2022 - Repozytorium publikacji - Politechnika Gdańska

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Using differential pressure sensor to measure nitrous oxide level in a tank
- Mateusz Czapski
- Wiktor Lachowski
- Natalia Balogh
- Wojciech Deszczyński
- Krzysztof Hucik
- Wiktor Sieklicki
2022 Pełny tekst
A method for measuring the level of liquid nitrous oxide oxidizer in a hybrid rocket motor oxidizer tank is proposed. Presented approach is more accurate than the most commonly used method of this measurement, which employs weighting of the whole sounding rocket or an oxidizer tank. In our solution we use a differential pressure sensor to measure the change of pressure at the bottom of an oxidizer tank in comparison to the pressure of the gas phase above the liquid. Due to usage of a relatively short oxidizer tank, with height of 900 mm, and density of nitrous oxide being smaller than water, at 786.6 kg m3 , measured pressure differences are small, which requires high resolution of the sensor. Our system was prepared to work in a hybrid rocket motor of SimLE student organisation from Gdansk University of Technology (Gdansk, Poland). Developed propulsion system is designed to allow a sounding rocket with 4 kg of payload to accurately reach a flight altitude of 3000 m. The reason for accurate calculation of oxidizer amount in a tank is precise altitude planning for a sounding rocket launch which does not employ any active aerobraking system. For this flight strategy, accurate measurement of engine parameters is crucial. The described system is theoretically able to measure liquid level with a 5 mm resolution, which corresponds to roughly 50 g of nitrous oxide in the tank. Other approach, using a load cell, showed measurement resolution of 100 g of weight difference. This method was susceptible to hysteresis due to friction and other external conditions on a launch rail. Preliminary results from hybrid rocket engine tests are presented along with perspective for further method improvement.
Using Disparity Map for Moving Object Position Estimation in Pan Tilt Camera Images
- Tomasz Kocejko
- Jacek Rumiński
- Jo Kang-Hyun
2022
In this paper we present the algorithm for rapid moving object position estimation in an images acquired from pan tilt camera. Detection of a moving object in a image acquired from a moving camera might be quite challenging. Standard methods that relay on analyzing two consecutive frames are not applicable due to the changing background. To overtake this problem we decided to evaluate the possibility of calculating a disparity map based on this consecutive images. As a result we were able to obtain approximate position of moving object in real time. Using cpu the average detection time was below 0.17 second.
Using Long-Short term Memory networks with Genetic Algorithm to predict engine condition
- Semra Erpolat Tasabat
- Olgun Aydin
2022 Gazi University Journal of Science
Predictive maintenance (PdM) is a type of approach for maintenance processes, allowing maintenance actions to be managed depending on the machine's current condition. Maintenance is therefore carried out before failures occur. The approach doesn’t only help avoid abrupt failures but also helps lower maintenance cost and provides possibilities to manufacturers to manage maintenance budgets in a more efficient way. A new deep neural network (DNN) architecture proposed in this study intends to bring a different approach to the predictive maintenance domain. There is an input layer in this architecture, a Long-Short term memory (LSTM) layer, a dropout layer (DO) followed by an LSTM layer, a hidden layer, and an output layer. The number of epochs used in the architecture and the batch size was determined using the Genetic Algorithm (GA). The activation function used after the output layer, DO ratio, and optimization algorithm optimizes loss function determined by using grid search (GS). This approach brings a different perspective to the literature for finding optimum parameters of LSTM. The neural network and hyperparameter optimization approach proposed in this study performs much better than existent studies regarding LSTM network usage for predictive maintenance purposes
Using Minimum Actuators to Control Shape and Stress of a Double Layer Spherical Model Under Gravity and Lateral Loadings
- Najmadeen Saeed
- Javad Katebi
- Ahmed Manguri
- Aram Mahmood
- Marcin Szczepanski
- Robert Jankowski
2022 Pełny tekst Advances in Science and Technology Research Journal
Spherical domes are picturesque structures built in developed countries to attract tourists. Due to horizontal and vertical overloading, the structures’ attractive shapes may be disturbed, and some members' stress may exceed the elastic level. In this paper, the shape and stress of a deformed double-layer spherical numerical model due to simultaneous lateral and vertical loadings are controlled, meanwhile, the number of actuators to alter the length of active members is minimized. The nodal displacements of the outer shape of the numerical model of the double-layer spherical structure are nullified. In addition, the stress of the members of the structure was monitored to stay within the elastic level. Moreover, the number of used actuators was minimized. These objectives are done by subjecting controlling formulations to a function that finds the minimum of constrained nonlinear multivariable which is called fmincon. The defined function in MATLAB uses one of the optimization algorithms (sequential quadratic programming, interior point, trust-region reflective, and active set). The algorithms search for active members that have a significant influence in controlling the targeted joints and members. Furthermore, the algorithms exclude the inactive actuators in several loops. The results obtained from MATLAB program are validated by SAP2000 software.
Using Synchronously Registered Biosignals Dataset for Teaching Basics of Medical Data Analysis – Case Study
- Tomasz Kocejko
2022 Pełny tekst
Medical data analysis and processing strongly relies on the data quality itself. The correct data registration allows many unnecessary steps in data processing to be avoided. Moreover, it takes a certain amount of experience to acquire data that can produce replicable results. Because consistency is crucial in the teaching process, students have access to pre-recorded real data without the necessity of using additional equipment for data acquisition. The analyzed sample dataset consists of raw signals of ECG, Body Impedance and Body temperature recorded synchronously in laboratory conditions. The data are sampled with 250Hz sampling frequency and are framed in blocks. Students gain a chance to acquire, exchange and process the medical data in simulated conditions. Pre-recording data provides the opportunity to teach certain techniques that can be used in real life scenarios but in a control replicable environment.
Validated GC–MS method for determination of bisphenol a and its five analogues in dietary and nutritional supplements
- Katarzyna Owczarek
- Emilia Waraksa
- Ewa Kłodzińska
- Yaroslav Zrobok
- Mariusz Ozimek
- Dominik Rachoń
- Błażej Kudłak
- Andrzej Wasik
- Zofia Mazerska
2022 MICROCHEMICAL JOURNAL
Bisphenol A (BPA) and its analogues showing structural and functional similarity to BPA are commonly applied in various industrial applications and thus are becoming ubiquitous in the environment. At the same time there is increasing scientific evidence that exposure to these chemicals may lead to adverse health effects in human and wildlife. In recent years dietary and nutritional supplements dedicated for athletes have become more popular and are widely used even by people who are not professionals. This study presents the development, optimization and validation of an analytical procedure for determination of six bisphenol analogues in dietary supplements using gas chromatography – mass spectrometry technique. All validation parameters met the established acceptance criteria in accordance with international guidelines.
Validating the Rules of Government Automation
- Elsa Estevez
- Tomasz Janowski
- David Benjamin Roseth
2022
There is growing evidence on the benefits and risks of government automation, and how should government organizations proceed with automation when the benefits outweigh the risks. This evidence was recently consolidated into the "rules of government automation", part of the project funded by the Inter-American Development Bank. The project uncovered that the combined nature of government work and its transformation into digital government create many opportunities for automation. However, such opportunities can be only realized when the right automation technology becomes available and when government organizations are willing, capable, and authorized to introduce it, considering the impact on the organization and its stakeholders and the balance of benefits and risks brought about by this impact. The aim of the workshop is to validate the above “rules of government automation”. To this end, the participants will bring to the workshop their own government automation cases, from practice or research, establish thorough inspection and guided reasoning whether the rules hold for their cases, refine them otherwise, and iteratively agree on the refined rules across all cases. The workshop will also initiate the planning of a special issue of Government Information Quarterly to advance the theory and practice of government automation.
VALUATION OF EMBEDDED OPTIONS IN NON-MARKETABLE CALLABLE BONDS: A NEW NUMERICAL APPROACH
- Roman Skalický
- Marek Zinecker
- Adam P. Balcerzak
- Michał Pietrzak
- Elżbieta Rogalska
2022 Pełny tekst Technological and Economic Development of Economy
The issue of how to price options embedded in callable bonds has attracted a lot of interest over the years. The usual bond valuation methods rely on yield curves, risk premium, and other parameters to estimate interest rates used in discounted cash flow calculations. The option to retire the bond is, however, neglected in the standard pricing models, causing a systematic overvaluation of callable bonds. In the event of a decline in interest rates, investors are exposed to the risk of a lower return on investment than indicated by the yield to maturity. We propose a novel approach to valuing the risk that the issuer will use the right to buy back the bond at a specific call price. While prior models are focused on valuing marketable callable bonds, we deliver a unique approach to valuing bonds with an embedded European option (or a multiple option) that are traded solely through private transactions. These can typically be characterized by the lack of historical records on transaction prices. The modular character of calculation we propose allows us to take into account additional information, such as probable behaviour of the issuer, available opportunities for achieving alternative earnings or different estimates in terms of interest rate development.
Variations in host surfaces morphology and biology of ciliate epibionts explaining distribution pattern of epibionts in the invasive signal crayfish Pacifastacus leniusculus (Dana, 1852)
- A. Dobrzycka‐Krahel
- L. Rolbiecki
- Jakub Karczewski
- Marcin Skóra
2022 JOURNAL OF ZOOLOGY
ciliates on the signal crayfish Pacifastacus leniusculus in relation to specialized structures of the host’s exoskeleton for the first time. This species is known to maintain a relatively clean carapace, but it is sometimes overgrown by other organisms. Epibionts cover different parts of the signal crayfish body, mainly antennae, antennules, maxillipedes III and pereiopods with inner edges of chelae; however, some parts of the signal crayfish are not fouled. e.g. dorsal surfaces of the carapace and dorsal surfaces of chelae. Using scanning electron microscopy (SEM), topographies of different parts of the crayfish’s exoskeleton were examined. Our investigations revealed that the epibiosis in the signal crayfish was determined by morphology of body surfaces. No epibionts were found on smooth surfaces with regular single setae (a known design that prevents fouling in aquatic environments). The dimpled surfaces with regular single micro-papillae may be considered as a newly described example of self-cleaning surfaces. Bio-inspired surface patterning presents promising approaches to the design of novel functional surfaces that can prevent biofouling. The new self-cleaning design may be used in further technological applications.
Vehicle Detection and Speed Estimation Using Millimetre Wave Radar
- Piotr Odya
2022 Pełny tekst
The dataset titled Data from 76- to 81-GHz mmWave Sensor located at S7 road contains data recorded employing an IWR1642 mmWave sensor from Texas Instruments. The data comes from two sessions lasting 24h each. The dataset provides the possibility to perform analyses related to car traffic intensity on one of the carriageways of the motorway heading to the Gdańsk metropolitan area. Based on the gathered data, it is possible to calculate the number of vehicles in particular time intervals and to estimate their speed.
Verification and Benchmarking in MPA Coprocessor Design Process
- Tomasz Stefański
- Kamil Rudnicki
- Wojciech Żebrowski
2022
This paper presents verification and benchmarking required for the development of a coprocessor digital circuit for integer multiple-precision arithmetic (MPA). Its code is developed, with the use of very high speed integrated circuit hardware description language (VHDL), as an intellectual property core. Therefore, it can be used by a final user within their own computing system based on field-programmable gate arrays (FPGAs). The coprocessor is still under development and its open-source code is available on the Internet, based on the Mozilla Public License. Therefore, verification and benchmarking of the coprocessor code are vitally important issues as the sources are continually downloaded by users all over the world. In this contribution, we present software tools developed as a part of the system, allowing for detection of errors in the coprocessor code as well as for execution of its benchmarking tests. The research conclusion is that, without well-designed verification and benchmarking software tools, the development of any advanced digital circuit, such as a coprocessor, is actually impossible in realistic time. It stems from the fact that 60% of the project repository include hardware-description codes, whereas the rest of the codes support correct development of the project, i.e., verification and benchmarking in the design process.
Verification of punching shear outside the shear cap by the direct method
- Maciej Grabski
- Andrzej Ambroziak
2022 Pełny tekst Archives of Civil Engineering
The proposition of a method to verify the punching resistance for very large supports based on the EN 1992-1-1 standard is described in this paper. The present standard guidelines for the calculation of the punching resistance for large supports are also summarised. The proposed direct method is compared with other standard methods using an example taken from design practice. This method consists of a direct check of the shear forces at specific locations of the control perimeter with the permissible shear force calculated from the EC2 standard. The method showed very good agreement with the experiment while remaining practical for applications. The method presented takes into account the actual distribution of shear forces in the vicinity of the support, taking into account the influence of non-uniform loads, irregular floor geometry, the concentration of internal forces at the corners of the support and the influence of the stiffness of the head used. The paper provides scientists, engineers, and designers new method (called the direct method) for estimation of the punching load-bearing capacity outside the shear cap.
Verification of Satellite Railway Track Position Measurements Making Use of Standard Co-Ordinate Determination Techniques
- Jacek Szmagliński
- Andrzej Wilk
- Władysław Koc
- Krzysztof Karwowski
- Piotr Chrostowski
- Jacek Skibicki
- Sławomir Grulkowski
- Sławomir Judek
- Roksana Licow
- Karolina Makowska-Jarosik
- Michał Michna
- Tadeusz Widerski
2022 Pełny tekst Remote Sensing
The article presents the results of satellite railway track position measurements performed by a multidisciplinary research team, the members of which represented Gdansk University of Technology and Gdynia Maritime University. Measuring methods are described which were used for reconstructing the railway track axis position and diagnosing railway track geometry deformations. As well as that, the description of the novel method developed by the authors to perform mobile GNSS measurements is included. The reported research aimed at assessing the uncertainty of railway track axis reconstruction making use of the dynamic GNSS method. To assess the applicability of this method, the obtained results were compared with those from the stationary measurement method used in railway business. The data used for comparison was recorded on the same railway track section during several measurement campaigns. In these campaigns, different types of GNSSs with different position recording frequencies (1–100 Hz) were used at different measurement speeds (5–70 km/h). The performed analysis has shown that the accuracy of railway track axis reconstruction making use of mobile GNSS measurements is sufficient for using this methodology in railway business.
Verification of the method of reconstructing convective velocity fields on the basis of temperature fields in vertical, differential and equally heated, open and closed channels
- Krzysztof Tesch
- Michał Ryms
- Witold Lewandowski
2022 Pełny tekst INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
This paper describes a method of reconstructing velocity fields, i.e. a numerical reconstruction procedure (NRP) that involves the numerical processing of experimentally measured temperature distributions in free convection heat transfer. The NRP consists in solving only the continuity and Navier–Stokes equations with an additional source term. This term is proportional to a known temperature (e.g. from a thermal imaging camera) and replaces the Fourier–Kirchhoff equation, which also means that the NRP does not require boundary conditions associated with the temperature to be formulated. In order to verify the NRP, the experimental results of two published cases were taken into consideration. In the first case, the temperature and velocity distributions were determined during free convection heat transfer in a closed cavity, i.e. in a vertical channel formed between differentially heated plates. Subsequently, the velocity distributions obtained by the NRP were compared directly with the experimental results. However, in order to verify the correctness of this method for the entire field, not just for the individual locations, free convection heat transfer measurements in an open channel formed between two isothermal, equally heated plates were considered. A thermal imaging camera was used to detect the temperature field in air. In this case, verification of the NRP method required the results obtained in the form of a reconstructed velocity field to be compared with a field obtained using standard numerical calculations (SNC). Importantly, the NRP provides new opportunities for thermal imaging cameras equipped with a mesh for air temperature detection, for example, the visualisation of air velocity fields in free convective heat transfer.
Vernacular and low-tech technologies in humanitarian architecture on the example of Senegal
- Robert Idem
- Katarzyna Zielonko-Jung
- Aleksandra Karpińska
2022 Pełny tekst Architectus
Humanitarian architecture belongs to the broader trend of socially engaged architecture, whose main goal is to introduce new values to the quality of life of particular communities. Specifically, humanitarian architecture deals with aid to poverty-stricken communities. The context of economic constraints poses a particular challenge to architects and builders. It is a matter of natural necessity to look for cheap, locally available materials and solutions that can be applied by unskilled labor. The above article discusses the applicability of native and low-tech technologies as basic con- struction methods for humanitarian architecture. The research focuses on Senegal, located in West Africa. The article aims to identify material and construction solutions in buildings related to humanitarian aid and social support on behalf of the local community, erected or designed in Senegal. An analysis of four examples in Senegal was conducted, namely, two implemented facilities and two planned ones. The basic criteria for the analysis were provided by the social purpose these objects serve, as well as by the materials and technologies applied. The conclusions concern the types and scope of vernacular and low-tech technologies applied, as well as the correlation between the analyzed objects’ design and construction and sustainable development
VI Sympozjum Historii Elektryki
- Agnieszka Leszczewicz
2022 Pełny tekst Pismo PG
Sympozjum Historii Elektryki jest cykliczną konferencją organizowaną z inicjatywy Centralnej Komisji Historycznej Stowarzyszenia Elektryków Polskich, której celem jest upowszechnianie dorobku i historii oraz podkreślenie roli zasłużonych postaci dla rozwoju elektryki w Polsce. Pracownicy Politechniki Gdańskiej biorą udział w sympozjach od pierwszej edycji. VI Sympozjum Historii Elektryki w 2022 odbyło się w Katowicach i było głównym punktem jubileuszowych X Katowickich Dni Elektryki.
Vibration-Based Investigation of a Historic Bell Tower to Understand the Occurrence of Damage
- Agnieszka Tomaszewska
- Milena Drozdowska
- Czesław Szymczak
2022 International Journal of Architectural Heritage
ABSTRACT The paper presents a survey of the historic Arch-cathedral bell tower in Vilnius induced by the appearance of cracks in the structure after a new bell system installation. An attempt is undertaken to identify the reason for the crack occurrence and to check a possible crack influence on global structural behaviour. The research is based on dynamic measurements made in the tower during ambient vibrations and during vibrations caused by swinging bells. The amplitudes of the accelerations and the spectral peaks due to the ambient and excited vibrations are compared. Magnification of the first spectral peak due to bells swinging points at resonance. The root-meansquare analysis is conducted to detect the tower section most vulnerable to swinging bells. The modal curvature approach applied to the first mode shape serves as the damage indicator. The algorithm locates damage in the region of the cracks observed in the tower; thus, the cracks are considered structural. The research proves the necessity of a dynamic survey in similar cases before important decisions are undertaken regarding the replacement of the bell system.
Video of LEGO Bricks on Conveyor Belt Dataset Series
- Tomasz Boiński
2022 Pełny tekst
The dataset series titled Video of LEGO bricks on conveyor belt is composed of 14 datasets containing video recordings of a moving white conveyor belt. The recordings were created using a smartphone camera in Full HD resolution. The dataset allows for the preparation of data for neural network training, and building of a LEGO sorting machine that can help builders to organise their collections.
Virtual immersive environments
- Jacek Lebiedź
2022
Yet a higher level of active systems may be achieved when users are fully immersed in an interface which is a 3D computer generated virtual world and can interact with surrounding objects of that world as they were in a real one. This is the issue covered by Chapter 7. Interaction in such a world is both multidimensional and multimodal, with the possibility of free movement of the user in any direction and the simultaneous stimulation of several of his/her senses, most often sight, hearing, touch and sense of balance. Moreover, all the techniques discussed previously in Chapters 4-6 may be integrated in the virtual worlds to do both, inducing a specific behavior of the immersed user and providing feedback from the user to the 3D scene generation system. Numerous examples of such applications are presented and discussed in the chapter (from the Preface by Bogdan Wiszniewski, p. iii)
Vision Zero in Poland
- Kazimierz Jamroz
- Aleksandra Romanowska
- Lech Michalski
- Joanna Żukowska
2022 Pełny tekst
Poland’s experience of road safety work is relatively short. In the early 1990s road deaths soared to a staggering 8000 a year. A diagnosis found that Poland’s lack of systemic road safety action was to blame for those figures. In response, the state set up road safety bodies and commissioned road safety programs. In 2005, Poland followed the example of Sweden and adopted Vision Zero as a far-reaching concept of changes in road safety. The work that followed helped to improve the situation and reach less than 3000 fatalities in 2015. Despite that, for years Poland has been notorious for its road accident deaths, which are some of the highest in the EU. Poland has had its share of both successes and failures. The results of road safety policies are still below the expectations and many problems have not been solved. Road accidents are not considered a major problem. As a consequence, they are low on political agendas and the institutions remain ineffective due to a sense of collective responsibility for road safety problems. Achieving Vision Zero will require many changes, learning from past mistakes, taking advantage of the experience of the best performing countries, and, above all, taking effective and efficient actions with their systematic monitoring. This chapter is a summary of the last 30 years of road safety work in Poland. It presents a diagnosis of Poland’s problems, an assessment of the policies so far, and the likelihood of achieving the assumptions of Vision Zero in the future. Building on this, recommendations are given on the next steps Poland should take to improve its road safety.