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- Fakultät Betriebswirtschaft und Wirtschaftsingenieurwesen (B+W) (65) (remove)
This paper describes the concept and some results of the project "Menschen Lernen Maschinelles Lernen" (Humans Learn Machine Learning, ML2) of the University of Applied Sciences Offenburg. It brings together students ofdifferent courses of study and practitioners from companies on the subject of Machine Learning. A mixture of blended learning and practical projects ensures atight coupling of machine learning theory and application. The paper details thephases of ML2 and mentions two successful example projects.
Medical devices accompany our everyday life and come across in situations of worse condition, in significant moments concerning the health or during routine checkups. To ensure flawless operations and error-free results it is essential to test applications and devices. High risks for patient’s health come with operating errors [33] so that the presented research project, called Professional UX, identifies signals and irritations caused by the interaction with a certain device by analyzing mimic, voice and eye tracking data during user experience tests. Besides, this paper will provide information on typical errors of interactive applications which are based on an empirical lab-based survey and the evaluated results achieved. The pictured proceeding of user experience tests and the following analysis can also be applied to other fields and serves as a support for the optimization of products and systems.
A novel Bluetooth Low Energy advertising scan algorithm is presented for hybrid radios that are additionally capable to measure energy on Bluetooth channels, e.g. as they would need to be compliant with IEEE 802.15.4. Scanners applying this algorithm can achieve a low latency whilst consuming only a fraction of the power that existing mechanisms can achieve at a similar latency. Furthermore, the power consumption can scale with the incoming network traffic and in contrast to the existing mechanisms, scanners can operate without any frame loss given ideal network conditions. The algorithm does not require any changes to advertisers, hence, stays compatible with existing devices. Performance evaluated via simulation and experiments on real hardware shows a 37 percent lower power consumption compared to the best existing scan setting while even achieving a slightly lower latency which proves that this algorithm can be used to improve the quality of service of connection-less Bluetooth communication or reduce the connection establishment time of connection-oriented communication.
Direct Digital Manufacturing of Architectural Models using Binder Jetting and Polyjet Modeling
(2019)
Besides of conventional CAD systems, new, cloud-based CAD systems have also been available for some years. These CAD systems designed according to the principle of software as a service (SaaS) differ in some important features from the conventional CAD systems. Thus, these CAD systems are operated via a browser and it is not necessary to install the software on a computer. The CAD-data is stored in the cloud and not on a local computer or central server. This new approach should also facilitate the sharing and management of data. Finally, many of these new CAD systems are available as freeware for education purposes, so the universities can save license costs. This contribution examines newly developed, cloud-based CAD systems. In the context of a case study, the application of these new CAD systems are investigated in the training of engineers in design education. Thus, the students compare a conventional and a cloud-based CAD system as part of an exercise of designing and 3D modelling of a pinion shaft. Subsequently, the students manufacture a drawing with different views of the pinion shaft. This assessment evaluates different criteria such as user-friendliness, tutorial support and installation effort.
The development of new processes and materials for additive manufacturing is currently progressing rapidly. In order to use the advantages of additive manufacturing, however, product development and design must also be adapted to these new processes. Therefore it is suitable to use structural optimization. To achieve the best results in lightweight design, it is important to have an approach that reduces the volume in the unloaded regions and considers the restrictions and characteristics of the additive manufacturing process. In this contribution, a case study using a humanoid robot is presented. Thus, the pelvis module of a humanoid robot is optimized regarding its weight and stiffness. Furthermore, an integrated design is implemented in order to reduce the number of parts and the screw connections. The manufacturing uses a new aluminum-based material that has been specially developed for use in additive manufacturing and lightweight construction. For the additive manufacturing by means of the Selective Laser Melting (SLM) process, different restrictions and the assembly concepts of the humanoid robot have to be taken into account. These restrictions have to be considered in the setting of the individual parameters and target functions of the structural optimization. As a result, a framework is presented that shows the steps of the redesign and the optimization of the pelvis module. In order to achieve high accuracy with the product, the redesign of the pelvis module is demonstrated with regard to mechanical and thermal postprocessing. Finally, the redesigned part and the different assembly concepts are compared to analyze the economic and technical effects of the optimization.
The additive manufacturing processes have developed significantly in recent years. Currently, new generative processes are coming onto the market. Likewise, the number of available materials that can be processed using additive processes is steadily increasing. Therefore, an important task is to integrate these new processes and materials into the university education of engineers. Due to the rapid change and the constant development in the field of additive manufacturing, a pure transfer of knowledge is not expedient, because this obsolete very quickly. Rather, the students should be enabled to use their skills in such a way that they can always handle new technologies and materials independently and meaningfully.
In this paper, therefore, a new course is developed in which the students largely independently work with additive manufacturing processes. For this purpose, teams of four to five students from different technical programs are formed. The teams have the task of developing and manufacturing a product using additive processes. The goal is to create a powerful product by taking into account the optimization of costs and use of resources.
As an example, the development and additive manufacturing of an ornithopter (aircraft that flies by flapping its wings) will be presented in this contribution. The students have to analyze and optimize the mechanics and aerodynamics of the aircraft. In addition, the rules for production-oriented design must be determined and applied. Further more, they should assess the costs and material consumption during development and production.
This contribution shows how the students have achieved the different learning outcomes. In addition, it becomes clear how the students independently acquired and applied their knowledge in development, design and additive manufacturing. Also, it will be demonstrated how much time the students spent on learning the different technologies.
Avoiding collisions between a robot arm and any obstacle in its path is essential to human-robot collaboration. Multiple systems are available that can detect obstacles in the robot's way prior and subsequent to a collision. The systems work well in different areas surrounding the robot. One area that is difficult to handle is the area that is hidden by the robot arm. This paper focuses on pick and place maneuvers, especially on obstacle detection in between the robot arm and the table that robot is located on. It introduces the use of single pixel time-of-flight sensors to detect obstacles directly from the robot arm. The proposed approach reduces the complexity of the problem by locking axes of the robot that are not needed for the pick and place movement. The comparison of simulated results and laboratory measurements show concordance.
Top-level staff prefers to live in urban areas with perfect social infrastructure. This is a common problem for excellent companies (“hidden champions”) in rural areas: even if they can provide the services qualified applicants appreciate for daily living, they fail to attract them because important facts are not presented sufficiently in social media or on the corporate website. This is especially true for applicants with families. The contribution of this paper is four-fold: we provide an overview of the current state of online recruiting activities of hidden champions (1). Based on this corpus, we describe the applicant service gap for company information in rural communes (2). A study on user experience (UX) identifies the applicants’ wishes and needs, focusing on a family-oriented information system on living conditions in rural areas (3). Finally, we present the results of an online survey on the value of such information systems with more than 200 participants (4).
A car is only useful, when it runs properly – but keeping a car it running is getting more and more complex. Car service providers need a deep knowledge about technical details of the different car models. On the other hand car producers try to keep this information in their ownership. Digital data collection takes place every second on the car´s product life cycle and is stored on the car producers´ servers. The contribution of this paper is three-fold: we will provide an overview of the current concepts of intelligent order assistant technologies (I). This corpus is used to come to a more precise description of the specific service performance aspects (II). Finally, a representative empirical study with German motor mechanics will help to evaluate the wishes and needs regarding an intelligent order assistant in the garage (III).
Es wird eine Fallstudie vorgestellt, die die Visualisierung von Geschäftsdaten nach dem International Business Communication Standard IBCS (Hichert & Faisst 2016 / 2017) auf der cloudbasierten Plattform SAP Analytics Cloud umsetzt. Mit der Fallstudie soll die Frage beantwortet werden, ob IBCS im Rahmen einer Lehreinheit mit hohem praktischem Anteil mit SAP Analytics Cloud umgesetzt werden kann. Darüber hinaus soll der generelle Einsatz von SAP Analytics Cloud für die Lehre im Analytics-Umfeld evaluiert werden.
Existing ultrasonic stress evaluation methods utilize the acoustoelastic effect for bulk waves propagating in volume, which is unsuitable for a surface treated material, possessing a significant variation in material properties with depth. With knowledge of nonlinear elastic parameters – third-order elastic constants (TOEC) close to the surface of the sample, the acoustoelastic effect might be used with surface acoustic waves. This work is focused on the development of an independent method of TOEC measurement using the effect of nonlinear surface acoustic waves scattering – i.e. the effect of elastic waves interaction in a nonlinear medium.
In this paper, the possible three wave interactions of surface guided waves and bulk waves are described and formulae for the efficiency of harmonic generation and mode mixing are derived. A comparison of the efficiency of surface waves scattering in an isotropic medium for different interaction types is carried out with the help of nonlinear perturbation theory. First results for surface and bulk wave mixing with known second- and third-order elastic constants are shown.
Implementation of interdisciplinary student teams in design education for additive manufacturing
(2018)
Additive manufacturing (AM) technologies are becoming increasingly popular in all areas of product development. Therefore, it is imperative that students be taught Design for AM. However, due to the rapid development of new methods and materials for AM, it does not make sense to only teach particular design guidelines, as these can quickly become obsolete. Rather, students should acquire the competence to develop guidelines themselves, that take into account the current state of the art. Thus, they will be able to react to changing processes and new materials
in the future. In order to convey the independent development of design guidelines for additive manufacturing by students, a new concept was developed, which is presented in this contribution. In this process, the learning goal is worked out by a group of students on the basis of a practical
task. The group consists of an interdisciplinary team in order to combine different competencies and to provide different perspectives on the task. A case study will show the design and manufacture of a miniature aircraft using Fused Layer Modelling. The aim of the development is above all the design for additive manufacturing. In addition, a low use of resources in combination with lightweight construction should be achieved. In the implementation of the task, the students are confronted with challenging aerodynamic design of wings as well as with the economic evaluation of the development process. An examination of the level of knowledge before and after the case study examines the learning success.
We present a novel approach that utilizes BLE packets sent from generic BLE capable radios to synthesize an FSK-(like) addressable wake-up packet. A wake-up receiver system was developed from off-the-shelf components to detect these packets. It makes use of two differential signal paths separated by passive band-pass filters. After the rectification of each channel a differential amplifier compares the signals and the resulting wake-up signal is evaluated by an AS3933 wake-up receiver IC. Overall, the combination of these techniques contributes to a BLE compatible wake-up system which is more robust than traditional OOK wake-up systems. Thus, increasing wake-up range, while still maintaining a low energy budget. The proof-of-concept setup achieved a sensitivity of -47.8 dBm at a power consumption of 18.5 uW during passive listening. The system has a latency of 31.8 ms with a symbol rate of 1437 Baud.
Human-robot collaboration plays a strong role in industrial production processes. The ISO/TS 15066 defines four different methods of collaboration between humans and robots. So far, there was no robotic system available that incorporates all four collaboration methods at once. Especially for the speed and separation monitoring, there was no sensor system available that can easily be attached directly to an off-the-shelf industrial robot arm and that is capable of detecting obstacles in distances from a few millimeters up to five meters. This paper presented first results of using a 3D time-of-flight camera directly on an industrial robot arm for obstacle detection in human-robot collaboration. We attached a Visionary-T camera from SICK to the flange of a KUKA LBR iiwa 7 R800. With Matlab, we evaluated the pictures and found that it works very well for detecting obstacles in a distance range starting from 0.5 m and up to 5 m.
Die Erstellung und der Einsatz digitaler Medien basieren häufig auf der Annahme eines idealtypischen Lernprozesses, welcher die effektive Erarbeitung von Inhalten unter Berücksichtigung individueller Vorkenntnisse und Lebensumstände ermöglicht. Erfahrungen Lehrender legen jedoch die Vermutung nahe, dass Studierende selten ein idealtypisches Lernverhalten an den Tag legen. Für den Beitrag „Nutzungsmuster bei digitalen Medien“ wurden Forschungsarbeiten zu digitalen instruktionalen Medien gezielt ausgewertet, um die tatsächlichen Verhaltensweisen beim Lernen und die hiermit verbundenen Wirkungen aufzuzeigen. Aufbauend auf den Erkenntnissen soll eine Diskussion um mögliche Folgerungen für die Lehre angeregt werden.
Conversion-Killer in Onlineshops - Identifikation von Kundenorientierung anhand von Mimikindikatoren
(2018)
Zerstörungsfreie Verfahren zur Messung von Eigenspannungen
erfordern, abhängig vom gewählten Verfahren, die Kenntnis gewisser
Kopplungskonstanten. Im Falle von Ultraschallmessverfahren sind das neben den
elastischen Konstanten zweiter Ordnung (SOEC) vor allem die Konstanten dritter
Ordnung (TOEC). Elastische Konstanten fester, metallischer Bauteile werden in der
Regel in Zugversuchen bestimmt. Zur Ermittlung der TOEC werden diese mit
Ultraschallmessmethoden kombiniert. Durch äußere Einflüsse, wie etwa mechanische
Nachbehandlungen der zu untersuchenden Bauteile können sich diese Konstanten
jedoch ändern und müssen folglich direkt am veränderten Material bestimmt werden.
Mithilfe von Simulationen wird die Ausbreitung der zweiten Harmonischen und
der nichtlinear erzeugten Oberflächenwellen in Wellenmischexperimenten analysiert
und der akustische Nichtlinearitätsparameter (ANP) bzw. der Kopplungsparameter
aus der Amplitudenentwicklung berechnet. Insbesondere wird untersucht, welchen
Einfluss ein gegebenes Tiefenprofil der TOEC auf den ANP hat (Vorwärtsproblem)
und inwiefern sich aus den Messungen des ANP auf ein vorliegendes Tiefenprofil der
TOEC schließen lässt (inverses Problem). Außerdem wird diskutiert, welchen
Einfluss lokale Änderungen der SOEC auf den ANP haben können und wie groß diese
Änderungen sein dürfen, um die TOEC dennoch bestimmen zu können. Die
Untersuchungen hierzu wurden auf der Basis eines 3D-FEM Modells mit zufällig
orientierten Mikrorissen durchgeführt. Die numerischen Rechnungen zeigen dabei
auch eine gute Übereinstimmung mit einem aus der Literatur bekannten und für dieses
Problem erweiterten, analytischen Modell. Neben der rissinduzierten Nichtlinearität
kann bei diesem auch die Gitternichtlinearität berücksichtigt werden.
Elastic constants of components are usually determined by tensile tests in combination with ultrasonic
experiments. However, these properties may change due to e.g. mechanical treatments or service conditions during
their lifetime. Knowledge of the actual material parameters is key to the determination of quantities like residual
stresses present in the medium. In this work the acoustic nonlinearity parameter (ANP) for surface acoustic waves is
examined through the derivation of an evolution equation for the amplitude of the second harmonic. Given a certain
depth profile of the third-order elastic constants, the dependence of the ANP with respect to the input frequency is
determined and on the basis of these results, an appropriate inversion method is developed. This method is intended
for the extraction of the depth dependence of the third-order elastic constants of the material from second-harmonic
generation and guided wave mixing experiments, assuming that the change in the linear Rayleigh wave velocity is
small. The latter assumption is supported by a 3D-FEM model study of a medium with randomly distributed microcracks as well as theoretical works on this topic in the literature.
Implementation of lightweight design in the product development process of unmanned aerial vehicles
(2017)
In safety critical applications wireless technologies are not widely spread. This is mainly due to reliability and latency requirements. In this paper a new wireless architecture is presented which will allow for customizing the latency and reliability for every single participant within the network. The architecture allows for building up a network of inhomogeneous participants with different reliability and latency requirements. The used TDMA scheme with TDD as duplex method is acting gentle on resources. Therefore participants with different processing and energy resources are able to participate.
In medical applications wireless technologies are not widely spread. Today they are mainly used in non latency-critical applications where reliability can be guaranteed through retransmission protocols and error correction mechanisms. By using retransmission protocols within the disturbed shared wireless channel latency will increase. Therefore retransmission protocols are not sufficient for removing latency-critical wired connections within operating rooms such as foot switches. Todays research aims to improve reliability through the physical characteristics of the wireless channel by using diversity methods and more robust modulation. In this paper an Architecture for building up a reliable network is presented. The Architecture offers the possibility for devices with different reliability, latency and energy consumption requirements to participate. Furthermore reliability, latency and energy consumption are scalable for every single participant.
Sichere Detektion von Menschen in der Mensch-Roboter-Kollaboration mit Time-of-Flight Kameras
(2017)
First year Business Administration students tend to regard themselves as “non-computer scientists” and often have a lack of motivation about taking IT courses in general, either because they perceive them as too technical, too difficult or somewhat irrelevant. In an attempt to counteract this perception and increase the levels of engagement and willing attendance to class, we decided to flip the traditional lecture model and develop a new teaching and learning approach for the IT Fundamentals course using an open source Enterprise Resource Planning (ERP) system as the platform from which to draw the various underlying IT concepts and through which the relevant competences can be acquired.
This paper describes the implementation process of this new contextualized learning framework “IT via ERP” and the changes in the didactical methods to support it.
The paper recommends an approach to estimate effectively the probability of buffer overflow in high-speed communication networks, capable of carrying diverse traffic, including self-similar teletraffic, and supporting diverse levels of quality of service. Simulations with stochastic, long-range dependent self-similar traffic source models are conducted. A new efficient algorithm, based on a variant of the RESTART/LRE method, is developed and applied to accelerate the buffer overflow simulation in a finite buffer single server model under long-range dependent self-similar traffic load with different buffer sizes. Numerical examples and simulation results are shown
In a recent paper it has been shown that the effective nonlinear constant which is used in a P-Matrix approach to describe third-order intermodulation (IMD3) in surface acoustic wave (SAW) devices can be obtained from finite element (FEM) calculations of a periodic cell using nonlinear tensor data [1]. In this paper we extend this FEM calculation and show that the IMD3 of an infinite periodic array of electrodes on a piezoelectric substrate can be directly simulated in the sagittal plane. This direct approach opens the way for a FEM based simulation of nonlinearities for finite and generalized structures avoiding the simplifications of phenomenological approaches.
Einsatz von Additive Manufacturing zur Darstellung von Simulationsergebnissen in der Blechumformung
(2016)
Virtuelle Modell "begreifbar" Machen - Darstellung von Simulationsergebnissen mittels 3D-Farbdruck
(2016)
Additive Manufacturing of High-Strength components using impregnated polymer plaster composites
(2015)
Surface and interface acoustic waves are two-dimensionally guided waves, as their displacement field is plane-wave like regarding its dependence on the spatial coordinates parallel to the guiding plane, while it decays exponentially along the axis normal to that plane. When propagating at the planar surface or interface of homogeneous media, they are non-dispersive. Another type of non-dispersive acoustic waves which is, however, one-dimensionally guided, has displacement fields localized near the apex of a wedge made of an elastic material. In this short review, their propagation properties are described as well as theoretical and experimental methods which have been used for their analysis. Experimental findings are discussed in comparison with corresponding theoretical work and potential applications of this fascinating type of acoustic waves are presented.