2021 - Repozytorium publikacji - Politechnika Gdańska

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Gustav Oelsners Werk aus polnischer Perspektive. das Erbe der moderne in der polnischen Architektur und Stadtplannung
- Gabriela Rembarz
2021
Die Leistungen des Architekten Gustav Oelsner sind ein Beispiel für das gemeinsame Erbe der Region, das gemeinsam betrachtet werden sollte – ohne eine de facto künstliche Aufteilung in die Aktivitäten deutscher und polnischer Künstler. Eine solche Herangehensweise ist notwendig bei der Analyse der Biographie nicht nur des Altonaer Architekten, sondern vieler anderer, die das Schicksal der Geschichte in die nationale Einteilung einordneten und damit das Wissen um ihre Leistungen auf recht hermetischen Forschungsgebieten schlossen. Oelsners Werk kann ein wertvoller Leitfaden sein, der sowohl die Besonderheiten der modernistischen Architektur der Zwischenkriegszeit in Deutschland als auch in Mittel- und Osteuropa vorstellt. Die Publikation beschreibt das Schicksal des modernistischen Erbes in Polen vor dem Hintergrund der politischen Bedingungen des 20. Jahrhunderts. Die Bezüge der Architekten zu zeitgenössischen Herausforderungen dieser Zeit machen die Biografien progressiver Stadtarchitekten der Zwischenkriegszeit zu einer äußerst aktuellen Inspiration angesichts der zeitgenössischen Herausforderungen, nicht nur in Polen.
GVC and wage dispersion. Firm-level evidence from employee-employer database
- Dagmara Nikulin
- Joanna Wolszczak-Derlacz
- Aleksandra Parteka
2021 Pełny tekst EQUILIBRIUM Quarterly Journal of Economics and Economic Policy
Research background: Wage inequalities are still part of an interesting policy-oriented research area. Given the developments in international trade models (heterogeneity of firms) and increasing availability of micro-level data, more and more attention is paid to wage differences observed within and be-tween firms. Purpose of the article: The aim of the paper is to address the research gap concerning limited cross-country evidence on a nexus of wage inequality–global value chains (GVCs), analysed from the perspective of wage inequality components within and between firms. Methods: This paper uses a large employee–employer database derived from the European Structure of Earnings Survey (SES), combined with sector-level indicators of GVC involvement based on the World Input-Output Database (WIOD). As a result, a rich database covering more than 7.5 million observations is created. The regression-based decomposition modelling technique developed by Fiorio and Jenkins (2010) is used to identify the contributions of different factors to wage inequalities, focusing on the components within and between firms. Findings & value added: The analysis presented in this paper aimed to show the contribution of GVC involvement, among various other factors, to the observed inequality of wages. Due to the use of a rich database that merges employer and employee data, the effects materialised with respect to different types of wages could be analysed separately, in particular components between and within firms. The general conclusion from the regression-based decomposition in log wages is that GVCs contribute marginally to the observed wage inequality in the European sample analysed in this paper. Some differences confronting the components within and between firms (the latter dominates) are observed; there is also certain intra sample heterogeneity in the estimated results (e.g. due to sector type or country group), but the general result is robust.
Health System Efficiency in European Countries: Network Data Envelopment Analysis Approach
- Justyna Kujawska
2021 Pełny tekst European Research Studies Journal
Purpose: The article's main aim is to investigate the effectiveness of health systems in European countries based on EUROSTAT data. A comparative analysis of the health systems' effectiveness in different countries is based on their improvement (reform), using the best practices approach. Design/Methodology/Approach: The network DEA model and a slack-based model (NDEA – SBM) are used. A non-oriented model is used. The research sample covers 30 countries (28 EU plus Norway and Island). The health system considers two factors: lifestyle (LF) and primary medical care resources (MC). Lifestyle factors included, alcohol consumption, smoking, and being overweight. The primary resources of medical care are medical personnel, hospital beds, and finances. The subjective assessment of health status and healthy life expectancy is taken as direct outputs. As an intermediate product (link), the expenditure on prevention is assumed as a percentage of GDP. Findings: Health systems in five countries are identified as fully efficient. These countries have also achieved total efficiency for both divisions, lifestyle factors and medical care. The average efficiency of health systems for all countries is low and amounts to 0.619, and the average efficiency for the LF division is 0.580, with huge variations between countries. In the MC division, the average efficiency for all countries is 0.72. However, the difference between countries is more minor. For inefficient countries, the projection of necessary changes to achieve total efficiency has been calculated. Practical Implications: The network DEA model allows a better understanding of the functioning of the complex health care system by analyzing the effectiveness of two separate areas (lifestyle and health care). The values of the forecasted variables are also determined, inputs, outputs, and the linking variable that may help determine priority actions in the field of improving the efficiency of health systems. Originality/value: This paper contributes to the literature by applying the network model to assess the effectiveness of health systems. It enables simultaneous research of various areas related to health. Few publications have attempted to use the network model in the area of health protection.
Heat exchange enhancement of jet impingement cooling with the novel humped-cone heat sink
- Marcin Froissart
- Paweł Ziółkowski
- Waldemar Dudda
- Janusz Badur
2021 Pełny tekst Case Studies in Thermal Engineering
Jet impingement cooling technology is applicable to control temperature of devices, where very high heat flux is generated within a small area. This paper is about the improvement of the jet impingement cooling efficiency by the heat sink geometry modification. Two reference cases were sourced from the literature – flat heat sink and modified one with cone in the jet stagnation region. Such a change improves cooling capability by more than 10%. Presented thermal fluid-solid interaction numerical results are focused to understand better the physics of that improvement and proposed the next step of shape optimization. Two geometrical parameters were investigated – cooling channel’s height and cone’s side wall deformation radius. That includes twenty radiuses for each of three heights. Together with two reference cases, sixty-two shapes were analysed. Such extensive parametrical study was possible thanks to the usage of 2D axisymmetric model, which very well matched to the referenced 3D analysis and experiment. It was concluded, that cone deformation impact varies with the cooling channel’s height. For the optimum geometrical configuration, 11% cooling capability improvement was concluded in comparison to the reference flat surface (8% due to the channel height’s reduction and 3% due to the cone’s deformation).
HEAVE MOTION OF A VERTICAL CYLINDER WITH HEAVE PLATES
- Ewelina Ciba
2021 Pełny tekst Polish Maritime Research
The shape of a vertical cylinder resembles the classic form of a spar platform. Spar platforms are floating platforms that are successfully used in waters of great depths and have several advantages that mean they are readily used in the oil industry. Many of these advantages are also relevant to their application for offshore wind turbines, which is currently being considered. In the hydrodynamic analysis of spar platforms, the determination of their hydrodynamic coefficients plays an important role. They can be determined based on the free decay test. The study presents a method for determining the hydrodynamic coefficients of an object based on the free decay test. The results of free oscillation calculations with the help of numerical fluid mechanics tools are presented and compared with the results of the experiment and analytical solution. The application of determined coefficients and their significance for floating platforms are discussed. The influence of change in the form of an additional damping element on the behaviour of spar structures is shown.
Heavy metal accumulation and distribution in Phragmites australis seedlings tissues originating from natural and urban catchment
- Nicole Nawrot
- Ewa Wojciechowska
- Karolina Matej-Łukowicz
- Jolanta Walkusz-miotk
- Ksenia Pazdro
2021 Pełny tekst ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH
The retention of heavy metal (HM) was studied in root and rhizomes (BLG), stems (ST), and leaves (LF) of Phragmites australis (common reed) seedlings collected from different locations, differing in the scale of anthropogenic interference. The analysis includes the reference samples of sediments in uncontaminated lake Garczonki and contaminated roadside ditch in Cieplewo. The concentrations of Zn, Cu, Pb, Cd, Ni, and Cr were analyzed in plant tissues and sediments using the atomic absorption spectrometry and inductively coupled plasma mass spectrometry. The general assessment of sediments collected in the Garczonki lake showed a good environmental status; while in the roadside ditch in Cieplewo, the sediments were considerably polluted with HM. In the first stage of plant growth, all of the analyzed HMs are mainly inhibited by BLG system. The decreasing trend of elements was as follows: BLG > ST > LF. The organs followed different decreasing trends of HM concentration; the trend Zn > Cu > Ni > Cr > Pb > Cd was found in ST and LF for the Garczonki lake seedlings and for BLG and LF for the roadside ditch in Cieplewo seedlings. Zn showed the highest concentration, while Cd the lowest concentration in each of the examined organs. The bioaccumulation factor indicated the higher mobility of HM in seedlings in the Garczonki lake than in the roadside ditch in Cieplewo. The morphological studies suggest the good state and health of seedling from both sites; however, the reduction of root hair surface was observed for the roadside ditch seedlings. The anatomical studies present changes in the size of the nucleus and count of chloroplasts in LF. No reaction on HM contamination sediments in the seedlings from the roadside ditch in Cieplewo in the aerenchyma was noted. Potentially, both types of seedlings can be used to decontaminate environments rich in HM. However, the level of HM absorbed by seedlings (in the first stage of growth) should be considered due to the behavior in the target phytoremediation site.
Helium-assisted, solvent-free electro-activation of 3D printed conductive carbon-polylactide electrodes
- Maciej Jerzy Głowacki
- Mateusz Cieślik
- Mirosław Sawczak
- Adrian Koterwa
- Iwona Kaczmarzyk
- Rafał Jendrzejewski
- Łukasz Szynkiewicz
- Tadeusz Ossowski
- Robert Bogdanowicz
- Paweł Niedziałkowski
- Jacek Ryl
2021 APPLIED SURFACE SCIENCE
Fused filament fabrication is one of the most rapidly developing 3D printing techniques, with numerous applications, including in the field of applied electrochemistry. Here, the utilisation of conductive carbon black polylactic acid (CB-PLA) for 3D printouts is the most promising. To use CB-PLA as an electrode material, an activation process must be performed, removing the polymer matrix and uncovering the electrically conductive filler. We present a novel, alternative approach towards CB-PLA activation with Nd:YAG (λ = 1064 nm) laser ablation. We present and discuss the activation efficiency based on various laser source operating conditions, and the gas matrix. The XPS, contact angle, and Raman analyses were performed for evaluation of the surface chemistry and to discuss the mechanism of the activation process. The ablation process carried out in an inert gas matrix (helium) delivers a relatively high electrochemically active surface area of the CB-PLA electrode, while the resultant charge transfer process is hindered when activated in the air plausibly due to the formation of thermally induced oxide layers. The electroanalytical performance of laser-treated CB-PLA in a He atmosphere was confirmed through caffeine detection, offering detection limits of 0.49 and 0.40 μM (S/N = 3) based on CV and DPV studies, respectively.
Hidden Champions of Poland
- Grażyna Leśniak- Łebkowska
- Magdalena Popowska
- Małgorzata Godlewska
- Mirosław Łukasiewicz
2021 Pełny tekst
Poland is a country with a strong entrepreneurial spirit. The hidden champions’ performance has been closely related to political and economic changes: the fall of communism in 1989 and the transition from a centrally planned economy to a market economy. This led to the emergence of small private businesses focused on the domestic market. The accession to the European Union in 2004 created new perspectives for the hidden champions’ growth after the opening of the international markets, financial, educational, and institutional support, legal regulations, and FDI inflow with new technologies. Liberal democracy enabled the hidden champions to emerge in almost all industries. The majority of them have been taken over by large international companies. This has enabled their high performance. In the Global Competitiveness Index, Poland moved from 57th position in 2011 to 37th in 2018. Polish hidden champions build their positions using strong partnerships with suppliers and customers. Their competitive position is weaker than that of leading Western companies due to Poland’s less developed business culture and the complexity of regulations increasing the transaction costs and business risks. Hidden champions go international with their products and services and are masters in securing their access to scarce resources. They offer strongly innovative products based on their own R&D and develop their brands and new distribution channels, such as e-commerce and digital marketing. Poland is one of the world’s leaders in the business services sector and provides a friendly environment to start-ups.
Hierarchical 2-step neural-based LEGO bricks detection and labeling
- Tomasz Boiński
2021 Pełny tekst
LEGO bricks are extremely popular and allow the creation of almost any type of construction due to multiple shapes available. LEGO building requires however proper brick arrangement, usually done by shape. With over 3700 different LEGO parts this can be troublesome. In this paper, we propose a solution for object detection and annotation on images. The solution is designed as a part of an automated LEGO bricks arrangement. The proposed approach consists of 2 stages – object detection and labeling. The paper discusses different approaches and points out a final model. A 2-step, hierarchical model and the results are presented. An evaluation of the proposed solution is also given.
High load capacity spur gears with conchoidal path of contact
- Pavlo Tkach
- Pavlo Nosko
- Oleksandr Bashta
- Yurii Tsybrii
- Oleksii Nosko
2021 Pełny tekst Mechanics & Industry
The present study is devoted to investigation of spur gears with a conchoidal path of contact and a convex-convex contact between teeth. The load capacity and energy efficiency were evaluated using both theoretical and experimental approaches. The theoretical analysis showed that the conchoidal gear pairs are 5–21% stronger in terms of contact stress and have similar energy efficiency as compared to the involute gear pairs of the same configuration. Experiments were conducted on a gear test rig. Its energy efficiency was determined by measuring the active power of the motor driving the pinion shaft and controlling the torque at the gear shaft. The load capacity of the tested gear pair was estimated by analysing changes in the energy efficiency. It was found that the conchoidal gear pair has more than 20% higher load capacity and slightly higher energy efficiency, which agrees well with the mentioned theoretical results. Thereby, the study concludes a substantially higher load capacity of the conchoidal gears compared to the traditional involute ones.
High Performance Control of AC Drives with Matlab/ Simulink
- Abu-rub Haitham
- Atif Iqbal
- Jarosław Guziński
2021
Explore this indispensable update to a popular graduate text on electric drive techniques and the latest converters used in industry. The Second Edition of High Performance Control of AC Drives with Matlab®/Simulink delivers an updated and thorough overview of topics central to the understanding of AC motor drive systems. The book includes new material on medium voltage drives, covering state-of-the-art technologies and challenges in the industrial drive system, as well as their components, and control, current source inverter-based drives, PWM techniques for multilevel inverters, and low switching frequency modulation for voltage source inverters. This book covers three-phase and multiphase (more than three-phase) motor drives including their control and practical problems faced in the field (e.g., adding LC filters in the output of a feeding converter), are considered. The new edition contains links to Matlab®/Simulink models and PowerPoint slides ideal for teaching and understanding the material contained within the book. Readers will also benefit from the inclusion of: - A thorough introduction to high performance drives, including the challenges and requirements for electric drives and medium voltage industrial applications - An exploration of mathematical and simulation models of AC machines, including DC motors and squirrel cage induction motors - A treatment of pulse width modulation of power electronic DC-AC converter, including the classification of PWM schemes for voltage source and current source inverters - Examinations of harmonic injection PWM and field-oriented control of AC machines - Voltage source and current source inverter-fed drives and their control - Modelling and control of multiphase motor drive system Supported with a companion website hosting online resources. Perfect for senior undergraduate, MSc and PhD students in power electronics and electric drives, High Performance Control of AC Drives with Matlab®/Simulink will also earn a place in the libraries of researchers working in the field of AC motor drives and power electronics engineers in industry.
High temperature corrosion evaluation and lifetime prediction of porous Fe22Cr stainless steel in air in temperature range 700–900 °C
- Damian Koszelow
- Małgorzata Makowska
- Jakub Karczewski
- Piotr Jasiński
- F. Marone
- Sebastian Molin
2021 Pełny tekst CORROSION SCIENCE
This work describes a high temperature corrosion kinetics study of ~30% porous Fe22Cr alloys. The surface area of the alloy (~0.02 m2 g-1) has been determined by tomographic microscopy. The weight gain of the alloys was studied by isothermal thermogravimetry in the air for 100 hours at 700 - 900 °C. Breakaway oxidation was observed after oxidation at 850 °C (~100 hours) and 900 °C (~30 hours). The lifetime prediction shows the investigated porous alloy can be used for >3000 hours at temperatures <700 °C. At temperatures ≥700 °C, the lifetime of the porous alloy is limited by the available chromium reservoir.
High temperature proton conduction in LaSbO4
- Piotr Winiarz
- Aleksandra Mielewczyk-Gryń
- Kacper Dzierzgowski
- Maria Gazda
- Sebastian Wachowski
2021 Pełny tekst CHEMISTRY-A EUROPEAN JOURNAL
Lanthanum orthoantimonate was synthesized using a solid‐state synthesis method. To enhance the possible protonic conductivity, samples with the addition of 1 mol% Ca in La‐site, were also prepared. The structure was studied by the means of X‐ray diffraction, which showed that both specimens were single phase. The materials crystallized in the space group P2 1 /n. Dilatometry revealed that material expands non‐linearly with the temperature. The nature of this deviation is unknown, however, the calculated linear fraction thermal expansion coefficient was 9.56×10 ‐6 1/K. Electrical properties studies showed that the material is a proton conductor in oxidizing conditions, which was confirmed both by temperature studies in wet in dry air, but also by the H/D isotope exchange experiment. The conductivity was rather modest, peaking at order 10 ‐6 S/cm at 800°C, but this can be further improved by microstructure and doping optimization. This is the first time when protonic conductivity in lanthanum orthoantimonates is reported.
High-accuracy computation of hard X-ray focusing and imaging for refractive optics
- Paweł Wojda
- Sergey Kshevetskii
- Ivan Lyatun
2021 Pełny tekst JOURNAL OF SYNCHROTRON RADIATION
A mathematical apparatus for solving problems of X-ray wave propagation through complex optical systems, when the lens thickness can change with jumps, is developed and presented. The developed method is based on the use of the superposition of oriented Gaussian beams, which satisfy the Helmholtz equation with high accuracy. The wave propagation in air and through kinoform and ordinary lenses is considered. Focusing and imaging properties are compared for both types of X-ray optics. The diffraction effects arising due to thickness jumps in the kinoform lenses and the influence of these jumps on the X-ray focusing and imaging are investigated. The prospect of using the developed theory for X-ray optics applications is discussed.
High-accuracy polarimetric studies on lead germanate single crystals
- Mykola Shopa
- Nazar Ftomyn
- Yaroslav Shopa
2021 Journal of Applied Crystallography
A high-accuracy polarimetric technique has been used for the characterization of a lead germanate ferroelectric single crystal. The measurement results of the linear and circular birefringence in the [010] direction at a wavelength of 633 nm under the influence of an electric field are presented. Gyration–electric field hysteresis loops at alternative crystal positions in the polarization system have been used to determine the ellipticity of the eigenwaves. A temperature dependence of the gyration tensor component g11 in the temperature range of 300–450 K was found.
Higher responsiveness to rosuvastatin in polygenic versus monogenic hypercholesterolaemia: a propensity score analysis
- Mariusz Kaszubowski
2021 EUROPEAN HEART JOURNAL
Background The underlying monogenic defect in familial hypercholesterolemia (FH) can be detected in ∼40% of cases. The majority of mutation-negative patients have a polygenic cause of high LDL-cholesterol (LDL-C) due to having inherited a greater than average number of common LDL-C raising single nucleotide polymorphisms (SNPs). Purpose We sought to investigate, whether the monogenic or polygenic defect in FH is associated with the response to rosuvastatin. Methods Individuals with a clinical diagnosis of FH were tested for mutations in LDLR and APOB genes. A previously established LDL-C-specific polygenic risk score (PRS) was used to examine the possibility of polygenic hypercholesterolemia in mutation negative patients. The propensity score analysis was performed to evaluate the variables associated with the response to rosuvastatin. The type of hypercholesterolemia (polygenic or monogenic) and following variables: age, gender, LDL-baseline, statin intolerance, ezetimibe use, rosuvastatin dose, diabetes and cardiovascular disease (CVD), were examined to minimize the bias of this observational study. Results LDLR/APOB mutation was found in 47 (42%) patients, whereas polygenic hypercholesterolemia was diagnosed in 65 (58%) of patients. Mean age was comparable in both groups (54±13 vs 51±13, p=0.134). CVD was diagnosed in ≈26% of individuals in both cohorts (p=0.343). There was no difference in the distribution of CV risk factors, such as arterial hypertension, smoking, diabetes, body mass index and in rate of statin intolerance. Monogenic subjects had higher baseline LDL-C compared to polygenic (Table 1). Adjusted model showed a lower percentage of change in LDL-C after rosuvastatin treatment in monogenic vs. polygenic subjects (46% vs 55%, p<0.001) (Figure 1). The probability of achieving LDL-C targets in monogenic FH was lower than in polygenic subjects (0.075 vs. 0.245, p=0.004). Polygenic patients were more likely to achieve LDL-C goals, compared to mutation-positive patients (OR 3.28; 95% CI:1.23–8.72). Conclusion Our findings indicate an essentially higher responsiveness to rosuvastatin in patients with a polygenic cause, as compared to those carrying monogenic mutations.
High-Gain Compact Circularly Polarized X-Band Superstrate Antenna for CubeSat Applications
- Luiza Leszkowska
- Mateusz Rzymowski
- Krzysztof Nyka
- Łukasz Kulas
2021 Pełny tekst IEEE Antennas and Wireless Propagation Letters
In this letter, a concept of high-gain circularly polarized X-band antenna employing a partially reflecting surface (PRS) has been presented. In the initial antenna analysis, the influence of parasitic elements size in the PRS structure on antenna radiation pattern parameters has been investigated and the optimal arrangement of the elements has been identified. The proposed antenna provides wide bandwidth of return loss above 10 dB of 20% (8-9.8 GHz) and circular polarization in a frequency range 8.35-8.95 GHz. The final design is compact (62 × 62 × 22.2 mm) and lightweight (29.7 g), which makes it suitable for use in CubeSat X-band communication systems but also drone and high-altitude pseudo-satellite (HAPS) applications.
Highlighting interlanguage phoneme differences based on similarity matrices and convolutional neural network
- Grazina Korvel
- Povilas Treigys
- Bożena Kostek
2021 Pełny tekst Journal of the Acoustical Society of America
The goal of this research is to find a way of highlighting the acoustic differences between consonant phonemes of the Polish and Lithuanian languages. For this purpose, similarity matrices are employed based on speech acoustic parameters combined with a convolutional neural network (CNN). In the first experiment, we compare the effectiveness of the similarity matrices applied to discerning acoustic differences between consonant phonemes of the Polish and Lithuanian languages. The similarity matrices built on both an extensive set of parameters and a reduced set after removing high-correlated parameters are used. The results show that higher accuracy is obtained by the similarity matrices without discarding high-correlated parameters. In the second experiment, the averaged accuracies of the similarity matrices obtained are compared with the results provided by spectrograms combined with CNN, as well as the results of the vectors containing acoustic parameters and two baseline classifiers, namely k-nearest neighbors and support vector machine. The performance of the similarity matrix approach demonstrates its superiority over the methods used for comparison.
Highly crystalline colloidal nickel oxide hole transport layer for low-temperature processable perovskite solar cell
- Pei-Huan Lee
- Ting-Tzu Wu
- Chia-Feng Li
- Damian Głowienka
- Yi-Hsuan Sun
- Yi-Ting Lin
- Hung-Wei Yen
- Cheng-Gang Huang
- Yulia Galagan
- Yu-Ching Huang
- Wei-Fang Su
2021 Pełny tekst CHEMICAL ENGINEERING JOURNAL
Highly crystalline NiOX usually requires high annealing temperature (>300 °C) which is incompatible with flexible substrate and might consume high amount of energy. Herein, we demonstrate a facile emulsion process to synthesize highly crystalline, low temperature deposition (<150 °C) and solution processable NiOx nanoparticles (NPs) as a hole transport layer for the perovskite solar cells (PVSCs). A novel surfactant of tetramethylammonium hydroxide (TMAOH) was used to react with Ni(NO3)2 to form Ni(OH)2 nanoparticles (NPs). The micelles of TMAOH act as a nano-reactor containing OH− anion. The Ni+ cation enters into the nano-reactor to form Ni(OH)2 NPs inside the reactor with controlled particle size. The Ni(OH)2 NPs prepared by emulsion process are further calcined to form NiOX NPs with the particle size of 8.28 ± 2.64 nm (EP-NiOX). The smaller size of EP-NiOX NPs results in a good dispersibility and an excellent stability of NPs suspension, which can be used to fabricate uniform NiOX film without any aggregates. A power conversion efficiency (PCE) of 18.85% can be achieved using this EP-NiOX film, as compared with 16.68% using the NiOX NPs synthesized from the chemical precipitation method (CPM-NiOX). Moreover, a flexible PVSCs with a PCE of 14.28% can be fabricated using the EP-NiOX film. Except for the device performance, the quality of the EP-NiOX film shows a good batch-to-batch uniformity, resulting in an excellent reproducibility of PVSCs. This work has a potential for the development of a large-scale production of PVSCs with a high energy conservation.
Highly Dissipative Materials for Damage Protection against Earthquake-Induced Structural Pounding
- Anna M. Stręk
- Natalia Lasowicz
- Arkadiusz Kwiecień
- Bogusław Zając
- Robert Jankowski
2021 Pełny tekst Materials
It is a common situation that seismic excitations may lead to collisions between adjacent civil engineering structures. This phenomenon, called earthquake-induced structural pounding, may result in serious damage or even the total collapse of the colliding structures. Filling the gap between two buildings erected close to one another by using visco-elastic materials can be considered to be one of the most effective methods to avoid seismic pounding. In this paper, a new polymer–metal composite material made of polyurethane and closed-cell aluminum foam is proposed as a pounding energy absorber for protection against earthquake hazards. The composite was created in two versions, with and without an adhesive interface. A series of experiments which reflect the conditions of seismic collision were performed: quasi-static compression, dynamic uniaxial compression and low-cycle dynamic compression with 10 loops of unloading at 10% strain. The composite material’s behavior was observed and compared with respect to uniform material specimens: polymer and metal foam. The experimental results showed that the maximum energy absorption efficiency in the case of the new material with the bonding layer was improved by 34% and 49% in quasi-static and dynamic conditions, respectively, in comparison to a sole polymer bumper. Furthermore, the newly proposed composites dissipated from 35% to 44% of the energy absorbed in the cyclic procedure, whereas the polymer specimen dissipated 25%. The capacity of the maintenance of the dissipative properties throughout the complete low-cycle loading was also satisfactory: it achieved an additional 100% to 300% of the energy dissipated in the first loading–unloading loop.