FSP2: Mobilität
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CSNNs: Unsupervised, Backpropagation-free Convolutional Neural Networks for Representation Learning
(2019)
This work combines Convolutional Neural Networks (CNNs), clustering via Self-Organizing Maps (SOMs) and Hebbian Learning to propose the building blocks of Convolutional Self-Organizing Neural Networks (CSNNs), which learn representations in an unsupervised and Backpropagation-free manner. Our approach replaces the learning of traditional convolutional layers from CNNs with the competitive learning procedure of SOMs and simultaneously learns local masks between those layers with separate Hebbian-like learning rules to overcome the problem of disentangling factors of variation when filters are learned through clustering. We investigate the learned representation by designing two simple models with our building blocks, achieving comparable performance to many methods which use Backpropagation, while we reach comparable performance on Cifar10 and give baseline performances on Cifar100, Tiny ImageNet and a small subset of ImageNet for Backpropagation-free methods.
In the paper at hand, the simultaneous computation of fuel-minimal approach trajectories for multiple aircraft present in the vicinity of an airport at a certain point in time is treated. The trajectory optimization task includes the determination of the optimal aircraft queuing sequence on the ILS glide path, minimizing the total fuel consumption of all aircraft involved. The trajectory optimization is based on aircraft point-mass simulation models with the aircraft characteristics taken from the BADA database of EUROCONTROL. Specifically tailored path constraints are introduced that define the permitted airspace and that enforce the aircraft to follow the ILS glide path once they have passed the final approach fix. Furthermore, path constraints are implemented that guarantee certain separation distances between the involved aircraft throughout the approach flights. An algorithmic procedure is set up which is aimed at producing a good initial guess for the multi-aircraft trajectory optimization task. The proposed framework is applied to a generic scenario where a fuel-efficient approach scheduling for four civil passenger aircraft has to be determined.
This paper addresses the analysis of aircraft control capabilities during the cruise phase (flying at the established level with practically constant configuration and speed) in the presence of windshears. The study uses a point-mass aircraft model describing flight in a vertical plane. The problem is formulated as a differential game against wind disturbances. The first player, autopilot, controls the angle of attack and the power setting, whereas the second player, wind, produces dangerous gusts. The state variables of the model are subjected to constraints expressing aircraft safety conditions. Namely, the altitude, path inclination, and velocity are constrained. Viability theory is used to find the so-called viability kernel, the maximal subset of the state constraint where the aircraft trajectories can remain arbitrary long if the first player utilizes an appropriate feedback control, and the second player generates any admissible disturbances. The computations are based on grid methods developed by the authors and implemented on a multiprocessor computer system.
This study introduces an approach to decrease the electric energy consumption by efficient guidance of a battery-electrically propulsed airplane. An appropriate mathematical model containing a detailed energy consumption estimation is presented. With this, an optimal control problem is formulated and solved using the MATLAB Toolbox FALCON.m. Furthermore, steady state efficiency criteria are established for a range optimal climb and a horizontal flight. With the help of steady state grid calculation, values for both efficiency criteria and corresponding guidance parameters are determined. The optimal values of both criteria are correlated with the steady state arcs of the optimal trajectory. For the descend segment, an optimal airspeed is determined and correlated also with the trajectory. As a result, energy optimal steady state guidance parameters can be provided to the pilot for each flight segment. A concept of a cockpit display is introduced that delivers efficient guidance parameters to the pilot.
Die assistierte Querführung wie das Spurhalteassistenzsystem ist ein Schlüssel zur erfolgreichen Einführung des hochautomatisierten Fahrens. Was empfindet der Kunde beim Einsatz von Spurhalteassistenzsystemen, und welche psychischen und physischen Belastungen lösen die verschiedenen Fahrsituationen aus? Welche Erwartungen hat er an das Fahrerlebnis? Was wird als angenehm und unangenehm empfunden, was wird akzeptiert, und welche Attribute sind inakzeptabel? Die Hochschule Kempten und MdynamiX sind diesen Fragen in breit angelegten Studien mit insgesamt 120 Probanden im Realeinsatz nachgegangen.
Eine der größten Barrieren der heutigen Elektrofahrzeuge ist ihre limitierte Reichweite. Obwohl die Mehrheit der Autofahrer nicht mehr als 40 Kilometer pro Tag fährt ([MiD2008]), ist das Kaufverhalten für Elektrofahrzeuge mit viel kleinerer Reichweite als solcher mit Verbrennungsmotoren sehr zurückhaltend. Mit dieser Arbeit adressieren wir die zusätzlichen Informationsbedürfnisse der Fahrer von E-Fahrzeugen durch die Entwicklung einer Applikation für Standard-Smartphones, welche sowohl eine detaillierte und genaue grafische Repräsentation der Reichweite des Elektrofahrzeugs ermöglicht, als auch einen fortgeschrittenen Routing-Algorithmus implementiert, der den spezifischen Energieverbrauch des Elektrofahrzeugs berücksichtigt.
Occluding Edges Soft Shadows
(2016)
In this paper, a new algorithm to render soft shadows in real time applications is introduced, namely the Occluding Edges Soft Shadow algorithm (short OESS). The algorithm approximates the shadow cast from linear lights by finding the outlines of an occluding object (Occluding Edges) and considering these in a fragment’s illumination. The method is based on the shadow mapping technique, whereby its capability of rendering the shadow at an interactive rate does not depend on the complexity of the scene. The paper supplies an overview for several methods to produce shadows and soft shadows in real time computer graphics, a detailed description of the newly developed algorithm, and a section with results and future possibilities for improvements.
The project IDA - Intelligent Data Acquisition is an interdisciplinary project in the fields of applied informatics and mechanical engineering. Its purpose is to collect process relevant information in industrial foundry processes like iron casting with handmade and mechanically made molds. Currently a lot of data sets are collected by hand. But these contain inaccuracies and errors and are not available digitally for further analysis. As a result it is not possible to evaluate them automatically. In particular it is not possible to conclude from a defect cast part to the whole set of its production parameters. We develop several procedures to collect these data sets and prepare them for computation in data analysis algorithms. The acquisition of digitally available data in IDA is done mostly by optical sensors. In this paper we describe our approach especially regarding marking and recognition of relevant objects. Furthermore we show first results in environments close to reality.
In inductive power transfer systems a smooth variation of input power can be achieved by using a controlled rectifier. The power can be changed by varying the fundamental amplitude of the primary and secondary voltages along with the phase angle between them. The paper shows how the input power is controlled and under what circumstances Zero Voltage Switching (ZVS) is lost on primary and secondary side of the system.
This paper presents a 4 kVA single-phase isolated (230V/230V) ac/ac Dual Active Bridge (DAB) converter prototype suitable for Solid State Transformer (SST) applications. A solution for inductive load is introduced and a novel control scheme based on gain scheduling approach is employed to improve the DAB overall efficiency. Efficiency optimization is done based on global Zero-Voltage Switching (ZVS) analysis of the DAB converter operating range for dual phase-shift modulation. In this analysis, minimization of both the Reactive Power per Switching Cycle (RPSC) and the rms current of the high frequency inductance is taken into consideration to get the optimal modulation parameters. Simulation results are presented to validate the proposed control scheme.
Active phase shifting method incorporates change in phase and amplitude of fundamental primary inverter output and secondary rectifier input voltages of a resonant DC/DC converter. This paper
presents implementation of this method on four basic topologies of resonant tank configurations or
compensation circuits of a resonant converter. Smooth variation of input power along with Zero Voltage Switching (ZVS) regions both on primary and secondary side have been observed for different configurations. Equations for input power as a function of the phase angles, switching
frequency, input and output voltage amplitudes and the values of the reactive components have been derived. The results are verified with simulations of all the configurations and practical setup for one of the best configuration for IPT systems.
Piezomaterialien finden in der Mikrosystemtechnik ein breites Anwendungsspektrum. Die Machbarkeitsstudie untersucht die Möglichkeiten Piezoplatten in den Herstellungsprozess von modernen Leiterplatten-Multilayer zu integrieren. Die glasfaserverstärkte Epoxidstruktur des PCBs wirkt zum einen als Träger für die spröde Piezokeramik. Des Weiteren kann durch die internen Leiterbahnen eine Kontaktierung der Keramik realisiert werden. Im Vorfeld wurden der Lagenaufbau sowie geometrischen Voraussetzungen für eine Verbindung mittels Lotpaste experimentell überprüft. Als Anwendungsbeispiel wird ein Vibrations-Harvesters aufgebaut und getestet. Die maximale Leistung des Harvesters liegt bei 7,86 mW mit einer Eingangsbeschleunigung von 4g. Der positive Funktionstest demonstriert die grundsätzliche Anwendbarkeit des Ansatzes, auch wenn die elektrische Kontaktierung mittels Lotpaste kritisch zu bewerten ist.
Bells are musical instruments exposed to severe loading and stress conditions during ringing. The impact of the clapper leads to local wear with material abrasion and high stresses with possible fatigue cracks. Such damages may only be identified based on tone shifts and increased damping, when they have already propagated to large dimensions. Consequently repair such as welding or even re-casting become necessary. Here procedures for the fatigue life evaluation of bells are presented based on investigations of at least more than 300 culturally and historically important bells in Europe.
From those investigations the most important conclusion is, that each bell is unique in its structure and its setup for ringing and has to be evaluated individually. Thus recent research aimed on a very early crack detection. Then changes of the sound are still very small, so that the musical quality of the bell may not be impaired.
Then still measures can be taken to stop the crack propagation at this early stage without severe repair and the bell continues to ring. Recent research concentrates on the design of the sound of the bell based on the parameters by which the bell setup is defined and the stress conditions are determined.
KEYWORDS
BELL, RINGING, SOUND, FATIGUE CRACK, WEAR, LOADING, SIMULATION,
MEASUREMENT, MONITORING
There is a method for deterministically detecting a license plate, which is one of the object detections in autonomous driving. It is difficult to determine a luminance threshold value used for binarization. Therefore, the method of predicting the threshold value by machine learning from the combination of surrounding luminances has been improved. First, we constructed an augmentation that extends the objective variable from the structure of the labeled data, and increased the number of the original data by about 50 times. Next, we devised a new method to prevent overestimation of the cross-validation method. After Augmentation, we developed a Leave A Group Out Cross-Validation method that separates training data and test data in groups. By combining the performance improvement by the configured Augmentation and the improvement by the conventional SMOTE, a detection rate of 0.92 was achieved. As a result, the autonomous driving module has been strengthened by one step.
Bewege mich!
(2019)
Church bells are exposed to severe loading conditions during ringing, which results in different damage modes due to material wear, fatigue loading, material deficiencies, different clapper-to-bell layouts, etc. As part of the activities of an EU-funded project called Maintenance and Protection of Bells (PROBELL), experimental investigations and finite-element simulations of the local contact between the clapper and the bell were carried out to study the wear-related damage to bells. First a simplified model was built to assess under the laboratory-controlled conditions the consequences of the repetitive impacts between a spherical body made from steel and a flat block made from bronze. After the results of the finite-element simulations for a simplified model were in reasonable agreement with the measured data a full-scale finite-element model for simulating the repetitive clapper-to-bell strokes was built. The simulations with the full-scale model were performed for variations of the parameters that influence the structural behaviour of the bell and the clapper: the clapper material, the clapper mass, the relative impact velocity of the clapper, the shape of the clapper, the clapper's pin support, the clapper's impact angle, the clapper's guide accuracy, the bell's sound-burp thickness and the coefficient of friction between the clapper and the bell. The agreement between the simulated and the measured results and the relation between the local stress–strain state and the damage to the bell in the contact area are discussed.
Porosity distribution in laser-sintered polymeric thin sheets as revealed by X-ray micro tomography
(2019)
Laser Sintering (LS) is an additive manufacturing technology that is progressively used to manufacture functional products for end-use applications. However, LS technology provides limited ability to produce thin-walled structures that feature high material quality. A key parameter determining the quality of LS polymeric parts is porosity. This article presents a new approach towards clarifying the porosity characteristics of thin-walled structures produced by LS. Therefore, thin sheets of different thickness built in different orientations within the building chamber are examined by means of X-ray micro tomography. The porosity analysis includes the overall porosity, pore number density, pore size distribution and porosity distribution along the thickness of the thin sheets. The results show that the porosity characteristics strongly depend on the thickness and the build orientation of the thin sheets. This investigation helps to estimate the quality of three dimensional hollow bodies produced by LS and moreover, contributes to a better understanding of the pore formation in LS processes.
As an alternative to conventional wind turbines, this study considered kites with onboard wind turbines driven by a high airspeed due to crosswind flight (“drag power”). The hypothesis of this study was, that if the kite's lift coefficient is maximized, then the power, energy yield, allowed costs and profit margin are also maximized. This hypothesis was confirmed based on a kite power system model extended from Loyd's model. The performance of small-scale and utility-scale kites in monoplane and biplane configurations were examined for increasing lift coefficients. Moreover, several parameters of the utility-scale system were optimized with a genetic algorithm. With an optimal lift coefficient of 4.5, the biplane outperformed the monoplane. A 40 m wing span kite was expected to achieve a rated power of about 4.1 MW with a power density of about 52 kW/m2. A parameter sensitivity analysis of the optimized design was performed. Moreover, to demonstrate the feasibility of very high lift coefficients and the validity of a utilized simplified airfoil polar model, CFDs of a proposed high-lift multi-element airfoil were performed and the airfoil polars were recorded. Finally, a planform design of a biplane kite was proposed.
Kamerabasierte Rückspiegel bieten das Potenzial, ein größeres Sichtfeld zu schaffen und rückwärtige Verkehrsinformationen besser anzuzeigen. Das Adrive Living Lab, eine Forschungseinrichtung der Hochschule Kempten, hat in Kooperation mit MdynamiX, einem An-Institut der Hochschule München, und Gentex eine Kundenakzeptanzuntersuchung sowie eine Feldstudie zu einem kamerabasierten Hybridspiegel durchgeführt. Dabei wurden die Nutzererfahrungen, die Nutzerakzeptanz und die Kundenwünsche im Bezug auf einen digitalen Rückspiegel im realen Straßenverkehr analysiert und ausgewertet.