@article{NeuJanserKhatibietal.2016, author = {Neu, Eugen and Janser, Frank and Khatibi, Akbar A. and Orifici, Adrian C.}, title = {Automated modal parameter-based anomaly detection under varying wind excitation}, series = {Structural Health Monitoring}, volume = {15}, journal = {Structural Health Monitoring}, number = {6}, publisher = {Sage}, address = {London}, issn = {1475-9217}, doi = {10.1177/1475921716665803}, pages = {1 -- 20}, year = {2016}, abstract = {Wind-induced operational variability is one of the major challenges for structural health monitoring of slender engineering structures like aircraft wings or wind turbine blades. Damage sensitive features often show an even bigger sensitivity to operational variability. In this study a composite cantilever was subjected to multiple mass configurations, velocities and angles of attack in a controlled wind tunnel environment. A small-scale impact damage was introduced to the specimen and the structural response measurements were repeated. The proposed damage detection methodology is based on automated operational modal analysis. A novel baseline preparation procedure is described that reduces the amount of user interaction to the provision of a single consistency threshold. The procedure starts with an indeterminate number of operational modal analysis identifications from a large number of datasets and returns a complete baseline matrix of natural frequencies and damping ratios that is suitable for subsequent anomaly detection. Mahalanobis distance-based anomaly detection is then applied to successfully detect the damage under varying severities of operational variability and with various degrees of knowledge about the present operational conditions. The damage detection capabilities of the proposed methodology were found to be excellent under varying velocities and angles of attack. Damage detection was less successful under joint mass and wind variability but could be significantly improved through the provision of the currently encountered operational conditions.}, language = {en} } @article{BialonskiCaronSchloenetal.2016, author = {Bialonski, Stephan and Caron, David A. and Schloen, Julia and Feudel, Ulrike and Kantz, Holger and Moorthi, Stefanie D.}, title = {Phytoplankton dynamics in the Southern California Bight indicate a complex mixture of transport and biology}, series = {Journal of Plankton Research}, volume = {38}, journal = {Journal of Plankton Research}, number = {4}, publisher = {Oxford University Press}, address = {Oxford}, issn = {1464-3774}, doi = {10.1093/plankt/fbv122}, pages = {1077 -- 1091}, year = {2016}, abstract = {The stimulation and dominance of potentially harmful phytoplankton taxa at a given locale and time are determined by local environmental conditions as well as by transport to or from neighboring regions. The present study investigated the occurrence of common harmful algal bloom (HAB) taxa within the Southern California Bight, using cross-correlation functions to determine potential dependencies between HAB taxa and environmental factors, and potential links to algal transport via local hydrography and currents. A simulation study, in which Lagrangian particles were released, was used to assess travel times due to advection by prevailing ocean currents in the bight. Our results indicate that transport of some taxa may be an important mechanism for the expansion of their distributions into other regions, which was supported by mean travel times derived from our simulation study and other literature on ocean currents in the Southern California Bight. In other cases, however, phytoplankton dynamics were rather linked to local environmental conditions, including coastal upwelling events. Overall, our study shows that complex current patterns in the Southern California Bight may contribute significantly to the formation and expansion of HABs in addition to local environmental factors determining the spatiotemporal dynamics of phytoplankton blooms.}, language = {en} } @article{MykoniouButenwegHoltschoppenetal.2016, author = {Mykoniou, Konstantin and Butenweg, Christoph and Holtschoppen, Britta and Klinkel, Sven}, title = {Seismic response analysis of adjacent liquid-storage tanks}, series = {Earthquake engineering and structural dynamics}, volume = {45}, journal = {Earthquake engineering and structural dynamics}, number = {11}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {1096-9845 (E-Journal); 0098-8847 (Print)}, doi = {10.1002/eqe.2726}, pages = {1779 -- 1796}, year = {2016}, abstract = {A refined substructure technique in the frequency domain is developed, which permits consideration of the interaction effects among adjacent containers through the supporting deformable soil medium. The tank-liquid systems are represented by means of mechanical models, whereas discrete springs and dashpots stand for the soil beneath the foundations. The proposed model is employed to assess the responses of adjacent circular, cylindrical tanks for harmonic and seismic excitations over wide range of tank proportions and soil conditions. The influence of the number, spatial arrangement of the containers and their distance on the overall system's behavior is addressed. The results indicate that the cross-interaction effects can substantially alter the impulsive components of response of each individual element in a tank farm. The degree of this impact is primarily controlled by the tank proportions and the proximity of the predominant natural frequencies of the shell-liquid-soil systems and the input seismic motion. The group effects should be not a priori disregarded, unless the tanks are founded on shallow soil deposit overlying very stiff material or bedrock.}, language = {en} } @article{PeloniCeriottiDachwald2016, author = {Peloni, Alessandro and Ceriotti, Matteo and Dachwald, Bernd}, title = {Solar-sail trajectory design for a multiple near-earth-asteroid rendezvous mission}, series = {Journal of Guidance, Control, and Dynamics}, volume = {39}, journal = {Journal of Guidance, Control, and Dynamics}, number = {12}, publisher = {AIAA}, address = {Reston, Va.}, issn = {0731-5090}, doi = {10.2514/1.G000470}, pages = {2712 -- 2724}, year = {2016}, abstract = {The scientific interest for near-Earth asteroids as well as the interest in potentially hazardous asteroids from the perspective of planetary defense led the space community to focus on near-Earth asteroid mission studies. A multiple near-Earth asteroid rendezvous mission with close-up observations of several objects can help to improve the characterization of these asteroids. This work explores the design of a solar-sail spacecraft for such a mission, focusing on the search of possible sequences of encounters and the trajectory optimization. This is done in two sequential steps: a sequence search by means of a simplified trajectory model and a set of heuristic rules based on astrodynamics, and a subsequent optimization phase. A shape-based approach for solar sailing has been developed and is used for the first phase. The effectiveness of the proposed approach is demonstrated through a fully optimized multiple near-Earth asteroid rendezvous mission. The results show that it is possible to visit five near-Earth asteroids within 10 years with near-term solar-sail technology.}, language = {en} } @article{BungValero2016, author = {Bung, Daniel Bernhard and Valero, Daniel}, title = {Optical flow estimation in aerated flows}, series = {Journal of Hydraulic Research}, volume = {54}, journal = {Journal of Hydraulic Research}, number = {5}, publisher = {Taylor \& Francis}, address = {London}, doi = {10.1080/00221686.2016.1173600}, pages = {575 -- 580}, year = {2016}, abstract = {Optical flow estimation is known from Computer Vision where it is used to determine obstacle movements through a sequence of images following an assumption of brightness conservation. This paper presents the first study on application of the optical flow method to aerated stepped spillway flows. For this purpose, the flow is captured with a high-speed camera and illuminated with a synchronized LED light source. The flow velocities, obtained using a basic Horn-Schunck method for estimation of the optical flow coupled with an image pyramid multi-resolution approach for image filtering, compare well with data from intrusive conductivity probe measurements. Application of the Horn-Schunck method yields densely populated flow field data sets with velocity information for every pixel. It is found that the image pyramid approach has the most significant effect on the accuracy compared to other image processing techniques. However, the final results show some dependency on the pixel intensity distribution, with better accuracy found for grey values between 100 and 150.}, language = {en} } @article{ButenwegMarinkovicKubalskietal.2016, author = {Butenweg, Christoph and Marinkovic, Marko and Kubalski, Thomas and Klinkel, Sven}, title = {Masonry infilled reinforced concrete frames under horizontal loading}, series = {Mauerwerk}, volume = {20}, journal = {Mauerwerk}, number = {4}, publisher = {Ernst \& Sohn}, address = {Berlin}, issn = {1437-1022}, doi = {10.1002/dama.201600703}, pages = {305 -- 312}, year = {2016}, abstract = {The behaviour of infilled reinforced concrete frames under horizontal load has been widely investigated, both experimentally and numerically. Since experimental tests represent large investments, numerical simulations offer an efficient approach for a more comprehensive analysis. When RC frames with masonry infill walls are subjected to horizontal loading, their behaviour is highly non-linear after a certain limit, which makes their analysis quite difficult. The non-linear behaviour results from the complex inelastic material properties of the concrete, infill wall and conditions at the wall-frame interface. In order to investigate this non-linear behaviour in detail, a finite element model using a micro modelling approach is developed, which is able to predict the complex non-linear behaviour resulting from the different materials and their interaction. Concrete and bricks are represented by a non-linear material model, while each reinforcement bar is represented as an individual part installed in the concrete part and behaving elasto-plastically. Each brick is modelled individually and connected taking into account the non-linearity of a brick mortar interface. The same approach is followed using two finite element software packages and the results are compared with the experimental results. The numerical models show a good agreement with the experiments in predicting the overall behaviour, but also very good matching for strength capacity and drift. The results emphasize the quality and the valuable contribution of the numerical models for use in parametric studies, which are needed for the derivation of design recommendations for infilled frame structures.}, language = {en} } @article{TuraliyevaYeshibaevSaparbekovaetal.2016, author = {Turaliyeva, M. and Yeshibaev, A. and Saparbekova, A. and Akynova, L. and Abildayeva, R. and Sadenova, M. and Sartayeva, K. and Schieffer, Andre and Digel, Ilya}, title = {Species composition and injuriousness of stranger xylophilous fauna affecting indigenous urban dendroflora of Central Asia}, series = {Asian journal of microbiology, biotechnology \& environmental sciences : AJMBES}, volume = {18}, journal = {Asian journal of microbiology, biotechnology \& environmental sciences : AJMBES}, number = {2}, publisher = {EM International}, issn = {0972-3005}, pages = {359 -- 366}, year = {2016}, abstract = {At the present time, one of the most serious environmental problems of Central Asia and South Kazakhstan is the ongoing large-scale deterioration of principal urban tree populations. Several major centers of massive spread of invasive plant pests have been found in urban dendroflora of this region. The degree of damage of seven most wide-spread aboriginal tree species was found to range from 21.4±1.1 to 85.4±1.8\%. In particular, the integrity of the native communities of sycamore (Platanus spp.), willow (Salix spp.), poplar (Populus spp.) and elm (Ulmus spp.) is highly endangered. Our taxonomic analysis of the most dangerous tree pests of the region has revealed them as neobiontic xylophilous insects such as Cossus cossus L. (Order: Lepidoptera L.) Monochamus urussovi Fisch., Monochamus sutor L., Acanthocinus aedelis L. and {\~N}etonia aureate L. (Order: Coleoptera L.). We relate the origin of this threatening trend with the import of industrial wood in the mid 90’s of the last century that was associated with high degree of the constructional work in the region. Because of the absence of efficient natural predators of the pest species, the application of microbiological methods of the pest control and limitation is suggested.}, language = {en} } @article{SchifferFerrein2016, author = {Schiffer, Stefan and Ferrein, Alexander}, title = {Decision-Theoretic Planning with Fuzzy Notions in GOLOG}, series = {International Journal of Uncertainty, Fuzziness and Knowledge-Based Systems}, volume = {24}, journal = {International Journal of Uncertainty, Fuzziness and Knowledge-Based Systems}, number = {Issue Suppl. 2}, publisher = {World Scientific}, address = {Singapur}, issn = {1793-6411}, doi = {10.1142/S0218488516400134}, pages = {123 -- 143}, year = {2016}, abstract = {In this paper we present an extension of the action language Golog that allows for using fuzzy notions in non-deterministic argument choices and the reward function in decision-theoretic planning. Often, in decision-theoretic planning, it is cumbersome to specify the set of values to pick from in the non-deterministic-choice-of-argument statement. Also, even for domain experts, it is not always easy to specify a reward function. Instead of providing a finite domain for values in the non-deterministic-choice-of-argument statement in Golog, we now allow for stating the argument domain by simply providing a formula over linguistic terms and fuzzy uents. In Golog's forward-search DT planning algorithm, these formulas are evaluated in order to find the agent's optimal policy. We illustrate this in the Diner Domain where the agent needs to calculate the optimal serving order.}, language = {en} } @article{FerreinSteinbauer2016, author = {Ferrein, Alexander and Steinbauer, Gerald}, title = {The Interplay of Aldebaran and RoboCup}, series = {KI - K{\"u}nstliche Intelligenz}, volume = {30}, journal = {KI - K{\"u}nstliche Intelligenz}, number = {3-4}, publisher = {Springer}, address = {Berlin}, issn = {1610-1987}, doi = {10.1007/s13218-016-0440-1}, pages = {325 -- 326}, year = {2016}, language = {en} } @article{HacklLeschingerStaatetal.2016, author = {Hackl, Michael and Leschinger, T. and Staat, Manfred and M{\"u}ller, Lars-Peter and Wegmann, Kilian}, title = {Reconstruction of the interosseous membrane in the Essex Lopresti lesion — a biomechanical evaluation}, series = {Knee surgery, sports traumatology, arthroscopy}, volume = {Volume 24}, journal = {Knee surgery, sports traumatology, arthroscopy}, number = {Supplement 1}, publisher = {Springer}, address = {Berlin}, issn = {0942-2056}, doi = {10.1007/s00167-016-4080-7}, pages = {130 -- 131}, year = {2016}, abstract = {Surgical reconstruction of the interosseous membrane (IOM) could restore longitudinal forearm stability to avoid persisting disability due to capituloradial and ulnocarpal impingement in Essex Lopresti lesions. This biomechanical study aimed to assess longitudinal forearm stability of intact specimens, after sectioning of the IOM and after reconstruction with a TightRope construct using either a single or double bundle technique.}, language = {en} }