2019 - Repozytorium publikacji - Politechnika Gdańska

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Recent Achievements in Constitutive Equations of Laminates and Functionally Graded Structures Formulated in the Resultant Nonlinear Shell Theory
- Stanisław Burzyński
- Jacek Chróścielewski
- Karol Daszkiewicz
- Agnieszka Sabik
- Bartosz Sobczyk
- Wojciech Witkowski
2019
The development of constitutive equations formulated in the resultant nonlinear shell theory is presented. The specific features of the present shell theory are drilling rotation naturally included in the formulation and asymmetric measures of strains and stress resultants. The special attention in the chapter is given to recent achievements: progressive failure analysis of laminated shells and elastoplastic constitutive relation for shells made of functionally graded material (FGM). The modified Hashin criterion is used to estimate failure initiation in laminates and stiffness degradation approach in the last ply failure computations. The numerical results obtained for axially compressed C-shaped column are compared with experimental load-deflection curve. The Cosserat plane stress assumption, Tamura-Tomota-Ozawa (TTO)model and improvedmethod of shear correction factor calculation are applied in the elastoplastic constitutive relation for FGM shell. The proposed formulation is tested in numerical examples: rectangular compressed plate and channel section clamped beam. The influence of TTO model parameters and Cosserat characteristic length is investigated.
Recent trends in determination of neurotoxins in aquatic environmental samples
- Małgorzata Rutkowska
- Justyna Płotka-Wasylka
- Tomasz Majchrzak
- Wojciech Wojnowski
- Hanna Mazur-Marzec
- Jacek Namieśnik
2019 TRAC-TRENDS IN ANALYTICAL CHEMISTRY
Anatoxins, saxitoxins, ciguatoxins, beta-N-methylamino-l-alanine and its isomers are groups of neurotoxins which have a highly specific effect on the nervous system of animals, including humans, by interfering with the transmission of nerve impulses. In order to assess the human exposure to these neurotoxins, selective, interlaboratory-validated analytical methods are being developed to facilitate obtaining reliable results on the levels of neurotoxins both in the water and in biological samples. The aim of this work is to provide an overview of the state of the art of analytical techniques used for isolation and determination of neurotoxins from samples of aquatic ecosystems. This work also constitutes an attempt to outline the current state of knowledge in regard to the occurrence of neurotoxic compounds in aquatic ecosystems on the basis of studies in which adequate analytical methods were used.
Reclaimed rubber in-situ grafted with soybean oil as a novel green reactive plasticizer in SBR/silica compounds
- Adeel Hassan
- Krzysztof Formela
- Shifeng Wang
2019 ACS Sustainable Chemistry & Engineering
Polymer recycling and biodegradable polymeric materials are two major routes towards the sustainable development of polymer materials which contributes to the management of waste. In this regard, an eco-friendly approach is presented wherein high reclaiming degree of ground tire rubber (GTR) was achieved by low-temperature oxidation under swollen action of soybean oil. In-situ reclaimed GTR with soybean oil was cured into reactive plasticizer (RP) through a free-radical chain reaction between activated molecular rubber chains and soybean oil. During the curing process, degraded rubber chains were involved in synergistic reactions of recombination to strengthen bound rubber involved with core-shell structure carbon black and grafting with soybean oil. RP was obtained by modification of highly reclaimed rubber to control leachable oils and to modulate the reaction. Reactive plasticizers are further explored as a multifunctional additive to styrene-butadiene rubber/silica compounds. Reactive plasticizers performed the following three functions towards styrene-butadiene rubber/silica compounds: i) value-added rubber substitute; ii) reinforcing filler with the increase in tensile strength maximum up to 112% approximately on account of bound rubber involved with core-shell structure carbon black; and most importantly, as a iii) reactive plasticizer.
Recovering Sound Produced by Wind Turbine Structures Employing Video Motion Magnification
- Sebastian Cygert
- Andrzej Czyżewski
- Marta Stefaniak
- Bożena Kostek
2019
The recordings were made with a fast video camera and with a microphone. Using fast cameras allowed for observation of the micro vibrations of the object structure. Motion-magnified video recordings of wind turbines on a wind farm were made for the purpose of building a damage prediction system. An idea was to use video to recover sound & vibrations in order to obtain a contactless diagnostic method for wind turbines. The recovered signals can be analyzed in a way similar to accelerometer signals, employing spectral analysis. They can be also played back through headphones and compared with sounds recorded by microphones.
Recurrence scheme for FDTD-compatible discrete Green's function derived based on properties of Gauss hypergeometric function
- Jacek Gulgowski
- Tomasz Stefański
2019 JOURNAL OF ELECTROMAGNETIC WAVES AND APPLICATIONS
In this paper, the formulation of one-dimensional FDTD (Finite-difference time-domain)-compatible discrete Green's function (DGF) is derived based on the Gauss hypergeometric function (GHF). The properties of GHF make it possible to derive the recurrence scheme only in the time domain for the DGF generation. Furthermore, this recurrence scheme is valid for any stable time-step size and can be implemented using standard numerical precision of computations. The proposed derivation is obtained without processing in any symbolic mathematics software and relies on the application of known properties of GHF. The difference between the developed recurrence scheme and the direct FDTD simulation is approximately at the level of numerical noise, which confirms the correctness of our derivation. The results obtained should be useful for the development of computational techniques employing FDTD and the diakoptic approach.
Recykling metali z zużytych modułów fotowoltaicznych
- Anna Kuczyńska-Łażewska
- Ewa Klugmann-Radziemska
2019 Przemysł Chemiczny
Zaprezentowano stan wiedzy na temat dotychczas opracowanych metod odzysku metali z roztworów. Przeanalizowano je pod kątem wykorzystania w procesach recyklingu modu- łów wykonanych z krystalicznego krzemu oraz w technologii cienkowarstwowej.
Reduced-cost design closure of antennas by means of gradient search with restricted sensitivity update
- Sławomir Kozieł
- Anna Pietrenko-Dąbrowska
2019 Pełny tekst Metrology and Measurement Systems
Design closure, i.e., adjustment of geometry parameters to boost the performance, is a challenging stage of antenna design process. Given complexity of contemporary structures, reliable parameter tuning requires numerical optimization and can be executed using local algorithms. Yet, EM-driven optimization is a computationally expensive endeavour and reducing its cost is highly desirable. In this paper, a modification of the trust-region gradient search algorithm is proposed for accelerated optimization of antenna structures. The algorithm is based on sparse updates of antenna sensitivities involving various methods that include the Broyden formula used for selected parameters, as well as dimensionality- and convergence-dependent acceptance thresholds which enable additional speedup, and make the procedure easy to tune for various numbers of antenna parameters. Comprehensive verification executed for a set of benchmark antennas delivers consistent results and considerable cost reduction of up to 60 percent with respect to the reference algorithm. Experimental validation is also provided.
Reduced-Cost Design Optimization of High-Frequency Structures Using Adaptive Jacobian Updates
- Sławomir Kozieł
- Anna Pietrenko-Dąbrowska
- Leifur Leifsson
2019 Pełny tekst
Electromagnetic (EM) analysis is the primary tool utilized in the design of high-frequency structures. In vast majority of cases, simpler models (e.g., equivalent networks or analytical ones) are either not available or lack accuracy: they can only be used to yield initial designs that need to be further tuned. Consequently, EM-driven adjustment of geometry and/or material parameters of microwave and antenna components is a necessary design stage. This, however, is a computationally expensive process, not only because of a considerable computational cost of high-fidelity EM analysis but also due to a typically large number of parameters that need to be adjusted. In particular, conventional numerical optimization routines (both local and global) may be prohibitively expensive. In this paper, a reduced-cost trust-region-based gradient search algorithm is proposed for the optimization of high-frequency components. Our methodology is based on a smart management of the system Jacobian enhancement which combines: (i) omission of (finite-differentiation-based) sensitivity updates for variables that exhibit small (relative) relocation in the directions of the corresponding coordinate system axes and (ii) selective utilization of a rank-one Broyden updating formula. Parameter selection for Broyden-based updating depends on the alignment between the direction of the latest design relocation and respective search space basis vectors. The proposed technique is demonstrated using a miniaturized coupler and an ultra-wideband antenna. In both cases, significant reduction of the number of EM simulations involved in the optimization process is achieved as compared to the benchmark algorithm (computational speedup of 60% on average). At the same time, degradation of the design quality is minor.
Reduced-cost electromagnetic-driven optimisation of antenna structures by means of trust-region gradient-search with sparse Jacobian updates
- Sławomir Kozieł
- Anna Pietrenko-Dąbrowska
2019 Pełny tekst IET Microwaves Antennas & Propagation
Numerical optimisation plays more and more important role in the antenna design. Because of lack of design-ready theoretical models, electromagnetic (EM)-simulation-driven adjustment of geometry parameters is a necessary step of the design process. At the same time, traditional parameter sweeping cannot handle complex topologies and large number of design variables. On the other hand, high computational cost of the conventional optimisation routines can be reduced using, e.g., surrogate-assisted techniques. Still, direct optimisation of EM simulation antenna models is required at certain level of fidelity. This work proposes a reduced cost trust-region algorithm with sparse updates of the antenna response Jacobian, decided based on relocation of the design variable vector between algorithm iterations and the update history. Our approach permits significant reduction of the optimisation cost (∼40% as compared to the reference algorithm) without affecting the design quality in a significant manner. Robustness of the proposed technique is validated using a set of benchmark antennas, statistical analysis of the algorithm performance over multiple initial designs, as well as investigating the effects of its control parameters that permit control efficiency vs. design quality trade-off. Selected designs were fabricated and measured to validate the computational models utilised in the optimisation process
Reduced-cost surrogate modelling of compact microwave components by two-level kriging interpolation
- Sławomir Kozieł
- Anna Pietrenko-Dąbrowska
2019 ENGINEERING OPTIMIZATION
Full-wave electromagnetic (EM) analysis is a versatile tool for evaluating the performance of high-frequency components. Its potential drawback is its high computational cost, inhibiting the execution of EM-driven tasks requiring massive simulations. The applicability of equivalent network models is limited owing to the topological complexity of compact microstrip components because of EM cross-coupling effects. Development of alternative representations (surrogate models) is therefore necessary. This article proposes a two-level methodology for reliable modelling of compact microstrip components. The keystone is to define the surrogate domain using the first-level model approximating the set of pre-existing reference designs. This limits the volume of the parameter space region that needs to be sampled when constructing the second-level model. The presented approach provides far greater accuracy than conventional methods and is capable of establishing surrogates covering wide ranges of geometric parameters and operating conditions of a particular structure. Applications for parametric optimization are also provided.
Reduction of the Velocity Impact on the Magnetic Flux Leakage Signal
- Zbigniew Usarek
- Marek Chmielewski
- Leszek Piotrowski
2019 Pełny tekst JOURNAL OF NONDESTRUCTIVE EVALUATION
The velocity effect on the magnetic flux leakage (MFL) signal was investigated in this paper. Experiments were performed for velocity of the MFL tool within the range of 0–2 m/s. The velocity was not constant during each measurement to imitate real operational conditions of the MFL tool. Two components of the leakage were measured, i.e. the tangential to the motion direction (x) and the normal to the investigated surface (z). In addition to them, the gradient of the normal component in xdirection was measured with the use of two adjacent sensors. The normal component was found to be the most sensitive to the velocity effect. It was shown that the baseline value of the normal component is proportional to the velocity. An empirical compensation scheme was formulated, and it was used to minimize distortions of the normal component caused by the veloc-ity effect. The finite element method was used to study the distribution of velocity-induced eddy currents in the investigated plate. It was stated that eddy currents generated below the poles lead to a change of plate magnetization as well as to a change of magnetic field distribution above the top surface of the plate, what is observed as a shift of the MFL signal baselines.
Redukcja liczby przełączeń tranzystorów w falowniku kaskadowym z wektorową modulacją szerokości impulsów
- Arkadiusz Lewicki
- Janusz Szewczyk
- Zbigniew Krzemiński
- Marcin Morawiec
2019
W artykule zaprezentowano metody ograniczania liczby przełączeń tranzystorów wybranych mostków kaskadowego falownika napięcia z wektorową modulacją szerokości impulsów. Zaproponowane rozwiązanie umożliwi sterowanie temperaturą poszczególnych mostków H przekształtnika, w którym ten sam strumień powietrza wykorzystano do chłodzenia kilku mostków H. Zmiana liczby przełączanych tranzystorów nie wpływa na dokładność formowania napięć wyjściowych oraz nie ogranicza możliwości utrzymania równomiernego rozkładu napięcia na kondensatorach obwodów DC
Reexamination of the decoherence of spin registers
- Jan Tuziemski
- Aniello Lampo
- Maciej Lewenstein
- Jarosław K. Korbicz
2019 Pełny tekst PHYSICAL REVIEW A
We revisit the decoherence process of a multiqubit register interacting with a thermal bosonic bath. We generalize the previous studies by considering not only the register’s behavior but also a part of its environment. In particular, we are interested in information flow from the register to the environment, which we describe using recently introduced multipartite quantum state structures called spectrum broadcast structures. Working in two specific cases of (i) two-qubit register and (ii) collective decoherence, we identify the regimes where the environment acquires almost complete information about the register state. We also study in more detail the interesting causal aspects related to the finite propagation time of the field disturbances between the qubits. Finally, we describe quantum state structures which appear due to the presence of protected spaces.
Reference-free determination of debonding length in reinforced concrete beams using guided wave propagation
- Beata Zima
- Rafał Kędra
2019 CONSTRUCTION AND BUILDING MATERIALS
This paper presents theoretical and experimental investigations of guided wave propagation in reinforced concrete beams, with pre-existing debonding between steel rebars and concrete blocks, for the purpose of damage detection. The primary aim of these investigations was a detailed analysis of the possible applications of wave propagation in single and multiple debonding detection in reinforced concrete structures and reference-free determination of their total length. Guided waves were excited and measured with the use of piezoelectric sensors in reinforced concrete beams with varying debonding lengths between steel rebars and concrete cover. The influence of damage on wave propagation velocity in both debonded and fully bonded rods was investigated. The effectiveness of the proposed debonding length determination method, which takes advantage of the fastest mode velocity in concrete specimen, was confirmed experimentally.
Regional quality contests based on business excellence models – Pomeranian case study
- Piotr Grudowski
- Anna Wendt
- Ewa Marjańska
2019 Pełny tekst Problemy Jakości
Competitions based on models of organizational excellence have significant potential. Organizations participating in these initiatives have the chance not only to get marketing benefits, but also gain comprehensive knowledge about their management systems. Moreover, thanks to the structure of models of excellence an organization can plan in detail the improvement activities in its main processes. The aim of the authors is to analyze and assess the conditions accompanying competitions for quality awards based on organizational excellence models implemented at the regional level. On the basis of in-depth interview and source materials of Pomerania case study a diagnosis of the current status of this project was presented and the most important problems have been identified. The results can be helpful to improve these types of projects, develop the framework of a new comprehensive system of such competitions in Poland and increase their rank in promoting a pro-quality approach.
Regulacje prawne odnoszące się do testowania samochodów autonomicznych na drogach publicznych w Polsce i w Kalifornii
- Łukasz Jarocki
- Karol Jurczenia
2019 Pełny tekst ZESZYTY NAUKOWE UNIWERSYTETU RZESZOWSKIEGO SERIA PRAWNICZA
The current level of technological advancement allows for predicting that in the near future autonomous technology may be successfully used for the production of self-driving cars. Many companies (not necessarily related to the automotive sector) have spotted the chance of future profits and thus started working on testing and development of autonomous vehicles. The initiation of work has indicated the lack of possibility to test such vehicles on public roads. Several US states have taken active steps to develop and adopt legal regulations enabling testing of autonomous cars on public roads. One of the first states that introduced such regulations was California. Following the new legislative trends, in 2018, Poland adopted the Electromobility and Alternative Fuels Act, which allows for testing autonomous cars on public roads in Poland starting from 1 July 2019. This article aims to compare the newly introduced Polish Act with the Californian Regulations, which were a subject of case law and amendments based on past experience. The article intends to present the Californian legal institutions that could be used by the Polish legislator in future amendments of the Polish Act.
Regularized Local Multivariate Reduced-Order Models With Nonaffine Parameter Dependence
- Martyna Mul
- Valentin de la Rubia
- Grzegorz Fotyga
- Adam Lamęcki
- Michał Mrozowski
2019 Pełny tekst IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES
This paper addresses a singular problem, not yet discussed in the literature, which occurs when parametric reduced-order models are created using a subspace projection approach with multiple concatenated projection bases. We show that this technique may lead to the appearance of localized artifacts in the frequency characteristics of a system, even when the reduced-order projection basis is rich enough to describe the original system. These artifacts are found to be related to nonphysical poles of the transfer function that emerge whenever more than one projection basis is used, each spanning is a similar space, and these bases are directly put together to build multivariate reduced-order models. These unwanted poles are identified using the Bauer–Fike theorem and then the parametrized reduced-order model is regularized with a simple deflation procedure that completely removes the artifacts due to nonphysical resonances from the circuit characteristics. Finally, real-life numerical examples illustrate the accuracy and abilities of the proposed approach.
Regulated Assembly of LPS, Its Structural Alterations and Cellular Response to LPS Defects
- Gracjana Klein-Raina
- Satish Raina
2019 Pełny tekst INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES
Distinguishing feature of the outer membrane (OM) of Gram-negative bacteria is its asymmetry due to the presence of lipopolysaccharide (LPS) in the outer leaflet of the OM and phospholipids in the inner leaflet. Recent studies have revealed the existence of regulatory controls that ensure a balanced biosynthesis of LPS and phospholipids, both of which are essential for bacterial viability. LPS provides the essential permeability barrier function and act as a major virulence determinant. In Escherichia coli, more than 100 genes are required for LPS synthesis, its assembly at inner leaflet of the inner membrane (IM), extraction from the IM, translocation to the OM, and in its structural alterations in response to various environmental and stress signals. Although LPS are highly heterogeneous, they share common structural elements defining their most conserved hydrophobic lipid A part to which a core polysaccharide is attached, which is further extended in smooth bacteria by O-antigen. Defects or any imbalance in LPS biosynthesis cause major cellular defects, which elicit envelope responsive signal transduction controlled by RpoE sigma factor and two-component systems (TCS). RpoE regulon members and specific TCSs, including their non-coding arm, regulate incorporation of non-stoichiometric modifications of LPS, contributing to LPS heterogeneity and impacting antibiotic resistance.
REGULATION OF CELLULAR REDOX HOMEOSTASIS BY (-)-EPICATECHIN AND COCOA EXTRACTS – PILOT STUDY
- Vanja Todorović
- Monika Baranowska
- Sladana Sobajić
- Agnieszka Bartoszek-Pączkowska
2019 Pełny tekst Proceedings
Cocoa polyphenols play an important role in protection against diseases in which oxidative stress is implicated as a causal or contributing factor. The main aim of this study was to elucidate the influence of different cocoa extracts and main cocoa bioactive compound (–)-epicatechin on cell growth and support of antioxidant cellular barrier in colon adenocarcinoma cell line model (HT29). Results show that the tested cocoa bioactivity results from concerted interactions between epicatechin and other components. Hence, cocoa is a very good example which supports the food synergy concept that is attracting growing interest.
Regulation of Cellular Redox Homeostasis by (–)-Epicatechin and Cocoa Extracts—A Pilot Study
- Vanja Todorović
- Monika Baranowska
- Sladana Sobajić
2019 Proceedings
Cocoa polyphenols play an important role in protection against diseases in which oxidative stress is implicated as a causal or contributing factor. The main aim of this study was to elucidate the influence of different cocoa extracts and main cocoa bioactive compound (–)-epicatechin on cell growth and support of antioxidant cellular barrier in colon adenocarcinoma cell line model (HT29). Results show that the tested cocoa bioactivity results from concerted interactions between epicatechin and other components. Hence, cocoa is a very good example which supports the food synergy concept that is attracting growing interest.