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News Article | November 26, 2015

The sensor consists of four areas with different metal oxides. They change their temperature-dependent electric resistance when coming into contact with gases. Credit: KIT/HsKA Fires are frequently caused by smoldering cables. Novel sensors now help detect such smoldering fires at an early stage by analyzing the plastic vapors released by overheated insulating cables. Scientists of KIT and Karlsruhe University of Applied Sciences have developed these hybrid sensors that combine measurement processes with data evaluation. Their work is reported in the current issue of the Sensors & Transducers Journal. A smoldering cable can be detected with a little luck before it starts burning: The plastic coating changes color, there is a smell of burning. Hybrid sensors might detect the risk of cable fires earlier, even before they are perceived by eyes and nose. They detect the gases released from the plastic coating due to heating and reliably identify and analyze the gas mixture and its concentration. In addition, they can also detect interfering gases, such as propene or carbon monoxide, and, hence, exclude false alarms. To this end, the hybrid sensors do not only possess a gas-detecting sensor chip, but also the computation capacity and algorithms needed for evaluating measured data. "The combination of a smart evaluation process with physical measurement is the basic idea of this development," Dr. Hubert Keller, Simulation and Measurement Project Head of KIT's Institute for Applied Computer Science, explains. The highly sensitive and very reliable hybrid sensors might increase safety in cable ducts. In addition, their capability of finding gas mixtures and determining individual gas concentrations might be useful for detecting toxic mold gases during food control, explosive gases in fertilizer silos, or leaks of natural gas pipelines. "Hybrid sensors can be used anywhere as separate systems or in a network. They may also be combined with classical safety technology, such as infrared cameras," Keller says. "For the development of the sensor, we use the effect that various gases react in different ways with gas-sensitive metal oxides as a function of temperature," Professor Dr. Heinz Kohler of the Institute of Sensor Technology and Information Systems (ISIS) of the Karlsruhe University of Applied Sciences says. "This effect is the basis of a self-heated, temperature-controlled sensor chip with four sensors, i.e. a sensor array. "The sensor array is heated cyclically and cooled down again. Simultaneous measurement of electric resistance or conductance yields four specific conductance signatures, the evaluation of which provides information on the composition and concentration of the gas. The current issue of the Sensors & Transducers Journal reports this development in the area of hybrid sensor technology. Combination of sensor technology and analysis method was funded with EUR 1.3 million for a duration of three years under the hybrid sensor platform project. The project team consisted of computer scientists and mathematicians of KIT, Karlsruhe University of Applied Sciences, and two industry partners. The process has already attracted worldwide attention and won a best paper award for excellent research contributions at two international conferences. Explore further: Butterfly wings help break the status quo in gas sensing More information: Rolf Seifert, Hubert B. Keller, Navas Illyaskutty, Jens Knoblauch, Heinz Kohler: Numerical Signal Analysis of Thermo-Cyclically Operated MOG Gas Sensor Arrays for Early Identification of Emissions from Overloaded Electric Cables. Sensors & Transducers Journal, Vol. 193, Issue 10, October 2015. 

Matthes J.,Institute for Applied Computer Science | Hock J.,Institute for Applied Computer Science | Waibel P.,Institute for Applied Computer Science | Scherrmann A.,Karlsruhe Institute of Technology | And 2 more authors.
Experimental Thermal and Fluid Science | Year: 2015

A high-speed camera based approach for the analysis of the trajectories, the velocities and the burning behavior of alternative fuel macroscopic particles during co-firing in a coal dust flame is presented. The new approach can be used as on-line measurement for the burner control. It consists of an image processing and a particle tracking step. The image processing algorithm allows for the detection of particles within as well as outside of the coal dust flame. The tracking algorithm connects particle detections in single images to particle trajectories in image sequences. It is tolerant to temporarily missing particle detections. Based on the particle trajectories various characteristic parameters describing the distribution of light duration and of the particle velocity can be calculated on-line. The new approach is demonstrated on the basis of measurements from an experimental combustion chamber with a 1. MW multi-fuel burner. © 2015 Elsevier Inc.

Wessel N.,Humboldt University of Berlin | Suhrbier A.,Institute for Applied Computer Science | Riedl M.,Humboldt University of Berlin | Marwan N.,Potsdam Institute for Climate Impact Research | And 3 more authors.
Proceedings of the Annual International Conference of the IEEE Engineering in Medicine and Biology Society, EMBS | Year: 2011

Directional coupling analysis of time series is an important subject of current research. In this paper, a method based on symbolic dynamics for the detection of time-delayed coupling in biosignals is presented. The symbolic coupling traces, defined as the symmetric and diametric traces of the bivariate word distribution, allow for a more reliable quantification of coupling and are compared with established methods like mutual information and cross recurrence analysis. The symbolic coupling traces method is applied to appropriate model systems and cardiological data which demonstrate its advantages especially for nonstationary and noisy data. Moreover, the method of symbolic coupling traces is used to analyze and quantify time-delayed coupling of cardiovascular measurements during different sleep stages. Significant different regulatory mechanisms are detected not only between the deep sleep and the other sleep stages but also between healthy subjects and patients. The proposed method may help to indicate pathological changes in cardiovascular regulation and also effects of continuous positive airway pressure therapy on the cardiovascular system. © 2011 IEEE.

Atli A.,Institute for Applied Computer Science | Atli A.,Karlsruhe Institute of Technology | Nau K.,Institute for Applied Computer Science | Nau K.,Karlsruhe Institute of Technology | Schmidt A.,Karlsruhe University of Applied Sciences
WEBIST 2011 - Proceedings of the 7th International Conference on Web Information Systems and Technologies | Year: 2011

In this paper, we will present an approach to visualizing arbitrary relational database contents in the form of object graphs via the World Wide Web. The focus is on the relationships between the datasets rather than on the data itself. The tool allows definition of different node types representing the datasets and edges representing the foreign keys and relationship tables in the database schema. Each node type has a label, and optionally a short description and a user definable image associated with it. The information for these fields can be extracted 1: 1 from the corresponding database tables or otherwise be aggregated from different tables. Along the edges, it is possible to navigate through the content of the database. At any time, exactly one node represents the center of the object graph. Starting from this graph, edges and other nodes down to a user-definable depth n are visualized. The depth n may vary along different node and edge types, so that it is possible to customize the representation of the object graph. The graphical representation of arbitrary database contents has been of great help to us. In addition to using it in the initial application area, we intend to use it in some other areas we had left unconsidered. From these, we can infer a number of suggestions as to how to improve our tool and make it more universal.

Penzel T.,Charite University Hospital | Suhrbier A.,Institute for Applied Computer Science | Bretthauer G.,Humboldt University of Berlin | Riedl M.,TU Dresden | And 4 more authors.
Proceedings of the Annual International Conference of the IEEE Engineering in Medicine and Biology Society, EMBS | Year: 2011

Sleep is a physiological process with an internal program of a number of well defined sleep stages and intermediate wakefulness periods. The sleep stages do modulate the autonomous nervous system and thereby the sleep stages are accompanied by different regulation regimes for the cardiovascular and respiratory system. The differences in regulation can be distinguished by new analysis techniques on the recorded signals. In addition to normal sleep regulation some sleep disorders affect the cardiovascular and respiratory regulation. The most prevalent disorder linked to sleep and changes in the autonomous system is obstructive sleep apnea. In patients with obstructive sleep apnea marked short term changes in cardiovascular and respiratory regulation are observed during sleep. These abnormalities in regulation are further differentiated between the sleep stages. For long term changes obstructive sleep apnea is recognized as a major risk factor for arterial hypertension. Treatment of obstructive sleep apnea lowers blood pressure during the night and over time also lowers blood pressure during daytime. In this study we investigated 18 patients with sleep apnea and normal blood pressure, 10 patients with sleep apnea and arterial hypertension and 10 normal subjects as controls. Both patient groups were tested with cardiorespiratory polysomnography before and under CPAP therapy. The effects on cardiovascular and respiratory regulation during sleep and daytime are investigated in the three groups. © 2011 IEEE.

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