Technological Educational Institute of Western Macedonia

About: Technological Educational Institute of Western Macedonia is a based out in . It is known for research contribution in the topics: Symplectic geometry & Numerical integration. The organization has 291 authors who have published 522 publications receiving 7682 citations. The organization is also known as: TEI of West Macedonia & TEI of Western Macedonia.

Designing interconnected haptic interfaces and actuators for teleoperations in mobile ad hoc networks

Abstract: The growing acceptance of wireless ad hoc networks in war situations, emergency situations, research applications, and conference rooms has resulted in the massive growth of these networks. Interconnecting haptic interfaces in virtual environments is rather a demanding task. This paper presents the topology of the mobile ad hoc networks. Moreover, it outlines the thresholds, the limitations, and the techniques for using haptic interfaces for teleoperations in a mobile ad hoc network. Routing algorithms and congestion control techniques for using haptic interfaces in mobile ad hoc networks are analysed. Simulations are taken place in order to test whether an ad hoc network can support the interconnection of haptic interfaces. Resulting this, we could say that on-demand protocols, such as DSDV, are suitable for networks with a large number of nodes and frequent modifications of network topology.

Mitigation of negative impacts of distributed generation on LV distribution networks through microgrid management systems

Abstract: Renewable based distributed generation (DG) particularly in low voltage (LV) distribution networks may cause voltage limit violations, line overloads and increase in network losses. Siting and sizing of DG penetrations are generally done according to the worst case scenarios. However, since these cases occur rarely in long term operation, a realistic design enables more DG penetration. There are numerous conventional methods, each having several benefits and drawbacks. Local energy management systems can also be part of the solution. This study investigates the negative steady state operational impacts of DG on LV distribution networks and proposes a microgrid management approach to mitigate those impacts. A field data-based virtual test bed is used to simulate undervoltage and overvoltage issues and a microgrid energy management approach is developed and tested to minimize the negative impacts on the network. Moreover, Digital Audio Broadcasting (DAB) as data transmission means in microgrids, is discussed as an adaptable communication solution for its real-world implementation.

Effects of the Greek Financial Crisis to the Food Manufacturing Firms

Abstract: The objective of this study is to draw conclusions about changes over the crisis period in firm performance, using accounting data for 331 food and beverage manufacturing firms in the period from 2005 until 2016. The present study aims to advance our knowledge in three distinct ways: first none of the studies investigated what happened after 2012, second, we split our data in three groups: before crisis (2005–2008), first period of crisis (2009–2012) and second period of crisis (2013–2016), and third taking into account that the implementation of the strict austerity program for Greece in 2010 caused a substantial decrease in demand for goods and services pushing the Greek firms to a deeper recession, we examine differences between the years before 2011 (2005–2010) where the real crisis for Greece started with the implementation of austerity measures, and after 2011 (2011–2016). Fixed effects results suggest that, during economic crisis the efficient and older firms are most profitable, indicating that older firms have the ability, the structure and the experience to achieve a higher profitability. Leverage is negatively related to profitability, which shows that large interest rates due to economic crisis associated with high debt levels result to lower profits while the results provide evidence for a non linear relationship between market share and profitability.

Application of inverse dispersion modelling for the determination of PM emission factors from fugitive dust sources in open-pit lignite mines

Abstract: The operation of large open-pit lignite mines represents a significant source of fugitive dust emissions connected to energy production. Emission inventories can be used to provide operational estimates of the total dust burden in the surrounding areas attributable to mining operations. In this work, a methodology based on the inverse dispersion modelling approach, combining two different dispersion models, is used for preparing a dust emissions inventory for several activity types in the lignite mines of Western Macedonia, Greece. A three-year campaign of field measurement experiments provides the necessary meteorological data and upwind-downwind concentration levels in the area of each activity. A comparison of calculated emission rates provided by the two dispersion models indicates a very good agreement, while the normalised downwind concentration timeseries are accurately reproduced. Emission factors are calculated for each experiment and per-activity, leading to the formulation of empirical relations for the total fugitive dust emissions.

Middleware IoT protocols performance evaluation for carrying out clustered data

Abstract: Several IoT middleware protocols have been proposed for the wireless transfer of IoT data. The main representatives are the CoAP, the SOAP, the MQTT and the HTTP protocols. The main concerns on these technologies are the delay, packet loss, processing effort and power consumption that IoT devices demand, in order to successfully transfer wireless data to the cloud. In exchange for the reduction of the power consumption, many of these technologies try to lower the data throughput, minimize security, or even reduce the distance range of device coverage. In this paper authors compare the performance of IoT application protocols, based on M2M delay and the extra payload that they enforce to the transmitted data. Experimentation tests reveal which protocol is best suited for different network and application scenarios accordingly.