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Publications from the year 2018
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FEM ANALYSIS AND EXPERIMENTAL TESTS OF RIGID RISER HANGING SYSTEM
- Artur Olszewski
- Michał Wodtke
- Artur Wójcikowski
The article presents the analysis, project, and experimental examination of an original rigid riser for Coil Tubing Pipes. The principle of riser operation is based on the use of friction forces. The research included the FEM analysis of the designed riser, calculations of the required bolt tensions, and checking the effect of the clamping force on stress distribution in the pipeline. The results of computer simulation were verified on a specially designed test rig. The described riser design was implemented on the LOTOS Petrobaltic platform, thus eliminating the need for purchase and installation of expensive elastic risers.
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FEM approach to modeling of an irregular trabecular structure
- Wiktoria Wojnicz
- Edmund Wittbrodt
The aim of the study is elaboration of a method for creating irregular scaffolds that can be used to model the behaviour of trabecular bone placed in the proximal epiphysis of the femur. The scope of the study encompasses creating six numerical models of irregular scaffolds (two solid irregular scaffolds, two shell irregular scaffolds and two shell irregular scaffolds with fortification) and performing numerical analysis of the proposed numerical models applying a finite element method.
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FEM Calculations in Analysis of Steel Subsea Water Injection Flowlines Designing Process
- Michał Wodtke
- Artur Olszewski
- Artur Wójcikowski
Paper describes the result of theoretical research aimed at assessing the loads and operating conditions of a Coiled Tubing pipeline injecting water, suspended to the mining platform of Lotos Petrobaltic. For this purpose, appropriate calculation models have been developed using the Finite Element Method (FEM), taking into account the nature of the analyzed object and its loads. The analyzes were carried out for two pipes (previously operated and newly proposed) differing in geometrical and strength parameters. The research was carried out for selected directions of load on the pipeline (originating from sea waves) and various variants of attaching the suspended pipeline to the mining platform.
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FEM simulation of laminate failure in the three point bending
- Agnieszka Sabik
The paper presents a FEM simulation of failure of laminate subjected to the three point bending. The numeri-cal model is based on the equivalent single layer approach with 6-paramater non-linear shell theory kinematics. It is implemented in the non-commercial FEM code. The failure initiation is detected with the use of Tsai-Wu criterion. After the failure onset the progressive failure process is modelled through the appropriate stiffness parameters reduction. The equilibrium path is traced by means of displacement control. The study shows that the proposed model can serve as effective tool in the failure analysis of laminated structures.
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FEX a Fingers Extending eXoskeleton for Rehabilitation and Regaining Mobility
- Patrizio Sale
- Giovanni Sellin
- Mansiero Stefano
- Francesco Becchi
- Wiktor Sieklicki
This paper presents the design process of an exoskeleton for executing human fingers’ extension movement for the rehabilitation procedures and as an active orthosis purposes. The Fingers Extending eXoskeleton (FEX) is a serial, under-actuated mechanism capable of executing fingers’ extension. The proposed solution is easily adaptable to any finger length or position of the joints. FEX is based on the state-of-art FingerSpine serial system. Straightening force is transmitted from a DC motor to the exoskeleton structures with use of pulled tendons. In trial tests the device showed good usability and functionality. The final prototype is a result of almost half a year of the development process described in this paper.
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FFT analysis of temperature modulated semiconductor gas sensor response for the prediction of ammonia concentration under humidity interference
- Łukasz Woźniak
- Paweł Kalinowski
- Grzegorz Jasiński
- Piotr Jasiński
The increasing environmental contamination forces the need to design reliable devices for detecting of the volatile compounds present in the air. For this purpose semiconductor gas sensors, which have been widely used for years, are often utilized. Although they have many advantages such as low price and quite long life time, they still lack of long term stability and selectivity. Namely, environmental conditions have significant effect on the sensing accuracy. That is caused by the fact that sensors also respond to interfering molecules coexisting in ambient gas (e.g. humidity) and their response is highly dependent on the temperature and the gas delivery rate. Among the different strategies used to overcome those shortcomings, the modulation of the sensors' operating temperature has been reported. To perform the interpretation and extraction of useful information from dynamic nonlinear response of temperature modulated sensor, the feature extraction and data processing methods are required. In this article the method of determination the concentration of ammonia in the presence of relative humidity is presented. For this purpose the operating temperature of a single commercial SnO2 gas sensor is modulated using sinusoidal voltage applied to the heater. The measurements are performed for different concentrations of ammonia at specified levels of relative humidity. The validation data set was obtained 100 days after the set used for the calibration data. Several features from the dynamic measurements are extracted. Qualitative and quantitative analysis of the selection of the signal features containing useful and relevant information for prediction of target gas are performed. The assessment of the impact of the input vector length of the Fast Fourier Transform method on the resulting signal features is examined. The selected features are utilized as an input for Partial Least Squared regression. The calibration is performed and the prediction error of the ammonia concentration is calculated based on the validation data.
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Fiber optic microsphere with a ZnO thin film for potential application in a refractive index sensor – theoretical study
- Marzena Hirsch
Optical fiber sensors of refractive index play an important role in analysis of biological and chemical samples. This work presents a theoretical investigation of spectral response of a fiber optic microsphere with a zinc oxide (ZnO) thin film deposited on the surface and evaluates the prospect of using such a structure for refractive index sensing. A microsphere is fabricated by an optical fiber tapering method on the base of a single mode fiber. The numerical model is described and simulation was conducted to assess the influence of ZnO layer deposition on a reflected signal. The results indicate that a ZnO film improves the performance in terms of application in a refractive index sensor.
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Filozofia sieci 5G - radioinformatyka i wirtualizacja. Część 1. Radioinformatyczny system 5G
- Sławomir Gajewski
- Małgorzata Gajewska
W referacie przedstawiono najważniejsze właściwości sieci 5G, z punktu widzenia jej istoty działania. Uporządkowano najistotniejsze pojęcia służące do opisu sieci 5G, zwłaszcza w kontekście rozwiązań softwarowych, wirtualizacji sieci oraz jej architektury fizycznej i funkcjonalnej. Wprowadzono i zdefiniowano szereg pojęć wynikających z nowej ery rozwoju radiokomunikacji, w tym pojęcie radioinformatyki, systemu radioinformatycznego, sieci radioinformatycznej. Uporządkowano i zdefiniowano główne elementy architektury sieci 5G zgodnie z przebiegiem standaryzacji oraz wskazano sposób integracji sieci 5G z 4G. Pierwsza część artykułu pt. „Radioinformatyczny system 5G” dotyczy w szczególności nowej nomenklatury koniecznej do przyjęcia w radiokomunikacji. Natomiast część druga pt. „Wirtualny system 5G” będzie dotyczyła problemu wirtualizacji w sieci 5G.
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Finite element method simulations of various cases of crash tests with N2/W4/A steel road barrier
- Stanisław Burzyński
- Jacek Chróścielewski
- Łukasz Pachocki
The subject of this study is performance of N2/W4/A steel road safety barrier investigated in numerical simulations. System was checked under several types of initial conditions, which were assumed basing on the TB11 and TB32 normative crash tests. The main goal of present study is to investigate the relationship between initial conditions (angle and velocity) of the impact and the severity indices (associated to the vehicle occupant) during the collision. Obtained performance parameters and impact severity indexes may be considered reasonable. Results of the simulations facilitates the deep insight into vehicle crash mechanics phenomena.
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Finite element simulation of cross shaped window panel supports
- Andrzej Ambroziak
The aim of the work is to verify suitability of cross-shaped window panel supports for mullion-transom wall systems. The Finite Element Method (FEM) is chosen to determine the behaviour of stainless steel elements under loading. The advanced non-linear numerical simulations are carried out using an implicit FEM software package MSC.Marc. This study is proposed to initiate the comprehensive investigation of mechanical properties of cross-shaped window panel supports.
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Finite element/mode-matching analysis of ferrite/dielectric line junctions of arbitrary cross-section
- Adam Kusiek
This paper is focused on the analysis of line junctions obtained as a cascade of dielectric and ferrite guides of arbitrary cross-section. The main application of such structures is nonreciprocal devices such as isolators, circulators, or phase shifters. The efficient finite element/mode-matching approach is proposed to the analysis of such structures. In this approach, thefiniteelementmethod is applied todetermine propagation coefficients and fielddistributions in cross-sections of the structure. Then using mode-matching technique the scattering parameters of investigated junction are calculated. Since, all the field integrals required inmode-matching are evaluated in the pre-processing stage of finite element method, only small numerical effort is required to calculate scattering parameters of the junction. The numerical efficiency of proposed approach is examined for different geometries of longitudinally magnetized shielded ferrite coupled line junction. Obtained results are compared with the ones calculated using commercial software and presented in literature. A very good agreement is achieved
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Firmy komunalne
- Ziemowit Suligowski
Nowe rozwiązania, technologie i możliwości funkcjonowania firm komunalnych. Istniejące zagrożenia. Rozwój technologii bezwykopowych szczególnie w aspekcie budowy rurociągów grawitacyjnych.
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Fixed point indices of iterates of a low-dimensional diffeomorphism at a fixed point which is an isolated invariant set
- Grzegorz Graff
Let f be an R^n-diffeomorphism, where n = 2, 3, for which {0} is an isolated invariant set. We determine all possible forms of the sequences of fixed point indices of iterates of f at 0, {ind(f n, 0)}_n, confirming in R3 the conjecture of Ruiz del Portal and Salazar (J Differ Equ 249, 989–1013, 2010).
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Flame retardant epoxy/halloysite nanotubes nanocomposite coatings: Exploring low-concentration threshold for flammability compared to expandable graphite as superior fire retardant
- Henri Vahabi
- Mohammad Saeb
- Krzysztof Formela
- José-Marie Cuesta
Epoxy nanocomposites containing halloysite nanotubes (HNTs) were developed and their low-concentration thresholds for thermal stability and flame retardancy were compared with that of epoxy system containing expandable graphite (EG), as a reference with superior flame retardancy. The effects of HNTs and EG on the peak of Heat Release Rate (pHRR), Total Heat Release (THR), and Time-To-Ignition (TTI) of the prepared samples were subsequently discussed. At low loading level of 3 wt.%, HNTs appeared more effective, as signaled by an enhanced thermal stability compared to the EG-incorporated composite at an identical loading, because of hindered mobility of epoxy chains in a well-cured epoxy network. At higher loadings (6 and 9 wt.%), however, exfoliation of EG because of heat build-up in the system was dominantly hindered the crosslinking of epoxy it the presence of HNTs, which consequently deteriorated thermal stability of epoxy. This was featured by the formation of intumescent flake on the surface of the epoxy that played the role of a physical barrier, and assisted in reduction of the value of pHRR, while it doubled the TTI value. Different functions of HNTs and EG in regard with thermal stability and flame retardancy of epoxy/amine systems were discussed experimentally and mechanistically.
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Flexible Knowledge–Vision–Integration Platform for Personal Protective Equipment Detection and Classification Using Hierarchical Convolutional Neural Networks and Active Leaning
- Edward Szczerbicki
- Caterine Silva de Oliveira
- Cesar Sanin
This work is part of an effort to develop of a Knowledge-Vision Integration Platform for Hazard Control (KVIP-HC) in industrial workplaces, adaptable to a wide range of industrial environments. The paper focuses on hazards resulted from the non-use of personal protective equipment (PPE). The objective is to test the capability of the platform to adapt to different industrial environments by simulating the process of randomly selecting experiences from a new scenario, querying the user, and using their feedback to re-train the system through a hierarchical recognition structure using Convolutional Neural Network (CNN). Thereafter, in contrast to the random sampling, the concept of active learning based on pruning of redundant points is tested. Results obtained from both random sampling and active learning are compared with a rigid systems that is not capable to aggregate new experiences as it runs. From the results obtained, it can be concluded that the classification accuracy improves greatly by adding new experiences, which makes it possible to customize the service according to each scenario and application as it functions. In addition, the active learning approach was able to reduce the user query and slightly improve the overall classification performance, when compared with random sampling.
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Forecasted climate changes and their influence on cities and regions in 2050 in terms of extreme hydrological events
- Julia Kurek
- Justyna Martyniuk-Pęczek
Global climate change is a problem which arises numerous theories and uncertainties, especially in terms of speculated human impact. Independent from the fact, what is the main driver for the changes, some of the climate shifts are visible already nowadays. Both contemporary and future cities will have to face such problems. Although climate change may cause numerous effects on different fields, a special stress in this article is laid on hydrological events – which are possible to observe even in these days. The purpose of this article is to indicate the main approaches both to the issue of climate change and activities undertaken by cities in relation to hydrological threats.
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Forecasting of railway track tamping based on settlement of sleepers using fuzzy logic
- Eligiusz Mieloszyk
- Sławomir Grulkowski
- Anita Milewska
The sleepers in a railway track transfer vertical, transverse and longitudinal loads to the track ballast and subgrade. The sleepers allow for keeping the distance between the rails constant. The thickness of ballast should be between 16 and 35 cm depending on the design standard of the track, and it should be densified where the ballast supports the sleeper. The exploitation causes contamination of the ballast, crushing the material under cyclic dynamic loads, which results in the settlement of sleepers. Consequently, the thickness of ballast is not sufficient and the effects such as longitudinal unevenness of rails and track twist appear. Those effects have negative impact on the comfort and travel safety, in the extreme cases leading to the derailment. The parameters like ballast thickness, degree of its contamination, its density and sleepers’ settlement are difficult to measure so that they can be considered as ‘fuzzy’. Therefore, the fuzzy sets and transfer functions are used to determine those parameters. The cause and effect relationships and their impact on the reliability of the system will be analyzed in the fuzzy sets’ domain. Special attention will be paid to use this concept in forecasting the track tamping to enhance the interaction of the track surface with the soil ground and to increase safety.