An experimental program was conducted to investigate the strength and deformations of deep beams reinforced with Carbon Fibre Reinforced Polymer (CFRP) longitudinal and transverse reinforcement. Two groups of beams were tested, with each group comprising three beams. Two of the three beams in each group were reinforced with CFRP bars while the third beam was reinforced with conventional rebars and the latter beam was used as a control specimen. Beams in group 1 had span-to-depth ratio of one, while those in group 2 had a span-to-depth ratio of two. Beams in both groups had height of 900 mm and width of 250 mm. All the beams were simply supported and were tested in four-point bending with the point loads applied at one-third of the span. The test results revealed no significant difference between the behavior of the FRP reinforced beams and the companion control beams. On the other hand due to lack of hooks at the ends of the CFRP bars, and the loss of bond between the CFRP fibres and the sand grains on the surface of the bar, the failure in the CFRP reinforced beams was caused by the loss of anchorage while in the steel reinforced beams, the failure was initiated by the yielding of the longitudinal steel, followed by the crushing of the horizontal compression strut, but the nodal zones did not fail in any of the beams. Consequently, it was concluded that CFRP reinforced deep beams could be designed using the current CSA method for conventional steel reinforced concrete deep beams, provided the anchorage or bond strength of FRP bars could be properly determined. The existing nodal efficiency factors for the CCC nodal zones, as given in the CSA A23.3. standard, could be applied to CFRP reinforced beams while the corresponding factor for the CCT zone may be conservatively assumed to be 0.68. Finally, despite the linear elastic behavior of CFRP reinforcement, deep beams reinforced with CFRP bars could be designed using strut and tie models. / Thesis / Master of Applied Science (MASc)

Focused Ion Beam (FIB) technology is a versatile tool that can be applied in many fields to great effect, including semiconductor device prototyping, Transmission Electron Microscopy (TEM) sample preparation, and nanoscale tomography. Developments in FIB technology, including the availability of alternative ion sources and improvements in automation capacity, make FIB an increasingly attractive option for many tasks. In this thesis, FIB systems are applied to photonic device fabrication and modification, semiconductor reverse engineering, and the production of structures for the study of nanoscale radiative heat transfer. Optical facets on silicon nitride waveguides were produced with plasma FIB (PFIB) and showed an improvement of 3 ± 0.9 dB over reactive ion etched (RIE) facets. This process was then automated and is capable of producing a facet every 30 seconds with minimal oversight. PFIB was then employed to develop a method for achieving local backside circuit access for circuit editing, creating local trenches with flat bases of 200 x 200 μm. Gas assisted etching using xenon difluoride was then used in order to accelerate the etch process. Finally, several varieties of nanogap structure were fabricated on devices capable of sustaining temperature gradients, achieving a minimum gap size with PFIB of 60 nm. / Thesis / Master of Applied Science (MASc)

Since the first detection of a Gravitational Wave, the LIGO-Virgo Collaboration has worked to improve the sensitivity of their detectors. This continuous effort paid off in the last scientific run, in which the collaboration detected an average of one gravitational wave per week and collected 74 candidates in less than one year. This result was also possible due to the Frequency Independent Squeezing (FIS) implementation, which improved the Virgo detection range for the coalescence between two Binary Neutron Start (BNS) of 5-8\%. However, this incredible result was dramatically limited by different technical issues, among which the most dangerous was the mismatch between the squeezed vacuum beam and the resonance mode of the cavities. The mismatch can be modelled as a simple optical loss in the first approximation. If the beam shape of squeezed vacuum does not match the resonance mode, part of its amplitude is lost and replaced with the incoherent vacuum. However, this modelisation is valid only in simple setups, e.g. if we study the effect inside a single resonance cavity or the transmission of a mode cleaner. In the case of a more complicated system, such as a gravitational wave interferometer, the squeezed vacuum amplitude rejected by the mismatch still travels inside the optical setup. This component accumulates an extra defined by the characteristics of the mismatch, and it can recouple into the main beam reducing the effect of the quantum noise reduction technique. This issue will become more critical in the implementation of the Frequency Dependent Squeezing. This technique is an upgrade of the Frequency Independent Squeezing one. The new setup will increase the complexity of the squeezed beam path. The characterisation of this degradation mechanism requires a dedicated wavefront sensing technique. In fact, the simpler approach based on studying the resonance peak of the cavity is not enough. This method can only estimate the total amount of the optical loss generated by the mismatch, but it cannot characterise the phase shift generated by the decoupling. Without this information is impossible to estimate how the mismatched squeezed vacuum is recoupled into the main beam, and this limits the possibility to foreseen the degradation of the Quantum Noise Reduction technique. For this reason, the Padova-Trento Group studied different techniques for characterising Mode Matching. In particular, we proposed implementing the Mode Converter technique developed by Syracuse University. This technique can fully characterise the mismatch of a spherical beam, and it can be the first approach to monitoring the mismatch. However, this method is not enough for the Frequency Dependent Squeezer source since it cannot detect the mismatch generated by the astigmatism of the incoming beam. In fact, the Frequency Dependent Squeezer Source case uses off-axis reflective telescopes to reduce the power losses generated by transmissive optics. This setup used curved mirrors that induce small astigmatic aberrations as a function of the beam incident angle. These aberrations are present by design, and the standard Mode Converter Technique will not detect them. To overcome this issue, I proposed an upgrade of the Mode Converter technique, which can extend the detection to this kind of aberration.

yes / This paper presents a compact-size, low-cost smart antenna with electronically switchable radiation patterns, and reconfigurable polarizations. This antenna can be dynamically switched to realize three different polarizations including two orthogonal linear polarizations and one diagonally linear polarization. By closely placing several electronically reconfigurable parasitic elements around the driven antenna, the beam switching can be achieved in any of the three polarization states. In this design, a polarization reconfigurable square patch antenna with a simple feeding network is used as the driven element. The parasitic element is composed of a printed dipole with a PIN diode. Using different combinations of PIN diode ON/OFF states, the radiation pattern can be switched toward different directions to cover an angle range of 0◦ to 360◦ in the azimuth plane. The concept is confirmed by a series of measurements. This smart antenna has the advantages of compact size, low cost, low power consumption, reconfigurable polarizations, and beams.

Yes / A novel beam-forming module based on Wilkinson power divider technology, including attenuators and phase shifter chips is designed, fabricated and evaluated to be incorporated in a Relay Station connecting it with the Base Station under a 4G network. The proposed module is a 1:8 port circuit, utilizing two substrates, providing approximately 700 MHz bandwidth over 3.5 GHz frequency band and less than −20 dB transmission line coupling. Moreover an external control unit that feeds the beam-forming module with code-words that define the proper amplitude/phase of the excitation currents is established and described. The presented module is connected to a planar array and tested for two beam-forming scenarios, providing satisfactory radiation patterns.

Yes / This paper presents a planar multi-circular loop antenna with a wide impedance bandwidth for next generation mm-wave systems. The proposed antenna comprises three circular rings with a partial ground plane with a square slot. The resonating structure is designed on a 0.254 mm thin RO5880 substrate with a relative permittivity of 2.3. The single element of the proposed design showed a resonance response from 26.5 to 41 GHz, with a peak gain of 4 dBi and radiation efficiency of 96%. The proposed multicircular ring antenna element is transformed into a four-element array system. The array size is kept at 18.25 × 12.5 × 0.254 mm3 with a peak gain of 11 dBi. The antenna array is fabricated and measured using the in-house facility. The simulated and measured results are well agreed upon and are found to be suitable for mm-wave communication systems.

The charged pion production reactions d(gamma,pi⁺n), d(gamma,pi^-p), HD(gamma,pi⁺n)X were studied using linearly polarized gamma-rays with energies in the range from 260 MeV to 370 MeV at the Laser Electron Gamma Source (LEGS). A solid HD target was used in this experiment for the first time. The beam asymmetry data for the d(gamma,pi^-p) reaction significantly add to the previously available data. This gives new input to multipole analysis of pion production. A slight deviation from the beam asymmetry predicted for the free neutron is observed. The cross sections in the d(gamma,pi^-p) channel agree with previous measurements. / Ph. D.

In this thesis we analyze the buckling behavior of an infinitely long, thin, uniform, inextensible, elastic plate that has a steady current flowing along its length. We are concerned with the derivation of the nonlinear equations of motion using nonlinear continuum mechanics, and subsequent analysis of the buckling behavior of the plate under electromagnetic self-forces. In particular, we concentrate on how the body-forces that result from the applied current determine the buckled configurations. We derive both analytical and numerical results, and in the process develop a novel boundary value problem solver for integro-differential equations in addition to a predictor-corrector algorithm to continue solutions with respect to the control parameters. We take a relatively complex problem in magneto-solid mechanics and elasticity theory and form a realistic model that sheds light on the bifurcation and buckling behavior resulting from the electromagnetic-field- induced self-forces that are derived in their full, exact form using Biot-Savart Law. / Ph. D.

The behavior and strength of welded shear studs are subjects of ongoing study. In recent years, research has shown that the American Institute of Steel Construction (AISC) specification equations for shear stud strength are unconservative for studs placed in deck with ribs transverse to the steel beam. Twenty-four solid slab push-out tests, 93 composite slab push-out tests, and bare stud tests were performed to study the effects on stud strength of friction, normal load, position of studs in the ribs of steel deck, concrete strength, and stud properties. Stud diameters ranged from 3/8 in. to 7/8 in., deck heights ranged from 2 in. to 6 in., and both single and pairs of studs were tested. The push-out test results from this study were combined with other studies to propose a new stud strength prediction model. Three new beam tests were performed to study the effect of the stud position in the ribs of the steel deck. The results of these tests, along with 61 other beam tests, were used to verify the new stud strength prediction model. A reliability study was performed to determine resistance factors for stud strength and beam strength. / Ph. D.

An efficient beam-column approach, using an improved step-by-step numerical method, is developed in the current research for studying the ultimate strength problems of stiffened panels with two load cases: 1) under longitudinal compression, and 2) under transverse compression. Chapter 2 presents an improved step-by-step numerical integration procedure based on (Chen and Liu, 1987) to calculate the ultimate strength of a beam-column under axial compression, end moments, lateral loads, and combined loads. A special procedure for three-span beam-columns is also developed with a special attention to usability for stiffened panels. A software package, ULTBEAM, is developed as an implementation of this method. The comparison of ULTBEAM with the commercial finite element package ABAQUS shows very good agreement. The improved beam-column method is first applied for the ultimate strength analysis of stiffened panel under longitudinal compression. The fine mesh elasto-plastic finite element ultimate strength analyses are carried out with 107 three-bay stiffened panels, covering a wide range of panel length, plate thickness, and stiffener sizes and proportions. The FE results show that the three-bay simply supported model is sufficiently general to apply to any panel with three or more bays. The FE results are then used to obtain a simple formula that corrects the beam-column result and gives good agreement for panel ultimate strength for all of the 107 panels. The formula is extremely simple, involving only one parameter: the product λΠorth2. Chapter 4 compares the predictions of the new beam-column formula and the orthotropic-based methods with the FE solutions for all 107 panels. It shows that the orthotropic plate theory cannot model the "crossover" panels adequately, whereas the beam-column method can predict the ultimate strength well for all of the 107 panels, including the "crossover" panels. The beam-column method is then applied for the ultimate strength analysis of stiffened panel under transverse compression, with or without pressure. The method is based on a further extension of the nonlinear beam-column theory presented in Chapter 2, and application of it to a continuous plate strip model to calculate the ultimate strength of subpanels. This method is evaluated by comparing the results with those obtained using ABAQUS, for several typical ship panels under various pressures. / Ph. D.