Technical University Muchen

Garching bei München, Germany

Technical University Muchen

Garching bei München, Germany
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Wang K.,Beihang University | Hu T.,China Aerospace Polytechnology Establishment | Hassabou A.H.,Technical University Muchen | Spinnler M.,Technical University Muchen | Polifke W.,Technical University Muchen
Continuum Mechanics and Thermodynamics | Year: 2013

Condensers serve as important components for humidification- dehumidification (HDH) desalination plants. Based on the interpenetration continua approach with volume averaging technique, a mathematical dynamic model for analyzing the heat and mass transfer within direct contact condensers with co-current or countercurrent flow arrangement was developed. It was validated against the experimental data from a small scale HDH desalination system. Comparisons including the productivities and the temperature profiles of gas, liquid, and solid phases show good agreement with the measurements. Phase change material (PCM) melting processes have little effect on water production rate for co-current flow arrangement, but the condenser packed with PCM capsules have higher water production rates than that packed with air capsules packed under given conditions. The relative humidity profile of the bulk gas shows contrary trend with the gas temperature profile. The direct contact condenser with countercurrent flow arrangement can provide much better heat and mass transfer between gas and water and produce about 16.3% more fresh water than the same condenser with co-current flow arrangement in 4 h under given conditions. © 2012 Springer-Verlag.

Pucillo F.,Polytechnic of Milan | Michailidou I.,Technical University Muchen | Cascini G.,Polytechnic of Milan | Lindemann U.,Polytechnic of Milan
Proceedings of NordDesign 2014 Conference, NordDesign 2014 | Year: 2014

Users' emotions are crucial for purchasing decisions. Designing products that evoke positive emotions requires knowledge about users and their psychological needs: the research on User Experience (UX) aims at creating such knowledge. Several UX researchers highlighted that positive emotions emerge in user/product interactions, when user's psychological motives and needs are met and her/his expectations fulfilled or exceeded. How can users' motives be acquired? User research in industrial practice usually contributes with insights about users in form personas, user feedback and interviews, but not explicitly with the motives to be addressed. This work aims at creating a systematic method for deriving and understanding users' motives through the analysis of stories, such as those in product reviews. The identified motives can serve as input for UX design. Thus, basing of existing techniques for the narrative analysis of stories, a method for extracting users' motives is proposed and an exemplary application shown.

Hu T.,Beihang University | Hu T.,Technical University Muchen | Hassabou A.H.,Technical University Muchen | Spinnler M.,Technical University Muchen | Polifke W.,Technical University Muchen
Desalination | Year: 2011

Aim of this work is to model, optimize and characterize the design of a direct contact condenser utilizing spherical phase change material (PCM) elements as a packing medium in a solar driven humidification-dehumidification (HDH) desalination plant. Assuming local thermal non-equilibrium and departing from the continuous solid phase model, a simplified one-dimensional heat and mass transfer model has been developed and solved using interpenetration continua approach with volume averaging technique. The model has been validated against experimental data and was then used for further parametric analysis. Comparison with measurements showed good agreement with less than 3% of the fresh water production rate. The thermal behavior of the new condenser equipment is discussed and analyzed. Fundamental variables and critical parameters affecting the system performance such as the effect of condenser geometrical aspect ratio, packing size, air to water mass flow rate ratio, PCM thermal properties, and the effect of different types of packing media were studied. A system parameters analysis and characteristic guidelines for the optimum parameters and operation conditions have been obtained and will be presented thoroughly. Comparative performance of the system is clearly documented using PCM and Non-PCM packing elements. © 2011 Elsevier B.V.

Kotzing T.,Friedrich - Schiller University of Jena | Palenta R.,Technical University Muchen
Theoretical Computer Science | Year: 2016

We investigate how different learning restrictions reduce learning power and how the different restrictions relate to one another. We give a complete map for nine different restrictions both for the cases of complete information learning and set-driven learning. This completes the picture for these well-studied delayable learning restrictions. A further insight is gained by different characterizations of conservative learning in terms of variants of cautious learning. Our analyses greatly benefit from general theorems we give, for example showing that learners which have to obey only delayable restrictions can always be assumed total. © 2016 Elsevier B.V.

Alpers A.,Technical University Muchen | Brieden A.,University der Bundeswehr Muchen | Gritzmann P.,Technical University Muchen | Lyckegaard A.,Xnovo Technology | Poulsen H.F.,Technical University of Denmark
Philosophical Magazine | Year: 2015

Characterizing the grain structure of polycrystalline material is an important task in material science. The present paper introduces the concept of generalized balanced power diagrams as a concise alternative to voxelated mappings. Here, each grain is represented by (measured approximations of) its centre of mass position, its volume and, if available, and by its second-order moments (in the non-equiaxed case). Such parameters may be obtained from 3D X-ray diffraction. As the exact global optimum of our model results from the solution of a suitable linear programme it can be computed quite efficiently. Based on verified real-world measurements, we show that from the few parameters per grain (3, respectively, 6 in 2D and 4, respectively, 10 in 3D) we obtain excellent representations of both equiaxed and non-equiaxed structures. Hence our approach seems to capture the physical principles governing the forming of such polycrystals in the underlying process quite well. © 2015 Taylor & Francis.

Sefidi K.,University of Tehran | Sefidi K.,University of Mohaghegh | Mohadjer M.R.M.,University of Tehran | Mosandl R.,Technical University Muchen | Copenheaver C.A.,Virginia Polytechnic Institute and State University
Natural Areas Journal | Year: 2013

As conservationists develop strategies for managing coarse woody debris in natural areas information on the volume and distribution of deadwood in relatively undisturbed forests provides a valuable baseline for management goals. Hyrcanian mixed hardwood forests, within middle elevations of the Alborz Mountains bordering the Caspian Sea in northern Iran, experience few human disturbances and provide an ideal study site to examine woody debris in a mature forest. This study had three object tives: (1) measure volume of coarse and fine woody debris in Hyrcanian mixed hardwood forests; (2) compare density of forms of coarse woody debris (stumps, logs, and snags); and (3) correlate volume of living trees with volume of coarse woody debris. To sample the density and volume of dead wood, 15 plots of 1 ha (coarse woody debris) and 15 plots of 4 m2 (fine woody debris) were established. Coarse woody debris had an average volume of 15 m3 ha-1 and fine woody debris had an average of 10 m3 ha-1. The most common form of coarse woody debris was logs (67%) and the most frequent species was Oriental beech (Fagus orientalis) (55%). The volume of Oriental beech coarse woody debris was no significantly correlated with the volume of living Oriental beech trees (P = 0.77); however, the volume of European hornbeam (Carpinus betulus) coarse woody debris was significantly correlated to the volume of living European hornbeam (P = 0.01). The volume of coarse woody debris found in this study was considerably lower than has been measured in other Oriental beech forests and this may be a long-tern effect of historical grazing practices at this site, which emphasizes the importance of gathering a full historical context for a forest before it is used as a baseline for conservation management.

Birle E.,Technical University Muchen | Boso M.,Technical University Muchen | Heyer D.,Technical University Muchen
Unsaturated Soils - Proceedings of the 5th International Conference on Unsaturated Soils | Year: 2011

The paper presents experimental results of the flow of water in an embankment built of clay with organic content. The organic soil used for the field test contains geogenetically elevated concentrations of arsenic. As it is planned to use it for noise and view protection embankments, the leachate to be expected at the bottom of the embankments is of great interest. For the measurement of the water balance of the test embankment, extensive measuring systems are installed. With these the flow of water in the dry and wet compacted organic clay can be investigated. Based on the measurements, the water flow in the compacted organic clay is analyzed with respect to the compaction water content. © 2011 Taylor & Francis Group, London.

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