Despite the on-going intensity of research in the field of protective structural design, one topic that has been largely ignored in the literature is the effect of high strain rates on the bond between reinforcing steel and the surrounding concrete. Therefore, a comprehensive research program was undertaken to establish the effect of high strain rates on reinforced concrete bond. The experimental research consisted of the construction and testing of fourteen flexural beam-end bond specimens and twenty-five lap-spliced reinforced concrete beams. The physical and material properties of the specimens were selected based on a range of design parameters known to significantly influence bond strength. In order to establish a baseline for comparison, approximately half of the total number of specimens were subjected to static testing, while the remainder were subjected to dynamic loading generated using a shock tube. The strain rates generated using the shock tube were consistent with those obtained for mid- and far-field explosive detonation. Results of the beam-end and lap splice beam tests showed that the flexural behaviour of reinforced concrete was significantly stronger and stiffer when subjected to dynamic loading. Furthermore, the high strain rate bond strength was always greater than the corresponding low strain rate values, yielding an average dynamic increase factor (DIF) applied to ultimate bond strength of 1.28. Analysis of the low and high strain rate test results led to the development of empirical expressions describing the observed strain rate sensitivity of reinforced concrete bond for spliced and developed bars with and without transverse reinforcement. The predictive accuracy of the proposed DIF expressions was assessed against the experimental results and data from the literature. It was found that the dynamic bond strength of reinforced concrete can be predicted with reasonably good accuracy and that the proposed DIF expressions can be used for analysis and design of protective structures. An analytical method was also developed to predict the flexural load-deformation behaviour of reinforced concrete members containing tension lap splices. The analysis incorporated the effect of reinforcement slip through the use of pseudo-material stress-strain relationships, in addition to giving consideration to the effect of high strain rates on bond-slip characteristics and on the material properties of concrete and steel. A comparison of the analytical predictions with experimental data demonstrated that the proposed analysis technique can reasonably predict the flexural response of beams with tension lap splices. The results also demonstrated that the model is equally applicable for use at low- and high-strain rates, such as those generated during blast and impact.

SSDs are now commonplace in all types of computing from consumer laptops to enterprise storage systems. However, most of those SSDs would not survive in environments with extreme temperatures or high shock and vibration such as found in embedded and military systems. The problems in this space are more than just mechanical; they involve all aspects of the design including electrical and even firmware. A combination of all three engineering disciplines is needed to provide a robust ruggedized SSD product.

A recent development for the numerical modelling of material discontinuities is presented in this thesis. The concepts considered here are founded on the idea that for each physical variable (e.g. temperature, enthalpy, etc.) there exists an associated non-physical variable. The numerical technique presented here that utilises non-physical variables is called the non-physical finite element method (NPFEM). The NPFEM involves the replacement of a discontinuous physical field with a limiting-continuous non-physical field (i.e. abstract mathematical object) which is continuous over the domain but has a source-like behaviour at the place of a discontinuity. Non-physical variables are rigorously defined in the thesis and are related to their physical counterparts by means of transport equations. As a consequence of the coupling of physical and non-physical variables, equivalent forms of transport equations arise. However, as a consequence of limiting continuity the adopted approach permits the representation of non-physical variables by means of a polynomial basis standard to the continuous Galerkin finite element method (CGFEM).The non-physical method was originally devised for the modelling of material discontinuities in solidification problems involving a strong discontinuity in enthalpy and a weak discontinuity in temperature. The work presented here extends previous works by providing a general framework for the non-physical method to facilitate modelling of strong material discontinuities in all the state variables along with velocity arising with material discontinuities. The approach is founded on the integral transport form of the governing conservation laws. The advantage of the non-physical methodology is that it permits the precise annihilation of discontinuous behaviour in the governing finite element equations by means of a distribution like source term at the discontinuity location. Different case studies of single and multiple stationary and transient 1-D shock waves in fluids and solids are undertaken to show the accuracy, flexibility and robustness of the non-physical finite element method. Also presented as part of the work is a newly developed analytical model for the 1-D high velocity crushing of the cellular bars.

Les étoiles Miras sont des étoiles froides et évoluées (étoiles AGB), caractérisées par une variation de luminosité régulière et de longue période liée à une pulsation radiale. Cela se traduit par une atmosphère froide, étendue et faiblement liée gravitationnellement. Dans le spectre de ces étoiles, la détection variable d'émissions intenses dans les raies de Balmer de l'hydrogène est usuellement reliée à la propagation périodique d'une onde de choc radiative hypersonique dans l'atmosphère. Mon travail de thèse a eu d'abord pour objectif de confirmer l'existence d'une forte signature de polarisation linéaire accompagnant ces émissions, d'origine inconnue et déjà observée auparavant, et de caractériser son évolution temporelle. Je me base sur un suivi spectropolarimétrique inédit et effectué dans le cadre de ma thèse avec l'instrument NARVAL pour plusieurs Miras afin d'établir cette caractérisation. Ces suivis ont été réalisé sur tous les paramètres de Stokes (polarisation linéaire et circulaire) et surtout à des phases autour du maximum de luminosité.Un résultat majeur de ces observations est la détection systématique de signatures polarisées (polarisation surtout linéaire mais aussi parfois circulaire) liées aux émissions en intensité dans les raies de Balmer. L'utilisation d'un code de simulation d'atmosphère dynamique m'a permis de confirmer le lien entre une onde de choc et la présence d'émission dans ces raies, chose qui n'avait jamais été montrée par un modèle jusque là. Ces éléments me font affirmer que le mécanisme de polarisation est intrinsèque à l'onde de choc. La discussion sur l'origine de cette polarisation comporte deux grands axes : l'asymétrie globale de l'onde de choc amenant à une polarisation nette du rayonnement et la production locale dans le front du choc d'un champ magnétique responsable d'une polarisation par impact dans la zone de production des photons Balmer, c'est-à-dire le sillage du choc. D'autre part, j'invoque la possibilité d'une instabilité de Parker comme deuxième facteur de polarisation par impact et je discute le rôle potentiel de l'effet Hanle. / Mira stars are cool and evolved stars (AGB stars), characterized by a regular luminosity variation and a long period linked to a radial pulsation. All this imply a cool and extended atmosphere which is weakly linked by gravity. In the spectra of those stars, the variable detection of intense emissions in the Balmer lines of hydrogen are usually linked to the periodical propagation of a hypersonic radiative shock wave in the atmosphere. My thesis work's first objective was to confirm the existence of a strong polarimetric signature accompanying those emissions, whose origin is still unknown and already observed before, and to characterize its evolution through time. I rely on a novel spectropolarimetric survey, done in the framework of my thesis with the NARVAL instrument for several Mira stars in order to establish this characterization. Those surveys were done on all Stokes parameters (linear and circular polarization) and mainly during phases around the maximum of luminosity.A major result of these observations is the systematic detection of polarized signatures (mainly linear polarization but also circular sometimes) linked to the emissions in intensity in the Balmer lines. The use of a dynamical atmosphere simulation code allowed me to confirm the link between a shock wave and the presence of emissions in those lines. Such a result has never been been produced by a model until now. These elements make me state that the polarization mechanism is intrinsic to the shock wave. The discussion on the origin of such polarization consists of two main axes : the global asymmetry of the shock wave leading to a net polarization of the radiation and the local production in the shock's front of a magnetic field responsible for an impact polarization in the area of production of Balmer photons, namely the shock's wake. Besides that, I mention the possibility of a Parker instability as a second factor of impact polarization and I discuss the potential role of the Hanle effect.

Publicación a texto completo no autorizada por el autor / Determina los factores asociados condicionantes de insuficiencia renal en pacientes con sepsis severa y shock séptico de la unidad de cuidados intensivos (UCI) del Hospital Central de la Fuerza Aérea Peruana. La investigación es de diseño longitudinal, comparativo, observacional y retrospectivo. La edad en el grupo de pacientes sépticos con IRA es 67 años y en el grupo sin IRA, 62 años. El peso promedio marca 67 kg en ambos grupos. La mitad de los pacientes sépticos con IRA, son hombres y en los pacientes sépticos sin IRA son 41,7%. La hipertensión arterial (HTA) se presenta como antecedente patológico en los pacientes sépticos con y sin IRA con 46,9% y 33,3% respectivamente. El valor del PSI en los pacientes sépticos con IRA es 0,7 y 1 en aquéllos sin IRA. El 40,6% de los pacientes sépticos que presentan IRA utilizan nefrotóxicos. El 59,4% de los pacientes sépticos con IRA utilizan ventilación mecánica y 41,7% en los pacientes sépticos sin IRA. El veinticinco por ciento de los pacientes sépticos con IRA están en diálisis. Se presenta oliguria en el 87,5% de los pacientes sépticos con IRA. La hipotensión se presenta en el 78,1% de los pacientes sépticos con IRA. La ictericia se presenta en el 28,1% de los pacientes sépticos con IRA. Se utiliza inotrópicos en el 65,6% pacientes sépticos con IRA y 25% en los pacientes sépticos sin IRA. La escala RIFLE en la categoría de injuria ocurre en el 34,1 y 15% de la población séptica con IRA y sin IRA, respectivamente cada uno. El foco en los pacientes sépticos con IRA proceden del aparato respiratorio y abdominal con 40.6% para ambos. Concluye que los factores asociados son el uso de ventilación mecánica e inotrópica, la presencia de oliguria, hipotensión e ictericia. / Tesis de segunda especialidad

Titanium dioxide and aluminum oxide are conventional materials used in heterogeneous catalysis as catalyst support. The widely used crystalline phase of both supports is the metastable phase (anatase and γ-Al$_2$O$_3$) in which they possess a higher specific surface area compared to the thermodynamically stable phase (rutile and α-Al$_2$O$_3$). However, these phases have better thermal and mechanical stability than anatase and γ-Al$_2$O$_3$. A novel method to induce phase transformation and structural modification of crystalline materials is by applying shock waves. This study aims to experimentally investigate the effects of shock wave treatment on titania and alumina. A pressure-driven shock tube was used in this work to generate the shock waves. Two sets of experiments were carried out for TiO$_2$ and one for Al$_2$O$_3$. Titania samples were prepared in the form of pellets for the first set. Titania and alumina samples were maintained as powder for the second set of experiments. For titania, twenty shocks were applied at nominal temperature and pressure of ~ 1772 K and 23.3 bar in the first set of experiments, while thirty shocks of ~ 1572 K and 66 bar were applied in the second set of experiments. For alumina, twenty shock loadings were applied at the same conditions used for the second set of titania. Characterization techniques, such as XRD, Raman spectroscopy, TEM, SEM, XPS, and N$_2$ physisorption were employed on treated samples in order to understand the effects of shock wave treatment. Partial phase transformation was observed in shock treated TiO2 from Raman spectra and TEM images. Crystallite size reduction was observed in the first set of experiments, while increase in defects was observed by the enhanced Ti$^{+3}$ in XPS spectra in both sets of experiments. Partial phase transformation was also observed in shock treated Al$_2$O$_3$, when mixed with CNF (carbon nanofibers), from XRD patterns and confirmed with XPS. For alumina, TEM and SEM images showed the smallest particles in contact with carbon fibers, while the biggest particles exhibited agglomeration. Physisorption experiments showed a decrease of 40% in surface area and pore collapse.

The theoretical part of this thesis focus on the description of the piezoelectric accelerometers and their use for the impact measurements. It also characterizes the construction and the calibration process of the impact hammers with the use of the piezoelectric accelerometers. The practical part describes the place of calibration with the calibration tools, identifies the source of the oscillations on the output signal of the accelerometer and suggests its compensation. Part of the thesis is a service program for the impact measurement, analysis and the impact hammer calibration. Thesis also describes the methodology of the calibration and quantifies the measurement uncertainty.

This diploma thesis deals with the landing gear design of the small two-seat aircraft. The introduction focuses on the conceptual gear design and shock absorber computational dynamic characteristic model. The practical part is focused on the landing gear construction according to the selected parameters based on the conceptual and computational model. The diploma thesis ends with strength calculations and production documentation.

Future thrusts for gasoline engine development can be broadly summarized into two categories: (i) efficiency improvements in conventional spark ignition engines, and (ii) development of advance compression ignition (ACI) concepts. Efficiency improvements in conventional spark ignition engines requires downsizing (and turbocharging) which may be achieved by using high octane gasolines, whereas, low octane gasolines fuels are anticipated for ACI concepts. The current work provides the essential combustion kinetic data, targeting both thrusts, that is needed to develop high fidelity gasoline surrogate mechanisms and surrogate complexity guidelines. Ignition delay times of a wide range of certified gasolines and surrogates are reported here. These measurements were performed in shock tubes and rapid compression machines over a wide range of experimental conditions (650 – 1250 K, 10 – 40 bar) relevant to internal combustion engines. Using the measured the data and chemical kinetic analyses, the surrogate complexity requirements for these gasolines in homogeneous environments are specified. For the discussions presented here, gasolines are classified into three categories: (i) Low octane gasolines including Saudi Aramco’s light naphtha fuel (anti-knock index, AKI = (RON + MON)/2 = 64; Sensitivity (S) = RON – MON = 1), certified FACE (Fuels for Advanced Combustion Engines) gasoline I and J (AKI ~ 70, S = 0.7 and 3 respectively), and their Primary Reference Fuels (PRF, mixtures of n-heptane and iso-octane) and multi-component surrogates. (ii) Mid octane gasolines including FACE A and C (AKI ~ 84, S ~ 0 and 1 respectively) and their PRF surrogates. Laser absorption measurements of intermediate and product species formed during gasoline/surrogate oxidation are also reported. (iii) A wide range of n-heptane/iso-octane/toluene (TPRF) blends to adequately represent the octane and sensitivity requirements of high octane gasolines including FACE gasoline F and G (AKI ~ 91, S = 5.6 and 11 respectively) and certified Haltermann (AKI ~ 87, S = 7.6) and Coryton (AKI ~ 92, S = 10.9) gasolines. To assess conditions where shock tubes may not be ideal devices for ignition delay measurements, this work also presents a detailed discussion on shock tube pre-ignition affected ignition data and the ignition regimes in homogeneous environments. The shock tube studies on pre-ignition and associated bulk ignition advance may help engines research community understand and control super-knock events.

Retaining walls (RW) are among the most common geotechnical structures. They have been widely used in railways, bridges (e.g. bridges abutment), buildings, hydraulic and harbor engineering. Once built, the RW can be exposed to dynamic loads, such as those produced by earthquakes, machines, vehicles and explosions. They must remain operational in aftermath of the natural or human-induced dynamic events. Hence, the understanding of the geotechnical response of RW to these dynamic loads is critical for the safe design of several civil engineering structures such as railways, highways, bridges, and buildings. Although fairly reliable methods have been developed for assessing and predicting the response of RW to dynamic loads induced by earthquakes, there is very little information to guide engineers in the design of RW that are exposed to surface explosions (surface blast loadings). These methods for assessing RW response to earthquake loads cannot directly be applied to the design of RW subjected to surface blast loads. Indeed, blast loads are short duration dynamic loads and their durations are very much shorter than those of earthquakes. The predominant frequencies of a blast wave are usually 2-3 orders of magnitudes higher than those of earthquake wave, and the same can be said for blast wave acceleration as compared to the peak acceleration that results from an earthquake. Thus, RW response under blast loading could be significantly different from that under a loading with much longer duration such as an earthquake. There is a need to increase our understanding of the response of RW to surface explosion loadings since there is a significant increase of terrorist threat on important buildings and some lifeline infrastructures. Transportation structures (bridges, highway, and railway) are unquestionably being regarded as potential targets for terrorist attacks. The purpose of this PhD research is to investigate the geotechnical response of reinforced concrete retaining wall (RCRW) with sand as a backfill material to surface blast loads. The soil-RW model was subjected to a simulated blast load using a shock tube. The influence of the backfill relative density, backfill saturation, blast load intensity, and live load surcharge on the behaviour of RCRW with sand backfill was studied. The dimensions of the stem and heel of the retaining wall in this study were 650 mm (height) x 500 mm (width) x 60 mm (thickness) and 400 mm (width) x 500 mm (length) x 60 mm (thickness), respectively. Soil-RW model was placed inside a wooden box. The overall height of the box was 1565 mm. The retained backfill extended behind the wall for 1300 mm. Based on the results, it is found that the maximum dynamic earth pressures were recorded at a time greater than the positive phase duration regardless of the backfill condition. The total earth pressure distribution along the height of the wall showed that the magnitude of total earth pressure for loose and medium backfill at the mid-height of the wall slightly exceeded the dense backfill. In addition, the lateral earth pressures increased with the increase in the blast load intensities. On the other hand, under the same load conditions, an increase in the wall movement was noticed in loose backfill, and a translation response mode was evident in this condition. The mobilized passive resistance of the RW backfill induced by blast load was used to determine the force-displacement relationship. Finally, the susceptibility of the RW with saturated dense sand to liquefaction was examined, and it was ascertained that liquefaction was not triggered when the RW was subjected to a blast load of 50 kPa. The results and findings of this PhD research will provide valuable information that can be used to evaluate the vulnerability of transportation structures to surface blast events as well as to develop guidance for their design.