Massey Documents by Type

Permanent URI for this communityhttps://mro.massey.ac.nz/handle/10179/294

Browse

Subject: search.filters.subject.Models

Search Results

Now showing 1 - 3 of 3
  • Thumbnail Image
    Item
    Biomimetic gastric tract simulator : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Engineering at Massey University, Manawatu, New Zealand
    (Massey University, 2023) Olson, Gerald
    Mimicry of the biomechanical functioning of the human gastric tract can play a significant role in study of the behaviour of foods and food structures as they are broken down and digested in the human body. The gastric tract wall produces peristaltic waves and other deformation patterns providing movement, accommodation, mixing and evacuation of foods in the stomach and connected gastric tract organs. This thesis presents an advanced biomimetic dynamic in vitro model of the human gastric tract that simulates anatomic geometry and demonstrates the mixing and movement of gastric tract contents. Materials, methods, and techniques suitable for mimicking the gastric tract wall were investigated and artificial membrane layers, artificial muscles, muscle activation and control mechanisms, and feedback sensors were developed and integrated into a dynamic physical model of the gastric tract. A composite material of silicone rubber reinforced with a nylon elastic fabric provides a thin, watertight, and highly elastic artificial membrane that forms the shell of the tract. Artificial muscles made from loops of coiled nylon monofilament line, attached to the artificial membrane, are contracted, and expanded through the pulling and releasing of flexible tendons or cables. Contraction and expansion of the artificial muscles is carried out using winding mechanisms and motors, while feedback and control systems track and maintain the desired mechanical activity of the tract. Mimicry of the muscle and membrane layers of the gastric tract wall is a novel approach to simulating gastric tract biomechanics, resulting in a soft, highly flexible, and dynamic physical in vitro modelling of the geometrical, anatomic, and biomechanical functioning of the human gastric tract.
  • Thumbnail Image
    Item
    Graph theoretic and electronic properties of fullerenes, &, Biasing molecular modelling simulations with experimental residual dipolar couplings : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy at Massey University, Albany, New Zealand
    (Massey University, 2015) Wirz, Lukas N
    In this thesis two different models, that is levels of abstraction, are used to explore specific classes of molecular structures and their properties. In part I, fullerenes and other all-carbon cages are investigated using graphs as a representation of their molecular structure. By this means the large isomer space, simple molecular properties as well as pure graph theoretical aspects of the underlying graphs are explored. Although chemical graphs are used to represent other classes of molecules, cavernous carbon molecules are particularly well suited for this level of abstraction due to their large number of isomers with only one atom type and uniform hybridisation throughout the molecule. In part II, a force field for molecular dynamics, that is the step wise propagation of a molecular structure in time using Newtonian mechanics, is complemented by an additional term that takes into account residual dipolar couplings that are experimentally measured in NMR experiments. Adding this force term leads to more accurate simulated dynamics which is especially important for proteins whose functionality in many cases crucially depends on their dynamics. Large biomolecules are an example of chemical systems that are too large for treatment with quantum chemical methods but at the same time have an electronic structure that is simple enough for accurate simulations with a forcefield.
  • Thumbnail Image
    Item
    Towards a comprehensive model for the positive electrode system of a lead-acid traction cell : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Production Technology at Massey University
    (Massey University, 1989) Nilson, Ross Richard
    This thesis develops a detailed model for the positive electrode system of an industrial lead-acid traction cell. This is referred to as the VIAM model since it relates the positive electrode voltage (V) and cell current (I) to internal distributions of current, potential, acid concentration and active mass (AM). The model can simulate both discharge and charge for a wide range of practical currents. The model takes account of microstructure, macrostructure and non-reactive structure in the positive active mas (AM). It also takes account of other cell components that affect the supply of acid to the positive electrode. The model has direct application to fundamental cell design (for example AM development) and cell systems design (for example cell charger design). The model is based on established experimental studies, theories of electro chemical interface reactions and theories of ionic transport in electrolyte solution. From this base, three elemental models and an aggregate model are developed. The elemental models represent details of the microstructure of the positive electrode AM. The aggregate model represents the electrolyte mass (acid) and charge transport system within the positive electrode and other cell components. The combination of the elemental and aggregate models make up the VIAM model. The performance of the VIAM model (and underlying models) is assessed by comparing model results with findings from experimental studies in the literature. In addition, experiments undertaken as part of this work are used to test the model. The model and experimental results are in close agreement.