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Prioritizing of volatility models: a computational analysis using data envelopment analysis
No full textEconomic crisis and uncertainty in global status quo affect stock markets around the world. This fact imposesimprovement in the development of volatility models. However, the comparison among volatility models cannot be made based on a single-error measure as a model can perform better in one-error measure and worstin another. In this paper, we propose a two-stage approach for prioritizing volatility models, where in the firststage we develop a novel slack-based data envelopment analysis to rank volatility models. The robustnessof the proposed approach has also been investigated using cluster analysis. In the second-stage analysis, it isinvestigated whether the efficiency scores depend on model characteristics. These attributes concern the timeneeded in order to estimate the model, the value of Akaike Information Criterion, the number of models’significant parameters, groups and bias terms, and the error sum of squares (ESS). Further, dummy variables have been introduced to the regression model in order to find whether the employed model includesan in-mean effect, whether the assumed distribution is skewed, and whether the employed model belongs tothe generalized autoregressive conditional heteroskedasticity (GARCH) family. The main findings of this research show that the number of models’ statistically significant coefficients, ESS, and in-mean effects tend toincrease the efficiency scores, while time elapsed, the number of statistically significant bias terms, and skewederror distributions tend to decrease the efficiency score.3052302233
Selfishness in Mobile Ad-Hoc Networks: A Literature Review on Detection Techniques and Prevention Mechanisms
No full textConstant connectivity is one of the most challenging requirements modern communicationnetworks promise to satisfy. 5G and Beyond applications and the proliferation of Internet of Things (IoT)applications make mobile networks one of the most discussed research topics of the present, while researchis already moving towards the design specifications and development of 6G services and solutions. Usingmulti-hop patterns, mobile nodes can move around always maintaining their connectivity in a pervasiveand ubiquitous manner. New possibilities emerge from this progress, whereas long known challenges stillexist and evolve. One of them is the selfishness or unwillingness of some nodes to spend resources to servethe communication requests of other nodes, not in a malicious but rather in a self-conservative manner.While intentional misbehavior of nodes is considered a security issue, selfishness is studied separately inthe relevant literature and has attracted a lot of research attention. In this review we attempt to present theleading research on the detection techniques and the preventive mechanisms employed by previous studiesto address the selfishness problem in mobile ad hoc networks, and to identify the trends during the pastfew years, focusing primarily on the routing layer. We follow a systematic methodology to identify, select,categorize, and analyze the relevant research and we use a concept-centric approach to present the resultsforming a comprehensive starting point for future research.11868958690
Understanding BMI from Industry 4.0, knowledge management and market uncertainty perspective
No full textPurpose: The main purpose of this study is to investigate the role of Industry 4.0 capability (I4.0 C) in creating a supportive environment for business model innovation by focussing on the mediating role of knowledge management capability (KMC) and the moderating effect of market uncertainty. Design/methodology/approach: This paper uses interviews with managers and academics. Data were collected from 379 managers; CFA and finally regression analysis were performed, and the program “PROCESS” software was used to validate the data and examine the hypothesized relationships. Findings: KMC mediates the relationship between Industry 4.0 capability and business model innovation. The effect of Industry 4.0 capability on KMC is stronger for firms with increased market uncertainty. In contrast, the impact of KMC on business model innovation is weaker for firms operating in highly-uncertain markets. Research limitations/implications: Data were collected at only one point in time from one country, Greece. This might pose limitations on the generalizability of our results. Future research should test the relationships examined in this study in other international contexts. Practical implications: Managers should invest in more advanced technology in order to obtain knowledge and capability. In addition, they need to pay more attention to how their firms' knowledge derived from Industry 4.0 contributes to business model innovation. Originality/value: The current state of knowledge of both theory and practise for critical organizational factors such as Industry 4.0 capability, KMC, business model innovation and market uncertainty will be extended.2951522154
How cash-back strategy affect sale rate under refund and customers’ credit
No full textThis paper attempts to develop a dynamic model for a chain, including online shops and customers. In this chain, online shops can sell their goods directly and through a cash-back website. Cash-back market enables customers to receive part of a paid amount in cash or as a credit after the purchase by creating a link. The effects of this website and credit assignment are not clear to us yet, but cash-back helps those sensitive about the price and those who think markets are overselling to tend to shop more. Besides, we will investigate the refund-motivating policy in this paper, which enables customers to return the merchandise in case of dissatisfaction and receive the whole or part of the money they have paid. This paper's primary purpose is to focus on the effect of credit and motivating policies explained above on the online market's benefit. In this study, we are going to consider motivational policies, in both centralized and decentralized frameworks. Also, choosing a centralized and decentralized method by an online shop is often influenced by societal variables, as shown in this paper. The results suggest that cash-back results in more profit for the retailer; moreover, customer credit leads to more customer loyalty; however, cash-back websites might even result in loss of customers' trust in case of unwise use. On top of that, refund strategy works as a back-up for customers, so if the return rate of the market gets calculated wisely, carrying out this strategy might lead to gaining more customers as well.231
Digital Service Platform and Innovation in Healthcare: Measuring Users’ Satisfaction and Implications
No full textWhen it comes to scheduling health consultations, e-appointment systems are helpful for patients. Non-attendance is a common obstacle that many medical practitioners must endure when it comes to the management of appointments in healthcare facilities and outpatient health settings. Prior surveys have found that many users are open to use such mechanisms and that patients would be likely to schedule an online appointment with their doctor if such a system was made accessible. Few studies have sought to determine how well e-appointment systems work, how well they are received by their users, and whether or not they increase the number of appointments booked. The purpose of this research was to collect information that would help executives of a state hospital in Thessaloniki, Greece, to improve their electronic appointment system by measuring the level of satisfaction their patients have with it. The results show that the level of service provided by the electronic appointment system is not satisfactory. The quality of the website is another significant factor that does not contribute to the level of satisfaction experienced by patients.12366
On the identification of the oil-stock market relationship
No full textThe alternative identification techniques for oil market shocks could be responsible for the mixed results in the oil-stock market literature. This study employs a Bayesian Structural Vector Autoregression (SVAR) to compare the implications of traditional identification approaches (SVAR with zero/sign restrictions) with those from the baseline model (Bayesian SVAR) for the case of the US. We find that the baseline model implies more plausible posterior price elasticities of oil supply and demand and a more profound effect of oil supply shocks on oil prices. Nonetheless, all models provide qualitatively similar conclusions for the effects of oil market shocks on the US stock market, with shocks coming from the demand side playing a more important role than oil supply shocks. Overall, this study reveals that traditional identification schemes remain a good approximation in practice for the oil-stock market relationship.12010615
Joint QoS Aware Admission Control and Power Allocation in NOMA Downlink Networks
No full textIn this work, we talk about the problem of joint power allocation and user association based on quality-of-service for non-orthogonal multiple access (NOMA) to downlink networks. The problem is especially difficult due to its non-convex form and the large number of optimization variables, which are solved using two different nature-inspired algorithms with low complexity. We investigate the effect of different network parameters on increasing users. Numerical results show that, for a growing number of users, the problem is becoming increasingly difficult, which indicates the increasing network resources required to solve it. The results of the simulations show that using evolutionary algorithms is a fast and effective way to solve this kind of problem. Moreover, the NOMA advantage over OMA becomes clear as the number of users increases. Evolutionary techniques outperform randomly generated solutions, as expected.11308733088
Can Greece Count on its Crisis Emerging Diaspora? Tendencies of the Crisis Emerging Diaspora towards Greece and the Way Forward.
No full textThe research project was supported by the Hellenic Foundation for Research and Innovation (H.F.R.I.) under the “1st Call for H.F.R.I. Research Projects to support Faculty Members & Researchers and the Procurement of High-and the procurement of high-cost research equipment grant” (Project Name and Number: Crisis’ Emerging Diaspora's Tendencies Towards Greece- CR.E.DI.T.T.GR, HFRI-FM17-3816).Since the beginning of the economic crisis, Greece has experienced a new emigration wave that has sparked heated public debates and growing academic interest. Debates have focused on the implication of austerity policies and the ‘brain drain’ phenomenon. This paper goes beyond the brain drain debates. Our knowledge and understanding of the emerging diaspora’s relationship with Greece and their beliefs about the country remain limited. Based on prior research in the areas of Migration Studies and International Relations we explore the current state of the relationship between Greece and its crisis-emerging diaspora. Our research has a twofold aim: to enhance our understanding of the emerging Greek diaspora and to provide practical insights for policymaking. By synthesizing academic literature from international relations and migration studies with empirical analysis drawn from our survey data, we establish a robust framework for comprehending the evolving dynamics of this emergent diaspora. Through this approach, our study not only enriches the scholarly debate but also furnishes tangible, evidence-based policy recommendations designed to harness the diaspora's potential for Greece's socio-economic advancement
Virtualization Technology Blending for resource-efficient edge clouds
No full textEdge computing brings virtualized services closer to users to improve their operation (e.g., in terms of communication latency, reliability, or data privacy) and is considered as a main technological enabler for 5G and beyond ecosystems. Edge cloud orchestration approaches are typically adapting server and network resources to rapid changes in the workload, mitigate resource exhaustion, or address service performance requirements. In this context, we introduce and investigate a new cloud orchestration strategy, called Virtualization Technology Blending (VTB). VTB considers edge clouds supporting alternative virtualization options, including multiple unikernel flavors and container builds of the same or a similar service, which can be effectively blended to handle cases with challenging resource requirements, since they exhibit diverse resource requirements and performance capabilities. Here, we provide an elaboration of VTB, backed by a relevant optimization framework, in order to validate its feasibility and assess its benefits. According to our results, the proposed strategy augments the number of users that can be served up to 74% and improves the server and network resource utilization up to 50.9% and 34.4%, respectively.22510964
The role of Green Public Procurements in energy transition: the case of Western Macedonia
No full textThis paper aims to assess the level of implementation of Green Public Procurements (GPP) in the Region of Western Macedonia—Greece, which is currently under energy transition from lignite to a RES-based energy model. By that assessment, a linkage between the GPP framework and energy transition is created, revealing the distinct GPP criteria that should be adopted by energy-transition regions, which have the potential to strengthen the transition process. Rather than implementing the total number of the GPP criteria, literature and methodology findings indicated that specific GPP criteria are directly connected to energy transition and should be primarily adopted by policymakers in comparison to the rest. These criteria are Electricity, Road Transport, Waste Water Infrastructure and Road Lighting and Traffic Signals. By assessing a sample of 31 procurement officials and scientific experts in the five major municipalities of the region, the implementation level of GPP criteria was measured average-to-low, implying that there is a considerable scope by the region’s main municipal authorities to adopt them to a greater extent. Statistical correlations using Spearman’s rank correlation analysis between specific GPP criteria were also identified, indicating distinct interconnections between the criteria pairs that imply commonalities in the implementation framework of GPP. The paper’s implications for future research led to the identification of specific GPP criteria in the public procurement process, that have the potential to enhance green sustainability and boost energy transition.128