Refine
Document Type
- Conference Proceeding (296)
- Article (238)
- Doctoral Thesis (70)
- Report (14)
- Part of a Book (9)
- Master's Thesis (9)
- Book (7)
- Preprint (4)
- Periodical (2)
- Review (2)
- Study Thesis (2)
- Diploma Thesis (1)
- Habilitation (1)
Institute
- Professur Informatik im Bauwesen (190)
- In Zusammenarbeit mit der Bauhaus-Universität Weimar (116)
- Professur Theorie und Geschichte der modernen Architektur (83)
- Institut für Strukturmechanik (ISM) (50)
- Graduiertenkolleg 1462 (20)
- Professur Bauphysik (14)
- Professur Angewandte Mathematik (9)
- Institut für Europäische Urbanistik (8)
- Professur Computergestütztes kooperatives Arbeiten (8)
- Professur Betriebswirtschaftslehre im Bauwesen (7)
Keywords
- Computerunterstütztes Verfahren (150)
- Architektur <Informatik> (99)
- Angewandte Informatik (91)
- Angewandte Mathematik (86)
- CAD (71)
- Bauhaus-Kolloquium (66)
- Weimar (66)
- Architektur (58)
- Computer Science Models in Engineering; Multiscale and Multiphysical Models; Scientific Computing (41)
- 2003 (30)
Research into bio-based epoxy resins has intensified in recent decades. Here, it is of great importance to use raw materials whose use does not compete with food production. In addition, the performance of the newly developed materials should be comparable to that of conventional products. Possible starting materials are lignin degradation products, such as vanillin and syringaldehyde, for which new synthesis routes to the desired products must be found and their properties determined. In this article, the first synthesis of two amine hardeners, starting with vanillin and syringaldehyde, using the Smiles rearrangement reaction is reported. The amine hardeners were mixed with bisphenol A diglycidyl ether, and the curing was compared to isophorone diamine, 4-4′-diaminodiphenyl sulfone, and 4-Aminonbenzylamine by means of differential scanning calorimetry. It was found that the two amines prepared are cold-curing. As TG-MS studies showed, the thermal stability of at least one of the polymers prepared with the potentially bio-based amines is comparable to that of the polymer prepared with isophorone diamine, and similar degradation products are formed during pyrolysis.
Physical exercise demonstrates a special case of aerosol emission due to its associated elevated breathing rate. This can lead to a faster spread of airborne viruses and respiratory diseases. Therefore, this study investigates cross-infection risk during training. Twelve human subjects exercised on a cycle ergometer under three mask scenarios: no mask, surgical mask, and FFP2 mask. The emitted aerosols were measured in a grey room with a measurement setup equipped with an optical particle sensor. The spread of expired air was qualitatively and quantitatively assessed using schlieren imaging. Moreover, user satisfaction surveys were conducted to evaluate the comfort of wearing face masks during training. The results indicated that both surgical and FFP2 masks significantly reduced particles emission with a reduction efficiency of 87.1% and 91.3% of all particle sizes, respectively. However, compared to surgical masks, FFP2 masks provided a nearly tenfold greater reduction of the particle size range with long residence time in the air (0.3–0.5 μm). Furthermore, the investigated masks reduced exhalation spreading distances to less than 0.15 m and 0.1 m in the case of the surgical mask and FFP2 mask, respectively. User satisfaction solely differed with respect to perceived dyspnea between no mask and FFP2 mask conditions.
This paper addresses the scope for action by municipalities in a climate emergency and places it in the framework of ecomodern (urban) policy. We analyse the way in which two German ‘climate emergency municipalities’ translate conflicts of post-fossil transformation into concrete political and planning strategies. Although more than 2,200 authorities around the world have already declared a climate emergency, research on the impact of these resolutions on the political orientation of municipalities is very limited. Our research focus is on the (potentially agonistic) treatment of conflicts in planning. We argue that in times of a socio-ecological crisis, success in conflict resolution cannot refer to appeasement and depoliticisation. Instead, we propose a framework of five criteria, based on critical theory on ecomodern strategies, planning processes and degrowth. Thus, this practice-related and explorative paper connects empirical insights from the German cities of Constance and Berlin with an innovative normative framework. The findings tell a complex story of an, at least partial, admission of the failure of previous climate mitigation strategies, a lack of social institutions of limits, an instrumental relation to nature and a disregard for social injustices. The paper discusses how municipalities, in the context of ongoing tensions over the post-fossil transformation in Germany, on the one hand hold on to business-as-usual approaches, but on the other hand also set political impulses for change.
The present article aims to provide an overview of the consequences of dynamic soil-structure interaction (SSI) on building structures and the available modelling techniques to resolve SSI problems. The role of SSI has been traditionally considered beneficial to the response of structures. However, contemporary studies and evidence from past earthquakes showed detrimental effects of SSI in certain conditions. An overview of the related investigations and findings is presented and discussed in this article. Additionally, the main approaches to evaluate seismic soil-structure interaction problems with the commonly used modelling techniques and computational methods are highlighted. The strength, limitations, and application cases of each model are also discussed and compared. Moreover, the role of SSI in various design codes and global guidelines is summarized. Finally, the advancements and recent findings on the SSI effects on the seismic response of buildings with different structural systems and foundation types are presented. In addition, with the aim of helping new researchers to improve previous findings, the research gaps and future research tendencies in the SSI field are pointed out.
Audiovisuelles Cut-Up
(2023)
Diese Forschungsarbeit bezeichnet und analysiert ein ästhetisches Phänomen audiovisueller Arbeiten mit sehr schnellen Schnitten. Der Begriff „Audiovisuelles Cut-Up“ wird vorgeschlagen um dieses Phänomen zu bezeichnen. Verschiedenste audiovisuelle Arbeiten aus unterschiedlichen Kontexten werden analysiert, welche das formale Kriterium von extrem kurzen Einstellungen erfüllen – einschließlich der eigenen Forschungsbeiträge des Autors. Die Werkzeuge und Technologien, welche die neuartige Ästhetik ermöglichten werden vorgestellt. Oftmals wurden diese von den Künstlern selbst geschaffen, da fertige Lösungen nicht verfügbar waren. Audiovisuelle Cut-Ups werden nach Kontext und Medium systematisiert und verortet. Es schließen sich Beobachtungen an, in wie fern Audio und Video sich in ihrem Charakter unterscheiden, was die kleinste wahrnehmbare Einheit ist und welche Rolle Latenzen und Antizipation bei der Wahrnehmung von audiovisuellen Medien spielen.
Drei Hauptthesen werden Aufgestellt: 1. Audiovisuelles Cut-Up hat die Kraft winzige, vormals überdeckte Details deutlich zu machen. Damit kann es das Quellmaterial verdichten aber auch den Inhalt manipulieren. 2. Technische Entwicklungen haben das audiovisuelle Cut-Up hervorgerufen. 3. Heute ist die Ästhetik als ein Stilmittel im Werkzeugkasten audiovisueller Gestaltung etabliert.
Antimicrobial resistances (AMR) are ranked among the top ten threats to public health and societal development worldwide. Toilet wastewater contained in domestic wastewater is a significant source of AMR entering the aquatic environment. The current commonly implemented combined sewer systems at times cause overflows during rain events, resulting in the discharge of untreated wastewater into the aquatic environment, thus promoting AMR. In this short research article, we describe an approach to transform combined sewer systems into source separation-modified combined sewer systems that separately treat toilet wastewater. We employ simulations for demonstrating that source separation-modified combined sewer systems reduce the emission of AMR- causing substances by up to 11.5 logarithm levels. Thus, source separation- modified combined sewer systems are amongst the most effective means of combating AMR.
KEYWORDS
The most fundamental understating of hybridization methodology takes the form of stable but dynamic notions, accumulated over time in the memory of individuals. Schematized and abstracted, the hybrids representation needs to be reproduced and reused in order to reconstruct and bring back other memories. Reinvented, or reused hybrids can support getting access to social, traditional, religious understanding of nations. In this manner, they take the form of the messenger / the mediator an innate, equivalent to the use of mental places in the art of memory. We remember mythology in order to remember other things.
From individual memory perspective, or group collective memory, the act of recollection is assumed to be an individual act, biologically based in the brain, but by definition conditioned by social collectives. Following Halbwachs, this thesis does not recognize a dichotomy between individual and collective memory as two different types of remembering. Conversely, the collective is thought of as inherent to individual thought, questioning perspectives that regard individual recollection as isolated from social settings. The individual places himself in relation to the group and makes use of the collective frameworks of thought when he localizes and reconstructs the past, whether in private or in social settings. The frameworks of social relations, of time, and of space are constructs originating in social interaction and distributed in the memory of the group members. The individual has his own perspective on the collective frameworks of the group, and the group’s collective frameworks can be regarded as a common denominator of the individual outlooks on the framework.
In acts of remembering, the individual may actualize the depicted symbols in memory, but he could also employ precepts from the environment. The latter have been referred to as material or external frameworks of memory, suggesting their similar role as catalysts for processes of remembrance such as that of the hybrids in my paintings. It is only with reference to the hybrids, who work as messengers / mediators with a dual nature, that communicate between the past and the present, the internal and external space, that individual memory and group memory is in focus.
The exhibition at the Egyptian museum in Leipzig is my practical method to create a communicative memory, using hybrids as mediators in cultural transimission, as when the act refers to informal and everyday situations in which group members informally search for the past, it takes place in the communicative
162
memory. As explained in chapter one, the exhibition at the Egyptian museum in Leipzig is an act of remembering in search for the past with support of my paintings, which then can considered as part of the cultural memory.
In addition to the theoretical framework summarized above, I have applied my hypothesis practically in the form of the public exhibition, and shared the methodology with public audience from Cairo / Egypt and Leipzig / German in the form of visual art workshops and open discussions. I have also suggested an analyzed description of the meaning of hybrids in my artwork as mediators and messengers for the purpose of cultural transmission, as well as in relation to other artists’ work and use of a similar concept.
By using my hybrid creatures in my visual artwork, I am creating a bridge, mediators to represent both the past and the present, what we remember of the past, and how we understand the past. It is as explained in chapter two; that the hybridization methodology in terms of double membership represented in different cultures –Cairo / Egypt and Leipzig / Germany- can provide a framework which allows artistic discussions and could be individually interpreted, so individual cultures / individual memory can become transparent without losing their identities and turn into communicative memory. This transmission through the hybridization theoretical approech was explicitly clarified with the support of Krämer’s hypothesis. The practical attempt was examined by creating a relationship between the witness –me as an artist– and the audience –the exhibition visitors–, to cross space and time, not to bridge differences, rather to represent the contrasts transparently.
The Kin-making proposition is adopted by many academics and scholars in modern society and theoretical research; the topic was represented in the roots of the ancient Egyptian mindset and supported theoretically by similar understandings such as Haraway’s definition of kin-making. The practical implementation of kin- making can be observed in many of my artwork and was analyzed visually and artistically in chapter three.
My practical project outcome tested success by using hybrids in my paintings as mediators, it opened a communicative artistic discussion. This methodology gave a possible path of communication through paintings / visual analyses, and offered relativity through image self-interpretation.
In this work, practice-based research is conducted to rethink the understanding of aesthetics, especially in relation to current media art. Granted, we live in times when technologies merge with living organisms, but we also live in times that provide unlimited resources of knowledge and maker tools. I raise the question: In what way does the hybridization of living organisms and non-living technologies affect art audiences in the culture that may be defined as Maker culture? My hypothesis is that active participation of an audience in an artwork is inevitable for experiencing the artwork itself, while also suggesting that the impact of the umwelt changes the perception of an artwork. I emphasize artistic projects that unfold through mutual interaction among diverse peers, including humans, non-human organisms, and machines. In my thesis, I pursue collaborative scenarios that lead to the realization of artistic ideas: (1) the development of ideas by others influenced by me and (2) the materialization of my own ideas influenced by others. By developing the scenarios of collaborative work as an artistic experience, I conclude that the role of an artist in Maker culture is to mediate different types of knowledge and different positions, whereas the role of the audience is to actively engage in the artwork itself. At the same time, aesthetics as experience is triggered by the other, including living and non-living actors. It is intended that the developed methodologies could be further adapted in artistic practices, philosophy, anthropology, and environmental studies.
Urban Heat Transition in Berlin: Corporate Strategies, Political Conflicts, and Just Solutions
(2023)
In the field of urban climate policy, heat production and demand are key sectors for achieving a sustainable city. Heat production has to shift from fossil to renewable energies, and the heat demand of most buildings has to be reduced significantly via building retrofits. However, analyses of heat transition still lack its contextualization within entangled urban politico-economic processes and materialities and require critical socio-theoretical examination. Asking about the embeddedness of heat transition within social relations and its implications for social justice issues, this article discusses the challenges and opportunities of heat transition, taking Berlin as an example. It uses an urban political ecology perspective to analyze the materialities of Berlin’s heating-housing nexus, its politico-economic context, implications for relations of inequality and power, and its contested strategies. The empirical analysis identifies major disputes about the future trajectory of heat production and about the distribution of retrofit costs. Using our conceptual approach, we discuss these empirical findings against the idea of a more just heat transition. For this purpose, we discuss three policy proposals regarding cost distribution, urban heat planning, and remunicipalization of heat utilities. We argue that this conceptual approach provides huge benefits for debates around heat transition and, more generally, energy justice and just transitions.
Beyond metropolitan areas, many peripheral regions and their cities in Europe have, in manifold ways, been significantly shaped by industrialisation. In the context of the relocation of industrial production to other countries over the last decades, the question has been raised as to the role this heritage can play in futural regional development as well as the potential local identification with this history. Hence, this article seeks to analyse the perception of the industrial heritage in the Vogtland region, located alongside the border of three German federal states and the Czech Republic. It inquires as to the perception of the industrial heritage by the local population and related potential future narrations. Based on spontaneous and explorative interviews with local people as an empirical base, a discrepancy between the perception of the tangible and intangible dimensions of the industrial heritage can be observed. On the one hand, the tangible heritage like older factories and production complexes are seen as a functional legacy and an “eyesore” narrative is attributed to them. On the other hand, people often reference the personal and familial connection to the industry and highlight its importance for the historical development and the wealth of the region. But these positive associations are mainly limited to the intangible dimension and are disconnected from the material artefacts of industrial production.
The characteristic values of climatic actions in current structural design codes are based on a specified probability of exceedance during the design working life of a structure. These values are traditionally determined from the past observation data under a stationary climate assumption. However, this assumption becomes invalid in the context of climate change, where the frequency and intensity of climatic extremes varies with respect to time. This paper presents a methodology to calculate the non-stationary characteristic values using state of the art climate model projections. The non-stationary characteristic values are calculated in compliance with the requirements of structural design codes by forming quasi-stationary windows of the entire bias-corrected climate model data. Three approaches for the calculation of non-stationary characteristic values considering the design working life of a structure are compared and their consequences on exceedance probability are discussed.
Anhand der städtebaulichen und sozialen Transformation des östlichen Gründerzeitgebietes von Leipzig wird die Rolle von migrantischen Hausbesitzenden und in der Bausanierung Tätigen im Aufwertungsprozess untersucht. Der Zugang zum Gegenstand verbindet Fragen der Stadtsoziologie und der Denkmalforschung. Im sozialen Feld der Stadterneuerung wird die Revitalisierung des ehemals von Leerstand und Rückbau betroffenen Baubestandes ausgehandelt. Die Positionen der Akteur:innen im Feld werden durch ihre Ausstattung mit ökonomischem, aber auch sozialem und kulturellem Kapital bestimmt. Angehörige der Planungs- und Denkmalbehörden verfügen über institutionalisiertes Kulturkapital und stehen damit Kleineigentümer:innen, häufig Autodidakt:innen, gegenüber. Baudenkmale können über ihre Funktion als Geldanlage und Wohnraum hinaus Status repräsentieren und symbolisch angeeignet werden. Denkmalschutz dient dem öffentlichen Interesse am Erhalt historischer Bausubstanz. Bei Sanierungen bestehen die Herausforderungen der Vereinbarkeit von Konservierung und Modernisierung, der Finanzierbarkeit für Eigentümer:innen und der Sozialverträglichkeit für Bewohnende. Eine Darstellung der historischen Entwicklung des Leipziger Ostens zu Beginn der Analyse veranschaulicht die Abhängigkeit kultureller, sozialer und ökonomischer Werte des Baubestandes vom jeweiligen gesellschaftlichen Kontext. Planerische Konzepte für das Gebiet zeigen, dass eine sozioökonomische Stabilisierung und Imageverbesserung erreicht werden sollte durch das Aufgreifen von Potentialen, wie den denkmalgeschützten Bauten, dem zuziehenden alternativen Milieu und migrantischer Ökonomie. Es wird deutlich, dass nach einer initialen Ansässigkeit von Pionier:innen die öffentlichen Infrastrukturmaßnahmen und Denkmalausweisungen eine Inwertsetzung v. a. durch externe Anlegende vorbereiteten. Darauf aufbauend wurden anhand einer qualitativen Befragung die Erfahrungen von städtischen Mitarbeitenden, Fachleuten und im Quartier Engagierten denen von lokalen migrantischen Hausbesitzenden und im Bereich Sanierung Tätigen gegenübergestellt. Migrant:innengruppen haben den Stadtraum in einer Phase vorherrschender Abwanderung durch die Eröffnung von Geschäften und Institutionen sowie den Erwerb von Immobilien für sich erschlossen. Strukturelle Benachteiligungen, wie Diskriminierung auf dem Arbeitsmarkt, ihre Ansässigkeit im sozial stigmatisierten Gebiet sowie geringes ökonomisches Kapital versuchten sie durch den Einsatz von sozialem Kapital auszugleichen. Sanierungen erfolgten mit hoher Eigenleistung und Rückgriff auf private Netzwerke. Die Analyse des Erneuerungsprozesses im Leipziger Osten zeigt, dass in einer initialen Phase Pionier:innen von Planenden und der Denkmalpflege als essentiell für die Entwicklung angesehen wurden. Günstige Instandsetzungen durch Kleineigentümer:innen wurden akzeptiert, um Gebäude vor weiterem Verfall zu bewahren. Mit der zunehmenden Forderung nach Verwendung hochwertiger Materialen werden die Sanierungsleistungen nach ästhetischen und letztlich ökonomischen Kriterien bewertet. Gegenüber sozialen Folgen einer Aufwertung von Bausubstanz lässt sich eine unkritische Haltung der Denkmalpflege erkennen. Bei der Vermarktung der Bestände durch professionelle Investierende findet die Sozialgeschichte des Stadtteils wenig Berücksichtigung, positiv besetzte Merkmale des Quartiers, wie Multikulturalität werden selektiv aufgegriffen. Der Anteil migrantischer Akteur:innen an der Entwicklung wird durch die Öffentlichkeit unzureichend anerkannt. Auch die Wertschätzung von Planenden und im Quartier Engagierten erfolgt v. a. anhand des ökonomischen Status. Hohe Erwartungen an die Geschäftsstruktur und die Erscheinung des Straßenbildes können nicht erfüllt werden. Migrantische Hausbesitzende und im Bereich Sanierung Tätige benötigen für die Auseinandersetzung mit der Denkmalpflege kulturelles Kapital. Sie erkennen die Bedeutung des historischen Baubestandes für die Stadt und die Arbeit der Institution an, kritisieren jedoch Sanierungsauflagen bzw. Mitarbeitende der Denkmalpflege und können sich z. T. gegen diese behaupten. Lokale migrantische Kleineigentümer:innen leisten durch ihre Quartiersbindung einen Beitrag zur ökonomischen und sozialen Stabilisierung. Mit ihrer Aufstiegsorientierung fördern sie in der Vermietungspraxis jedoch nur bedingt die Integration anderer Migrant:innen und grenzen sich von statusniedrigen Gruppen im Quartier ab. Migrantische Hausbesitzende und Unternehmende nehmen sich selbst als erfolgreiche Vorreitende in einer heterogener werdenden ostdeutschen Stadtgesellschaft wahr. Sie erkannten frühzeitig das Entwicklungspotential und gehören zu den Initiierenden und Profitierenden der Inwertsetzung.
Search engines are very good at answering queries that look for facts. Still, information needs that concern forming opinions on a controversial topic or making a decision remain a challenge for search engines. Since they are optimized to retrieve satisfying answers, search engines might emphasize a specific stance on a controversial topic in their ranking, amplifying bias in society in an undesired way. Argument retrieval systems support users in forming opinions about controversial topics by retrieving arguments for a given query. In this thesis, we address challenges in argument retrieval systems that concern integrating them in search engines, developing generalizable argument mining approaches, and enabling frame-guided delivery of arguments.
Adapting argument retrieval systems to search engines should start by identifying and analyzing information needs that look for arguments. To identify questions that look for arguments we develop a two-step annotation scheme that first identifies whether the context of a question is controversial, and if so, assigns it one of several question types: factual, method, and argumentative. Using this annotation scheme, we create a question dataset from the logs of a major search engine and use it to analyze the characteristics of argumentative questions. The analysis shows that the proportion of argumentative questions on controversial topics is substantial and that they mainly ask for reasons and predictions. The dataset is further used to develop a classifier to uniquely map questions to the question types, reaching a convincing F1-score of 0.78.
While the web offers an invaluable source of argumentative content to respond to argumentative questions, it is characterized by multiple genres (e.g., news articles and social fora). Exploiting the web as a source of arguments relies on developing argument mining approaches that generalize over genre. To this end, we approach the problem of how to extract argument units in a genre-robust way. Our experiments on argument unit segmentation show that transfer across genres is rather hard to achieve using existing sequence-to-sequence models.
Another property of text which argument mining approaches should generalize over is topic. Since new topics appear daily on which argument mining approaches are not trained, argument mining approaches should be developed in a topic-generalizable way. Towards this goal, we analyze the coverage of 31 argument corpora across topics using three topic ontologies. The analysis shows that the topics covered by existing argument corpora are biased toward a small subset of easily accessible controversial topics, hinting at the inability of existing approaches to generalize across topics. In addition to corpus construction standards, fostering topic generalizability requires a careful formulation of argument mining tasks. Same side stance classification is a reformulation of stance classification that makes it less dependent on the topic. First experiments on this task show promising results in generalizing across topics.
To be effective at persuading their audience, users of an argument retrieval system should select arguments from the retrieved results based on what frame they emphasize of a controversial topic. An open challenge is to develop an approach to identify the frames of an argument. To this end, we define a frame as a subset of arguments that share an aspect. We operationalize this model via an approach that identifies and removes the topic of arguments before clustering them into frames. We evaluate the approach on a dataset that covers 12,326 frames and show that identifying the topic of an argument and removing it helps to identify its frames.
When predicting sound pressure levels induced by structure-borne sound sources and describing the sound propagation path through the building structure as exactly as possible, it is necessary to characterize the vibration behavior of the structure-borne sound sources. In this investigation, the characterization of structure-borne sound sources was performed using the two-stage method (TSM) described in EN 15657. Four different structure-borne sound sources were characterized and subsequently installed in a lightweight test stand. The resulting sound pressure levels in an adjacent receiving room were measured. In the second step, sound pressure levels were predicted according to EN 12354-5 based on the parameters of the structure-borne sound sources. Subsequently, the predicted and the measured sound pressure levels were compared to obtain reliable statements on the achievable accuracy when using source quantities determined by TSM with this prediction method.
This paper presents initial findings from the empirical analysis of community based social enterprise (SE) and non-profit organisation (NPO) ecosystems in Johannesburg. SEs and NPOs are widely recognised as contributors to the resilience of marginalised urban communities. However, the connection between these organisations , urban governance, and community resilience has not yet been sufficiently understood , particularly in African urban contexts. The 'Resilient Urban Communities' project focuses on Johannesburg as a case study to shed light on this under-researched topic. The key to exploring it is understanding SEs and NPOs as providers of public services, job creators, and promoters of good governance, all of which contribute to community resilience. Using this premise as a starting point, this paper investigates ecosystem conditions with a particular focus on state-civil society partnerships. Empirical data was generated through semi-struc-tured interviews and analysed with a grounded theory approach. Preliminary results of this ongoing research reveal that urban geography is a relevant ecosystem factor for SEs and NPOs from marginalised communities. We also suggest that co-production could be an opportunity for growth within the investigated state-civil society partnership.
As an optimization that starts from a randomly selected structure generally does not guarantee reasonable optimality, the use of a systemic approach, named the ground structure, is widely accepted in steel-made truss and frame structural design. However, in the case of reinforced concrete (RC) structural optimization, because of the orthogonal orientation of structural members, randomly chosen or architect-sketched framing is used. Such a one-time fixed layout trend, in addition to its lack of a systemic approach, does not necessarily guarantee optimality. In this study, an approach for generating a candidate ground structure to be used for cost or weight minimization of 3D RC building structures with included slabs is developed. A multiobjective function at the floor optimization stage and a single objective function at the frame optimization stage are considered. A particle swarm optimization (PSO) method is employed for selecting the optimal ground structure. This method enables generating a simple, yet potential, real-world representation of topologically preoptimized ground structure while both structural and main architectural requirements are considered. This is supported by a case study for different floor domain sizes.
One of the main criteria determining the thermal comfort of occupants is the air temperature. To monitor this parameter, a thermostat is traditionally mounted in the indoor environment for instance in office rooms in the workplaces, or directly on the radiator or in another location in a room. One of the drawbacks of this conventional method is the measurement at a certain location instead of the temperature distribution in the entire room including the occupant zone. As a result, the climatic conditions measured at the thermostat point may differ from those at the user's location. This not only negatively impacts the thermal comfort assessment but also leads to a waste of energy due to unnecessary heating and cooling. Moreover, for measuring the distribution of the air temperature under laboratory conditions, multiple thermal sensors should be installed in the area under investigation. This requires high effort in both installation and expense.
To overcome the shortcomings of traditional sensors, Acoustic travel-time TOMography (ATOM) offers an alternative based on measuring the transmission sound velocity signals. The basis of the ATOM technique is the first-order dependency of the sound velocity on the medium's temperature. The average sound velocity, along the propagation paths, can be determined by travel-times estimation of a defined acoustic signal between transducers. After the travel-times collection, the room is divided into several volumetric grid cells, i.e. voxels, whose sizes are defined depending on the dimension of the room and the number of sound paths. Accordingly, the spatial air temperature in each voxel can be determined using a suitable tomographic algorithm. Recent studies indicate that despite the great potential of this technique to detect room climate, few experiments have been conducted.
This thesis aims to develop the ATOM technique for indoor climatic applications while coupling the analysis methods of tomography and room acoustics. The method developed in this thesis uses high-energy early reflections in addition to the direct paths between transducers for travel time estimation. In this way, reflections can provide multiple sound paths that allow the room coverage to be maintained even when a few or even only one transmitter and receiver are used.
In the development of the ATOM measurement system, several approaches have been employed, including the development of numerical methods and simulations and conducting experimental measurements, each of which has contributed to the improvement of the system's accuracy. In order to effectively separate the early reflections and ensure adequate coverage of the room with sound paths, a numerical method was developed based on the optimization of the coordinates of the sound transducers in the test room. The validation of the optimal positioning method shows that the reconstructed temperatures were significantly improved by placing the transducers at the optimal coordinates derived from the developed numerical method. The other numerical method developed is related to the selection of the travel times of the early reflections. Accordingly, the detection of the travel times has been improved by adjusting the lengths of the multiple analysis time-windows according to the individual travel times in the reflectogram of the room impulse response. This can reduce the probability of trapping faulty travel times in the analysis time-windows.
The simulation model used in this thesis is based on the image source model (ISM) method for simulating the theoretical travel times of early reflection sound paths. The simulation model was developed to simulate the theoretical travel times up to third-order reflections.
The empirical measurements were carried out in the climate lab of the Chair of Building Physics under different boundary conditions, i.e., combinations of different room air temperatures under both steady-state and transient conditions, and different measurement setups. With the measurements under controllable conditions in the climate lab, the validity of the developed numerical methods was confirmed.
In this thesis, the performance of the ATOM measurement system was evaluated using two measurement setups. The setup for the initial investigations consists of an omnidirectional receiver and a near omnidirectional sound source, keeping the number of transducers as few as possible. This has led to accurately identify the sources of error that could occur in each part of the measuring system. The second measurement setup consists of two directional sound sources and one omnidirectional receiver. This arrangement of transducers allowed a higher number of well-detected travel times for tomography reconstruction, a better travel time estimation due to the directivity of the sound source, and better space utilization. Furthermore, this new measurement setup was tested to determine an optimal selection of the excitation signal. The results showed that for the utilized setup, a linear chirp signal with a frequency range of 200 - 4000 Hz and a signal duration of t = 1 s represents an optimal selection with respect to the reliability of the measured travel times and higher signal-to-noise ratio (SNR).
To evaluate the performance of the measuring setups, the ATOM temperatures were always compared with the temperatures of high-resolution NTC thermistors with an accuracy of ±0.2 K. The entire measurement program, including acoustic measurements, simulation, signal processing, and visualization of measurement results are performed in MATLAB software.
In addition, to reduce the uncertainty of the positioning of the transducers, the acoustic centre of the loudspeaker was determined experimentally for three types of excitation signals, namely MLS (maximum length sequence) signals with different lengths and duration, linear and logarithmic chirp signals with different defined frequency ranges. For this purpose, the climate lab was converted into a fully anechoic chamber by attaching absorption panels to the entire surfaces of the room. The measurement results indicated that the measurement of the acoustic centre of the sound source significantly reduces the displacement error of the transducer position.
Moreover, to measure the air temperature in an occupied room, an algorithm was developed that can convert distorted signals into pure reference signals using an adaptive filter. The measurement results confirm the validity of the approach for a temperature interval of 4 K inside the climate lab.
Accordingly, the accuracy of the reconstructed temperatures indicated that ATOM is very suitable for measuring the air temperature distribution in rooms.
The release of the large language model-based chatbot ChatGPT 3.5 in November 2022 has brought considerable attention to the subject of artificial intelligence, not only to the public. From the perspective of higher education, ChatGPT challenges various learning and assessment formats as it significantly reduces the effectiveness of their learning and assessment functionalities. In particular, ChatGPT might be applied to formats that require learners to generate text, such as bachelor theses or student research papers. Accordingly, the research question arises to what extent writing of bachelor theses is still a valid learning and assessment format. Correspondingly, in this exploratory study, the first author was asked to write his bachelor’s thesis exploiting ChatGPT. For tracing the impact of ChatGPT methodically, an autoethnographic approach was used. First, all considerations on the potential use of ChatGPT were documented in logs, and second, all ChatGPT chats were logged. Both logs and chat histories were analyzed and are presented along with the recommendations for students regarding the use of ChatGPT suggested by a common framework. In conclusion, ChatGPT is beneficial for thesis writing during various activities, such as brainstorming, structuring, and text revision. However, there are limitations that arise, e.g., in referencing. Thus, ChatGPT requires continuous validation of the outcomes generated and thus fosters learning. Currently, ChatGPT is valued as a beneficial tool in thesis writing. However, writing a conclusive thesis still requires the learner’s meaningful engagement. Accordingly, writing a thesis is still a valid learning and assessment format. With further releases of ChatGPT, an increase in capabilities is to be expected, and the research question needs to be reevaluated from time to time.
Die Planungsforschung hat sich spätestens seit der „kommunikativen Wende“ intensiv damit beschäftigt, wie mit Konflikten umgegangen werden soll und wird. Ansätze der „agonistischen“ Planungstheorie widersprechen der normativen Prämisse, Konsensbildung unter den Planungsbeteiligten anzustreben. Vielmehr wollen sie widerstreitende Positionen normativ für die räumliche Entwicklung fruchtbar machen. Zugleich betonen sie eine vermeintliche Dualität von Planung und Protest, die in der neueren Protesttheorie infrage gestellt wird. Dieser Beitrag zeigt aufbauend auf einer Diskussion von planungs- und protesttheoretischen Ansätzen und einer empirischen Analyse planungsbezogener Proteste in Deutschland, dass diese Proteste von den Planungsakteuren zwar immer stärker als „Normalität“ aufgefasst werden und antagonistische Partizipation trotz zunehmender Konflikthaftigkeit und vermeintlicher Infragestellung der repräsentativen Demokratie kulturell regelgebunden bleibt. Protesthandeln ist Teil ausdifferenzierter „Partizipationsbündel“, die situationsbezogen auch Teilnahme an Beteiligungsverfahren, direktdemokratische Verfahren und Klagen umfassen. Protestierende verfolgen dabei meist eine eher reformorientierte Agenda, die keiner „Zähmung“ bedarf. Allerdings können die zugrunde liegenden Konflikte häufig gar nicht „gelöst“ werden. Planenden hingegen können auch innerhalb eines agonistischen Planungsumfelds rationalistische und deliberative Ansätze zur Verfügung stehen, die sie situationsbezogen und strategisch nutzen.
Experimental Validation of Dynamic Response of Small-Scale Metaconcrete Beams at Resonance Vibration
(2023)
Structures and their components experience substantially large vibration amplitudes at resonance, which can cause their failure. The scope of this study is the utilization of silicone-coated steel balls in concrete as damping aggregates to suppress the resonance vibration. The heavy steel cores oscillate with a frequency close to the resonance frequency of the structure. Due to the phase difference between the vibrations of the cores and the structure, the cores counteract the vibration of the structure. The core-coating inclusions are randomly distributed in concrete similar to standard aggregates. This mixture is referred to as metaconcrete. The main goal of this work is to validate the ability of the inclusions to suppress mechanical vibration through laboratory experiments. For this purpose, two small-scale metaconcrete beams were cast and tested. In a free vibration test, the metaconcrete beams exhibited a larger damping ratio compared to a similar beam cast from conventional concrete. The vibration amplitudes of the metaconcrete beams at resonance were measured with a frequency sweep test. In comparison with the conventional concrete beam, both metaconcrete beams demonstrated smaller vibration amplitudes. Both experiments verified an improvement in the dynamic response of the metaconcrete beams at resonance vibration.