@unpublished{EngelmannSchwendnerSeim, author = {Engelmann, Iris and Schwendner, Sascha and Seim, Werner}, title = {Materialsparende Nagelbinder - Aspekte der Konstruktionsgeschichte von 1930 bis 1990}, doi = {10.25643/bauhaus-universitaet.4888}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20230112-48882}, pages = {33}, abstract = {Materialsparende Holzkonstruktionen, die insbesondere w{\"a}hrend der Kriegs- und Nachkriegszeit im 20. Jahrhundert entwickelt und optimiert wurden, erlangen aktuell aus konstruktionshistorischer Sicht, aber auch aus {\"o}konomischer Sicht erneut Interesse. Der vorliegende Beitrag gibt einen {\"U}berblick angefangen von den ersten Konstruktionen Ende der 1920er Jahre bis hin zu Typenbindern der DDR, die noch bis 1990 {\"u}ber Landwirtschaftsbauten errichtet wurden und heute oft als Tragkonstruktionen f{\"u}r Photovoltaikanlagen weiterverwendet werden. Der Fokus liegt auf der chronologischen Vorstellung ausgew{\"a}hlter Konstruktionsweisen f{\"u}r Hallen- und Hausd{\"a}cher unterschieden nach Fachwerk- und Vollwandbindern. Sowohl die verantwortlichen Ingenieure und deren Herkunft, sowie wesentliche Anwendungsfelder und Beispielbauten kommen in der {\"U}berblicksdarstellung zur Sprache. Eine wesentliche Erkenntnis ist die im Betrachtungszeitraum 1930 bis 1990 zu verzeichnende Reduzierung einer Vielzahl genagelter Spar- hin zu Typenkonstruktionen, die im wesentlichen {\"a}ußerst materialeffiziente Fachwerkbinder f{\"u}r Satteld{\"a}cher hervorbrachte.}, subject = {Ingenieurholzbau}, language = {de} } @unpublished{FischerSchwendnerSeimetal., author = {Fischer, Jens and Schwendner, Sascha and Seim, Werner and Engelmann, Iris}, title = {Verbindungen mit N{\"a}geln im Holzbau - Die Erforschung und Entwicklung von Konstruktionsregeln}, doi = {10.25643/bauhaus-universitaet.4889}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20230112-48893}, pages = {25}, abstract = {Der Nagel als tragendes Holzverbindungsmittel ist heute gut bekannt. Doch noch vor 100 Jahren war das anders: sein statisch konstruktiver Gebrauch war verboten. Das {\"a}nderte sich mit Beginn dessen Erforschung Ende der 1920er Jahre. Seit 1933 ist der Nagel Bestandteil der deutschen Regelwerke und findet seitdem breite Verwendung. {\"U}ber weite Teile des 20. Jahrhunderts diente er in Not- und Sparkonstruktionen wie Brett- und Bohlenbindern als hocheffizientes Verbindungsmittel der Wahl. Diese materialsparenden Tragwerke waren bei der periodisch im-mer wiederkehrenden Ressourcenknappheit sehr gefragt und sind ein wichtiger Bestandteil der Konstruktionsgeschichte des Holzbaus. In dem folgenden Beitrag wird die Erforschung des Na-geltragverhaltens und die einhergehende fortlaufende Normierung behandelt. Die Errungen-schaften einzelner Forschungsvorhaben werden vorgestellt. Anhand eines Zeitstrahls werden Zusammenh{\"a}nge zwischen Forschung und Normung gezeigt. Tabellen und Grafiken verdeutli-chen die {\"A}nderungen innerhalb der Normen von der ersten DIN 1052 im Jahr 1933 {\"u}ber die erste eigenst{\"a}ndige Holzbaunorm in der DDR, der TGL 112-0730, aus 1963 bis zur DIN 1052- 1988. Dabei wird immer Bezug zum derzeitigen Entwurf des Eurocode 5 genommen. Allgemein zeigt sich, dass ein Großteil der heutigen Kenntnisse immer noch auf die Grundlagenforschung der 1930er Jahre zur{\"u}ckgeht.}, subject = {Ingenieurholzbau}, language = {de} } @unpublished{SchwendnerFischerSeimetal., author = {Schwendner, Sascha and Fischer, Jens and Seim, Werner and Engelmann, Iris}, title = {N{\"a}gel im Holzbau - Die Erforschung des Trag- und Verformungsverhaltens}, doi = {10.25643/bauhaus-universitaet.4890}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20230112-48904}, pages = {18}, abstract = {Die Tragf{\"a}higkeit von N{\"a}geln und Nagelverbindungen im Holzbau war lange Zeit ausschließlich {\"u}ber Tabellen, die auf experimentellen Untersuchungen basierten, geregelt. In den letzten 100 Jahren untersuchten unterschiedliche Forscher das Last-Verformungsverhalten dieser Verbindungen und entwickelten Modelle, mit denen auf Grundlage von analytischen Gleichungen die Tragf{\"a}higkeit und das Verformungsverhalten von N{\"a}geln berechnet werden kann. Die zun{\"a}chst in Not- und Sparkonstruktion eingesetzten N{\"a}gel werden heutzutage vor allem bei Tafelelementen verwendet. Im Bestand finden sich aber auch zahlreiche, teils weit gespannte Fachwerkkonstruktionen. In dem folgenden Beitrag werden die Erforschung und Entwicklung der Tragf{\"a}higkeit sowie des Verformungsverhaltens von genagelten Verbindungen detailliert und strukturiert erl{\"a}utert. Die zugeh{\"o}rigen Meilensteine werden genauer betrachtet. {\"U}ber unterschiedliche Methoden f{\"u}r die Bestimmung der Tragf{\"a}higkeit sowie mechanische Ph{\"a}nomene, die erst nach und nach entdeckt wurden, k{\"o}nnen in der aktuellen Normung sehr individuelle Verbindungen nachgewiesen und deren Verhalten beschrieben werden. Tabellen und Grafiken verdeutlichen die einzelnen Meilensteine der geschichtlichen Entwicklung und vergleichen konkret die normativen Regelungen seit Beginn der Einf{\"u}hrung des Nagels in den Ingenieurholzbau in Deutschland. Hierbei kann gezeigt werden, dass einige Definitionen seit 1933 bis heute noch ihre G{\"u}ltigkeit behalten.}, subject = {Ingenieurholzbau}, language = {de} } @unpublished{SheikhKhozaniKumbhakar, author = {Sheikh Khozani, Zohreh and Kumbhakar, Manotosh}, title = {Discussion of "Estimation of one-dimensional velocity distribution by measuring velocity at two points" by Yeganeh and Heidari (2020)}, doi = {10.25643/bauhaus-universitaet.4366}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20210216-43663}, abstract = {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.}, subject = {Geschwindigkeit}, language = {en} } @unpublished{KhosraviSheikhKhozaniMao, author = {Khosravi, Khabat and Sheikh Khozani, Zohreh and Mao, Luka}, title = {A comparison between advanced hybrid machine learning algorithms and empirical equations applied to abutment scour depth prediction}, doi = {10.25643/bauhaus-universitaet.4388}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20210311-43889}, pages = {43}, abstract = {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.}, subject = {maschinelles Lernen}, language = {en} } @unpublished{KhosraviSheikhKhozaniCooper, author = {Khosravi, Khabat and Sheikh Khozani, Zohreh and Cooper, James R.}, title = {Predicting stable gravel-bed river hydraulic geometry: A test of novel, advanced, hybrid data mining algorithms}, volume = {2021}, doi = {10.25643/bauhaus-universitaet.4499}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20211004-44998}, abstract = {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.}, subject = {Maschinelles Lernen}, language = {en} } @unpublished{VogelVoelkerBodeetal., author = {Vogel, Albert and V{\"o}lker, Conrad and Bode, Matthias and Marx, Steffen}, title = {Messung und Simulation der Erw{\"a}rmung von erm{\"u}dungsbeanspruchten Betonprobek{\"o}rpern}, series = {Bauphysik}, volume = {2020}, journal = {Bauphysik}, number = {Volume 42, Issue 2}, publisher = {John Wiley and Sons}, doi = {10.25643/bauhaus-universitaet.4147}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20200425-41471}, pages = {86 -- 93}, abstract = {Im vorliegenden Beitrag werden Messungen und Berechnungen vorgestellt, die die Temperaturentwicklung in Betonzylindern aufgrund zyklischer Beanspruchung genau beschreiben. Die Messungen wurden in einem Versuchsstand, die Berechnungen im FEM-Programm ANSYS durchgef{\"u}hrt. Mit Hilfe der Temperaturmessungen konnten die Simulationen f{\"u}r die Temperaturentwicklung der Betonzylinder mit der verwendeten Betonrezeptur validiert werden. Die Untersuchungen lassen den Schluss zu, dass bei zyklischer Probek{\"o}rperbelastung und der einhergehenden Probek{\"o}rperdehnung Energie dissipiert wird und diese maßgeblich f{\"u}r die Erw{\"a}rmung der Probe verantwortlich ist.}, subject = {zyklische Beanspruchung}, language = {de} } @unpublished{VogelBenzVoelker, author = {Vogel, Albert and Benz, Alexander and V{\"o}lker, Conrad}, title = {Untersuchung des W{\"a}rme{\"u}bergangs von zyklisch beanspruchten Betonzylindern}, volume = {2020}, number = {Volume 42, Issue 3}, publisher = {John Wiley and Sons}, doi = {10.25643/bauhaus-universitaet.4181}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20200619-41813}, pages = {131 -- 138}, abstract = {Wiederkehrende Belastungen, wie sie beispielsweise an Br{\"u}cken oder Windenergieanlagen auftreten, k{\"o}nnen innerhalb der Nutzungsdauer solcher Bauwerke bis zu 1.000.000.000 Lastwechsel erreichen. Um das dadurch eintretende Erm{\"u}dungsverhalten von Beton zu untersuchen, werden diese zyklischen Beanspruchungen in mechanischen Versuchen mit Pr{\"u}fzylindern nachgestellt. Damit Versuche mit solch hohen Lastwechselzahlen in akzeptablen Zeitdauern durchgef{\"u}hrt werden k{\"o}nnen, wird die Belastungsfrequenz erh{\"o}ht. Als Folge dieser erh{\"o}hten Belas-tungsfrequenz erw{\"a}rmen sich allerdings die Betonprobek{\"o}rper, was zu einem fr{\"u}heren, unrealistischen Versagenszeitpunkt f{\"u}hren kann, weshalb die Erw{\"a}rmung begrenzt werden muss. Um die W{\"a}rmefreisetzung in der Probe zu untersuchen, wurden Versuche und Simulationen durchgef{\"u}hrt. Im Beitrag wird die analytische und messtechnische Analyse des W{\"a}rme{\"u}bergangs an erw{\"a}rmten Betonzylindern vorgestellt. Resultierend daraus wird eine M{\"o}glichkeit zur Reduktion der Erw{\"a}rmung an zyklisch beanspruchten Betonzylindern vorgestellt.}, subject = {Zyklische Beanspruchung}, language = {de} } @unpublished{AbbasKavrakovMorgenthaletal., author = {Abbas, Tajammal and Kavrakov, Igor and Morgenthal, Guido and Lahmer, Tom}, title = {Prediction of aeroelastic response of bridge decks using artificial neural networks}, doi = {10.25643/bauhaus-universitaet.4097}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20200225-40974}, abstract = {The assessment of wind-induced vibrations is considered vital for the design of long-span bridges. The aim of this research is to develop a methodological framework for robust and efficient prediction strategies for complex aerodynamic phenomena using hybrid models that employ numerical analyses as well as meta-models. Here, an approach to predict motion-induced aerodynamic forces is developed using artificial neural network (ANN). The ANN is implemented in the classical formulation and trained with a comprehensive dataset which is obtained from computational fluid dynamics forced vibration simulations. The input to the ANN is the response time histories of a bridge section, whereas the output is the motion-induced forces. The developed ANN has been tested for training and test data of different cross section geometries which provide promising predictions. The prediction is also performed for an ambient response input with multiple frequencies. Moreover, the trained ANN for aerodynamic forcing is coupled with the structural model to perform fully-coupled fluid--structure interaction analysis to determine the aeroelastic instability limit. The sensitivity of the ANN parameters to the model prediction quality and the efficiency has also been highlighted. The proposed methodology has wide application in the analysis and design of long-span bridges.}, subject = {Aerodynamik}, language = {en} } @unpublished{BodeMarxVogeletal., author = {Bode, Matthias and Marx, Steffen and Vogel, Albert and V{\"o}lker, Conrad}, title = {Dissipationsenergie bei Erm{\"u}dungsversuchen an Betonprobek{\"o}rpern}, volume = {2019}, doi = {10.25643/bauhaus-universitaet.4493}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20211012-44938}, pages = {9}, abstract = {Aufgrund des visko-elastoplastischen Materialverhaltens von Beton wird Probek{\"o}rpern und Bauteilen infolge zyklischer Beanspruchungen Energie zugef{\"u}hrt. Die entsprechenden Energiegr{\"o}ßen werden durch Hysteresefl{\"a}chen der Spannungs-Dehnungslinien beschrieben. In der Literatur finden sich dabei unterschiedliche Ans{\"a}tze, wof{\"u}r diese Energie verwendet wird. Erste Untersuchungen zeigen, dass zumindest ein Teil dieser dissipierten Energie in thermische Energie umgewandelt wird. Mithilfe der in diesem Beitrag beschriebenen Methodik lassen sich diese Energiegr{\"o}ßen f{\"u}r jeden Lastwechsel eines Erm{\"u}dungsversuches schnell und zuverl{\"a}ssig bestimmen. Anschließend wurden mit dem implementierten Algorithmus die dissipierten Energien von insgesamt 27 zyklischen Versuchen ausgewertet. Analog zu der Dehnungsentwicklung und der Steifigkeitsdegradation weisen auch die Verl{\"a}ufe der dissipierten Energie {\"u}ber die Lastwechselzahl einen dreiphasigen Verlauf auf. Die Auswertung zeigt außerdem eine Korrelation zwischen der Bruchlastwechselzahl und der dissipierten Energie. Auch der Zusammenhang zwischen Probek{\"o}rpererw{\"a}rmung und dissipierter Energie konnte best{\"a}tigt werden.}, subject = {Erm{\"u}dung}, language = {de} } @unpublished{KavrakovArgentiniOmarinietal., author = {Kavrakov, Igor and Argentini, Tommaso and Omarini, Simone and Rocchi, Daniele and Morgenthal, Guido}, title = {Determination of complex aerodynamic admittance of bridge decks under deterministic gusts using the Vortex Particle Method}, doi = {10.25643/bauhaus-universitaet.4088}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20200206-40883}, abstract = {Long-span bridges are prone to wind-induced vibrations. Therefore, a reliable representation of the aerodynamic forces acting on a bridge deck is of a major significance for the design of such structures. This paper presents a systematic study of the two-dimensional (2D) fluid-structure interaction of a bridge deck under smooth and turbulent wind conditions. Aerodynamic forces are modeled by two approaches: a computational fluid dynamics (CFD) model and six semi-analytical models. The vortex particle method is utilized for the CFD model and the free-stream turbulence is introduced by seeding vortex particles upstream of the deck with prescribed spectral characteristics. The employed semi-analytical models are based on the quasi-steady and linear unsteady assumptions and aerodynamic coefficients obtained from CFD analyses. The underlying assumptions of the semi-analytical aerodynamic models are used to interpret the results of buffeting forces and aeroelastic response due to a free-stream turbulence in comparison with the CFD model. Extensive discussions are provided to analyze the effect of linear fluid memory and quasi-steady nonlinearity from a CFD perspective. The outcome of the analyses indicates that the fluid memory is a governing effect in the buffeting forces and aeroelastic response, while the effect of the nonlinearity is overestimated by the quasi-steady models. Finally, flutter analyses are performed and the obtained critical velocities are further compared with wind tunnel results, followed by a brief examination of the post-flutter behavior. The results of this study provide a deeper understanding of the extent of which the applied models are able to replicate the physical processes for fluid-structure interaction phenomena in bridge aerodynamics and aeroelasticity.}, subject = {Bridge}, language = {en} } @unpublished{RadmardRahmaniKoenke, author = {Radmard Rahmani, Hamid and K{\"o}nke, Carsten}, title = {Passive Control of Tall Buildings Using Distributed Multiple Tuned Mass Dampers}, doi = {10.25643/bauhaus-universitaet.3859}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20190311-38597}, pages = {43}, abstract = {The vibration control of the tall building during earthquake excitations is a challenging task due to their complex seismic behavior. This paper investigates the optimum placement and properties of the Tuned Mass Dampers (TMDs) in tall buildings, which are employed to control the vibrations during earthquakes. An algorithm was developed to spend a limited mass either in a single TMD or in multiple TMDs and distribute them optimally over the height of the building. The Non-dominated Sorting Genetic Algorithm (NSGA - II) method was improved by adding multi-variant genetic operators and utilized to simultaneously study the optimum design parameters of the TMDs and the optimum placement. The results showed that under earthquake excitations with noticeable amplitude in higher modes, distributing TMDs over the height of the building is more effective in mitigating the vibrations compared to the use of a single TMD system. From the optimization, it was observed that the locations of the TMDs were related to the stories corresponding to the maximum modal displacements in the lower modes and the stories corresponding to the maximum modal displacements in the modes which were highly activated by the earthquake excitations. It was also noted that the frequency content of the earthquake has significant influence on the optimum location of the TMDs.}, subject = {Schwingungsd{\"a}mpfer}, language = {en} } @unpublished{SteinerBourinetLahmer, author = {Steiner, Maria and Bourinet, Jean-Marc and Lahmer, Tom}, title = {An adaptive sampling method for global sensitivity analysis based on least-squares support vector regression}, doi = {10.25643/BAUHAUS-UNIVERSITAET.3832}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20181218-38320}, pages = {1 -- 33}, abstract = {In the field of engineering, surrogate models are commonly used for approximating the behavior of a physical phenomenon in order to reduce the computational costs. Generally, a surrogate model is created based on a set of training data, where a typical method for the statistical design is the Latin hypercube sampling (LHS). Even though a space filling distribution of the training data is reached, the sampling process takes no information on the underlying behavior of the physical phenomenon into account and new data cannot be sampled in the same distribution if the approximation quality is not sufficient. Therefore, in this study we present a novel adaptive sampling method based on a specific surrogate model, the least-squares support vector regresson. The adaptive sampling method generates training data based on the uncertainty in local prognosis capabilities of the surrogate model - areas of higher uncertainty require more sample data. The approach offers a cost efficient calculation due to the properties of the least-squares support vector regression. The opportunities of the adaptive sampling method are proven in comparison with the LHS on different analytical examples. Furthermore, the adaptive sampling method is applied to the calculation of global sensitivity values according to Sobol, where it shows faster convergence than the LHS method. With the applications in this paper it is shown that the presented adaptive sampling method improves the estimation of global sensitivity values, hence reducing the overall computational costs visibly.}, subject = {Approximation}, language = {en} } @unpublished{RezakazemiMosaviShirazian, author = {Rezakazemi, Mashallah and Mosavi, Amir and Shirazian, Saeed}, title = {ANFIS pattern for molecular membranes separation optimization}, volume = {2018}, doi = {10.25643/BAUHAUS-UNIVERSITAET.3821}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20181122-38212}, pages = {1 -- 20}, abstract = {In this work, molecular separation of aqueous-organic was simulated by using combined soft computing-mechanistic approaches. The considered separation system was a microporous membrane contactor for separation of benzoic acid from water by contacting with an organic phase containing extractor molecules. Indeed, extractive separation is carried out using membrane technology where complex of solute-organic is formed at the interface. The main focus was to develop a simulation methodology for prediction of concentration distribution of solute (benzoic acid) in the feed side of the membrane system, as the removal efficiency of the system is determined by concentration distribution of the solute in the feed channel. The pattern of Adaptive Neuro-Fuzzy Inference System (ANFIS) was optimized by finding the optimum membership function, learning percentage, and a number of rules. The ANFIS was trained using the extracted data from the CFD simulation of the membrane system. The comparisons between the predicted concentration distribution by ANFIS and CFD data revealed that the optimized ANFIS pattern can be used as a predictive tool for simulation of the process. The R2 of higher than 0.99 was obtained for the optimized ANFIS model. The main privilege of the developed methodology is its very low computational time for simulation of the system and can be used as a rigorous simulation tool for understanding and design of membrane-based systems. Highlights are, Molecular separation using microporous membranes. Developing hybrid model based on ANFIS-CFD for the separation process, Optimization of ANFIS structure for prediction of separation process}, subject = {Fluid}, language = {en} } @unpublished{KavrakovMorgenthal, author = {Kavrakov, Igor and Morgenthal, Guido}, title = {A synergistic study of a CFD and semi-analytical models for aeroelastic analysis of bridges in turbulent wind conditions}, doi = {10.25643/bauhaus-universitaet.4087}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20200206-40873}, abstract = {Long-span bridges are prone to wind-induced vibrations. Therefore, a reliable representation of the aerodynamic forces acting on a bridge deck is of a major significance for the design of such structures. This paper presents a systematic study of the two-dimensional (2D) fluid-structure interaction of a bridge deck under smooth and turbulent wind conditions. Aerodynamic forces are modeled by two approaches: a computational fluid dynamics (CFD) model and six semi-analytical models. The vortex particle method is utilized for the CFD model and the free-stream turbulence is introduced by seeding vortex particles upstream of the deck with prescribed spectral characteristics. The employed semi-analytical models are based on the quasi-steady and linear unsteady assumptions and aerodynamic coefficients obtained from CFD analyses. The underlying assumptions of the semi-analytical aerodynamic models are used to interpret the results of buffeting forces and aeroelastic response due to a free-stream turbulence in comparison with the CFD model. Extensive discussions are provided to analyze the effect of linear fluid memory and quasi-steady nonlinearity from a CFD perspective. The outcome of the analyses indicates that the fluid memory is a governing effect in the buffeting forces and aeroelastic response, while the effect of the nonlinearity is overestimated by the quasi-steady models. Finally, flutter analyses are performed and the obtained critical velocities are further compared with wind tunnel results, followed by a brief examination of the post-flutter behavior. The results of this study provide a deeper understanding of the extent of which the applied models are able to replicate the physical processes for fluid-structure interaction phenomena in bridge aerodynamics and aeroelasticity.}, subject = {Ingenieurwissenschaften}, language = {en} } @unpublished{KavrakovMorgenthal, author = {Kavrakov, Igor and Morgenthal, Guido}, title = {Aeroelastic analyses of bridges using a Pseudo-3D vortex method and velocity-based synthetic turbulence generation}, doi = {10.25643/bauhaus-universitaet.4086}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20200206-40864}, abstract = {The accurate representation of aerodynamic forces is essential for a safe, yet reasonable design of long-span bridges subjected to wind effects. In this paper, a novel extension of the Pseudo-three-dimensional Vortex Particle Method (Pseudo-3D VPM) is presented for Computational Fluid Dynamics (CFD) buffeting analysis of line-like structures. This extension entails an introduction of free-stream turbulent fluctuations, based on the velocity-based turbulence generation. The aerodynamic response of a long-span bridge is obtained by subjecting the 3D dynamic representation of the structure to correlated free-stream turbulence in two-dimensional (2D) fluid planes, which are positioned along the bridge deck. The span-wise correlation of the free-stream turbulence between the 2D fluid planes is established based on Taylor's hypothesis of frozen turbulence. Moreover, the application of the laminar Pseudo-3D VPM is extended to a multimode flutter analysis. Finally, the structural response from the Pseudo-3D flutter and buffeting analyses is verified with the response, computed using the semi-analytical linear unsteady model in the time-domain. Meaningful merits of the turbulent Pseudo-3D VPM with respect to the linear unsteady model are the consideration of the 2D aerodynamic nonlinearity, nonlinear fluid memory, vortex shedding and local non-stationary turbulence effects in the aerodynamic forces. The good agreement of the responses for the two models in the 3D analyses demonstrates the applicability of the Pseudo-3D VPM for aeroelastic analyses of line-like structures under turbulent and laminar free-stream conditions.}, subject = {Bridge}, language = {en} } @unpublished{MosaviTorabiHashemietal., author = {Mosavi, Amir and Torabi, Mehrnoosh and Hashemi, Sattar and Saybani, Mahmoud Reza and Shamshirband, Shahaboddin}, title = {A Hybrid Clustering and Classification Technique for Forecasting Short-Term Energy Consumption}, doi = {10.25643/bauhaus-universitaet.3755}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20180907-37550}, abstract = {Electrical energy distributor companies in Iran have to announce their energy demand at least three 3-day ahead of the market opening. Therefore, an accurate load estimation is highly crucial. This research invoked methodology based on CRISP data mining and used SVM, ANN, and CBA-ANN-SVM (a novel hybrid model of clustering with both widely used ANN and SVM) to predict short-term electrical energy demand of Bandarabbas. In previous studies, researchers introduced few effective parameters with no reasonable error about Bandarabbas power consumption. In this research we tried to recognize all efficient parameters and with the use of CBA-ANN-SVM model, the rate of error has been minimized. After consulting with experts in the field of power consumption and plotting daily power consumption for each week, this research showed that official holidays and weekends have impact on the power consumption. When the weather gets warmer, the consumption of electrical energy increases due to turning on electrical air conditioner. Also, con-sumption patterns in warm and cold months are different. Analyzing power consumption of the same month for different years had shown high similarity in power consumption patterns. Factors with high impact on power consumption were identified and statistical methods were utilized to prove their impacts. Using SVM, ANN and CBA-ANN-SVM, the model was built. Sine the proposed method (CBA-ANN-SVM) has low MAPE 5 1.474 (4 clusters) and MAPE 5 1.297 (3 clusters) in comparison with SVM (MAPE 5 2.015) and ANN (MAPE 5 1.790), this model was selected as the final model. The final model has the benefits from both models and the benefits of clustering. Clustering algorithm with discovering data structure, divides data into several clusters based on similarities and differences between them. Because data inside each cluster are more similar than entire data, modeling in each cluster will present better results. For future research, we suggest using fuzzy methods and genetic algorithm or a hybrid of both to forecast each cluster. It is also possible to use fuzzy methods or genetic algorithms or a hybrid of both without using clustering. It is issued that such models will produce better and more accurate results. This paper presents a hybrid approach to predict the electric energy usage of weather-sensitive loads. The presented methodutilizes the clustering paradigm along with ANN and SVMapproaches for accurate short-term prediction of electric energyusage, using weather data. Since the methodology beinginvoked in this research is based on CRISP data mining, datapreparation has received a gr eat deal of attention in thisresear ch. Once data pre-processing was done, the underlyingpattern of electric energy consumption was extracted by themeans of machine learning methods to precisely forecast short-term energy consumption. The proposed approach (CBA-ANN-SVM) was applied to real load data and resulting higher accu-racy comparing to the existing models. 2018 American Institute of Chemical Engineers Environ Prog, 2018 https://doi.org/10.1002/ep.12934}, subject = {Data Mining}, language = {en} } @unpublished{MosaviMoeiniAhmadpouretal., author = {Mosavi, Amir and Moeini, Iman and Ahmadpour, Mohammad and Alharbi, Naif and E. Gorji, Nima}, title = {Modeling the time-dependent characteristics of perovskite solar cells}, doi = {10.25643/bauhaus-universitaet.3757}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20180907-37573}, abstract = {We proposed two different time-dependent modeling approaches for variation of device characteristics of perovskite solar cells under stress conditions. The first approach follows Sah-Noyce-Shockley (SNS) model based on Shockley-Read-Hall recombination/generation across the depletion width of pn junction and the second approach is based on thermionic emission model for Schottky diodes. The connecting point of these approaches to time variation is the time-dependent defect generation in depletion width (W) of the junction. We have fitted the two models with experimental data reported in the literature to perovskite solar cell and found out that each model has a superior explanation for degradation of device metrics e.g. current density and efficiency by time under stress conditions. Nevertheless, the Sah-Noyce-Shockley model is more reliable than thermionic emission at least for solar cells.}, subject = {Solarzelle}, language = {en} } @unpublished{SimonRitzRudolf, author = {Simon-Ritz, Frank and Rudolf, Sylvelin}, title = {Ein Schaufenster f{\"u}r die Kunst}, volume = {69}, number = {Heft 6}, doi = {10.25643/bauhaus-universitaet.3230}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20170711-32307}, pages = {312 -- 317}, abstract = {Kunstausstellungen in Bibliotheken}, subject = {Ausstellung}, language = {de} } @unpublished{KoenigMueller2011, author = {K{\"o}nig, Reinhard and M{\"u}ller, Daniela}, title = {Cellular-Automata-Based Simulation of the Settlement Development in Vienna}, isbn = {978-953-307-230-2}, doi = {10.25643/bauhaus-universitaet.1450}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20110415-15449}, year = {2011}, abstract = {The motivation to deal with the topic simulation of the settlement development in a city in the past 120 years has been to acquire general methods for the analysis and simulation of settlement development processes on the one hand and to verify these methods on the example of the real development of the city of Vienna on the other hand. We follow the assumption that the underlying processes of the urban development can be reduced to various pronounced but always the same hidden driving forces. The objective is to validate the simulation model by the real settlement development and to provide a solid base for the simulation of possible development scenarios of the city of Vienna. The basis for the validation are digital cellular processed and statistical analysed data of the development of the technical infrastructure, the public transportation systems and the population density in Vienna between 1888 and 2001. The simulation method is based on the technique of Cellular Automata (CA) that permits the simulation of the interaction between a potential field and the development of individual areas. This modelling technique is well known as "reaction diffusion" or "dialectic breakdown". The CA serves as representation of the examined space and divides this space into individual cells. Each of these cells can save certain information (population density, infrastructure facility, development quality) and exchange them locally with the neighbouring cells. The used model parameters permit the simulation of different spread patterns und spread speeds of a settlement structure. From the results methodological, structural, spatial and temporal regularities of urban development processes are derived.}, subject = {Computersimulation}, language = {en} }