Construction contributes significantly to gas emissions. Diverse efforts have been undertaken to mitigate the effects of these emissions; however, there currently is no effective tool to estimate small-scale (e.g., project-based) emissions in construction. Discrete-event simulation (DES), a new approach, may be able to rectify this lack. This research has built a DES-based emission template using Simphony, a special purpose simulation (SPS) environment developed at the University of Alberta. This template permits inexperienced simulators to build simulation models that can estimate emissions of a construction project. Two case studies are used to showcase the modeling process and to demonstrate how valuable information concerning sustainability can be obtained through this method. In addition, this research introduces an emission federate in a high-level architecture (HLA) simulation environment that can estimate emissions without building models; it relies instead upon information provided by other federates (e.g., operation federate), which has been underdeveloped thus far. / Construction Engineering and Management

With the increasing developments of exploiting oil and natural gas in deep water and harnessing renewable (wave and wind) energy in the sea, mooring lines and risers are widely deployed to position the related floating structures. Subject to environmental loads, a mooring line or riser connected to floating structure, moves up and down, back and forth, and sometimes from the left to the right. In computation of the dynamics of a mooring line or riser, it is often modeled as a flexible slender rod. While the bending moment of a chain or a rope is neglected, that of a riser is considered and specified by characteristics of the riser. Existing numerical codes for simulating the dynamics of a slender rod, such as CABLE3D, allow for the vertical support force and longitudinal (along the direction of the rod) friction from soils of the seabed while the transverse (in the direction transverse to the slender rod) friction between the rod and the seabed soils is not considered. In this study, we extend the current version of CABLE3D to allow for the transverse friction applied on the portion of a slender rod contacting the seabed soil, which is time-varying when it is moving. The friction between a slender rod and the seabed soil is computed based upon a Coulomb model originally developed for the simulation of the friction in all dry contact mechanical systems. In applying the Coulomb model, the transverse friction depends on the transverse displacement and/or velocity of a slender rod contacting the seabed. In addition, vertical bottom support of the seabed soil is calculated based on the shear stress of the seabed soil. The simulations of the dynamics of a few typical mooring lines are made given their motions at their fairleads and the results are compared with the corresponding results obtained using Orcaflex, a commercial code, and the existing version of CABLE3D.

Thesis (M.S.)--University of Hawaii at Manoa, 2007. / Includes bibliographical references (leaves 71-74). / xi, 74 leaves, bound ill. 29 cm

Thesis (M.S.)--University of Hawaii at Manoa, 2005. / Includes bibliographical references (leaves 72-73). / viii, 73 leaves, bound ill. 29 cm

Navigating in the arctic has become more common, but it is dicult and dangerousdue to the presence of ice. Any training under safer circumstances is therefore veryvaluable, enter the need for ship simulators. Ship simulators today incorporate manyfeatures, such as cranes, anchors, wires, and state of the art physics. However, theinclusion of ice is very rare due to the complexity of simulating the feedback from theice breaking progress.The purpose of this project is to build a model and numerical methods to simulate icefracture in real-time, which is to be used in ship simulators. The model presented inthis project is implemented with the use of the physics engine AgX Multiphysics madeby Algoryx Simulation ABThe method represents the ice sheet as a non-homogeneous mesh. A collision with thehull of the ship injects deformation energy into the ice. The energy from the inelasticimpact is distributed on the ice sheet according to a quasi-static crack propagationmodel that is dened on a static mesh. The cracks are guided using stress elds thatapproximate the strain in each vertex. The distribution of the strain is done by a simplemodel which allows for breaking ice in non-uniform fragments. This is more realisticthan fracture in predened shapes which is the main contribution of this project. Thefragments become unbreakable rigid body ice oes that interact with the ship's hull bycollision and friction.The implementation of the ice model is tested by using a trimesh model of the TorViking II icebreaker using approximated buoyancy calculations, damping equations,and engine forces.Real-time performance is not achieved yet in the general case, but this is due to thechoice of collision geometry and the oe creation. Unstable force spikes from thecontacts between the ship and the ice is detected, but the overall global ice resistanceshows few abnormalities. Replacing the collision geometry and the rigid body oes isnecessary for the implementation to be able to run in real-time. Further experimentsto compare with real model data is needed to be able to validate the model.

A simulation study was used to analyze the flow of products though a sawmill in order to determine where productivity improvements could be made. The sawmill analyzed is located in the interior of British Columbia, and processes a variety of species and products. The mill was selected for this reason, as it was important to determine how a change in the process will affect the piece flow and production of the various species. A simulation model of the mill was developed using the Arena 8.0 discrete event simulation software developed by Rockwell Automation. Data consisting of mill layout and flow, breakdown patterns, machine process times and downtimes, conveyor speeds, and buffer capacities were collected from the sawmill. This information was used to layout the framework in a conceptual model. The conceptual model was then used to develop the simulation model in Arena. A face validity test, combined with comparisons of model output to actual mill output was used to determine the validity of the model. After running several different scenarios processing Larch, White pine, and Ponderosa pine, it was discovered that the trimmer was the system bottleneck when both the small log and large log lines were running throughout the shift. Running under base case conditions, the model predicted an average board output of 13,147 boards. An increase in the processing capability of the trimmer resulted in the bottleneck to shift to the edger from the small log line. The OptQuest Analyzer program bundled with the Arena software was used to further analyze the shift in bottleneck to the edger from the small log line. By allowing the program to manipulate machine settings for the trimmer and edger, it was able to maximize the average board output to 17,996 boards per shift when no edger set up times were considered. If the edger setup times are used, the average board output dropped to 16,708 boards per shift. These findings were presented to the sawmill management and based on the study, they proceeded to make improvements at the trimmer. The improvements resulted in an increase of 10% to sawmill output.

Simulation provides the ability to obtain results from, and analyse, a system without physically building the system. These results can be used to inform the actual construction of the physical system, how best to use a system, how best to integrate a system with another system, and so on. A simulation can also be used to train and educate the end-users of a system either before the system is actually produced or when the availability of the actual system is limited. Most end systems are in some way composed of subsystems. The subsystems themselves may be composed of subsystems. This type of architecture is generically referred to as a system of systems. For example, a ship is composed of a hull, engines, sensors, etc. The engine system may be composed of the fuel and cooling subsystems, for example. Systems constructed this way have numerous benefits including allowing subsystems to be built independently of each other (after creating well defined interfaces), and allowing for subsystems to be replaced without affecting other subsystems. These same benefits are desirable in the construction of a simulation of a system. One simulation framework that supports these ideals is the High Level Architecture (HLA). The HLA is an international modelling and simulation framework that specifically provides for distributed simulation. The HLA uses the term federate for component simulations that are then brought together in a distributed computing environment to form a federation. The HLA defines a data model for documenting the data interfaces of the federates and the application programming interface used by the federates to communicate data. A simulation of a systems of systems architecture can be implemented in the HLA by creating federates for each subsystem and defining the data communicated between subsystems in terms of HLA’s data model. HLA’s default communication model defines publishers and subscribers of data classes. The HLA provides class based filtering, i.e., a federate only receives data for a data class to which it has subscribed. However, HLA’s default communication model has no notion of direct ‘wiring’ between federates. Thus, it is not possible to have data sent to a specific federate. This creates a problem if multiple instances of a system of systems are simulated concurrently, which may be desirable so as to observe the interactions between systems. In this case, the data sent within one system is exposed to all other systems in the simulation. This thesis explores this problem of simulating multiple systems of systems using the HLA. The problem is stated formally by introducing the concept of a message path and showing that a federation containing multiple systems of systems contains incorrect message paths which communicate intra-system data between systems. Three methods are presented and shown to solve the problem by either eliminating the incorrect message paths or allowing a receiving federate to determine whether intra-system data was delivered via an incorrect message path. The three solutions are Local Data Filtering (LDF), Data Distribution Management (DDM), and Federation Communities (FC). The LDF solution marks all intra-system data with a system identifier, allowing receivers to distinguish whether they should process it. The DDM method uses a service defined by the HLA that essentially provides an automated version of the LDF solution. The FC method restricts one federation to simulating one system and requires a multiple system simulation to enable inter-federation communication, something that is not defined in the HLA. These three methods are analysed both quantitatively and qualitatively. The quantitative analysis looks at performance overhead imposed by each method and how well each method reduces the number of incorrect intra-system messages communicated. The qualitative analysis is presented in terms of identifying the complexity of implementing each method for a specific systems of systems federation: the election process for the Australian federal government. The thesis concludes that the LDF method is simple to understand but potentially finicky to implement and is wasteful of network resources. The DDMmethod is advantageous in that it is a service defined by the HLA standard. However, the implementation of the DDM services by a Runtime Infrastructure (RTI) is not defined by the HLA. Thus, the performance of the DDMmethod is coupled to a specific RTI and its configurability. The FC method achieves an ideal of replicating the simulation of a single system without modification to achieve a multisystem simulation. However, it requires and inter-federation communicationmechanism that is not defined by the HLA. The FC method introduces extra latency and reduced throughput to inter-system messages in a Local Area Network (LAN) environment. / Thesis (Ph.D.) -- University of Adelaide, School of Computer Science, 2009

Scientific computer simulation involves interacting with a mathematical model, in a way that is analogous to performing a laboratory experiment. Based on interviews with scientists, using a framework of grounded theory and symbolic interactionist sociology, the thesis describes crucial features of this novel mode of scientific work. A dualistic comparison of simulation with ‘theory’ and ‘experiment’ (in the second chapter) gives rise to two apparently independent discussions: of the ‘experilnental’ practices associated with simulation (chapter three), and of the ‘theoretical’ concerns that shape the technique (chapter four). Those discussions are drawn together in chapter five, which describes the interdependence of those two essential aspects of simulation. (For complete abstract open document)

Zugl.: Hamburg, Universiẗat, Diplomarbeit.

Thesis (M.S. - Hydrology and Water Resources)--University of Arizona. / Includes bibliographical references.