Fak. 5 Verkehrs- und Maschinensysteme

821 Items

Recent Submissions
Benchmarking minimum passenger waiting time in online taxi dispatching with exact offline optimization methods

Maciejewski, Michał (2014)

This paper analyses the use of exact offline optimization methods for benchmarking online taxi dispatching strategies where the objective is to minimize the total passenger waiting time. First, a general framework for simulating dynamic transport services in MATSim (Multi-Agent Transport Simulation) is described. Next, the model of online taxi dispatching is defined, followed by a formulation o...

Multi-agent transport simulations and economic evaluation

Nagel, Kai ; Grether, Dominik ; Beuck, Ulrike ; Chen, Yu ; Rieser, Marcel ; Axhausen, Kay W. (2008)

Tolls are frequently discussed policies to reduce traffic in cities. However, road pricing measures are seldom implemented due to high investments and unpopularity. Transportation planning tools can support planning authorities by solving those problems if they take into account the following aspects: – Demographic attributes like income and time constraints – Time reactions to the policy – ...

FEM-gestützte Analyse der linear-elastischen und hyperelastischen eigengravitierenden Erde unter dem Aspekt geometrischer und physikalischer Nichtlinearitäten

Lofink, Paul (2018)

Die vorliegende Arbeit befasst sich mit der Deformation der Erde aufgrund der Eigengravitation. Es werden zunächst kontinuumstheoretische Grundlagen vorgestellt. Dabei werden mechanische und thermodynamische Gesetze erläutert. Um das System aus Feldgleichungen zu schließen, werden nach der Methode von Coleman-Noll thermodynamisch-konsistente Materialgesetze hergeleitet. Das Eigengravitationsp...

Reduction in the run-up distance for the deflagration-to-detonation transition and applications to pulse detonation combustion

Gray, Joshua Allen Terry (2018)

Pressure-gain combustion has been a topic of research interest for severald ecades. Due to the potential of pressure-gain thermodynamic cycles of increasing gas turbine effciency by more than 10%, they offer a strategy to combat the growing problem of continually scarcer resources by simultaneous enforcement of ever stricter emissions controls. Furthermore, when hydrogen is used as a fuel, emis...

Experimental investigations of mixing characteristics in model rotating detonation engine geometries

Blümner, Richard ; Bohon, Myles D. ; Gutmark, Ephraim J. ; Paschereit, Christian Oliver (2017)

This work examines the mechanisms of reactant mixing in a model Rotating Detonation Engine (RDE) geometry. RDEs are emerging as one of the highest potential applications for achieving Pressure Gain Combustion (PGC). Reactant mixing has been identified as a crucial component of efficient RDE operation. Therefore, a scaled model of a typical RDE engine geometry was examined in a water tunnel usin...

Modern methods for investigating the stability of a pitching floating platform wind turbine

Lennie, Matthew ; Marten, David ; Pechlivanoglou, George ; Nayeri, Christian Navid ; Paschereit, Christian Oliver (2017)

The QBlade implementation of the lifting-line free vortex wake (LLFVW) method was tested in conditions analogous to floating platform motion. Comparisons against two independent test cases using a variety of simulation methods show good agreement in thrust forces, rotor power, blade forces and rotor plane induction. Along with the many verifications already undertaken in the literature, it seem...

Theoretical and experimental investigations of creep groan in automotive disk brakes

Xingwei, Zhao (2018)

Due to the increasing comfort claims of customers, the study on low frequency creep groan has been receiving increasing attention currently. This thesis forces on the study of the fundamental mechanism of creep groan theoretically and experimentally. In order to understand creep groan step by step, the design of test rigs concentrating on creep groan are presented. A test rig with an idealized...

Design parameters of vortex pumps

Gerlach, Angela ; Thamsen, Paul Uwe ; Wulff, Sebastian ; Brix Jacobsen, Christian (2017)

Vortex pumps can impel solid-containing fluids and are therefore widely applied, from wastewater transport to the food industry. Despite constant efforts to improve vortex pumps, however, they have remained relatively inefficient compared to conventional centrifugal pumps. To find an optimized design of vortex pumps, this paper provides a systematic analysis on experimental studies that investi...

Physics of prestall propagating disturbances in axial compressors and their potential as a stall warning indicator

Eck, Mario ; Geist, Silvio ; Peitsch, Dieter (2017)

Axial compressors in aero engines are prone to suffering a breakdown of orderly flow when operating at the peak of the pressure rise characteristic. The damaging potential of separated flows is why a safe distance has to be left between every possible operating point and an operating point at which stall occurs. During earlier investigations of stall inception mechanisms, a new type of prestall...

Model reduction of components and assemblies made of composite materials as part of complex technical systems to simulate the overall dynamic behaviour

Peredo Fuentes, Humberto (2017)

The composite components and model order reduction (MOR) methods are widely used to improve the weight/strength ratio and the computational time respectively in different areas of the industry. The objective of this research is to evaluate the dynamic behaviour applying a MOR method in a composite component assembly. A new mixed numerical-experimental technique (MNET) is developed to obtain acc...

Neue MKS-FEM-Methode zur direkten Integration geometrischer und/oder materieller Nichtlinearitäten in die Simulation deformierbarer Mehrkörpersysteme

Nguyen, Viet Anh (2017)

Die vorliegende Arbeit präsentiert neue Möglichkeiten zur effizienten Behandlung geometrisch- und/oder physikalisch-nichtlinearer Probleme in der Dynamik deformierbarer Mehrkörpersystemen (MKS). Dabei werden beliebig große Starrkörperrotationen und nichtlineares Materialverhalten der Komponenten direkt in das Bewegungsgleichungssystem des Mehrkörpersystems einbezogen. Keine Co-Simulations- oder...

An analytical framework for the structural stability analysis of damageable structures and its application to delaminated composites

Köllner, Anton (2017)

In the current work, a novel analytical framework is developed which extends the general elastic stability theory to certain non-conservative deformation processes for which an extended total potential energy can be derived. The extended total potential energy constitutes the governing functional for the non-conservative deformation processes. The mechanical systems considered are described by ...

What is the “Source” of Open Source Hardware?

Bonvoisin, Jérémy ; Mies, Robert ; Boujut, Jean-François ; Stark, Rainer (2017)

What “open source” means once applied to tangible products has been so far mostly addressed through the light of licensing. While this approach is suitable for software, it appears to be over-simplistic for complex hardware products. Whether such a product can be labelled as open source is not only a question of licence but a question of documentation, i.e. what is the information that sufficie...

Stochastisches Verfahren zur Simulation von Breitbandschall in Triebwerkfans

Wohlbrandt, Attila (2017)

Die vorliegende Arbeit beschäftigt sich mit der Anwendung des Random-Particle-Mesh-Verfahrens (RPM) zur Simulation von Fanbreitbandschall. Aus zeitgemittelten, turbulenten Größen erzeugt das Verfahren zeitabhängige Fluktuationen, die zur Vorhersage der Schallentstehung hinreichend sind. Es wird isotrope, freie Turbulenz in Form von divergenzfreien Geschwindigkeitsfluktuationen synthetisiert. D...

Flashback prevention in lean-premixed hydrogen combustion

Reichel, Thoralf G. (2017)

The focus of this study is the combustion of hydrogen in air as it relates to typical gas turbine engines. Hydrogen–air combustion occurs in the absence of any carbon-based emissions and the only combustion products are water vapor and oxides of nitrogen (NOx). However, due to the very low flammability limit of hydrogen, it can be burned at much lower equivalence ratios than typical hydrocarbon...

Gefäßsteifigkeitsmessung als Screening-Verfahren zur verbesserten Beurteilung des kardiovaskulären Risikos

Karczewski, Tina (2017)

In 2003 the ESH/ESC recommended the arterial stiffness measurement for arterial hypertension management in their guidelines for the first time. In addition to the conventional blood pressure measurement, the clinicians are advised to measure following parameters: pulse wave velocity (PWV), augmentation pressure (AugP) and central blood pressure (zBD). A change in shape of the blood pressure wav...

Coupling of continuum mechanics and electrodynamics

Reich, Felix Alexander (2017)

In the literature, many models of electromagnetic momentum are proposed. Each model implies a form of the electromagnetic force density, which acts as a source in the mechanical momentum balance. The debate as to which model of the electromagnetic force is "correct" for arbitrary materials and processes is ongoing. Most authors argue in favor or against specific models by virtue of thought expe...

Standardised documentation of instrument use during laparoscopic surgery

Zickerow, Matthias ; Holmer, Christoph ; Kraft, Marc (2013)

To date, usability problems for laparoscopic instruments have mainly been investigated using questionnaires or laboratory studies. However, this methodology prevents the duration and frequency of instrument use from being documented objectively. Therefore, a tablet was used to create a graphic user interface which enables instrument use by operating and assisting surgeons to be documented with ...

A mobile gait analysis system for optimization of prosthetic alignments

Westebbe, Bettina ; Thiele, Julius ; Kraft, Marc (2013)

The prosthesis alignment is of central importance for a harmonic gait, especially for upper limb amputees. Today alignment optimization is based on static measuring and the experience of the orthopaedic technician. To objectify the alignment process a mobile gait analysis system based on 10 inertial sensors and a 6 DOF force and moment sensor was developed at the TU Berlin. The dedicated softwa...

Ergonomic problems originating in the use of high-frequency and ultrasonic medical devices

von Saucken, Anna-Maria ; Donner, Sylvia ; Kraft, Marc (2012)

High-frequency and ultrasonic medical devices are widely used in laparoscopic surgical procedures. Using these devices can result in ergonomic problems. Two studies were performed: in a questionnaire surgeons were asked to evaluate laparoscopic surgical instruments. Based on the resulting 74 data sets it was possible to define various improvements to the design of instruments. In a subsequent f...