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In this paper we discuss how group processes can be influenced by designing specific tools in computer supported collaborative leaning. We present the design of a shared workspace application for co-constructive tasks that is enriched by certain functions that are able to track, analyze and feed back parameters of collaboration to group members. Thereby our interdisciplinary approach is mainly based on an integrative methodology for analyzing collaboration behavior and patterns in an implicit manner combined with explicit surveyed data of group members’ attitudes and its immediate feedback to the groups. In an exploratory study we examined the influence of this feedback function. Although we could only analyze ad-hoc groups in this study, we detected some benefits of our methodology which might enrich real life Learning Communities’ collaboration processes. The data analysis in our study showed advantages of this feedback on processes of a group’s well-being as well as parameters of participation. These results provide a basis for further empirical work on problem solving groups that are supported by means of parallel interaction analysis as well as its re-use as information resource.
Resource Usage in Online Courses: Analyzing Learner’s Active and Passive Participation Patterns
(2015)
The paper analyzes the experience with an open university course for a very heterogeneous target group in which MOOC-like materials and activities were used. The course was conducted in a specifically prepared and extended Moodle environment. The analysis involves questionnaires as well as performance data that reflect the resource access on the learning platform. A special focus is put on the participants’ acceptance and usage of student-generated versus teacher-provided learning content. Network analysis techniques have been used to identify "interest clusters" of students around certain resources.
We present an architecture based on the Dynamic Field Theory for the problem of scene representation. At the core of this architecture are three-dimensional neural fields linking feature to spatial information. These three-dimensional fields are coupled to lower-dimensional fields that provide both a close link to the sensory surface and a close link to motor behavior. We highlight the updating mechanism of this architecture, both when a single object is selected and followed by the robot's head in smooth pursuit and in multi-item tracking when several items move simultaneously
Based on the concepts of dynamic field theory (DFT), we present an architecture that autonomously generates scene representations by controlling gaze and attention, creating visual objects in the foreground, tracking objects, reading them into working memory, and taking into account their visibility. At the core of this architecture are three-dimensional dynamic neural fields (DNFs) that link feature to spatial information. These three-dimensional fields couple into lower dimensional fields, which provide the links to the sensory surface and to the motor systems. We discuss how DNFs can be used as building blocks for cognitive architectures, characterize the critical bifurcations in DNFs, as well as the possible coupling structures among DNFs. In a series of robotic experiments, we demonstrate how the DNF architecture provides the core functionalities of a scene representation.
In this review, we describe current Machine Learning approaches to hand gesture recognition with depth data from time-of-flight sensors. In particular, we summarise the achievements on a line of research at the Computational Neuroscience laboratory at the Ruhr West University of Applied Sciences. Relating our results to the work of others in this field, we confirm that Convolutional Neural Networks and Long Short-Term Memory yield most reliable results. We investigated several sensor data fusion techniques in a deep learning framework and performed user studies to evaluate our system in practice. During our course of research, we gathered and published our data in a novel benchmark dataset (REHAP), containing over a million unique three-dimensional hand posture samples.
The continuous evolution of learning technologies combined with the changes within ubiquitous learning environments in which they operate result in dynamic and complex requirements that are challenging to meet. The fact that these systems evolve over time makes it difficult to adapt to the constant changing requirements. Existing approaches in the field of Technology Enhanced Learning (TEL) are generally not addressing those issues and they fail to adapt to those dynamic situations. In this chapter, we investigate the notion of an adaptive and adaptable architecture as a possible solution to address these challenges. We conduct a literature survey upon the state of the art and state of practice in this area. The outcomes of those efforts result in an initial model of a Domain-specific architecture to tackle the issues of adaptability and adaptiveness. To illustrate these ideas, we provide a number of scenarios where this architecture can be applied or is already applied. Our proposed approach serves as a foundation for addressing future ubiquitous learning applications where new technologies constantly emerge and new requirements evolve.
This paper discusses the efforts carried out related to the design and development of a web-based framework that allows designing, deploying and executing mobile data collecting applications. Furthermore, it also allows analyzing and presenting the data that is generated during the mentioned process. The fact that the framework is completely web-based provides a platform independent execution of the mobile application on any mobile device with a web-browser. As a result that the whole life-cycle of creating, executing and discussing a mobile learning activity is implemented in pure web-based manner separates this work from similar efforts. In the course of this work, the current state of development of two of the components, the authoring tool and the mobile application is presented. This framework was introduced to teachers in an activity to follow up an initial study. On the basis of a workshop with teachers, we performed an explorative study regarding the technology acceptance and usability of two components of the proposed framework. The results are discussed and analyzed in this paper.
This paper presents a web-based framework that allows the creation and deployment of mobile learning activities. We present an authoring tool that allows not-technically skilled persons to design mobile learning tasks and deploy them as a web-based mobile application. Since the presented approach is based exclusively on web-technologies, the deployed mobile application can be executed via a mobile browser and therefore is platform independent. Despite previous research efforts carried out in this domain, few of the projects have addressed this course of actions from a purely web-based perspective. Through the latest development of web technologies, mobile applications have access to internal sensors like camera, microphone and GPS and therefore allow data collection within web-applications. In order to validate whether the proposed framework can be applied in educational settings, we conducted a pilot study with experienced teachers and present the results of these efforts in this paper.
This paper describes the design and development stages of a web-based framework, aiming to support the creation of mobile applications within the context of mobile learning. The suggested approach offers the opportunity to deploy and execute these applications on mobile devices. This web-based solution additionally offers the possibility to visualize the data collected by the mobile applications in a web-browser. Despite previous research efforts carried out in this domain, few of the projects have addressed these processes from a purely web-based perspective. Currently, a prototype of an authoring tool for creating mobile data collection applications is already implemented. In order to integrate and validate this solution in everyday educational settings, we are collaborating with a network of high schools. On the basis of workshops with teachers we will carry out, refinements and requirements for further enhancements will be collected and will be used to guide our coming efforts.
Artificial intelligence (AI) is one of the most auspicious yet controversial technologies with virtually unlimited potential to solve almost all of the existential problems humanity is facing today.1 Huge resources are poured into the development, testing and application of AI that is supposed to be utilized in almost all areas of everyday life.2 It may be used to combat genetically inherited diseases, to revolutionize the economy, to bring prosperity and equality to everyone and to counter the effects of climate change.3 With AI as the enabling technology humanity may experience a better future. Today, AI capabilities can already drastically improve analytic processing tasks and algorithmic systems and have beaten humans in games such as chess.4 Yet, AI and all of its applications bring about a myriad of ethical challenges. Revolutionary weapon systems that achieve autonomy via AI and genome-editing powered by AI are just some specific examples.5 An omnipotent AI will be either the greatest or the vilest thing that has happened to humanity in its brief existence.6 However, even today more and more computational devices are connected to each other, spurring a huge increase in global data streams that can be used to further train and enhance AI systems.
The prowess of AI for executing analytic tasks paves the way for the use of AI in more and more applications. One of these applications, that shows great promise, is the use of AI in surveillance applications.7 AI surveillance applications are proliferating at a fast rate, with a number of appli-cations already being in use today.8 These applications are aimed at accomplishing a number of policy objectives, some are in accordance with basic human laws, some are definitely not and some
1 Cf. Hawking (2018). P. 183ff
2 Cf. Hawking (2018). P. 183ff.
3 Cf. Hawking (2018). P. 183ff.
4 Cf. Burton (2015). P. 1ff.
5 Cf. Hawking (2018). P. 183ff.
6 Cf. Hawking (2018). P. 183ff.
7 Cf. Feldstein (2019). P. 1.
8 Cf. Feldstein (2019). P. 1.
2
belong in the nebulous area in between lawful and unlawful.9 But what are lawful and unlawful uses of AI surveillance systems and what are their ethical implications?
This thesis will examine the ethical implications of AI based mass surveillance systems and try to answer the first central question, if it is possible to use AI based mass surveillance applica-tions in an ethical way. Furthermore, the thesis will attempt to answer the second central ques-tion and find out how the ethical use of AI based mass surveillance systems, if this ethical use is possible, materialize. Governmental agencies will be in the focus of this discussion, as their use of the technology may have bigger ethical challenges. Yet private companies will play a part as well. In an attempt to accomplish these two aims, the thesis will inspect the basics of ethics and possible ethical theories that can be utilized to answer the questions. Normative ethics will be stud-ied first with a focus on consequentialism and utilitarianism. To gain a deeper understanding of utilitarianism, act and rule utilitarianism will be compared. Afterwards, deontological theories will be the focus of the discussion with a concentration on deontological pluralism. Next, the mentioned theories will be evaluated, discussing advantages and weak spots of the theories, to assess which theory may serve as the ethical framework of this thesis and the subsequent answer to the two main questions.
The next step will be the establishment of the AI framework. This contains the definition of AI and a distinction of terms that are commonly used in the its environment such as automation and au-tonomy. The importance of data for AI will be discussed. Afterwards, the technological basis of AI will be outlined, discussing key concepts such as machine learning and deep learning. Addi-tionally, it will be examined how an AI learns. The possible uses of AI in general will be outlined in a brief fashion, blazing the trail to discussing the moral challenges of AI. Afterwards, the current pace of AI development will be studied.
In the chapter that follows, the use of AI in surveillance technology is going to be highlighted. The possible ways of how AI can be used for surveillance purposes are reviewed here, discussing facial
9 Cf. Feldstein (2019). P. 1.
3
and behavioral recognition systems, smart cities, smart policing, communications/data driven sur-veillance and their enabling technologies. Then, the global proliferation of AI surveillance systems is going to be outlined.
Subsequently, the accordance of AI surveillance with basic human laws and rights, such as the right to privacy, will be checked to find out if the law and the international framework of human rights allow for AI surveillance or at least have restrictions that would greenlight the use of AI surveillance technology. All the aspects of the thesis, especially including the selected ethical framework, will be combined in this last section in order to enable the adaptation of a framework that allows to find out, if AI surveillance systems can be ethically permissible while also creating insights how this ethical AI surveillance system must be engineered. To finish, the thesis will end with a conclusion.
For face recognition from video streams speed and accuracy are vital aspects. The first decision whether a preprocessed image region represents a human face or not is often made by a feed-forward neural network (NN), e.g. in the Viisage-FaceFINDER® video surveillance system. We describe the optimisation of such a NN by a hybrid algorithm combining evolutionary multi-objective optimisation (EMO) and gradient-based learning. The evolved solutions perform considerably faster than an expert-designed architecture without loss of accuracy. We compare an EMO and a single objective approach, both with online search strategy adaptation. It turns out that EMO is preferable to the single objective approach in several respects.
Methods of red-hot rod shape testing require a robust non-contact measurement principle as a touch point could lead to damages to the rod and the detection unit. Therefore a new basic approach based on high frequency eddy current (HFEC) has been investigated. Due to the robustness and the ability to determine the rod shape even above the Curie temperature this principle is especially well suited and can be implemented in the production process directly. The first automatic measurement setup was successfully developed with promising results. Hereby a defect of ovality was detected with a parallel RLC-oscillator. The capacity of this RLC-oscillator is constant whereas the inductance is the measurement part that varies due to eddy current interactions with the rod.
For the rod shape measurement of hot rolled round steel bars (rods) the high frequency eddy current method is especially well suited as it requires no contact point and is not limited to below the Curie temperature. Defects of the rod's shape can be detected by measuring the impedance spectrum of the RLC-oscillator. In the first laboratory setup an Agilent impedance analyser was used for initial tests. Nevertheless, this setup cannot be applied in a steel plant due to the difficult environmental conditions. Hence, a vector network analyser for passive impedance measurement that is applicable in these surroundings was developed.
Optimization of Encircling Eddy Current Sensors for Online Monitoring of Hot Rolled Round Steel Bars
(2014)
Modern manufacturing industries are continually working on quality enhancements for the hot rolling process of round products. One method for improving the finalisation of the rods is the implementation of an automatic size control system. As a result of these trends over the last few years, there has been an increasing demand for more accurate online measurements. Thus the reason for the research performed for this thesis. A particular challenge throughout this research was dealing with the temperature changes (up to 1200°C) from the in- and output of the fervent rolling stocks, and the effect this temperature changes had on the sensors. Furthermore, there is also high demand for developing fast and practical electronic measuring equipment, capable of measuring during high transport velocities (up to 120 m/s). The eddy current principle is just one of the very few methods available which can with-stand such harsh industrial environments. In fact, eddy current sensors are already being integrated into online monitoring tasks for hot rolling processes. The measurement uncertainty, however, is still considerably large for process control purposes. One reason for this lies within the ability for eddy current detectors to receive signals influenced by outward forces, i.e. forces dependent on its location, its geometry, the outside temperature and the material properties of a particular target. Thus the current accuracy for a cross-sectional area measurement, for example, is no higher than 1%. As a result, this thesis investigates the magnitude of all individual influential factors on the eddy current detectors, using model-based analysis techniques. The analytical model provides a solution for all rotationally symmetrical targets and the FEA model covers all of the other influencing parameters in a more time consuming manner. This thesis then provides different methods which are developed to separate the cross-sectional area measurement of a rod from all of the other influencing parameters. In addition, a material tracking approach for round products is developed. Two different kinds of prototypes, capable of measuring approximately 466 Tons of red-hot steel rods during the production process, are finally introduced in this thesis. The usefulness of the eddy current principle is validated by the provided field test results. The count accuracy for the identification of 2876 bars was found to be 99.93%, and the average measurement accuracy for the cross-sectional area experiments was reduced to ± 0.29 % when including all of the findings.
Coming out of the labs, the first robots are currently appearing on the consumer market. Initially they target rather simple application scenarios ranging from entertainment to home convenience. However, one can expect, that they will capture more complex areas soon. These robots will have a higher and higher level and a broad range of functional competence, and will collaborate and interactively communicate with their human users. All this requires considerable cognitive abilities on the robot’s side and appropriate man-machine interaction technologies. Apart from further development of individual functions and technologies it is crucial to build and evaluate fully integrated systems. This paper describes our approach to construct a robotic assistance system. We present experience with an integrated technology demonstration and the exposure of the integrated system to the public.
The first robots are currently appearing on the consumer market. Initially they are targeted at rather simple applications such as entertainment and home convenience. For more complex areas, these robots will need to collaborate and interactively communicate with their human users, which requires appropriate man-machine interaction technologies and considerable cognitive abilities on the robot's side. Consumer acceptance will strongly depend on the integrated system. Thus, system integration and evaluation of the integrated system is becoming increasingly important. This paper describes our approach to construct a robotic assistance system. We present experience with an integrated technology demonstration and exposure of the integrated system to the public.
Systems for automated image analysis are useful for a variety of tasks and their importance is still increasing due to technological advances and an increase of social acceptance. The main focus of "Technical Image Processing of Dynamic Scenes" lies
with the development of methods for the interpretation of images derived from various sensors. Apart from conventional visual images, this involves mainly X-ray and radar images. Taking into account the requirements of the various applications, suitable methods are derived. Current projects are dealing with the analysis of traffic scenes, detection of detonators when X-raying luggage and determination of type and expansion of oil pollution in maritime surveillance.
To reduce the number of traffic accidents and to increase the drivers comfort, the thought of designing driver assistance systems arose in the past years. Fully or partly autonomously guided vehicles, particularly for road traffic, pose high demands on the development of reliable algorithms. Principal problems are caused by having a moving observer in predominantly natural environments. At the Institut fur Neuroinformatik methods for analyzing driving relevant scenes by computer vision are developed in cooperation with several partners from the automobile industry. We present a solution for a driver assistance system. We concentrate on the aspects of video-based scene analysis and organization of behavior.
Autonomous driving is one of the future visions in which many vehicle manufacturers are working with high pressure.
Nowadays, it is already supported partially by high-class vehicles. A completely autonomous journey is indeed the goal, but in cars for
the public road traffic still not available. Automatic lane keeping assistants, speed regulators as well as shield and obstacle detections
are parts or precursors on the way to completely autonomous driving.
The American vehicle manufacturer Tesla is not only known for its electric drive, but also for the fact that high-pressure work is carried out on the autonomous drive. Tesla is thus the only vehicle manufacturer to use its users as so-called beta testers for its assistance systems. The progress and the function of the currently available Model S in the field of assistance systems and autonomic driving is documented and described in this paper. It is shown how good or bad the test vehicle manages scenarios in normal road traffic situations
with the assistance systems, e.g. lane keeping assistant, speed control, lane change and distance assistant, and which scenarios can
not be managed by the vehicle itself.
Relax yourself - Using Virtual Reality to enhance employees mental health and work performance
(2019)
This paper presents work-in-progress aiming to develop an actively adapting virtual reality (VR) relaxation application. Due to the immersive nature of VR technologies, people can escape from their real environment and get into a relaxing state. Goal of the application is to adapt to the users' physiological signals to foster the positive effect. Until now, a first version of the VR application was constructed and is currently evaluated in an experiment. Preliminary results of this study demonstrate that people appreciate the immersion into the virtual environment and escape from reality. Moreover, participants highlighted the option to adapt users' needs and preferences. Based on the final study data, the constructed application will be enhanced with regard to adoption and surrounding factors.
Why do barriers to the exchange of open knowledge resources change in public administrations? Experts in the public sector have been interviewed and outlined antecedents of change to certain barriers. The results are an initial step towards theorizing on barrier change and stepping beyond the current trend of categorizing difficulties to e-Learning and use of open knowledge resources. Categorizing only shows the range of potential challenges. Whether and how the barriers change, however, is seldom addressed in previous literature. The results presented in this study thus provide a new perspective on the phenomenon. Results are part of a longitudinal study about open e-Learning in the public sector across four European countries. They will provide fresh empirical input for discussions at the World Conference on E-Learning how to advance future research and practices in the domain
The goal of this paper is to define relevant barriers to the exchange of Open Educational Resources in local public administrations. Building upon a cultural model, eleven experts were interviewed and asked to evaluate several factors, such as openness in discourse, learning at the workplace, and superior support, among others. The result is a set of socio-cultural factors that shape the use of Open Educational Resources in public administrations. Significant factors are, in this respect, the independent choice of learning resources, the spirit of the platform, the range of available formats and access to technologies. Practitioners use these factors to elaborate on the readiness of public administrations towards the use of open e-Learning systems. To academic debates on culture in e-Learning, the results provide an alternative model that is contextualized to meet the demands of public sector contexts. Overall, the paper contributes to the lack of research about open e-Learning systems in the public sector, as well as regarding culture in the management of learning and knowledge exchange.
This article presents a omparative study of the barriers to open e-learning in public administrations in Luxembourg, Germany, Montenegro and Ireland. It discusses the current state of open e-learning of public administration employees at the local government level and derives the barriers to such learning. This paper's main contribution is its presentation of an empirical set of barriers in the four European countries. The results allow informed assumptions about which barriers will arise in the forthcoming use of open-source e-learning technology, particularly open educational resources as means of learning. Furthermore, this study offers a contextualised barrier framework that allows the systematic capture and comparison of challenges for future studies in the field. Other practical contributions include providing advice about open e-learning programmes, systematising lessons learned and addressing managerial implications.
E-Learning and openness in education are receiving ever increasing attention in businesses as well as in academia. However, these practices have only to small extent been introduced in public administrations. The study addresses this gap by presenting a literature review on Open Educational Resources [OER] and E-Learning in the public sector. The main goal of the article is to identify challenges to open E-Learning in public administrations. Experiences will be conceptualized as barriers which need to be considered when introducing open E-Learning systems and programs in administrations. The main outcome is a systematic review of lessons learned, presented as a contextualized Barrier Framework which is suitable to analyze requirements when introducing E-Learning and OER in public administrations.
The paper provides a contextualization process to adapt Open Knowledge Resources for the need of public administrations. By help of a matching strategy, culture and context profiles of learners and learning resources are compared. The comparison allows to draw inferences how to contextualize an open knowledge resource for own learning needs. An example is illustrated and future research fields are proposed.
This chapter describes our research efforts related to the design of mobile learning (m-learning) applications in cloud-computing (CC) environments. Many cloud-based services can be used/integrated in m-learning scenarios, hence, there is a rich source of applications that could easily be applied to design and deploy those within the context of cloud-based services. Here, we present two cloud-based approaches—a flexible framework for an easy generation and deployment of mobile learning applications for teachers, and a flexible contextualization service to support personalized learning environment for mobile learners. The framework provides a flexible approach that supports teachers in designing mobile applications and automatically deploys those in order to allow teachers to create their own m-learning activities supported by mobile devices. The contextualization service is proposed to improve the content delivery of learning objects (LOs). This service allows adapting the learning content and the mobile user interface (UI) to the current context of the user. Together, this leads to a powerful and flexible framework for the provisioning of potentially ad hoc mobile learning scenarios. We provide a description of the design and implementation of two proposed cloud-based approaches together with scenario examples. Furthermore, we discuss the benefits of using flexible and contextualized cloud applications in mobile learning scenarios. Hereby, we contribute to this growing field of research by exploring new ways for designing and using flexible and contextualized cloud-based applications that support m-learning.
This chapter describes our current research efforts related to the contextualization of learners in mobile learning activities. Substantial research in the field of mobile learning has explored aspects related to contextualized learning scenarios. However, new ways of interpretation and consideration of contextual information of mobile learners are necessary. This chapter provides an overview regarding the state of the art of innovative approaches for supporting contextualization in mobile learning. Additionally, we provide the description of the design and implementation of a flexible multi-dimensional vector space model to organize and process contextual data together with visualization tools for further analysis and interpretation. We also present a study with outcomes and insights on the usage of the contextualization support for mobile learners. To conlcude, we discuss the benefits of using contextualization models for learners in different use-cases. Moreover, a description is presented in order to illustrate how the proposed contextual model can easily be adapted and reused for different use-cases in mobile learning scenarios and potentially other mobile fields.
In this paper we present an approach for contextual big data analytics in social networks, particularly in Twitter. The combination of a Rich Context Model (RCM) with machine learning is used in order to improve the quality of the data mining techniques. We propose the algorithm and architecture of our approach for real-time contextual analysis of tweets. The proposed approach can be used to enrich and empower the predictive analytics or to provide relevant context-aware recommendations.
Mobile devices, in the form of smartphones, are endowed with rich capabilities in terms of multimedia, sensors and connectivity. The wide adoption of these devices allows using them across different settings and situations. One area in which mobile devices become more and more prominent is within the field of mobile learning. Here, mobile devices provide rich possibilities for the contextualization of the learner, by using the set of sensors available in the device. On the one hand, the usage of mobile devices enables participation in learning activities independent of time and space. Nevertheless, developing mobile learning applications for the heterogeneity of mobile devices available in the market becomes a challenge. Not only this is a problem related to form factor aspects, but also the large number of different operating systems, platforms and app infrastructures (app stores) are aspects to be considered. In this paper we present our initial efforts with regard to the development of cross-platform mobile applications to support the contextualization of learning content.
In this paper we present an approach for People-to-People recommendations based on a Rich Context Model (RCM). We consider personal user information as contextual information used for our recommendations. The evaluation of our recommendation approach was performed on a social network of students. The obtained results do show a significant increase in performance while, at the same time, a slight increase in quality in comparison to a manual matching process. The proposed approach is flexible enough to handle different data types of contextual information and easy adaptable to other recommendation domains.
Recommender systems have become an important application domain related to the development of personalized mobile services. Thus, various recommender mechanisms have been developed for filtering and delivering relevant information to mobile users. This paper presents a rich context model to provide the relevant content of news to the current context of mobile users. The proposed rich context model allows not only providing relevant news with respect to the user’s current context but, at the same time, also determines a convenient representation format of news suitable for mobile devices.
Fat content of liver is an essential parameter to decide whether a liver is suitable for transplantation or not. The determination of fat content is often challenging and usually there is not enough time to bring a specimen to a pathologic laboratory. That is why transplantation clinics need a technique to measure the fat content of a graft. In this paper the theoretical basics and an existing laboratory setup are presented.
The mathematical competence of first year students is an important success factor at least for technical studies. As a significant percentage of students do not have sufficient mathematical skills, universities often utilise blended learning courses to increase these skills prior to the start of studies. Due to the diversity of students and their educational backgrounds, individual strategies are needed to achieve the necessary competence for successfully managing their studies. This paper describes our approach at the University of Applied Sciences Ruhr West, where we are using personalized blended learning concepts based on the measurement of individual mathematical competences at the beginning of a coaching process. This is used to gain a better matching between the individual learner level and the adapted learning concepts. We combine individual presence learning groups and a personalized e-learning environment. This environment is adapted based on mathematical skills of each stud ent. It uses individual learning advices, short-term optical feedback and up to date e-learning material in a Moodle-based LMS (learning management system). The coaching concept is approved by the results of summative and formative evaluations.
Increasing economic viability and safety through structural health monitoring of wind turbines
(2017)
Serious accidents with property damage or even human casualties, result from structural flaws in wind turbine rotor blades. Common maintenance practices result in long downtimes and do not lead to the required results. Therefore, the Ruhr West University of Applied Sciences and the iQbis Consulting GmbH, currently research a new structural health monitoring method for wind turbine rotor blades. The goal of this project is to build a sensor system that can detect structural weaknesses inside of rotor blades without the need of downtime for industrial climbers. This technology has the potential to prevent accidents, save lives, extend the useful life of wind turbines and optimize the production of green energy.
We present a pipeline for recognizing dynamic freehand gestures on mobile devices based on extracting depth information coming from a single Time-of-Flight sensor. Hand gestures are recorded with a mobile 3D sensor, transformed frame by frame into an appropriate 3D descriptor and fed into a deep LSTM network for recognition purposes. LSTM being a recurrent neural model, it is uniquely suited for classifying explicitly time-dependent data such as hand gestures. For training and testing purposes, we create a small database of four hand gesture classes, each comprising 40 × 150 3D frames. We conduct experiments concerning execution speed on a mobile device, generalization capability as a function of network topology, and classification ability ‘ahead of time’, i.e., when the gesture is not yet completed. Recognition rates are high (>95%) and maintainable in real-time as a single classification step requires less than 1 ms computation time, introducing freehand gestures for mobile systems.
In this contribution we present a novel approach to transform data from time-of-flight (ToF) sensors to be interpretable by Convolutional Neural Networks (CNNs). As ToF data tends to be overly noisy depending on various factors such as illumination, reflection coefficient and distance, the need for a robust algorithmic approach becomes evident. By spanning a three-dimensional grid of fixed size around each point cloud we are able to transform three-dimensional input to become processable by CNNs. This simple and effective neighborhood-preserving methodology demonstrates that CNNs are indeed able to extract the relevant information and learn a set of filters, enabling them to differentiate a complex set of ten different gestures obtained from 20 different individuals and containing 600.000 samples overall. Our 20-fold cross-validation shows the generalization performance of the network, achieving an accuracy of up to 98.5% on validation sets comprising 20.000 data samples. The real-time applicability of our system is demonstrated via an interactive validation on an infotainment system running with up to 40fps on an iPad in the vehicle interior.
A simple copper coil without a voluminous stationary magnet can be utilized as a non-contacting transmitter and as a detector for ultrasonic vibrations in metals. Advantages of such compact EMATs without (electro-)magnet might be: applications in critical environments (hot, narrow, presence of iron filings…), potentially superior fields (then improved ultrasound transmission and more sensitive ultrasound detection).
The induction field of an EMAT strongly influences ultrasound transduction in the nearby metal. Herein, a simplified analytical method for field description at high liftoff is presented. Within certain limitations this method reasonably describes magnetic fields (and resulting eddy currents, inductances, Lorentz forces, acoustic pressures) of even complex coil arrangements. The methods can be adapted to conventional EMATS with a separate stationary magnet.
Increased distances (liftoff) are challenging and technically relevant, and this practical question is addressed: with limited electrical power and given free space between transducer and target metal, what would be the most efficient geometry of a circular coil? Furthermore, more complex coil geometries (“butterfly coil”) with a concentrated field and relatively higher reach are briefly investigated.
This experimental study demonstrates for the first time a solid-state circuitry and design for a simple compact copper coil (without an additional bulky permanent magnet or bulky electromagnet) as a contactless electromagnetic acoustic transducer (EMAT) for pulse echo operation at MHz frequencies. A pulsed ultrasound emission into a metallic test object is electromagnetically excited by
an intense MHz burst at up to 500 A through the 0.15 mm filaments of the transducer. Immediately thereafter, a smoother and quasi “DC-like” current of 100 A is applied for about 1 ms and allows an
echo detection. The ultrasonic pulse echo operation for a simple, compact, non-contacting copper coil is new. Application scenarios for compact transducer techniques include very narrow and
hostile environments, in which, e.g., quickly moving metal parts must be tested with only one, non-contacting ultrasound shot. The small transducer coil can be operated remotely with a cable
connection, separate from the much bulkier supply circuitry. Several options for more technical and fundamental progress are discussed.