@article{WelchGuerra, author = {Welch Guerra, Max}, title = {Fach, Gesellschaft und Wissenschaft. Beitrag zur Debatte „Was ist Stadt? Was ist Kritik?"}, series = {sub\urban. zeitschrift f{\"u}r kritische stadtforschung}, volume = {2022}, journal = {sub\urban. zeitschrift f{\"u}r kritische stadtforschung}, number = {Band 10, Nr. 1}, publisher = {Sub\urban e.V.}, address = {Leipzig}, doi = {10.36900/suburban.v10i1.779}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20220810-46855}, pages = {188 -- 190}, abstract = {Der Aufruf, die Begriffe Stadt und Kritik in das Zentrum einer Debatte zu stellen, bietet die große Chance, uns weit {\"u}ber begriffliche Kl{\"a}rungen unseres gemeinsamen Arbeitsgegenstands hinaus - die ja auch f{\"u}r sich selbst sehr fruchtbar sein k{\"o}nnen - {\"u}ber die Funktion zu verst{\"a}ndigen, die wir in der Gesellschaft aus{\"u}ben, wenn wir r{\"a}umliche Planung praktizieren, erforschen und lehren. Da in der Bundesrepublik nicht nur ein großer Bedarf, sondern auch eine betr{\"a}chtliche Nachfrage nach {\"o}ffentlicher Planung besteht und die planungsbezogenen Wissenschaften sich eines insgesamt stabilen institutionellen Standes erfreuen, laufen wir Gefahr, die gesellschaftspolitische Legitimation von Berufsfeld und Wissenschaft zu vernachl{\"a}ssigen, sie als gegeben zu behandeln. Wir m{\"u}ssen uns ja kaum rechtfertigen.}, subject = {Stadt}, language = {de} } @article{BecherVoelkerRodehorstetal., author = {Becher, Lia and V{\"o}lker, Conrad and Rodehorst, Volker and Kuhne, Michael}, title = {Background-oriented schlieren technique for two-dimensional visualization of convective indoor air flows}, series = {Optics and Lasers in Engineering}, volume = {2020}, journal = {Optics and Lasers in Engineering}, number = {Volume 134, article 106282}, doi = {https://doi.org/10.1016/j.optlaseng.2020.106282}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20220810-46972}, pages = {9}, abstract = {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.}, subject = {Raumklima}, language = {en} } @article{Hanna, author = {Hanna, John}, title = {Computational Modelling for the Effects of Capsular Clustering on Fracture of Encapsulation-Based Self-Healing Concrete Using XFEM and Cohesive Surface Technique}, series = {Applied Sciences}, volume = {2022}, journal = {Applied Sciences}, number = {Volume 12, issue 10, article 5112}, publisher = {MDPI}, address = {Basel}, doi = {10.3390/app12105112}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20220721-46717}, pages = {1 -- 17}, abstract = {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.}, subject = {Beton}, language = {en} } @article{GuerlebeckLegatiukWebber, author = {G{\"u}rlebeck, Klaus and Legatiuk, Dmitrii and Webber, Kemmar}, title = {Operator Calculus Approach to Comparison of Elasticity Models for Modelling of Masonry Structures}, series = {Mathematics}, volume = {2022}, journal = {Mathematics}, number = {Volume 10, issue 10, article 1670}, publisher = {MDPI}, address = {Basel}, doi = {10.3390/math10101670}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20220721-46726}, pages = {1 -- 22}, abstract = {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.}, subject = {Mauerwerk}, language = {en} } @article{SoebkeLueck, author = {S{\"o}bke, Heinrich and L{\"u}ck, Andrea}, title = {Framing Algorithm-Driven Development of Sets of Objectives Using Elementary Interactions}, series = {Applied System Innovation}, volume = {2022}, journal = {Applied System Innovation}, number = {Volume 5, issue 3, article 49}, publisher = {MDPI}, address = {Basel}, doi = {10.3390/asi5030049}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20220713-46624}, pages = {1 -- 20}, abstract = {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.}, subject = {Multikriteria-Entscheidung}, language = {en} } @article{DokhanchiArnoldVogeletal.2020, author = {Dokhanchi, Najmeh Sadat and Arnold, J{\"o}rg and Vogel, Albert and V{\"o}lker, Conrad}, title = {Measurement of indoor air temperature distribution using acoustic travel-time tomography: Optimization of transducers location and sound-ray coverage of the room}, series = {Measurement}, volume = {2020}, journal = {Measurement}, number = {Volume 164, article 107934}, publisher = {Elsevier}, address = {Amsterdam}, doi = {10.1016/j.measurement.2020.107934}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20220524-46473}, year = {2020}, abstract = {Acoustic travel-time TOMography (ATOM) allows the measurement and reconstruction of air temperature distributions. Due to limiting factors, such as the challenge of travel-time estimation of the early reflections in the room impulse response, which heavily depends on the position of transducers inside the measurement area, ATOM is applied mainly outdoors. To apply ATOM in buildings, this paper presents a numerical solution to optimize the positions of transducers. This optimization avoids reflection overlaps, leading to distinguishable travel-times in the impulse response reflectogram. To increase the accuracy of the measured temperature within tomographic voxels, an additional function is employed to the proposed numerical method to minimize the number of sound-path-free voxels, ensuring the best sound-ray coverage of the room. Subsequently, an experimental set-up has been performed to verify the proposed numerical method. The results indicate the positive impact of the optimal positions of transducers on the distribution of ATOM-temperatures.}, subject = {Bauphysik}, language = {en} } @article{SoebkeLueck, author = {S{\"o}bke, Heinrich and L{\"u}ck, Andrea}, title = {Framing Algorithm-Driven Development of Sets of Objectives Using Elementary Interactions}, series = {Applied System Innovation}, volume = {2022}, journal = {Applied System Innovation}, number = {Volume 5, issue 49, article 49}, publisher = {MDPI}, address = {Basel}, doi = {10.3390/asi503004}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20220524-46469}, pages = {1 -- 21}, abstract = {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.}, subject = {Operations Research}, language = {en} } @article{TarabenMorgenthal, author = {Taraben, Jakob and Morgenthal, Guido}, title = {Integration and Comparison Methods for Multitemporal Image-Based 2D Annotations in Linked 3D Building Documentation}, series = {Remote Sensing}, volume = {2022}, journal = {Remote Sensing}, number = {Volume 14, issue 9, article 2286}, publisher = {MDPI}, address = {Basel}, doi = {10.3390/rs14092286}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20220513-46488}, pages = {1 -- 20}, abstract = {Data acquisition systems and methods to capture high-resolution images or reconstruct 3D point clouds of existing structures are an effective way to document their as-is condition. These methods enable a detailed analysis of building surfaces, providing precise 3D representations. However, for the condition assessment and documentation, damages are mainly annotated in 2D representations, such as images, orthophotos, or technical drawings, which do not allow for the application of a 3D workflow or automated comparisons of multitemporal datasets. In the available software for building heritage data management and analysis, a wide range of annotation and evaluation functions are available, but they also lack integrated post-processing methods and systematic workflows. The article presents novel methods developed to facilitate such automated 3D workflows and validates them on a small historic church building in Thuringia, Germany. Post-processing steps using photogrammetric 3D reconstruction data along with imagery were implemented, which show the possibilities of integrating 2D annotations into 3D documentations. Further, the application of voxel-based methods on the dataset enables the evaluation of geometrical changes of multitemporal annotations in different states and the assignment to elements of scans or building models. The proposed workflow also highlights the potential of these methods for condition assessment and planning of restoration work, as well as the possibility to represent the analysis results in standardised building model formats.}, subject = {Bauwesen}, language = {en} } @article{AlsaadHartmannHilbeletal., author = {Alsaad, Hayder and Hartmann, Maria and Hilbel, Rebecca and V{\"o}lker, Conrad}, title = {ENVI-met validation data accompanied with simulation data of the impact of facade greening on the urban microclimate}, series = {Data in Brief}, volume = {2022}, journal = {Data in Brief}, number = {Volume 42, article 108200}, publisher = {Elsevier}, address = {Amsterdam}, doi = {10.1016/j.dib.2022.108200}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20220511-46455}, pages = {1 -- 13}, abstract = {This dataset consists mainly of two subsets. The first subset includes measurements and simulation data conducted to validate the simulation tool ENVI-met. The measurements were conducted at the campus of the Bauhaus-University Weimar in Weimar, Germany and consisted of recording exterior air temperature, globe temperature, relative humidity, and wind velocity at 1.5 m at four points on four different days. After the measurements, the geometry of the campus was modelled and meshed; the simulations were conducted using the weather data of the measurements days with the aim of investigating the accuracy of the model. The second data subset consists of ENVI-met simulation data of the potential of facade greening in improving the outdoor environment and the indoor air temperature during heatwaves in Central European cities. The data consist of the boundary conditions and the simulation output of two simulation models: with and without facade greening. The geometry of the models corresponded to a residential buildings district in Stuttgart, Germany. The simulation output consisted of exterior air temperature, mean radiant temperature, relative humidity, and wind velocity at 12 different probe points in the model in addition to the indoor air temperature of an exemplary building. The dataset presents both vertical profiles of the probed parameters as well as the time series output of the five-day simulation duration. Both data subsets correspond to the investigations presented in the co-submitted article [1].}, subject = {Messung}, language = {en} } @article{TeitelbaumAlsaadAvivetal., author = {Teitelbaum, Eric and Alsaad, Hayder and Aviv, Dorit and Kim, Alexander and V{\"o}lker, Conrad and Meggers, Forrest and Pantelic, Jovan}, title = {Addressing a systematic error correcting for free and mixed convection when measuring mean radiant temperature with globe thermometers}, series = {Scientific reports}, volume = {2022}, journal = {Scientific reports}, number = {Volume 12, article 6473}, publisher = {Springer Nature}, address = {London}, doi = {10.1038/s41598-022-10172-5}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20220509-46363}, pages = {18}, abstract = {It is widely accepted that most people spend the majority of their lives indoors. Most individuals do not realize that while indoors, roughly half of heat exchange affecting their thermal comfort is in the form of thermal infrared radiation. We show that while researchers have been aware of its thermal comfort significance over the past century, systemic error has crept into the most common evaluation techniques, preventing adequate characterization of the radiant environment. Measuring and characterizing radiant heat transfer is a critical component of both building energy efficiency and occupant thermal comfort and productivity. Globe thermometers are typically used to measure mean radiant temperature (MRT), a commonly used metric for accounting for the radiant effects of an environment at a point in space. In this paper we extend previous field work to a controlled laboratory setting to (1) rigorously demonstrate that existing correction factors used in the American Society of Heating Ventilation and Air-conditioning Engineers (ASHRAE) Standard 55 or ISO7726 for using globe thermometers to quantify MRT are not sufficient; (2) develop a correction to improve the use of globe thermometers to address problems in the current standards; and (3) show that mean radiant temperature measured with ping-pong ball-sized globe thermometers is not reliable due to a stochastic convective bias. We also provide an analysis of the maximum precision of globe sensors themselves, a piece missing from the domain in contemporary literature.}, subject = {Strahlungstemperatur}, language = {en} }