Variations in low-grade wood modification and stress lamination

Sitka spruce (Picea sitchensis) trees in UK forests are expected to yield nearly 30% more softwood than current levels in the coming decades. These are relatively fast-growing trees, yielding low-grade wood that is incompatible with standards for glue-based lamination. Alongside this forecasted increase, there is a major worldwide shift towards building taller and faster with massive laminated and engineered wood products, mainly as substitutes for steel and concrete. For making the best use of the expected increase in UK softwood and also to expand the scope of tall wood construction, alternative ways of working with low-grade wood are needed, along with developing new variations of existing techniques in processing and construction. This thesis examines two strategies: wood modification by impregnation and stress lamination. The former involves treating wood under pressure in a liquid solution. Once impregnated, the liquid is then solidified in-situ, grafting onto the wood to enhance its properties through direct molecular interactions in the cell wall. While wood treatments are usually done to increase durability, literature and preliminary small-scale testing suggest that impregnation can also lead to increases in stiffness and strength. Compared to wood modification, stress lamination is a relatively simple yet effective technique, and is useful for laminating wood without glue. Although widely used in timber bridges, stress lamination has found little to no application in buildings, primarily due to concerns regarding losses in prestress levels from creep and the moisture-related movement and shrinkage of wood. Scale models and testing emphasise the technique’s potential for both standard and bespoke structural elements for buildings. Full-scale detailing, construction, and testing of straight columns further establishes structural performance and feasibility. Test results from shearing five full-scale stress-laminated connections show performance beyond that of conventional mechanical fasteners. Twenty-five columns were also tested at full-scale, showing comparable buckling performance to Eurocode estimates for solid timber. Examples from literature and a new detail with overdried hardwood plates, tested during a six-month period, demonstrate that prestress losses can be mitigated to ensure long-term reliability in buildings. The full-scale testing performed in this thesis therefore highlights the usefulness, performance, and reliability of stress lamination with low-grade wood for multi-storey construction.UK Engineering and Physical Sciences Research Council (EPSRC) Cambridge Commonwealth Trust Ramboll Foundation Natural Sciences and Engineering Research Council of Canada (NSERC

Photonic low-cost sensors for in-line fluid monitoring. Design methodology

779 p.The paradigm of process monitoring has evolved in the last years, driven by a clear need for improving efficiency, quality and safety of processes and products. Sectors as manufacturing, energy, food and beverages, etc. are fostering the adoption of innovative methods for controlling their processes and products, in a non-destructive, in-place, reliable, fast, accurate and cost-efficient manner. Furthermore, the parameters requested by the industry for the quality assessment are evolving from basic magnitudes as pressures, temperatures, humidity, etc. to complete chemical and physical fingerprints of these products and processes. In this situation, techniques based on the UV/VIS/NIR light-matter interaction appear to be optimum candidates to face the request of the industry. Moreover, at this moment, when we are witnessing a technological revolution in the field of optoelectronic components, which are required for setting up these light-based analyzers.However, being able to integrate these optoelectronic components with the rest of subsystems (electronics, optics, mechanics, hydraulics, data processing, etc.) is not straightforward. The development of these multi-domain and heterogeneous sensor products meeting not just technological but also market objectives poses a considerable technical and organizational challenge for any company.In this context, a methodological hybrid and agile integration of photonic components within the rest of subsystems towards a sensor product development is presented as the main outcome of the thesis. The methodology has been validated in several industrial scenarios, being three of them included in this thesis, which covers from hydraulic fluid quality control to real-time monitoring of alcoholic beverage fermentation process

Imaging of Temperature Variations in the Near-Wall Region of an Optical Reciprocating Engine using Laser-Induced Fluorescence

Understanding engine heat transfer can enable the design of more efficient engines with advanced operational strategies that reduce net carbon emissions. However, accurate predictions of in-cylinder heat transfer processes require a significant investigation into the transient thermal boundary layer effects within the near-wall region (NWR). This work investigates the development of thermal stratification at two measurement locations near the cylinder head surface of an optical reciprocating engine using laser-induced fluorescence (LIF). Temperature images are obtained from high-speed toluene LIF measurements using the one-color detection technique, and the calibration procedure is based on predicted in-cylinder temperature from an engine simulation software (GT-Power). Precision uncertainty is assessed within a 1 x 1 mm2 calibration region, and found to be within ±2 K. First measurements examine temperature variations within a 20 x 12 mm2 field-of-view that includes the cylinder head and the piston top surfaces under motored operating conditions, while a second set of measurements examine temperature variations within an 8 x 6 mm2 field-of-view at the cylinder head surface under motored and fired operating conditions and at two different engine speeds. The near-wall temperature measurements of this work provide unique insights into the spatial and temporal temperature variations in the NWR of an optical reciprocating engine, which were enabled by a rigorous experimental effort and attentive post-processing steps to quantitatively process the LIF images to yield temperature fields. These measurements add to continuous effort to extend the fundamental understanding of near wall engine heat transfer, and aid in achieving a more comprehensive characterization of the NWR by complementing previously-collected near wall velocity measurements and a parallel effort in Large Eddy Simulations (LES) that focus on wall heat transfer. Future work should address improvements to the experimental methodology to better resolve the region within 0.5 mm from the surface, and perform simultaneous velocity field and surface temperature imaging to fully quantify turbulent heat fluxes, which are critical to understand heat transfer under transient high pressure, high-temperature conditions.PHDMechanical EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/162972/1/malzuabi_1.pd

R&D Proposal Development of Micro-Pattern Gas Detector Technologies

Development of advanced gas-avalanche detector technologies and associated electronic-readout systems for applications in basic and applied researc

Enhancement of the Properties of Polymer by using Carbon Nanotubes

The outstanding properties of carbon nanotubes (CNTs) have stimulated a large number of researches to explore the potential of using them as reinforcement in polymer composites. Although many studies have reported the enlighten improvement of the materials properties by using CNTs as reinforcement, there are no promising and optimal results have been concluded to date. This thesis aims at studying the mechanical properties on thermoset polymer, Epoxy, by employing a small amount of carbon nanotubes as reinforcement. Two different types of nanotube-based composites are prepared i.e. a raw single-walled carbon nanotube (SWNT) composites and a functionalized single-walled carbon nanotube (FSWNT) composite. Chemical functionalization on SWNTs with carboxyl functional group (COOH) aims at modifying the end caps of nanotubes, so to provide covalent bonding of SWNTs to the polymer matrix during manufacturing of composite systems. Different weight percentages (wt %) of each type of SWNTs are added into the composite system. Standard test methods are performed on these nanotube composite systems and satisfactory results were achieved when the weight percentages of both types of SWNTs increased. Through the comparison between two systems (raw SWNTs and FSWNTs), the FSWNT reinforced composite is found to provide a better improvement on the mechanical properties as compared with the SWNT reinforced system. The integrity of both composite systems is examined by using Scanning Electronic Microscopy (SEM). The SEM images of the composites indicated the derivation in wetting and bonding between the nanotubes (both SWNTs and FSWNTs) and epoxy resin, and the FSWNTs provide an eminent dispersion when compared with the SWNTs in the composite system. Moreover, thermal testings are employed to further investigate the interfacial interaction between the nanotubes and the polymer matrix. xiv Molecular Dynamics (MD) simulations are also carried out to investigate the structural change of a SWNT under different temperature-controlled manufacturing environments. Swivel of the SWNT was noticed as the temperature increased. Such alteration in structure form can provide physical interlocking between SWNT and its surrounding polymer system. Thus, its overall mechanical and thermal properties can be enhanced

Developing & tailoring multi-functional carbon foams for multi-field response

As technological advances occur, many conventional materials are incapable of providing the unique multi-functional characteristics demanded thus driving an accelerated focus to create new material systems such as carbon and graphite foams. The improvement of their mechanical stiffness and strength, and tailoring of thermal and electrical conductivities are two areas of multi-functionality with active interest and investment by researchers. The present research focuses on developing models to facilitate and assess multi-functional carbon foams in an effort to expand knowledge. The foundation of the models relies on a unique approach to finite element meshing which captures the morphology of carbon foams. The developed models also include ligament anisotropy and coatings to provide comprehensive information to guide processing researchers in their pursuit of tailorable performance. Several illustrations are undertaken at multiple scales to explore the response of multi-functional carbon foams under coupled field environments providing valuable insight for design engineers in emerging technologies. The illustrations highlight the importance of individual moduli in the anisotropic stiffness matrix as well as the impact of common processing defects when tailoring the bulk stiffness. Furthermore, complete coating coverage and quality interface conditions are critical when utilizing copper to improve thermal and electrical conductivity of carbon foams

A Pseudo Non-Cartesian Pulse Sequence For Hyperpolarized Xenon-129 Gas MRI of Rodent Lungs At Low Magnetic Field Strength

Background: Early diagnosis of radiation-induced lung injury (RILI) following radiation therapy is critical for prevention of permanent lung damage. Pulmonary imaging using magnetic resonance imaging (MRI) of the apparent diffusion coefficient (ADC) of hyperpolarized xenon (129Xe) gas shows promise for early measurement of RILI. Methods: An ultra-short echo time imaging sequence based on a pseudo-Cartesian k-space trajectory, known as Sectoral, is implemented at low magnetic field (0.07 T) for efficient use of the non-renewable magnetization of hyperpolarized 129Xe gas. A pilot study was performed to demonstrate the feasibility of ADC mapping using the Sectoral sequence on healthy and 2-weeks post irradiated rats. Results: A significant (p \u3c 0.05) correlation between mean ADC values from Sectoral ADC maps and the mean linear intercept (Lm), as a measure of interalveolar wall distance, from histological sections of the lungs was observed (p = 0.0061) and a significant (p \u3c 0.05) separation between healthy and irradiated lungs was observed with full width at half maximum ADC (p = 0.0317). Conclusion: Sectoral MRI with 129Xe is feasible in rats. Decreases in ADC were measured following lung irradiations which correlate with Lm

Classification of breast malignancy using optimised advanced diffusion-weighted imaging : and surgical planning for breast tumour resection using MR-guided focused ultrasound

Intravoxel Incoherent Motion Imaging (IVIM) is a non-invasive MR-imaging technique that enables the measurement of cellularity and vascularity using diffusion-weighted (DW)-imaging. IVIM has been applied to various cancer types including breast cancer, and is becoming more popular but lacks standardisation. The quantitative parameters; diffusion, D, perfusion fraction, f, and pseudo micro capillary diffusion, D* are thought to be correlated with tumour physiognomies such as proliferation, angiogenesis and heterogeneity.In Part 1 of this thesis, an optimised clinical b-value protocol is produced using a robust statistical method. This optimised protocol and various fitting methodologies are investigated in healthy volunteers, and then the most precise approach is applied in a clinical trial in patients following diagnosis of breast cancer, before treatment, to correlate IVIM parameters with breast cancer grade, histological type and molecular subtype with statistically significant results supporting IVIM’s potential as a non-invasive biomarker for malignancy. Monte Carlo simulations support this clinical application, where real data mean squared errors due to SNR limitations lie within simulated errors. A computed DW-imaging program is also presented to produce better quality images than acquired high b-value images as an adjunct to the optimised IVIM protocol.In Part 2 of this thesis, MR-guided Focused Ultrasound (MRgFUS) is explored as a means to create a pre-surgical template of thermally induced palpable markers to enable a surgeon to resect occult lesions and potentially reduce positive tumour margin status and local recurrence after breast conserving surgery. A surrogate animal model with pseudo lesion is presented, as well as a clinical tool to plan spot markers around a lesion as seen on MRI