Christos Michalakelis

Harokopio University | HUA · Department of Informatics and Telematics

The cloud broker is an IT role and a business model that acts as an intermediary agent between cloud providers and end users. The exponentially increasing adoption of the IaaS market has contributed significantly to the so far growth of the Cloud Broker market. The unprecedented scenario of COVID-19 pandemic has upgraded the role and the contributi...

Model-based systems design (MBSD), a current trend adopted by INCOSE, employs the systems modeling language (SysML), a standard introduced by OMG and INCOSE. Though there are numerous works on integrating performance exploitation in SysML, cost is not sufficiently explored as a driving design parameter. By integrating cost analysis in a popular mod...

As consumers progressively turn to e-commerce for all their shopping needs, on time delivery is of major importance. Logistics companies struggle to find strategies that improve efficiency and reduce costs. Drone-based distribution is an alternative for last mile delivery, gaining popularity, as it can provide reliable and safe services. In this pa...

Container-as-a-service (CaaS) is a business model that facilitates software developers in organizing, running, managing, and deploying applications using container-based virtualization. The CaaS market is a fast-growing one, leading infrastructure-as-a-service (IaaS) providers into offering CaaS solutions built on top of their IaaS platforms. Given...

It is commonly accepted that the COVID-19 pandemic has had a crucial effect on many aspects of people’s lives. The limitations placed on human relations have also affected education. The mandatory implementation of e-learning and the use of the information and communication technology tools in the teaching process have been the most important chang...

As consumers progressively turn to e-commerce for all their shopping needs, on time delivery is of major importance. Logistics companies struggle to find strategies that improve efficiency and reduce costs. Drone-based distribution is an alternative for last mile delivery, gaining popularity, as it can provide reliable and safe services. In this pa...

Cloud TV will play an important role in future pay TV services and is quickly becoming the next arena for TV content providers. This emphasizes the need for a technology roadmap in order to address several key issues that may affect the deployment of future Cloud TV services. Three alternative technologies, namely Internet Protocol TV (IPTV), Over...

The study of innovation has been thoroughly investigated over the past five decades by many researchers and organizations. Educational innovation, in particular, has been studied since the 1970s more systematically. Educational innovation, its adoption and implementation have been studied not only by various researchers, namely Fullan, Westera, Coh...

Smart Home (SH) systems are considered one of the prominent applications in the era of Internet of Things (IoT), where it is possible to control home devices to achieve a better usage in terms of cost and convenience. IoT offers the internet connection and remote management of home automation, integrated with numerous sensors. SHs constitute to be...

When exploring hybrid cloud solutions, the provision of cloud computing resources by more than one provider, may result in important gains, such as better risk management, improvement of operational efficiency and avoidance of the lock-in effect by a single vendor. To this end, many enterprises decide to rely on hybrid strategies and multiple cloud...

Industry 4.0 is expected to deliver significant productivity gain taking advantage of Internet of things (IoT). Smart solutions, enhanced by IoT, are constantly driving revolutionary approaches in multiple domains. Smart factories are one domain where intelligent integrated robotic systems will revolutionize manufacturing, resulting in a complex ec...

Cloud computing is a rapidly evolving computational model, which has succeeded in transforming the ICT industry and the economy's production techniques by making corresponding services even more accessible to businesses, offering cost-effective solutions. The cloud broker is a new business model, derived from the necessity of finding the best provi...

There is robust evidence that homelessness and the associated life conditions of a homeless person may cause and exacerbate a wide range of health problems, while healthcare for the homeless is simultaneously limited in accessibility, availability, and appropriateness. This article investigates legal frameworks of health care provision, existing kn...

Following the increasing need for higher broadband speeds, the European Commission (EC) has set specific goals to all member states regarding the development of new generation networks. Due to the high deployment cost, many countries have adopted only a partial transition to a purely optical fiber network. Fiber-to-the-Cabinet (FttC) architecture c...

This article, as part of the 'SUMcity' research program, aims to give a comprehensive account of the regeneration that occurred in Athens by the adaptive reuse of the old FIX Brewery to house the new Hellenic National Museum of Contemporary Art (EMST). Adaptive reuse is an urban sustainability development evolving process, used to manage assets and...

Cloud TV is a cloud-based live television streaming program or app, allowing the user to watch high definition (HD) TV channels without the requirement of a TV box or aerial but only a stable internet connection. As the number of Cloud TV channels continuously increases, so does the need for a techno-economic evaluation and analysis, which constitu...

The phenomenon of homelessness or loss of housing is a social problem faced by both the developed and the developing world. The fact that in many countries there is no reliable data on the homeless is a major problem for the development of coherent policies and strategies to tackle the problem. There is often a weakness in the clear definition of t...

Cloud TV will play an important role in future pay-TV services and is quickly becoming the next arena for TV content providers. This emphasizes the need for a technology roadmap to address several key issues that may affect the deployment of future Cloud TV services. Taking into account an important blend of social, economic and technological facto...

Cloud computing has rapidly transformed ICT industry and numerous cloud providers offer multiple flavors of Infrastructure-as-a-Service solutions (IaaS), aiming at meeting customer demand within a competitive landscape. In addition, cloud users seek the optimal cloud service and usually end-up choosing solutions based mainly on price. Pricing strat...

The Internet of Things (IoT) has been hailed as the next best industrial revolution and is expected to influence the global economy. The tide has begun to shift away from old ways and several companies are working towards providing novel IoT applications and development solutions, which will change the way we approach everyday tasks in the future....

Cloud computing is gaining ground in the global ICT market and day by day a significant number of Small and Medium Enterprises (SMEs) are adopting cloud services with sole purpose to improve their business environment and become more efficient, competitive and productive. Migrating a business IT infrastructure to the cloud offers reduction on serve...

Cloud computing is a growing industry and it has already dominated many IT markets segments. Cloud providers offer numerous equivalent IaaS services aiming to fulfill clients' requirements. In addition, cloud clients need to choose solutions that minimize costs without compromising efficiency though. However, not only the confusion due to the large...

Cloud computing is gaining ground in the global ICT market and day by day a significant number of Small and Medium Enterprises (SMEs) are adopting cloud services with sole purpose to improve their business environment and become more efficient, competitive and productive. Migrating a business IT infrastructure to the cloud offers reduction on serve...

Primary objective of this research is the development of a webportal for the State Administrative Entities Sustainable Development, with respect to standards provided by the relevant business sustainability reports. Through this website Cities will be able to record their performance, anticipate and manage changes while setting goals in order to im...

The issue of how to obtain an accurate short-term forecast in the beginning stage of the technological diffusion is of great importance for policy makers, researchers and managers. Time-series forecasting has been noticeably neglected in the specific research area due to the prerequisite of having enough data in order to create a time-series. In th...

Cloud computing is a rapidly evolving computational model, which has succeeded in transforming the ICT industry and the economy's production techniques by making corresponding services even more accessible to businesses, offering cost-effective solutions. The cloud broker is a new business model, derived from the necessity of finding the best provi...

Infrastructure as a Service (IaaS) is a rapidly expanding model of cloud computing. It includes control of computing resources, such as memory, computing power and storage capacity, satisfying the most fundamental IT needs for businesses on a usage-based payment model. Currently, there is an increased demand for IaaS services, which in turn feeds c...

In a fluctuating political environment, policy makers seek solutions that will meet multiple objectives, often prioritizing one over the other in a matter of days, under the pressure of public opinion. This is the context of the political landscape to which millions of refugees found themselves entangled during the last few years. War, injustice, s...

The Greek Asylum Service has been operational for four years, in an environment characterized by rapid developments. The movement of refugees and migrants to Europe, was probably the defining development for our continent in the last two years. In 2015, the great unforeseen refugee influx led to the expansion of the Asylum Service. Our country is l...

The global financial crisis, the efforts for recovery from the recession, as well as the globalization of the economy-which significantly increased completion in the international market-created the need for exploration of new sources of development and new sustainable ways for economic progress. An important tool that can be used to pursue the eco...

Cloud computing, as an innovative business model, has experienced rapid diffusion across the international business world, offering many benefits to both the demand and the supply side of the ICT market. In particular, the public cloud approach receives more attention and the Infrastructure as a Service (IaaS) model is expected to be the fastest gr...

Cloud computing has succeeded in transforming the ICT industry, making computing services more accessible to businesses. Nowadays, many cost effective solutions are available to users. However, searching for the best provider or the best bundle is not always an easy decision for the client. The cloud broker is a widely known business model derived...

REMINDER - CALL FOR PAPERS Cloud Computing Technoeconomic Engineering Workshop in conjunction with the IEEE International Conference on Cloud Engineering (IC2E) 2016. 4-8 April 2016, Berlin DEADLINES EXTENDED Paper Submission deadline: December 10 2015 Notification: January 31 2016 Camera ready: February 29 2016 For complete information, visit...

Cloud computing has succeeded in transforming the ICT industry, making software and hardware services even more accessible to businesses and establishing an environment for rapid innovation. Since cloud computing is an innovative business model, whose deployment is accompanied by huge investments, a thorough, multilevel cost analysis of provided se...

The aims of this research are to explore and evaluate the nature of the relationship between open source software (OSS) and eGovernment maturity, as well as the factors impacting their development at a national level. The study proposes a theoretical framework, under the prism of which socio-economic, technological and institutional factors critica...

Cloud computing, is a rapidly evolving type of internet- based computing model that relies on sharing computing resources, rather than having local servers or personnel to handle them. It has already been adopted by a significant number of Small and Medium Enterprises (SMEs) as a business advantage able to improve their business environment and hel...

Cloud computing is a modern style of innovation in network environment which takes the advantage of multi-technologies as distributed systems, wireless communication, parallel processing in term of providing service architecture. The main services are concerned about sharing communication and resources. Cloud computing offers scalable access, elast...

Under the present economic recession, much discussion is made regarding income increase. New technologies and broadband communications in particular can yield comparative advantages in countries. Based on the assumption that income increase is related to broadband penetration, a Granger causality test is applied in 86 countries worldwide. The causa...

Cloud computing is an innovative business model, being developed at a fast pace during the last years, offering many operational and economic benefits to both the demand and the supply side of the ICT market. Infrastructure as a Service (IaaS), which includes control of fundamental computing resources, is expected to be the fastest growing model of...

The issue of how to obtain an accurate short-term forecast in the beginning stage of the technological diffusion is of great importance for policy makers, researchers and managers. Time-series forecasting has been noticeably neglected in the specific research area due to the prerequisite of having enough data in order to create a time-series. In th...

Many scheduling algorithms for workflow applications target a single application at each time. The degree of parallelism of the application depends on the workflow structure, and for a task parallelism approach, the degree of parallelism will determine the degree of utilization of the resources reserved for the application. As today's computing nod...

The aim of this paper is to investigate and evaluate the critical factors that underlie the Open Source Software (OSS) diffusion among countries. Grounded on a theoretical framework of diffusion of innovations theory and the theories of institutionalism, endogenous and exogenous growth, the study proposes a parameterized diffusion model that evalua...

The current economic crisis in Europe generated the need for new models of development, with Small-Medium Enterprises (SMEs) being a key solution and a growth driver. This could be achieved by the promotion of technological innovation, as for example by the means of the cloud computing business model. Cloud computing is a rapidly evolving computati...

The steady growth of broadband penetration and the ongoing progress in networking technologies have increased the importance of home networks in the provision of high quality internet services. Market stakeholders have cooperated to evolve home networking towards an integrated, converged Gigabit technology, which will completely change the Home Are...

This study focuses on theory building providing a holistic conceptual framework that consists of an ontology based OSS business model and an OSS business model taxonomy. The study extends existing theory in OSS business models and corresponding taxonomies, based on the structured-case methodological approach. An exploratory study is conducted in tw...

The use of information and communications technology (ICT) turned out to be a key factor in the process of the wider development of a country. It is therefore very useful to estimate ICT evolution by the means of an appropriate metric. Based on statistical data from 159 countries, the ICT maturity level index (IMLI) is proposed and estimated by usi...

This study contributes to the current literature of eGovernment adoption, by proposing a parsimonious, yet comprehensive model, based on three socio-economic theories namely, institutionalism, endogenous and exogenous growth. Using this framework as the guiding theoretical lens, critical factors are identified, while their impact is evaluated with...

Diffusion modeling is rather broad in nature, and is important in the areas of estimation and forecasting. Conventional models do not incorporate parameters that explicitly take into account the size of the population, or, equivalently, the size of the potential market. As a consequence, the models often fail to provide accurate forecasts, especial...

Technological adoption, with an emphasis on Information and Communications technology (ICT), is considered as a decisive factor for the overall development of each country. For this, the European Commission (EC) has launched a number of policy frameworks, aiming to enhance the usage and to improve the quality of European citizens' lives. However an...

A theoretical framework is proposed for the better understanding of the OSS global diffusion. Following a case study approach, the Apache web server's market potential is estimated, forecasted and examined in terms of the socio-economic factors determining its diffusion, across different economic environments in developed versus developing countrie...

The diffusion of broadband in Europe is shaped by the penetration rates of the individual European countries. However, the contribution of each country to the total level of diffusion is not the same, due to the existence of a digital divide among the countries. The digital divide is still evident and although diffusion keeps increasing, not all co...

Based on concepts of ecology modeling and specifically on population biology, a methodology for describing a high-technology market's dynamics is developed and presented. The importance of the aforementioned methodology is its capability to estimate and forecast the degree of competition, market equilibrium, and market concentration, the latter exp...

The innovation diffusion literature has established that the spread of a successful innovation over time typically follows a sigmoid curve. Therefore, the forecasting in this area has been monopolized by the use of well known aggregate diffusion models. Time series forecasting has been surprisingly neglected, as it provides mainly accurate short te...

This study focuses on theory building providing a holistic conceptual framework that consists of an ontology based OSS business model and an OSS business model taxonomy. The study extends existing theory in OSS business models and corresponding taxonomies, based on the structured-case methodological approach. An exploratory study is conducted in tw...

This paper aims to propose a new framework for estimating and forecasting diffusion of high technology products, along with the construction of a price index. Into that context, the “diffusion–price” model is presented, as an innovative concept providing a long term estimation of both price and diffusion elasticity. This corresponds to the bidirect...

The objective of the present research is to build an empirical Lotka-Volterra system using real-time data and information from the postpaid and prepaid mobile telecommunications subscribers in the OECD area. Genetic algorithms are used in order to specify the appropriate coefficients of the corresponding predator-prey competition system, where the...

Forecasting diffusion of new technologies is usually performed by the means of aggregate diffusion models, which tend to monopolize this area of research and practice, making the alternative approaches, like the Box-Jenkins, less favourable choices due to their lack of providing accurate long-term predictions. This paper presents a new methodology...

Markets of high technology products and services, such as telecommunications, are described by fast technological changes and rapid generational substitutions. Since the conventional modeling approaches that are based on diffusion models do not usually incorporate this important aspect into their formulations, the accuracy of the provided forecasts...

Home networks (HNs) are rapidly becoming the next battlefield for various telecom carriers and companies. The European project ICT-OMEGA seeks to enable the convergence of the diverse wireless and wireline technologies at the Medium Access Control (MAC) layer. In such a world of converging, heterogeneous HN technologies, system designers needs to t...