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Scientific machine learning

Scientific machine learning is an emerging field at the intersection of machine learning, scientific computing, and applied mathematics. It leverages domain knowledge from physics, biology, chemistry and engineering to create models that are data-driven and grounded in scientific principles.

Methods such as physics-informed neural networks (PINNs), operator learning and hybrid modeling can help reduce reliance on massive datasets while ensuring predictions that respect fundamental scientific laws. Applications of scientific machine learning span a broad range including reactive flows, pollution dispersion models, materials design, etc.

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Cancer growth modeling

Understanding the underlying mechanisms which lead to the uncontrolled growth of tumors is of critical importance for the application of efficient anti-cancer treatments. In this context a significant number of computational models have been developed. A realistic description of tumor growth requires the modeling of different sub-processes carried out across different scales of space and time.

Cancer growth is the result of cell-level processes during which an individual cell interacts with its micro-environment. To accelerate and thus enable the more efficient study of such models we employ multi-scale methods.

Projective integration is one technique of the computational framework, which wraps around cell-level simulators, and enables the acceleration of computations by carrying out "jumps" in time.

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Population Balance Modeling

Population balance models is a class of problems describing the behavior of particle, crystals, cell, etc populations interacting with each other and their environment. Applications of this modelling approach can be found in a wide region of processes, ranging from aerosols and crystals to isogenic cell populations. Different modelling approaches involve the solution of i) Monte Carlo models and ii) partial integro-differential equations.

Monte Carlo models require substantial computational time and multi-scale techniques can be employed to accelerate simulations and perform systems level analysis. We have successfully applied this multi-scale computational framework in populations of coagulating and sintering solid particles.

Partial integro-differential equations is an alternative modelling approach, which requires the solution of a difficult class of problems. We have demonstrated how this category of problems can be solved within the environment of commercial software packages specializing in solving differential equations (COMSOL Multiphysics (R)) and how this software can be embedded in a computational framework which allows the application of bifurcation and stability analysis. Such an analysis has been applied in cell populations carrying the lac operon gene regulatory network, which encodes the proteins for lactose metabolism.

The application of this computational framework allowed the computation of multiple co-existing population balance solutions, corresponding to different cell phenotypes.

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Computational study of nonlinearities in chemical engineering processes

We study the complex interplay of momentum, heat and mass transfer in chemical reactors giving raise to fascinating non-linear phenomena. A characteristic example is the study of the processes involved in chemical vapor deposition reactors. There, we seek for a product (thin film) with enhanced techonological properties (thickness uniformity).

In a vertical-axisymmetric-stagnation point chemical vapor deposition reactor, 3d computations (exploiting commercial fluid dynamics code) reveal a rich solution space with multiple co-existing steady-state solutions (axisymmetric and non-axisymmetric), as well as periodic solutions.

Our goal is to investigate the critical operating conditions which combine high deposition rate, and film uniformity. In order to do so, the computed flow and temperature field is coupled with chemicaly reacting species that lead to the deposition of thin films.

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Simulation of wetting phenomena on rough solid surfaces

Continuous-level and mesoscopic models (Lattice-Boltzmann) are utilized for the simulation of wetting phenomena on rough solid surfaces. The simulators efficiency is extended so as to perform a systems level analysis, enabling the thorough investigation of wetting on micro-structured surfaces and its dependence on various parameters, e.g. the wettability of solid material and the geometric characteristics of roughness.

Through this investigation, which employs an arsenal of computational tools borrowed from numerical analysis (bifurcation and stability analysis), we can identify parametric regions which allow the co-existence of different wetting states and furthermore we can identify - through eigenvalue analysis -the directions along which a perturbation should be applied for the most efficient wetting state transition.

Funding

  • “TORCH: Investigation of tumor cell heterogeneity impact on drug resistance mechanisms”, Basic Research Program PEVE (NTUA) 2022-2024. (Principal Investigator: M. Kavousanakis, 24 months, 18,000 EUR)

Participation in Research Projects

  • “SABYDOMA: Safety BY Design Of nanoMaterials’’, Horizon 2020, E.C., 2020. (Principal Investigator: H. Sarimveis)
  • “SIMPLIFY: Sonication and Microwave Processing of Material Feedstock’’, Horizon 2020, E.C., 2020. (Principal Investigator: G. Stefanidis)
  • “Molecular simulation and thermodynamics of fluids and advanced technological material’’, NCSR “Demokritos”, 2014-2019. (Principal Investigator: I. Economou)
  • “Roughness design towards reversible non- / full-wetting surfaces: From Fakir Droplets to Liquid Films (HYDROFAKIR)’’, Πρόγραμμα ‘IDEAS’, European Research Council, 2009-2013. (Principal Investigator: Athanasios G. Papathanasiou)
  • "From the cell to the tumour: Effective simulation of macroscopically patterned biological systems with multiscale methods" NTUA, Basic Research Program, 2009-2011. Principal Investigator: A. G. Boudouvis.
  • "Solar cooling of buildings with a continuous operation adsorption cooler" General Secretariat for Research and Technology, Program "ΠENEΔ", 2005-2009. Principal Investigator: J. Palyvos, NTUA.
  • "From single-cell genetic architecture to heterogeneous cell population dynamics" General Secretariat for Research and Technology, Program "ENTEP", 2006-2007. Principal Investigator: A. G. Boudouvis.
  • "From microscopic simulation to coarse, macroscopic behavior: a unified computational framework for problems with multiple space/time scales" NTUA, Basic Research Program "ΠΡΩΤΑΓΟΡΑΣ", 2004-06. Principal Investigator: A. G. Boudouvis.