Generating Synthetic Time-Series Data For Smart-Building Knowledge Graphs Using Generative Adversarial Networks

[This blog post is based on Jesse van Haaster‘s bachelor thesis Artificial Intelligence at VU]

Knowledge Graphs represent data as triples, connecting related data points. This form of representation is widely used for various applications, such as querying information and drawing inferences from data. For fine-tuning such applications, actual KGs are needed. However, in certain domains like medical records or smart home devices, creating large-scale public knowledge graphs is challenging due to privacy concerns. To address this, generating synthetic knowledge graph data that mimics the original while preserving privacy is highly beneficial.

Jesse’s thesis explored the feasibility of generating meaningful synthetic time series data for knowledge graphs. He specifically does this in the smart building / IoT domain, building on our previous work on IoT knowledge graphs, including OfficeGraph.

To this end, two existing generative adversarial networks (GANs), CTGAN and TimeGAN, are evaluated for their ability to produce synthetic data that retains key characteristics of the original OfficeGraph dataset. Jesse compared among other things the differences in distributions of values for key features, such as humidity, temperature and co2 levels, seen below.

Key value distributions for CTGAN-generated data vs original data
Key value distributions for TimeGAN-generated data vs original data

The experiment results indicate that while both models capture some important features, neither is able to replicate all of the original data’s properties. Further research is needed to develop a solution that fully meets the requirements for generating meaningful synthetic knowledge graph data.

More details can be found in Jesse’s thesis (found below) and his Github repository https://github.com/JaManJesse/SyntheticKnowledgeGraphGeneration

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HEDGE-IoT project kickoff

The HorizonEurope project HEDGE-IoT started January 2024. The 3.5 year project will build on existing technology to develop a Holistic Approach towards Empowerment of the DiGitalization of the Energy Ecosystem through adoption of IoT solutions. For VU, this project allows us to continue with the research and development initiated in the InterConnect project on data interoperability and explainable machine learning for smart buildings.

Researchers from the User-Centric Data Science group will participate in the project mostly in the context of the Dutch pilot, which will run in Arnhems Buiten, the former testing location of KEMA in the east of the Netherlands. In the pilot, we will collaborate closely with the other Dutch partners: TNO and Arnhems Buiten. At this site, an innovative business park is being realized that has its own power grid architecture, allowing for exchange of data and energy, opening the possibility for various AI-driven services for end-users.

VU will research a) how such data can be made interoperable and enriched with external information and knowledge and b) how such data can be made accessible to services and end-users through data dashboards that include explainable AI.

The image above shows the Arnhems Buiten buildings and the energy grid (source: Arnhems Buiten)

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