Nikolaos Doukas

Bio: Nikolaos Doukas is an academic researcher from Army and Navy Academy. The author has contributed to research in topics: Error detection and correction & Checksum. The author has an hindex of 7, co-authored 39 publications receiving 162 citations. Previous affiliations of Nikolaos Doukas include National Technical University of Athens & Hellenic Air Force Academy.

Routing optimization heuristics algorithms for urban solid waste transportation management

Abstract: During the last decade, metaheuristics have become increasingly popular for effectively confronting difficult combinatorial optimization problems. In the present paper, two individual meatheuristic algorithmic solutions, the ArcGIS Network Analyst and the Ant Colony System (ACS) algorithm, are introduced, implemented and discussed for the identification of optimal routes in the case of Municipal Solid Waste (MSW) collection. Both proposed applications are based on a geo-referenced spatial database supported by a Geographic Information System (GIS). GIS are increasingly becoming a central element for coordinating, planning and managing transportation systems, and so in collaboration with combinatorial optimization techniques they can be used to improve aspects of transit planning in urban regions. Here, the GIS takes into account all the required parameters for the MSW collection (i.e. positions of waste bins, road network and the related traffic, truck capacities, etc) and its desktop users are able to model realistic network conditions and scenarios. In this case, the simulation consists of scenarios of visiting varied waste collection spots in the Municipality of Athens (MoA). The user, in both applications, is able to define or modify all the required dynamic factors for the creation of an initial scenario, and by modifying these particular parameters, alternative scenarios can be generated. Finally, the optimal solution is estimated by each routing optimization algorithm, followed by a comparison between these two algorithmic approaches on the newly designed collection routes. Furthermore, the proposed interactive design of both approaches has potential application in many other environmental planning and management problems.

A blind source separation based cryptography scheme for mobile military communication applications

Abstract: Security in digital transmission is an increasingly interesting topic in a number of fields. In many cases however, the need for security is forfeited due to the high complexity of commonly used cryptosystems. The use of the underdetermined source separation problem as a basis for a cryptographic mechanism has recently been proposed. Many cryptographic algorithms, such as public key algorithms which based a common military application, use as a basis intractable number theory problems (such as integer factorization and exponentiation). Underdetermined blind source separation is also shown to have the potential to serve this purpose, as the difficulties of deriving an analytic solution to this problem have been extensively documented. This paper presents a study of blind source separation based encryption, proposes some further improvements in approaches that have already been presented and illustrates the application of the improved algorithms in the paradigm of secure speech communication. The proposed scheme is related to Independent Component Analysis Concepts. A preliminary cryptanalysis study is presented that verifies the adequacy of the new scheme for use in mobile military communication units and other applications where security is critical. The proposed scheme is also shown to be immune to some of the attacks to which existing methods were believed to be vulnerable.

Fast subscriber identification based on the zero knowledge principle for multimedia content distribution

Abstract: In this article, an innovative method is proposed for the realisation of zero knowledge subscriber identification schemes that is suitable for multimedia content distribution applications. The fundamental principle underlying the proposed method is the concept of using one-way Boolean functions as transformations for the zero knowledge identification. This enables the increase of the speed of completion of the identification process by two to three orders of magnitude, compared to the corresponding speed when using modular arithmetic with large numbers. A method for the establishment of one way Boolean functions for zero knowledge identification has been developed. Two examples for the application of the proposed method are presented.

True random number generation based on environmental noise measurements for military applications

Abstract: True random number generators can significantly contribute to the development of high security cryptographic schemes, such as those required for use in military applications. This article presents some the results of an innovative method for the generation of truly random number sequences, based on environmental noise measurements. The statistical properties of different noise types have been studied. Based on this study, an efficient random number generator has been developed that uses signals from the built in microphone that is ubiquitous most current personal computers and other personal information processing systems. Statistical measures have been determined that measure the randomness qualities of the output sequence. These measures have been studied for different input noise properties. The merit of the proposed generator in terms of the rate at which random numbers are produced has also been assessed.

PORs: Proofs of Retrievability for Large Files

Abstract: In this paper, we define and explore proofs of retrievability (PORs). A POR scheme enables an archive or back-up service (prover) to produce a concise proof that a user (verifier) can retrieve a target file F, that is, that the archive retains and reliably transmits file data sufficient for the user to recover F in its entirety.A POR may be viewed as a kind of cryptographic proof of knowledge (POK), but one specially designed to handle a large file (or bitstring) F. We explore POR protocols here in which the communication costs, number of memory accesses for the prover, and storage requirements of the user (verifier) are small parameters essentially independent of the length of F. In addition to proposing new, practical POR constructions, we explore implementation considerations and optimizations that bear on previously explored, related schemes.In a POR, unlike a POK, neither the prover nor the verifier need actually have knowledge of F. PORs give rise to a new and unusual security definition whose formulation is another contribution of our work.We view PORs as an important tool for semi-trusted online archives. Existing cryptographic techniques help users ensure the privacy and integrity of files they retrieve. It is also natural, however, for users to want to verify that archives do not delete or modify files prior to retrieval. The goal of a POR is to accomplish these checks without users having to download the files themselves. A POR can also provide quality-of-service guarantees, i.e., show that a file is retrievable within a certain time bound.

A GIS based model for the optimisation of municipal solid waste collection: the case study of Nikea, Athens, Greece

Abstract: Waste collection and transpor t (WC&T) constitutes a large fraction of the total municipal solid waste (MSW) management costs worldwide. In Greece currently this may account for 70-100% of the total MSW costs, most of it being spent on salaries and fuel. It is therefore crucial to improve the WC&T system through routing optimisation. Geographic Information System (GIS) technology provides an advanced modelling framework for decision makers in order to analyse and simulate various spatial waste management problems, including waste collection. In this study a methodology for the optimisation of the waste collection and transport system, based on GIS, was developed. A model in ArcGIS Network Analyst was developed in order to improve the efficiency of WC&T in the Municipality of Nikea (MoN), Athens, Greece via the reallocation of waste collection bins and the optimisation of vehicle routing in terms of distance and time travelled. Two scenarios were compared with the current empirical collection scheme: S1-collection vehicle routing optimisation, and S2-reallocation of bins and routing optimisation. Results demonstrate that both scenarios provided savings compared to the current situation in terms of collection time (3.0% and 17.0% for S1 and S2 respectively) and travel distance (5.5% and 12.5% for S1 and S2 respectively). Time and distance reduction relate to similar CO2 emissions and fuel consumption savings. These figures indicate that GIS based models can offer significant improvements to the WC&T system and, consequently, to its financial and environmental costs.