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The cornerstone of cognitive systems is environment awareness which enables agile and adaptive use of channel resources. Whitespace prediction based on learning the statistics of the wireless traffic has proven to be a powerful tool to achieve such awareness. In this paper, we propose a novel Hidden Markov Model (HMM) based spectrum learning and prediction approach which accurately estimates the exact length of the whitespace in WiFi channels within the shared industrial scientific medical ISM) bands. We show that extending the number of hidden states and formulating the prediction problem as a maximum likelihood (ML) classification leads to a substantial increase in the prediction horizon compared to classical approaches that predict the immediate (short-term) future. We verify the proposed algorithm through simulations which utilize a model for WiFi traffic based on extensive measurement campaigns.
In der Diplomarbeit werden verschiedene, schon auf dem Markt befindliche Intrusion Intrusion Detection Systeme auf unterschiedliche Kriterien verglichen. Es werden mögliche Einsatzarten und Einsatzorte mit ihren Vor- und Nachteilen durchleuchtet und besprochen. Auf Basis der erlangten Erkenntnisse wird ein System vorgeschlagen, dass nach Abstimmung mit dem Projektleiter eingesetzt werden soll. Zu den Einsatz- kriterien gehören das vorhanden Budget, die Netzwerkumgebung, die Ausstattung und Leistungsfähigkeit des Einsatz-Intrusion Detection Systems sowie die Art des Intrusion Detection Systems. Geplant ist der Einsatz mindestens eines bzw. mehrerer Systeme als eine sogenannte Enterprise-Lösung. Mittels verschiedener Hilfsmittel und Tools werden die Intrusion Detection Systeme eTrust von Computer Associates, Real Secure von ISS, Snort, Tripwire und Network Intrusion Detection von Network Flight Recorder untersucht. Der Test und der Betrieb dieser Systeme geschieht sowohl vor als auch hinter der Firewall also in der demilitarisierten Zone des Unternehmens. Die Untersuchung der Systeme beinhaltet Kontrollen über Systemstabilität, Prozessor- und Hauptspeicherauslastung, Anzahl der erkannten Angriffe auf Basis simulierter Angriffe sowie die Benutzerfreundlichkeit
Die vorliegende Arbeit untersucht, wie Tools für die Überprüfung von Quell-Code auf Konformität mit Programmierstilen, die komplexere Entwurfsmuster beinhalten, als Erweiterung des statischen CodeAnalyse-Tools Checkstyle realisiert werden können. Als Beispiel wird der Joi Programmierstil verwendet, der für diese Arbeit aus der Java Spracherweiterung Joi (Java Objects by Interfaces), die die Einhaltung einiger Entwurfsmuster, die auf die Reduzierung von Code-Abhängigkeiten zielen, unterstützt, abgeleitet wurde.
Ballistocardiography (BCG) can be used to monitor heart rate activity. Besides, the accelerometer should have high sensitivity and minimal internal noise; a low-cost approach was taken into consideration. Several measurements have been executed to determine the optimal positioning of a sensor under the mattress to obtain a signal strong enough for further analysis. A prototype for an unobtrusive accelerometer-based measurement system has been developed and tested in a conventional bed without any specific extras. The influence of the human sleep position for the output accelerometer data was tested. The obtained results indicate the potential to capture BCG signals using accelerometers. The measurement system can detect heart rate in an unobtrusive form in the home environment.
Globalization has increased the number of road trips and vehicles. The result has been an intensification of traffic accidents, which are becoming one of the most important causes of death worldwide. Traffic accidents are often due to human error, the probability of which increases when the cognitive ability of the driver decreases. Cognitive capacity is closely related to the driver’s mental state, as well as other external factors such as the CO2 concentration inside the vehicle. The objective of this work is to analyze how these elements affect driving. We have conducted an experiment with 50 drivers who have driven for 25 min using a driving simulator. These drivers completed a survey at the start and end of the experiment to obtain information about their mental state. In addition, during the test, their stress level was monitored using biometric sensors and the state of the environment (temperature, humidity and CO2 level) was recorded. The results of the experiment show that the initial level of stress and tiredness of the driver can have a strong impact on stress, driving behavior and fatigue produced by the driving test. Other elements such as sadness and the conditions of the interior of the vehicle also cause impaired driving and affect compliance with traffic regulations.
Web services are, due to the excellent tool support, simple to provide and use in trivial cases. But their use in non-trivial Web service-based systems like I3M poses new difficulties and problems. I3M is an instant messaging and chat system with distributed and local components collaborating via Web services. One difficulty is to make a series of related Web service invocations in a stateful session. A problem is the performance of collaborating collocated, service-oriented components of a system due to the high Web service invocation overheaed as is shown by measurements. Solutions to both the difficulty and the problem are proposed.
Tauchsimulation
(2003)
Im 1.Kapitel werden die historischen Aspekte des Tauchens und der Tauchphysik beschrieben. Anhand von physikalischen Gesetzen, mathematischen Formeln und empirisch ermittelten Werten werden im 2. Kapitel die nötigen Grundlagen für das Verständnis zur Berechnung eines Tauchgangs vermittelt. Das 3.Kapitel behandelt verschiedene auf dem Markt befindliche Tauchsimulationen, zeigt deren Funktionsumfang sowie deren Vor- und Nachteile. Die erstellte Tauchsimulation wird im 4. Kapitel vorgestellt. Dabei wird auch auf verschiedene Simulationsläufe eingegangen. Zum Abschluß wird ein Ausblick auf aktuelle Entwicklungstendenzen gegeben.
Systematic Generation of XSS and SQLi Vulnerabilities in PHP as Test Cases for Static Code Analysis
(2022)
Synthetic static code analysis test suites are important to test the basic functionality of tools. We present a framework that uses different source code patterns to generate Cross Site Scripting and SQL injection test cases. A decision tree is used to determine if the test cases are vulnerable. The test cases are split into two test suites. The first test suite contains 258,432 test cases that have influence on the decision trees. The second test suite contains 20 vulnerable test cases with different data flow patterns. The test cases are scanned with two commercial static code analysis tools to show that they can be used to benchmark and identify problems of static code analysis tools. Expert interviews confirm that the decision tree is a solid way to determine the vulnerable test cases and that the test suites are relevant.