Dimitar Trajanov

Ad hoc networks connection availability modeling

One of the most important issues for mobile ad hoc networks is to know the availability of the system. In this paper we propose a generalized connection availability model based on real measurable parameters that concern the performances of mobile ad hoc networks. Detailed validation of the connection availability model is presented through simulations. The proposed model can be used for analysis or design of an ad hoc network that needs to satisfy a given connection availability level.

Grid Computing Implementation in Ad Hoc Networks

The development of ubiquitous computing and mobility opens challenges for implementation of grid computing in ad hoc network environments. In this paper, a new grid computing implementation for ad hoc networks is proposed. The proposed addition of the ad hoc network protocols suite offers an easy and effective way to exploit the computing power of the network nodes. The model is implemented in the NS-2 network simulator providing the possibility to investigate its performances and tune the network grid parameters.

Terrain-aware three-dimensional radio-propagation model extension for NS-2

One of the weakest points of modeling wireless systems is radio-signal propagation in an irregular space. For that reason, it is essential that, when analyzing the performances of wireless networks, we observe the network in a natural three-dimensional terrain and we use an appropriate propagation model. However, care must be taken since such simulations demand extensive processing power, especially for mobile scenarios. In this paper, we present an extension for the NS-2 simulator with our optimized Durkin’s propagation model based on digital elevation model data. Going one step further in creating a set of realistic simulation environments, we present a case study for modeling the behavior of a wireless ad hoc network via the social network of users grouped into scale-free communities. The case study presents a blend of topography responsive simulations with realistic traffic and movement pattern, while showing the numerous simulation possibilities of the presented extension.

Analysis of small world phenomena and group mobility in ad hoc networks

The main application of wireless mobile ad hoc networks is to offer services for situations wherein groups of people come together and share information. The groups of people that use the ad hoc network form some kind of social network. In this paper an analysis of the performances of mobile ad hoc networks is performed when taking into consideration its social characteristics through the small world phenomena of the application layer and usage of group-based mobility. The simulations show that the social interconnection between the network users has an extreme influence on the network performances. The results bring forth a different view on the real life deployment of ad hoc networks when compared to the poor performances of the purely randomized scenarios.

Durkin’s Propagation Model Based on Triangular Irregular Network Terrain

Propagation models that are commonly used in assessing the performances of ad hoc networks, take into account the mechanisms of reflection, diffraction and scattering on the ground. However, it must not be forgotten that the communication between devices is usually carried out in irregular terrain, so it’s necessary to use the terrain profile in order to determine the signal coverage. In this paper we layout the extension of the Durkin’s propagation model using Triangular Irregular Network (TIN) based terrain. The verification of the proposed propagation model is done by comparing the results with the ones obtained with a SRTM map used in the Radio Mobile software.

ISO-Standardized Smart City Platform Architecture and Dashboard

A concept guided by the ISO 37120 standard for city services and quality of life is suggested as unified framework for smart city dashboards. The slow (annual, quarterly, or monthly) ISO 37120 indicators are enhanced and complemented with more detailed and person-centric indicators that can further accelerate the transition toward smart cities. The architecture supports three tasks: acquire and manage data from heterogeneous sensors; process data originated from heterogeneous sources (sensors, OpenData, social data, blogs, news, and so on); and implement such collection and processing on the cloud. A prototype application based on the proposed architecture concept is developed for the city of Skopje, Macedonia. This article is part of a special issue on smart cities.

Performances of clustered ad hoc networks on 3D terrains

Propagation prediction algorithms which use terrain information are typically used for the design of modern wireless systems. Therefore, it is essential that when analyzing the performances of ad hoc networks we observe the network in a natural 3D terrain and we use an appropriate propagation model. In this paper we explain our extension of the NS-2 simulator using Digital Elevation Model data and terrain aware propagation model. Because of the natural emergence of clustering in the network of users, we also study the relationship between the clustering in the ad hoc networks and different terrain profiles. The simulations show that, when the network clusters are accompanied with related terrain contours, the observed network performances demonstrate measurable enhancement.

Inferring Cuisine - Drug Interactions Using the Linked Data Approach

Food - drug interactions are well studied, however much less is known about cuisine - drug interactions. Non-native cuisines are becoming increasingly more popular as they are available in (almost) all regions in the world. Here we address the problem of how known negative food - drug interactions are spread in different cuisines. We show that different drug categories have different distribution of the negative effects in different parts of the world. The effects certain ingredients have on different drug categories and in different cuisines are also analyzed. This analysis is aimed towards stressing out the importance of cuisine - drug interactions for patients which are being administered drugs with known negative food interactions. A patient being under a treatment with one such drug should be advised not only about the possible negative food - drug interactions, but also about the cuisines that could be avoided from the patients diet.

Game Theoretic Approach for Discovering Vulnerable Links in Complex Networks

Complex networks have been an up-and-coming exciting field in the realm of interactions. With their widespread use appearing on the horizon it is ever more vital to be able to measure their vulnerability as a function of their topology. Precisely, discovering vulnerable links, disposed to attacks, can help in hardening these links and by that providing more secure and reliable network structure. This paper addresses the link vulnerability of different topologies of complex networks such as: random networks, geographic random networks, small world networks and scale-free networks. We introduce measure for vulnerability of complex networks, and prove by simulations that network vulnerability heavily depends on the network topology.

Consolidating drug data on a global scale using Linked Data

BackgroundDrug product data is available on the Web in a distributed fashion. The reasons lie within the regulatory domains, which exist on a national level. As a consequence, the drug data available on the Web are independently curated by national institutions from each country, leaving the data in varying languages, with a varying structure, granularity level and format, on different locations on the Web. Therefore, one of the main challenges in the realm of drug data is the consolidation and integration of large amounts of heterogeneous data into a comprehensive dataspace, for the purpose of developing data-driven applications. In recent years, the adoption of the Linked Data principles has enabled data publishers to provide structured data on the Web and contextually interlink them with other public datasets, effectively de-siloing them. Defining methodological guidelines and specialized tools for generating Linked Data in the drug domain, applicable on a global scale, is a crucial step to achieving the necessary levels of data consolidation and alignment needed for the development of a global dataset of drug product data. This dataset would then enable a myriad of new usage scenarios, which can, for instance, provide insight into the global availability of different drug categories in different parts of the world.ResultsWe developed a methodology and a set of tools which support the process of generating Linked Data in the drug domain. Using them, we generated the LinkedDrugs dataset by seamlessly transforming, consolidating and publishing high-quality, 5-star Linked Drug Data from twenty-three countries, containing over 248,000 drug products, over 99,000,000 RDF triples and over 278,000 links to generic drugs from the LOD Cloud. Using the linked nature of the dataset, we demonstrate its ability to support advanced usage scenarios in the drug domain.ConclusionsThe process of generating the LinkedDrugs dataset demonstrates the applicability of the methodological guidelines and the supporting tools in transforming drug product data from various, independent and distributed sources, into a comprehensive Linked Drug Data dataset. The presented user-centric and analytical usage scenarios over the dataset show the advantages of having a de-siloed, consolidated and comprehensive dataspace of drug data available via the existing infrastructure of the Web.