This thesis examines the widespread moisture problems which emerged over the past twenty years in buildings throughout coastal British Columbia, commonly known as ‘leaky condos’. A literature review of building physics and a historical review of wood-frame construction in North America provide background for this review. The purpose of this work is to report and interpret the performance of rainscreen walls in the coastal climate of Vancouver BC, based on extensive field data from five local buildings constructed or rehabilitated with rainscreen wall assemblies. Hygrothermal data was collected within exterior walls, and corresponding environmental data was recorded for each building. Driving rain loads at the five buildings across the city are calculated and compared to Vancouver airport data. Site factors are shown to have a significant impact on driving rain load, wind speed and direction. The WUFI 4.1 hygrothermal model was compared with the field data collected and found to be accurate at predicting past performance. Applying this validated model to each wall assembly, further simulations were performed to determine the impact of boundary conditions and assembly details on wall performance. Field measurements and modeling show that ventilated and drained claddings (i.e. rainscreen) reduce the sensitivity of wood frame buildings to moisture damage. Ventilation of the cladding is shown to be particularly important and natural buoyancy forces (from temperature and humidity differences between cavity and exterior) are usually sufficient to provide good drying. Exterior insulation is shown to further improve rainscreen wall performance by increasing the drying potential of the sheathing to both the exterior and interior. Additional work performed included material testing of fiberglass-faced gypsum sheathing and air-leakage testing of individual suites in the monitored buildings. Elevated interior humidity, resulting from inadequate ventilation, is shown to be exacerbated by inter-zonal air-flow in multi-unit residential buildings.

In the past 10 years, the bandwidths and processing capabilities of the networks have increased dramatically. The number of real-time applications using these networks has also increased. The large number of real-time packets might, in a switched multi-hop network, lead to unpredictable traffic patterns. This is not a problem when the traffic intensity is low, but if the same network is used by a large number of users simultaneously, the overall performance of the network degrades. In fact, unpredictable delays in the delivery of the message can adversely affect the execution of the tasks dependent on these messages, even if we take into account the soft real-time performance. In this paper, we investigate the effect of traffic shapers on soft real-time performance. We will consider a switched multi-hop network with FCFS queues. We will implement two versions of the network simulator. One version will be without traffic shaper and the other version will use a traffic shaper. By comparing the results (for average delay, deadline miss ratio etc.) from both the versions, we will try to conclude if it is really beneficial to use traffic shapers for soft real-time performance. Leaky bucket and token bucket algorithms are the most popular ones for traffic shaper implementation. We will consider leaky bucket algorithm for our analysis. We analyse different versions of the leaky bucket and present the trade-off’s involved.

This thesis examines the widespread moisture problems which emerged over the past twenty years in buildings throughout coastal British Columbia, commonly known as ‘leaky condos’. A literature review of building physics and a historical review of wood-frame construction in North America provide background for this review. The purpose of this work is to report and interpret the performance of rainscreen walls in the coastal climate of Vancouver BC, based on extensive field data from five local buildings constructed or rehabilitated with rainscreen wall assemblies. Hygrothermal data was collected within exterior walls, and corresponding environmental data was recorded for each building. Driving rain loads at the five buildings across the city are calculated and compared to Vancouver airport data. Site factors are shown to have a significant impact on driving rain load, wind speed and direction. The WUFI 4.1 hygrothermal model was compared with the field data collected and found to be accurate at predicting past performance. Applying this validated model to each wall assembly, further simulations were performed to determine the impact of boundary conditions and assembly details on wall performance. Field measurements and modeling show that ventilated and drained claddings (i.e. rainscreen) reduce the sensitivity of wood frame buildings to moisture damage. Ventilation of the cladding is shown to be particularly important and natural buoyancy forces (from temperature and humidity differences between cavity and exterior) are usually sufficient to provide good drying. Exterior insulation is shown to further improve rainscreen wall performance by increasing the drying potential of the sheathing to both the exterior and interior. Additional work performed included material testing of fiberglass-faced gypsum sheathing and air-leakage testing of individual suites in the monitored buildings. Elevated interior humidity, resulting from inadequate ventilation, is shown to be exacerbated by inter-zonal air-flow in multi-unit residential buildings.

The ultrasonic nondestructive technique is mainly used to evaluate interior defect, material properties and outside dimensions by measuring the transmitting and reflecting sound waves. Generally, the evaluation of the ultrasonic testing depends on the amplitudes and delay time of the received signals; however, this research is focused on the analysis of the phase differences of the received signals. The leakage phenomenon of surface waves propagating at the liquid-solid interface has been studied for more than fifty years. The main characteristic of this phenomenon is the 180-degree phase difference between the reflected and leaky ultrasound when a bounded ultrasonic beam is incidented. And the null zone caused by the interference of these two waves is appearing in the reflected field. The phase difference is changed as the surface condition altered, including surface roughness and layered structures. The normal-mode theory is used at this research to analyze the analytical model of the leaky surface wave in thin layered structures. In experiments, the measurements of the reflected field are proceeded by the scanning system, so as to analyze the phase difference between the reflected and leaky ultrasound and calculate the layer thickness by the phase difference. As a result of the surface roughness of the thin layers, the leakage is more serious when the ultrasound propagates with lower frequency. For the consideration of locating the null-zone in the reflected field, this research prefers using lower frequency as an initial frequency at the beginning of the testing, then increasing the frequency to achieve a better sensitive of the thickness.

Akustinių bangų ir šviesos – akustooptinė (AO) sąveika įgalina tirti akustinių bangų savybes ne tik kristalo paviršiuje, bet ir tūryje. Tai aktualu kuriant tūrinių bangų prietaisus įvairiems taikymams. Iki šiol yra atlikta keletas AO difrakcijos eksperimentų, kai sunertiniais keitikliais žadinamos tūrinės bangos, bet ne nuotėkio paviršinių akustinių bangų (PAB) spinduliuotė į tūrį. Kita vertus, AO sąveiką galima efektyviai panaudoti šviesos parametrų valdyme. Tūrinių bangų AO prietaisai – šviesos moduliatoriai, deflektoriai, derinami filtrai plačiai naudojami praktikoje. Šioje disertacijoje pateikiami anizotropinės šviesos difrakcijos nuotėkio paviršinių akustinių bangų spinduliuote į kristalo tūrį ZX-LiNbO3 ir YX-LiTaO3 eksperimentiniai rezultatai ir teorinis modelis. Tokio tipo sąveika įgalina suderinti sunertinių PAB keitiklių technologijos privalumus su didesniu šviesos sąveikos su tūrinėmis akustinėmis bangomis efektyvumu. Dėmesys mišraus valentingumo manganitams, turintiems perovskito kristalinę gardelę vis didėja dėl fazinio virsmo paramagnetikas – feromagnetikas Kiuri temperatūroje, milžiniškosios magnetovaržos efekto, didelės unikalių tarpusavyje susijusių savybių įvairovės ir potencialo įvairiuose taikymuose. Dėl stiprios Jahn-Teller tipo elektron-fononinės sąveikos akustiniai metodai yra perspektyvūs tiriant manganitus. Šioje disertacijoje pateikiami nuotėkio paviršinių akustinių bangų spinduliuotės į tūrį sklidimo dariniuose La0.67Sr0.33MnO3 plėvelė –... [toliau žr. visą tekstą] / Acoustic wave and light – acousto-optic (AO) interaction provides an efficient tool for probing the acoustic wave properties not only at a crystal surface but also at any point within its bulk. This is topical in the design of the bulk wave devices for various applications. Meanwhile, there have been a few investigations of AO diffraction by (interdigital transducer) IDT-generated bulk waves, but not of the diffraction due to the radiation from leaky surface acoustic waves (SAWs). On the other hand, AO interaction enables efficient control of light parameters. Bulk wave AO devices have found numerous applications as light modulators, deflectors, tunable filters. In this PhD thesis, the experimental investigation and theoretical model of anisotropic light diffraction by leaky SAW radiation into crystal bulk in ZX-LiNbO3 and YX-LiTaO3 are reported. This type of interaction allows one to combine benefits of the IDT technology with the enhanced interaction efficiency of bulk-wave-type interaction. Mixed-valence perovskite manganites were studied intensively in recent years due to the observed paramagnetic to ferromagnetic transition at Curie temperature, colossal magnetoresistance effect, a variety of unique properties and potential at various applications. Due to the strong Jahn-Teller electron-phonon coupling the acoustic technique is effective tool for investigations of manganites. In this PhD thesis, the experimental investigation of the leaky SAW radiation propagating in... [to full text]

Acoustic wave and light – acousto-optic (AO) interaction provides an efficient tool for probing the acoustic wave properties not only at a crystal surface but also at any point within its bulk. This is topical in the design of the bulk wave devices for various applications. Meanwhile, there have been a few investigations of AO diffraction by (interdigital transducer) IDT-generated bulk waves, but not of the diffraction due to the radiation from leaky surface acoustic waves (SAWs). On the other hand, AO interaction enables efficient control of light parameters. Bulk wave AO devices have found numerous applications as light modulators, deflectors, tunable filters. In this PhD thesis, the experimental investigation and theoretical model of anisotropic light diffraction by leaky SAW radiation into crystal bulk in ZX-LiNbO3 and YX-LiTaO3 are reported. This type of interaction allows one to combine benefits of the IDT technology with the enhanced interaction efficiency of bulk-wave-type interaction. Mixed-valence perovskite manganites were studied intensively in recent years due to the observed paramagnetic to ferromagnetic transition at Curie temperature, colossal magnetoresistance effect, a variety of unique properties and potential at various applications. Due to the strong Jahn-Teller electron-phonon coupling the acoustic technique is effective tool for investigations of manganites. In this PhD thesis, the experimental investigation of the leaky SAW radiation propagating... [to full text] / Akustinių bangų ir šviesos – akustooptinė (AO) sąveika įgalina tirti akustinių bangų savybes ne tik kristalo paviršiuje, bet ir tūryje. Tai aktualu kuriant tūrinių bangų prietaisus įvairiems taikymams. Iki šiol yra atlikta keletas AO difrakcijos eksperimentų, kai sunertiniais keitikliais žadinamos tūrinės bangos, bet ne nuotėkio paviršinių akustinių bangų (PAB) spinduliuotė į tūrį. Kita vertus, AO sąveiką galima efektyviai panaudoti šviesos parametrų valdyme. Tūrinių bangų AO prietaisai – šviesos moduliatoriai, deflektoriai, derinami filtrai plačiai naudojami praktikoje. Šioje disertacijoje pateikiami anizotropinės šviesos difrakcijos nuotėkio paviršinių akustinių bangų spinduliuote į kristalo tūrį ZX-LiNbO3 ir YX-LiTaO3 eksperimentiniai rezultatai ir teorinis modelis. Tokio tipo sąveika įgalina suderinti sunertinių PAB keitiklių technologijos privalumus su didesniu šviesos sąveikos su tūrinėmis akustinėmis bangomis efektyvumu. Dėmesys mišraus valentingumo manganitams, turintiems perovskito kristalinę gardelę vis didėja dėl fazinio virsmo paramagnetikas – feromagnetikas Kiuri temperatūroje, milžiniškosios magnetovaržos efekto, didelės unikalių tarpusavyje susijusių savybių įvairovės ir potencialo įvairiuose taikymuose. Dėl stiprios Jahn-Teller tipo elektron-fononinės sąveikos akustiniai metodai yra perspektyvūs tiriant manganitus. Šioje disertacijoje pateikiami nuotėkio paviršinių akustinių bangų spinduliuotės į tūrį sklidimo dariniuose La0.67Sr0.33MnO3 plėvelė –... [toliau žr. visą tekstą]

abstract: Articially engineered two-dimensional materials, which are widely known as metasurfaces, are employed as ground planes in various antenna applications. Due to their nature to exhibit desirable electromagnetic behavior, they are also used to design waveguiding structures, absorbers, frequency selective surfaces, angular-independent surfaces, etc. Metasurfaces usually consist of electrically small conductive planar patches arranged in a periodic array on a dielectric covered ground plane. Holographic Articial Impedance Surfaces (HAISs) are one such metasurfaces that are capable of forming a pencil beam in a desired direction, when excited with surface waves. HAISs are inhomogeneous surfaces that are designed by modulating its surface impedance. This surface impedance modulation creates a periodical discontinuity that enables a part of the surface waves to leak out into the free space leading to far-eld radia- tion. The surface impedance modulation is based on the holographic principle. This dissertation is concentrated on designing HAISs with Desired polarization for the pencil beam Enhanced bandwidth Frequency scanning Conformity to curved surfaces HAIS designs considered in this work include both one and two dimensional mod- ulations. All the designs and analyses are supported by mathematical models and HFSS simulations. / Dissertation/Thesis / Doctoral Dissertation Electrical Engineering 2017

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This thesis solves estimation and control problems in computational neuroscience, mathematically dealing with the first-passage times of diffusion stochastic processes. We first derive estimation algorithms for model parameters from first-passage time observations, and then we derive algorithms for the control of first-passage times. Finally, we solve an optimal design problem which combines elements of the first two: we ask how to elicit first-passage times such as to facilitate model estimation based on said first-passage observations. The main mathematical tools used are the Fokker-Planck partial differential equation for evolution of probability densities, the Hamilton-Jacobi-Bellman equation of optimal control and the adjoint optimization principle from optimal control theory. The focus is on developing computational schemes for the solution of the problems. The schemes are implemented and are tested for a wide range of parameters.

abstract: Impedance-modulated metasurfaces are compact artificially-engineered surfaces whose surface-impedance profile is modulated with a periodic function. These metasurfaces function as leaky-wave antennas (LWAs) that are capable of achieving high gains and narrow beamwidths with thin and light-weight structures. The surface-impedance modulation function for the desired radiation characteristics can be obtained using the holographic principle, whose application in antennas has been investigated extensively. On account of their radiation and physical characteristics, modulated metasurfaces can be employed in automotive radar, 5G, and imaging applications. Automotive radar applications might require the antennas to be flush-mounted on the vehicular bodies that can be curved. Hence, it is necessary to analyze and design conformal metasurface antennas. The surface-impedance modulation function is derived for cylindrically-curved metasurfaces, where the impedance modulation is along the cylinder axis. These metasurface antennas are referred to as axially-modulated cylindrical metasurface LWAs (AMCLWAs). The effect of curvature is modeled, the radiation characteristics are predicted analytically, and they are validated by simulations and measurements. Communication-based applications, like 5G and 6G, require the generation of multiple beams with polarization diversity, which can be achieved using a class of impedance-modulated metasurfaces referred to as polarization-diverse holographic metasurfaces (PDHMs). PDHMs can form, one at a time, a pencil beam in the desired direction with horizontal polarization, vertical polarization, left-hand circular polarization (LHCP), or right-hand circular polarization (RHCP). These metasurface antennas are analyzed, designed, measured, and improved to include the ability to frequency scan. In automotive radar and other imaging applications, the performance of metasurface antennas can be impacted by the formation of standing waves due to multiple reflections between the antenna and the target. The monostatic RCS of the metasurface antenna is reduced by modulating its surface impedance with a square wave, to avert multiple reflections. These square-wave-modulated metasurfaces are referred to as checkerboard metasurface LWAs, whose radiation and scattering characteristics, for normal incidence parallel polarization, are analyzed and measured. / Dissertation/Thesis / Doctoral Dissertation Electrical Engineering 2020