Fakultäten & Zentralinstitute

8494 Items

Recent Submissions
Discrete Yamabe problem for polyhedral surfaces

Kourimska, Hana ; Springborn, Boris (2019-09-13)

We introduce a new discretization of the Gaussian curvature on piecewise at surfaces. As the prime new feature the curvature is scaled by the factor 1/r2 upon scaling the metric globally with the factor r. We develop a variational principle to tackle the corresponding discrete uniformisation theorem – we show that each piecewise at surface is discrete conformally equivalent to one with constant...

Processing Effects on the Formability of Magnesium Alloy Sheets

Bohlen, Jan ; Cano, Guadalupe ; Drozdenko, Daria ; Dobron, Patrik ; Kainer, Karl ; Gall, Sven ; Müller, Sören ; Letzig, Dietmar (2018-02-23)

As a generalized semi-finished product, the use of magnesium sheets requires addressing two major aspects of their processing: their microstructure and texture control, which are both essential for the forming behavior of such sheets during their forming to parts. Further, the processing of such sheets is complex, and therefore expensive, and requires simplification. In this work, magnesium all...

A Way Out of the Bubble Trouble?—Upon Reconstructing the Origin of the Local Bubble and Loop I via Radioisotopic Signatures on Earth

Schulreich, Michael ; Breitschwerdt, Dieter ; Feige, Jenny ; Dettbarn, Christian (2018-02-25)

Deep-sea archives all over the world show an enhanced concentration of the radionuclide 60Fe, isolated in layers dating from about 2.2 Myr ago. Since this comparatively long-lived isotope is not naturally produced on Earth, such an enhancement can only be attributed to extraterrestrial sources, particularly one or several nearby supernovae in the recent past. It has been speculated that these s...

Structural Analysis of a Modern o/w-Emulsion Stabilized by a Polyglycerol Ester Emulsifier and Consistency Enhancers

Dahl, Verena ; Friedrich, Achim ; Meyer, Jürgen ; Venzmer, Joachim ; Belkoura, Lhoussaine ; Strey, Reinhard ; Mayer, Christian ; Michel, Raphael ; Gradzielski, Michael (2018-01-18)

The aim of our work was to study the structure of a typical modern cosmetic oil-in-water emulsion (o/w-emulsion), based on the emulsifier polyglyceryl-3 dicitrate/stearate and glycerylstearate/stearyl alcohol as consistency enhancer. We have used a systematic approach building up the cosmetic emulsion step by step, characterizing all systems by using Small Angle Neutron Scattering (SANS), Diffe...

Sea Ice Detection Based on Differential Delay-Doppler Maps from UK TechDemoSat-1

Zhu, Yongchao ; Yu, Kegen ; Zou, Jingui ; Wickert, Jens (2017-07-12)

Global Navigation Satellite System (GNSS) signals can be exploited to remotely sense atmosphere and land and ocean surface to retrieve a range of geophysical parameters. This paper proposes two new methods, termed as power-summation of differential Delay-Doppler Maps (PS-D) and pixel-number of differential Delay-Doppler Maps (PN-D), to distinguish between sea ice and sea water using differentia...

Imaging with Polarized Neutrons

Kardjilov, Nikolay ; Hilger, André ; Manke, Ingo ; Strobl, Markus ; Banhart, John (2018-01-16)

Owing to their zero charge, neutrons are able to pass through thick layers of matter (typically several centimeters) while being sensitive to magnetic fields due to their intrinsic magnetic moment. Therefore, in addition to the conventional attenuation contrast image, the magnetic field inside and around a sample can be visualized by detecting changes of polarization in a transmitted beam. The ...

The Natural Fungal Metabolite Beauvericin Exerts Anticancer Activity In Vivo: A Pre-Clinical Pilot Study

Heilos, Daniela ; Rodríguez-Carrasco, Yelko ; Englinger, Bernhard ; Timelthaler, Gerald ; Van Schoonhoven, Sushilla ; Sulyok, Michael ; Boecker, Simon ; Süßmuth, Roderich D. ; Heffeter, Petra ; Lemmens-Gruber, Rosa ; Dornetshuber-Fleiss, Rita ; Berger, Walter (2017-08-24)

Recently, in vitro anti-cancer properties of beauvericin, a fungal metabolite were shown in various cancer cell lines. In this study, we assessed the specificity of this effect by comparing beauvericin cytotoxicity in malignant versus non-malignant cells. Moreover, we tested in vivo anticancer effects of beauvericin by treating BALB/c and CB-17/SCID mice bearing murine CT-26 or human KB-3-1-gra...

Sustainability Assessment of Out-of-Home Meals: Potentials and Challenges of Applying the Indicator sets NAHGAST Meal-Basic and NAHGAST Meal-Pro

Engelmann, Tobias ; Speck, Melanie ; Rohn, Holger ; Bienge, Katrin ; Langen, Nina ; Howell, Eva ; Göbel, Christine ; Friedrich, Silke ; Teitscheid, Petra ; Bowry, Jaya ; Liedtke, Christa ; Monetti, Silvia (2018-02-23)

Nutrition is responsible for about 30% of global natural resource use. In order to limit the negative impact the nutritional sector has on the environment and on society, the consumption and processing of foodstuffs with assumed low negative impact is an important topic in the effort of sustainable development. In professional kitchens, clearly defined indicators assessing the impact of busines...

Wear Analysis of a Heterogeneous Annular Cylinder

Li, Qiang ; Forsbach, Fabian ; Schuster, Maximilian ; Pielsticker, Daniel ; Popov, Valentin L. (2018-03-18)

Wear of a cylindrical punch composed by two different materials alternatively distributed in annular forms is studied with the method of dimensionality reduction (MDR). The changes in surface topography and pressure distribution during the wear process is obtained and validated by the boundary element method (BEM). The pressure in each annular ring approaches a constant in a stationary state wh...

Numerical Assessment of Virtual Control Surfaces for Load Alleviation on Compressor Blades

Motta, Valentina ; Malzacher, Leonie ; Peitsch, Dieter (2018-01-17)

Virtual control surfaces for the optimization of steady and unsteady airloads on a compressor cascade are assessed numerically. The effects of mechanical surfaces are realized with plasma actuators, located both on the pressure and on the suction side of the blade trailing edge. Suction side plasma actuation is thought to reproduce the effects of mechanical wing spoilers, whereas pressure side ...

Robust motion generation for mobile manipulation — integrating control and planning under uncertainty

Sieverling, Arne (2019)

This thesis contributes to algorithmic approaches for the motion generation problem for mobile manipulators. This problem is unsolved in unstructured environments, where the robot does not have access to precise models but must infer the state of the world with its sensors. The challenges for motion generation in these problems arise from the uncertainty prevalent in real world sensors, the dif...

Room Acoustical Parameters as Predictors of Room Acoustical Impression: What Do We Know and What Would We Like to Know?

Weinzierl, Stefan ; Vorländer, Michael (2015-02-26)

Room acoustical parameters are audio features, usually extracted from monaural or binaural measurements of room acoustical environments, and used to predict different aspects of the ‘room acoustical impression’. The paper takes a closer look at the nature of this perceptional construct and at different approaches to develop a psychological measuring instrument for the multidimensional perceptio...

Scalable and efficient distributed self-healing with self-optimization features in fixed IP networks

Tcholtchev, Nikolay (2019)

The Internet is continuously gaining importance in our society. Indeed, the Internet is slowly turning into the backbone of the modern world, having impact on all possible aspects, such as politics, communication, intercultural exchange, and emergency services, to give some examples. As these aspects are developing, the technical infrastructure around the Internet’s core protocol - IP (Internet...

Generation and analysis of an acoustic radiation pattern database for forty-one musical instruments

Shabtai, Noam R. ; Behler, Gottfried ; Vorländer, Michael ; Weinzierl, Stefan (2017-02-28)

A database of acoustic radiation patterns was recorded, modeled, and analyzed for 41 modern or authentic orchestral musical instruments. The generation of this database included recordings of each instrument over the entire chromatic tone range in an anechoic chamber using a surrounding spherical microphone array. Acoustic source centering was applied in order to align the acoustic center of th...

Remote-Laser-Lichtquelle für ein hochaufgelöstes Scheinwerfersystem

Hansen, Julien (2019)

Der Bauraum im automobilen Scheinwerfer ist stark begrenzt. Daher wäre eine Entkopplung und Zentralisierung der Lichtquelleneinheit vorteilhaft. Ziel der vorliegenden Arbeit ist es, die Eigenschaften von Laserstrahlung zu nutzen, um eine effiziente Entkopplung der Lichtquelle vom hochaufgelösten Scheinwerfersystem mit Hilfe von Glasfasertechnologie zu realisieren. Für die Umsetzung dieser Remot...

Instruments for Spatial Sound Control in Real Time Music Performances. A Review

Pysiewicz, Andreas ; Weinzierl, Stefan (2016-12-10)

The systematic arrangement of sound in space is widely considered as one important compositional design category of Western art music and acoustic media art in the 20th century. A lot of attention has been paid to the artistic concepts of sound in space and its reproduction through loudspeaker systems. Much less attention has been attracted by live-interactive practices and tools for spatialisa...

Mixed Analytical-Numerical Filter Design for Optimized Electronic Control of Line Source Arrays

Straube, Florian ; Schultz, Frank ; Makarski, Michael ; Weinzierl, Stefan (2018-09-16)

Line source arrays (LSAs) are used for large-scale sound reinforcement that synthesizes homogeneous sound fields over the full audio bandwidth. The deployed loudspeaker cabinets are rigged with different tilt angles and are electronically controlled to provide the intended coverage of the audience zones and to avoid radiation toward the ceiling, reflective walls, or residential areas. In this a...

Prediction of speech intelligibility using pseudo-binaural room impulse responses

Kokabi, Omid ; Brinkmann, Fabian ; Weinzierl, Stefan (2019-04-29)

Head orientation (HO) affects better-ear-listening and spatial-release-from-masking, which are two key aspects in binaural speech intelligibility. To incorporate HO in speech intelligibility prediction, binaural room impulse responses (BRIRs) for every HO of interest could be used. Due to the limited spectral bandwidth of speech, however, approximate representations might be sufficient, which c...

Segmentation of binaural room impulse responses for speech intelligibility prediction

Kokabi, Omid ; Brinkmann, Fabian ; Weinzierl, Stefan (2018-11-16)

The two most important aspects in binaural speech perception—better-ear-listening and spatial-release-from-masking—can be predicted well with current binaural modeling frameworks operating on head-related impulse responses, i.e., anechoic binaural signals. To incorporate effects of reverberation, a model extension was proposed, splitting binaural room impulse responses into an early, useful, an...

Audibility and Interpolation of Head-Above-Torso Orientation in Binaural Technology

Brinkmann, Fabian ; Roden, Reinhild ; Lindau, Alexander ; Weinzierl, Stefan (2015-03-20)

Head-related transfer functions (HRTFs) incorporate fundamental cues required for human spatial hearing and are often applied to auralize results obtained from room acoustic simulations. HRTFs are typically available for various directions of sound incidence and a fixed head-above-torso orientation (HATO). If-in interactive auralizations-HRTFs are exchanged according to the head rotations of a ...