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Title: Determination of density and moisture content of wood using Terahertz time domain spectroscopy.
Contributors: Belal Ahmed (author), Ian Hartley (Thesis advisor), University of Northern British Columbia (Degree granting institution)
Abstract: Terahertz time-domain spectroscopy was used to simultaneously predict the density and moisture content of four wood species (Aspen, Birch, Hemlock and Fir). Using a fixed value for the dielectric function of water, it was found that moisture content was systematically underestimated at low moisture contents, which results from changes in the dielectric function of water as it goes from free to bound in nature. The variation of the dielectric function of water with moisture content was studied further, and the results show that the dielectric function of water does indeed change with moisture content. The results are a large step forward in our understanding of wood-water interactions at Terahertz frequencies, and therefore useful for applications in wood science. --Leaf i.
Discipline: Physics
Date added: 2017-04-11T21:13:11.575Z

Title: A one-dimensional special relativistic shock tube where stellar fluid undergoes neutrino heating.
Contributors: Gregory Mohammed (author), Erik Jensen (Thesis advisor), Patrick Mann (Thesis advisor), University of Northern British Columbia (Degree granting institution)
Abstract: Stellar models attempt to reproduce supernovae via core collapse processes which are created in numerical simulations. Recent advances in the understanding of supernovae processes as well as in computer hardware technologies are producing increasingly sophisticated multi-dimensional supernova simulations. Some of the processes involved are neutron capture, radioactive decay, the different fusion branches and the neutrinos they produce, neutrino high-energy physics, neutrino-matter interaction and neutrino scattering. This thesis is a simulation of the behavior of stellar fluid undergoing neutrino heating in a shock tube. --Leaf 1.
Discipline: Physics
Date added: 2017-03-30T17:12:55.472Z

Title: Efficiency calibration measurement and GEANT simulation of the DRAGON BGO gamma ray array at TRIUMF.
Contributors: Dario G. Gigliotti (author), Ahmed Hussein (Thesis advisor), University of Northern British Columbia (Degree granting institution)
Abstract: A gamma ray array to detect the characteristic gammas emitted from astrophysically significant, radiative proton and alpha capture reactions, was built as part of the Detector of Recoils And Gammas Of Nuclear reactions (DRAGON) spectrometer at ISAC/TRIUMF. The DRAGON array consists of a collection of 30 hexagonal BGO detectors measuring 7.62 cm long by 5.58 cm across the face. A simulation was built with the particle-tracking program GEANT v3.21. The efficiency of the array was measured using calibrated sources of various gamma energies and compared to simulated results. For the cases where the activity of the source was not well known the sources were calibrated using a standard NaI detector of known efficiency. The agreement between simulation and measured differences is more than adequate for proposed DRAGON experiments. The analysis and results of the comparison between measured and simulated efficiency will be discussed in this thesis.
Discipline: Physics
Date added: 2017-03-30T16:59:24.506Z

Title: Acoustic and adsorption properties of submerged wood.
Contributors: Calvin Patrick Hilde (author), Ian Hartley (Thesis advisor), University of Northern British Columbia (Degree granting institution)
Abstract: Wood is a common material for the manufacture of many products. Submerged wood, in particular, is used in niche markets, such as the creation of musical instruments. An initial study performed on submerged wood from Ootsa Lake, British Columbia, provided results that showed that the wood was not suitable for musical instruments. This thesis re-examined the submerged wood samples. After allowing the wood to age unabated in a laboratory setting, the wood was retested under the hypothesis that the physical acoustic characteristics would improve. It was shown, however, that the acoustic properties became less adequate after being left to sit. The adsorption properties of the submerged wood were examined to show that the submerged wood had a larger accessible area of wood than that of control wood samples. This implied a lower amount of crystalline area within the submerged wood. From the combined adsorption and acoustic data for the submerged wood, relationships between the moisture content and speed of sound were created and combined with previous research to create a proposed model to describe how the speed of sound varies with temperature, moisture content and the moisture content corresponding to complete hydration of sorption sites within the wood. --P. ii.
Discipline: Physics
Date added: 2017-03-30T17:10:33.941Z

Title: Single-frequency terahertz Michelson interferometer for applications in wood products
Contributors: Kimberly Amanda Lawyer (author), Matthew Reid (Thesis advisor), Mark Shegelski (Thesis advisor), University of Northern British Columbia (Degree granting institution)
Abstract: There is an ever-growing demand in the wood products industry for cost-effective and compact equipment to ensure wood quality measures and specifications are met. Recently, terahertz (THz) technology has begun to pave the way for new, non-destructive imaging techniques rather than the standard use of X-ray or microwave technology. A prototype THz Michelson interferometer operating at 0.102 THz was developed to measure the indices of refraction and absorption coefficients of maple, hemlock and birch. These measurements were compared to the Picometrix system, which uses conventional THz time-domain spectroscopy and has been implemented in an industrial setting for the real-time measurement of the density of OSB flakes. However, the cost and complexity of the Picometrix system prohibits its use for many industrial applications. The interferometer is cost-effective, compact and provides accurate data at low THz frequencies, thus providing an excellent alternative direction for new THz technology in the wood products industry. --Leaf ii.
Discipline: Physics
Date added: 2017-03-29T17:30:00.292Z

Title: Speckle pattern based single pixel imaging
Contributors: Patrick Kilcullen (author), Matthew Reid (thesis advisor), Mark Shegelski (thesis advisor), University of Northern British Columbia College of Science and Management (Degree granting institution), Edward Dobrowolski (committee member)
Abstract: This thesis introduces a new modality for terahertz single pixel imaging which takes advantage of compressive sensing techniques and random speckle patterns. This proposed modality offers a new trade-off in complexity and speed in comparison to current imaging systems with the introduction of a spatial light modulator that is minimally simple and inexpensive. Experimental results are obtained exhibiting the successful application of this technique. Extensions and applications of the proposed technique are also discussed.
Discipline: Physics
Date added: 2017-05-15T21:24:17.03Z

Title: Modelling heat transfer in the conditioning process used in plywood manufacturing.
Contributors: Dino A. Gigliotti (author), Patrick Montgomery (Thesis advisor), Patrick Mann (Thesis advisor), University of Northern British Columbia (Degree granting institution)
Abstract: As part of an industrial process in the forestry industry, pre-cut segments of debarked logs are conditioned by placing the wood segments in a warm water shower. For wood which is initially cold (or sometimes frozen) and has a relatively high moisture content, the conditioning process results in a net increase in temperature and change in moisture content. As a porous media, wood has a fairly complex structure due to the orientation and sizes of the cells which make up the fibers. In addition, the moisture content of the recently debarked log segments is relatively high, the moisture being almost completely composed of liquid water trapped by capillary forces. Simplistic models which assume a constant moisture content have previously been used to predict conditioning time. However, as is often the case in reality, the complexity of the problem is such that more accurate modelling is desired. To learn more about the conditioning process, preliminary experiments were conducted using a data logger and an array of fifteen thermocouples placed radially at three points on a log segment which was then put through a full conditioning cycle. Theoretical model equations are presented, which take into account both the liquid and vapour components of the waters, and spatial averaging is used to create a system of nonlinear partial differential equations. The problem is then simplified through some basic assumptions to pose a set of coupled differential equations for energy and moisture transport in one spatial dimension. A finite difference numerical method is used to solve the initial boundary value problem for the coupled system of nonlinear partial differential equations, and some numerical results are compared to experimental data for the one dimensional problem. Limitations of the model are identified and discussed.
Discipline: Physics
Date added: 2017-03-30T17:05:22.253Z

Title: True quantum teleportation
Contributors: Lara Pow (author), Mark Shegelski (Thesis advisor), University of Northern British Columbia (Degree granting institution)
Abstract: Quantum teleportation has been investigated experimentally, for a variety of physical systems. However, it has been suggested that most methods of teleportation do not achieve true teleportation. This is because a complete Bell-operator measurement cannot be performed without interaction between the quantum particles involved in the teleportation. Since the Bell-operator measurement is a key factor in the teleportation procedure, teleportation cannot be realized in the manner proposed in the pioneering paper on teleportation. In this project, it is verified that, without interaction between the quantum particles involved in the teleportation procedure, true teleportation cannot be achieved.--Page ii.
Discipline: Physics
Date added: 2017-04-10T22:10:35.059Z

Title: Determination of the origin of birefringence in wood at terahertz frequencies.
Contributors: Tara Marie Todoruk (author), Matthew Reid (Thesis advisor), Ian Hartley (Thesis advisor), University of Northern British Columbia (Degree granting institution)
Abstract: In the wood products industry, terahertz (THz) radiation is an emerging technology that is showing promise for new types of monitoring. These applications are dependent on the ability of THz radiation to probe the gross fibre structure of wood. The sensitivity to this gross fibre structure results from strong birefringence at THz frequencies. Prior to this thesis work, the nature of the birefringence exhibited in wood was an open question. Based on the physical structure of wood, the large birefringence observed can be due to intrinsic birefringence, resulting from the dielectric properties of the wood material present in the cell walls, or form birefringence, resulting from the repetitive array of cylindrical cells present in the wood structure. This thesis determines for the first time the origin of birefringence at THz frequencies in wood. This question is important to potential applications in the wood products industries because if the birefringence has a large contribution from form birefringence, then it is the gross fibre structure of wood products that is being probed by THz radiation, which opens the door to applications in non-contact, non-destructing strength testing for example. This thesis outlines a number of systematic studies that will address the relative contributions of form and intrinsic birefringence to the large birefringence seen in wood at THz frequencies, and demonstrate, for the first time, what the source of this large birefringence is in several different species of wood. --P. ii.
Discipline: Physics
Date added: 2017-03-30T17:05:14.832Z

Title: Photodissociation dynamics of molecules on surfaces.
Contributors: Chris C. Johnson (author), Erik T. Jensen (Thesis advisor), University of Northern British Columbia (Degree granting institution)
Abstract: No abstract available.
Discipline: Physics
Date added: 2017-03-30T16:58:04.141Z

Title: Terahertz spectroscopy of nitric oxide for emissions monitoring in bioenergy systems
Contributors: Ahmed Adel Nasreldin Mohamed (author), Mark Shegelski (Thesis advisor), Matthew Reid (Thesis advisor), University of Northern British Columbia College of Science and Management (Degree granting institution), Kerry Reimer (Committee member), Erik Jensen (Committee member), Hossein Kazemian (Committee member)
Abstract: The aim of this thesis is to study pollutants that are emitted from combustion systems using Terahertz time domain spectroscopy (THz-TDS). In particular, this thesis will focus on Nitric Oxide (NO), which is present in flue gases and contributes to air pollution. It is also interesting from a Physics perspective because it contains an unpaired electron in the valence shell, which leads to a complicated energy level structure, and interesting Physics. In this thesis, we aim to answer the question: “what is the detection limit of NO, using THz-TDS, and is it suitable for industrial emissions monitoring?” It is therefore necessary to look at detection limits, which in turn requires conducting THz spectroscopy at different gas pressures. ...
Discipline: Physics
Date added: 2017-05-15T21:10:45.274Z

Title: Quantum tunnelling of a molecule with a single bound state.
Contributors: Jeremy J. Kavka (author), Mark Shegelski (Thesis advisor), University of Northern British Columbia (Degree granting institution)
Abstract: We investigate, in one spatial dimension, the quantum mechanical tunnelling of a diatomic, homogeneous molecule with a single bound state incident upon an external barrier. Both time-independent and time-dependent tunnelling are investigated, using analytical and numerical methods. In the time-independent case, we first derive a formal solution for the molecule's wave function. Then, using the method of variable reflection and transmission amplitudes, we find that the probabilities of reflection and transmission in the bound state decrease with decreased binding strength, while the probabilities of refection and transmission in an unbound state increase with decreased binding energy. In the time-dependent case, we consider a molecule with discrete unbound states. The molecular wave function is modeled as a Gaussian wave packet, and its propagation is calculated numerically using Crank-Nicholson integration. It is found that, in addition to reflecting and transmitting, the molecule may also straddle the potential barrier in an unbound state.
Discipline: Physics
Date added: 2017-03-30T17:06:38.267Z

Title: Tunneling of a diatomic molecule incident upon a potential barrier.
Contributors: Glen L. Goodvin (author), Mark Shegelski (Thesis advisor), University of Northern British Columbia (Degree granting institution)
Abstract: No abstract available.
Discipline: Physics
Date added: 2017-03-30T17:01:50.023Z

Title: Probing the potential applications of terahertz radiation in wood products
Contributors: Jonathan Michael Schneider (author), Matthew Reid (Thesis advisor), Ian Hartley (Thesis advisor), University of Northern British Columbia (Degree granting institution)
Abstract: In the wood products industry, terahertz (THz) radiation is showing promise as a new remote sensing technology with many applications. The purpose of this project was to probe the interaction of terahertz radiation with wood to determine the extent of these possibilities. Three avenues of study were undertaken: 1. Probe the cylindrical structure of wood in a reflection geometry, 2. Study the birefringence of different species of oven dry wood, 3. Study the extinction coefficient of different species of oven dry wood. These three studies increased our understanding of the interaction between THz radiation and wood. Prior to this study, the extinction mechanism in THz transmission through wood was an open question. Three mechanisms were identified: absorption by the vibrational and rotational modes of the wood and water molecules scattering by the dielectric cylindrical wood cells and, diffraction by the earlywood-latewood pattern. This project determined that absorption by the wood and water molecules is the dominant extinction mechanism in transmission through wood, contributing to ~90% of the signal attenuation. --P. i.
Discipline: Physics
Date added: 2017-04-10T22:05:38.763Z

Title: Tunneling of a diatomic molecule with transitional channels and molecular break-up.
Contributors: John Roman Koblanski (author), Mark Shegelski (Thesis advisor), University of Northern British Columbia (Degree granting institution)
Abstract: We study a diatomic homonuclear molecule incident upon a potential barrier. We allow for transitions among bound states and for molecular break-up for a molecule incident upon the barrier in a bound state. We apply an elegant method to calculate probabilities of reflection and transmission, in bound and unbound states. In the numerical work, we use a binding potential that captures the important physical features of real potentials and a single delta barrier for the potential barrier. We showed that the probabilities of reflection and transmission in unbound states were small compared to the probabilities of reflection and transmission in bound states. We also found that the probabilities of reflection and transmission decrease for large kinetic energies. For a molecule with only one bound state, it was shown, using two different binding potentials, that the probabilities of reflection and transmission in unbound states were also small. We showed that an arbitrarily weakly-bound molecule will break up upon encountering a barrier. We also discussed a shortcoming of the results and possible resolutions. Suggestions for further studies were also presented.--P.ii.
Discipline: Physics
Date added: 2017-03-30T17:03:19.907Z

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