The definition of room functions in Building Information Modeling (BIM) using IfcSpace entities is an important quality requirement that is often not fulfilled. This paper presents a three-step method for enriching open BIM representations based on Industry Foundation Classes (IFC) with room function information (e.g., kitchen, living room, foyer). In the first step, the geometric algorithm for detecting and defining IfcSpace entities and injecting them into IFC models is presented. After deriving the IfcSpaces, a geometric method for calculating the graph of connections between spaces based on accessibility is described; this information is not explicitly stored in IFC models. In the final step, a graph convolution-based neural network using the accessibility graph to classify the IfcSpace entities is described. Local node features are automatically extracted from the geometry and neighboring elements. With the help of a Graph Convolutional Network (GCN), the connection and spatial context information is utilized by the neural network for the classification decision, in addition to the local features of the spaces which are more commonly used. To evaluate the classification accuracy, the model was tested on a set of residential building IFC models. A weighted version of the common GCN was implemented and tested, resulting in a slight improvement in the classification accuracy.

A strain-free superlattice of inversion domains along the hexagonal axis of SiC is investigated by theoretical calculations. The induced polarization causes a zigzag shape in the band edges, leading to spatial separation of photoexcited carriers and to an effective band gap narrowing tunable over a wide range by the geometry and on a smaller scale by the intensity of the excitation. Calculations on the SiC surface indicate that preparation of such a superlattice might be possible in atomic layer epitaxy with properly chosen sources and temperatures.

Decarbonization of industrial processes by using high-temperature heat pumps is one of the most important pillars towards sustainable energy goals. Most heat pumps are based on the standard Carnot cycle which includes an expansion valve leading to irreversible dissipation and energetic losses. Especially for high-temperature applications, these losses increase significantly, and a replacement of the conventional throttle valve with an ejector, which is an alternative expansion device, for partial recovery of some of the pressure lost during the expansion, is investigated in this paper. However, designing such a device is complicated as the flow inside is subject to multiphase and supersonic conditions. Therefore, this paper aims to streamline an approach for designing ejectors for high-temperature heat pumps using numerical simulations. To showcase the application of the design procedure, an ejector, which is used to upgrade a standard cycle high-temperature heat pump with the synthetic refrigerant R1233zdE, is developed. To design the ejector heat pump, an interaction between a fast 1D design tool, a 1D heat pump cycle simulation, and a 2D CFD simulation is proposed. An ejector is designed for a sink temperature of 130 °C, which can potentially increase the COP of the heat pump by around 20%. Preliminary measurements at off-design conditions at 100 °C sink temperature are used to validate the design procedure. The pressure distribution inside the ejector is well captured, with relative errors around 4%. However, the motive nozzle mass flow was underpredicted by around 30%. To summarize, the presented approach can be used for designing ejectors of high-temperature heat pumps, although the numerical modeling has to be further developed by validation with experiments to improve the prediction of the motive mass flow.