG matrix is composed and the PFA polymer or turbostratic carbon.
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Authors and Affiliations

Sylwia Berdowska
Janusz Berdowski
Aubry Frederic
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Abstract

This research presents an experimental study carried out for the modeling and optimization of some technological parameters for the machining of metallic materials. Certain controllable factors were analyzed such as cutting speed, depth of cut, and feed per tooth. A dedicated research methodology was used to obtain a model which subsequently led to a process optimization by performing a required number of experiments utilizing the Minitab software application. The methodology was followed, and the optimal value of the surface roughness was obtained by the milling process for an aluminum alloy type 7136-T76511. A SECO cutting tool was used, which is standard in aluminum machining by milling. Experiments led to defining a cutting regime that was optimal and which shows that the cutting speed has a significant influence on the quality of the machined surface and the depth of cut and feed per tooth has a relatively small impact on the chosen ranges of process parameters.
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Authors and Affiliations

Aurel Mihail Țîțu
Alina Bianca Pop
Marcin Nabiałek
Camelia Cristina Dragomir
Andrei Victor Sandu
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Abstract

The rod specimens were produced from Pr9Fe50 + xCo13Zr1Nb4B23 – x (x = 0, 5, 8) alloys using the suction-casting technique. Subsequent devitrification annealing of those samples resulted in the change of their phase structure and magnetic properties. For annealed specimens of all investigated compositions, the Rietveld analyses of X-ray diffractions have shown the presence of three crystalline phases: the hard magnetic Pr2Fe11.2Co2.8B, soft magnetic α-Fe, and paramagnetic Pr1 + xFe4B4, which have precipitated within the amorphous matrix. This technique allowed us to determine the weight fractions of constituent phases. Furthermore, the microstructural changes with the alloy composition were observed. Magnetic measurements of annealed rods allowed us to calculate the switching field distributions (SFD) and δM plots in order to determine the strength and character of magnetic interactions between grains of constituent phases.
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Authors and Affiliations

Katarzyna Pawlik
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Abstract

Tensile tests of 8009Al alloy reinforced with SiC and Al₂O₃ particles fabricated by powder metallurgy (PM) were conducted at temperatures of 250–350°C and strain rates of 0.001–0.1 s⁻¹. The ultimate tensile strength and yield strength of the samples decreased while the temperature and strain rate increased. The elongation slightly decreased at first and then increased with growing temperature because of the medium-temperature brittleness of the alloy matrix. When the strain rate was 0.1 s⁻¹, the elongation of the 8009Al/Al₂O₃ composites always decreased with an increase in temperature because of the poorly coordinated deformation and weak bonding between the matrix and Al₂O₃ particles at such a high strain rate. The work-hardening rates of the composites sharply increased to maxima and then decreased rapidly as the strain increased. Meanwhile, the 8009Al/SiCₚ composites displayed superior UTS, YS, elongation, and work-hardening rates than those of the 8009Al/Al₂O₃ composites under the same conditions. Compared to 8009Al alloys reinforced with spherical Al₂O₃ particle, 8009Al alloys reinforced with irregular SiC particles exhibited a better strengthening effect. The fracture mechanism of the 8009Al/SiCₚ composites was mainly ductile, while that of the 8009Al/Al₂O₃ composites was primarily debonding at the matrix–particle interfaces in a brittle mode.
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Authors and Affiliations

Shuang Chen
Guoqiang Chen
Pingping Gao
Chunxuan Liu
Anru Wu
Lijun Dong
Zhonghua Huang
Chun Ouyang
Hui Zhang
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Abstract

The increasing demand for electricity and global attention to the environment has led energy planners and developers to explore developing control techniques for energy stability. The primary objective function of this research in an interconnected electrical power system to increase the stability of the system with the proposed RRVR technique is evaluated in terms of the different constraints like THD (%), steady-state error (%), settling time (s), overshoot (%), efficiency (%) and to maintain the frequency at a predetermined value, and controlling the change of the power flow of control between the areas renewable energy generation (solar, wind, and fuel cell with battery management system) based intelligent grid system. To provide high-quality, reliable and stable electrical power, the designed controller should perform satisfactorily, that is, suppress the deviation of the load frequency. The performance of linear controllers on non-linear power systems has not yet been found to be effective in overcoming this problem. In this work, a fractional high-order differential feedback controller (FHODFC) is proposed for the LFC problems in a multi-area power system. The gains of FHODFC are best adjusted by resilience random variance reduction technique (RRVR) designed to minimize the overall weighted absolute error performance exponential time. Therefore, the controller circuit automatically adjusts the duty cycle value to obtain a desired constant output voltage value, despite all the grid system’s source voltage and load output changes. The proposed interconnected multi-generation energy generation topology is established in MATLAB 2017b software.
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Authors and Affiliations

B. Prakash Ayyappan
R. Kanimozhi
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Abstract

Self-healing grids are one of the most developing concepts applied in electrical engineering. Each restoration strategy requires advanced algorithms responsible for the creation of local power systems. Multi-agent automation solutions dedicated for smart grids are mostly based on Prim’s algorithm. Graph theory in that field also leaves many problems unsolved. This paper is focused on a variation of Prim’s algorithm utility for a multi-sourced power system topology. The logic described in the paper is a novel concept combined with a proposal of a multi-parametrized weight calculation formula representing transmission features of energy delivered to loads present in a considered grid. The weight is expressed as the combination of three elements: real power, reactive power, and real power losses. The proposal of a novel algorithm was verified in a simulation model of a power system. The new restoration logic was compared with the proposal of the strategy presented in other recently published articles. The novel concept of restoration strategy dedicated to multi-sourced power systems was verified positively by simulations. The proposed solution proved its usefulness and applicability.
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Authors and Affiliations

Artur Łukaszewski
Łukasz Nogal
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Abstract

In the paper we propose a fractional-piecewise-constant-order PID controller and discuss the stability and robustness of a closed loop system. In stability analysis we use the transform method and include the Nyquist-like criteria. Simulations for designed controllers are performed for the second-order plant with a delay.
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Authors and Affiliations

Piotr Oziablo
Dorota Mozyrska
Malgorzata Wyrwas
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Abstract

The paper presents the main issues of the management of electrical grids. Selected information technology tools supporting electrical grids maintenance are presented. In electrical infrastructure maintenance of power companies, geographic information systems are increasingly used to support the management of their resources. Their functionalities in terms of creating comprehensive databases for the electrical infrastructure of the power sector are described. The important information technology tools regarding spatial systems for supporting maintenance and operation management electrical grids and the conditions of their implementation are presented. This paper also attempts to present an innovative multidimensional evaluation of the technical and economic benefits resulting from the use of modern information technology tools for the management of energy infrastructure.
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Authors and Affiliations

Waldemar Kamrat
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Abstract

This paper considers the problem of the accurate task space finite-time control susceptible to both undesirable disturbance forces exerted on the end-effector and unknown friction forces coming from joints directly driven by the actuators as well as unstructured forces resulting from the kinematic singularities appearing on the mechanism trajectory. We obtain a class of estimated extended transposed Jacobian controllers which seem to successfully counteract the external disturbance forces on the basis of a suitably defined task-space non-singular terminal sliding manifold (TSM) and the Lyapunov stability theory. Moreover, in order to overcome (or to minimise) the undesirable chattering effects, the proposed robust control law involves the second-order sliding technique. The numerical simulations (closely related to an experiment) ran for a mobile manipulator consisting of a non-holononic platform of (2;0) type and a holonomic manipulator of two revolute kinematic pairs show the performance of the proposed controllers and make a comparison with other well-known control schemes.
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Authors and Affiliations

Mirosław Galicki
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Abstract

This paper investigates the non-fragile event-triggered control of positive switched systems with random nonlinearities and controller perturbations. The random nonlinearities and controller perturbations are assumed to obey Bernoulli and Binomial sequence, respectively. A class of linear event-triggering conditions is introduced. A switched linear co-positive Lyapunov function is constructed for the systems. For the same probability with respect to nonlinearities and controller perturbations in each subsystem, a non-fragile controller of positive switched systems is designed in terms of linear programming. Then, the different probability case is considered and the corresponding non-fragile event-triggered control is explored. Finally, the effectiveness of theoretical findings is verified via two examples.
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Authors and Affiliations

Yanqi Wu
Junfeng Zhang
Shizhou Fu
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Abstract

The paper analyzes the operation of innovative composite measurement instrumentation for spontaneous electromagnetic emission. The designed receiver measures and records both components of the EM field emitted by rocks subjected to increased mechanical stress. The range of signals transmitted by the receiver system and its dynamics were determined. A receiver was used to observe electromagnetic signals generated during a hard coal sample crushing in laboratory conditions. Test results confirmed the high dynamic range of the system at 98 dB and the ability to observe signals over a range of frequencies up to 50 kHz. The experimental results confirm the signal bandwidth characteristic of coal mine EM field emission obtained in earlier studies. The constructed autonomous receiver can be used in mine workings as a complementary warning system for emerging mine hazards.
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Authors and Affiliations

Remigiusz Mydlikowski
Krzysztof Maniak
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Abstract

In this paper, design, construction and switching parameters of a self-made optical shutter with scalable aperture were reported. The aim of the study was to obtain the shortest possible switching times, minimum shutter open time and comparable with commercial shutter, the switch-on and switch-off times. For this purpose, numerical simulations were performed using Comsol Multiphysics 5.4. The design of the shutter and the control system have been optimized accordingly to the obtained results of numerical simulations. The optimized design was fabricated in a professional mechanical workshop and operational parameters of the constructed device were investigated. The switching parameters of the shutter, such as opening time, closing time, minimum shutter open time and other parameters were measured. The values of the parameters were determined from a statistical analysis of a sample consisting of 10,000 measurement results. The performed characterization showed that the tested device has the opening time of 0.8 ms, while the closing time is approximately 1 ms. The designed device is characterized by the minimum shutter open time of 6.4 ms.
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Authors and Affiliations

Piotr Pokryszka
Mateusz Wosko
Wojciech Kijaszek
Regina Paszkiewicz
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Abstract

All universities are responsible for assessing the quality of education. One of the required factors is the results of the students’ research. The procedure involves, most often, the preparation of the questionnaire by the staff, which is voluntarily answered by students; then, the university staff uses the statistical methods to analyze data and prepare reports. The proposed EQE method by the application of the fuzzy relations and the optimistic fuzzy aggregation norm may show a closer connection between the students’ answers and the achieved results. Moreover, the objects obtained by the application of the EQE method can be visualized by using the t-SNE technique, cosine between vectors and distances of points in five-dimensional space.
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Authors and Affiliations

Grzegorz Śmigielski
Aleksandra Mreła
Oleksandr Sokolov
Mykoła Nedashkovskyy
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Abstract

Developing novel methods, approaches and computational techniques is essential for solving efficiently more and more demanding up-to-date engineering problems. Designing durable, light and eco-friendly structures starts at the conceptual stage, where new efficient design and optimization tools need to be implemented. Nowadays, apart from the traditional gradient-based methods applied to optimal structural and material design, innovative techniques based on versatile heuristic concepts, like for example Cellular Automata, are implemented. Cellular Automata are built to represent mechanical systems where the special local update rules are implemented to mimic the performance of complex systems. This paper presents a novel concept of flexible Cellular Automata rules and their implementation into topology optimization process. Despite a few decades of development, topology optimization still remains one of the most important research fields within the area of structural and material design. One can notice novel ideas and formulations as well as new fields of their implementation. What stimulates that progress is that the researcher community continuously works on innovative and efficient topology optimization methods and algorithms. The proposed algorithm combined with an efficient analysis system ANSYS offers a fast convergence of the topology generation process and allows obtaining well-defined final topologies.
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Authors and Affiliations

Katarzyna Tajs-Zielińska
Bogdan Bochenek
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Abstract

The paper contains a description of the geometry of Beveloid gears. It describes the distribution of forces in a Beveloid gear with a straight tooth line and a helical tooth line. The paper presents research on the experimentally determined parameters of transmission operation, including the sound pressure level and the amount of heat emitted during operation. The design and construction of the test stand were presented. The research methodology was described. Operational tests are carried out on household appliances with Beveloid gears: Grinder and Jam mixer. Thanks to an appropriately selected narrowing angle, estimated values of service life extension of the above-mentioned transmissions are given.
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Authors and Affiliations

Piotr Strojny
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Abstract

Specific emitter identification (SEI) can distinguish single-radio transmitters using the subtle features of the received waveform. Therefore, it is used extensively in both military and civilian fields. However, the traditional identification method requires extensive prior knowledge and is time-consuming. Furthermore, it imposes various effects associated with identifying the communication radiation source signal in complex environments. To solve the problem of the weak robustness of the hand-crafted feature method, many scholars at home and abroad have used deep learning for image identification in the field of radiation source identification. However, the classification method based on a real-numbered neural network cannot extract In-phase/Quadrature (I/Q)-related information from electromagnetic signals. To address these shortcomings, this paper proposes a new SEI framework for deep learning structures. In the proposed framework, a complex-valued residual network structure is first used to mine the relevant information between the in-phase and orthogonal components of the radio frequency baseband signal. Then, a one-dimensional convolution layer is used to a) directly extract the features of a specific one-dimensional time-domain signal sequence, b) use the attention mechanism unit to identify the extracted features, and c) weight them according to their importance. Experiments show that the proposed framework having complex-valued residual networks with attention mechanism has the advantages of high accuracy and superior performance in identifying communication radiation source signals.
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Authors and Affiliations

Lingzhi Qu
Junan Yang
Keju Huang
Hui Liu
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Abstract

3D scanning measurements are gaining popularity every year. Quick inspections on already captured point clouds are easy to prepare with the use of modern software and machine learning. To achieve repeatability and accuracy, some surface and measurement issues should be considered and resolved before the inspection. Large numbers of manufacturing scans are not intended for manual correction. This article is a case study of a small surface inspection of a turbine guide vane based on 3D scans. Small surface errors cannot be neglected as their incorrect inspection can result in serious faults in the final product. Contour recognition and deletion seem to be a rational method for making a scan inspection with the same level of accuracy as we have now for CMM machines. The main reason why a scan inspection can be difficult is that the CAD source model can be slightly different from the inspected part. Not all details are always included, and small chamfers and blends can be added during the production process, based on manufacturing standards and best practices. This problem does not occur during a CMM (coordinate measuring machine) inspection, but it may occur in a general 3D scanning inspection.
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Authors and Affiliations

Marcin Jamontt
Paweł Pyrzanowski
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Abstract

The application of micro components in various fields such as biomedical, medical, automobile, electronics, automobile and aviation significantly improved. To manufacture the micro components, different techniques exist in the non-traditional machining process. In those techniques, electrochemical micromachining (ECMM) exhibits a unique machining nature, such as no tool wear, non-contact machining process, residual stress, and heat-affected zone. Hence, in this study, micro holes were fabricated on the copper work material. The sodium nitrate (NaNO₃) electrolyte is considered for the experiments. During the experiments, magnetic fields strength along with UV rays are applied to the electrolyte. The L₁₈ orthogonal array (OA) experimental design is planned with electrolyte concentration (EC), machining voltage (MV), duty cycle (DC) and electrolyte temperature (ET). The optimization techniques such as similarity to ideal solution (TOPSIS), VlseKriterijumska Optimizacija I Kompromisno Resenje (VIKOR) and grey relational analysis (GRA) were employed to find the optimal parameter combinations. The entropy weight method is used to assess the weight of responses such as MR and OC. The optimal combination using TOPSIS, VIKOR and GRA methods shows the same results for the experimental runs 8, 9 and 7, and the best optimal parameter combination is 28 g/l EC, 11 V MV, 85 % DC and 37°C ET. Based on the analysis of variance (ANOVA) results, electrolyte concentration plays a significant role by contributing 86 % to machining performance. The second and least contributions are DC (3.86 %) and ET (1.74 %) respectively on the performance. Furthermore, scanning electron microscope (SEM) images analyses are carried out to understand the effect of magnetic field and heated electrolyte on the work material.
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Authors and Affiliations

K.G. Saravanan
R. Thanigaivelan
M. Soundarrajan
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Abstract

Diagnostic methodologies are of fundamental importance for operational strategies of electrical devices, both in the power grid and in industrial applications. This paper reports about a novel approach based on partial discharge analysis applied to high voltage electrical insulation. Especially dynamics of charges deposited by partial discharges is explored applying a chopped sequence. The applications refer to microvoids occurring inside solid insulating systems or at the interfaces, such as delaminations at the electrodes. The experiments were carried out on embedded voids having distinctive wall dielectric materials. The underlying physical phenomena of post discharge charge transport are analyzed. The assessment is performed using phase-resolved partial discharge patterns acquired applying a chopped sequence. The chopped partial discharge (CPD) method provides quantitative insight into post discharge charge decay processes due to deposited and accumulated charges fluctuations. The assessment indicator is based on comparing partial discharge inception angle between chopped sequence and continuous run. The experiments have shown that materials with distinctive surface conductivity revealed adequately different charge decay time dynamics. The detailed analysis yields time constant of walls charge decay for insulating paper equal to 12 ms and cross-linked polyethylene 407 ms. The CPD method may be further used to investigate streamer physics inside bounded cavities in the form of voids. The presented method provides a quantitative approach for charge non-invasive decay assessment and offers high potential in future diagnostics applications.
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Authors and Affiliations

Marek Florkowski
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Abstract

The rotating machines with overhung rotors form a wide class of devices used in many types of industry. For this kind of rotor machines in the paper there is investigated an influence of dynamic and static unbalance of a rotor, parallel and angular misalignments of shafts as well as inner anisotropy of rigid couplings on system dynamic responses. The considerations are performed by means of a hybrid structural model of the machine rotor-shaft system, which consists of continuous beam finite elements and discrete oscillators. Numerical calculations are carried out for parameters characterizing a heavy blower applied in the mining industry. The main goal of the research is to assess a sensitivity of the above-mentioned imperfections on excitation severity of rotor-shaft lateral vibrations and on motion stability of the machine in question.
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Authors and Affiliations

Tomasz Szolc
Robert Konowrocki
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Abstract

A gyroscopic rotor exposed to unbalance is studied and controlled with an active piezoelectrical bearing in this paper. A model is required in order to design a suited controller. Due to the lack of related publications utilizing piezoelectrical bearings and obtaining a modal model purely exploiting experimental modal analysis, this paper reveals a method to receive a modal model of a gyroscopic rotor system with an active piezoelectrical bearing. The properties of the retrieved model are then incorporated into the design of an originally model-free control approach for unbalance vibration elimination, which consists of a simple feedback control and an adaptive feedforward control. After the discussion on the limitations of the model-free control, a modified controller using the priorly identified modal model is implemented on an elementary rotor test-rig comparing its performance to the original model-free controller.
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Authors and Affiliations

Jens Jungblut
Christian Fischer
Stephan Rinderknecht
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Abstract

Rotors of rotating machines are often mounted in hydrodynamic bearings. Loading alternating between the idling and full load magnitudes leads to variation of the rotor journal eccentricity in the bearing gap. To avoid taking place of undesirable operating regimes, its magnitude must be kept in a certain interval. This is offered by the hydrodynamic bearings lubricated with smart oils, the viscosity of which can be changed by action of a magnetic field. A new design of a hydrodynamic bearing lubricated with magnetically sensitive composite fluid is presented in this paper. Generated in the electric coil, the magnetic flux passes through the bearing housing and the layer of lubricant and then returns back to the coil core. Action of the magnetic field on the lubricant affects the fluid apparent viscosity and thus position of the rotor journal in the bearing gap. The developed mathematical model of the bearing is based on application of the Reynolds equation that has been adapted for the case of lubricants exhibiting the yielding shear stress. The results of the performed simulations confirmed that the change of magnetic induction makes it possible to change the bearing load capacity and thus to keep the rotor journal eccentricity in the required range. The extent of control has its limitations. High increase in the loading capacity can arrive at the loss of stability of the rotor forced vibration and at inducing oscillation of large amplitude.
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Authors and Affiliations

Jaroslav Zapoměll
Petr Ferfecki
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Abstract

In this paper, a new application of the Numerical Assembly Technique is presented for the balancing of linear elastic rotor-bearing systems with a stepped shaft and arbitrarily distributed mass unbalance. The method improves existing balancing techniques by combining the advantages of modal balancing with the fast calculation of an efficient numerical method. The rotating stepped circular shaft is modelled according to the Rayleigh beam theory. The Numerical Assembly Technique is used to calculate the steady-state harmonic response, eigenvalues and the associated mode shapes of the rotor. The displacements of a simulation are compared to measured displacements of the rotor-bearing system to calculate the generalized unbalance for each eigenvalue. The generalized unbalances are modified according to modal theory to calculate orthogonal correction masses. In this manner, a rotor-bearing system is balanced using a single measurement of the displacement at one position on the rotor for every critical speed. Three numerical examples are used to show the accuracy and the balancing success of the proposed method.
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Authors and Affiliations

Georg Quinz
Marcel S. Prem
Michael Klanner
Katrin Ellermann
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Abstract

Vibration in rotating machinery leads to a series of undesired effects, e.g. noise, reduced service life or even machine failure. Even though there are many sources of vibrations in a rotating machine, the most common one is a mass unbalance. Therefore, a detailed knowledge of the system behavior due to mass unbalance is crucial in the design phase of a rotor-bearing system. The modelling of the rotor and mass unbalance as a lumped system is a widely used approach to calculate the whirling motion of a rotor-bearing system. A more accurate representation of the real system can be found by a continuous model, especially if the mass unbalance is not constant and arbitrarily oriented in space. Therefore, a quasi-analytical method called Numerical Assembly Technique is extended in this paper, which allows for an efficient and accurate simulation of the unbalance response of a rotor-bearing system. The rotor shaft is modelled by the Rayleigh beam theory including rotatory inertia and gyroscopic effects. Rigid discs can be mounted onto the rotor and the bearings are modeled by linear translational/rotational springs/dampers, including cross-coupling effects. The effect of a constant axial force or torque on the system response is also examined in the simulation.
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Authors and Affiliations

Michael Klanner
Marcel S. Prem
Katrin Ellermann
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Abstract

The analysis of subsonic stall flutter in turbomachinery blade cascade is carried out using a medium fidelity reduced order aeroelastic numerical model. The model is type of field mesh free approach and based on a hybrid boundary element method. The medium fidelity flow solver is developed on the principle of viscous-inviscid two way weak coupling approach. The hybrid flow solver is employed to model separated flow and stall flutter in the 3D blade cascade at subsonic speed.The aerodynamic damping coefficient w.r.t. inter blade phase angle in traveling wave mode is estimated along with other parameters. The same stability parameter is used to analyze the cascade flutter resistance regime.The estimated results are validated against experimental measurements as well as Navier-Stokes based high fidelity CFD model. The simulated results show good agreement with experimental data. Furthermore, the hybrid flow solver has managed to bring down the computational cost significantly in compared to field based CFD models.Therefore, all the prime objectives of the research have been successfully achieved.
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Authors and Affiliations

Chandra Shekhar Prasad
Pavel Šnábl
Luděk Pešek
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Abstract

Full floating ring bearings are state of the art at high speed turbomachinery shafts like in turbochargers. Their main feature is an additional ring between shaft and housing leading to two fluid films in serial arrangement. Analogously, a thrust bearing with an additional separating disk between journal collar and housing can be designed. The disk is allowed to rotate freely only driven by drag torques, while it is radially supported by a short bearing against the journal. The paper at hand addresses these kind of thrust bearing and its implementation into a transient rotor dynamic simulation by solving the Reynolds PDE online during time integration. Special attention is given to the coupling between the different fluid films of this bearing type. Finally, the differences between a coupled and an uncoupled solution are discussed.
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Authors and Affiliations

Steffen Nitzschke
Christian Ziese
Elmar Woschke
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Abstract

This paper deals with research studies of the magnetic bearing control systems for a high-speed rotating machine. Here, theoretical and experimental characteristics of the control systems with the Model Algorithmic Control (MAC) algorithm and the proportional-derivative (PD) algorithm are presented. The MAC algorithm is the non-parametric predictive control method that uses an impulse response model. A laboratory model of the rotor-bearing unit under study consists of two active radial magnetic bearings and one active axial (thrust) magnetic bearing. The control system of the rotor position in air gaps consists of the fast prototyping control unit with a signal processor, the input and output modules, power amplifiers, contactless eddy current sensors and the host PC with a dedicated software. Rotor displacement and control current signals were registered during investigations using a data acquisition (DAQ) system. In addition, measurements were performed for various rotor speeds, control algorithms and disturbance signals generated by the control system. Finally, the obtained time histories are presented, analysed and discussed in this paper.
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Authors and Affiliations

Paulina Kurnyta-Mazurek
Tomasz Szolc
Maciej Henzel
Krzysztof Falkowski
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Abstract

This paper addresses the problem of part of speech (POS) tagging for the Tamil language, which is low resourced and agglutinative. POS tagging is the process of assigning syntactic categories for the words in a sentence. This is the preliminary step for many of the Natural Language Processing (NLP) tasks. For this work, various sequential deep learning models such as recurrent neural network (RNN), Long Short-Term Memory (LSTM), Gated Recurrent Unit (GRU) and Bi-directional Long Short-Term Memory (Bi-LSTM) were used at the word level. For evaluating the model, the performance metrics such as precision, recall, F1-score and accuracy were used. Further, a tag set of 32 tags and 225,000 tagged Tamil words was utilized for training. To find the appropriate hidden state, the hidden states were varied as 4, 16, 32 and 64, and the models were trained. The experiments indicated that the increase in hidden state improves the performance of the model. Among all the combinations, Bi-LSTM with 64 hidden states displayed best accuracy (94%). For Tamil POS tagging, this is the initial attempt to be carried out using a deep learning model.
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Authors and Affiliations

S. Anbukkarasi
S. Varadhaganapathy
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Abstract

Squeeze film dampers (SFDs) are commonly used in turbomachinery in order to introduce external damping, thereby reducing rotor vibrations and acoustic emissions. Since SFDs are of similar geometry as hydrodynamic bearings, the REYNOLDS equation of lubrication can be utilised to predict their dynamic behaviour. However, under certain operating conditions, SFDs can experience significant fluid inertia effects, which are neglected in the usual REYNOLDS analysis. An algorithm for the prediction of these effects on the pressure build up inside a finite-length SFD is therefore presented. For this purpose, the REYNOLDS equation is extended with a first-order perturbation in the fluid velocities to account for the local and convective inertia terms of the NAVIER-STOKES equations. Cavitation is taken into account by means of a mass conserving two phase model. The resulting equation is then discretized using the finite volume method and solved with an LU factorization. The developed algorithm is capable of calculating the pressure field, and thereby the damping force, inside an SFD for arbitrary operating points in a time efficient manner. It is therefore suited for integration into transient simulations of turbo machinery without the need for bearing force coefficient maps, which are usually restricted to circular centralized orbits. The capabilities of the method are demonstrated on a transient run-up simulation of a turbocharger rotor with two semi-floating bearings. It can be shown, that the consideration of fluid inertia effects introduces a significant shift of the pressure field inside the SFDs, and therefore the resulting damper force vector, at high oil temperatures and high rotational speeds. The effect of fluid inertia on the kinematic behaviour of the whole system on the other hand is rather limited for the examined rotor.
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Authors and Affiliations

Thomas Drapatow
Oliver Alber
Elmar Woschke
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Abstract

In the domain of affective computing different emotional expressions play an important role. To convey the emotional state of human emotions, facial expressions or visual cues are used as an important and primary cue. The facial expressions convey humans affective state more convincingly than any other cues. With the advancement in the deep learning techniques, the convolutional neural network (CNN) can be used for the automatically extracting the features from the visual cues; however variable sized and biased datasets is a vital challenge to be dealt with as far as implementation of deep models is concerned. Also, the dataset used for training the model plays significant role in the retrieved results. In this paper, we have proposed a Multi-Model Hybrid Ensemble Weighted Adaptive approach with decision level fusion for personalized affect recognition based on the visual cues. We have used a CNN and pre-trained ResNet-50 model for the transfer learning. VGGFace model’s weights are used to initialize weights of ResNet50 for fine-tuning the model. The proposed system shows significant improvement in test accuracy in affective state recognition compared to the singleton CNN model developed from scratch or transfer learned model. The proposed methodology is validated on The Karolinska Directed Emotional Faces (KDEF) dataset with 77.85% accuracy. The obtained results are promising compared existing state of the art methods.
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Authors and Affiliations

Nagesh Narayan Jadhav
Rekha S Sugandhi
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Abstract

The following paper presents wind tunnel investigation of aerodynamic characteristics of hovering propellers. This propulsion system may be applied on a lightweight Quad Plane VTOL (Vertical Take-Off and Landing) UAV (Unmanned Aerial Vehicle). A Quad Plane is a configuration consisting of a quadcopter design combined with a conventional twin-boom airplane. This kind of design should therefore incorporate the advantages of both types of vehicles in terms of agility and long endurance. However, those benefits may come with a cost of worse performance and higher energy consumption. The characteristics of a fixed-wing aircraft and propellers in axial inflow are well documented, less attention is put to non-axial flow cases. VTOL propellers of a hybrid UAV are subject to a multitude of conditions – various inflow speeds and angles, changing RPMs, interference between propellers and between nearby aerodynamic structures. The tested system presented in this article consists of four electric motors with two coaxial pairs of propellers mounted on one of the fuselage beams. Such a configuration is often chosen by designers of small and medium hybrid UAVs. There is a need for studies of clean, efficient ways of transporting, and this article can aid future designers of a new type of electric UAVs.
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Katarzyna Pobikrowska
Tomasz Goetzendorf-Grabowski
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Abstract

The paper presents an analysis of the influence of the shape of the rigid body pressed into the microperiodic composite half-space on the examples of two punch shapes – parabolic and rectangular. The presented material is a layered body that consists of infinitely many thin alternately arranged homogenous layers. Layers of the presented composite are oblique to the boundary surface. Two cases of punch tip shape are examined – parabolic and rectangular. The presented problem has been formulated within the framework of homogenized model with microlocal parameters and solved using elastic potentials method and averaged boundary condition. Fourier integral transform method has been used to obtain the solution and the inverse integrals have been calculated numerically. Solutions in terms of contact pressure and maximum pressure characteristics were shown in the form of figures.
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Authors and Affiliations

Piotr Sebestianiuk
Dariusz M. Perkowski
Roman Kulchytsky-Zhyhailo
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Abstract

This paper presents the design of a versatile mechanism that can enable new directions in amphibious, all-terrain locomotion. The simple, passive, flapped-paddle can be integrated with several structures that are well-suited for locomotion in terrestrial applications. The flapped-paddle overcomes a serious limitation of the conventional flipper where the net lateral forces generated during oscillatory motion in aquatic environments averages out to zero. The flapped-paddle and its mounting, collectively, rests in natural positions in the aquatic environment so as to maximize hydrodynamic force utilization and consequently the propulsive efficiency. The simplicity of the design enabled us to develop a simulation model that concurs well with experimental results. The results reported in the paper are based on integrating the flapped-paddle with the curved leg of the RHex hexapod robot.
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Authors and Affiliations

Piotr Burzynski
Ashutosh Simha
Ülle Kotta
Ewa Pawluszewicz
Shivakumar Sastry
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Abstract

The above-threshold operation of a Fabry-Perot laser with a nonlinear PT (Parity Time) mirror is investigated. For the first time, the analysis accounts for gain saturation of an active medium as well as gain and loss saturation effects in the PT mirror. The obtained laser output intensity characteristics have been demonstrated as a function of various PT mirror parameters such as: ratio of the PT structure period to laser operating wavelength, number of PT mirror primitive cells, and gain and loss saturation intensities of the PT mirror gain and loss layers. Two functional configurations of the laser have been considered: laser operating as a discrete device, and as a component of an integrated circuit. It has been shown that, in general, the laser operation depends on the PT mirror orientation with respect to the active medium of the laser. Moreover, when the laser radiation is outcoupled through the PT mirror to the free space, bistable operation is possible, when losses of the mirror’s loss layer saturate faster than gain of the gain layer. Furthermore, for a given saturation intensity of the mirror loss layers, the increase of the saturation intensity of the mirror gain layers causes increasing output intensity, i.e. the PT mirror additionally amplifies the laser output signal.
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Authors and Affiliations

Agnieszka Mossakowska-Wyszyńska
Piotr Witoński
Paweł Szczepański
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Abstract

This article deals with the effect of selected machining parameter values in hard turning of tested OCHN3MFA steel in terms of SEM microstructural analysis of workpiece material, cutting forces, long-term tests, and SEM observations of flank wear VB and crater wear KT of used changeable coated cemented carbide cutting inserts in the processes of performed experiments. OCHN3MFA steel was selected as an experimental (workpiece) material. The selected experimental steel was analysed prior to hard turning tests, due to checking of the initial microstructure of bulk material and subsurface microstructure after hard turning and chemical composition. Study of the microstructure of workpiece material and also worn cemented carbide cutting inserts was performed with Tescan Vega TS 5135 scanning electron microscope (SEM) with the X-Ray microanalyzer Noran Six/300. Chemical composition of workpiece material was analyzed with Tasman Q4 surface analyzer. All hard turning experiments of the used specimens were performed under the selected machining parameters in the SU 50A machine tool with the 8th selected individual geometry of coated cementite carbide cutting inserts clamped in the appropriate DCLNR 2525M12-M type of cutting tool holder. During the hard turning technological process of individual tested samples made of OCHN3MFA steel, cutting forces were measured with a Kistler 9257B piezoelectric dynamometer, with their subsequent evaluation using Dynoware software. Other experiments and results following the long-term testing were also realized, evaluating the influence of selected machining parameters with different cutting insert geometry on the achieved surface quality.
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Authors and Affiliations

Jozef Majerík
Igor Barényi
Zdenek Pokorný
Josef Sedlák
Vlastimil Neumann
David Dobrocký
Aleš Jaroš
Michal Krbaťa
Jozef Jambor
Robert Kusenda
Miroslav Sagan
Jiri Procházka
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Abstract

The article discusses the applicability of a novel method to determine horizontal curvature of the railway track axis based on results of mobile satellite measurements. The method is based on inclination angle changes of a moving chord in the Cartesian coordinate system. In the presented case, the variant referred to as the method of two virtual chords is applied which consists in manoeuvring with only one GNSS (Global Navigation Satellite System) receiver. The assumptions of the novel method are formulated, and the assessment of its application in the performed campaign of mobile satellite measurements is given. The shape of the measured railway axis is shown in the national spatial reference system PL-2000, and the speed of the measuring trolley during the measurement is calculated based on the recorded coordinates. It has been observed that over the test section, the curvature ordinates differ from the expected waveform, which can be caused by disturbances of the measuring trolley trajectory. However, this problem can easily be overcome by filtering the measured track axis ordinates to obtain the correct shape – this refers to all track segments: straight sections, circular arcs, and transition curves. The virtual chord method can also be the basis for assessing the quality of the recorded satellite signal. The performed analysis has shown high accuracy of the measuring process.
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Authors and Affiliations

Władysław Koc
Andrzej Wilk
Cezary Specht
Krzysztof Karwowski
Jacek Skibicki
Krzysztof Czaplewski
Slawomir Judek
Piotr Chrostowski
Jacek Szmagliński
Paweł Dąbrowski
Mariusz Specht
Sławomir Grulkowski
ORCID: ORCID
Roksana Licow
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Abstract

In the article the results of simulation and experimental studies of the movement of a four-wheeled mobile platform, taking into account wheel slip have been presented. The simulation results have been based on the dynamics of the four-wheel mobile platform. The dynamic model of the system motion takes into account the relationship between the active and passive forces accompanying the platform motion, especially during wheel slip. The formulated initial problem describing the motion of the system has been solved by the Runge-Kutta method of the fourth order. The proposed computational model including the platform dynamics model has been verified in experimental studies using the LEO Rover robot. The motion parameters obtained on the basis of the adopted computational model in the form of trajectories, velocities and accelerations have been compared with the results of experimental tests, and the results of this comparison have been included in the paper. The proposed computational model can be useful in various situations, e.g. real-time control, where models with a high degree of complexity are useless due to the computation time. The simulation results obtained on the basis of the proposed model are sufficiently compatible with the results of experimental tests of motion parameters obtained for the selected type of mobile robot.
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Authors and Affiliations

Anna Jaskot
Bogdan Posiadała
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Abstract

In this paper, the performance and frequency bandwidth of the piezoelectric energy harvester (PZEH) is improved by introducing two permanent magnets, which is attached to the proof mass of a dual beam structure. Both magnets are in the vicinity of each other and attached in such as a way to proof mass of a dual-beam, so that they create a magnetic field around each other. The generated magnetic field develops a repulsive force between the magnets, which improves not only electrical output but also enhances the bandwidth of harvester. The simple rectangular cantilever structure with and without magnetic tip mass has the frequency bandwidth of 4 Hz and 4.5 Hz respectively. The proposed structure generates a peak voltage of 20 V at a frequency of 114.51 Hz at an excitation acceleration of 1g (g = 9.8 m/s2). The peak output power of a proposed structure is 12.2 μW. The operational frequency range of a proposed dual-beam cantilever with magnetic tip mass of 30 mT is from 102.51 Hz to 120.51 Hz i.e., 18 Hz. The operational frequency range of a dual-beam cantilever without magnetic tip mass is from 104.18 Hz to 118.18 Hz i.e., 14 Hz. There is an improvement of 22.22% in the frequency bandwidth of proposed dual-beam cantilever with magnetic tip mass of 30 mT than the dual-beam without magnetic tip mass.
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Authors and Affiliations

Ashutosh Anand
Srikanta Pal
Sudip Kundu
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In the paper the numerical method of solving the one-dimensional subdiffusion equation with the source term is presented. In the approach used, the key role is played by the transformation of the partial differential equation into an equivalent integro-differential equation. As result of the discretization of the integro-differential equation obtained an implicit numerical scheme which is the generalized Crank-Nicolson method. The implicit numerical schemes based on the finite difference method, such as the Carnk-Nicolson method or the Laasonen method, as a rule are unconditionally stable, which is their undoubted advantage. The discretization of the integro-differential equation is performed in two stages. First, the left-sided Riemann-Liouville integrals are approximated in such a way that the integrands are linear functions between successive grid nodes with respect to the time variable. This allows us to find the discrete values of the integral kernel of the left-sided Riemann-Liouville integral and assign them to the appropriate nodes. In the second step, the derivative of the second order with respect to the spatial variable is approximated by the difference quotient. I verify the obtained numerical scheme on three examples for which closed analytical solutions are known.
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Marek Błasik
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Abstract

The blast mitigation in case of military vehicles is still a popular field of research. The main problem is coping with the vehicle global motion consequences after the explosion. The paper presents a possibility of an application of the linear Vacuum Packed Particle (VPP) damper as a supplementation for a viscous shock absorber in a traditional blast mitigation seat design. The paper presents field test results for the underbelly blast explosion and comparing them to the laboratory tests carried out on the impact bench. To collect accelerations, the Anthropomorphic Test Device – Hybrid III dummy was used. The set of numerical simulations of the modified blast mitigation seat with the additional VPP linear damper were revealed. The VPP damper was modeled by the Johnson-Cook model of the viscoplasticity. The Hertzian contact theory was adopted to model the contact between the vehicle and the ground. The reduction of the Dynamic Response Index (DRI) in case of the VPP damper application was proved.
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Authors and Affiliations

Dominik Rodak
Mateusz Żurawski
Michał Gmitrzuk
Lech Starczewski
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Abstract

Unmanned vehicles are often used in everyday life, mostly by rescue teams or scientist during exploration of new terrains. In those constructions suspension has constant dimensions what leads to many disadvantages and more over limits application area. The solution of these problems can be a creation of a six – wheeled mobile platform which can dynamically change wheel base in relation to the area of action or terrain inclination angle. The active change in location of center of gravity gives a possibility to access sloppy obstacles not available with classical suspensions. The main scope of this study is to investigate an influence of material properties on vibration frequency at different length of suspension members. The obtained results will allow finding the optimum material for production of a prototype unit.
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Authors and Affiliations

Krzysztof Sokół
Maciej Pierzgalski
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Abstract

The following discussion concerns the use of innovative smart materials called vacuum-packed particles (VPP) as active energy absorbers. VPP, also known as a granular jamming system, is a structure composed of granular media contained within an elastomer coating. By changing the vacuum pressure inside the coating, it is possible to control the mechanical properties of the structure. VPP have many applications, e.g. in medicine, robotics and vibration damping. No attempts have yet been made to use VPP to absorb the energy of a collision, although given their properties, this could very well be an interesting application. In the first part of the paper, the general concept of the absorber is presented. Then a protype and the empirical tests conducted are precisely described. The middle part of the paper considers the basic properties of VPP and modeling methodology. A proposal for a constitutive equation is presented, and a numerical simulation using LS-Dyna was performed. In the final section, the concept of a smart parking post is presented.
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Authors and Affiliations

Piotr Bartkowski
Hubert Bukowiecki
Franciszek Gawiński
Robert Zalewski
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Abstract

This paper presents the concept of the modelling methodology of a payload-vessel system allowing for a comprehensive investigation of mutual interactions of the system dynamics for lifting in air. The proposed model consists of six degrees of freedom (6-DoF) vessel and three degrees of freedom (3-DoF) lifting model that can replace the industrial practice based on a simplified approach adopted for light lifts. Utilising the response amplitude operators (RAO’s) processing methodology provides the ability to incorporate the excitation functions at the vessel crane tip as a kinematic and analyse a wide spectrum of lifted object weights on a basis of regular wave excitation. The analytical model is presented in details and its solution in a form of numerical simulation results are provided and discussed within the article. The proposed model exposes the disadvantages of the models encountered in engineering practice and literature and proposes a novel approach enabling efficient studies addressing a lack of access to reliable modelling tools in terms of coupled models for offshore lifting operations planning.
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Authors and Affiliations

Anna Mackojć
Bogumil Chiliński
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Abstract

Background: Computer Aided Detection systems are used for the provision of second opinion during lung cancer diagnosis. For early stage detection and treatment false positive reduction stage also plays a vital role. The main motive of this research is to propose a method for lung cancer segmentation. In the recent year’s lung cancer detection and segmentation of tumor is considered one of the most important steps in the surgical planning and medication preparations. It’s very difficult for the researchers to detect the tumor area from the CT (Computed Tomography) images. Method: The proposed system segments lungs and classify the images into normal and abnormal andis consisting of two phases, First phase will be consisting of various stages like Pre-processing, feature extraction, feature selection, classification and finally segmentation of the tumor. Input CT image is sent through the pre-processing phase where noise removal will be taken care and then texture features are extracted from the pre-processed image, and in the next stage features will be selected by making use of Crow Search Optimization Algorithm, later Artificial Neural Network is used for the classification of the normal lung images from abnormal images. Finally, abnormal images will be processed through the Fuzzy K-Means algorithm for segmenting the tumors separately. In the second phase, SVM classifier is used for the reduction of false positives. Result: The proposed system is delivering an accuracy of 96%, 100% specificity and sensitivity of 99% and it reduces false positives. Experimental Results shows that the system outperforms many other systems in the literature in terms of sensitivity, specificity and accuracy. There is a great tradeoff between effectiveness and efficiency and the proposed system also saves computation time. Conclusion: The work shows that the proposed system which is formed by the Integration of Fuzzy K-Means Clustering and Deep Learning technique is simple yet powerful and was effective in reducing false positives and segments tumors and perform classification and also delivers better performance when compared to other strategies in the literature, and this system is giving accurate decision when compared to human doctor’s decision.
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Authors and Affiliations

J Maruthi Nagendra Prasad
S. Chakravarty
M. Vamsi Krishna

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