Refine
Document Type
- Article (34)
- Doctoral Thesis (30)
- Book (4)
- Study Thesis (4)
- Conference Proceeding (3)
- Preprint (3)
- Review (3)
- Master's Thesis (2)
- Periodical (2)
- Bachelor Thesis (1)
Institute
- Institut für Strukturmechanik (ISM) (17)
- F. A. Finger-Institut für Baustoffkunde (FIB) (5)
- Professur Bauphysik (5)
- Professur Sozialwissenschaftliche Stadtforschung (5)
- Hochschule für Musik FRANZ LISZT (4)
- Institut für Europäische Urbanistik (4)
- Institut für Konstruktiven Ingenieurbau (IKI) (3)
- Professur Angewandte Mathematik (3)
- Professur Baubetrieb und Bauverfahren (3)
- Professur Content Management und Webtechnologien (3)
Keywords
- OA-Publikationsfonds2021 (13)
- Kulturerbe (4)
- Maschinelles Lernen (4)
- Beton (3)
- Finite-Elemente-Methode (3)
- Frost (3)
- Allgemeiner Deutscher Musikverein (2)
- Architektur (2)
- BIM (2)
- Bauantrag (2)
Year of publication
- 2021 (88) (remove)
Polylactic acid (PLA) is a highly applicable material that is used in 3D printers due to some significant features such as its deformation property and affordable cost. For improvement of the end-use quality, it is of significant importance to enhance the quality of fused filament fabrication (FFF)-printed objects in PLA. The purpose of this investigation was to boost toughness and to reduce the production cost of the FFF-printed tensile test samples with the desired part thickness. To remove the need for numerous and idle printing samples, the response surface method (RSM) was used. Statistical analysis was performed to deal with this concern by considering extruder temperature (ET), infill percentage (IP), and layer thickness (LT) as controlled factors. The artificial intelligence method of artificial neural network (ANN) and ANN-genetic algorithm (ANN-GA) were further developed to estimate the toughness, part thickness, and production-cost-dependent variables. Results were evaluated by correlation coefficient and RMSE values. According to the modeling results, ANN-GA as a hybrid machine learning (ML) technique could enhance the accuracy of modeling by about 7.5, 11.5, and 4.5% for toughness, part thickness, and production cost, respectively, in comparison with those for the single ANN method. On the other hand, the optimization results confirm that the optimized specimen is cost-effective and able to comparatively undergo deformation, which enables the usability of printed PLA objects.
Burning of clinker is the most influencing step of cement quality during the production process. Appropriate characterisation for quality control and decision-making is therefore the critical point to maintain a stable production but also for the development of alternative cements. Scanning electron microscopy (SEM) in combination with energy dispersive X-ray spectroscopy (EDX) delivers spatially resolved phase and chemical information for cement clinker. This data can be used to quantify phase fractions and chemical composition of identified phases.
The contribution aims to provide an overview of phase fraction quantification by semi-automatic phase segmentation using high-resolution backscattered electron (BSE) images and lower-resolved EDX element maps. Therefore, a tool for image analysis was developed that uses state-of-the-art algorithms for pixel-wise image segmentation and labelling in combination with a decision tree that allows searching for specific clinker phases. Results show that this tool can be applied to segment sub-micron scale clinker phases and to get a quantification of all phase fractions. In addition, statistical evaluation of the data is implemented within the tool to reveal whether the imaged area is representative for all clinker phases.
This study demonstrates the application and combination of multiple imaging techniques [light microscopy, micro-X-ray computer tomography (μ-CT), scanning electron microscopy (SEM) and focussed ion beam – nano-tomography (FIB-nT)] to the analysis of the microstructure of hydrated alite across multiple scales. However, by comparing findings with mercury intrusion porosimetry (MIP), it becomes obvious that the imaged 3D volumes and 2D images do not sufficiently overlap at certain scales to allow a continuous quantification of the pore size distribution (PSD). This can be overcome by improving the resolution and increasing the measured volume. Furthermore, results show that the fibrous morphology of calcium-silicate-hydrates (C-S-H) phases is preserved during FIB-nT. This is a requirement for characterisation of nano-scale porosity. Finally, it was proven that the combination of FIB-nT with energy-dispersive X-ray spectroscopy (EDX) data facilitates the phase segmentation of a 11 × 11 × 7.7 μm3 volume of hydrated alite.
Within the scope of literature, the influence of openings within the infill walls that are bounded by a reinforced concrete frame and excited by seismic drift forces in both in- and out-of-plane direction is still uncharted. Therefore, a 3D micromodel was developed and calibrated thereafter, to gain more insight in the topic. The micromodels were calibrated against their equivalent physical test specimens of in-plane, out-of-plane drift driven tests on frames with and without infill walls and openings, as well as out-of-plane bend test of masonry walls. Micromodels were rectified based on their behavior and damage states. As a result of the calibration process, it was found that micromodels were sensitive and insensitive to various parameters, regarding the model’s behavior and computational stability. It was found that, even within the same material model, some parameters had more effects when attributed to concrete rather than on masonry. Generally, the in-plane behavior of infilled frames was found to be largely governed by the interface material model. The out-of-plane masonry wall simulations were governed by the tensile strength of both the interface and masonry material model. Yet, the out-of-plane drift driven test was governed by the concrete material properties.
Realistic uncertainty description incorporating aleatoric and epistemic uncertainties can be described within the framework of polymorphic uncertainty, which is computationally demanding. Utilizing a domain decomposition approach for random field based uncertainty models the proposed level-based sampling method can reduce these computational costs significantly and shows good agreement with a standard sampling technique. While 2-level configurations tend to get unstable with decreasing sampling density 3-level setups show encouraging results for the investigated reliability analysis of a structural unit square.
Bauhaus-Gastprofessorin Mirjam Wenzel referierte am 30. Juni 2021 im Audimax der Bauhaus-Universität Weimar zur Entstehungsgeschichte und Konzeption Jüdischer Museen. Dabei ging sie darauf ein, inwiefern diese Museen besonders relevant für aktuelle gesellschaftliche und politische Fragestellungen sind. Prof. Wenzels zweiter öffentlicher Vortrag an der Bauhaus-Universität Weimar skizzierte die Potentiale von Kultureinrichtungen in Zeiten gesellschaftspolitischer Veränderungen im Allgemeinen und die Bedeutung Jüdischer Museen angesichts verbaler und tätlicher Gewalt gegen Jüdinnen und Juden im Besonderen.
Compiling and disseminating information about incidents and disasters are key to disaster management and relief. But due to inherent limitations of the acquisition process, the required information is often incomplete or missing altogether. To fill these gaps, citizen observations spread through social media are widely considered to be a promising source of relevant information, and many studies propose new methods to tap this resource. Yet, the overarching question of whether and under which circumstances social media can supply relevant information (both qualitatively and quantitatively) still remains unanswered. To shed some light on this question, we review 37 disaster and incident databases covering 27 incident types, compile a unified overview of the contained data and their collection processes, and identify the missing or incomplete information. The resulting data collection reveals six major use cases for social media analysis in incident data collection: (1) impact assessment and verification of model predictions, (2) narrative generation, (3) recruiting citizen volunteers, (4) supporting weakly institutionalized areas, (5) narrowing surveillance areas, and (6) reporting triggers for periodical surveillance. Furthermore, we discuss the benefits and shortcomings of using social media data for closing information gaps related to incidents and disasters.
Chemical glass frosting processes are widely used to create visual attractive glass surfaces. A commonly used frosting bath mainly contains ammonium bifluoride (NH4HF2) mixed with hydrochloric acid (HCl). The frosting process consists of several baths. Firstly, the preliminary bath to clean the object. Secondly, the frosting bath which etches the rough light scattering structure into the glass surface. Finally, the washing baths to clean the frosted object. This is where the constituents of the preceding steps accumulate and have to be filtered from the sewage. In the present contribution, phosphoric acid (H3PO4) was used as a substitute for HCl to reduce the amount of ammonium (NH4+) and chloride (Cl−) dissolved in the waste water. In combination with magnesium carbonate (MgCO3), it allows the precipitation of ammonium within the sewage as ammonium magnesium phosphate (MgNH4PO4). However, a trivial replacement of HCl by H3PO4 within the frosting process causes extensive frosting errors, such as inhomogeneous size distributions of the structures or domains that are not fully covered by these structures. By modifying the preliminary bath composition, it was possible to improve the frosting result considerably. To determine the optimal composition of the preliminary bath, a semi-automatic evaluation method has been developed. This method renders the objective comparison of the resulting surface quality possible.
Entrepreneurship and start-up activities are seen as a key response to recent upheavals in the media industry: Newly founded ventures can act as important drivers for industry transformation and renewal, pioneering new products, business models, and organizational designs (e.g. Achtenhagen, 2017; Buschow & Laugemann, 2020).
In principle, media students represent a crucial population of nascent entrepreneurs: individuals who will likely become founders of start-ups (Casero-Ripollés et al., 2016). However, their willingness to start a new business is generally considered to be rather low (Goyanes, 2015), and for journalism students, the idea of innovation tends to be conservative, following traditional norms and professional standards (Singer & Broersma, 2020). In a sample of Spanish journalism students, López-Meri et al. (2020) found that one of the main barriers to entrepreneurial intentions is that students feel they lack knowledge and training in entrepreneurship.
In the last 10 years, a wide variety of entrepreneurship education courses have been set up in media departments of colleges and universities worldwide.
These programs have been designed to sensitize and prepare communications, media and journalism students to think and act entrepreneurially (e.g. Caplan et al., 2020; Ferrier, 2013; Ferrier & Mays, 2017; Hunter & Nel, 2011). Entrepreneurial competencies
and practices not only play a crucial role for start-ups, but, in imes of digital transformation, are increasingly sought after by legacy media companies as well (Küng, 2015).
At the Department of Journalism and Communication Research, Hanover University of Music, Drama and Media, Germany, we have been addressing these developments with the “Media Entrepreneurship” program. The course, established in 2013, aims to provide fundamental knowledge of entrepreneurship, as well as promoting students‘ entrepreneurial thinking and behavior. This article presents the pedagogical approach of the program and investigates learning outcomes. By outlining and evaluating the Media Entrepreneurship program, this article aims to promote good practices of entrepreneurship education in communications, media and journalism, and to reflect on the limitations of such programs.
Utilizing Modern FIB/SEM Technology and EDS for 3D Imaging of Hydrated Alite and its Pore Space
(2021)
The exploration of cementitious materials using scanning electron microscopes (SEM) is mainly done using fractured or polished surfaces. This leads to high-resolution 2D-images that can be combined using EDX and EBSD to unveil details of the microstructure and composition of materials. Nevertheless, this does not provide a quantitative insight into the three-dimensional fine structure of for example C-S-H phases.
The focused ion beam (FIB) technology can cut a block of material in thin layers of less than 10 nm. This gives us a volume of 1000 μm³ with a voxel resolution of down to 4 x 4 x 10 nm³. The results can be combined with simultaneously acquired EDX data to improve image segmentation. Results of the investigation demonstrate that it is possible to obtain close-to-native 3D-visualisation of the spatial distribution of unreacted C3S, C-S-H and CH. Additionally, an optimized preparation method allows us to quantify the fine structure of C-S-H phases (length, aspect ratio, …) and the pore space.
Überwachungspraktiken und –technologien sind in der heutigen Welt omnipräsent und wohl nicht mehr wegzudenken. Ob CCTV-Systeme, Biometrie oder Data Mining – unsere Gesellschaft befindet sich in einem ständigen Überwachungsmodus, der sich weit über einen begrenzten Raum oder zeitlichen Rahmen hinausstreckt. Überwacht wird überall: privat, am Arbeitsplatz oder im Cyberspace, und alles: Interaktionen, Äußerungen, Verhalten. Es werden Unmengen von Daten gesammelt, strukturiert, kombiniert, gekauft und verkauft.
Dieser Modus stellt mehr als eine bloße Neuauflage des Bentham-Foucaultschen Panoptikons dar: der aktuelle Überwachungsmodus, die informationelle Asymmetrie als ihren tragenden Pfeiler beibehaltend, dient nicht nur der Disziplinierung, sondern viel mehr der Kontrolle, die nicht primär negativ-sanktionierend, sondern positiv-leistungssteigernd wirkt: es ist nicht das Ziel, die Individuen zu bestrafen und ein bestimmtes Verhalten zu verbieten, sondern sie durch Belohnung, Interaktion und spielerische Elemente dazu zu bringen, sich auf die gewünschte Art zu verhalten und im Endeffekt sich selbst zu überwachen. Die Kontrolle wird auf diese Weise zum zentralen Schauplatz der Machtausübung, die sich über das Beobachten, Speichern, Auswerten und Sortieren vollzieht. Diese Prozesse hinterlassen keinen Frei- oder Spielraum für Ambiguität; sie verwirklichen die Diktatur der klaren Kante, der Klassifizierung und Kategorisierung ohne Schattierungen. Die Macht selbst befindet sich in einem kontinuierlichen Fluss, sie ist ubiquitär, dennoch schwer lokalisierbar. Sie fungiert nicht mehr unter dem Signum einer pseudosakralen zentralen Instanz, sondern wird durch diverse Akteure und Assemblages kolportiert. Die durch sie implizierten Praktiken der Selbstkontrolle, kulturgeschichtlich ebenfalls religiös oder zumindest philosophisch konnotiert, sind die neuen Rituale des Sehens und Gesehen-Werdens.
Im Zeitalter der elektronischen Datentechnologien gibt es diverse Agenten der Überwachung. Vom besonderen Interesse sind dabei die Wearables, weil sie intim, affektiv und haptisch arbeiten und so, über das Sehen und Gesehen-Werden hinaus, das Berühren und Berührt-Werden und somit die Neuregulierung von Nähe und Distanz ins Spiel bringen. Sie schreiben sich zwar in eine Vermessungstradition eins, die ihre Ursprünge mindestens im 19. Jahrhundert hat, unterscheiden sich aber von dieser in ihrer Intensität und Sinnlichkeit.
This article is focused on the research and development of new cellulose ether derivatives as innovative superplasticizers for mortar systems. Several synthetic strategies have been pursued to obtain new compounds to study their properties on cementitious systems as new bio-based additives. The new water-soluble admixtures were synthesized using a complex carboxymethylcellulose-based backbone that was first hydrolyzed and then sulfo-ethylated in the presence of sodium vinyl sulphonate. Starting with a complex biopolymer that is widely known as a thickening agent was very challenging. Only by varying the hydrolysis times and temperatures of the reactions was achieved the aimed goal. The obtained derivatives showed different molecular weight (Mw) and anionic charges on their backbones. An improvement in shear stress and dynamic viscosity values of CEM II 42.5R cement was observed with the samples obtained with a longer time of higher temperature hydrolysis and sulfo-ethylation. Investigations into the chemical nature of the pore solution, calorimetric studies and adsorption experiments clearly showed the ability of carboxymethyl cellulose superplasticizer (CMC SP) to interact with cement grains and influence hydration processes within a 48-h time window, causing a delay in hydration reactions in the samples. The fluidity of the cementitious matrices was ascertained through slump test and preliminary studies of mechanical and flexural strength of the hardened mortar formulated with the new ecological additives yielded values in terms of mechanical properties. Finally, the computed tomography (CT) images completed the investigation of the pore network structure of hardened specimens, highlighting their promising structure porosity.
The computational analysis of argumentation strategies is substantial for many downstream applications. It is required for nearly all kinds of text synthesis, writing assistance, and dialogue-management tools. While various tasks have been tackled in the area of computational argumentation, such as argumentation mining and quality assessment, the task of the computational analysis of argumentation strategies in texts has so far been overlooked.
This thesis principally approaches the analysis of the strategies manifested in the persuasive argumentative discourses that aim for persuasion as well as in the deliberative argumentative discourses that aim for consensus. To this end, the thesis presents a novel view of argumentation strategies for the above two goals. Based on this view, new models for pragmatic and stylistic argument attributes are proposed, new methods for the identification of the modelled attributes have been developed, and a new set of strategy principles in texts according to the identified attributes is presented and explored.
Overall, the thesis contributes to the theory, data, method, and evaluation aspects of the analysis of argumentation strategies. The models, methods, and principles developed and explored in this thesis can be regarded as essential for promoting the applications mentioned above, among others.
“How to understand the interaction between urban space and social processes” is a significant question in urban studies. To answer that, the city needs to be recognized as both a physical and a social entity and urban theory and practice need to connect these (Hillier 2007). The present research aims to re-examine the complex correlation between spatial and social inequality manifestations in the city of Tehran regarding the concept of segregation.
It observes the causes and consequences of segregation in Tehran and provides an insight into both concepts of socio-spatial segregation and neighborhood effects and creates a link between them. First, I argue when, where, and for whom spatial locations affect the chances of social networks in Tehran. Then, I discuss how neighborhood effects can emerge via social network mechanisms and thus affect the perceptions of residents in the neighborhoods.
Die interdisziplinäre Dissertationsschrift lässt sich im Horizont internationaler Forschungen zu Denkmalwerten, neuer Ansätze in der Kultur- und Wissensvermittlung rund um Baudenkmale sowie künstlerisch- ethnographischem Forschen an und mit Denkmalen verorten.
Der erste Teil der Arbeit widmet sich Denkmalen und der Denkmalpflege im Kontext künstlerischer und sozialwissenschaftlicher Allianzen. Ausgangspunkt ist die Feststellung, dass die Denkmalpflege zwar sehr vieles über Denkmale weiß, aber kaum etwas über deren Rezeption beim breiten Publikum. Im Mittelpunkt steht die Frage, wie hier Praktiken der bildenden Kunst und Arbeitsweisen der Kulturanthropologie die Disziplin der Denkmalpflege bereichern können, oder sogar müssen.
Den zweiten Teil bildet eine empirische Studie, in der die populäre Wahrnehmung von Denkmalen qualitativ erforscht wird. Das Schloss und Rittergut Bedheim im südlichen ländlichen Thüringen dient dabei als konkreter Untersuchungsort. Reaktionen von Besucherinnen und Besuchern werden mit Hilfe von drei künstlerischen Eingriffen angeregt und diese dann ethnographisch-offen dokumentiert und ausgewertet.
Auf dieser Basis werden Zugänge zum Denkmal ermittelt. Während die meisten BesucherInnen das Denkmal als „Arbeit“ wahrnehmen, geraten einige ins „Träumen“ oder „Erinnern“, man „genießt“ das Ensemble als authentische und ästhetische Ressource, oder findet Zugang über das spontane „Erklären“ baukonstruktiver oder baulicher Situationen. Für andere bedeutet der Besuch die „Teilhabe“ an einem Prozess. Schloss Bedheim wird als Ort stetiger Veränderung geschätzt. In der Wahrnehmung der BesucherInnen verquicken sich Aspekte des Bewunderns mit solchen des Abgrenzens. Die eigene Alltagswelt und das eigene Zuhause bilden hierbei Bezugspunkte. Schloss Bedheim wird auf diese Weise zum Imaginationsraum, zur Energietankstelle und zur gern besuchten Problemwelt.
Die Ergebnisse der Arbeit liegen in zwei Erkenntnisfeldern: Auf einer methodischen Ebene zeigt sie, wie in der Denkmalpflege vertiefte Fachlichkeit mit einer tatsächlichen Kontaktaufnahme mit dem Publikum verbunden werden kann und damit soziale Gefüge an Baudenkmalen qualitativ ermittelt werden können. Ebenso wird deutlich, dass künstlerische Eingriffe Auslöser von Gesprächen sind, als Kontaktflächen zur Alltagswelt dienen und so zu einer vielfältigen Auseinandersetzung mit Denkmalen führen.
Auf einer inhaltlichen Ebene liefert die Arbeit Erkenntnisse zu Wahrnehmungsweisen von Denkmalen. Neben den erwähnten Zugängen, wird die Existenz und Bedeutung einer regional vernetzten Wahrnehmung von Denkmalen aufgedeckt. Des Weiteren zeigen die Ergebnisse, dass das Öffnen von Baudenkmalen als und im Prozess ungenutzte Potentiale birgt und es wird angeregt, dies in zukünftigen denkmalpflegerischen Konzepten eine größere Rolle spielen zu lassen. Die Vision eines „Kompendiums der Zugänge“ wird entwickelt, mit dessen Hilfe sich ein enormes Wissen über Rollen und Bedeutungen die Baudenkmale in unserer Gesellschaft spielen, sammeln ließe.
This thesis examines urban partition in Nicosia, the capital of Cyprus, and how its changing roles and shifting perceptions in a post-conflict setting reflect power relations, and their constant renegotiation. Nicosia, the capital of Cyprus, was officially divided in 1974 in the aftermath of an eighteen-year-long conflict between the island’s Turkish- and Greek-Cypriot communities. As a result, a heavily militarized Buffer Zone, established as an emergency measure against perpetuation of intercommunal violence, has been cutting through its historic centre ever since.
This thesis departs from a genuine interest in the material and ideational dimensions of urban partition. How is it constructed, not merely in physical terms but in the minds of the societies affected by conflict? How is it established in official and everyday discourses? What kinds of mechanisms have been developed to maintain it, and make an inseparable part of the urban experience? Moreover, taking into account the consensus in relevant literature pertaining to the imperative for its removal, this thesis is inquiring into the relevance of peace agreements to overcoming urban partition. For this purpose, it also looks at narratives and practices that have attempted to contest it.
The examples examined in this thesis offer pregnant analytical moments to understand Nicosia’s Buffer Zone as a dynamic social construct, accommodating multiple visions of and for the city. Its space ‘in-between’ facilitates encounters between various actors, accommodates new meanings, socio-spatial practices and diverse imaginaries. In this sense, urban partition is explored in this thesis as a phenomenon that transcends scales as well as temporalities, entwining past, present, and future.
This work presents a robust status monitoring approach for detecting damage in cantilever structures based on logistic functions. Also, a stochastic damage identification approach based on changes of eigenfrequencies is proposed. The proposed algorithms are verified using catenary poles of electrified railways track. The proposed damage features overcome the limitation of frequency-based damage identification methods available in the literature, which are valid to detect damage in structures to Level 1 only. Changes in eigenfrequencies of cantilever structures are enough to identify possible local damage at Level 3, i.e., to cover damage detection, localization, and quantification. The proposed algorithms identified the damage with relatively small errors, even at a high noise level.
This thesis presents the advances and applications of phase field modeling in fracture analysis. In this approach, the sharp crack surface topology in a solid is approximated by a diffusive crack zone governed by a scalar auxiliary variable. The uniqueness of phase field modeling is that the crack paths are automatically determined as part of the solution and no interface tracking is required. The damage parameter varies continuously over the domain. But this flexibility comes with associated difficulties: (1) a very fine spatial discretization is required to represent sharp local gradients correctly; (2) fine discretization results in high computational cost; (3) computation of higher-order derivatives for improved convergence rates and (4) curse of dimensionality in conventional numerical integration techniques. As a consequence, the practical applicability of phase field models is severely limited.
The research presented in this thesis addresses the difficulties of the conventional numerical integration techniques for phase field modeling in quasi-static brittle fracture analysis. The first method relies on polynomial splines over hierarchical T-meshes (PHT-splines) in the framework of isogeometric analysis (IGA). An adaptive h-refinement scheme is developed based on the variational energy formulation of phase field modeling. The fourth-order phase field model provides increased regularity in the exact solution of the phase field equation and improved convergence rates for numerical solutions on a coarser discretization, compared to the second-order model. However, second-order derivatives of the phase field are required in the fourth-order model. Hence, at least a minimum of C1 continuous basis functions are essential, which is achieved using hierarchical cubic B-splines in IGA. PHT-splines enable the refinement to remain local at singularities and high gradients, consequently reducing the computational cost greatly. Unfortunately, when modeling complex geometries, multiple parameter spaces (patches) are joined together to describe the physical domain and there is typically a loss of continuity at the patch boundaries. This decrease of smoothness is dictated by the geometry description, where C0 parameterizations are normally used to deal with kinks and corners in the domain. Hence, the application of the fourth-order model is severely restricted. To overcome the high computational cost for the second-order model, we develop a dual-mesh adaptive h-refinement approach. This approach uses a coarser discretization for the elastic field and a finer discretization for the phase field. Independent refinement strategies have been used for each field.
The next contribution is based on physics informed deep neural networks. The network is trained based on the minimization of the variational energy of the system described by general non-linear partial differential equations while respecting any given law of physics, hence the name physics informed neural network (PINN). The developed approach needs only a set of points to define the geometry, contrary to the conventional mesh-based discretization techniques. The concept of `transfer learning' is integrated with the developed PINN approach to improve the computational efficiency of the network at each displacement step. This approach allows a numerically stable crack growth even with larger displacement steps. An adaptive h-refinement scheme based on the generation of more quadrature points in the damage zone is developed in this framework. For all the developed methods, displacement-controlled loading is considered. The accuracy and the efficiency of both methods are studied numerically showing that the developed methods are powerful and computationally efficient tools for accurately predicting fractures.
In the last decades, Finite Element Method has become the main method in statics and dynamics analysis in engineering practice. For current problems, this method provides a faster, more flexible solution than the analytic approach. Prognoses of complex engineer problems that used to be almost impossible to solve are now feasible.
Although the finite element method is a robust tool, it leads to new questions about engineering solutions. Among these new problems, it is possible to divide into two major groups: the first group is regarding computer performance; the second one is related to understanding the digital solution.
Simultaneously with the development of the finite element method for numerical solutions, a theory between beam theory and shell theory was developed: Generalized Beam Theory, GBT. This theory has not only a systematic and analytical clear presentation of complicated structural problems, but also a compact and elegant calculation approach that can improve computer performance.
Regrettably, GBT was not internationally known since the most publications of this theory were written in German, especially in the first years. Only in recent years, GBT has gradually become a fertile research topic, with developments from linear to non-linear analysis.
Another reason for the misuse of GBT is the isolated application of the theory. Although recently researches apply finite element method to solve the GBT's problems numerically, the coupling between finite elements of GBT and other theories (shell, solid, etc) is not the subject of previous research. Thus, the main goal of this dissertation is the coupling between GBT and shell/membrane elements. Consequently, one achieves the benefits of both sides: the versatility of shell elements with the high performance of GBT elements.
Based on the assumptions of GBT, this dissertation presents how the separation of variables leads to two calculation's domains of a beam structure: a cross-section modal analysis and the longitudinal amplification axis. Therefore, there is the possibility of applying the finite element method not only in the cross-section analysis, but also the development for an exact GBT's finite element in the longitudinal direction.
For the cross-section analysis, this dissertation presents the solution of the quadratic eigenvalue problem with an original separation between plate and membrane mechanism. Subsequently, one obtains a clearer representation of the deformation mode, as well as a reduced quadratic eigenvalue problem.
Concerning the longitudinal direction, this dissertation develops the novel exact elements, based on hyperbolic and trigonometric shape functions. Although these functions do not have trivial expressions, they provide a recursive procedure that allows periodic derivatives to systematise the development of stiffness matrices. Also, these shape functions enable a single-element discretisation of the beam structure and ensure a smooth stress field.
From these developments, this dissertation achieves the formulation of its primary objective: the connection of GBT and shell elements in a mixed model. Based on the displacement field, it is possible to define the coupling equations applied in the master-slave method. Therefore, one can model the structural connections and joints with finite shell elements and the structural beams and columns with GBT finite element.
As a side effect, the coupling equations limit the displacement field of the shell elements under the assumptions of GBT, in particular in the neighbourhood of the coupling cross-section.
Although these side effects are almost unnoticeable in linear analysis, they lead to cumulative errors in non-linear analysis. Therefore, this thesis finishes with the evaluation of the mixed GBT-shell models in non-linear analysis.
Ohne das fast achtzigjährige Wirken des Allgemeinen Deutschen Musikvereins (ADMV) würde das deutsche Musikleben in seiner heutigen Form nicht existieren. Die kritische Edition Die Musikfeste des Allgemeinen Deutschen Musikvereins von 1859 bis 1937 (Eine Dokumentation der Veranstaltungen), herausgegeben von Jan Neubauer und Thomas Radecke, erschließt bereits erstmals grundlegende Quellen der Programme zu seinen nahezu jährlich anderen Orts veranstalteten Musikfesten und ist ebenfalls hier online abrufbar. Diese Datenbasis vertieft für den Zeitraum von vier deutschen Systemen den Diskurs über Probleme der Repertoirebildung, Institutionalisierung, Kommerzialisierung und Mediation von Musik.
1861 als erster überregionaler deutscher Musikverein mit dem offiziellen Ziel der Integration musikalisch gegensätzlicher zeitgenössischer Richtungen und künstlerischen Nachwuchsförderung konstituiert, trat der ADMV einerseits kosmopolitisch auf, und seine Musikfeste entwickelten sich zu einem Forum für internationale zeitgenössische Musik wie einem Podium für die Wiederentdeckung älterer Musik. Hier erlebten Werke von Richard Strauss, Gustav Mahler und Arnold Schönberg frühe, vielbeachtete Aufführungen. Anderseits reiften parallel dazu protonationalistische Tendenzen zu einem Nationalismus heran, der die Musikfeste 1938 nahtlos in die nationalsozialistischen Reichsmusiktage überführen konnte.
Mit dem zur Mitte des 19. Jahrhunderts ausgebrochenen Parteienstreit der Konservativen um Brahms mit der Neudeutschen Schule Liszts und Wagners trat mit der Institutionalisierung der letzteren im ADMV ein bis heute singuläres nationales Musikfestkonzept auf den Plan, das von Anbeginn medial gestützt war: die Tonkünstler-Versammlungen. Vor Ort berichteten neudeutsche Autoren pro domo für das Vereinsorgan Neue Zeitschrift für Musik, was von Rezensenten der konservativen Musikpresse scharf konterkariert wurde und so ein allseitig umfassendes Bild dieser musikalischen Novitätenmessen in ihrem stetigen Wandel abgibt.
Diese Publikation ist im von der Deutschen Forschungsgemeinschaft geförderten Projekt Der Allgemeine Deutsche Musikverein (ADMV, 1861–1937) – ein internationales Forum der Musik in Deutschlands Mitte am Gemeinsamen Institut für Musikwissenschaft Weimar-Jena der Hochschule für Musik FRANZ LISZT und der Friedrich-Schiller-Universität entstanden.
Natural Urban Resilience: Understanding general urban resilience through Addis Ababa’s inner city
(2021)
This dissertation describes the urban actors and spatial practices that contribute to natural urban resilience in Addis Ababa’s inner city. Natural urban resilience is a non-strategical and bottom-up, everyday form of general urban resilience – an urban system’s ability to maintain its essential characteristics under any change. This study gains significance by exposing conceptual gaps in the current un-derstanding of general urban resilience and highlighting its unconvincing applicability to African cities. This study attains further relevance by highlighting the danger of the ongoing large-scale redevelopment of the inner city. The inner city has naturally formed, and its urban memory, spaces, and social cohesion contribute to its primarily low-income population’s resilience. This thesis argues that the inner city’s demolition poses an incalculable risk of maladaptation to future stresses and shocks for Addis Ababa. The city needs a balanced urban discourse that highlights the inner city’s qualities and suggests feasible urban transformation measures. “Natural Urban Resilience” contributes an empirical study to the debate by identifying those aspects of the inner city that contribute to general resilience and identifies feasible action areas. This study develops a qualitative research design for a single case study in Addis Ababa. The data is obtained through expert interviews, interviews with resi-dents, and the analysis of street scene photos, which are abstracted using Grounded Theory. That way, this thesis provides first-time knowledge about who and what generates urban resilience in the inner city of Addis Ababa and how. Furthermore, the study complements existing theories on general urban resilience. It provides a detailed understanding of the change mechanisms in resilience, of which it identifies four: adaptation, upgrading, mitigation, and resistance. It also adapts the adaptive cycle, a widely used concept in resilience thinking, conceptually for urban environments. The study concludes that the inner city’s continued redevelopment poses an incalculable threat to the entire city. Therefore, “Natural urban resilience” recommends carefully weighing any intervention in the inner city to promote Addis Ababa’s overall resilience. This dissertation proposes a pattern language for natural urban resilience to support these efforts and to translate the model of natural urban resilience into practice.
Housing estates were fundamentally conceived upon state socialist utopia ideas to provide standard housing for citizens. While former state socialist housing estates have been extensively researched in the field of architecture, urban and sociology studies, there is still a gap in identifying how production processes affect morphological changes during the post-socialist era. This thesis compares the processes in the production of the largest housing estates of Marzahn in GDR and Petržalka in Czechoslovakia from 1970 to 1989 through contextual analysis of primary and secondary sources, which include visual maps, diagrams from professional architecture and planning journals, government documents and textbooks, as well as academic journals, books and newspaper articles. Then it discusses how these processes inadvertently created conducive conditions affecting their development in the market economy after 1989. It then interprets the results through application of Actor-Network Theory and Historical Institutionalism, while conceptualising them through David Harvey’s dialectical utopianism theory. Harvey (2000) delineates two types of utopia, one of spatial form and one of process. The former refers to materialised ideals in physical forms whereas the latter refers to the ongoing process of spatializing. The thesis aims to show how the production of Marzahn in GDR was more path dependent on policies established in 1950s and 1960s whereas Petržalka was a product of new Czechoslovakian policies in 1970s, changing aspects of the urban planning process, a manifestation of a more emphatic technocratic thinking on a wider scale. This ultimately influences the trajectories of development after 1989, showing more effects in Petržalka.
The development of a hydro-mechanically coupled Coupled-Eulerian–Lagrangian (CEL) method and its application to the back-analysisof vibratory pile driving model tests in water-saturated sand is presented. The predicted pile penetration using this approachis in good agreement with the results of the model tests as well as with fully Lagrangian simulations. In terms of pore water pressure, however, the results of the CEL simulation show a slightly worse accordance with the model tests compared to the Lagrangian simulation. Some shortcomings of the hydro-mechanically coupled CEL method in case of frictional contact problems and pore fluids with high bulk modulus are discussed. Lastly, the CEL method is applied to the simulation of vibratory driving of open-profile piles under partially drained conditions to study installation-induced changes in the soil state. It is concluded that the proposed method is capable of realistically reproducing the most important mechanisms in the soil during the driving process despite its addressed shortcomings.
Collecting Loss
(2021)
Wer sich mit "Identität" und "Erbe" befasst, also mit dem Zusammenhang zwischen der Konstituierung und Stabilität von Gemeinwesen und dem Bewahren von Gütern, Orten und Überlieferungen, kommt nicht umhin, sich auch mit Verlusten zu befassen. Verlust bezeichnet hier nicht die Abwesenheit eines Gutes, das Erbe war oder hätte werden können, sondern die soziale Beziehung zu dem verlorenen Gut und zu den Umständen seines Verlorengehens oder auch den Versuchen, es wiederzugewinnen.
Transformation of the Environment: Influence of “Urban Reagents.” German and Russian Case Studies
(2021)
An urban regeneration manifests itself through urban objects operating as change agents. The en-tailed diverse effects on the surroundings demonstrate experimental origin - an experiment as a preplanned but unpredictable method. An understanding of influences and features of urban ob-jects requires scrutiny due to a high potential of the elements to force an alteration and reactions. This dissertation explores the transformation of the milieu and mechanisms of this transformation.
Klangwelten gestalten. Zur Aktualität des Bauhauses in Sound Design und auditiver Stadtplanung
(2021)
Die Gestaltung von Klangwelten ist in den letzten Jahrzehnten in den Fokus von Stadtplanern und Architekten, Produkt-Designern und Musikproduzenten, aber auch der historischen und kulturwissenschaftlichen Forschung gerückt. Der Tagungsband versteht sich als ein Beitrag zu diesem neuen Praxis- und Forschungsfeld. Er will zugleich Bezugspunkte zu Konzepten des Bauhauses als einem historischen Vorläufer aufzeigen.
This dissertation investigates the interactions between urban form, allocation of activities, and pedestrian movement in the context of urban planning. The ability to assess the long-term impact of urban planning decisions on what people do and how they get there is of central importance, with various disciplines addressing this topic. This study focuses on approaches proposed by urban morphologists, urban economists, and transportation planners, each aiming the attention at a different part of the form-activity-movement interaction. Even though there is no doubt about the advantages of these highly focused approaches, it remains unclear what is the cost of ignoring the effect of some interactions while considering others. The general aim of this dissertation is to empirically test the validity of the individual models and quantify the impact of this isolationist approach on their precision and bias.
For this purpose, we propose a joined form-activity-movement interaction model and conduct an empirical study in Weimar, Germany. We estimate how the urban form and activities affect movement as well as how movement and urban form affect activities. By estimating these effects in isolation and simultaneously, we assess the bias of the individual models.
On the one hand, the empirical study results confirm the significance of all interactions suggested by the individual models. On the other hand, we were able to show that when these interactions are estimated in isolation, the resulting predictions are biased. To conclude, we do not question the knowledge brought by transportation planners, urban morphologists, and urban economists. However, we argue that it might be of little use on its own.
We see the relevance of this study as being twofold. On the one hand, we proposed a novel methodological framework for the simultaneous estimation of the form-activity-movement interactions. On the other hand, we provide empirical evidence about the strengths and limitations of current approaches.
One of the most important subjects of hydraulic engineering is the reliable estimation of the transverse distribution in the rectangular channel of bed and wall shear stresses. This study makes use of the Tsallis entropy, genetic programming (GP) and adaptive neuro-fuzzy inference system (ANFIS) methods to assess the shear stress distribution (SSD) in the rectangular channel.
To evaluate the results of the Tsallis entropy, GP and ANFIS models, laboratory observations were used in which shear stress was measured using an optimized Preston tube. This is then used to measure the SSD in various aspect ratios in the rectangular channel. To investigate the shear stress percentage, 10 data series with a total of 112 different data for were used. The results of the sensitivity analysis show that the most influential parameter for the SSD in smooth rectangular channel is the dimensionless parameter B/H, Where the transverse coordinate is B, and the flow depth is H. With the parameters (b/B), (B/H) for the bed and (z/H), (B/H) for the wall as inputs, the modeling of the GP was better than the other one. Based on the analysis, it can be concluded that the use of GP and ANFIS algorithms is more effective in estimating shear stress in smooth rectangular channels than the Tsallis entropy-based equations.
This study proposes an efficient Bayesian, frequency-based damage identification approach to identify damages in cantilever structures with an acceptable error rate, even at high noise levels. The catenary poles of electric high-speed train systems were selected as a realistic case study to cover the objectives of this study. Compared to other frequency-based damage detection approaches described in the literature, the proposed approach is efficiently able to detect damages in cantilever structures to higher levels of damage detection, namely identifying both the damage location and severity using a low-cost structural health monitoring (SHM) system with a limited number of sensors; for example, accelerometers. The integration of Bayesian inference, as a stochastic framework, in the proposed approach, makes it possible to utilize the benefit of data fusion in merging the informative data from multiple damage features, which increases the quality and accuracy of the results. The findings provide the decision-maker with the information required to manage the maintenance, repair, or replacement procedures.
Stadtpolitik für alle
(2021)
Die Corona-Krise hat die Erosion städtischer Solidarität offen zu Tage treten lassen. Dagegen bringen Anton Brokow-Loga und Frank Eckardt in dieser Schrift die praktische Utopie einer solidarischen Postwachstumsstadt „auf den Punkt“.
Vom Commoning über die Umverteilung der städtischen Flächen bis zu einer sozial-ökologischen Verkehrswende: Eine progressive Stadtpolitik für alle überwindet bisheriges Schubladendenken. Sie setzt stattdessen auf heterogene Zusammenhänge und ungewöhnliche Bündnisse. Zu dem hier umrissenen Vorhaben gehört auch, eine basisdemokratisch orientierte Stadtpolitik mit dem Ziel einer umfassenden Transformation von Stadt und Gesellschaft zu verknüpfen.
Wie kann ein Blick auf die kommunale Ebene helfen, globalen Ungerechtigkeiten zu begegnen? Welchen Weg weisen munizipalistische Plattformen und Vergemeinschaftungen jenseits von Privat- oder Staatseigentum?
Im Südwesten Weimars befindet sich ein leerstehender Gebäudekomplex, der im Stadtraum heute unter dem Namen Funkhaus und vor allem für studentisch organisierte Partys bekannt ist. Doch das Gebäude entstand ursprünglich nicht als Radiostation, sondern zwischen 1937 und 1944 als Prestigeprojekt des nationalsozialistisch zugespitzten Nietzsche-Kults. Diese Projektarbeit beleuchtet anhand von Archivalien und Expertinneninterviews die Nutzungsgeschichte der ehemaligen »Nietzsche-Gedächtnishalle« und wirft die Frage auf, ob und wie ein solcher NS-Bau als Partylocation genutzt werden kann.
Die Arbeit leistet einen wissenschaftlichen Beitrag zur Erforschung der Einsatzmöglichkeiten eines Immobilienportfoliomanagements für öffentliche museale Schlösserverwaltungen in Deutschland. Insbesondere wird ein für deren Organisation spezifisches Modell zur Investitionssteuerung herausgearbeitet und dessen Anwendbarkeit in der Praxis mit Experten diskutiert.
Die Haltungen des Architekten Luigi Snozzi. Untersucht am Beispiel des Projektes Monte Carasso
(2021)
Welche Haltung spricht aus den Werken von Architekt*innen? Lassen sich Werte und Handlungsanweisungen von Mauern und Plänen ablesen? Luigi Snozzis Entwürfe für Monte Carasso werden in dieser Arbeit exemplarisch darauf untersucht. Sie zeugen von der Verantwortung, die jede*r Architekt*in für das Umfeld hat, in dem sie oder er baut.
In vielen Leichtbauanwendungen ist der begrenzende Faktor die Schwingungsanfälligkeit der Bauteile. Eine Möglichkeit der Begrenzung von Schwingungsamplituden ist der gezielte Einsatz von Reibungsdämpfung in Leichtbaustrukturen. In dieser Arbeit wird der Einfluss dieser Art von Energiedissipation auf Leichtmetallstrukturen sowie topologieoptimierte Bauteil untersucht. Betrachtet werden dabei die Positionierung, Dimensionierung sowie die Reibeigenschaften dissipativer Elemente.
Corviale en dérive
(2021)
Im ersten Working Paper des Forschungsprojekts „Städtische Ko-Produktion von Teilhabe und Gemeinwohl. Aushandlungsprozesse zwischen zivilgesellschaft lichen Akteuren und kommunalen Verwaltungen“ möchten wir die von uns verwendeten zentralen Begrifflichkeiten definieren sowie einige Grundannahmen erläutern. Im Anschluss an Definitionen der Begriff e Wohlfahrtsregime, Teilhabe, Gemeinwohl, Governance, Zivilgesellschaft und soziale Bewegungen erfolgt eine Analyse der heutigen Krise von Teilhabe, die wir als Ausgangspunkt zur Untersuchung unserer Fallstudien definieren.
Das Working Paper dient sowohl der internen Selbstverständigung im Projekt als auch dem Austausch mit anderen Forschenden in der Förderlinie „Teilhabe und Gemeinwohl“ des Bundesministeriums für Bildung und Forschung (BMBF) sowie darüber hinaus mit Projekten, die sich ähnlichen Themen widmen.
Biofeedback constitutes a well-established, non-invasive method to voluntary interfere in emotional processing by means of cognitive strategies. However, treatment durations exhibit strong inter-individual variations and first successes can often be achieved only after a large number of sessions. Sham feedback constitutes a rather untapped approach by providing feedback that does not correspond to the participant’s actual state. The current study aims to gain insights into mechanisms of sham feedback processing in order to support new techniques in biofeedback therapy. We carried out two experiments and applied different types of sham feedback on skin conductance responses and pupil size changes during affective processing. Results indicate that standardized but context-sensitive sham signals based on skin conductance responses exert a stronger influence on emotional regulation compared to individual sham feedback from ongoing pupil dynamics. Also, sham feedback should forego unnatural signal behavior to avoid irritation and skepticism among participants. Altogether, a reasonable combination of stimulus features and sham feedback characteristics enables to considerably reduce the actual bodily responsiveness already within a single session.
Als Frühform des Tourismus war die Sommerfrische ab Mitte des 19. Jahrhunderts eng mit der flächendeckenden Verstädterung in Mitteleuropa und der Herausbildung eines urbanen Bürgertums verknüpft. Nachdem sich der Begriff in der zweiten Hälfte des 20. Jahrhunderts im Sprachgebrauch verlor, erfährt er gegenwärtig - auch im Zuge einer neuen positiven Konnotation des Ländlichen - eine Art Renaissance. Im Schwarzatal als einer historischen Zielregion dieser Reisepraxis arbeitet der lokale Verein Zukunftswerkstatt Schwarzatal gemeinsam mit der IBA Thüringen an einer zeitgenössischen Form der Sommerfrische, die auch Antworten auf den tiefgreifenden Strukturwandel nach 1989 geben soll.
Die Arbeit thematisiert die programmatische Renaissance der Sommerfrische im Schwarzatal und stellt sie dem historischen Phänomen der Sommerfrische des 19. und 20. Jahrhunderts unter den drei Forschungsfragen gegenüber. Die Forschungsfragen nehmen Bezug auf die soziale, die materielle sowie die symbolische Dimension der Raumkonstitution beider Sommerfrischen, indem nach den jeweiligen Akteuren, den Regeln der physischen Umgestaltung sowie den hegemonialen Vorstellungen über die Zielorte gefragt wird. Die Arbeit ordnet sich entsprechend in eine sozialkonstruktivistische Geographie des Ländlichen ein. Sie gibt schließlich Auskunft darüber, warum es sich bei der Sommerfrische Schwarzatal um eine regional selbstbestimmte Form der Sommerfrische handelt.
Schlagworte wir Kooperation, Koproduktion und Kollaboration sind in Planungswissenschaften und Architektur schwer in Mode. Selten wird allerdings dargelegt, was diese Art(en) der Zusammenarbeit zwischen zivilgesellschaftlichen Akteuren auf der einen Seite und staatlichen Akteuren aus Politik und Verwaltung auf der anderen Seite von gewöhnlichen Formen der Partizipation und Bürger_innenbeteiligung unterscheidet. Anders im Buch von Michael Ziehl: Ihm gelingt es, anhand eines Fallbeispiels die intensive Zusammenarbeit zwischen Aktivist_innen rund ums Hamburger Gängeviertel und verschiedenen städtischen Institutionen detailliert nachzuzeichnen und damit den qualitativen Unterschied zwischen Kooperation und Beteiligung nachvollziehbar zu machen.
Die Zukunft war jetzt
(2021)
Die US-amerikanische Kulturanthropologin Christina Schwenkel legt mit Building socialism eine quellengesättigte ethnografische Studie über Zerstörung, Wiederaufbau und Nutzungsperspektiven der vietnamesischen Stadt Vinh vor. Ein besonderes Augenmerk liegt auf den agencies der Beteiligten. Im Zentrum der Untersuchung steht ein Quartier, dessen Wohnblocks mit materieller und ideeller Unterstützung der DDR errichtet wurden. Nicht nur sind die methodischen Zugänge der Untersuchung vielversprechend und gewinnbringend – angesichts des drohenden Stadtumbaus, der für die Bewohner:innen des Quartiers Quang Trung Abriss und Verdrängung bedeuten würde, gewinnt ihre städtebauhistorische Ethnografie auch an politischer Relevanz.
As machine vision-based inspection methods in the field of Structural Health Monitoring (SHM) continue to advance, the need for integrating resulting inspection and maintenance data into a centralised building information model for structures notably grows. Consequently, the modelling of found damages based on those images in a streamlined automated manner becomes increasingly important, not just for saving time and money spent on updating the model to include the latest information gathered through each inspection, but also to easily visualise them, provide all stakeholders involved with a comprehensive digital representation containing all the necessary information to fully understand the structure’s current condition, keep track of any progressing deterioration, estimate the reduced load bearing capacity of the damaged element in the model or simulate the propagation of cracks to make well-informed decisions interactively and facilitate maintenance actions that optimally extend the service life of the structure. Though significant progress has been recently made in information modelling of damages, the current devised methods for the geometrical modelling approach are cumbersome and time consuming to implement in a full-scale model. For crack damages, an approach for a feasible automated image-based modelling is proposed utilising neural networks, classical computer vision and computational geometry techniques with the aim of creating valid shapes to be introduced into the information model, including related semantic properties and attributes from inspection data (e.g., width, depth, length, date, etc.). The creation of such models opens the door for further possible uses ranging from more accurate structural analysis possibilities to simulation of damage propagation in model elements, estimating deterioration rates and allows for better documentation, data sharing, and realistic visualisation of damages in a 3D model.
Die Auswirkungen der durch den Kapitalismus befeuerten Umweltzerstörung werden immer deutlicher erkennbar. Unsere Gesellschaft ist nun damit konfrontiert, dass ihre kulturelle Identität, aber auch ihr Wohlstand sowohl eng mit Konsum und Wirtschaftswachstum als auch mit der Gesundheit der Natur verbunden sind. Es scheint ein geeigneter Moment, um die Perspektive zu wechseln und einer neuen Form des Wachstums eine Chance zu geben. Pilze sind eine von der Region unabhängige, natürlich vorkommende Ressource, die lokal angebaut und verarbeitet werden kann, ohne die Umwelt zu belasten. Pilze sind klimafreundlich, müllvermeidend und in bestehende natürliche Kreisläufe inkludierbar. Kurzum, Pilze sind cool, doch das wissen nicht Viele. Das sollte sich ändern. Mit Myzelwachstum gegen das Wachstumsparadigma.
In kalten und gemäßigten Klimazonen kann Beton einem kombinierten Frost-Tausalz-Angriff ausgesetzt sein, der zu Schäden in Form von Abwitterungen führen kann. Daher wurden zahlreiche Prüfverfahren entwickelt, um die Widerstandsfähigkeit von Betonzusammensetzungen gegen diese Art des Angriffs zu bestimmen. Diese Tests simulieren in der Regel einen starken Angriff mit hohen Sättigungsgraden, wie z. B. bei Betonfahrbahnen. Es gibt nur sehr wenige Ansätze für die Prüfung des Widerstands von Betonen, die nur einem mittleren Sättigungsgrad ausgesetzt sind, da solche Betonelemente in der Regel keine nennenswerten Abwitterungen aufweisen. Die zunehmende Verwendung von klinkereffizienten Zementen könnte sich jedoch in gewissem Maße auf den Frost-Tausalz-Widerstand solcher Betonelemente auswirken. Um eine angemessene Dauerhaftigkeit zu gewährleisten ist es daher wünschenswert, ihre Leistungsfähigkeit in einem tatsächlichen Prüfverfahren zu ermitteln, anstatt sich auf Erfahrungswerte zu verlassen. Daher wurden Ansätze für abgeschwächte Prüfverfahren entwickelt, die auf dem Slab-Test bzw. dem CDF-Test beruhen.
Ohne das fast achtzigjährige Wirken des Allgemeinen Deutschen Musikvereins (ADMV) würde das deutsche Musikleben in seiner heutigen Form nicht existieren. Die Dokumentation der Programme zu seinen von 1859 bis 1937 nahezu jährlich anderen Orts veranstalteten Musikfesten erschließt erstmals grundlegende Quellen hierzu. Diese Datenbasis vertieft für den Zeitraum von vier deutschen Systemen den Diskurs über Probleme der Repertoirebildung, Institutionalisierung, Kommerzialisierung und Mediation von Musik.
1861 als erster überregionaler deutscher Musikverein mit dem offiziellen Ziel der Integration musikalisch gegensätzlicher zeitgenössischer Richtungen und künstlerischen Nachwuchsförderung konstituiert, trat der ADMV einerseits kosmopolitisch auf, und seine Musikfeste entwickelten sich zu einem Forum für internationale zeitgenössische Musik wie einem Podium für die Wiederentdeckung älterer Musik. Hier erlebten Werke von Richard Strauss, Gustav Mahler und Arnold Schönberg frühe, vielbeachtete Aufführungen. Anderseits reiften parallel dazu protonationalistische Tendenzen zu einem Nationalismus heran, der die Musikfeste 1938 nahtlos in die nationalsozialistischen Reichsmusiktage überführen konnte.
Nach zahlreichen Standortwechseln sind die nunmehr restaurierten Materialien der einstigen Vereinsbibliothek und Vereinsakten im Hochschularchiv / Thüringischen Landesmusikarchiv Weimar sowie Goethe- und Schiller-Archiv Weimar wieder zugänglich. So wird jetzt eine erste kritische Edition der Festprogramme angeboten, in welcher die Programmfolge zu jeder Aufführung mit Werkangaben und dem Nachweis der Aufführenden prozessual von der Planung bis zur Präzisierung und Ergänzung bzw. Modifizierung rekonstruiert wurde. Darüber hinaus werden alle wissenschaftlichen Vorträge, Haupt- u. a. Versammlungen, Beratungen und die gesamten Personalia des Vereins und der jeweiligen Lokalkomitees dokumentiert sowie lassen sich Komponisten und Interpreten über Indizes erschließen.
Diese Publikation ist im von der Deutschen Forschungsgemeinschaft geförderten Projekt Der Allgemeine Deutsche Musikverein (ADMV, 1861–1937) – ein internationales Forum der Musik in Deutschlands Mitte am Gemeinsamen Institut für Musikwissenschaft Weimar-Jena der Hochschule für Musik FRANZ LISZT und der Friedrich-Schiller-Universität entstanden.
Accurate prediction of stable alluvial hydraulic geometry, in which erosion and sedimentation are in equilibrium, is one of the most difficult but critical topics in the field of river engineering. Data mining algorithms have been gaining more attention in this field due to their high performance and flexibility. However, an understanding of
the potential for these algorithms to provide fast, cheap, and accurate predictions of hydraulic geometry is lacking. This study provides the first quantification of this potential. Using at-a-station field data, predictions of flow depth, water-surface width and longitudinal water surface slope are made using three standalone data mining techniques -, Instance-based Learning (IBK), KStar, Locally Weighted Learning (LWL) - along with four types of novel hybrid algorithms in which the standalone models are trained with Vote, Attribute Selected
Classifier (ASC), Regression by Discretization (RBD), and Cross-validation Parameter Selection (CVPS) algorithms (Vote-IBK, Vote-Kstar, Vote-LWL, ASC-IBK, ASC-Kstar, ASC-LWL, RBD-IBK, RBD-Kstar, RBD-LWL, CVPSIBK, CVPS-Kstar, CVPS-LWL). Through a comparison of their predictive performance and a sensitivity analysis of the driving variables, the results reveal: (1) Shield stress was the most effective parameter in the prediction of all geometry dimensions; (2) hybrid models had a higher prediction power than standalone data mining models,
empirical equations and traditional machine learning algorithms; (3) Vote-Kstar model had the highest performance in predicting depth and width, and ASC-Kstar in estimating slope, each providing very good prediction performance. Through these algorithms, the hydraulic geometry of any river can potentially be predicted accurately and with ease using just a few, readily available flow and channel parameters. Thus, the results reveal that these models have great potential for use in stable channel design in data poor catchments, especially in developing nations where technical modelling skills and understanding of the hydraulic and sediment processes occurring in the river system may be lacking.
The concept of information entropy together with the principle of maximum entropy to open channel flow is essentially based on some physical consideration of the problem under consideration. This paper is a discussion on Yeganeh and Heidari (2020)’s paper, who proposed a new approach for measuring vertical distribution of streamwise velocity in open channels. The discussers argue that their approach is conceptually incorrect and thus leads to a physically unrealistic situation. In addition, the discussers found some wrong mathematical expressions (which are assumed to be typos) written in the paper, and also point out that the authors did not cite some of the original papers on the topic.
Complex vortex flow patterns around bridge piers, especially during floods, cause scour process that can result in the failure of foundations. Abutment scour is a complex three-dimensional phenomenon that is difficult to predict especially with traditional formulas obtained using empirical approaches such as regressions. This paper presents a test of a standalone Kstar model with five novel hybrid algorithm of bagging (BA-Kstar), dagging (DA-Kstar), random committee (RC-Kstar), random subspace (RS-Kstar), and weighted instance handler wrapper (WIHWKstar) to predict scour depth (ds) for clear water condition. The dataset consists of 99 scour depth data from flume experiments (Dey and Barbhuiya, 2005) using abutment shapes such as vertical, semicircular and 45◦ wing. Four dimensionless parameter of relative flow depth (h/l), excess abutment Froude number (Fe), relative sediment size (d50/l) and relative submergence (d50/h) were considered for the prediction of relative scour depth (ds/l). A portion of the dataset was used for the calibration (70%), and the remaining used for model validation. Pearson correlation coefficients helped deciding relevance of the input parameters combination and finally four different combinations of input parameters were used. The performance of the models was assessed visually and with quantitative metrics. Overall, the best input combination for vertical abutment shape is the combination of Fe, d50/l and h/l, while for semicircular and 45◦ wing the combination of the Fe and d50/l is the most effective input parameter combination. Our results show that incorporating Fe, d50/l and h/l lead to higher performance while involving d50/h reduced the models prediction power for vertical abutment shape and for semicircular and 45◦ wing involving h/l and d50/h lead to more error. The WIHW-Kstar provided the highest performance in scour depth prediction around vertical abutment shape while RC-Kstar model outperform of other models for scour depth prediction around semicircular and 45◦ wing.