Inst. Maschinenkonstruktion und Systemtechnik

179 Items

Recent Submissions
An end‐to‐end‐trainable iterative network architecture for accelerated radial multi‐coil 2D cine MR image reconstruction

Kofler, Andreas ; Haltmeier, Markus ; Schaeffter, Tobias ; Kolbitsch, Christoph (2021-04-01)

Purpose Iterative convolutional neural networks (CNNs) which resemble unrolled learned iterative schemes have shown to consistently deliver state‐of‐the‐art results for image reconstruction problems across different imaging modalities. However, because these methods include the forward model in the architecture, their applicability is often restricted to either relatively small reconstruction ...

Methodology for Estimating the Spatial and Temporal Power Demand of Private Electric Vehicles for an Entire Urban Region Using Open Data

Straub, Florian ; Streppel, Simon ; Göhlich, Dietmar (2021-04-08)

With continuous proliferation of private battery electric vehicles (BEVs) in urban regions, the demand for electrical energy and power is constantly increasing. Electrical grid infrastructure operators are facing the question of where and to what extent they need to expand their infrastructure in order to meet the additional demand. Therefore, the aim of this paper is to develop an activity-bas...

Estimating ventilation rates and emissions from a naturally ventilated dairy barn

Janke, David (2021)

Die Bestimmung von Luftwechselraten und Emissionen aus frei gelüfteten Tierhaltungssystemen ist mit großen Unsicherheiten behaftet. Das Ziel dieser Dissertation war die Untersuchung des Einfusses von Probenahmepositionen auf die Bestimmung von Luftwechselraten und Emissionen sowie die Optimierung und Weiterentwicklung derzeit angewandter Methoden. Dazu wurden drei methodische Ansätze in Form e...

Concept and Realization of a Novel Test Method Using a Dynamic Test Stand for Detecting Persons by Sensor Systems on Autonomous Agricultural Robotics

Meltebrink, Christian ; Ströer, Tom ; Wegmann, Benjamin ; Weltzien, Cornelia ; Ruckelshausen, Arno (2021-03-26)

As an essential part for the development of autonomous agricultural robotics, the functional safety of autonomous agricultural machines is largely based on the functionality and robustness of non-contact sensor systems for human protection. This article presents a new step in the development of autonomous agricultural machine with a concept and the realization of a novel test method using a dyn...

Measurement and Analysis of Inadequate Friction Mechanisms in Liquid-Buffered Mechanical Seals Utilizing Acoustic Emission Technique

Medina-Arenas, Manuel ; Sopp, Fabian ; Stolle, Johannes ; Schley, Matthias ; Kamieth, René ; Wassermann, Florian (2021-03-18)

Mechanical seals play an important role in the reliability of a process. Currently, the condition monitoring of mechanical seals is restricted due to the limitations of the traditional monitoring methods, including classical vibration analysis. For this reason, the objective of the present work is the detection and analysis of friction mechanisms inside a mechanical seal that are unfavorable an...

4D flow imaging with 2D spatially selective excitation

Wink, Clarissa (2021)

Magnetic resonance imaging is a versatile non-invasive imaging modality that allows complex hemodynamics to be measured three-directionally, temporally, and 3D spatially resolved by a technique called 4D flow imaging. The resulting velocity vector fields yield a variety of diagnostic parameters and physiological information. However, 4D flow imaging is still limited by long scan times, which hinde...

Agricultural Monitoring Using Polarimetric Decomposition Parameters of Sentinel-1 Data

Harfenmeister, Katharina ; Itzerott, Sibylle ; Weltzien, Cornelia ; Spengler, Daniel (2021-02-06)

The time series of synthetic aperture radar (SAR) data are commonly and successfully used to monitor the biophysical parameters of agricultural fields. Because, until now, mainly backscatter coefficients have been analysed, this study examines the potentials of entropy, anisotropy, and alpha angle derived from a dual-polarimetric decomposition of Sentinel-1 data to monitor crop development. The...

Adaptive sparsity level and dictionary size estimation for image reconstruction in accelerated 2D radial cine MRI

Pali, Marie‐Christine ; Schaeffter, Tobias ; Kolbitsch, Christoph ; Kofler, Andreas (2020-11-17)

Purpose In the past, dictionary learning (DL) and sparse coding (SC) have been proposed for the regularization of image reconstruction problems. The regularization is given by a sparse approximation of all image patches using a learned dictionary, that is, an overcomplete set of basis functions learned from data. Despite its competitiveness, DL and SC require the tuning of two essential hyperp...

3D Free‐breathing multichannel absolute B1+ Mapping in the human body at 7T

Dietrich, Sebastian ; Aigner, Christoph S. ; Kolbitsch, Christoph ; Mayer, Johannes ; Ludwig, Juliane ; Schmidt, Simon ; Schaeffter, Tobias ; Schmitter, Sebastian (2020-12-07)

Purpose To introduce and investigate a method for free‐breathing three‐dimensional (3D) B1+ mapping of the human body at ultrahigh field (UHF), which can be used to generate homogenous flip angle (FA) distributions in the human body at UHF. Methods A 3D relative B1+ mapping sequence with a radial phase‐encoding (RPE) k‐space trajectory was developed and applied in 11 healthy subjects at ...

Modeling and Experimental Investigation of Thermal Comfort and Energy Consumption in a Battery Electric Bus

Cigarini, Francesco ; Fay, Tu-Anh ; Artemenko, Nikolay ; Göhlich, Dietmar (2021-01-06)

In battery electric buses (e-buses), the substantial energy consumption of the heating, ventilation, and air conditioning (HVAC) system can cause significant reductions of the available travel range. Additionally, HVAC systems are often operated at higher levels than what required for the thermal comfort of the passengers. Therefore, this paper proposes a method to experimentally investigate th...

Untersuchung der Potentiale zur Modellierung von Walzasphalt mittels der Diskrete Elemente Methode

Müller, Dirk-Niklas (2021)

Der vorherrschende Wissensstand über die auftretenden Zusammenhänge beim Einbauprozesses und deren mathematische Beschreibung sind wissenschaftlich nicht sehr gut dokumentiert, was auf mehrere Gründe zurückzuführen ist. Als maßgebliche Gründe lassen sich folgende Ursachen identifizieren: Erstens ist die Tatsache zu nennen, dass der Großteil der Entwicklung bei Straßenfertigern auf Basis von Erf...

Sensorless force control for dielectric elastomer transducers

Hoffstadt, Thorben ; Maas, Jürgen (2019-05-01)

Multilayer stack-transducers made of dielectric elastomers generate considerable tensile forces and deformations when they are electrically stimulated. Thus, due to their capacitive behavior, they are for example energy efficient substitutes for conventional electromagnetic drives and enable various further completely new applications. Within this contribution, we present a sensorless force con...

Environmental Impact of Subsidy Concepts for Stimulating Car Sales in Germany

Scharf, Malte ; Heide, Ludger ; Grahle, Alexander ; Syré, Anne Magdalene ; Göhlich, Dietmar (2020-12-01)

In 2020, vehicle sales decreased dramatically due to the COVID-19 pandemic. Therefore, several voices have demanded a vehicle subsidy similar to the “environmental subsidy” in Germany in 2009. The ecological efficiency of vehicle subsidies is controversially discussed. This paper establishes a prognosis of the long-term environmental impacts of various car subsidy concepts. The CO2 emissions of...

Konzeption und Analyse einer magnetisch-elektrisch leistungsverzweigten Umlaufgetriebestufe zum Einsatz in einem landwirtschaftlichen Fahrzeug

Lang, Matthias (2020)

In landwirtschaftlichen Fahrzeugen haben sich in den letzten Jahren neben den manuellen Schaltgetrieben und den Lastschaltgetrieben auch die Stufenlosgetriebe etabliert. Diese ermöglichen eine Anpassung der Fahrzeuggeschwindigkeit unabhängig von der Drehzahl des Verbrennungsmotors und nutzen dafür üblicherweise ein kontrollierendes Element zur Drehzahlüberlagerung. Stand heute ist dieses kontro...

Designs and performance of three new microprocessor-controlled knee joints

Thiele, Julius ; Schöllig, Christina ; Bellmann, Malte ; Kraft, Marc (2018-02-09)

A crossover design study with a small group of subjects was used to evaluate the performance of three microprocessor-controlled exoprosthetic knee joints (MPKs): C-Leg 4, Plié 3 and Rheo Knee 3. Given that the mechanical designs and control algorithms of the joints determine the user outcome, the influence of these inherent differences on the functional characteristics was investigated in this ...

Entwicklung eines numerischen Modells zur Beschreibung von Gasfolienlagern unter Berücksichtigung der Temperatur

Michel, Hanns (2020)

In this dissertation a numerical model describing the properties of radial gas foil bearings under consideration of temperature is developed. For this purpose, the equilibrium position in which the external load and the force acting on the rotor resulting from the pressure field compensate each other is determined at constant load and speed. The results are utilized in combination with a pertur...

A Comprehensive TCO Evaluation Method for Electric Bus Systems Based on Discrete-Event Simulation Including Bus Scheduling and Charging Infrastructure Optimisation

Jefferies, Dominic ; Göhlich, Dietmar (2020-08-19)

Bus operators around the world are facing the transformation of their fleets from fossil-fuelled to electric buses. Two technologies prevail: Depot charging and opportunity charging at terminal stops. Total cost of ownership (TCO) is an important metric for the decision between the two technologies; however, most TCO studies for electric bus systems rely on generalised route data and simplifyin...

Methodology for Determining Charging Strategies for Freight Traffic Vehicles based on Traffic Simulation Results

Miranda Jahn, Ricardo ; Syré, Anne Magdalene ; Grahle, Alexander ; Martins-Turner, Kai ; Göhlich, Dietmar (2020-12-01)

The decarbonization of transport is one major challenge in the upcoming years. One possible solution is the use of battery electric vehicles (BEV). While electric passenger cars and their charging strategies are already in series production, battery electric trucks and their charging strategies are still mostly in the prototype stage. The range limitations of battery electric trucks represent a...

Modellierung und Regelung von dielektrischen Mehrschicht-Elastomerwandlern

Hoffstadt, Thorben (2019)

Electromechanical transducers based on dielectric elastomers (DE) can be operated as actuators, generators and sensors. Compared to classic electromagnetic actuators the intrinsic material properties offer significant advantageous e.g. concerning the energy efficiency and density enabling amongst others miniaturization potentials. Researching intelligent supply and control concepts, for example...

Design, Implementation, Evaluation and Application of a 32-Channel Radio Frequency Signal Generator for Thermal Magnetic Resonance Based Anti-Cancer Treatment

Han, Haopeng ; Eigentler, Thomas Wilhelm ; Wang, Shuailin ; Kretov, Egor ; Winter, Lukas ; Hoffmann, Werner ; Grass, Eckhard ; Niendorf, Thoralf (2020-06-28)

Thermal Magnetic Resonance (ThermalMR) leverages radio frequency (RF)-induced heating to examine the role of temperature in biological systems and disease. To advance RF heating with multi-channel RF antenna arrays and overcome the shortcomings of current RF signal sources, this work reports on a 32-channel modular signal generator (SGPLL). The SGPLL was designed around phase-locked loop (PLL) ...