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  • Scheduled Invited Lectures +

  • 2022 - 2023 +

     Speaker Dimitrios Razis (CV)
    Post-Doctoral Researcher, Department of Civil Engineering
     Topic Nonlinear Waves in Open Channel Flow: A Dynamical Systems Approach (brochure)
     Date  30/11/2022, 11:15 (video (DIAVLOS, YouTube))
     Abstract Monoclinal Flood Waves, Undular Bores, Roll Waves and Solitons are among the most iconic travelling wavefoms observed in Open Channel Flow. On the other side of the spectrum, the Hydraulic Jump, often encountered in open channels, constitutes a paradigmatic example of a standing waveform. In this lecture we will show how the generalized Saint‒Venant Equations ―governing shallow water flow― reduce to a 2nd order nonlinear Ordinary Differential Equation (ODE) capturing the shape of all standing and travelling waveforms appearing in Open Channel Flow. To analyze the aforementioned 2nd order ODE we adopt a Dynamical Systems approach, i.e. we treat it as a set of two coupled 1st order ODEs. From this perspective, all travelling waveforms manifest themselves as bounded trajectories in the phase space (local slope vs. local flow depth of a wave) of the dynamical system. The Dynamical Systems approach provides an unprecidented, tangible geometrical insight on the structure of the various waveforms in Open Channel Flow.

     Speaker Ioannis Kakaras (CV)
    Professor Emeritus, Department of Forestry, Wood Sciences & Design
     Topic Wood products as building materials (brochure)
     Date  7/12/2022, 11:15 (video (DIAVLOS, YouTube))
     Abstract A brief holistic approach of the application of wood building materials in Greece is presented using the appropriate wood species and wooden products. An examination of the wood building constructions is presented, and material failures are highlighted. Techniques and rules of applications which ensure the quality and long lifespan of the wood building constructions are suggested. The rules for the combined use of wood building materials with other building materials as concrete, metals, aluminum and glass are presented. The basic wood structure failures that must be avoided are presented, as well as methods and techniques for the efficient control of errors that can be handled. Simple techniques and methods are suggested for the initial prevention or in situ conservation of wood building contractions, such as roofs, windows, doors, outdoor constructions exposed to the rain, humidity, extreme temperatures and/or in contact with the water or the ground. The necessity for correct specialization of all the participants that are involved in the design or production of wooden building constructions (civil engineers, architects, wood technologists, technicians, wood product merchants) in Greece is emphasized.

     Speaker Anastasia Angelaki (CV)
    Instructor, Department of Agriculture Crop Production and Rural Environment
     Topic Estimation of hydraulic parameters using laboratory experiments and simulation models (brochure)
     Date  11/1/2023, 11:15 (video (DIAVLOS, YouTube))
     Abstract Series of laboratory experiments and mathematical modeling that led to estimation of crucial hydraulic parameters which play significant role to water motion into different soil types are going to be presented. Firstly, experiments were carried out, in order to obtain the particle size distribution of the porous media, while basic hydraulic parameters were determined, such as saturated hydraulic conductivity, soil moisture at saturation, etc. Subsequently, two circles of experiments were carried out: During the first circle, the incoming water volumes were measured, while at the same time, soil moisture at various depths was recorded via electromagnetic waves (TDR). Cumulative infiltration curves and soil moisture profiles were extracted and comparison of the infiltrated water volumes with the volumes that came out from the integration of the moisture profiles was derived. At the second experimental circle, soil moisture along with soil pore pressure was measured and recorded using a ceramic capsule-pressure transducer system, during drainage and imbibition processes.

    Comparative evaluation of two infiltration models was held using the experimental data, while the effect of the hydraulic parameters on water motion was investigated. Also, the characteristic curves of the 1st drainage, the 2nd imbibition and the 2nd drainage were extracted and the not-injective relationship of soil moisture-pressure was confirmed. Specific software was used to simulate the imbibition process and the hydraulic parameters that affect the shape and form of the characteristic curve were derived. In addition, hydraulic capacity (C), diffusivity (D), unsaturated hydraulic conductivity (K) and sorptivity (S) were also determined using algebraic, numerical and graphical methods. Theoretical research on the mathematical models that were used, along with the correlation of the experimental results with the predictions of the theoretical research was also carried out. Finally, the results of a recent research (2022) will be presented, where the above methods have been extended to soils contaminated with heavy metals, in order to investigate the impact of the presence of the heavy metal cations on hydraulic parameters and water motion.

     Speaker George Mantanis (CV)
    Professor, Department of Forestry, Wood Sciences & Design - Laboratory of Wood Science & Technology
     Topic Traditional and modern techniques for wood protection (brochure)
     Date  15/3/2023, 11:15 (video (DIAVLOS, YouTube))
     Abstract The lecture is related to the traditional and modern techniques used in the protection of wood. In the beginning, fundamentals respecting the wood as a biological material, its main disadvantages, and the main biotic and abiotic factors deteriorating the wood, are discussed. Then, the speaker analyses the biological durability of wood and the subsequent use-classes, in accordance with the European standard EN 350. He attempts to present a review of the wooden structures as used in the past, as well as to analyse the traditional techniques for wood protection and conservation relating to pine tar, natural oils and resins. Also, the method of wood protection through impregnation under high pressure, is described and several technical and non- technical aspects of it are discussed. Finally, the old traditional Japanese protection technique called Yakisugi is shortly presented.

     Speaker Hariklia Tsalapatas (CV)
    Instructor, Department of Electrical and Computer Engineering
     Topic Design Thinking in Engineering Education (brochure)
     Date  3/5/2023, 12:00 (video (DIAVLOS, YouTube))
     Abstract Engineering innovation is a driver of growth and well-being today and in the future. By considering feasibility, desirability, and emerging technology it enables the introduction of solutions to business and societal issues of the 21st century, such as climate change, clean and affordable energy, health for all, quality education, poverty mitigation, responsible management of natural resources, and more to drive future growth. Given that today’s students are the problem solvers of tomorrow, who will be challenged to design responses to emerging challenges, higher education as a sector has a responsibility of building student innovation capacity for turning ideas into action.

    This work presents a gamified design thinking learning intervention for promoting the development of innovation competences among engineering students for introducing solutions to difficult challenges, even if none appears to exist at first glance. Design thinking achieves this through a process of problem-discovery that allows designers to put themselves in the position of users either literally, by immersing themselves in the users’ environment, or through an engagement process that helps them better understand actual, as opposed to perceived, needs. The process allows for the definition of a more accurate problem statement, which in turn may allow the design more effective solutions. Design thinking encourages brainstorming for introducing a broad toolset of potential solutions, from which the design team selects the most viable for developing and evaluating prototypes by further engaging users.

    A digital collaboration service has been developed that encourages students to engage in problem-solving in teams anywhere and anytime. Through the learning service under development students work in jointly owned digital workspaces in which they may share their work on problem discovery and understanding, analysis of user needs, problem definition, and solution design. The proposed service is flexible and encourages students to share and build on each other’s ideas through small notes posted on a common canvas. The educator has broad flexibility in designing exercises for engaging students as well as in highlighting specific steps of the design thinking process. Finally, gamification elements, such as clear goals, feedback, recognition, rewards, and a sense of affiliation, promote student long-term engagement in the learning process.

    The work is implemented in project ICT-INOV: Modernizing ICT Higher Education for Harvesting Innovation that is funded by the Erasmus+ Capacity Building in Higher Education program. It is implemented in Greece, Portugal, Italy, Estonia, Malaysia, Vietnam, Pakistan, and Nepal encouraging the exchange of know-how and experiences towards modernizing higher education practices.

     Speaker Nikolaos Maniotis (CV)
    Post-Doctoral Researcher (AUTH), Academic fellow (UTH)
     Topic Computational study of separation of magnetic nanoparticles from fluids in biomedical and environmental applications (brochure)
     Date  12/5/2023, 14:00 (video (DIAVLOS, YouTube))
     Abstract The process of migration of magnetic nanoparticles and colloids in solution under the influence of magnetic field gradients is an essential step in separation technology used in various biomedical applications. In addition, several environmental applications of magnetic nanoparticles have already been implemented on a large scale, such as wastewater treatment and pollutant removal. In some of these applications, magnetic nanoparticles are added to circulating water to purify it from toxic substances such as hexavalent chromium. The first objective of this lecture is to approach the artificial removal of magnetic nanoparticles from the blood circulation under the influence of an external magnetic field, through a mathematical model corresponding to the model of targeted drug delivery and to determine the conditions under which their separation becomes possible. The second objective is to study the removal of magnetic nanoparticles from drinking water with the further development of a pilot device. This consists of a rotating disc on which rectangular NdFeB permanent magnets are hosted in a Halbach arrangement (Figure). In both cases presented, the study is done computationally in two and three dimensions by numerically solving the differential equations and simulating the trajectories of the particles, for different combinations of values of the parameters that affect the movement, estimating each time the percentage of the particles that are being removed by the magnetic field, with the aim of identifying the optimal conditions for their complete elimination.

  • 2021 - 2022 +

     Speaker Francesco Dal Corso (CV)
    Associate Professor, University of Trento, Italy
     Topic Buckling, restabilization and dynamics of extremely deformable structures subject to configurational forces (brochure)
     Date  1/12/2021, 11:00
     Abstract The concept of configurational (material) force has been introduced by Eshelby to describe the motion of massless (voids, microcracks, vacancies, or dislocations) or heavy (inclusions) defects within a solid body as the result of mechanical or thermal loading. This concept has been exploited through the years for modelling the crack-driving force in fracture mechanics, the Peach–Koehler force of dislocations, or the material force developing on a phase boundary in a solid under loading. In the present work, the action of configurational forces on elastic structures are theoretically and experimentally proven in the presence of a specific movable constraint: a frictionless, perfectly smooth and bilateral sliding sleeve. Intriguing mechanical behaviours are disclosed for compliant structural systems involving configurational constraints. The following cases will be examined: (i) An elastic rod constrained by a frictionless sliding sleeve ending with a linear spring and subject to a dead load at the other end, (ii) The sudden release of a rod with a concentrated weight attached at one end and partially inserted into a frictionless sliding sleeve at the other and (iii) The periodic oscillation of a configurational constraint during the fall of a rod. The results represent innovative concepts in mechanics to be used in advanced applications, as for example in actuation mechanisms, energy harvesting, vibration mitigation, shock absorbers.

     Speaker Vassiliki Kati (CV)
    Professor, University of Ioannina, Head of Biodiversity Conservation lab, Ioannina, Greece
     Topic The nexus roads-windfarms-biodiversity under the light of sustainable spatial planning (brochure)
     Date  22/12/2021, 11:00 (video (DIAVLOS, YouTube))
     Abstract Humanity depends directly on biodiversity and its services but we currently face both a biodiversity and a climate crisis. The lecture will focus on two topical issues: (a) Road sprawl is a key driver behind biodiversity loss. We suggest a new national and European roadless policy towards the non net-land take milestone. We present the roadless map of Greece, and we suggest the conservation in legal terms of large roadless areas as ecosystems of high natural, ecological and aesthetic value. The Greek prime minister announced the conservation of roadless areas in the world summit COP26 under the emblematic title “Untrodden Mountains”. (b) Aeolian energy is the leading renewable energy source. However, we often face the paradox of impacting on biodiversity to combat climate change. We present a novel method of spatial planning that enhances windfarm sustainability: investments are prioritized in the most fragmented zones that lie outside the Natura 2000 network of protected areas. The suggested investment zone supports wind harnessing 1.5 times higher than the 2030 national goal, having only marginally lower (4%) wind speed. The sustainable scenario provides significant benefits to biodiversity and society. It is not known if the sustainable scenario will be integrated in the forthcoming national spatial planning for renewables. More info here and here.

     Speaker Chrysi Laspidou
     Topic The SIM4NEXUS Serious Game (brochure)
     Date  12/1/2022, 11:00 (video (DIAVLOS, YouTube))
     Abstract A Serious Game (, produced by the Eu-funded Horizon 2020 SIM4NEXUS project, will be presented. The Serious game is a computer game that aids learning about the Nexus by helping users to understand and explore the interactions between water, energy, land and food resources management under a climate change context, divides the problem into manageable interventions, and allows participants to learn by doing. It is built upon system dynamics models with a sound scientific basis. The ultimate goal of game development is to create a fun and interactive capacity-building tool to be used in research, educational settings and management. The Serious Game enables players to implement policies in a gameplay environment and explore how policies impact on different Nexus components. Summary information is given about policy actions, assigned costs and potential benefits; this facilitates scorekeeping according to both financial and social capital metrics. Costs are tallied against benefits, which are revealed as gameplay progresses. This allows a player to measure progress and compare to others. The Serious game includes a strategy map that facilitates comparison of policy impacts in different regions, a virtual card table in which policy cards can be applied through a drag-and-drop interface, and a visualization system that shows the impacts of users’ decisions on the model.

    The workshop will be conducted virtually. Interactive audience engagement platforms will be applied seeking the active involvement of the participants.

     Speaker Rania Delidimou
    Civil Engineer, University of Patras / MSc Structural design and Retroffiting, NTUA
    Michalis Themelis
    Architect AUTh / MSc Architectural design, University of Thessaly
     Topic Restoration and reuse of two Pelion Architecture Monuments (brochure)
     Date  23/2/2022, 11:00 (video (DIAVLOS, YouTube))
     Abstract The methodology followed for the study, renovation and reuse of two characteristic stone masonry examples of traditional Pelion Architecture as well as the all around procedures, laboratory checks and Central Monument Council authorisations needed. The assesment, performance under seismic loads and simulations according to the EN8-3 and the latest temporary Greek ΚΑΔΕΤ norm, as well as the N,3028/2002 law framework regarding restoration. The two buildings have three levels in stone masonry, free float stone roofs and partial wooden compound walls on the exterior shell. They were both abandoned for many years and their age is around 150-200 years old. Numerous checks were underheld, in parallel with laboratory checks and simulations in the most adequate software available so as to point the optimum retrofitting materials, quantities and reversible procedures.

     Speaker Valentina Laface (CV)
    Assistant Professor, University of ​​Reggio Calabria, Italy
     Topic The use of storm models in the field of ocean engineering (brochure, presentation)
     Date  9/3/2022, 11:00 (video (DIAVLOS, YouTube))
     Abstract The category of Storm Models approach will be discussed in detail with reference to each of the models belonging to this category. Their application for long-term analysis of ocean storm will be explained and analogies and differences among them will be highlighted. Further, alternative use of this models for ocean engineering application such as energy and downtime estimation as well as extreme wind speed calculation will be presented. These models have the peculiarity to use a simplified storm time history to model the specific problem whatever is the kind of analysis. The simplified storm differs from one model to another and is determined by imposing a kind of equivalence between important storm parameters of actual and equivalent storm.

     Speaker Dr Szymon Cholostiakow (CV)
    Post-Doctoral Researcher, Concrete Technology and Reinforced Concrete Structures Lab
     Topic Use of FRP as internal shear reinforcement of concrete elements (brochure)
     Date  23/3/2022, 11:00 (video (DIAVLOS, YouTube))
     Abstract Owing to the unique mechanical characteristics and lack of plasticity of fiber-reinforced polymers (FRPs), relatively large strains can develop in FRP reinforced concrete (RC) elements at ultimate limit states and this can lead to different relative contributions of concrete and shear reinforcement to the total element's shear capacity. This presentation examines the development and relative contribution of the main shear resisting mechanisms in concrete beams with different overall depths and reinforced with longitudinal and transversal FRP reinforcement. Complementary strain measurements obtained from digital image correlation (DIC) and strain gauges are presented and discussed thoroughly. Although current FRP shear design approaches rely on the assumption that the contributions of concrete and shear reinforcement are constant up to failure, their relative magnitude is found to vary with increasing crack width. The experimental results indicate that, when minimum shear reinforcement is provided, current shear models based on a fixed truss angle approach tend to overestimate the contribution of concrete and underestimate the contribution of shear reinforcement. The use of a variable angle truss model, along with an appropriate reduction in the contribution of concrete, would lead to a more reliable estimate of the main shear resisting mechanisms and optimal design of the required amount of shear reinforcement.

     Speaker George Mantanis (CV)
    Professor, Department of Forestry, Wood Sciences and Design - Laboratory of Wood Science & Technology, University of Thessaly
     Topic Innovative products of wood modification – Uses in outdoor structures (brochure)
     Date  30/3/2022, 11:00 (video (DIAVLOS, YouTube))
     Abstract This lecture is related to state-of-art technologies of thermal and chemical modification of wood, which result in highly innovative wood products with improved physical, mechanical, chemical and biological properties. The lecturer, following a short introduction in wood modification, attempts to display main drawbacks of the natural material, which shall be limited and/or restricted. Then, he shortly presents two of the most prominent products of chemically modified wood, which can be of interest for the new civil engineer and architect, designer, or technologist. Nowadays in Europe, such new modified wood products can be encountered in a variety of outdoor applications. In addition, the chemical processes of acetylation and furfurylation of wood are briefly discussed; useful technical feedback is given from the international bibliography and the Greek practice, in which they have been tested in recent years. At the end, the lecturer presents the method of thermal modification of wood, and a relevant thermally-treated product, which is used mostly in claddings and outdoor decks.

     Speaker Grigorios Tsinidis (CV)
    Assistant Professor
     Topic Underground structures against seismic ground excitation: From seismic behavior and design to seismic vulnerability and resilience assessment (brochure)
     Date  6/4/2022, 11:00 (video (DIAVLOS, YouTube))
     Abstract Underground structure (for instance, tunnels, subway stations, embedded pipelines, etc.) constitute crucial elements of road and rail transportation networks, as well as of energy transmission infrastructure, and are constructed at an increasing rate in seismic prone areas. Considering the vital role of these structures, as well as the significant losses associated with potential seismically induced damage, their adequate seismic design, as well as seismic vulnerability and resilience assessment, are of foremost importance for stakeholders, operators, and governmental bodies. Within this lecture, topics related to the behavior and design of underground structures subjected to ground seismic shaking will be presented, focusing on cases of circular or rectangular tunnels embedded in soft soils. In addition, recent developments in the vulnerability and resilience assessment of underground structures (e.g., tunnels and embedded natural gas pipelines) subjected to ground seismic shaking, will be presented. The above topics will be discussed through the presentation of representative results of advanced numerical analyses and experiments (i.e., tests on model tunnels in geotechnical centrifuges), conducted in the frame of relevant recent research projects.

     Speaker Thanasis Triantafillou (CV)
    Professor, Department of Civil Engineering, University of Patras
     Topic Integrated Structural and Energy Retrofitting of Existing Structures with Advanced Materials (brochure)
     Date  25/5/2022, 11:00 (video (DIAVLOS, YouTube))
     Abstract The scope of the seminar is to present the properties, applications and the great potential of a relatively new generation of composite materials in the field of structural engineering. This new generation of materials comprises inorganic matrices (cementitious or non) reinforced with high-strength textiles (e.g. carbon, glass or basalt fiber textiles), which are either externally bonded on the surfaces of existing structures’ structural elements as a means of enhancing their properties (e.g. strength, ductility), or they are used as internal reinforcement in new structures. Focus will be given on the applications of textile-reinforced mortars in existing reinforced concrete structures when the target is to increase the flexural or the shear capacity of structural elements, or to enhance the local ductility of structural members through confinement. An overview of applications of textile-reinforced mortars in strengthening masonry structures (for in-plane or out-of-plane actions) is also included. Finally, an integrated structural and energy retrofitting system based on the use of textile-reinforced mortars will be presented.

     Speaker Ambrosios-Antonios Savvides (CV)
    Dr. Civil Engineer from National Technical University of Athens (NTUA), Lecturer at Department of Civil Engineering at University of Thessaly
     Topic Open source Finite Element Code for numerical simulations in computational mechanics problems: MSolve. Presentation and capabilities (brochure)
     Date  1/6/2022, 11:00 (video (DIAVLOS, YouTube))
     Abstract The scientific field of Computational Mechanics is one domain of significant importance for Civil Engineers. For all infrastructures like houses, dams, bridges, railways etc the complexity of the load bearing bodies and the loadings subsequent to high quality requirements for the infrastructure. Therefore, the demand for large scale computations is constantly increasing. The evolution and progress of the computer science and software engineering contributes to the satisfaction of this demands. In this lecture an open source Finite Element Code for numerical simulations in computational mechacnis problems is presented. The capabilities and advantages of the aforementioned code will be postulated alongside with fields of improvement which are under investigation and development. Finally, the access to the following code will be provided and a discussion for dissemination purposes will be followed.
  • 2020 - 2021 +

     Speaker Hariklia Tsalapatas
    Instructor, Department of Electrical and Computer Engineering, University of Thessaly
     Topic Problem-based learning in engineering education: experiences in Europe and Asia (brochure)
     Date  21/10/2020, 13:00 (video)
     Abstract Capacity Building in Higher Education project ALIEN: Active Learning in Engineering Education ( aims at promoting active and problem-centred learning as strategic educational approaches in engineering education.

    The advantages of active and problem-centred learning are many. They facilitate the development of fundamental knowledge as well as soft skills, such as analytical and critical thinking, entrepreneurial mindsets, the ability to collaborate in interdisciplinary groups, and much more. They prepare students for their transition from the academic environment to the world of work and build their ability to transfer knowledge to professional environments through non-trivial, open-ended learning scenarios inspired by real-life. And they are in line with the ET2020 targets for modernising education through emerging pedagogical design and digital technology.

    Despite clear educational advantages, active and problem-based learning are not widely implemented. Reasons that inhibit their widespread development include inadequate physical infrastructures, the lack of open educational digital applications and simulations for supporting active learning, and the need to build trainer capacity on integrating digitally enabled, innovative learning design.

    Project ALIEN aims at addressing these challenges by introducing a holistic learning intervention that promotes the broad adoption of active and problem-based learning in Europe and Asia. The project has developed problem-based learning laboratories at 12 universities in Malaysia, Vietnam, Nepal, Pakistan, and Cambodia. It has further developed a digital collaboration platform that acts as a repository of good practices while promoting reuse of educational content towards building value-added learning activities tailored to diverse educational needs. Finally, the project builds the capacity of instructors on deploying active learning through community building events and training that foster the exchange of positive experiences related to problem-based learning in engineering education.

    Webinar participants will have the opportunity to deepen their understanding on the benefits of active and problem-based learning, experience the ALIEN learning intervention, and discuss its impact towards building the problem-solvers of tomorrow.

     Speaker Yannis N. Krestenitis
    Professor, Aristotle University of Thessaloniki
     Topic Sea-level changes & coastal floods. Sort-time forecasts. Climatic changes (brochure)
     Date  4/11/2020, 13:00 (video)
     Abstract The presentation focuses on coastal floods and inundations of coastal zones, as a result of rising sea levels due to the combined action of astronomical tide, meteorological tide and the action of waves. The operational process of short-term prediction of the phenomena of the total rise of the sea level is presented, with the combined use of meteorological and oceanographic mathematical models. The operational forecast concerns the Mediterranean, the Aegean and the Thermaikos Gulf. The aim is to forecast floods in low-lying coastal areas.

    Also presented is the study of the evolution of meteorological tide phenomena (storm surge) for the next hundred years, with the combined use of climate and oceanographic models, considering forecasts (scenarios) of climate change, with reference to the Mediterranean and the Aegean.

     Speaker Haris Stamatopoulos
    Associate Professor, Norwegian University of Science and Technology, Trondheim, Norway
     Topic Timber Buildings: Modeling, Design and Challenges (brochure)
     Date  11/11/2020, 13:00 (video)
     Abstract This lecture presents modeling and design aspects of timber buildings. The most common engineering wood products and timber structural systems are briefly presented. The main ultimate limit state (ULS) and serviceability limit state (SLS) design checks according to Eurocode 5 (EN1995-1-1) and other standards are briefly discussed. Some critical issues with respect to modeling of timber structures are presented with focus on modeling of connections. Then, the lecture presents some of the main challenges of the design of tall timber buildings (wind-induced acceleration and deformation and human-induced vibration of floors at the SLS and seismic design timber buildings). Finally, two research projects at NTNU related to the design of tall timber buildings are briefly presented. The WOODSOL project which aims in the development of multi-storey timber buildings with innovative semi-rigid moment-resisting connections; and the DynaTTB project which aims in the determination of the properties (damping and stiffness) of timber buildings subjected to dynamic loading, by use of component tests and forced vibration of buildings with horizontal shakers.

     Speaker Nikolaos Mellios
    Academic fellow
     Topic Environmental informatics for modelling of freshwater ecosystems: dynamics and impacts of eutrophication and sustainable agricultural water use (brochure)
     Date  18/11/2020, 13:00 (video)
     Abstract The potential of ecological modelling under the frame of environmental informatics to define the factors that affect water quality and quantity parameters on lake ecosystems, will be presented. Karla Reservoir, a Greek hypertrophic constructed lake, suffers from continuous water degradation because of excessive nutrients loading, unaccomplished works, and operational malfunctions. Ecological modelling is conducted to simulate in-lake nutrient dynamics and to reveal the factors affecting its trophic state, while several operational scenarios and a climatic one is applied to estimate the fate of the lake under these hypothetical circumstances. Moreover, cyanotoxins (microcystins) are being modelled through a current artificially intelligence algorithm (ANFIS). Next, cyanobacteria biomass and recreational health risk levels associated to cyanobacterial abundance are modelled on a network of Northern European lakes. Stepwise linear regression, a series of machine learning algorithms and Bayesian hierarchical modelling are applied to test their efficiency in producing reliable results. Lastly, an analysis in terms of which types of crops export the most virtual water through trade, in relation to the benefit in Greek economy, is conducted.

     Speaker Marios Anagnostou
    Academic fellow
     Topic Methods and State-of-the-art technologies on the hydrometeorological extremes observations and forecasting: The flash-flood case of Mandra, Attikis (brochure)
     Date  25/11/2020, 13:00 (video)
     Abstract Severe hydrometeorological hazards such as floods, droughts, and thunderstorms are expected to increase in the future due to climate change. Due to the significant impacts of these phenomena, it is essential to develop new and advanced early warning systems for advance preparation of the population and local authorities (civil protection, government agencies, etc.). In very short time-periods (up to 6 h), small-scale phenomena can be described accurately by adopting a “nowcasting” approach, providing reliable short-term forecasts and warnings. To this end, a novel nowcasting system is presented in this study, combining a data assimilation system (LAPS), a large amount of observed data, including X- band dual-polarization (XPOL) radar precipitation measurements, the Chemical Hydrological Atmospheric Ocean wave System (CHAOS), and the WRF-Hydro model. The system is evaluated on a case study of the catastrophic flash flood event that occurred in the sub-urban area of Mandra in Western Attica, Greece, on 15 November 2017. The update of the simulations with assimilated radar data improved the initial precipitation description and led to an improved simulation of the evolution of the phenomenon. Comparison with flood data from the FloodHub Service showed that the nowcasting system could have provided reliable early warning of the flood event at least 1 hour in advance, giving vital time to the local authorities to mobilize and even prevent fatalities and injuries to the local population.

     Speaker Panos Gourgiotis
    Associate Professor
     Topic Applications of generalized continua to materials with microstructure (brochure)
     Date  2/12/2020, 13:00
     Abstract It is well known that classical continuum theories possess no intrinsic length scale and thus fail to predict the scale effects experimentally observed in problems with geometric lengths comparable to the lengths of the material microstructure. On the other hand, generalized continuum theories intend to capture effects of microstructure by enriching the classical continuum with additional material characteristic length scales, and, thus, extending the range of applicability of the ’continuum’ concept in an effort to bridge the gap between classical continuum theories and atomic-lattice theories. The significance of these theories is that they enrich the classical continuum with additional material characteristic length scales in order to describe the scale effects that emerge from the underlying microstructure. In this way, size effects can be incorporated in the stress analysis in a manner that classical theories cannot afford.

    In this presentation, the theory of couple-stress elasticity will be examined starting from first principles. The theory of couple stress elasticity is the simplest gradient type generalized continuum theory that extends the applicability of the classical theory of elasticity and has been extensively used in the last decade to predict the experimentally observed size effects in many stress concentration problems for microstrucrured materials. Here, we will employ the couple-stress theory to examine crack propagation problems in materials with microstructrure and explain the strengthening effects that are observed in fracture of ceramics. Moreover, we will examine instability problems such as folding and stress channelling that can been explained as a failure of ellipticity in a Cosserat material, in a manner similar to that of the formation of shear bands in a plastic material.

     Speaker Dimitris Kofinas (CV)
    Academic fellow
     Topic Advanced tools for urban water demand simulation and forecasting at multiple spatio-temporal scales (brochure)
     Date  9/12/2020, 13:00 (video)
     Abstract At the current lecture, an investigation on the modeling potential of variable components of the WDNs from the drilling to the tap will be presented. Towards this end, a number of traditional statistical methods will be presented, as well as some AI and hybrid approaches. A number of innovative tools built for specific purposes will also be presented. Among the multiple objectives, on high level, the overall objective is to develop an innovative methodological framework on improving urban water management based on simulation tools that provide detailed overview of the system on multiple scales. The presented investigation is implemented and validated on an actual case study, the WDS of Skiathos Island. This offers some specifications that led to interesting results. Skiathos is a touristic resort with intense touristic influx and intense weather seasonality according to the Mediterranean profile. A series of KPIs has also been applied or introduced and visualised spatio-temporally to reveal hidden cause-effect relations.

     Speaker Georgios Tziatzios (CV)
    PhD candidate
     Topic Assessment and prediction of climate change impact on groundwater resources (brochure)
     Date  16/12/2020, 13:00 (video)
     Abstract This research aims to assess the quantity and evaluate the quality of the Karla basin groundwater system that is under heavy pressure from both extensive exploitation of the available groundwater resources as well as application of agro-chemical products.

    The groundwater status investigation consists of a mathematical simulation of the groundwater flow as well as the transport of nitrates in the lake Karla aquifer using different management scenarios. The Modflow code is used to simulate the subsurface flow and the MT3DMS code for the simulation of groundwater contamination, both codes are part of the Groundwater Modeling System (GMS) suite. Groundwater nitrate pollution is examined at the municipal districts level. The nitrate loading, which varies seasonally, was applied for each type of crop and nitrate leaching was calculated for each crop utilizing the agronomic model GIS-based Environmental Policy Integrated Climate model (GEPIC). Finally, climate change impact on groundwater system is analyzed through SRES scenarios.

     Speaker Konstantinos Papoutsis (CV)
    Logistics Manager - Sustainability, Nike EMEA Operations
     Topic Retail Logistics Costs and Policy Impact: What is the Total Cost to Secure Innovation for a Greener Retail Supply Chain? (brochure)
     Date  3/3/2021, 12:00 (video)
     Abstract Public-policies on freight mobility record tangible cost impacts on supply chains and in logistics processes such as goods handling, transportation, etc. Especially for the retail sector which requires a more responsive performance, the effects are even more critical. Thus, society is impacted by air pollution, noise nuisance, etc. for which they are not accountable, and decision-makers are trying to tackle via new policies. Therefore, sustainability has a cost that should be paid by polluters. On the contrary, retailers seek for innovation to offset the additional operational implications. A holistic approach on pinpointing and estimating the total costs that retailers pay in order to ship their products to customers embedding the policy adoption cost is the main scope of the presentation. A cost model of a retail supply chain is built focusing on urban context and the effects of policies and innovations on total costs and sustainability performance of a retailer’s B2B supply chain are estimated. External costs constitute integral part of sustainability and thus, a sustainability analysis is performed between scenarios, encompassing service and social perspectives.

     Speaker Leonidas Alexandros Kouris (CV)
    Dr Civil Engineer, Joint Research Centre, European Commission
     Topic Seismic and energy upgrading of unreinforced masonry buildings (brochure)
     Date  10/3/2021, 12:00 (video)
     Abstract There is an always more demanding need to upgrade the existing unreinforced masonry (URM) buildings due to their poor seismic performance during earthquakes which has resulted in severe human and economic losses and their low energy performance which significantly increases their energy consumption. The issue of upgrading the URM buildings is of great priority for EE since they are unengineered vernacular structures and far from the levels of the current standards for seismic capacity and energy consumption. Moreover, the latter combined with deterioration due to ageing of materials, environmental degradation, experience of several earthquakes and lack of maintenance, yield to an even higher vulnerability and energy deficiency. Every recent moderate to high seismic shaking caused damage ranging from cracks to partial or total collapse with a high death toll and economic loss. Therefore, innovative techniques integrating advanced materials for the simultaneous seismic and energy retrofitting of the masonry building stock this should be develop. In masonry buildings there are some more requirements for the targets of the retrofitting related to their traditional nature apart from the structural and energy performance; these can be summarised in the reversibility and compatibility of the strengthening materials. Moreover, cost effectiveness remains an important aspect which should be added to them. SPEctRUM, an EU funded by Marie Skłodowska-Curie Actions project hosted in JRC (EC), proposed a hybrid structural-plus-energy retrofitting solution which combines inorganic textile-based composites with thermal insulation systems for masonry building envelopes to meet all the aforementioned requirements. The use of natural material including lime mortars and natural fibers has been investigated and it has been shown that the capacity can be increased substantially. The cost efficiency of the proposed retrofitting system has been explored in a large-scale EU investigation and short payoff times have been found especially in regions of moderate to high seismicity.

     Speaker George Mantanis
    Professor, Department of Forestry, Wood Sciences and Design Laboratory of Wood Science & Technology, University of Thessaly
     Topic Wood and wooden structures (brochure)
     Date  31/3/2021, 12:00 (video (DIAVLOS, YouTube))
     Abstract This lecture is related mainly to wood as a construction material, and to wooden structures. The lecturer, following a short introduction, attempts to cover both the general and specific fundamental principles in regard to this natural lignocellulosic material, which should be well understood by the new engineer – designer – project manager, so as to effectively utilise wood materials in several applications and constructions. The physical, macroscopic, as well as the microscopic characteristics of wood will be analysed. In addition, technical terms respecting the wooden structures will be given in detail, in correlation with the effect of hazard level in constructions, both in wooden and mixed ones. In that respect, the junior engineer will be informed about the natural durability of the most important timber species, and also, the relevant Use-classes will be briefly discussed. All these are directly related with the European standard ΕΝ 350. Further, some technical details of the European standard EN 338 -which is in conjunction with the mechanical properties of woods- will be presented. Last, few of the typical conservation techniques used in wooden structures, will be briefly displayed.

     Speaker Olympia Panagouli
    Associate Professor
     Topic Three-dimensional dynamic response of classical columns consisted of drums connected by dowels (brochure)
     Date  21/4/2021, 12:00 (video (DIAVLOS, YouTube))
     Abstract A numerical investigation on the dynamic response of multi-drum classical columns will be presented. The motivation for this study originates from the need to understand how the 3D dynamic behavior of these columns, surviving in most cases in the form of free-standing columns, is affected by a connection system that was implemented during their construction. For that, the complex dynamic response of multi-drum columns which are part of the colonnade system of the ancient Messene Gymnasium in Greece, is simulated numerically with the finite element code MSC-MARC. In the 3D models, which are based on archaeological information data, special attention is given to the modeling of the iron dowels which were used to connect adjacent drums. The columns are subjected to harmonic ground motions having different acceleration amplitudes and different frequencies. The aim of this parametric study is to investigate the response of the selected columns in both cases, with and without the iron dowels, to understand their role in the overall stability of the column.

     Speaker Ioannis Karmpadakis
    Lecturer, Imperial College London
     Topic Ocean2Coast: Advancements in the statistical representation of waves in the coastal zone (brochure)
     Date  12/5/2021, 12:00 (video (DIAVLOS, YouTube))
     Abstract Hurricanes Rita and Katrina destroyed 113 offshore platforms, 87 of which were in water depths less than 60 m. In this talk, Dr. Karmpadakis will present new physical understanding of the extreme shallow-water waves responsible. This is combined with analyses of an extensive field database and a large set of long, random experimental wave simulations. Key results include an improved description of the largest waves for engineering design and the development of new probabilistic models for extreme waves. In developing these, new light is shed on the competing effects of wave breaking and nonlinear changes. Key aspects of this study have been introduced in the state-of-the-art design of marine and coastal installations, such as offshore wind farms; the reliability assessment of offshore oil and gas platforms; and the improved estimation of coastal flooding.

     Speaker Stavroula Kontoe (CV)
    Reader, Imperial College London
     Topic Pile design for the foundation of offshore wind turbines in challenging ground conditions (brochure)
     Date  26/5/2021, 12:00 (video (DIAVLOS, YouTube))
     Abstract The current worldwide drive towards renewable, low carbon energy has led to rapid expansion in the offshore wind energy sector, moving to deeper waters and larger turbines. The foundations of offshore wind turbines consume a substantial proportion of the capital cost and are designed to sustain axial and lateral loading under both monotonic and cyclic conditions, due to the wind and wave action. Existing design procedures are well developed for common ground conditions, involving sands and clays, but are lacking behind when encountering other challenging geomaterials. Chalk in particular, a weak, carbonate rock with distinctly brittle behaviour, is widespread in Northern Europe, posing severe challenges for the design of driven piles. The presentation will give an overview of advances that have been made in the design of piles driven in chalk, through a series of research projects at Imperial College involving laboratory and field testing as well as numerical analysis.

     Speaker Dr. Maria Tsami
    Post-doctoral Research Associate at the Hellenic Institute of Transport (HIT) - Centre for Research and Technology Hellas (CERTH)
    Head of the Laboratory D1: Intelligent and personalized algorithms for combined transport and tourism services.
     Topic Modeling the impact of transit quality of service on user mode and route choices (brochure)
     Date  2/6/2021, 12:00 (video (DIAVLOS, YouTube))
     Abstract The lecture focuses on the Transit Quality of Service both in terms of evaluating existing services and in terms of planning and predicting the impact of service quality on user’s decisions regarding mode and route choices. Taking into account the perceptions and expectations of both transit passengers and service operators, a) the service quality GAPs are being identified, b) the key quality of service parameters that are of high importance for service users are being analyzed, c) the relationship between users’ satisfaction from the performed quality with their intentions to use the services is examined and finally d) the impact of transit quality of service on user mode and route choices is underlined. Users’ behavior is being modeled by examining a number of quality scenarios, leading to a model that predicts user’s decisions that able to dynamically predict, wherever these quality conditions apply, decisions and transit assignment. This model acts as a reliable tool for predicting transit assignment under given quality conditions but also for managing quality and information to increase the level of satisfaction of existing and potential travelers in order to attract more users in the service.
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