• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 109
  • 66
  • 13
  • 13
  • 9
  • 8
  • 8
  • 8
  • 4
  • 1
  • 1
  • 1
  • 1
  • Tagged with
  • 286
  • 40
  • 30
  • 30
  • 22
  • 19
  • 17
  • 16
  • 16
  • 15
  • 15
  • 15
  • 14
  • 14
  • 14
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
61

Institutionalizing eugenics: class, gender and education in Nova Scotia's response to the "feeble-minded", 1890-1931

2015 January 1900 (has links)
Between 1890 and 1927 hundreds of Nova Scotian children and adults were identified as either feeble-minded or mentally deficient through investigations conducted by physicians and philanthropists in the province. The earliest of these studies were not commissioned by the provincial government but instead reflected the middle-class internalization of the eugenic discourse. Reformers, drawn often from medical, religious, educational, and philanthropic vocations, sought with ever-increasing alacrity to respond to perceived social problems, such as poverty, prostitution, venereal disease, and alcoholism, with a scientific solution. The scientific solution that they embraced was eugenics. Eugenic ideology and programs rose to popularity in Europe and North America at the end of the nineteenth and beginning of the twentieth century. Driven by social anxiety and the medicalization of reproduction, eugenic theory expressed the concerns of the middle classes that those they deemed less fit on the basis of socio-economic class, education or heredity, were reproducing at a higher rate than the ‘desirable’ segments of the population. The application of eugenic theory was shaped by cultural assumptions about gender, class and race which resulted in the same principles finding different expression in different areas across the globe. This dissertation seeks to understand how local circumstances shaped the Nova Scotian understanding of eugenics and its application. It examines the manner in which Nova Scotian physicians and philanthropists, with strong ties to both New England and Britain, participated in the transnational eugenic discourse through both professional and popular publications and organizations. Overall it argues that the expression of eugenics in Nova Scotia culminated in legislation that enforced the inspection, segregation and institutionalization of individuals who were assessed as feeble-minded. In doing so it also calls attention to the need to recognize outcomes other than sexual sterilization as legitimate expressions of eugenic policy. Subsequently the influential role played by regional circumstances in shaping what was considered an acceptable eugenic outcome as well as how eugenic policy was sought and implemented is examined. In investigating what reformers understood to be eugenic, and conversely what they considered dysgenic, a complex discourse surrounding the health of populations and reliant on ideas of gender, race, and class is revealed.
62

Automated Validation of User Equipment Connection States

Qudus, Abdul January 2014 (has links)
Telecom today has become an essence of life. Everywhere we see people using their smart phones for calling, checking email or accessing internet. To handle all these kinds of services without any intrusion is a very challenging task. This study deals with software testing which helps to ensure the quality of service to the end user. Software testing is an essential part in the software development process. Software development for telecom domain might not look as safety critical as of an airplane or nuclear reactor but it is arguably more complex. The main focus of this study is to provide automation to the unit testing of different types of radio connections that can be assigned to the end user based on the requested service and capacity of the 3G network. This research is sponsored by Ericsson to improve the testing of User Equipment Radio Connection Handling system that controls multiple possible radio connection configurations. This research attempts to identify and test all possible transitions between radio connection states. This will improve the existing manual state testing system, where changes in connection states cause dramatic impacts on test fixtures. As a solution, an automatic test case executor is proposed that generates possible transitions, which are later executed and verified automatically.
63

Explosion pour certaines équations Hamiltoniennes / Blow up for some Hamiltonian equations

Godet, Nicolas 03 December 2012 (has links)
Cette thèse porte sur l'étude des phénomènes d'explosion pour certaines équations aux dérivées partielles dispersives et plus particulièrement pour l'équation de Schrodinger non linéaire. Ces phénomènes ont été beaucoup étudiés et notamment dans le cas Euclidien. On s'intéresse ici à des cas où l'espace n'est plus l'espace Euclidien. Cela comprend en particulier l'étude des trois prototypes : domaine de l'espace Euclidien, tore (courbure nulle), sphère (courbure positive) et espace hyperbolique (courbure négative). Concernant l'équation de Schrodinger, plusieurs résultats ont montré que la métrique pouvait influencer le comportement qualitatif des solutions, en particulier les propriétés dispersives des solutions et le seuil critique d'existence locale pour le problème de Cauchy. Plusieurs résultats concernant l'explosion sont ensuite venus confirmer ces phénomèmes. Dans cette thèse, on se propose de poursuivre cette étude. / In this thesis, we study blow-up behavior of solutions for dispersive equations, more precisely for the nonlinear Schr"odinger equation. This has been studied essentially in the Euclidean case. In this work, we are interested in the case where the equation is posed on a general manifold; this includes the case of a domain of the Euclidean space, torus (zero curvature); the sphere (non negative curvature) and the hyperbolic space (negative curvature). For the Schr"odinger equation, several results proved that the metric could change the qualitative behavior of the solutions, in particular dispersive properties and the critical threshold of existence for the Cauchy problem. Then, some results showed that blow-up theory is also concerned. In this work, we continue this study.
64

Investigation of the progenitors and outbursts of classical and recurrent novae

Surina, Farung January 2014 (has links)
Classical novae (CNe) are interacting binary systems whose outbursts are powered by a thermonuclear runaway in accreted material on the surface of a white dwarf (WD). The secondary stars in such systems fill their Roche lobe and material is transferred onto the WD primary star via an accretion disk. Recurrent novae (RNe) show many similarities to CNe, but have had more than one recorded outburst. They play an important role as one of the suspected progenitor systems of Type Ia supernovae (SNe) which are used as primary distance indicators in cosmology. Thus, it is important to investigate the nature of their central binary systems to determine the relation between the parameters of the central system and outburst type, and finally ascertain the population of novae that might be available to give rise to the progenitors of Type Ia SNe. The investigation looking for characteristics that may distinguish RNe from CNe systems, the selection of initial targets for detailed study, and results of the investigation are presented in this thesis. The proposal that RNe occupy a region separated from CNe in an outburst amplitude versus speed class diagram was adopted. Since the low amplitude results from the existence of an evolved secondary and/or high mass transfer rate in the quiescent system, RNe candidates should accordingly have low amplitude. The 93 novae with observed V amplitudes given in the literature and 43 novae with photographic amplitudes have been combined and plotted on an outburst amplitude versus rate of decline diagram from which 16 target novae suspected to be RNe candidates were selected for photometric and spectroscopic follow-up. Quiescent photometric magnitudes and spectra were obtained using RATCam on LT, FRODOSpec on LT, and RSS on SALT. Spectral type and luminosity class determined from the near-IR colour-magnitude diagrams were compared to those derived from the spectra. Determination of spectral types was accomplished by identifying specific lines and calculating indices from TiO bands, VO bands, and the Na atomic line for giants (finding 4 stars) and sub-giants/giants (3 stars). A spectral library template was used instead of the indices in cases of main-sequence stars (2 stars).Our investigation also confirmed the positions of AR Cir, V794 Oph and EU Sct where there had been some ambiguity previously. Ultimately, we suggest four prime RNe candidates (2 novae with giant secondaries - V3964 Sgr and EU Sct, and 2 novae with sub-giant secondaries - V794 Oph and V368 Aql) which are currently classified as CNe, to look for more than one outburst in archival plates or large sample sky surveys such as SMEI (see below). By introducing the high cadence full-sky space-based observational archive of the Solar Mass Ejection Imager (SMEI) which operated on the Coriolis satellite from 2003-2011, we derived light curves of one Mira (O Cet) as a general example and two novae with known outbursts during 2003-2011 (V2467 Cyg and V1187 Sco). The SMEI light curves potentially reveal more details than those given by ground-based observations. The pre-maximum halt was found in V2467 Cyg as well as oscillations in light curves found earlier than those found in previous studies. The precise date of maximum of each nova was provided. Four bright novae that are potentially RNe candidates (V4074 Sgr, V3964 Sgr, DK Lac and V368 Aql) were searched for second outbursts in the SMEI data, but none were found. Among the nova outbursts detected by SMEI, we found however unprecedented detail in first class data of the Recurrent Nova T Pyx in its 2011 outburst. We investigated the optical light curve of T Pyx during its 2011 outburst through compiling a database of SMEI and American Association of Variable Star Observers (AAVSO) observations. The SMEI light curve, covering t=1.5-49 days post-discovery, was divided into four phases based on the idealised nova optical light curve; the initial rise (1.5-3.3 days), the pre-maximum halt (3.3-13.3 days), the final rise (14.7-27.9 days), and the early decline (27.9 days, until the end of SMEI observations on day 49). The SMEI light curve contains a strongly detected period of 1.44+-0.05 days during the pre-maximum halt phase. These oscillations resemble those found in recent TNR models arising from instabilities in the expanding envelope. No spectral variations that mirror the light curve periodicity were found however. The marked dip at t~22-24 days just before light curve maximum at t=27.9 days may represent the same (shorter duration) phenomenon seen in other novae observed by SMEI and present in some TNR model light curves. The spectra of T Pyx from the 2m the Liverpool Telescope and the Small and Moderate Aperture Research Telescope System (SMARTS) 1.5m telescope were obtained from t=0.8-80.7 and 155.1-249.9 days, covering the major phases of development. The nova was observed very early in its rise where a distinct high velocity ejection phase was evident with derived Vej~4000 km/s initially. A marked drop at t=5.7 days, and then a gradual increase occurred in derived Vej to stabilise at ~1500 km/s at the pre-maximum halt. Here we propose two different stages of mass loss, a short-lived phase occurring immediately after outburst and lasting ~6 days followed by a more steadily evolving and higher mass loss phase. The overall spectral development follows that typical of a Classical Nova and comparison with the photometric behaviour reveals consistencies with the simple evolving pseudo-photosphere model of the nova outburst. Comparing optical spectra to X-ray and radio light curves, weak [Fe X] 6375A emission was marginally detected before the X-ray rise and was clearly present during the brightest phase of X-ray emission. If the onset of the X-ray phase and the start of the final decline in the optical are related to the cessation of significant mass loss, then this occurred at t~90-110 days.
65

Desenvolvimento de um modelo para a estimativa da máxima sobrepressão gerada em uma explosão de gás / Development of a model to evaluate the maximum overpressure generated in a gas explosion

Matos, Renata Pinto da Silva, 1987- 11 March 2014 (has links)
Orientador: Sávio Souza Venâncio Vianna / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química / Made available in DSpace on 2018-08-26T06:41:15Z (GMT). No. of bitstreams: 1 Matos_RenataPintodaSilva_M.pdf: 3725147 bytes, checksum: 25df8714a04182bf23945239ed396ad9 (MD5) Previous issue date: 2014 / Resumo: A máxima sobrepressão de uma explosão de gás é um dos principais parâmetros estimados em uma Análise de Consequências. Muitas vezes é necessário fazer estimativas iniciais do seu valor, principalmente na fase conceitual de projeto. Portanto um modelo para estimativa da máxima sobrepressão gerada em uma explosão de gás que é de fácil implementação e que possui uma abordagem teórica foi desenvolvido. Ele foi implementado no software de planilhas eletrônicas Microsoft Excel e apresenta tempo de resposta curto. O modelo desenvolvido é baseado no conceito flamelet como apresentado por BML (Bray, Moss e Libby). Ele considera o efeito de obstáculos na aceleração da chama em uma explosão dentro de uma câmara em larga escala com vent. A modelagem da energia cinética turbulenta e da sua taxa de dissipação é baseada em fluidodinâmica computacional (CFD). Simulações numéricas foram conduzidas no FLACS (Flame Acceleration Simulator). O desempenho do modelo foi avaliado em três diferentes conjuntos de dados experimentais de explosões de gás em larga escala dentro de câmaras parcialmente confinadas e obstruídas similares a um módulo offshore: os experimentos da British Gas, Shell e DNV. O modelo foi capaz de representar o aumento da área da chama devido à turbulência causada pela presença de obstáculos para os três experimentos em questão. Espera-se que o modelo seja capaz de representar o mesmo comportamento em geometrias similares à da British Gas sem o ajuste de constantes. Comparações com modelos existentes que não são de CFD mostraram um desempenho muito promissor e uma boa concordância com dados experimentais foi observada / Abstract: The maximum overpressure of gas explosion is one of the main parameters estimated in the Consequence Analysis. Quite often it is necessary to make some initial estimative of its value, particularly in the conceptual design phase. Therefore a model to estimate the maximum overpressure of gas explosion that is easy to implement and have a theoretical approach has been developed. It has been implemented in the Microsoft Excel spreadsheet and it presents a short response time. The developed model is based on the flamelet concept as put forward by BML (Bray, Moss and Libby). It takes into account the effect of obstacles on the flame acceleration in the explosion inside a large scale chamber with vent. The modelling of the turbulent kinetic energy as well as the rate of dissipation of turbulent kinetic energy is based on computational fluid dynamics (CFD). Numerical simulations were conducted in FLACS (Flame Acceleration Simulator). The performance of the model has been verified for three different sets of experimental data from large scale gas explosions inside partially confined and obstructed chambers which are similar to an offshore module: the experiments from British Gas, Shell and DNV. The model was capable of representing the increase of the flame area due to the turbulent field ahead of the flame caused by the presence of obstacles for the three experiments. It is expected that the model is able to represent the same behaviour in geometries similar to the British Gas without the constant adjustment. Comparisons with existing non CFD models have shown a very promising performance and good agreement with experimental data was observed / Mestrado / Sistemas de Processos Quimicos e Informatica / Mestra em Engenharia Química
66

On The Analytic Theory Of Explosions

Yogi, A M Nageswara 07 1900 (has links)
No description available.
67

Characteristics of Reinforced Concrete Bond at High Strain Rates

Jacques, Eric January 2016 (has links)
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.
68

Underwater Pressure Pulses Generated by Mechanically Alloyed Intermolecular Composites

Maines, Geoffrey C. January 2014 (has links)
Recently, the use of thermite-based pressure waves for applications in cellular transfection and drug delivery have shown significant improvements over previous technologies. In the present study, a new technique for producing thermite-generated pressure pulses using fully-dense nano-scale thermite mixtures was evaluated. This was accomplished by evaluation of a stoichiometric mixture of aluminium (Al) and copper(II)-oxide (CuO) prepared by mechanical alloying. Flame propagation speeds, constant-volume pressure characteristics and underwater pressure characteristics of both a micron-scale and mechanically alloyed mixture were measured experimentally and compared with conventional nano-scale thermites. It was determined that mechanically alloyed mixtures are capable of attaining flame propagation speeds on the same order as nano-scale mixtures, with flame speeds reaching as high as approximately 100 m/s. Constant-volume pressure experiments indicated that mechanically alloyed mixtures result in lower pressurization rates compared with conventional nano-scale mixtures, however, an improvement by as much as an order of magnitude was achieved compared with micron-scale mixtures. Thermochemical equilibrium predictions for pressures observed in constant-volume reactions were found to capture relatively well the equilibrium pressure for both low and high values of relative density. Generally, the predictions over-estimated the measured pressures by approximately 60%. Results from underwater experiments indicated that the mechanically alloyed samples produced peak shock pressures and waveforms similar to those for a nano-scale Al-Bi2O3 mixture reported by Apperson et al. (2008). In an effort to model the pressure signal obtained from the underwater reaction, calculations were performed based on the rate of expansion of the high pressure gas sphere. Predicted pressures were found to agree fairly well in terms of both the peak pressure and pressurization rate. The present study has thus identified the ability for mechanically alloyed thermite mixtures to produce underwater pressure profiles that may be conducive for applications in cellular transfection and drug delivery. Récemment, l'utilisation d'ondes de pression produite par des mélanges de thermite pour des applications dans la transfection cellulaire et l'administration de médicaments ont démontré des améliorations importantes par rapport aux technologies précédentes. Dans l'étude ci jointe, une nouvelle technique pour produire des impulsions de pression générée par un mélange thermite, soumit a de l'alliage mécanique, a été évaluée. Ceci a été accompli par l'évaluation d'un mélange stoechiométrique d' aluminium (Al) et de l'oxyde de cuivre(II) (CuO), préparé par mécanosynthèse. Les vitesses de propagation de la flamme, les caractéristiques de pression pour la combustion à volume constant et les caractéristiques de pression pour la combustion sous l'eau ont été mesurées expérimentalement et comparés avec les thermites conventionnel à l'échelle nano. Nous avons déterminé que les mélanges alliés mécaniquement sont capables d'atteindre des vitesses de propagation de flamme du même ordre que les mélanges à l'échelle nanométrique, atteignant jusqu'à environ 100 m/s. Les expériences de combusition à volume constant, indique que les mélanges alliés mécaniquement induit des taux de pressurisation inférieures à celles des mélanges de nano-échelle conventionnel, cependant, une amélioration de près d'un ordre de grandeur a été atteint par rapport aux mélanges d'échelle micronique. Prédictions thermochimiques des pression de compbustion se sont révélés capable de relativement bien saisir les valeurs observées dans les expériences à volume constant. En règle générale, les prévisions sur-estimé les pressions mesurées par environ 60%. Les résultats des expériences sous-marines ont indiqué que les échantillons alliés mécaniquement ont produit des pressions et des profils d'onde similaires à celles produit par un mélange de Al-Bi2O3 de nano-échelle, comme indiqué par Apperson et al. (2008). Pour modéliser les pressions obtenues dans les expériences sous-marines, des calculs basés sur le taux d'expansion de la bulle de gaz à haute pression ont été obtenus. Les pressions prédites ont été trouvés d'être relativement en accord avec la pression maximale et le taux de pressurisation observé. Cette étude a ainsi identifié la possibilité pour l'utilisation des mélanges de thermites alliés mécaniquement pour produire des profils de pression sous l'eau propices pour des applications de transfection cellulaire et l'administration de médicaments.
69

Study of puffing and micro-explosion during the evaporation of Arabian light oil droplets

Restrepo-Cano, Juan 12 1900 (has links)
Although the suspended droplet evaporation and combustion have been studied for decades, fundamental research pertaining to the stochastic phenomena of complex multicomponent mixtures is extremely rare. In this work, an experimental suspended droplet study of Arabian light oil was held to study the frequency of puffing and micro-explosion phenomena during the evaporation/pyrolysis process. The experiments were conducted at three different evaporation temperatures (350 C, 440 C, and 570 C), chosen in accordance with the TGA profle obtained. The suspended droplet experiments were conducted on a furnace with optical access and a gas controlled-preheating system. The droplet size was optically registered at 500 fps by a LaVision Imager Pro HS high-speed camera coupled with a magnification lens Nikon AF-S Micro Nikkor 105 mm. Furthermore, a computer-vision data postprocessing program was developed to identify contours and measure the size of the objects in the frame in order to register the temporal evolution of the droplet size. Additionally, a new approach for characterizing the droplet vaporization of complex multi-component fuels is proposed. This method allowed us to study the continuum (ideal evaporation) and stochastic processes separately, by following the profile of the average normalized square diameter ((D=D0)2) and quantifying the breakup intensity (β) of each stochastic event. Based on the behavior of (D=D0)2, two consecutive stages were identified at every temperature investigated, the swelling and the regression stage. At 350 ◦C and 440 ◦C, the evaporation was finally controlled purely by the diffusion evaporation, whereas at 570 ◦C a pure diffusion stage was not spotted. Instead, a second swelling was registered, where an amorphous carbonaceous structure was formed. Due to the pyrolysis of the heavy hydrocarbons dominated the process. The stochastic events involved during the evaporation were successfully identified and classified in breakup modes depending on their β. Additionally, the effect of the temperature on the breakup events was assessed. Showing that the number of breakup events increased exponentially with temperature.
70

Steam Explosion Pretreatment of Cotton Gin Waste for Fuel Ethanol Production

Jeoh, Tina 15 January 1999 (has links)
The current research investigates the utilization of cotton gin waste as a feedstock to produce a value-added product - fuel ethanol. Cotton gin waste consists of pieces of burs, stems, motes (immature seeds) and cotton fiber, and is considered to be a lignocellulosic material. The three main chemical constituents are cellulose, hemicellulose, and lignin. Cellulose and hemicellulose are polysaccharides of primarily fermentable sugars, glucose and xylose respectively. Hemicellulose also includes small fractions of arabinose, galactose, and mannose, all of which are fermentable as well. The main issue in converting cotton gin waste to fuel ethanol is the accessibility of the polysaccharides for enzymatic breakdown into monosaccharides. This study focused on the use of steam explosion as the pretreatment method. Steam explosion treatment of biomass has been previously described to increase cellulose accessibility. The governing factors for the effectiveness of steam explosion are steam temperature and retention times. The two factors are combined into a single severity term, log(Ro). Following steam explosion pretreatment, cotton gin waste was subjected to enzyme hydrolysis using Primalco basic cellulase. The sugars released by enzyme hydrolysis were fermented by a genetically engineered Escherichia coli (Escherichia coli KO11). The effect of steam explosion pretreatment on ethanol production from cotton gin waste was studied using a statistically based experimental design. The results obtained from this study showed that steam exploded cotton gin waste is a heterogeneous material. Drying and milling of steam exploded cotton gin waste was necessary to reduce variability in compositional analysis. Raw cotton gin waste was found to have 52.3% fermentable sugars. The fiber loss during the steam explosion treatment was high, up to 24.1%. Xylan and glucan loss from the pretreatment was linear with respect to steam explosion severity. Steam explosion treatment on cotton gin waste increased the hydrolysis of cellulose by enzyme hydrolysis. Following 24 hours of enzyme hydrolysis, a maximum cellulose conversion of 66.9% was obtained at a severity of 4.68. Similarly, sugar to ethanol conversions were improved by steam explosion. Maximum sugar to ethanol conversion of 83.1% was observed at a severity of 3.56. The conclusions drawn from this study are the following: steam explosion was able to improve both glucose yields from enzyme hydrolysis and ethanol yields from fermentation. However, when analyzed on whole biomass, or starting material basis, it was found that the fiber loss incurred during steam explosion treatment negated the gain in ethanol yield. / Master of Science

Page generated in 0.0698 seconds