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ntheofan/README.md

Hi, I'm Theofanis Nikolaou 👋

Applied AI & Data Professional | Python · SQL · Machine Learning · RAG


👨‍💻 About Me

I'm an Applied AI & Data Professional with an MSc in Artificial Intelligence and Applications and 10+ years of experience across financial operations, payroll systems, analytics, automation, and data-intensive environments.

I currently serve as an Information Technology Officer (Captain), Joint IT Corps, Hellenic Armed Forces, working with large-scale payroll and HR data supporting 55,000+ personnel.

My current focus is the transition from analytics and academic AI into production-oriented AI and machine learning engineering, with particular interest in:

  • Retrieval-Augmented Generation (RAG)
  • Applied Machine Learning
  • LLM-powered applications
  • Python backend development
  • SQL and data-intensive systems
  • API development and containerization
  • Cloud-based AI deployment

I enjoy working at the intersection of AI, data, software engineering, and real-world business problems — particularly where reliability, traceability, and structured evaluation matter.


🚀 Featured Work

📄 Financial RAG for Corporate Filings

My MSc thesis explored the design and empirical evaluation of Retrieval-Augmented Generation systems for financial-document analysis.

The system was evaluated on real financial filings using multiple retrieval architectures:

  • Dense retrieval with BGE-M3 + FAISS
  • Hybrid retrieval using FAISS + BM25
  • Reciprocal Rank Fusion (RRF)
  • Cross-encoder reranking
  • Query expansion for financial terminology
  • Retrieval and generation evaluation with RAGAS and RAGChecker

The work focused not only on building a RAG pipeline, but on systematically studying retrieval quality, evidence coverage, faithfulness, hallucination, and failure modes.

Tech: Python · BGE-M3 · FAISS · BM25 · RRF · Cross-Encoder Reranking · RAGAS · RAGChecker


📊 Customer Churn Intelligence

An end-to-end machine learning project focused on customer churn prediction and decision support.

The project explores the full ML workflow:

  • Data preprocessing and exploratory analysis
  • Feature engineering
  • Model training and comparison
  • Classification evaluation
  • Explainability and business interpretation
  • Reproducible ML project structure

Tech: Python · pandas · scikit-learn · Machine Learning · Data Visualization


🧠 What I'm Working On

I'm currently strengthening the engineering layer around my AI and ML background:

Applied AI
├── Retrieval-Augmented Generation
├── LLM applications
├── Evaluation & grounding
└── ML systems

Software Engineering
├── Python
├── FastAPI
├── REST APIs
├── Testing
├── Git / GitHub
└── CI/CD

Infrastructure
├── Docker
├── PostgreSQL
├── Vector databases
└── Cloud deployment

🛠️ Tech Stack

AI & Machine Learning

Python scikit-learn TensorFlow

Machine Learning · RAG · Embeddings · Hybrid Retrieval · Reranking · LLM Evaluation

Data

PostgreSQL

SQL · Oracle SQL / PL/SQL · pandas · Power BI · Excel

Engineering

FastAPI Docker Git GitHub

REST APIs · Pytest · CI/CD · Pydantic


🎓 Education

MSc — Artificial Intelligence and Applications University of Thessaly Grade: 9.65 / 10

Thesis: Design and Empirical Evaluation of Retrieval-Augmented Generation Systems for Financial Document Analysis


Diploma — Analysts–Programmers Program (ΣΠΗΥ) Hellenic Army School of Computer Programmers Grade: 96.01 / 100


Bachelor's Degree — Economics Aristotle University of Thessaloniki Grade: 8.02 / 10


📜 Selected Certifications

  • Google Data Analytics Professional Certificate
  • Microsoft Power BI Desktop for Business Intelligence
  • Machine Learning A-Z: AI, Python & R

🔬 Academic AI Work

During my MSc, I also worked on projects covering:

Area Topics
Machine Learning Regression, Decision Trees, SVM, KNN, Naive Bayes, Clustering
Deep Learning MLPs, CNNs, CIFAR-10 / CIFAR-100 classification
Generative AI GAN, DCGAN, cGAN, WGAN-GP
Reinforcement Learning Q-Learning
Robotics A* path planning, EKF localization, waypoint control
Data Mining Apriori, Bayesian Networks

These projects provided the theoretical foundation that I am now extending through more production-oriented AI and ML engineering work.


🎯 Current Direction

I'm particularly interested in opportunities around:

Applied AI Engineering · Machine Learning Engineering · AI Software Engineering · Data & AI Engineering

especially roles involving:

  • LLM / RAG applications
  • ML-powered products
  • Python backend development
  • Search and retrieval
  • AI evaluation
  • Financial or enterprise data

📫 Connect

Athens, Greece 🇬🇷

Pinned Loading

  1. financial-rag-platform financial-rag-platform Public

    Evidence-grounded financial document intelligence with hybrid RAG, FastAPI, pgvector, Streamlit and reproducible retrieval evaluation.

    Python

  2. autonomous-robot-navigation-ekf autonomous-robot-navigation-ekf Public

    Python