Papers by Yannis Pollalis
INTERNATIONAL CONFERENCE OF COMPUTATIONAL METHODS IN SCIENCES AND ENGINEERING 2009: (ICCMSE 2009), 2012
In several cases, a competitive market can be simulated by a game, where each company/opponent is... more In several cases, a competitive market can be simulated by a game, where each company/opponent is referred to as a player. In order to accommodate the fact that each player (alone or with alliances) is working against some others' interest, the rather conservative maximin criterion is frequently used for selecting the strategy or the combination of strategies that yield the best of the worst possible outcomes for each one of the players. Under this criterion, an optimal solution is obtained when neither player finds it beneficial to alter his strategy, which means that an equilibrium has been achieved, giving also the value of the game. If conditions change as regards a player, e.g., because of either achieving an unexpected successful result in developing an innovative industrial product or obtaining higher liquidity permitting him to increase advertisement in order to acquire a larger market share, then a new equilibrium is reached. The identification of the path between the old and the new equilibrium ...
INTERNATIONAL CONFERENCE OF COMPUTATIONAL METHODS IN SCIENCES AND ENGINEERING 2009: (ICCMSE 2009), 2012
In this paper, optimal environmental policy for reclamation of land unearthed in lignite mines is... more In this paper, optimal environmental policy for reclamation of land unearthed in lignite mines is defined as a strategic target. The tactics concerning the achievement of this target, includes estimation of optimal time lag between each lignite site (which is a segment of the whole lignite field) complete exploitation and its reclamation. Subsidizing of reclamation has been determined as a function of this time lag and relevant implementation is presented for parameter values valid for the Greek economy. We proved that the methodology we have developed gives reasonable quantitative results within the norms imposed by legislation. Moreover, the interconnection between strategy and tactics becomes evident, since the former causes the latter by deduction and the latter revises the former by induction in the time course of land reclamation.
While there have been vast changes in information systems (IS) management practices over recent d... more While there have been vast changes in information systems (IS) management practices over recent decades, there has been only modest change in the ways that IS researchers analyze the impact ofIS on organizational performance. Various studies that have addressed the "productivity paradox" have produced widely divergent results that have often been at odds with the intuition of IS practitioners and with a wealth of existing anecdotal evidence. A few studies have begun to view the impact of IT on the organization in more sophisticated ways (7, 9). However, the preponderance of IS studies employ contingency models that have produced results that often reflect a wide gap between organizational reality and researched reality. This study has the objective of demonstrating an alternative paradigm that appears to have a better chance of detecting the complex relationships among the qualitatively distinct factors that combine to determine organizational performance. That approach is a holistic one that is based on the notion of gestalts from Gestalt psychology. The study also has the objective of demonstrating how useful and managerially relevant inferences can be made using such holistic analyses.
European Journal of Operational Research, Mar 1, 2009
Adaptability to each separate user's needs and preferences is a common concern in modern e-learni... more Adaptability to each separate user's needs and preferences is a common concern in modern e-learning systems. Among various adaptation techniques described in recent research, collaboration support seeks to create groups that efficiently work together in order to advance user's learning. This paper defines two similarity coefficients between users and learning objects and focuses on automatic creation of properly matching collaborating groups based on an algorithmic approach. By adopting methods derived from Group Technology, the method simultaneously selects appropriate learning objects to form a corresponding educational package for each group, thus assuring optimal value of user's learning.
Archives of Business Research, Jun 11, 2021
This research focuses on providing insights for a solution for collecting, storing, analyzing and... more This research focuses on providing insights for a solution for collecting, storing, analyzing and visualizing data from customer energy consumption patterns. The data analysis part of our research provides the models for knowledge discovery that can be used to improve energy efficiency at both producer and consumer ends. Τhe study sets a new analytical framework for assessing the role of behavioral knowledge in energy efficiency using a wide range of Case Studies, Experiments, Research, Information and Communication Technologies (ICT) in combination with the most modern econometric methods and large analytical data taking into account the characteristics of the study participants (household energy customers).
The purpose of the present research study is to evaluate the quality of life of patients with mus... more The purpose of the present research study is to evaluate the quality of life of patients with musculoskeletal problems of the Spinal Column before and after surgery with the use of the EQ-5D-5L health status questionnaire. MATERIALS-METHODS: The research is based on primary data collection of 27 patients who completed the questionnaires at three different times: a) preoperatively; that is, after completion of conservative treatment which involved medication, physiotherapy, etc., b) ten days postoperatively and c) immediately after the first post-operative month. RESULTS: Out of the 27 patients, aged between 34 and 79 years (mean age 52±15,07) who participated in this study, 11 were males (40,7%) while 16 were females (59,3%). 48,1% of the patients suffered from a herniated intervertebral disc in the lumbar region, 18,5% from symptomatic degenerative disc disease (DDD or black disc), 18,5% from a herniated intervertebral disc in the cervical region and the remaining 14,8% from spondylolisthesis in the lumbar region. Total improvement of the quality of life (QoL) in our study was on average 0,6 QALYs at 10 days and 0,83 QALYs at 30 days. The total average direct cost of these surgical interventions amounted to 7413,1±3062,9 while the index of cost-utility for the sample population was estimated to be 12355,2 euro/ QALY at 10 days. This index decreased considerably to 8931,4 euro/ QALY at 30 days after the surgical intervention since the average benefit in QALYs increased and the QoL improved. CONCLUSIONS: The results of the present study point out the great utility of surgical interventions in the spinal column to treat patients' common symptoms (low back pain with or without sciatica) with complications being nearly next to zero. By means of the EQ-5D-5L health status questionnaire, the comparative study of patients' QoL both before and after surgical treatment reveals statistically considerable improvement at 10 and 30 days following the surgery. Finally, this study has led to useful conclusions: a) the modern technique of discoplasty is rather more efficient than percutaneous spinal fusion for the treatment of lumbago from degenerative disc disease in the lumbar region, b) conservative treatment of spinal column problems is rather less efficient than surgical treatment and c) modern surgery of the spinal column in Greece is rather more efficient than in other modern Health Systems.
Nucleation and Atmospheric Aerosols, 2007
This work deals with the determination of capital cost in wastewater treatment installations oper... more This work deals with the determination of capital cost in wastewater treatment installations operating under inflow characteristics uncertainty. For this purpose, a methodological framework, under the form of an algorithmic procedure, has been designed/developed and successfully implemented in two cases of biological processing under steady state conditions. The results obtained are in satisfactory approximation with industrial data. Moreover, mathematical formulae have been derived for determining capital cost when processing takes place under unsteady state conditions; in this case, numerical approximation is necessary, since the expressions obtained have not analytic solution. Last, the influence of certain technical parameters on minimum capital cost is discussed.
Journal of health & medical economics, 2016
Central European Management Journal, Jun 15, 2021
Purpose: This article aims to assess strategy and technology as key drivers of Greek businesses' ... more Purpose: This article aims to assess strategy and technology as key drivers of Greek businesses' digital transformation and compare the results to those of international studies and sources. Methodology: A research was conducted on 124 Greek businesses from different sectors and industries with the use of an anonymous questionnaire from December 2019 to January 2020. Greek businesses were categorized as early, developing, and maturing according to their perceptions about the level of their digital maturity, and differences were identified. The results were finally compared to an international relevant survey. Findings: Several differences were located among the Greek businesses of the three digital maturity categories as formulated after their self-evaluation, and evolution has been identified on their perceptions about their digital strategy, its existence, objectives, and structure, which can be seen developing and expanding from the lowest to the highest levels of digital maturity. Originality: The findings can be useful in creating an initial picture of the perceptions and practices applied by Greek businesses to their use of digital technologies. They can also become a measure of comparison for the self-evaluation of Greek businesses in their efforts to digitally transform.
Information Resources Management Journal, 1991
AbstractThis work deals with the optimal choice of biomass-to-ethanol path by using SWOT analysis... more AbstractThis work deals with the optimal choice of biomass-to-ethanol path by using SWOT analysis, where Opportunities and Threats are including within a complete set of forecasting scenarios about the environmental change. The methodology developed is presented herein under the form of an algorithmic procedure with 24 activity stages and 6 decision nodes. A Delphi method properly modified to provide estimated scores in fuzzy form (to count for uncertainty) is also used. An implementation of this procedure for a district in Central Greece showed that the sugarbeet-to-ethanol path dominates over the alternatives of using corn and wheat as energy crops. Sensitivity analysis round the optimal choice proved that this is a robust solution.
Archives of Business Research, Dec 12, 2021
 Data analytics is one of the biggest "revolutions" that have taken place in recent yea... more  Data analytics is one of the biggest "revolutions" that have taken place in recent years at the business level, enabling many companies to go through a digital transformation, reducing risks and costs and making them more Agile and Lean. Data analytics is a process with heavy business relevance, companies are analyzing data - numbers mainly - and trying to determine decisions for the future based on it. Hence, severe pressure is being posed on public companies to dwindle their operational costs. A method contributing to this direction is the Lean philosophy, as through proper strategies, with its practices and tools leads to substantial resources saving. Each company possesses a unique way of integrating the principles and practices of Lean Management. In other words, there is no specific methodology, which is applicable by every business worldwide. Explicit condition for the success of Lean Management is the presence of the Effective Change Management. Data analysis is achieved by using the quantitative research method, which highlights the existence of influence as a "moderator effect" of the strategy followed by an effective change management compared to the aforementioned critical success factors (CSFs) was examined by performing interaction analysis in "IBM SPSS Amos 21, so that the parsimonious transformation is feasible. The quantitative approach is based on sample research with standardized questionnaire actualized at the two biggest Greek companies of public interest and utility purpose. The data from the participants’ responses ere inserted on a data basis «SPSS Version 23 for Windows». The findings of the research showed that human and organizational factors determine the greatest part of the effective integration of the Lean Management in public companies. The study examined, the influence of an Effective Change Management on important CSFs for a successful integration Lean Management (Lean Transformation) in Greek public companies. Also contributes to fill a research gap on the impact of Lean Management in public companies, since the vast majority of research work is focused on the private sector.
Acta horticulturae, Mar 1, 2015
One of the basic requirements for sustainability is to focus upon the entire lifecycle of the pro... more One of the basic requirements for sustainability is to focus upon the entire lifecycle of the product. In the agri-food sector, companies which achieve climate neutral agri-food products are distinguished by climate-neutral labels, in recognition of their social responsibility and contribution to environment protection. Valid CO 2 certificates which minimize climate-impacting emissions include the right to achieve net zero carbon emissions by offsetting or buying enough carbon credits to achieve carbon neutral, or having a net zero carbon footprint. Furthermore, value adding can be achieved in the customer-driven value creation chains, as more and more consumers are becoming aware of the company's contribution in environmental protection. In this respect, the aim of this study is to shed light in the specific attributes and perspectives of such practices and to explore how they can transform the challenge of climate change to opportunity for environment protection and sustainability. The paper highlights the need for successfully implemented climate neutral products and services, involving collaborative innovations which may also result in total cost reduction and product quality upgrading, particularly if incorporated in Sustainable or Green Supply Chain Management (GSCM). Moreover, social and company benefits can accrue especially for agri-food products which have already labels like protected designation of origin (PDO), protected geographical indication (PGI) and traditional specialty guaranteed (TSG). This paper also includes a survey conducted with consumers for assessing their behavioral patterns with regard to such issues. Finally, the major contribution of this study is the development of a conceptual model that presents the necessary managerial steps towards the production of green and climate neutral products.
International Journal of Information Management, Dec 1, 2003
Information technology (IT) has transformed business practices in the last several decades: opera... more Information technology (IT) has transformed business practices in the last several decades: operations, product strategies, distribution, and customer service have become increasingly dependent on IT. Moreover, IT has changed its orientation from that of pure operational utility in the 1960s and 1970s to that of a competitive weapon in the 1990s and today. These phenomena have affected the way modern organizations are managed, as well as the way IT affects the strategic activities of an organization's value-chain. In particular, aligning an organization's business and IT strategies in order to deliver higher business performance presupposes a strategic business opportunity to which information systems technology is integral. In other words, Strategic Alignment between business and IT can have a positive business impact only if we see an organization's IT components as parts of a well-integrated organizational system. If business strategy is viewed separately from IT strategy or IT strategy is viewed only as a ''support'' tool, then there is little likelihood that the above positive impact of strategic alignment can take place. This research suggests, develops and tests a strategic co-alignment model by examining three types of integration that impact the planning process and the overall performance of information-intensive organizations: technological integration (TI), functional integration and strategic integration (SI). The results of this research yield some useful set of guidelines for theory building for IS, as well as for the business practice aspect of IS: most interesting is the role of consistency (co-alignment) between an organization's business and strategic information systems plans to improve overall firm performance. Other recommendations include having a high degree of involvement of IS executives in corporate planning, the use of outsourcing services to promote organizational systems integration, and the importance of internal coordination mechanisms to facilitate both systems consistency and lower transaction costs. Finally, this study has employed cluster analysis and discriminant analysis to interpret the research findings.
SPOUDAI Journal of Economics and Business, Dec 19, 2019
Our modern society and economy is moving toward a knowledge-based and serviceoriented global worl... more Our modern society and economy is moving toward a knowledge-based and serviceoriented global world. With the increase of mobile network, mobile devices, and internet of things, many industries, including government departments, private firms, and research communities, offer more transparency through releasing data. Data are considered a fundamental prerequisite to gain knowledge and produce services. Hence, there is the argument that data should not be captive but set free and while, there is a proliferation of data and IoT, there is still need for studies that examine open data, assess the current status of research, and propose future directions. Here, we conduct a review of literature to the current state of research on open data and how can we apply lean management for public industries in Greece.
MPRA Paper, Jun 1, 2017
This research paper deals with the investigation, whether from the results of the implementation ... more This research paper deals with the investigation, whether from the results of the implementation of the ABC costing method to a public company, a suitable KPI framework can be created so that it functions as a useful tool which will contribute to the company"s transition to a lean function. The subject of accurate measurement cost for the transition of a traditional Public Company to a lean Company has received little attention within management costing, since little empirical research has been performed on this subject. It seems that the reluctance to change an entrenched traditional costing system is fed by a lack of empirical evidence of the value the change may bring (Fullerton and Kennedy 2009). The aim of the study is thus to contribute to the overall knowledge on Lean thinking. 1.3 Research Questions This paper attempts to answer to the research question concerning the ability to create a framework of KPIs that is based on the results of the implementation of the ABC costing method and to function as a useful lean tool supporting the attempt of transforming a transitional public company to a lean public company. Specifically, it investigates the question whether in these indicators can be included indicators that concern the cost of the activities, the productivity and the responsiveness, as these originate after implementing the ABC costing system to a public company.
MPRA Paper, Apr 29, 2017
This research highlights the malfunctions and the inaccurate information of the conventional cost... more This research highlights the malfunctions and the inaccurate information of the conventional cost methods that are used nowadays in most Greek public companies. It poses as a research topic the resolution of the above mentioned problem with the development of a reliable and accurately informative cost system based on the ABC method, which will offer support to those companies concerning the amelioration of their total performance and function. This paper also shows the ability of the ABC costing method as a tool which contributes to the transition from a traditional public corporation to a lean corporation after the fulfillment of three fundamental points. First prevents distortions of the cost of activities of a company with the provision of exact measure of the cost of those activities then defines the non value added activities so it limits the wastefulness in a corporation and final introduces the mentality of lean thinking to the employees of the corporation, since each employee knows the flow of the action he performs, its cost and value. This paper includes a contrast on a theoretical basis of the traditional cost systems and the ABC method, presents an application of ABC and a case study of applying ABC to a Greek Public Company investigating its use as a lean tool that helps the saving of resources and the transition to a lean production model.
His current research interests include Semantic Web, Knowledge Management, Virtual Laboratories a... more His current research interests include Semantic Web, Knowledge Management, Virtual Laboratories and e-Learning setups for business training and Business Intelligence.
Series on resource management, Dec 13, 2001
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Papers by Yannis Pollalis