BIM-based construction simulation modelling

Construction simulation has been widely used in academia for research purposes and its usefulness as a planning and decision-making support tool has been proven. However, it has been neglected by the industry for various reasons, including the amount of data, skills, effort and time required to develop complex simulation models, the difficulty of model reuse, and the abstract and confusing way in which simulation results are usually presented. This thesis proposes a simulation modelling approach that leverages existing simulation modelling paradigms used in the context of construction engineering and management, namely, discrete-event simulation, distributed simulation, hierarchical control structures and parametric modelling. The proposed simulation modelling approach enables an accurate representation of resource allocation and task interdependencies constraints while enabling model reuse to streamline the process of developing complex simulation models. Moreover, the proposed simulation approach provides a mechanism to enhance the visualisation of simulation results by generating simulation-based animations, which can be used for different visualisation purposes. The thesis discusses how the proposed simulation approach could tackle some of the barriers to adopting simulation in the industry. Subsequently, the thesis presents a framework for the semi-automatic generation of a construction simulation model and animations of its results from a building information model (BIM). The development of the proposed conceptual framework was based on the proposed simulation modelling approach. The framework is composed of five main modules: (1) the environment module, preloaded with a library of generic simulation models of different construction activities, (2) the user input, which includes the facility to import existing BIM models, (3) the preprocessing module, which automatically generates a BIM-based simulation model, (4) the simulation module, in which users can experiment with the model, and (5) the visualisation module, which produces reports and simulation-based animations to support planning and decision-making. The proposed conceptual framework and its components were tested by designing a game engine-based application implemented in the Unity game engine. The features of the selected game engine were exploited to achieve the intended functionality of the framework. The feasibility of the framework was assessed through a case study based on a typical masonry construction problem. Results of implementing the framework reveal that BIM-based simulations can reduce the skills, effort and time required to develop simulation models, and enable model reuse. The integration of simulation-based animations provides a model verification and validation mechanism, and a means to communicate model results to stakeholders that are unfamiliar with simulation

Shingle 2.0: generalising self-consistent and automated domain discretisation for multi-scale geophysical models

The approaches taken to describe and develop spatial discretisations of the domains required for geophysical simulation models are commonly ad hoc, model or application specific and under-documented. This is particularly acute for simulation models that are flexible in their use of multi-scale, anisotropic, fully unstructured meshes where a relatively large number of heterogeneous parameters are required to constrain their full description. As a consequence, it can be difficult to reproduce simulations, ensure a provenance in model data handling and initialisation, and a challenge to conduct model intercomparisons rigorously. This paper takes a novel approach to spatial discretisation, considering it much like a numerical simulation model problem of its own. It introduces a generalised, extensible, self-documenting approach to carefully describe, and necessarily fully, the constraints over the heterogeneous parameter space that determine how a domain is spatially discretised. This additionally provides a method to accurately record these constraints, using high-level natural language based abstractions, that enables full accounts of provenance, sharing and distribution. Together with this description, a generalised consistent approach to unstructured mesh generation for geophysical models is developed, that is automated, robust and repeatable, quick-to-draft, rigorously verified and consistent to the source data throughout. This interprets the description above to execute a self-consistent spatial discretisation process, which is automatically validated to expected discrete characteristics and metrics.Comment: 18 pages, 10 figures, 1 table. Submitted for publication and under revie

Object-oriented modelling of solar district heating grids with underground thermal energy storage

The transformation of the heating sector towards renewable energy sources is a key element for the mitigation of man-made climate change. In this regard, solar thermal energy is a particularly well-suited solution, as it is a simple, cost-efficient and proven technology. A main barrier for a more widespread use, is the seasonal mismatch of heat demands and solar yields, which usually limits the solar share on the overall heat supply of district energy systems to about 20%. It is therefore necessary to store the abundant solar energy supply during summer for several months to be able to use it in winter. Underground thermal energy storage (UTES) is currently the most promising technology for such applications, as it shows a high maturity level in comparison to other technologies and facilitates storage of thermal energy on a district scale. Integration of UTES into solar district heating (SDH) systems is commonly accompanied by further technologies, such as geothermal energy, industrial waste heat or power-to-heat applications, resulting in complex energy systems. These SDH-UTES systems require a thorough design of component dimensions, system layouts and control strategies to ensure security of supply, while avoiding costly overdimensioning of generation capacities. Therefore, dynamic system simulations are used for system design, as they consider the temporal distribution of heat supplies and demands as well as the strong interactions between components. The modelling language Modelica constitutes a powerful conceptual approach for modelling and simulation of thermal energy systems and is therefore applied increasingly. However, to exploit Modelica’s numerous advantages for the simulation of SDH-UTES systems and reach a large number of users, adequate model libraries are required. These should be accurate in their representation of physical components, easy to use and have a low numerical effort. The presented cumulative dissertation and the corresponding publications in scientific journals demonstrate the development of such a model library called MoSDH (Modelica Solar Dis-trict Heating). The library consists of components for the accurate, efficient, user friendly and robust simulation of such systems, including models for UTES technologies which were previously not implemented for Modelica. Selected models and aspects were already presented and demonstrated in case studies in the above-mentioned journal papers. The presented thesis contains a comprehensive description of the model components as well as the general system modelling concept. Furthermore, several case studies are used to highlight certain key functionalities and demonstrate the accurate representation of the physical systems in a numerically efficient way. The models can be used for extensive optimization studies as well as detailed investigations of certain specific aspects. In addition to that, the object-oriented modelling approach facilitates the easy adaption and reuse of model components. Finally, MoSDH is used to investigate the transition of a sub-grid of the TU Darmstadt university district heating (DH) system into a SDH-UTES system, demonstrating the possibility of those systems to satisfy the universities emission saving goals in a cost-efficient way

BIM-based construction simulation modelling

Construction simulation has been widely used in academia for research purposes and its usefulness as a planning and decision-making support tool has been proven. However, it has been neglected by the industry for various reasons, including the amount of data, skills, effort and time required to develop complex simulation models, the difficulty of model reuse, and the abstract and confusing way in which simulation results are usually presented. This thesis proposes a simulation modelling approach that leverages existing simulation modelling paradigms used in the context of construction engineering and management, namely, discrete-event simulation, distributed simulation, hierarchical control structures and parametric modelling. The proposed simulation modelling approach enables an accurate representation of resource allocation and task interdependencies constraints while enabling model reuse to streamline the process of developing complex simulation models. Moreover, the proposed simulation approach provides a mechanism to enhance the visualisation of simulation results by generating simulation-based animations, which can be used for different visualisation purposes. The thesis discusses how the proposed simulation approach could tackle some of the barriers to adopting simulation in the industry. Subsequently, the thesis presents a framework for the semi-automatic generation of a construction simulation model and animations of its results from a building information model (BIM). The development of the proposed conceptual framework was based on the proposed simulation modelling approach. The framework is composed of five main modules: (1) the environment module, preloaded with a library of generic simulation models of different construction activities, (2) the user input, which includes the facility to import existing BIM models, (3) the preprocessing module, which automatically generates a BIM-based simulation model, (4) the simulation module, in which users can experiment with the model, and (5) the visualisation module, which produces reports and simulation-based animations to support planning and decision-making. The proposed conceptual framework and its components were tested by designing a game engine-based application implemented in the Unity game engine. The features of the selected game engine were exploited to achieve the intended functionality of the framework. The feasibility of the framework was assessed through a case study based on a typical masonry construction problem. Results of implementing the framework reveal that BIM-based simulations can reduce the skills, effort and time required to develop simulation models, and enable model reuse. The integration of simulation-based animations provides a model verification and validation mechanism, and a means to communicate model results to stakeholders that are unfamiliar with simulation

Modeling, Simulation and Emulation of Intelligent Domotic Environments

Intelligent Domotic Environments are a promising approach, based on semantic models and commercially off-the-shelf domotic technologies, to realize new intelligent buildings, but such complexity requires innovative design methodologies and tools for ensuring correctness. Suitable simulation and emulation approaches and tools must be adopted to allow designers to experiment with their ideas and to incrementally verify designed policies in a scenario where the environment is partly emulated and partly composed of real devices. This paper describes a framework, which exploits UML2.0 state diagrams for automatic generation of device simulators from ontology-based descriptions of domotic environments. The DogSim simulator may simulate a complete building automation system in software, or may be integrated in the Dog Gateway, allowing partial simulation of virtual devices alongside with real devices. Experiments on a real home show that the approach is feasible and can easily address both simulation and emulation requirement

VSS : a VHDL synthesis system

This report describes a register transfer synthesis system that allows a designer to interact with the design process. The designer can modify the compiled design by changing the input description, selecting optimization and mapping strategies, or graphically changing the generated design schematic. The VHDL language is used for input and output descriptions. An intermediate representation which incorporates signal typing and component attributes simplifies compilation and facilitates design optimization. The compilation process consists of two phases. First, a design composed of generic components is synthesized from the input description. Second, this design is translated into components from a particular library by a mapper and optimized by a logic optimizer. Redesign to new technologies can be accomplished by changing only the component library