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An Optimised Surface Structure for Passive, Unidirectional Fluid Transport Bioinspired by True Bugs

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Journal of Bionic Engineering 2021年第2期18卷 375-386页

作者： Sebastian Lifka Florian Hischen johannes Heitz Werner Baumgartner Institute of Biomedical Mechatronics Johannes Kepler University LinzAltenberger Straße 694040 LinzAustria Institute of Applied Physics Johannes Kepler University LinzAltenberger Straße 694040 LinzAustria

Some true bug species use droplet-shaped,open-capillary structures for passive,unidirectional fluid transport on their body surface in order to spread a defensive fluid to protect themselves against *** this paper we investigated if the shape of the structures found on bugs(bug-structure)could be optimised with regard to better performance in unidirectional fluid ***,to use this kind of surface structure in technical applications where fluid surface interaction occurs,it is necessary to adapt the structure geometry to the contact angle between fluid and *** on the principal of operation of the droplet-shaped structures,we optimised the structure shape for better performance in targeted fluid flow and increase in flexibility in design of the structure *** adapt the structure geometry and the structure spacing to the contact angle,we implemented an equilibrium simulation of the,the structure surrounding,*** order to verify the functionality of the optimised structure,we designed and manufactured a *** testing this prototype with pure water used as fluid,the functionality of the optimised structure and the simulation could be *** kind of structure may be used on technical surfaces where targeted fluid transport is needed,*** of condensate in order to prevent the surface from mold growth,microfluidics,lab-on-a-chip applications and on microneedles for efficient drug/vaccine coating.

关键词： biomimetics true bugs liquid-surface interaction passive unidirectional fluid transport microfluidics lab-on-a-chip

Battery package design optimization for small electric aircraft

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Chinese Journal of Aeronautics 2020年第11期33卷 2864-2876页

作者： Mingkai WANG Shuguang ZHANG johannes DIEPOLDER Florian HOLZAPFEL Institute of Aircraft Airworthiness Engineering School of Transportation Science and EngineeringBeihang UniversityBeijing 100083China Institute of Flight System Dynamics Department of Mechanical EngineeringTechnical University of MunichGarching D-85748Germany

The increasing gross weight of electric Unmanned Aerial Vehicle(UAV) poses a challenge in practical applications. The range and endurance of the electric UAV are limited by the fixed mass of the battery package. In this work, a design optimization method for the battery package topology of small electric UAV is proposed to enhance the performance. To improve the accuracy of the method, the dynamic battery model and simplified electric component models are *** models are utilized by the trajectory optimization method, which takes the dynamic characteristic into consideration to calculate the aircraft performance. The direct optimal control method is used for solving the trajectory optimization problem, and this method is tested on a small blended-wing-body electric aircraft. The test result shows that the range and energy-consumption are mainly influenced by the parallel topology of the battery package, while the flight time in climb phase is more sensitive to the series topology. It is deduced that the range-and energy-optimal design points can be considered concurrently in design optimization. The work proves the feasibility of integrating the trajectory optimization and battery package design.

关键词： Battery pack Design optimization Electric power system Trajectory optimization Unmanned Aerial Vehicle(UAV)

Real-time raster projection for web maps

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International Journal of Digital Earth 2016年第3期9卷 215-229页

作者： Bernhard Jenny Bojan Šavrič johannes Liem College of Earth Oceanand Atmospheric SciencesOregon State UniversityCorvallisORUSA

The virtual globe is the default visualization for Digital Earth applications,but it can only show one half of the *** article introduces user-adjustable,on-the-fly projection of georeferenced raster images for web mapping and web GIS *** technique allows users to center a map on arbitrary locations,while still seeing the entire Earth *** web mapping libraries can apply map projection transformations to vector data in the browser,but they do not currently support the projection of raster images at interactive frame *** use the cross-platform WebGL(Web Graphics Library)graphics pipeline for hardware-accelerated projection of raster data in web *** algorithmic techniques–inverse per-fragment projection,and combined forward per-triangle and inverse per-fragment projection–for georeferenced raster imagery are *** resulting raster maps combine the ease of use and flexibility of interactive virtual globes with the ability to show the entire *** adjustable projection of raster imagery allows users to observe global phenomena that are difficult to visualize on virtual globes or traditional maps with static projections.

关键词： map projection raster projection WebGL

Surface tracking assessment and interaction in texture space

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Computational Visual Media 2018年第1期4卷 3-15页

作者： johannes Furch Anna Hilsmann Peter Eisert Fraunhofer HHI Berlin10587Germany Humboldt University Berlin10099Germany

In this paper, we present a novel approach for assessing and interacting with surface tracking algorithms targeting video manipulation in postproduction. As tracking inaccuracies are unavoidable,we enable the user to provide small hints to the algorithms instead of correcting erroneous results afterwards. Based on 2D mesh warp-based optical flow estimation, we visualize results and provide tools for user feedback in a consistent reference system, texture space. In this space, accurate tracking results are reflected by static appearance, and errors can easily be spotted as apparent change. A variety of established tools can be utilized to visualize and assess the change between frames. User interaction to improve tracking results becomes more intuitive in texture space, as it can focus on a small region rather than a moving *** show how established tools can be implemented for interaction in texture space to provide a more intuitive interface allowing more effective and accurate user feedback.

关键词： surface tracking assessment interaction mesh warp optical flow

Studies of fiber-matrix debonding

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Frontiers of Structural and Civil Engineering 2015年第4期9卷 448-456页

作者： Navneet DRONAMRAJU johannes SOLASS Jorg HILDEBRAND Simulation und Experiment Bauhaus-Universitdt Weimar Weimar 99423 Germany

In this paper, the debonding of a single fiber-matrix system of carbon fiber reinforced composite (CFRP) AS4/Epson 828 material is studied using Cohesive Zone Model (CZM). The effect of parameters namely, maximum tangential contact stress, tangential slip distance and artificial damping coefficient on the debonding length at the interface of the fiber-matrix is analyzed. Contact elements used in the CZM are coupled based on a bilinear stress-strain curve. Load is applied on the matrix, tangential to the interface. Hence, debonding is observed primarily in Mode II. Wide range of values are considered to study the inter-dependency of the parameters and its effect on debonding length. Out of the three parameters mentioned, artificial damping coefficient and tangential slip distance significantly affect debonding length. A thorough investigation is recommended for case wise interface debonding analysis, to estimate the optimal parametric values while using CZM.

关键词： single fibre cohesive zone model interface debonding carbon fiber reinforced composite (CFRP)

Longitudinal height-diameter curves for Norway spruce, Scots pine and silver birch in Norway based on shape constraint additive regression models

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Forest Ecosystems 2018年第2期5卷 109-125页

作者： Matthias Schmidt johannes Breidenbach Rasmus Astrup Northwest German Forest Research Institute Forest Growth Gratzelstr 2 37079 Gottingen Germany Norwegian Institute for Bioeconomy Research National Forest Inventory Postboks 115 1431 As Norway

Background： Generalized height-diameter curves based on a re-parameterized version of the Korf function for Norway spruce （Piceo abies （L.） Karst.）, Scots pine （Pinus sylvestris L.） and silver birch （Betula pendula Roth） in Norwa are presented. The Norwegian National Forest Inventory （NFI） is used as data base for estimating the model parameters. The derived models are developed to enable spatially explicit and site sensitive tree height imputatio in forest inventories as well as future tree height predictions in growth and yield scenario simulations. Methods： Generalized additive mixed models （gamm） are employed to detect and quantify potentially non-linear effects of predictor variables. In doing so the quadratic mean diameter serves as longitudinal covariate since stand ag as measured in the NFI, shows only a weak correlation with a stands developmental status in Norwegian forests. Additionally the models can be locally calibrated by predicting random effects if measured height-diameter pairs are available. Based on the model selection of non-constraint models, shape constraint additive models （scare） were fit tc incorporate expert knowledge and intrinsic relationships by enforcing certain effect patterns like monotonicity. Results： Model comparisons demonstrate that the shape constraints lead to only marginal differences in statistical characteristics but ensure reasonable model predictions. Under constant constraints the developed models predict increasing tree heights with decreasing altitude, increasing soil depth and increasing competition pressure of a tree. / two-dimensional spatially structured effect of UTM-coordinates accounts for the potential effects of large scale spatial correlated covariates, which were not at our disposal. The main result of modelling the spatially structured effect is lower tree height prediction for coastal sites and with increasing latitude. The quadratic mean diameter affects both the level and the slope of the height-diameter

关键词： Height-diameter curve Norway spruce Scots pine Silver birch Norwegian national forest inventory Shape constrained additive models

Why did life develop on the surface of the Earth in the Cambrian？

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Geoscience Frontiers 2016年第6期7卷 865-873页

作者： Carlo Doglioni johannes Pignatti Max Coleman Department of Earth Sciences Sapienza University 00185 Rome Italy NASA Jet Propulsion Laboratory California Institute of Technology Pasadena CA 91109 USA NASA Astrobiology Institute USA

Life was limited for most of Earth＇s history, remaining at a primitive stage and mostly marine until about 0.55 Ga. In the Paleozoic, life eventually exploded and colonized the continental realm. Why had there been such a long period of delayed evolution of life？ Early life was dominated by Archaea and Bacteria, which can survive ionizing radiation better than other organisms. The magnetic field preserves the atmosphere, which is the main shield of UV radiation. We explore the hypothesis that the Cambrian explosion of life could have been enabled by the increase of the magnetic field dipole intensity due to the solidification of the inner core, caused by the cooling of the Earth, and the concomitant decrease with time of the high-energy solar flux since the birth of the solar system. Therefore, the two phenomena could be responsible for the growth and thickening of the atmosphere and the development of land surface life.

关键词： Origin of lifeInner core solidificationSolar ionizing radiations

Hydrological modelling in the anthroposphere: predicting local runoff in a heavily modified high-alpine catchment

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Journal of Mountain Science 2018年第5期15卷 921-938页

作者： johannes WESEMANN Mathew HERRNEGGER Karsten SCHULZ Institute of Water Management Hydrology and Hydraulic Engineering (IWHW) University of Natural Resources and Life Sciences Vienna (BOKU)

Hydrological models within inflow forecasting systems for high-alpine hydropower reservoirs can provide valuable information as part of a decision support system for the improvement of hydropower production or flood retention. The information, especially concerning runoff, is however rarely available for the calibration of the hydrological models used. Therefore, a method is presented to derive local runoff from secondary information for the calibration of the model parameters of the rainfallrunoff model COSERO. Changes in water levels in reservoirs, reservoir outflows, discharge measurements at water intakes and in transport lines are thereby used to derive the local, "natural" flow for a given sub-catchment. The proposed method is applied within a research study for the ?BB Infrastructure Railsystem division in the Stubache catchment in the central Austrian Alps. Here, the ?BB operates the hydropower scheme "Kraftwerksgruppe Stubachtal", which consists of 7 reservoirs and 4 hydropower stations. The hydrological model has been set up considering this human influences and the high natural heterogeneity in topography and land cover, including glaciers. Overall, the hydrological model performs mostly well for the catchment with highest NSE values of 0.78 for the calibration and0.79 for the validation period, also considering the use of homogeneous parameter fields and the uncertainty of the derived local discharge values. The derived runoff data proved to be useful information for the model calibration. Further analysis, examining the water balance and its components as well as snow cover, showed satisfactory simulation results. In conclusion, a unique runoff dataset for a small scale high-alpine catchment has been created to establish a hydrological flow prediction model which in a further step can be used for improved and sustainable hydropower management.

关键词： High alpine catchments Rainfall-runoff modelling Hydropower Ungauged basins

Using LIDAR and ground truth for landslide recognition and characterization of geotechnical and morphological parameters in sedimentary rocks,a case study in Northern Bavaria (Germany)

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Journal of Mountain Science 2017年第8期14卷 1513-1525页

作者： WIEDENMANN johannes ROHN Joachim MOSER Michael GeoZentrum Nordbayern Department of Applied GeologyUniversity of Erlangen-Nürnberg

The use of LIDAR-derived shaded relief maps led to the identification of all potential landslide areas in a hilly region in Northern Bavaria(1590 km^2), Germany. Every possible structure was investigated by field investigation which resulted in a detailed database of 1002 landslides within the study area. The analysis of geological, lithological, topographical and morphological properties(spatial ratio, lithological and geological setting, length/width distribution, material properties and slope angle) revealed characteristic appearances of the landslides and possible relationships between different aspects. Strong relations between the lithological setting, spatial ratio of the mapped landslides and distribution of slope angle could be observed. This study shows the value of high-resolution shaded relief maps for detecting and mapping landslides in a large area with comparatively little work and time in comparison to the traditional approach to mapping. It reveals that many landslides were not known before. Landslides are much more common in Northern Bavaria and have a higher influence on the denudation rate of the Franconian Alb than expected before.

关键词： Landslides LIDAR Appearance Spatialratio Material properties Bavaria