COMPUTATION OF OPTIMUM WATER COURSE FLOW VELOCITY FOR THE SUSTAINABLE OPERATION OF A FISH REFUGE LATERALLY TO THE FLOW

Στην εργασία πραγματοποιήθηκαν εργαστηριακές μετρήσεις και ανάπτυξη μαθηματικών μοντέλων κυκλοφορίας και μεταφοράς συντηρητικού αιωρήματος για τον υπολογισμό της βέλτιστης ταχύτητας ροής υδατορεύματος για τη βιώσιμη λειτουργία ιχθυοδεξαμενής παράπλευρα της ροής, όπως εμφανίζεται στο ποτάμιο περιβάλλον με τις φυσικές ή τεχνητές δεξαμενές ιχθυοπληθυσμών παράπλευρα στην ροή του κύριου ρεύματος. Τα αποτελέσματα δείχνουν ότι όσον αφορά την παγίδευση αιωρουμένων στην ιχθυοδεξαμενή η καλύτερη περίπτωση (μικρότερη παγίδευση) είναι αυτή στην οποία η ταχύτητα του κυρίου ρεύματος είναι περίπου 0.30 m/s, η οποία βρίσκεται σε συμφωνία με την βέλτιστη ταχύτητα συνθηκών διαβίωσης των ψαριών.In this study the development of mathematical models of hydrodynamic circulation and matter transport and laboratory measurements for the computation of optimum watercourse flow velocity for the sustainable operation of a natural or artificial fish refuge laterally to the main riverine low were held. Concerning the trapping of the suspended particles in the fish reservoir, the results show, that the best case (with the minor trapping) corresponds to flow velocity of the main stream approximately 0.30 m/s, which is in very good agreement with the optimal living conditions of the fishes

In Situ Wireless Channel Visualization Using Augmented Reality and Ray Tracing

This article presents a novel methodology for predicting wireless signal propagation using ray-tracing algorithms, and visualizing signal variations in situ by leveraging Augmented Reality (AR) tools. The proposed system performs a special type of spatial mapping, capable of converting a scanned indoor environment to a vector facet model. A ray-tracing algorithm uses the facet model for wireless signal predictions. Finally, an AR application overlays the signal strength predictions on the physical space in the form of holograms. Although some indoor reconstruction models have already been developed, this paper proposes an image to a facet algorithm for indoor reconstruction and compares its performance with existing AR algorithms, such as spatial understanding that are modified to create the required facet models. In addition, the paper orchestrates AR and ray-tracing techniques to provide an in situ network visualization interface. It is shown that the accuracy of the derived facet models is acceptable, and the overall signal predictions are not significantly affected by any potential inaccuracies of the indoor reconstruction. With the expected increase of densely deployed indoor 5G networks, it is believed that these types of AR applications for network visualization will play a key role in the successful planning of 5G networks

Modelling of Environmental Parameters of a Harbor Basin in a Coastal Zone with a Seawall

Long straight seawalls along the coastal front are quite common, especially in cases of coastal cities. In this study in the middle of a coastal zone, a harbor basin in the form of an orthogonal area recessed to the waterfront is considered. A mole of variable length and position offers protection from waves. The renewal time of the waters and the self-purification capacity of the harbor under the influence of alongshore coastal currents of different intensity were examined. The effect of technical partial closing of the harbor’s entrance to the water renewal rate is examined in the present research. More specifically, the study was based on the use of a two dimensional, depth averaged hydrodynamic model which describes the water circulation along the coastal zone. For the solution of the equations of mass and momentum conservation, the method of finite differences was used. The adjustment and the validation of the reliability of the numerical model at a laboratory level were conducted in a recent research based on the use of PIV measurements which ensured a very good agreement between numerical and experimental results

A Holistic Virtual Laboratory on Wireless Communications and Sensor Networks

Virtual laboratories have evolved into an adequately mature educational tool for multiple fields of study. Their use is especially beneficial to modern topics such as modern wireless communications. Related solutions in this field explored various approaches and architectures in designing such a virtual environment. The presented software package combines these fragmentary conclusions to a holistic and extensible laboratory architecture. Classic and modern topics, such as propagation, green networking, indoor communications and sensor networks are discussed through interactive 2D/3D environments. The student is also introduced to field measurement procedures and ray tracing principles. Statistical assessment in the context of a postgraduate course in wireless communications demonstrates the educational benefits of the approach