Accessibility evaluation of chats and forums in e-learning environments

Proceedings of: 2013 International Conference on Frontiers in Education: Computer Science & Computer Engineering (FECS'13): WORLDCOMP'13, July 22-25, 2013, Las Vegas, Nevada (USA)Collaborative learning is useful for students in their learning process. Nowadays, most e-learning systems include Computer Supported Collaborative Learning (CSCL) tools like chats and forums; however, are they accessible for everybody? This paper presents a heuristic evaluation of accessibility of two CSCL tools (chat and forum) in four web-based, open-source Learning Content Management Systems (LCMS): Moodle, ATutor, dotLRN and Claroline. The evaluation results show that the CSCL tools evaluated present accessibility barriers which are a handicap for many students who want to use the LCMSs Moreover, some recommendations are offered in order to improve the accessibility of the evaluated tools. Considering these recommendations in the development of the evaluated tools, all students could participate actively in the collaborative tasks proposed by teachersThis research work has been supported by the Regional Government of Madrid under the Research Network MA2VICMR (S2009/TIC-1542) and by the Spanish Ministry of Economy under the project MULTIMEDICA (TIN2010-20644-C03-01)Publicad

What Kills People in a Fire? Heat or Smoke?

This paper reviews the main causes of casualties in fires, investigates the composition of the smoke in typical compartment fire and assesses the contribution of each component to the overall potency of the smoke. The leading cause of death for fire victims around the world has been smoke inhalation for many decades. Also fires occurring in buildings are responsible for over 75% of total fire fatalities. Several major fire accidents, where fire toxicity was the cause of death for almost all victims, are highlighted. Statistical reviews of fire casualties for several decades in the UK and the USA show that fire toxicity is the major cause of death for fire victims. The analysis of the smoke species in a typical compartment fire with wood pallets as fuel, clearly demonstrates that acrolein is the major component of smoke responsible for incapacitation while CO is the main species responsible for the lethality

EIPECK: Assessing Educators’ Pedagogical Content Knowledge for Engineering Integration in K-12

Global efforts are underway to include engineering in pre-college curricula. In the USA, this pursuit led to the inclusion of engineering content in the most recent version of the Next Generation Science Standards that guide K-12 science. As these standards become part of the K-12 curriculum, teachers face the challenge of gaining basic engineering literacy, while developing the associated inclusive pedagogies necessary to integrate engineering content into their classrooms. In this context, teacher preparation programs can benefit from easy-to-implement tools that measure preservice teachers’ readiness to integrate engineering content in their future classrooms. This work describes the development and validation of an instrument to help assess educators’ perceived levels of pedagogical content knowledge for engineering integration at single or multiple time points throughout their academic preparation. The proposed instrument can complement other assessment methods, such as classroom observations, interviews, and journal entries. Additionally, the instrument can be used to help discern the effectiveness of teacher preparation programs in preparing future teachers to integrate engineering

A Cloud-based Intrusion Detection and Prevention System for Mobile Voting in South Africa

Publishe ThesisInformation and Communication Technology (ICT) has given rise to new technologies and solutions that were not possible a few years ago. One of these new technologies is electronic voting, also known as e-voting, which is the use of computerised equipment to cast a vote. One of the subsets of e-voting is mobile voting (m-voting). M-voting is the use of mobile phones to cast a vote outside the restricted electoral boundaries. Mobile phones are pervasive; they offer connection anywhere, at any time. However, utilising a fast-growing medium such as the mobile phone to cast a vote, poses various new security threats and challenges. Mobile phones utilise equivalent software design used by personal computers which makes them vulnerable or exposed to parallel security challenges like viruses, Trojans and worms. In the past, security solutions for mobile phones encountered several restrictions in practice. Several methods were used; however, these methods were developed to allow lightweight intrusion detection software to operate directly on the mobile phone. Nevertheless, such security solutions are bound to fail securing a device from intrusions as they are constrained by the restricted memory, storage, computational resources, and battery power of mobile phones. This study compared and evaluated two intrusion detection systems (IDSs), namely Snort and Suricata, in order to propose a cloud-based intrusion detection and prevention system (CIDPS) for m-voting in South Africa. It employed simulation as the primary research strategy to evaluate the IDSs. A quantitative research method was used to collect and analyse data. The researcher established that as much as Snort has been the preferred intrusion detection and prevention system (IDPS) in the past, Suricata presented more effective and accurate results close to what the researcher anticipated. The results also revealed that, though Suricata was proven effective enough to protect m-voting while saving the computational resources of mobile phones, more work needs to be done to alleviate the false-negative alerts caused by the anomaly detection method. This study adopted Suricata as a suitable cloud-based analysis engine to protect a mobile voting application like XaP

Nutzung kryptographischer Funktionen zur Verbesserung der Systemzuverlässigkeit

Cryptographic techniques deal with securing information against unwanted usage, while coding techniques deals with keeping data error-free and retrieving them reliably. However, both techniques share many tools, bounds and limitations. In this thesis, several novel approaches towards improving system reliability by combining cryptographic and coding techniques in several constellations are presented. The first constellation is deploying pure cryptographic functions to improve reliability issues overshadowed in systems that previously had no reliability-supporting coding mechanisms. Such systems could have just authenticity, secrecy and/or integrity mechanisms for security services. The second constellation deploys a mixture of both cryptographic functions and error correction codes to improve the overall system reliability. The first contribution in this thesis, presents a new practical approach for detection and correction of execution errors for AES cipher. The source of such errors could be natural or as a result of fault injection attacks. The proposed approach is making use of the two linear mappings in the AES round structure for error control. The second contribution is investigating the possibility and ability of deploying pure cryptographic hash functions to detect and correct a class of errors. The error correction is achieved by deploying a part of the hash bits to correct a class of selected unidirectional error class with high probability. The error correction process would degrade the authentication level in a non-significant fashion. In the third and fourth contributions, we propose algorithms to improve system correctability beyond classical limits by combining coding and cryptographic functions. The new algorithms are based mainly on the fundamentals investigated in the second contribution as mechanisms to detect and correct errors. The new algorithms are investigated in terms of collision and attacking complexity, as error correction via hash matching is similar to a successful authentication attack. The resulting performance showed achievable good error correctability, authenticity, and integrity figures.Kryptografische Methoden zielen der Sicherung von Information gegen unerwünschte Nutzung, wobei Codierungstechnik behandelt die Korrektur der Fehler in den Daten und deren zuverlässigen Rückgewinnung. Beide Techniken bedienen sich ähnlich Instrumente und besitzen ähnliche grenzen und Grenzwerte. In diese Dissertation, werden mehrere neue Verfahren zur Verbesserung der Systemzuverlässigkeit durch verschiedene Konstellationen zur Kombination der beiden Fehlerkontrollcodierung und Kryptografische Verfahren. In der ersten Konstellation werden reine kryptologische Funktionen verwendet, die zur Verbesserung der Zuverlässigkeitsaspekte in den Systemen die keine Zuverlässigkeitsfördernde Codierungs-Maßnahme enthalten dienen. Solche Systeme besitzen z. B. nur Authentifikation, Geheimhaltung oder Integritäts-Mechanismen in den Sicherheitsdiensten. Die zweite Konstellation verwendet eine Kombination von Fehlerkorrigierende Codes und Krypto-Mechanismen für die Verbesserung der Zuverlässigkeit des Systems. Der erste Beitrag in diese Arbeit präsentiert ein neues praktisches Verfahren zur Erkennung und Korrektur von Verarbeitungsfehler in AES Chiffre. Die Ursachen solche Fehler konnten natürlich oder als Resultat eines beabsichtigten „Fault Injection“ Angriff sein. Das Verfahren nutzt die linearen Abbildungen im AES Runden-Funktion für Fehlerkontrolle. Der zweite Beitrag untersucht die Möglichkeit und Fähigkeit zur Einsatz von Hashfunktionen zur Erkennung und Korrektur vom Fehler. Die Fehlerkorrektur ist erreicht durch die Nutzung eines Anteil des Hash Bits um eine Klasse von ausgewähltem Unidirektionalen-Fehler mit höhe Wahrscheinlichkeit zu korrigieren. Dabei wird der Fehlerkorrekturprozess die Authentifikationsgrad des Hashfunktion nicht signifikant reduzieren. In den dritten und vierten Beitrag werden Algorithmen vorgeschlagen um die Zuverlässigkeit des System über die klassischen grenzen verbessert. Das wird durch Kombination von Kryptologischen und Codierung Funktionen erreicht. Die neuen Algorithmen sind auf die fundamentale Untersuchungen des zweiten Beitrag als Mechanismen für Fehlererkennung und Fehlerkorrektur basiert. Die neuen Algorithmen sind auf deren Kollision und Angriffskomplexität Verhalten untersucht worden, da Fehlerkorrektur durch Hashwert-Anpassung eines erfolgreichen Authentifikationsangriff ähnlich ist. Die resultierenden Verhalten zeigen gute Werte für erreichbare Fehlerkorrekturfähigkeit, Authentifikations-Grad und Integrität

A comparative study of in-band and out-of-band VOIP protocols in layer 3 and layer 2.5 environments

For more than a century the classic circuit-switched telephony in the form of PSTN (Public Service Telephone Network) has dominated the world of phone communications (Varshney et al., 2002). The alternative solution of VoIP (Voice over Internet Protocol) or Internet telephony has increased dramatically its share over the years though. Originally started among computer enthusiasts, nowadays it has become a huge research area in both the academic community as well as the industry (Karapantazis and Pavlidou, 2009). Therefore, many VoIP technologies have emerged in order to offer telephony services. However, the performance of these VoIP technologies is a key issue for the sound quality that the end-users receive. When making reference to sound quality PSTN still stands as the benchmark.Against this background, the aim of this project is to evaluate different VoIP signalling protocols in terms of their key performance metrics and the impact of security and packet transport mechanisms on them. In order to reach this aim in-band and out-of-band VoIP signalling protocols are reviewed along with the existing security techniques which protect phone calls and network protocols that relay voice over packet-switched systems. In addition, the various methods and tools that are used in order to carry out performance measurements are examined together with the open source Asterisk VoIP platform. The findings of the literature review are then used in order to design and implement a novel experimental framework which is employed for the evaluation of the in-band and out-of-band VoIP signalling protocols in respect to their key performance networks. The major issue of this framework though is the lack of fine-grained clock synchronisation which is required in order to achieve ultra precise measurements. However, valid results are still extracted. These results show that in-band signalling protocols are highly optimised for VoIP telephony and outperform out-of-band signalling protocols in certain key areas. Furthermore, the use of VoIP specific security mechanisms introduces just a minor overhead whereas the use of Layer 2.5 protocols against the Layer 3 routing protocols does not improve the performance of the VoIP signalling protocols

A NEW ENERGY EFFICIENT ADAPTIVE HYBRID ERROR CORRECTION TECHNIQUE FOR UNDERWATER WIRELESS SENSORS NETWORKS

Underwater wireless sensors networks find many applications in today's life. However underwater sensors are still relatively expensive. They suffer from short lifetime which is limited by batteries lifetime as it is difficult to recharge or even replace batteries in harsh aquatic medium. When the battery is depleted the sensor is of no use anymore. So designing energy efficient communication protocols is an important issue for underwater sensors networks. Underwater is characterized by variable channel conditions, whereas underwater sensors are mobile due to water currents leading to variable distances between sensors. This variability in channel conditions and distances between sensors leads to inefficiency in energy consumptions when using fixed type of error correction technique. In this thesis, a mathematical energy efficiency derivations for the two main error correction techniques (Automatic Repeat request (ARQ) and Forward Error Correction (FEC)) in underwater environment has been done. The results from those derivations show that one technique is more energy efficient than the other below specific distance, where as the other is more energy efficient after this distance. This specific distance is found to be unfixed and varies with the variation in channel conditions and packet size. So using fixed error correction technique for specific distance is not accurate. Simulation has been done which validate the mathematical derivations. Based on the above derivation results Adaptive Hybrid Error Correction (AHEC) technique which adaptively changes the error correction technique to the technique that gives the highest energy efficiency for the current channel conditions and distances has been proposed. The technique uses an adaptation algorithm which depends on a pre-calculated packet acceptance rate (PAR) ranges look-up table, current PAR, packet length and current error correction technique used. AHEC viii technique has been found to have better energy saving compared with the techniques that depend on pure ARQ or FEC only. This saving ranges from 10 to 70 % in energy saving in ARQ case , and 7 to 10 % in energy saving in FEC case depending on current channel conditions and distance .It has also been compared with the technique that uses variable power supply in adaptation (Adaptive Variable Power Supply (AVPS)) and it achieves between 20 to 60 % in energy saving depending on current channel conditions and distance. It has also been compared with Adaptive Redundancy Reliable Transport Protocol (ARRTP), and it achieves between 10 to 80 % in energy saving depending on the current channel conditions and distance. The adaptation algorithm which depends on PAR has also been applied in adaptation to the ARRTP which originally depends only on inter-node distance in adaptation. PAR take both of distance and channel conditions into consideration. This technique is called PAR-based ARRTP, and the results shows better adaptation than the basic ARRTP in variable channel conditions cases. AHEC technique has also been applied with the bounded distance routing protocol to minimize the effects of variable channel conditions. Bounded distance routing protocol design depends on choosing specific number of relays between sender and receiver that minimize the total energy consumptions. This specific number of relays varies with the variation in channel conditions. The results show a deviation in number of relays from 6 when fixed error correction technique is used to only 2 when AHEC technique is used with it