Publications Repository - Gdańsk University of Technology

Page settings

polski
Publications Repository
Gdańsk University of Technology

Show publications from the year

Publications from the year 2024

Show all
  • Isolation of Human Progenitor Epidermal Cells on Collagen Type IV and Analysis of Their Markers with Flow Cytometry and PCR Methods
    • Milena Deptula
    • Małgorzata Zawrzykraj
    • Paulina Słonimska
    • Michał Pikuła
    2024

    Epidermal stem cells, located in the skin, together with keratinocytes are transplanted in regenerative therapies, e.g., for the treatment of burns or other wounds. Here, we describe the protocol of their enzymatic isolation from human skin. It includes separation of the epidermis form the dermis by incubation with dispase followed by cell isolation for epidermis by digestion with trypsin. Cell isolated with this method can be seeded on collagen IV-coated dishes. The methods of analysis of epidermal stem cells markers (e.g., CD71, CD29) with flow cytometry and RT-PCR are also included.

  • Isothermal turbines − New challenges. Numerical and experimental investigations into isothermal expansion in turbine power plants
    • Krzysztof Kosowski
    • Marian Piwowarski
    • Marcin Richert
    • Robert Stępień
    • Wojciech Włodarski
    2024 ENERGY CONVERSION AND MANAGEMENT

    The efficiency of power plants with steam or gas turbines depends on the efficiencies of a thermodynamic cycle and devices implementing this cycle. In the case of high power outputs, we cannot expect a significant increase in the efficiency of individual devices. Therefore, what remains is to increase the efficiency of the implemented thermodynamic cycle - the complex Rankine cycle in the case of steam turbines or the extended Brayton cycle in gas turbine units. The efficiencies of these cycles depend on the hot reservoir temperatures, limited by the materials used. The solution seems to be the thermodynamic cycles with the highest efficiency within given temperature limits, the „generalized Carnot cycles”. About gas turbines, such a cycle is the Ericsson cycle. The most difficult element of this cycle is carrying out high-temperature expansion. So far, there is no literature data on a technical device implementing this process. In this article, we present a method for designing turbine nozzles for isothermal expansion and the results of experimental tests of the first isothermal turbine. In the case of gas microturbines with a regenerator, isothermal expansion can increase efficiency from 24%-28% up to 36%. An increase in efficiency of several to a dozen percentage points is expected for organic rankine cycle (ORC) turbines. Due to such significant increases in energy generation efficiency, an isothermal turbine may become a future solution for energy systems.

  • Italy, an Extraordinary Commonplace? Stereotypes and Imaginaries of Italianness in Online Communication by Fashion Brands
    • Flavia Piancazzo
    • Alice Noris
    • Nadzeya Sabatini
    • Lorenzo Cantoni
    2024 Fashion Theory: The Journal of Dress, Body & Culture

    The paper explores the use of country-related stereotypes associated with Italian identity in the social media communication of 21 Italian fashion brands on Instagram. Focusing on the concept of “made in Italy”, the research employs image content analysis to identify how the selected sample of brands communicates Italian identity globally. The theoretical framework emphasizes the importance of the Country of Origin (COO) concept, indicating that “made in Italy” extends beyond a manufacturing label to encompass cultural, historical, and esthetic dimensions. The analysis reveals Italian fashion brands’ deliberate use of stereotypes, iconic objects, and cultural references to shape and reinforce Italian identity in their digital communication. It highlights the intertwining of these elements, contributing to a multifaceted narrative that extends beyond product promotion. Moreover, it underscores the role of social media, particularly Instagram, in enabling brands to project their Italian identity globally, perpetuating esthetics associated with the concept of “dolce vita”. The study emphasizes the importance of holistic brand communication and the powerful role of Instagram in shaping and reinforcing the global image of “made in Italy”. It also offers insights on utilizing stereotypes and cultural symbols to enhance brand identity, aligning with perceptions associated with Italian culture.

  • Iterative‐recursive estimation of parameters of regression models with resistance to outliers on practical examples
    • Janusz Kozłowski
    • Zdzisław Kowalczuk
    2024 Full text IET Control Theory and Applications

    Here, identification of processes and systems in the sense of the least sum of absolute values is taken into consideration. The respective absolute value estimators are recognised as exceptionally insensitive to large measurement faults or other defects in the processed data, whereas the classical least squares procedure appears to be completely impractical for processing the data contaminated with such parasitic distortions. Since the absolute value quality index cannot be minimised analytically, an iterative solution is used to find optimal estimates of the parameters of the underlying regression model. In addition, an approximate recursive estimator is proposed and implemented for on-line evaluation of system parameters. The convergence (basic property) of the iterative estimator is show to be proven and some aspects related to the absolute value criterion are explained. This allows for the formulation of practical conclusions and indication of directions for further research. In addition, the effectiveness of the described iterative-recursive estimation procedures is practically verified by appropriate numerical experiments.

  • Jak przystąpić do wdrażania inteligentnych rozwiązań w mieście?
    • Aleksander Orłowski
    • Szymon Ciupa
    • Piotr Hołubowicz
    2024 Full text Wspólnota. Pismo Samorządu Terytorialnego

    Nowa kadencja władz lokalnych to wyjątkowa okazja do wprowadzenia zmian, które mogą przekształcić miasta w inteligentne, zrównoważone i przyjazne do życia. Wdrażanie idei smart city nie tylko poprawia jakość życia, ale również sprzyja rozwojowi gospodarczemu i ochronie środowiska. W artykule przedstawiamy kluczowe rekomendacje dla nowych władz, które pomogą w skutecznej transformacji miast w smart cities.

  • KEMR-Net: A Knowledge-Enhanced Mask Refinement Network for Chromosome Instance Segmentation
    • Ding Chen
    • Haoxi Zhang
    • Edward Szczerbicki
    2024 Full text CYBERNETICS AND SYSTEMS

    This article proposes a mask refinement method for chromosome instance segmentation. The proposed method exploits the knowledge representation capability of Neural Knowledge DNA (NK-DNA) to capture the semantics of the chromosome’s shape, texture, and key points, and then it uses the captured knowledge to improve the accuracy and smoothness of the masks. We validate the method’s effectiveness on our latest high-resolution chromosome image dataset. The experimental results show that our proposed method’s mask average precision (MaskAP) is 3.66% higher than Mask R-CNN and outperforms advanced Cascade Mask R-CNN by 1.35%.

  • Keratinocyte-derived small extracellular vesicles supply antigens for CD1a-resticted T cells and promote their type 2 bias in the context of filaggrin insufficiency
    • Adrian Kobiela
    • Weronika Hewelt-Belka
    • Joanna Frackowiak
    • Natalia Kordulewska
    • Lilit Hovhannisyan
    • Aleksandra Bogucka
    • Rachel Etherington
    • Artur Piróg
    • Irena Dapic
    • Susanne Gabrielsson
    • Sara Brown
    • Graham Ogg
    • Danuta Gutowska-Owsiak
    2024 Full text Frontiers in Immunology

    Introduction: Exosome-enriched small extracellular vesicles (sEVs) are nanosized organelles known to participate in long distance communication between cells, including in the skin. Atopic dermatitis (AD) is a chronic inflammatory skin disease for which filaggrin (FLG) gene mutations are the strongest genetic risk factor. Filaggrin insufficiency affects multiple cellular function, but it is unclear if sEV-mediated cellular communication originating from the affected keratinocytes is also altered, and if this influences peptide and lipid antigen presentation to T cells in the skin. Methods: Available mRNA and protein expression datasets from filaggrin-insufficient keratinocytes (shFLG), organotypic models and AD skin were used for gene ontology analysis with FunRich tool. sEVs secreted by shFLG and control shC cells were isolated from conditioned media by differential centrifugation. Mass spectrometry was carried out for lipidomic and proteomic profiling of the cells and sEVs. T cell responses to protein, peptide, CD1a lipid antigens, as well as phospholipase A2-digested or intact sEVs were measured by ELISpot and ELISA. Results: Data analysis revealed extensive remodeling of the sEV compartment in filaggrin insufficient keratinocytes, 3D models and the AD skin. Lipidomic profiles of shFLGsEV showed a reduction in the long chain (LCFAs) and polyunsaturated fatty acids (PUFAs; permissive CD1a ligands) and increased content of the bulky headgroup sphingolipids (non-permissive ligands). This resulted in a reduction of CD1a-mediated interferon-γ T cell responses to the lipids liberated from shFLG-generated sEVs in comparison to those induced by sEVs from control cells, and an increase in interleukin 13 secretion. The altered sEV lipidome reflected a generalized alteration in the cellular lipidome in filaggrin-insufficient cells and the skin of AD patients, resulting from a downregulation of key enzymes implicated in fatty acid elongation and desaturation, i.e., enzymes of the ACSL, ELOVL and FADS family. Discussion: We determined that sEVs constitute a source of antigens suitable for CD1a-mediated presentation to T cells. Lipids enclosed within the sEVs secreted on the background of filaggrin insufficiency contribute to allergic inflammation by reducing type 1 responses and inducing a type 2 bias from CD1a-restricted T cells, thus likely perpetuating allergic inflammation in the skin.

  • Key success factors for small design offices in the bidding process
    • Magdalena Apollo
    • Daniel Burkacki
    2024 Full text Architectural Engineering and Design Management

    Competition in the design office market is high, therefore it is important to be aware of the conditions determining the competitive advantage, thus increasing the bidding effectiveness. For this reason, the aim of the article is to identify key success factors (KSF) increasing successful bidding of a small design office. The factors were identified and then analysed based on a literature review, expert interviews and using Group Consensus Cluster Analysis (GCCA) – the module of the AHP method clustering a group of decision makers into smaller subgroups with higher consensus. To examine the managerial implications, a KSF analysis was conducted from the perspective of the bidding effectiveness of the selected small design office. The results indicate that ‘technical skills and experience’ is the factor most influencing the potential of a small design office. Nevertheless, the entire proposed procedure provides important guidelines on how to use the organisation's strengths for its development and what needs to be improved in its operation.

  • Kluczowe kompetencje jako narzędzie do tworzenia nowych modeli biznesu w przedsiębiorstwach
    • Kamila Siwak
    2024 Full text

    Koncepcja kluczowych kompetencji wywodzi się z nurtu zasobowego, który zakłada, iż o efektywności i konkurencyjności każdego podmiotu decydują odpowiednio dobrane zasoby i umiejętności ich optymalnego wykorzystania. Model biznesu to narzędzie do realizacji strategii organizacji, które wspomaga rozwój oraz zarządzanie strategiczne w przedsiębiorstwie. Dysertacja wypełnia lukę, jaką było wskazanie na zależność pomiędzy kluczowymi kompetencjami przedsiębiorstwa, a możliwościami kreowania przy ich zastosowaniu nowych modeli biznesu. Główny obszar badań stanowiły zasoby niematerialne przedsiębiorstwa stanowiące źródła pochodzenia kluczowych kompetencji. Kolejny obszar badań to określenie struktury modelu biznesu oraz wskazanie wpływu kluczowych kompetencji na strukturę danego modelu. W badaniu zastosowano metodę gromadzenia danych w postaci wywiadu z perspektywy biograficznej w powiązaniu z obserwacją uczestnicząca badaczki oraz netnografię. Efektem badań było opracowanie zbioru dziewięciu kluczowych kompetencji organizacji oraz zestawu wskaźników finansowych i niefinansowych pozwalających ocenić funkcje kluczowych kompetencji, określono istotę modelu biznesu oraz wskazano oddziaływanie kluczowych kompetencji na jego strukturę. Praktycznym wkładem dysertacji są opracowane schematy, mogące stanowić wsparcie dla liderów przedsiębiorstw w ocenie prowadzonej działalności biznesowej.

  • Kłamliwe, udane i błędne metafory sztucznej inteligencji chatbotów
    • Jan Kreft
    • Barbara Cyrek
    2024 Full text Roczniki Kulturoznawcze

    W czasach, gdy tzw. sztuczna inteligencja staje się integralną częścią dużych modeli języ-kowych, osobistych asystentów czy np. tzw. inteligentnego domu, coraz ważniejsze staje się po-znanie czynników postaw wobec niej i jej narzędzi. Obserwowany świt nowych możliwości identyfikowanych ze sztuczną inteligencją skłania do lepszego poznania metafor, którymi jest opisywana. Metafory stanowią bowiem nie tylko klucz do wyjaśniania nieznanego, ale mają znaczącą wartość heurystyczną, są fundamentem nowoczesnej racjonalności i mogą wypierać ludzki osąd oraz minimalizować uprzedzenia i krytyczną refleksję. Celem artykułu jest identyfikacja metafor oraz rozpoznanie ich performatywnej roli w dysku-sji o sztucznej inteligencji i jej narzędziach. Przedmiotem badania są występujące w opisach me-diów i nowych technologii metafory dominujące oraz mniej znane metafory chatbotów obecne w tekstach dziennikarskich, na przykładzie artykułów opublikowanych w opiniotwórczym The New York Times. W ramach badania identyfikujemy i analizujemy m.in. metafory „platformy”, „sieci”, „umy-słu jako maszyny” oraz ożywione i nieżywione metafory towarzyszące sztucznej inteligencji i jej aktorów. Badamy ich perswazyjny charakter i cele tej perswazji.

  • Knowledge economics and the demand for higher education
    • Franciszek Kutrzeba
    2024 Full text Journal of Modern Science

    This article suggests that the decreased demand for higher education in Poland is partially caused due to the changes in consumer preferences. The appearance of a cheap and highly accessible form of knowledge offered by the massive open online courses is presumed here to have an effect on the demand for formal higher education. This article proposes an additional perspective to the research on knowledge consumption, especially in the context of different versions of knowledge. A simple supply and demand framework is used. It suggests, that the appearance of a cheaper substitute to knowledge leads to the increase of its consumption. This article also argues that knowledge, in terms of ideas and innovations, is misleadingly called to be non-rival and non-excludable. Overall, the article calls for a broader understanding of the knowledge market, emphasizing the need for higher education institutions to adapt to the evolving landscape of knowledge production and consumption. The rise of imperfect informational capitalism requires us to rethink the importance of knowledge quality to the modern society.

  • Knowledge Management and Resilience in SMEs Sector
    • Krzysztof Zięba
    2024

    Purpose: The aim of this paper is to investigate the role of resilience in surviving major disruptions, such as pandemic or war. This problem is especially vital for small and medium-sized enterprises (SMEs), as they often lack both resources needed for survival during prolonged economic hardship and knowledge management (KM) practices which are useful for developing the necessary business resilience. Methodology: The paper uses literature review approach to investigate the current knowledge on resilience and its dimensions as well as the links between KM, resilience and operational efficiency. Systems Thinking approach is proposed to be used to show the complexity of mechanisms behind those phenomena and the impact they have on business competitiveness in the SMEs sector. Findings: Because of their nature, SMEs were particularly severely hit by the COVID-19 crisis. SMEs now have to adjust to the new reality of the post-crisis phase by developing their business resilience. KM practices prove to offer high potential in resilience creation and resilience maintenance. Specific features of SMEs, if combined with operational agility and resilience, may allow them to successfully face challenges of their turbulent environment.. Research limitations: This paper is of a preliminary, conceptual nature. Its further development includes investigation of various aspects of KM relevant to strengthening business resilience in SMEs. More data is still needed to develop and test full Systems Thinking model based on the framework proposed here. Practical implications: SMEs owners and managers may benefit from this paper, as they may use it as a guidance in the process of developing business resilience in their organisations. The insights provided in this paper may be useful for decision makers and also for businesses offering knowledge-based services, offering them a deeper understanding of the presented phenomena and relations between them.. Originality/value: The paper is focused on SMEs, which are rarely investigated when it comes resilience creation and benefits it offers. The framework presented here provides important insights, which can be useful to numerous stakeholders.

  • Knowledge Sharing and Dynamic Capabilities: Does Gender Matter?
    • Elżbieta Karwowska
    • Wioleta Kucharska
    2024

    Knowledge sharing in organizations is a focal process leading to organizational adaptability and sustainable growth. Dynamic capabilities development is critical for this. Diversity, inclusive culture, and gender balance are seen as factors that also support organizations' development. The question of the role of gender in sharing and using knowledge to initiate change in organizations remains open. This study aims to fill this gap. Based on a survey targeted to Polish knowledge workers (495 cases), our data was analyzed using OLS regression (SPSS PROCESS software ver. 3.4). Our research shows that for a manager position, gender matters for the reconfiguring dynamic capability (DCR) building in the organization, thanks to tacitknowledge sharing (TKS). The results show that female managers support DCR in the organization even if TKS does not support their efforts. If supported, their positive influence on DCR grows but not as fast as observed for men with lower starting skills. So, when holding managerial positions, women lose motivation to support changes. The question that arises is "why"? There are some hypothetical assumptions: it might be that since women worked so hard to earn their managerial positions, they want to secure them and avoid any risks connected to changes. In the particular case presented, women managers' lower willingness to support changes may be also caused by their lower level of self-confidence. However, it might be that the reasons are quite different, thus solving this issue requiresfurther studies. The critical value of the presented research is that it delivers one more proof, this time from the knowledge management (TKS) and change implementation (DCR) perspective, that gender inequality in workplaces has negative consequences for organization.

  • Kriging-assisted hybrid reliability design and optimization of offshore wind turbine support structure based on a portfolio allocation strategy
    • Debiao Meng
    • Hengfei Yang
    • Shiyuan Yang
    • Yuting Zhang
    • Abílio M.P. De Jesus
    • José A.F.O. Correia
    • Tiago Fazeres-Ferradosa
    • Wojciech Macek
    • Ricardo Branco
    • Shun-Peng Zhu
    2024 OCEAN ENGINEERING

    In recent years, offshore wind power generation technology has developed rapidly around the world, making important contributions to the further development of renewable energy. When designing an Offshore Wind Turbine (OWT) system, the uncertainties in parameters and different types of constraints need to be considered to find the optimal design of these systems. Therefore, the Reliability-Based Design Optimization (RBDO) method is usually adopted to ensure the stability and reliability of the design scheme. However, the calculation cost is huge in the RBDO problem considering mixed uncertainties. The Kriging model is a widely used approximation technique to reduce the computational cost in RBDO. However, establishing a sufficiently accurate Kriging model for a complex engineering system often requires the collection of more sample data and more time-consuming performance evaluation. In order to solve this problem, this study proposes a hybrid RBDO method based on a Portfolio allocation strategy. Based on ensuring the accuracy of the Kriging model, this method requires fewer iterations than the previous method of iteratively establishing the Kriging model using the same learning function. Furthermore, the optimal design of the system can be completed in a shorter time. This has great application potential to reduce the time labor and material costs spent in the design process of OWT. Two mathematical examples and two engineering examples are used to verify the accuracy of the method. Then, the proposed method is used in the design and optimization of a typical OWT support structure, showing the method's feasibility and superiority.

  • Lab-in-syringe as a practical technique for automatic microextraction: Evaluation by Blue Applicability Grade Index
    • Natalia Manousi
    • Justyna Płotka-Wasylka
    • Erwin Rosenberg
    • Aristidis Anthemidis
    2024 TRAC-TRENDS IN ANALYTICAL CHEMISTRY

    Lab-in-syringe (LIS) is a powerful automatic technique that is derived from sequential injection analysis. In LIS, a computer-controlled syringe pump is employed, and its syringe barrel serves as a mixing, reaction, and/or extraction chamber. Until now, the LIS concept has been efficiently employed for the automation of solid-phase microextraction and liquid-phase microextraction protocols as a front-end to a plethora of chromatographic and spectrometric techniques. In this work, the applicability of LIS systems was examined using the Blue Applicability Grade Index (BAGI), a recently introduced metric tool that is used to examine the applicability of an analytical method. For this purpose, the sample preparation procedure and the instrumental method are thoroughly evaluated. The attained BAGI scores ranged between 60.0 and 77.5 for all the examined methods, while the average score was 71.3. As derived from the BAGI evaluation, good practicality can be attributed to the reviewed systems and protocols.

  • Landscape, EIA and decision-making. A case study of the Vistula Spit Canal, Poland
    • Aleksandra Sas-Bojarska
    • Iwona Orzechowska-Szajda
    • Krystian Puzdrakiewicz
    • Magdalena Kiejzik-Głowińska
    2024 Full text Impact Assessment and Project Appraisal

    Although landscapes are often considered public goods, they frequently receive inadequate attention in Environmental Impact Assessments (EIAs), particularly in Poland. This neglect often leads to visible degradation during investment processes. This article examines the case of the Vistula Spit Canal, currently the largest engineering project under construction in Poland. We analysed whether the conclusions drawn in the EIA report, particularly those concerning landscape changes, influenced the decision to proceed with the construction. Although the EIA report described potential landscape changes as both significant and irreversible, the authorities nonetheless approved the project, citing moderate environmental impacts in other areas. This case underscores the tendency to overlook landscape considerations when greenlighting large-scale investments.

  • Large‐Scale Traveling Ionospheric Disturbances Over the European Sector During the Geomagnetic Storm on March 23–24, 2023: Energy Deposition in the Source Regions and the Propagation Characteristics
    • Grzegorz Nykiel
    • Arthur Amaral Ferreira
    • Florian Günzkofer
    • Pelin Iochem
    • Samira Tasnim
    • Hiroatsu Sato
    2024 Full text JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS

    Multiple Large-Scale Traveling Ionospheric Disturbances (LSTIDs) are observed in the European sector in both day-time and night-time during the magnetic storm on March 23–24, 2023. The Total Electron Content (TEC) observation from a network of GNSS receivers shows the propagation of LSTIDs with amplitudes between around 0.5 and 1 TECU originating from auroral and polar cusp regions down to southern Europe (35°N) with velocities between around 500 and 1,600 [m/s]. We study the energy deposition to the LSTIDs in the source regions and the resulting horizontal propagation over storm-time background density by using continuous measurements of EISCAT incoherent scatter radars in northern Norway and Svalbard that allow for estimating the source energy to the thermosphere-ionosphere system via Joule heating and particle precipitation. Both EISCAT and GNSS TEC data show that the electron density decreased to 50% in the auroral zone after the storm onset. The ionospheric heating caused a nearly 250% increase in the electron temperature above 200 km altitude and the ion temperature above 100 km altitude. We find that Joule Heating acts as a primary energy source for the night-time LSTIDs triggered in the auroral region, while the day-time LSTIDs can be also driven by precipitating particles in the polar cusp. We also find that a significant background density decrease over the whole European sector is caused by this storm for the following day, during which almost no clear LSTIDs are observed.

  • Laser-textured cross-hatched surface topography analysis with evaluation of high-frequency measurement noise
    • Przemysław Podulka
    • Wojciech Macek
    • Ricardo Branco
    • Andrzej Kubit
    2024 Full text MEASUREMENT

    The precision of surface roughness determination using ISO 25178 parameters relies on various factors that directly impact the measurement process. In industry applications, the contactless roughness measurement reduces data collection time. However, it introduces several potential errors, including those stemming from the environment. One of the main types of errors encountered during topography analysis is measurement noise, which arises from different external disturbances. High-frequency noise is particularly studied as a result of vibration. In the present study, the laser-texture cross-hatched surface topographies were analysed using the results obtained from white light interference measurements. Measurement noise was defined based on noisy data, also called noise surface, which is the result of filter decomposition methods. This data separation technique was supported with power spectral analysis, autocorrelation function applications and texture direction characterisation. It was suggested to conduct a comprehensive study of the noisy data to enhance the understanding of texturing direction. Various data filtration techniques were studied, namely robust Gaussian, spline, fast Fourier transform and morphological closing-opening filters. The results of the proposed procedure were validated against variations in the values of ISO 25178 surface texture parameters. Validating the proposed approach, the variations of noise-sensitive surface texture parameters were compared to the variations of the same parameters but received by averaging three repeated measurements, as proposed by international standards. The main advantage of the proposed method against standards procedure was reducing the time of data collection when the measurement must be repeated and averaged. In conclusion, a method for reducing high-frequency measurement noise was introduced through the application of the proposed procedure.

  • Lattice-commensurate skyrmion texture in a centrosymmetric breathing kagome magnet
    • Max Hirschberger
    • Bertalan G. Szigeti
    • Mamoun Hemmida
    • Moritz M. Hirschmann
    • Sebastian Esser
    • Hiroyuki Ohsumi
    • Yoshikazu Tanaka
    • Leonie Spitz
    • Shang Gao
    • Kamil Kolincio
    • Hajime Sagayama
    • Hironori Nakao
    • Yuichi Yamasaki
    • László Forró
    • Hans-Albrecht Krug von Nidda
    • Istvan Kezsmarki
    • Taka-hisa Arima
    • Yoshinori Tokura
    2024 Full text npj Quantum Materials

    Skyrmion lattices (SkL) in centrosymmetric materials typically have a magnetic period on the nanometer-scale, so that the coupling between magnetic superstructures and the underlying crystal lattice cannot be neglected. We reveal the commensurate locking of a SkL to the atomic lattice in Gd3Ru4Al12 via high-resolution resonant elastic x-ray scattering (REXS). Weak easy-plane magnetic anisotropy, demonstrated here by a combination of ferromagnetic resonance and REXS, penalizes placing a skyrmion core on a site of the atomic lattice. Under these conditions, a commensurate SkL, locked to the crystal lattice, is stable at finite temperatures – but gives way to a competing incommensurate ground state upon cooling.Wediscuss the role of Umklapp-terms in theHamiltonian for the formation of this lattice-locked state, its magnetic space group, and the role of slight discommensurations, or (line) defects in the magnetic texture. We also contrast our findings with the case of SkLs in noncentrosymmetric material platforms.

  • LCF behavior of 2024AA under uni- and biaxial loading taking into account creep pre-deformation
    • Adam Tomczyk
    • Andrzej Seweryn
    2024 ENGINEERING FRACTURE MECHANICS

    This study presents the results of experimental low-cycle fatigue (LCF) tests of aluminum 2024 alloy T3511 temper in uni- and biaxial loading states. Tests were carried out on both the as-received material (hardened extruded rods) and material with different pre-deformation histories. These deformations were carried out in the creep process at 200 °C and 300 °C for two different levels of at each temperature. The pre-deformed material’s basic fatigue characteristics were determined and compared with the appropriate characteristics of the as-received material. In-depth macro- and microscopic analysis (SEM) of fracture surfaces was done. The effect of preliminary creep on LCF behavior of investigated alloy was characterized for both uni- and biaxial loading. An increase of fatigue life occurs for large plastic strains in the case of cyclic tension/compression. For in-phase biaxial loading, improvement of life is observed only for material with pre-deformation at 300 °C. Crack initiates in the plane of maximum shear strains for both biaxial loading and pure torsion. For tension/compression – in the plane of maximum principal stress (strain).