Steinau an der Strasse, Germany

UniveWismar University of Applied Sciences
Steinau an der Strasse, Germany
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Ahrens A.,UniveWismar University of Applied Sciences | Lochmann S.,UniveWismar University of Applied Sciences
Proceedings - 2016 Advances in Wireless and Optical Communications, RTUWO 2016 | Year: 2016

Polynomial matrix singular value decomposition (PMSVD) plays a very important role in broadband multiple-input multiple-output (MIMO) systems. It can be used to decompose a broadband MIMO channel matrix in order to recover the transmitted signals corrupted by the channel interference (CI) at the receiver. In this contribution singular value decomposition (SVD) algorithm for polynomial matrices are analyzed and compared in the application of decomposing optical MIMO channels. The bit-error rate (BER) performance is evaluated and optimized by applying bit and power allocation schemes. For our simulations, the specific impulse responses of a (2 × 2) MIMO channel, including a 1.4 km multi-mode fiber and optical couplers at both ends, are measured for the operating wavelength of 1576 nm. © 2016 IEEE.

Agency: European Commission | Branch: FP7 | Program: CP-FP | Phase: SST.2012.4.1-1. | Award Amount: 3.83M | Year: 2012

Up to 96% of maritime accidents (collision, grounding, fire, occupational accidents) are routinely attributed to human error. However, rather than assessing the ship performance in terms of global design factors such as ship motions and noise, the human element studies have primarily focused on local design features (e.g., bridge design) that are relatively easy to fix and tune towards required effects on the crew. From the formal point of view, the key element that has been missing and therefore preventing the integration of the human element into ship design projects is a comprehensive quantification of crew performance failure. Given the natural uncertainty of the maritime environment, such quantification must be probabilistic and therefore commensurate with safety-driven ship design methods such as the Risk-Based Design. In project FAROS, the rationalised nature of the Risk-Based Design will be used to integrate the human element into the ship safety framework and deliver ship concepts (ro-pax and tanker) that are safe, economic and green. This will be achieved by (1) quantitatively linking global design factors to the crew performance failure modes (fatigue, gross and fine motor skills etc.) and (2) optimising multi-disciplinary ship performance using state-of-the-art tools, methods and empirical knowledge. It is expected that the societal and personal risks on tanker and ro-pax ships can be reduced at least by 30%, provided recommended amendments to design rules are implemented and the developed ship design assessment framework, which takes into account the crew performance at sea, is used in daily ship design practice by parties relevant.

Agency: European Commission | Branch: FP7 | Program: CP-FP | Phase: SST.2012.5.2-5. | Award Amount: 3.83M | Year: 2012

MUNIN aims to develop an autonomous ship concept, which is described according to the Waterborne TP Agenda by combination of automated decision systems with remote control via a shore based station. The vision of MUNIN is to show the update possibilities of todays fleet to autonomous vessel. The trend in maritime transport towards slow steaming increase the necessary total number of ships, while at the same time the lack of seafarers becomes urgent more and more. Human resources are seen as one of the critical enablers for maritime growth within the EU. MUNINs concept allows handling this challenge due to more efficient and competitive ship operation. Additionally, Tthe shore based approach offers seafaring furthermore the possibility to become further socially sustainable. MUNINs results will also provide efficiency, safety and sustainability advantages for existing vessels in short term, without necessitating the use of autonomous ships. This includes e.g. environmental optimization, new maintenance and operational concepts as well as improved bridge applications. Furthermore autonomous ship-models could be an improvement for education purpose in ship simulators. For an autonomous ship several tasks which are currently done on board have to be redesigned. These are e.g. navigation, manoeuvring, watch keeping, maintenance, repair and engine optimization. Based on as-is-analyses MUNIN will define necessary change demands for manned vessels and develop concepts and applications to enable and optimize navigation and operation of an autonomous ship, which includes an evaluation of the communication architecture. Technical as well as organizational and legal aspects of unmanned shipping will be taken into account. Feasibility of the proposed concepts will be verified by an integrated simulator setup. Furthermore an assessment in terms of cost-benefit as well as safety and liability aspects will be done. MUNIN will embed itself in IMOs eNavigation- and EUs eMaritime-Initiative.

Ahrens A.,UniveWismar University of Applied Sciences | Benavente-Peces C.,Technical University of Madrid
WINSYS 2010 - Proceedings of the International Conference on Wireless Information Networks and Systems | Year: 2010

In this contribution we jointly optimize the number of multiple-input multiple-output (MIMO) layers and the number of bits per symbol within an iteratively-detected multiuser MIMO downlink (DL) transmission scheme under the constraint of a given fixed data throughput and integrity. Instead of treating all the users jointly as in zero-forcing (ZF) multiuser transmission techniques, the investigated singular value decomposition (SVD) assisted DL multiuser MIMO system takes the individual user's channel characteristics into account. In analogy to bit-interleaved coded irregular modulation, we introduce a MIMO-BICM scheme, where different user-specific signal constellations and mapping arrangement were used within a single codeword. Extrinsic information transfer (EXIT) charts are used for analyzing and optimizing the convergence behaviour of the iterative demapping and decoding. Our results show that in order to achieve the best bit-error rate, not necessarily all user-specific MIMO layers have to be activated.

Moller S.,University of Limerick | Newe T.,University of Limerick | Lochmann S.,UniveWismar University of Applied Sciences
Sensors and Actuators, A: Physical | Year: 2012

Many medical applications set new demands on sensor network designs. They often involve highly variable data rates, multiple receivers and security. Most existing sensor network designs do not adequately support these requirements, focusing instead on aggregating small amounts of data from nodes without security. In this paper, we present a software design for medical sensor networks. This framework provides a set of protocols and services specifically tailored for this application domain. It includes a secure communications model, an interface for periodic collection of sensor data, a dynamic sensor discovery protocol and protocols that monitor and save up to 70% of the energy of a node. The framework is built in TinyOS and a JAVA based user interface is provided to debug the framework and display the measured data. An extensive evaluation of the framework of a 6-node sensor test-bed is presented, measuring scalability and robustness as the number of sensors and the per node data rate are varied. The results show that the proposed framework is a scalable, robust, reliable and secure solution for medical applications. © 2011 Elsevier B.V. All rights reserved.

Ahrens A.,UniveWismar University of Applied Sciences | Lochmann S.,UniveWismar University of Applied Sciences
ICETE 2013 - 10th Int. Joint Conf. on E-Business and Telecommunications; 4th Int. Conf. DCNET 2013, - 10th Int. Conf. on ICE-B 2013 and OPTICS 2013 - 4th Int. Conf. on Optical Communication Systems | Year: 2013

The concept of MIMO (multiple input multiple output) transmission over multimode fibers has attracted increasing interest within the last years. Theoretically, the performance of the opticalMIMO multimode channel is well predictable. However, the realization of the opticalMIMO channel requires substantial further research. In this work the efficiency of optical couplers in MIMO systems is studied in a 1,4 km multimode testbed. Optical couplers have long been used as passive optical components able to combine or split SISO (singleinput single-output) data transmission from optical fibers. Our results show by the obtained measured impulse responses together with the simulated BER performance that optical couplers are well suited for the optical MIMO transmission despite their insertion losses and asymmetries. Comparing the different couplers those which maintain the different optical mode groups support the MIMO transmission more efficiently. Copyright © 2013 SCITEPRESS.

Mallwitz K.,UniveWismar University of Applied Sciences
World Transactions on Engineering and Technology Education | Year: 2013

This article presents developments and concepts in dual study courses in civil engineering education and the first findings and conclusions. Presented is an overview of dual study courses in Germany with special emphasis on civil engineering. Dual study courses in the German higher education context are illustrated, classified and explained. All in all, alumni of dual study courses stand a chance, whereas the chances of success for universities of applied sciences appear to be less in order to provide a homogeneous basis for advanced studies. In order to maintain the education at the highest level, quality assurance for both universities of applied sciences and universities is proposed. © 2013 WIETE.

Current Speech Dialogue Systems do not seem to have a good reputation. But what are the reasons?Which characteristics make dialogue systems more natural? Important features include adaptivity, mixed initiative, means for correction and over-answering, robust speech recognition, interpretation of colloquial language, negations and references as well as a basic social behaviour. When comparing current systems, we discover that many of these features have not been implemented yet. One main reason is the missing of a comprehensive dialogue modelling and implementation tool. At the same time, there may exist a certain discrepancy between industry and science.While industry claims that it does not need more natural systems, scientists focus on isolated problems in a very detailed way that is often not directly adaptable for industrial usage. Our aim should be the joint development of an overall model in the context of applied sciences. © Springer-Verlag 2012.

Wego A.,UniveWismar University of Applied Sciences
Optik | Year: 2013

In this paper, the achievable accuracy of a reflectance spectrophotometer based on 18 LEDs of different peak wavelengths in the range of 390-710 nm for object illumination is reported. For simulating the accuracy, reflectance spectra of the color target ColorChecker® have been used. By weighting the reflectance spectra of the target with measured relative power distribution spectra of the employed LEDs, simulated spectral reflectance values of the target are obtained. For calculating color values, unique wavelength values must be assigned to the simulated spectral sample values. LEDs can be characterized by several wavelength parameters. It has been shown that, without applying a correction procedure, assigning the centroid-wavelength of the LEDs as color calculation basis delivers the best results. But if a linear correction matrix is introduced, an optimized equidistant wavelength assignment delivers the best results. The mean achievable precision is sufficient to determine color values below ΔEab < 0.3. © 2012 Elsevier GmbH.

Nowadays, due to advances in electrical devices, new digital media, lighting, information and communication technologies, cities are being used 24/7. The paper discusses critical aspects of Media Architecture in the context of public spaces as well as urban nighttime environments from the perspective of a practising lighting architect. The author examines recent issues of negative design approaches and presents proposals for improving future projects in the form of guiding principles. Additionally, to better illustrate the phenomenon, an attempt has been made to standardize terminology and to clarify the topic of Media Architecture in the context of artificial light used in the urban environment based on the author's practical and theoretical research work in the field.

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