• Nikolaos (Nikos) Cheimarios.

Education.


Honors and awards

Research.


From a broad perspective, my research combines different models from multiple scales (PDEs, ballistic, MC/kMC, MD, ab initio) in an effort to understand how the physical/chemical phenomena - including their non-linear character - in engineering processes affect materials properties. Another pilar of my research is scientific software development in combination with high performance computing (HPC) in CPU/GPU and more recently in Quantum computers.

Multiscale modeling in CVD processes.

My research focuses on combining models from different scales in order to efficiently study, control and propose advantageous operating windows of the CVD process of concern. I combine macro-scale models, i.e. models based on partial differential equations (transport phenomena - continuum regime) with ballistic transport and Kinetic Monte Carlo models, in the micro- and nano- scales respectively. For a brief outline of our work please check pages 5-9 of ECCOMAS Newsletter .

Non-linear (systemic) analysis.

I combine different computational methods, such as Recursive Projection Method (RPM) and arc-length continuation in order to enable commercial software to perform certain non-linear analysis tasks. The computational tools developed are independent of the underlying physical/chemical system. I have used them to efficiently study non-linear phenomena in CVD processes; from buoyancy induced phenomena to symmetry breaking and periodic (in time) flows. This work was partially funded by OSRAM Opto semiconductors during my post doc years.

Polymer properties via Monte Carlo methods.

Polymer properties are hard to compute with conventional molecular methods (such as molecular dynamics) especially when the architecture of the polymer chains is complex or the size of the system is too big. In these cases the relaxation times are too large, so the simulations become too expensive or even impossible. In the R&D department of Scienomics SARL, I have designed and developed Chameleon. Chameleon implements the so-called connectivity altering Monte Carlo moves which can efficiently used for computing the properties of large, realistic, complex polymer systems. During my years in Scienomics, Ι have also conducted research for the materials properties of electronic materials via MD and ab initio methods.

High performance (HPC) computing.

Speed does count! For that, I use HPC tools and methodologies - both CPU (MPI, pThreads) and GPU (CUDA, openCL) based - during software development to exploit modern HPC capabilities and to efficiently accelerate my computations. From a more practical aspect, I have designed and currently co-administrate Andromeda, a hybrid CPU/GPU cluster. Recently, I started working on the design and implementation of algorithms in Quantum computers with empahsis on non-linear solvers.

Scientific software development.

Besides Chameleon, I have designed and currently developing Apothesis, an open source software based on the kinetic Monte Carlo method. Apothesis is designed for the analysis of surface phenomena encounter in growth and catalytic processes. It is still in development and only the core of the software is uploaded in github. I develop in C++, Java and python. For user interfaces (UI) I use Qt and zk framework.

Publications.


As my PhD advisor (who - as he told me - was told by his PhD advisor) says: "if it is not published, it is not science".

In journals.

I have authored and co-authored 27 journal publications [h-index=13 (google scholar)]. I put only my two last publications here. For the rest you are welcome to check my Google scholar.

  1. N. Cheimarios “Mean field approximation of a surface-reaction growth model with dissociation”, Physics Letters A 524, 129828 (2024).https://doi.org/10.1016/j.physleta.2024.129828
  2. N. Cheimarios “Surface diffusion effects on the system and the film properties of a Ziff–Gulari–Barshad type growth model", Materials Today Communications 39, 109189 (2024). https://doi.org/10.1016/j.mtcomm.2024.109189

In books.

  1. N. Cheimarios, S. Harrison, A.C.O. Jensen, P. Karatzas, A. Tsoumanis, P. Doganis, P. Tsiros, D.A. Winkler, S. Lofts, K.A.O Jensen, H. Sarimveis, A. Afantitis, I. Lynch, G. Melagraki, NanoSolveIT integration of tools for assessment of human and environmental exposure to nanomaterials. In “Handbook of Functionalized Nanomaterials: Environmental Health and Safety”, Chapter FOUR, pp. 81-120, Chaudhery & Vineet, Eds., Elsevier, 2021.
  2. N. Cheimarios, S. Garnelis, G. Kokkoris, A. G. Boudouvis, “Multiscale modeling of chemical vapor deposition of silicon.” In “Computer Aided Chemical Engineering”, Vol.29, pp. 131-135, E.N. Pistikopoulos et al., Eds., Elsevier, 2011.
  3. N. Cheimarios, G. Kokkoris and A.G. Boudouvis “Multiscale modeling in chemical vapor deposition processes.” In “Honorary Volume dedicated to the memory of Professor N. Spyrellis”, pp. 87-95, M. Loizidou et al., Eds., NTUA, Athens, Greece, 2009 (in Greek).

In conference proceedings.

I have 13 publications in conference proceedings and 28 presentations. I have detailed them in my CV.

Other publications.

  1. E.I. Ioannidis, N. Cheimarios, A.N. Spyropoulos, A.G. Boudouvis, ”On the performance of various parallel GMRES implementations on CPU and GPU clusters”, arXiv:1906.04051 (2019) [https://arxiv.org/abs/1906.04051].
  2. G.Kokkoris, N. Cheimarios, A.G. Boudouvis, "Computational Microscope" for chemical engineering processes, PROMITHEAS, NTUA, 2018 (in Greek).
  3. N. Cheimarios, S. Garnelis, G.Kokkoris and A.G. Boudouvis “ A computational framework for multiscale analysis of chemical vapor deposition processes”. ECCOMAS Newsletter, pp. 5-9, November 2011.

Teaching.


I have assisted in the teaching of Transport phenomena I (Fluid dynamics), Computer programming (Matlab, Fortran), Technical drawing with AUTOCAD in NTUA, School of Chemical Engineering from 2008 to 2012. I have co-taught the course Process and device simulation in the Interdepartmental Program for Graduate Studies in Microelectronics in NCSR “Demokritos” from 2009 to 2012. I have assisted in the undergraduate diploma thesis supervision of 7 undergraduate students (2009-2014), 2 graduate students (2009, 2010), 1 PhD student (2016) and two Erasmus students (2008). Currently I am co-advising one undergraduate students at NTUA and I supervise three students working in Apothesis.

This is me.


Nikolaos (Nikos) Cheimarios

I was born on May, 28th, 1981 in Athens, Greece. I am married to Theodora and we have two wonderful daughters, Efi and Mirto. I love cinema, listening to music, boxing (in Fight Academy), diving and Christmas!

Feel free to contact me.


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E-mails:

nixeimar@chemeng.ntua.gr
cheimarios@novamechanics.com