TY - JOUR A1 - Buschow, Christopher A1 - Wellbrock, Christian-Mathias T1 - “Spotify for News”? User Perception of Subscription-Based Content Platforms for News Media JF - Journalism and Media N2 - Subscription-based news platforms (such as “Apple News+” or “Readly”) that bundle content from different publishers into one comprehensive package and offer it to media users at a fixed monthly rate are a new way of accessing and consuming digital journalism. These services have received little attention in journalism studies, although they differ greatly from traditional media products and distribution channels. This article empirically investigates the perception of journalism platforms based on eight qualitative focus group discussions with 55 German news consumers. Results show that the central characteristics these platforms should fulfill in order to attract users are strikingly similar to the characteristics of media platforms from the music and video industries, in particular regarding price points, contract features, and modes of usage. Against this background, the potential and perspectives of a subscription-based news platform for journalism’s societal role are discussed. KW - Journalistik KW - Journalismus KW - Nachrichtensendung KW - Online-Medien KW - audience studies KW - journalism products KW - content platforms Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:gbv:wim2-20230124-48740 UR - https://www.mdpi.com/2673-5172/4/1/1 VL - 2022 IS - 2023, 4 SP - 1 EP - 15 PB - MDPI CY - Basel ER - TY - JOUR A1 - Alalade, Muyiwa A1 - Reichert, Ina A1 - Köhn, Daniel A1 - Wuttke, Frank A1 - Lahmer, Tom ED - Qu, Chunxu ED - Gao, Chunxu ED - Zhang, Rui ED - Jia, Ziguang ED - Li, Jiaxiang T1 - A Cyclic Multi-Stage Implementation of the Full-Waveform Inversion for the Identification of Anomalies in Dams JF - Infrastructures N2 - For the safe and efficient operation of dams, frequent monitoring and maintenance are required. These are usually expensive, time consuming, and cumbersome. To alleviate these issues, we propose applying a wave-based scheme for the location and quantification of damages in dams. To obtain high-resolution “interpretable” images of the damaged regions, we drew inspiration from non-linear full-multigrid methods for inverse problems and applied a new cyclic multi-stage full-waveform inversion (FWI) scheme. Our approach is less susceptible to the stability issues faced by the standard FWI scheme when dealing with ill-posed problems. In this paper, we first selected an optimal acquisition setup and then applied synthetic data to demonstrate the capability of our approach in identifying a series of anomalies in dams by a mixture of reflection and transmission tomography. The results had sufficient robustness, showing the prospects of application in the field of non-destructive testing of dams. KW - Damm KW - Defekt KW - inverse analysis KW - damage identification KW - full-waveform inversion KW - dams KW - wave propagation KW - OA-Publikationsfonds2022 Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:gbv:wim2-20221201-48396 UR - https://www.mdpi.com/2412-3811/7/12/161 VL - 2022 IS - Volume 7, issue 12, article 161 PB - MDPI CY - Basel ER - TY - JOUR A1 - Arnold, Robert A1 - Kraus, Matthias ED - Pham, Duc T1 - On the nonstationary identification of climate-influenced loads for the semi-probabilistic approach using measured and projected data JF - Cogent Engineering N2 - A safe and economic structural design based on the semi-probabilistic concept requires statistically representative safety elements, such as characteristic values, design values, and partial safety factors. Regarding climate loads, the safety levels of current design codes strongly reflect experiences based on former measurements and investigations assuming stationary conditions, i.e. involving constant frequencies and intensities. However, due to climate change, occurrence of corresponding extreme weather events is expected to alter in the future influencing the reliability and safety of structures and their components. Based on established approaches, a systematically refined data-driven methodology for the determination of design parameters considering nonstationarity as well as standardized targets of structural reliability or safety, respectively, is therefore proposed. The presented procedure picks up fundamentals of European standardization and extends them with respect to nonstationarity by applying a shifting time window method. Taking projected snow loads into account, the application of the method is exemplarily demonstrated and various influencing parameters are discussed. KW - Reliabilität KW - Extreme value distribution KW - climate loads KW - nonstationarity KW - semi-probabilistic concept KW - First Order Reliability Method KW - OA-Publikationsfonds2022 Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:gbv:wim2-20221117-47363 UR - https://doi.org/10.1080/23311916.2022.2143061 VL - 2022 IS - Volume 9, issue 1, article 2143061 SP - 1 EP - 26 PB - Taylor & Francis CY - London ER - TY - JOUR A1 - Lutolli, Blerim T1 - A Review of Domed Cities and Architecture: Past, Present and Future JF - Future cities and environment N2 - The goal of architecture is changing in response to the expanding role of cities, rapid urbanization, and transformation under changing economic, environmental, social, and demographic factors. As cities increased in the early modern era, overcrowding, urbanization, and pollution conditions led reformers to consider the future shape of the cities. One of the most critical topics in contemporary architecture is the subject of the future concepts of living. In most cases, domed cities, as a future concept of living, are rarely considered, and they are used chiefly as “utopian” visions in the discourse of future ways of living. This paper highlights the reviews of domed cities to deepen the understanding of the idea in practice, like its approach in terms of architecture. The main aim of this paper is to provide a broad overview for domed cities in the face of pollution as one of the main concerns in many European cities. As a result, the significance of the reviews of the existing projects is focused on their conceptual quality. This review will pave the way for further studies in terms of future developments in the realm of domed cities. In this paper, the city of Celje, one of the most polluted cities in Slovenia, is taken as a case study for considering the concept of Dome incorporated due to the lack of accessible literature on the topic. This review’s primary contribution is to allow architects to explore a broad spectrum of innovation by comparing today’s achievable statuses against the possibilities generated by domed cities. As a result of this study, the concept of living under the Dome remains to be developed in theory and practice. The current challenging climatic situation will accelerate the evolution of these concepts, resulting in the formation of new typologies, which are a requirement for humanity. KW - Architektur KW - Wohnform KW - Umweltverschutzung KW - Domed Cities KW - Architecture KW - Concept of Living KW - Architecture Pollution KW - Kuppelstadt KW - OA-Publikationsfonds2022 Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:gbv:wim2-20221103-47335 UR - https://futurecitiesandenvironment.com/articles/10.5334/fce.154/ VL - 2022 IS - Volume 8, issue 1 SP - 1 EP - 9 PB - Ubiquity Press Limited CY - London ER - TY - JOUR A1 - Chowdhury, Sharmistha A1 - Kraus, Matthias T1 - Design-related reassessment of structures integrating Bayesian updating of model safety factors JF - Results in Engineering N2 - In the semi-probabilistic approach of structural design, the partial safety factors are defined by considering some degree of uncertainties to actions and resistance, associated with the parameters’ stochastic nature. However, uncertainties for individual structures can be better examined by incorporating measurement data provided by sensors from an installed health monitoring scheme. In this context, the current study proposes an approach to revise the partial safety factor for existing structures on the action side, γE by integrating Bayesian model updating. A simple numerical example of a beam-like structure with artificially generated measurement data is used such that the influence of different sensor setups and data uncertainties on revising the safety factors can be investigated. It is revealed that the health monitoring system can reassess the current capacity reserve of the structure by updating the design safety factors, resulting in a better life cycle assessment of structures. The outcome is furthermore verified by analysing a real life small railway steel bridge ensuring the applicability of the proposed method to practical applications. KW - Lebenszyklus KW - Sicherheitsfaktor KW - Structural health monitoring KW - Safety factor KW - Life cycle assessment KW - Uncertainty KW - Bayesian parameter update KW - Ungewissheit KW - Umweltbilanz KW - OA-Publikationsfonds2022 Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:gbv:wim2-20221028-47294 UR - https://www.sciencedirect.com/science/article/pii/S2590123022002304?via%3Dihub VL - 2022 IS - Volume 16, article 100560 SP - 1 EP - 1 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Chowdhury, Sharmistha A1 - Zabel, Volkmar T1 - Influence of loading sequence on wind induced fatigue assessment of bolts in TV-tower connection block JF - Results in Engineering N2 - Bolted connections are widely employed in structures like transmission poles, wind turbines, and television (TV) towers. The behaviour of bolted connections is often complex and plays a significant role in the overall dynamic characteristics of the structure. The goal of this work is to conduct a fatigue lifecycle assessment of such a bolted connection block of a 193 m tall TV tower, for which 205 days of real measurement data have been obtained from the installed monitoring devices. Based on the recorded data, the best-fit stochastic wind distribution for 50 years, the decisive wind action, and the locations to carry out the fatigue analysis have been decided. A 3D beam model of the entire tower is developed to extract the nodal forces corresponding to the connection block location under various mean wind speeds, which is later coupled with a detailed complex finite element model of the connection block, with over three million degrees of freedom, for acquiring stress histories on some pre-selected bolts. The random stress histories are analysed using the rainflow counting algorithm (RCA) and the damage is estimated using Palmgren-Miner's damage accumulation law. A modification is proposed to integrate the loading sequence effect into the RCA, which otherwise is ignored, and the differences between the two RCAs are investigated in terms of the accumulated damage. KW - Schadensakkumulation KW - Lebenszyklus KW - Fatigue life KW - Damage accumulation KW - Wind load KW - Rainflow counting algorithm KW - Loading sequence KW - Windlast KW - OA-Publikationsfonds2022 Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:gbv:wim2-20221028-47303 UR - https://www.sciencedirect.com/science/article/pii/S2590123022002730?via%3Dihub VL - 2022 IS - Volume 16, article 100603 SP - 1 EP - 18 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Harirchian, Ehsan A1 - Isik, Ercan T1 - A Comparative Probabilistic Seismic Hazard Analysis for Eastern Turkey (Bitlis) Based on Updated Hazard Map and Its Effect on Regular RC Structures JF - Buildings N2 - Determining the earthquake hazard of any settlement is one of the primary studies for reducing earthquake damage. Therefore, earthquake hazard maps used for this purpose must be renewed over time. Turkey Earthquake Hazard Map has been used instead of Turkey Earthquake Zones Map since 2019. A probabilistic seismic hazard was performed by using these last two maps and different attenuation relationships for Bitlis Province (Eastern Turkey) were located in the Lake Van Basin, which has a high seismic risk. The earthquake parameters were determined by considering all districts and neighborhoods in the province. Probabilistic seismic hazard analyses were carried out for these settlements using seismic sources and four different attenuation relationships. The obtained values are compared with the design spectrum stated in the last two earthquake maps. Significant differences exist between the design spectrum obtained according to the different exceedance probabilities. In this study, adaptive pushover analyses of sample-reinforced concrete buildings were performed using the design ground motion level. Structural analyses were carried out using three different design spectra, as given in the last two seismic design codes and the mean spectrum obtained from attenuation relationships. Different design spectra significantly change the target displacements predicted for the performance levels of the buildings. KW - Erbeben KW - Schwellenwert KW - Seismic risk KW - Adaptive Pushover KW - Design Spectra KW - OA-Publikationsfonds2022 Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:gbv:wim2-20221028-47283 UR - https://www.mdpi.com/2075-5309/12/10/1573 VL - 2022 IS - Volume 12, issue 10, article 1573 SP - 1 EP - 19 PB - MDPI CY - Basel ER - TY - JOUR A1 - Maiwald, Holger A1 - Schwarz, Jochen A1 - Kaufmann, Christian A1 - Langhammer, Tobias A1 - Golz, Sebastian A1 - Wehner, Theresa T1 - Innovative Vulnerability and Risk Assessment of Urban Areas against Flood Events: Prognosis of Structural Damage with a New Approach Considering Flow Velocity JF - Water N2 - The floods in 2002 and 2013, as well as the recent flood of 2021, caused billions Euros worth of property damage in Germany. The aim of the project Innovative Vulnerability and Risk Assessment of Urban Areas against Flood Events (INNOVARU) involved the development of a practicable flood damage model that enables realistic damage statements for the residential building stock. In addition to the determination of local flood risks, it also takes into account the vulnerability of individual buildings and allows for the prognosis of structural damage. In this paper, we discuss an improved method for the prognosis of structural damage due to flood impact. Detailed correlations between inundation level and flow velocities depending on the vulnerability of the building types, as well as the number of storeys, are considered. Because reliable damage data from events with high flow velocities were not available, an innovative approach was adopted to cover a wide range of flow velocities. The proposed approach combines comprehensive damage data collected after the 2002 flood in Germany with damage data of the 2011 Tohoku earthquake tsunami in Japan. The application of the developed methods enables a reliable reinterpretation of the structural damage caused by the August flood of 2002 in six study areas in the Free State of Saxony. KW - Bauschaden KW - Hochwasser KW - Hochwasserschadensmodell KW - Strukturschaden KW - Strömungsgeschwindigkeit KW - Schadensprognose KW - OA-Publikationsfonds2022 Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:gbv:wim2-20221012-47254 UR - https://www.mdpi.com/2073-4441/14/18/2793 VL - 2022 IS - Volume 14, issue 18, article 2793 SP - 1 EP - 28 PB - MDPI CY - Basel ER - TY - JOUR A1 - Mehling, Simon A1 - Schnabel, Tobias A1 - Londong, Jörg T1 - Investigation on Energetic Efficiency of Reactor Systems for Oxidation of Micro-Pollutants by Immobilized Active Titanium Dioxide Photocatalysis JF - Water N2 - In this work, the degradation performance for the photocatalytic oxidation of eight micropollutants (amisulpride, benzotriazole, candesartan, carbamazepine, diclofenac, gabapentin, methlybenzotriazole, and metoprolol) within real secondary effluent was investigated using three different reactor designs. For all reactor types, the influence of irradiation power on its reaction rate and energetic efficiency was investigated. Flat cell and batch reactor showed almost similar substance specific degradation behavior. Within the immersion rotary body reactor, benzotriazole and methylbenzotriazole showed a significantly lower degradation affinity. The flat cell reactor achieved the highest mean degradation rate, with half time values ranging from 5 to 64 min with a mean of 18 min, due to its high catalysts surface to hydraulic volume ratio. The EE/O values were calculated for all micro-pollutants as well as the mean degradation rate constant of each experimental step. The lowest substance specific energy per order (EE/O) values of 5 kWh/m3 were measured for benzotriazole within the batch reactor. The batch reactor also reached the lowest mean values (11.8–15.9 kWh/m3) followed by the flat cell reactor (21.0–37.0 kWh/m3) and immersion rotary body reactor (23.9–41.0 kWh/m3). Catalyst arrangement and irradiation power were identified as major influences on the energetic performance of the reactors. Low radiation intensities as well as the use of submerged catalyst arrangement allowed a reduction in energy demand by a factor of 3–4. A treatment according to existing treatment goals of wastewater treatment plants (80% total degradation) was achieved using the batch reactor with a calculated energy demand of 7000 Wh/m3. KW - Fotokatalyse KW - Abwasserreinigung KW - photocatalysis KW - micro-pollutant treatment KW - titanium dioxid KW - reactor design KW - energy per order KW - OA-Publikationsfonds2022 Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:gbv:wim2-20220912-47130 UR - https://www.mdpi.com/2073-4441/14/17/2681 VL - 2022 IS - Volume 14, issue 7, article 2681 SP - 1 EP - 15 PB - MDPI CY - Basel ER - TY - JOUR A1 - Al-Yasiri, Zainab Riyadh Shaker A1 - Mutashar, Hayder Majid A1 - Gürlebeck, Klaus A1 - Lahmer, Tom ED - Shafiullah, GM T1 - Damage Sensitive Signals for the Assessment of the Conditions of Wind Turbine Rotor Blades Using Electromagnetic Waves JF - Infrastructures N2 - One of the most important renewable energy technologies used nowadays are wind power turbines. In this paper, we are interested in identifying the operating status of wind turbines, especially rotor blades, by means of multiphysical models. It is a state-of-the-art technology to test mechanical structures with ultrasonic-based methods. However, due to the density and the required high resolution, the testing is performed with high-frequency waves, which cannot penetrate the structure in depth. Therefore, there is a need to adopt techniques in the fields of multiphysical model-based inversion schemes or data-driven structural health monitoring. Before investing effort in the development of such approaches, further insights and approaches are necessary to make the techniques applicable to structures such as wind power plants (blades). Among the expected developments, further accelerations of the so-called “forward codes” for a more efficient implementation of the wave equation could be envisaged. Here, we employ electromagnetic waves for the early detection of cracks. Because in many practical situations, it is not possible to apply techniques from tomography (characterized by multiple sources and sensor pairs), we focus here on the question of whether the existence of cracks can be determined by using only one source for the sent waves. KW - Windkraftwerk KW - Rotorblatt KW - Elektrostatische Welle KW - MATLAB KW - wind turbine rotor blades KW - electromagnetic waves KW - crack detection KW - Empire XPU 8.01 KW - Matlab KW - OA-Publikationsfonds2022 Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:gbv:wim2-20220831-47093 UR - https://www.mdpi.com/2412-3811/7/8/104 VL - 2022 IS - Volume 7, Issue 8 (August 2022), article 104 PB - MDPI CY - Basel ER - TY - JOUR A1 - Artus, Mathias A1 - Koch, Christian T1 - Object-Oriented Damage Information Modeling Concepts and Implementation for Bridge Inspection JF - Journal of Computing in Civil Engineering N2 - Bridges are designed to last for more than 50 years and consume up to 50% of their life-cycle costs during their operation phase. Several inspections and assessment actions are executed during this period. Bridge and damage information must be gathered, digitized, and exchanged between different stakeholders. Currently, the inspection and assessment practices rely on paper-based data collection and exchange, which is time-consuming and error-prone, and leads to loss of information. Storing and exchanging damage and building information in a digital format may lower costs and errors during inspection and assessment and support future needs, for example, immediate simulations regarding performance assessment, automated maintenance planning, and mixed reality inspections. This study focused on the concept for modeling damage information to support bridge reviews and structural analysis. Starting from the definition of multiple use cases and related requirements, the data model for damage information is defined independently from the subsequent implementation. In the next step, the implementation via an established standard is explained. Functional tests aim to identify problems in the concept and implementation. To show the capability of the final model, two example use cases are illustrated: the inspection review of the entire bridge and a finite-element analysis of a single component. Main results are the definition of necessary damage data, an object-oriented damage model, which supports multiple use cases, and the implementation of the model in a standard. Furthermore, the tests have shown that the standard is suitable to deliver damage information; however, several software programs lack proper implementation of the standard. KW - Building Information Modeling KW - Brücke KW - Inspektion KW - Produktdaten KW - Objektorientierung KW - Building Information Modeling KW - Bridge KW - Inspection KW - Damage Information Modeling KW - Damage Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:gbv:wim2-20220826-47087 UR - https://ascelibrary.org/doi/10.1061/%28ASCE%29CP.1943-5487.0001030 VL - 2022 IS - Volume 36, issue 6 SP - 1 EP - 21 ER - TY - JOUR A1 - Patzelt, Max A1 - Erfurt, Doreen A1 - Ludwig, Horst-Michael T1 - Quantification of cracks in concrete thin sections considering current methods of image analysis JF - Journal of Microscopy N2 - Image analysis is used in this work to quantify cracks in concrete thin sections via modern image processing. Thin sections were impregnated with a yellow epoxy resin, to increase the contrast between voids and other phases of the concrete. By the means of different steps of pre-processing, machine learning and python scripts, cracks can be quantified in an area of up to 40 cm2. As a result, the crack area, lengths and widths were estimated automatically within a single workflow. Crack patterns caused by freeze-thaw damages were investigated. To compare the inner degradation of the investigated thin sections, the crack density was used. Cracks in the thin sections were measured manually in two different ways for validation of the automatic determined results. On the one hand, the presented work shows that the width of cracks can be determined pixelwise, thus providing the plot of a width distribution. On the other hand, the automatically measured crack length differs in comparison to the manually measured ones. KW - Beton KW - Rissbildung KW - Bildanalyse KW - Maschinelles Lernen KW - Mikroskopie KW - concrete KW - crack KW - degradation KW - transmitted light microscopy Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:gbv:wim2-20220811-46754 UR - https://onlinelibrary.wiley.com/doi/full/10.1111/jmi.13091 VL - 2022 IS - Volume 286, Issue 2 SP - 154 EP - 159 ER - TY - JOUR A1 - Guo, Hongwei A1 - Zhuang, Xiaoying A1 - Chen, Pengwan A1 - Alajlan, Naif A1 - Rabczuk, Timon T1 - Analysis of three-dimensional potential problems in non-homogeneous media with physics-informed deep collocation method using material transfer learning and sensitivity analysis JF - Engineering with Computers N2 - In this work, we present a deep collocation method (DCM) for three-dimensional potential problems in non-homogeneous media. This approach utilizes a physics-informed neural network with material transfer learning reducing the solution of the non-homogeneous partial differential equations to an optimization problem. We tested different configurations of the physics-informed neural network including smooth activation functions, sampling methods for collocation points generation and combined optimizers. A material transfer learning technique is utilized for non-homogeneous media with different material gradations and parameters, which enhance the generality and robustness of the proposed method. In order to identify the most influential parameters of the network configuration, we carried out a global sensitivity analysis. Finally, we provide a convergence proof of our DCM. The approach is validated through several benchmark problems, also testing different material variations. KW - Deep learning KW - Kollokationsmethode KW - Collocation method KW - Potential problem KW - Activation function KW - Transfer learning Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:gbv:wim2-20220811-46764 UR - https://link.springer.com/article/10.1007/s00366-022-01633-6 VL - 2022 SP - 1 EP - 22 ER - TY - JOUR A1 - Chakraborty, Ayan A1 - Anitescu, Cosmin A1 - Zhuang, Xiaoying A1 - Rabczuk, Timon T1 - Domain adaptation based transfer learning approach for solving PDEs on complex geometries JF - Engineering with Computers N2 - In machine learning, if the training data is independently and identically distributed as the test data then a trained model can make an accurate predictions for new samples of data. Conventional machine learning has a strong dependence on massive amounts of training data which are domain specific to understand their latent patterns. In contrast, Domain adaptation and Transfer learning methods are sub-fields within machine learning that are concerned with solving the inescapable problem of insufficient training data by relaxing the domain dependence hypothesis. In this contribution, this issue has been addressed and by making a novel combination of both the methods we develop a computationally efficient and practical algorithm to solve boundary value problems based on nonlinear partial differential equations. We adopt a meshfree analysis framework to integrate the prevailing geometric modelling techniques based on NURBS and present an enhanced deep collocation approach that also plays an important role in the accuracy of solutions. We start with a brief introduction on how these methods expand upon this framework. We observe an excellent agreement between these methods and have shown that how fine-tuning a pre-trained network to a specialized domain may lead to an outstanding performance compare to the existing ones. As proof of concept, we illustrate the performance of our proposed model on several benchmark problems. KW - Maschinelles Lernen KW - NURBS KW - Transfer learning KW - Domain Adaptation KW - NURBS geometry KW - Navier–Stokes equations Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:gbv:wim2-20220811-46776 UR - https://link.springer.com/article/10.1007/s00366-022-01661-2 VL - 2022 SP - 1 EP - 20 ER - TY - JOUR A1 - Roskamm, Nikolai A1 - Vollmer, Lisa T1 - Was ist Stadt? Was ist Kritik? Einführung in die Debatte zum Jubiläumsheft von sub\urban JF - sub\urban. zeitschrift für kritische stadtforschung N2 - Im Heft zum zehnjährigen Jubiläum von sub\urban mit dem Themenschwerpunkt „sub\x: Verortungen, Entortungen" veröffentlichen wir eine Debatte, die von den bisherigen in unserer Zeitschrift in dieser Rubrik geführten textlichen Diskussionen abweicht. Im Vorfeld der Planungen für unsere Jubiläumsausgabe haben wir die aktuellen Mitglieder unseres wissenschaftlichen Beirats darum gebeten, zwei grundlegende Fragen von kritischer Stadtforschung in kurzen Beiträgen zu diskutieren: Was ist Stadt? Was ist Kritik? KW - Stadt KW - Stadtforschung KW - Kritik KW - Theorie KW - kritische Stadtforschung KW - Debatte KW - Stadtbegriff KW - Kritikbegriff KW - OA-Publikationsfonds2022 Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:gbv:wim2-20220811-46847 UR - https://zeitschrift-suburban.de/sys/index.php/suburban/article/view/798 IS - Band 10, Nr. 1, SP - 127 EP - 130 PB - Sub\urban e.V. CY - Leipzig ER - TY - JOUR A1 - Welch Guerra, Max T1 - Fach, Gesellschaft und Wissenschaft. Beitrag zur Debatte „Was ist Stadt? Was ist Kritik?“ JF - sub\urban. zeitschrift für kritische stadtforschung N2 - Der Aufruf, die Begriffe Stadt und Kritik in das Zentrum einer Debatte zu stellen, bietet die große Chance, uns weit über begriffliche Klärungen unseres gemeinsamen Arbeitsgegenstands hinaus – die ja auch für sich selbst sehr fruchtbar sein können – über die Funktion zu verständigen, die wir in der Gesellschaft ausüben, wenn wir räumliche Planung praktizieren, erforschen und lehren. Da in der Bundesrepublik nicht nur ein großer Bedarf, sondern auch eine beträchtliche Nachfrage nach öffentlicher Planung besteht und die planungsbezogenen Wissenschaften sich eines insgesamt stabilen institutionellen Standes erfreuen, laufen wir Gefahr, die gesellschaftspolitische Legitimation von Berufsfeld und Wissenschaft zu vernachlässigen, sie als gegeben zu behandeln. Wir müssen uns ja kaum rechtfertigen. KW - Stadt KW - Kritik KW - Wissenschaftskritik KW - Kritikbegriff KW - Herrschaftskritik KW - Alltagskritik KW - OA-Publikationsfonds2022 Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:gbv:wim2-20220810-46855 UR - https://zeitschrift-suburban.de/sys/index.php/suburban/article/view/779 VL - 2022 IS - Band 10, Nr. 1 SP - 188 EP - 190 PB - Sub\urban e.V. CY - Leipzig ER - TY - JOUR A1 - Becher, Lia A1 - Völker, Conrad A1 - Rodehorst, Volker A1 - Kuhne, Michael T1 - Background-oriented schlieren technique for two-dimensional visualization of convective indoor air flows JF - Optics and Lasers in Engineering N2 - This article focuses on further developments of the background-oriented schlieren (BOS) technique to visualize convective indoor air flow, which is usually defined by very small density gradients. Since the light rays deflect when passing through fluids with different densities, BOS can detect the resulting refractive index gradients as integration along a line of sight. In this paper, the BOS technique is used to yield a two-dimensional visualization of small density gradients. The novelty of the described method is the implementation of a highly sensitive BOS setup to visualize the ascending thermal plume from a heated thermal manikin with temperature differences of minimum 1 K. To guarantee steady boundary conditions, the thermal manikin was seated in a climate laboratory. For the experimental investigations, a high-resolution DLSR camera was used capturing a large field of view with sufficient detail accuracy. Several parameters such as various backgrounds, focal lengths, room air temperatures, and distances between the object of investigation, camera, and structured background were tested to find the most suitable parameters to visualize convective indoor air flow. Besides these measurements, this paper presents the analyzing method using cross-correlation algorithms and finally the results of visualizing the convective indoor air flow with BOS. The highly sensitive BOS setup presented in this article complements the commonly used invasive methods that highly influence weak air flows. KW - Raumklima KW - Raumluftströmungen KW - Flow visualization KW - Convective indoor air flow KW - Background-oriented schlieren KW - Human thermal plume KW - Cross-correlation Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:gbv:wim2-20220810-46972 N1 - This article is published by Elsevier in Optics and Lasers in Engineering 134 (2020) 106282 and may be found at https://doi.org/10.1016/j.optlaseng.2020.106282 Copyright © 2020 Elsevier Ltd. All rights reserved. This article may be downloaded for personal use only. Any other use requires prior permission of the authors and Elsevier Ltd. VL - 2020 IS - Volume 134, article 106282 ER - TY - JOUR A1 - Hanna, John T1 - Computational Modelling for the Effects of Capsular Clustering on Fracture of Encapsulation-Based Self-Healing Concrete Using XFEM and Cohesive Surface Technique JF - Applied Sciences N2 - The fracture of microcapsules is an important issue to release the healing agent for healing the cracks in encapsulation-based self-healing concrete. The capsular clustering generated from the concrete mixing process is considered one of the critical factors in the fracture mechanism. Since there is a lack of studies in the literature regarding this issue, the design of self-healing concrete cannot be made without an appropriate modelling strategy. In this paper, the effects of microcapsule size and clustering on the fractured microcapsules are studied computationally. A simple 2D computational modelling approach is developed based on the eXtended Finite Element Method (XFEM) and cohesive surface technique. The proposed model shows that the microcapsule size and clustering have significant roles in governing the load-carrying capacity and the crack propagation pattern and determines whether the microcapsule will be fractured or debonded from the concrete matrix. The higher the microcapsule circumferential contact length, the higher the load-carrying capacity. When it is lower than 25% of the microcapsule circumference, it will result in a greater possibility for the debonding of the microcapsule from the concrete. The greater the core/shell ratio (smaller shell thickness), the greater the likelihood of microcapsules being fractured. KW - Beton KW - Mikrokapsel KW - Rissausbreitung KW - Tragfähigkeit KW - self-healing concrete KW - microcapsule KW - capsular clustering KW - circumferential contact length KW - OA-Publikationsfonds2022 Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:gbv:wim2-20220721-46717 UR - https://www.mdpi.com/2076-3417/12/10/5112 VL - 2022 IS - Volume 12, issue 10, article 5112 SP - 1 EP - 17 PB - MDPI CY - Basel ER - TY - JOUR A1 - Gürlebeck, Klaus A1 - Legatiuk, Dmitrii A1 - Webber, Kemmar T1 - Operator Calculus Approach to Comparison of Elasticity Models for Modelling of Masonry Structures JF - Mathematics N2 - The solution of any engineering problem starts with a modelling process aimed at formulating a mathematical model, which must describe the problem under consideration with sufficient precision. Because of heterogeneity of modern engineering applications, mathematical modelling scatters nowadays from incredibly precise micro- and even nano-modelling of materials to macro-modelling, which is more appropriate for practical engineering computations. In the field of masonry structures, a macro-model of the material can be constructed based on various elasticity theories, such as classical elasticity, micropolar elasticity and Cosserat elasticity. Evidently, a different macro-behaviour is expected depending on the specific theory used in the background. Although there have been several theoretical studies of different elasticity theories in recent years, there is still a lack of understanding of how modelling assumptions of different elasticity theories influence the modelling results of masonry structures. Therefore, a rigorous approach to comparison of different three-dimensional elasticity models based on quaternionic operator calculus is proposed in this paper. In this way, three elasticity models are described and spatial boundary value problems for these models are discussed. In particular, explicit representation formulae for their solutions are constructed. After that, by using these representation formulae, explicit estimates for the solutions obtained by different elasticity theories are obtained. Finally, several numerical examples are presented, which indicate a practical difference in the solutions. KW - Mauerwerk KW - Elastizitätstheorie KW - Mathematische Modellierung KW - quaternionic analysis KW - mathematical modelling KW - operator calculus KW - model comparison KW - micropolar elasticity KW - OA-Publikationsfonds2022 Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:gbv:wim2-20220721-46726 UR - https://www.mdpi.com/2227-7390/10/10/1670 VL - 2022 IS - Volume 10, issue 10, article 1670 SP - 1 EP - 22 PB - MDPI CY - Basel ER - TY - JOUR A1 - Söbke, Heinrich A1 - Lück, Andrea T1 - Framing Algorithm-Driven Development of Sets of Objectives Using Elementary Interactions JF - Applied System Innovation N2 - Multi-criteria decision analysis (MCDA) is an established methodology to support the decision-making of multi-objective problems. For conducting an MCDA, in most cases, a set of objectives (SOO) is required, which consists of a hierarchical structure comprised of objectives, criteria, and indicators. The development of an SOO is usually based on moderated development processes requiring high organizational and cognitive effort from all stakeholders involved. This article proposes elementary interactions as a key paradigm of an algorithm-driven development process for an SOO that requires little moderation efforts. Elementary interactions are self-contained information requests that may be answered with little cognitive effort. The pairwise comparison of elements in the well-known analytical hierarchical process (AHP) is an example of an elementary interaction. Each elementary interaction in the development process presented contributes to the stepwise development of an SOO. Based on the hypothesis that an SOO may be developed exclusively using elementary interactions (EIs), a concept for a multi-user platform is proposed. Essential components of the platform are a Model Aggregator, an Elementary Interaction Stream Generator, a Participant Manager, and a Discussion Forum. While the latter component serves the professional exchange of the participants, the first three components are intended to be automatable by algorithms. The platform concept proposed has been evaluated partly in an explorative validation study demonstrating the general functionality of the algorithms outlined. In summary, the platform concept suggested demonstrates the potential to ease SOO development processes as the platform concept does not restrict the application domain; it is intended to work with little administration moderation efforts, and it supports the further development of an existing SOO in the event of changes in external conditions. The algorithm-driven development of SOOs proposed in this article may ease the development of MCDA applications and, thus, may have a positive effect on the spread of MCDA applications. KW - Multikriteria-Entscheidung KW - Multikriterielle Entscheidungsanalyse KW - multi-criteria decision analysis; KW - set of objectives KW - crowdsourcing KW - platform KW - elementary interaction KW - OA-Publikationsfonds2022 Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:gbv:wim2-20220713-46624 UR - https://www.mdpi.com/2571-5577/5/3/49 VL - 2022 IS - Volume 5, issue 3, article 49 SP - 1 EP - 20 PB - MDPI CY - Basel ER -