University of Piraeus

About: University of Piraeus is a education organization based out in Piraeus, Attiki, Greece. It is known for research contribution in the topics: Context (language use) & Computer science. The organization has 1731 authors who have published 6209 publications receiving 106699 citations.

HERMES: aggregative LBS via a trajectory DB engine

Abstract: We present HERMES, a prototype system based on a powerful query language for trajectory databases, which enables the support of aggregative Location-Based Services (LBS). The key observation that motivates HERMES is that the more the knowledge in hand about the trajectory of a mobile user, the better the exploitation of the advances in spatio-temporal query processing for providing intelligent LBS. HERMES is fully incorporated into a state-of-the-art Object-Relational DBMS, and its demonstration illustrates its flexibility and usefulness for delivering custom-defined LBS.

A framework for the assessment of an organisation's innovation excellence

Abstract: Most firms competing in the global economy are paying increasing attention to innovation as the key driver of competitiveness. Innovation's key dimensions address the quality, the quantity and the speed of introducing innovations. With an increasing rate of change in the global economy, especially after the onset of the 2008–2009 economic crisis, innovation management emerges as a powerful way to facilitate a firm's adaptation to new conditions. However, despite a widespread acceptance of innovation's importance by the leadership of most companies, there is a general dissatisfaction with the results realised from innovation investments. For any organisation to address effectively the innovation challenge, its leadership must properly define the innovation system and process and apply sound quality and innovation management principles, as was done in the development of quality management and finance management. This requires the periodic assessment not only of innovation outputs, i.e. new products, service...

Fuzzy Logic for Adaptive Instruction in an E-learning Environment for Computer Programming

Abstract: In this paper, a novel approach to web-based education that performs individualized instruction on the domain of programming languages is presented. This approach is fully implemented and evaluated in an educational application module, called fuzzy knowledge state definer (FuzKSD). In particular, FuzKSD performs user modeling by dynamically identifying and updating a student's knowledge level of all the concepts of the domain knowledge. The operation of FuzKSD is based on fuzzy cognitive maps (FCMs) that are used to represent the dependences among the domain concepts. FuzKSD uses fuzzy sets to represent a student's knowledge level as a subset of the domain knowledge. Thus, it combines fuzzy theory with the overlay model. Moreover, it employs a novel inference mechanism that dynamically updates user stereotypes using fuzzy sets. It should be noted that the overlay model and stereotypes constitute two widely used methods for user modeling. However, they have not been combined with fuzzy sets thus far in the literature. The gain from this novel combination is significant as a student level of knowledge is represented in a more realistic way by automatically modeling the learning or forgetting process of a student with respect to the FCMs and thus the system can provide individualized adaptive advice. The application of this approach is not limited to adaptive instruction. It can also be used in other systems with changeable user states, such as e-shops, where consumers' preferences change over time and affect one another. Therefore, the particular module constitutes a novel generic fuzzy tool, which offers dynamic adaptation to users' needs and preferences of adaptive systems.

Network Security: Current Status and Future Directions

Abstract: Preface. Contributors. 1. Computer Network Security: Basic Background and Current Issues (Panayiotis Kotzanikolaou and Christos Douligeris). 1.1 Some Terminology on Network Security. 1.2 ISO/OSI Reference Model for Networks. 1.3 Network Security Attacks. 1.4 Mechanisms and Controls for Network Security: Book Overview and Structure. References. Part One Internet Security. 2. Secure Routing (Ioannis Avramopoulos, Hisashi Kobayashi, Arvind Krishnamurthy, and Randy Wang). 2.1 Introduction. 2.2 Networking Technologies. 2.3 Attacks in Networks. 2.4 State of the Art. 2.5 Conclusion and Research Issues. References. 3. Designing Firewalls: A Survey (Angelos D. Keromytis and Vassilis Prevelakis). 3.1 Introduction. 3.2 Firewall Classifi cation. 3.3 Firewall Deployment: Management. 3.4 Conclusions. References. 4. Security in Virtual Private Networks (Srinivas Sampalli). 4.1 Introduction. 4.2 VPN Overview. 4.3 VPN Benefi ts. 4.4 VPN Terminology. 4.5 VPN Taxonomy. 4.6 IPSec. 4.7 Current Research on VPNs. 4.8 Conclusions. References. 5. IP Security (IPSec) (Anirban Chakrabarti and Manimaran Govindarasu). 5.1 Introduction. 5.2 IPSec Architecture and Components. 5.3 Benefi ts and Applications of IPSec. 5.4 Conclusions. References. 6. IDS for Networks (John C. McEachen and John M. Zachary). 6.1 Introduction. 6.2 Background. 6.3 Modern NIDSs. 6.4 Research and Trends. 6.5 Conclusions. References. 7. Intrusion Detection Versus Intrusion Protection (Luis Sousa Cardoso). 7.1 Introduction. 7.2 Detection Versus Prevention. 7.3 Intrusion Prevention Systems: The Next Step in Evolution of IDS. 7.4 Architecture Matters. 7.5 IPS Deployment. 7.6 IPS Advantages. 7.7 IPS Requirements: What to Look For. 7.8 Conclusions. References. 8. Denial-of-Service Attacks (Aikaterini Mitrokotsa and Christos Douligeris). 8.1 Introduction. 8.2 DoS Attacks. 8.3 DDoS Attacks. 8.4 DDoS Defense Mechanisms. 8.5 Conclusions. References. 9. Secure Architectures with Active Networks (Srinivas Sampalli, Yaser Haggag, and Christian Labonte). 9.1 Introduction. 9.2 Active Networks. 9.3 SAVE Test bed. 9.4 Adaptive VPN Architecture with Active Networks. 9.5 (SAM) Architecture. 9.6 Conclusions. References. Part Two Secure Services. 10. Security in E-Services and Applications (Manish Mehta, Sachin Singh, and Yugyung Lee). 10.1 Introduction. 10.2 What Is an E-Service? 10.3 Security Requirements for EServices and Applications. 10.4 Security for Future EServices. References. 11. Security in Web Services (Christos Douligeris and George P. Ninios). 11.1 Introduction. 11.2 Web Services Technologies and Standards. 11.3 Web Services Security Standard. 11.4 Conclusions. References. 12. Secure Multicasting (Constantinos Boukouvalas and Anthony G. Petropoulos). 12.1 Introduction 205 12.2 IP Multicast. 12.3 Application Security Requirements. 12.4 Multicast Security Issues. 12.5 Data Authentication. 12.6 Source Authentication Schemes. 12.7 Group Key Management. 12.8 Group Management and Secure Multicast Routing. 12.9 Secure IP Multicast Architectures. 12.10 Secure IP Multicast Standardization Efforts. 12.11 Conclusions. References. 13. Voice Over IP Security (Son Vuong and Kapil Kumar Singh). 13.1 Introduction. 13.2 Security Issues in VoIP. 13.3 Vulnerability Testing. 13.4 Intrusion Detection Systems. 13.5 Conclusions. References. 14. Grid Security (Kyriakos Stefanidis, Artemios G. Voyiatzis, and Dimitrios N. Serpanos). 14.1 Introduction. 14.2 Security Challenges for Grids. 14.3 Grid Security Infrastructure. 14.4 Grid Computing Environments. 14.5 Grid Network Security. 14.6 Conclusions and Future Directions. References. 15. Mobile Agent Security (Panayiotis Kotzanikolaou, Christos Douligeris, Rosa Mavropodi, and Vassilios Chrissikopoulos). 15.1 Introduction. 15.2 Taxonomy of Solutions. 15.3 Security Mechanisms for Mobile Agent Systems. References Part Three Mobile and Security. 16. Mobile Terminal Security (Olivier Benoit, Nora Dabbous, Laurent Gauteron, Pierre Girard, Helena Handschuh, David Naccache, Stephane Socie, and Claire Whelan). 16.1 Introduction. 16.2 WLAN and WPAN Security. 16.3 GSM and 3GPP Security. 16.4 Mobile Platform Layer Security. 16.5 Hardware Attacks on Mobile Equipment. 16.6 Conclusion. References. 17. IEEE 802.11 Security (Daniel L. Lough, David J. Robinson, and Ian G. Schneller). 17.1 Introduction. 17.2 Introduction to IEEE 802.11. 17.3 Wired Equivalent Privacy. 17.4 Additional IEEE 802.11 Security Techniques. 17.5 Wireless Intrusion Detection Systems. 17.6 Practical IEEE 802.11 Security Measures. 17.7 Conclusions. References. 18. Bluetooth Security (Christian Gehrmann). 18.1 Introduction. 18.2 Bluetooth Wireless Technology. 18.3 Security Architecture. 18.4 Security Weaknesses and Countermeasures. 18.5 Bluetooth Security: What Comes Next? References. 19. Mobile Telecom Networks (Christos Xenakis and Lazaros Merakos). 19.1 Introduction. 19.2 Architectures Network. 19.3 Security Architectures. 19.4 Research Issues. 19.5 Conclusions. References. 20. Security in Mobile Ad HocNetworks (Mike Burmester, Panayiotis Kotznanikolaou, and Christos Douligeris). 20.1 Introduction. 20.2 Routing Protocols. 20.3 Security Vulnerabilities. 20.4 Preventing Attacks in MANETs. 20.5 Trust in MANETs. 20.6 Establishing Secure Routes in a MANET. 20.7 Cryptographic Tools for MANETs. References. 21. Wireless Sensor Networks (Artemios G. Voyiatzis and Dimitrios N. Serpanos). 21.1 Introduction. 21.2 Sensor Devices. 21.3 Sensor Network Security. 21.4 Future Directions. 21.5 Conclusions. References. 22. Trust (Lidong Chen). 22.1 Introduction. 22.2 What Is a trust Model? 22.3 How Trust Models Work? 22.4 Where Trust Can Go Wrong? 22.5 Why Is It Diffi cult to Defi ne Trust? 22.6 Which Lessons Have We Learned? References. Part Four Trust, Anonymity, and Privacy. 23. PKI Systems (Nikos Komninos). 23.1 Introduction. 23.2 Origins of Cryptography. 23.3 Overview of PKI Systems. 23.4 Components of PKI Systems. 23.5 Procedures of PKI Systems. 23.6 Current and Future Aspects of PKI Systems. 23.7 Conclusions. References. 24. Privacy in Electronic Communications (Alf Zugenmaier and Joris Claessens). 24.1 Introduction. 24.2 Protection from Third Party: Confidentiality. 24.3 Protection from Communication Partner. 24.4 Invasions of Electronic Private Sphere. 24.5 Balancing Privacy with Other Needs. 24.6 Structure of Privacy. 24.7 Conclusion and Future Trends. References. 25. Securing Digital Content (Magda M. Mourad and Ahmed N. Tantawy). 25.1 Introduction. 25.2 Securing Digital Content: Need and Challenges. 25.3 Content Protection Techniques. 25.4 Illustrative Application: EPublishing of E-Learning Content. 25.5 Concluding Remarks. References. Appendix A. Cryptography Primer: Introduction to Cryptographic Principles and Algorithms (Panayiotis Kotzanikolaou and Christos Douligeris). A.1 Introduction. A.2 Cryptographic Primitives. A.3 Symmetric-Key Cryptography. A.4 Asymmetric-Key Cryptography. A.5 Key Management. A.6. Conclusions and Other Fields of Cryptography. References. Appendix B. Network Security: Overview of Current Legal and Policy Issues (Andreas Mitrakas). B.1 Introduction. B.2 Network Security as a Legal Requirement. B.3 Network Security Policy Overview. B.4 Legal Aspects of Network Security. B.5 Self-Regulatory Security Frameworks. B.6 Conclusions. References. Appendix C. Standards in Network Security (Despina Polemi and Panagiotis Sklavos). C.1 Introduction. C.2 Virtual Private Networks: Internet Protocol Security (IPSec). C.3 Multicast Security (MSEC). C.4 Transport Layer Security (TLS). C.5 Routing Security. C.6 ATM Networks Security. C.7 Third-Generation (3G) Mobile Networks. C.8 Wireless LAN (802.11) Security. C.9 E-Mail Security. C.10 Public-Key Infrastructure (X.509). Index. About the Editors and Authors.