Flameless combustion in a 48 kW pilot scale furnace fired with natural gas is studied experimentally and computationally. The burner geometry involved a tunnel furnace with two separate feed streams --- one for a high momentum air jet and the other for a low momentum fuel jet. This burner configuration, called a Strong-Jet/Weak-Jet (SJWJ) burner, together with the jetto- jet interactions generate the flameless combustion mode with relatively uniform furnace gas temperature distributions and low NOX emissions. Experiments were carried out under laboratory conditions for turbulent reactive mixing in order to obtain local temperature and gas concentrations. The experimental findings were used to test the performance of CFD numerical models for turbulence, mixing and chemical reactions. For the SJWJ furnace operated in flameless combustion mode, 32 different flow cases were examined to assess the effects of the three main parameters (fuel/air momentum flux ratio, fuel/air nozzle separation distance and fuel injection angle) on the furnace wall temperature profile. Three specific flow configurations were selected for detailed near-field temperature measurements. The gas temperature distribution inside the combustion chamber was found to be relatively uniform, a characteristic of flameless combustion. Four flow configurations were studied to examine the effect of the fuel jet injection angle (0 degrees or 10 degrees) and fuel/air momentum flux ratio (0.0300 and 0.0426) on the mixing, combustion performance and NOX emissions. Gas compositions were measured in the flue gas and within the furnace at selected locations to estimate the concentrations of CO2 CO, CH4, O2, NO and NOX. The NOX concentrations in the flue gas were quite low, ranging from 7 - 13 ppm, another characteristic of flameless combustion. The combusting flow CFD calculations were carried out using the k-ε turbulence model and the eddy-dissipation model for methane-air-2-step reactions to predict the temperature and concentration field. The numerical results for gas temperature and compositions of CH4, O2 and CO2 generally showed good agreement with the experimental data. The predicted CO concentration profiles followed expected trends but the experimental data were generally underpredicted. The NOX concentrations were estimated through post-processing and these results were significantly underpredicted. / Thesis (Ph.D, Mechanical and Materials Engineering) -- Queen's University, 2008-04-04 11:25:25.455

No description available.

The MuSun experiment will determine the μd capture rate (μ−+d ->n+n+νe) from the doublet hyperfine state Λd, of the muonic deuterium atom in the 1S ground state to a precision of 1.5%. Modern effective field theories (EFT) predict that an accurate measurement of Λd would determine the two-nucleon weak axial current. This will help in understanding all weak nuclear interactions such as the stellar thermonuclear proton-proton fusion reactions, the neutrino reaction ν+d (which explores the solar neutrino oscillation problem). It will also help us understand weak nuclear interactions involving more than two nucleons — double β decay — as they do involve a two-nucleon weak axial current term. The experiment took place in the πE3 beam-line of Paul Scherrer Institute (PSI) using a muon beam generated from 2.2 mA proton beam — which is the highest intensity beam in the world. The muons first passed through entrance scintillator and multiwire proportional chamber for determining thier entrance timing and position respectively. Then they were stopped in a cryogenic time projection chamber (cryo- TPC) filled with D2 gas. This was surrounded by plastic scintillators and multiwire proportional chambers for detecting the decay electrons and an array of eight liquid scintillators for detecting neutrons. Muons in deuterium get captured to form μd atoms in the quartet and doublet spin states. These atoms undergo nuclear capture from these hyperfine states respectively. There is a hyperfine transition rate from quartet-to-doublet state — λqd along with dμd molecular formation which further undergoes a fusion reaction with the muon acting as a catalyst (MCF). The goal of this dissertation is to measure the dμd quartet-to-doublet rate ratio (λq : λd) and μd hyperfine rate (λqd) using the fusion neutrons from μ− stops in D2 gas. The dμd molecules undergo MCF reactions from the doublet and the quartet state with rates λq and λd and yield 2.45 MeV monoenergetic fusion neutrons. Encoded in the time dependence of the fusion neutrons are the dμd formation rates λq, λd and hyperfine rate λqd . Consequently, the investigation of the fusion neutron time spectrum enables the determination of these kinetics parameters that are important in the extraction of Λd from the decay electron time spectrum. The final results of this work yield λq : λd = 85.51 ± 3.25 and λqd = 38.49 ± 0.21 μs−1.

In this thesis, investigations into the suitability of three 'weak-link' models, designed for the simulation of superconducting cluster systems, are reported. The focus of the investigation is on both the accuracy of the transport properties produced by these models, and the time taken to produce their results. The thesis develops the theory behind a previous approach which was exclusively used to model percolation systems for coverages below the critical coverage. The modifications made allow the simulations to extend to system coverages above the critical coverage. An additional 'current-ramping' algorithm, to simulate the systematic increase or decrease of current forced through the system, is described and explored. The results for the three models are compared, and their suitability for future investigations is discussed.

We consider weak convergence of a sequence of asset price models (Sn) to a limiting asset price model S. A typical case for this situation is the convergence of a sequence of binomial models to the Black-Scholes model, as studied by Cox, Ross, and Rubinstein. We put emphasis on two different aspects of this convergence: firstly we consider convergence with respect to the given "physical" probability measures (Pn) and secondly with respect to the "risk-neutral" measures (Qn) for the asset price processes (Sn). (In the case of non-uniqueness of the risk-neutral measures also the question of the "good choice" of (Qn) arises.) In particular we investigate under which conditions the weak convergence of (Pn) to P implies the weak convergence of (Qn) to Q and thus the convergence of prices of derivative securities. The main theorem of the present paper exhibits an intimate relation of this question with contiguity properties of the sequences of measures (Pn) with respect to (Qn) which in turn is closely connected to asymptotic arbitrage properties of the sequence (Sn) of security price processes. We illustrate these results with general homogeneous binomial and some special trinomial models. (author's abstract) / Series: Report Series SFB "Adaptive Information Systems and Modelling in Economics and Management Science"

This thesis investigates strengthening slender steel columns with carbon fibre reinforced polymer (CFRP) plates of various moduli. Three different types of CFRP were used in the study: Ultra-high modulus (430GPa), High modulus (212GPa) and Normal modulus (168GPa). In this study, specimens were grouped according to measured initial out-of-straightness values. The first section examines the effect of adding CFRP plates to the column flanges when buckling about the weak axis. Twelve columns, with a slenderness ratio of 197, were tested, of which nine were strengthened with CFRP. The main parameters tested were the level of initial out-of-straightness (length (L)/8387 to L/1020), CFRP modulus (168 to 430 GPa), CFRP reinforcement ratio (13% to 34%) and the length of CFRP plate (33% to 95% of L). The gain in axial strength due to CFRP retrofitting ranged from 11% to 29%, depending on the various parameters. The gain generally increased as CFRP modulus, initial out-of-straightness, or CFRP reinforcement ratio increased. Global buckling consistently governed the maximum load. In the case of the 430 GPa CFRP, buckling was followed by CFRP crushing in compression, then rupture in tension. The second section of the thesis examines the effect of CFRP plates added to the flanges and tested for buckling in the strong axis. Eight columns, with a slenderness ratio of 83, were tested of which five were strengthened with CFRP. The main parameters examined were the level of initial out-of-straightness (L/28889 to L/1635), CFRP modulus (168 to 430 GPa), CFRP reinforcement ratio (13% to 34%) and the axis of bending. The gain in axial strength due to CFRP retrofitting ranged from 0% to 25%, depending on the various parameters. The gain generally increased as initial out-of-straightness, or CFRP reinforcement ratio increased. The higher modulus did not perform as expected, showing no gain in strength, because the compressive strains were too large and the CFRP crushed before the specimen experienced any gain. Specimens compared with the weak axis, strengthened with normal modulus CFRP, had similar percentage gains in strength. / Thesis (Master, Civil Engineering) -- Queen's University, 2014-06-27 15:19:03.397

This paper starts where previous research in this scientific field, research about individuals who managed to end their criminal lifestyle, ends – by talking in terms of Pierre Bourdieu’s forms of capital. In former studies the researchers pointed out access to a job and parenting as helpful factors to end a criminal lifestyle. Our purpose with this paper, however, was to find out if it is possible to understand criminals successfully ending their criminal lifestyle from Bourdieu’s capital metaphors and Mark Granovetter’s concept of strong and weak ties. The empirical data consists of interviews with a life story perspective by eight members of an organization called KRIS (Criminals Return Into Society). All the interviewees included in this study have managed to end their respective criminal lifestyle. The results indicate that our interviewees had help in their ending of the criminal lifestyle by access to or by establishing social capital. The social capital in the interviewees’ cases were constituted by on one hand strong ties, on the other hand weak ties. In a couple of cases both types of ties were involved. Nevertheless, the results indicate that the social capital itself cannot make an ending of the criminal lifestyle possible. The following factors in the individual’s life has to be fulfilled in order to end his or hers criminal lifestyle: (1) exhort a strong motive inside him-/herself, (2) accept no drug use of any kind and (3) carry through a switch of field from the criminal society to the conventional.

Several techniques exist for retrieving and studying information about the properties of the Solar atmosphere from the polarization state of spectral lines. These are commonly called spectral diagnostics. Among the current problems to which these are applied, one is to understand the interconnection between the solar magnetic field and chromospheric heating. Non-LTE inversion has so far been the most reliable method for inferring chromospheric magnetic fields from high-resolution spectropolarimetric observations. However, if the magnetic field is sufficiently low that the line is in the weak field regime, the weak field approximation is often used as a complement. The latter allows for rapid analysis of large datasets and can be used to infer the vector components of the magnetic field. The reliability of the approximation in highly dynamic and stratified atmospheres has however not been well studied. The purpose of this project is to study and assess the reliability, the validity conditions, and the origin of possible breakdowns of the weak field approximation. This is done by computing the magnetic field of a model chromosphere, performed with realistic three-dimensional magnetohydrodynamics, from synthetic Ca II 8542 polarization profiles. Real magnetic fields are further on inferred from sunspot and plage observations of the same line with the intention to test the method under observational constraints. Stokes I profiles with peculiar shapes are seen in both sunspots and plage, apart from the common quiet profiles. The effect of two such types on the inferred field is studied more closely in this project; raised core profiles, which exhibit a flat core and are common in plage and in the vicinity of bright points, and umbral flashes, which exhibit core emission and are seen in sunspots. The shape of the former is directly connected to presence of steep vertical temperature gradients arising from chromospheric heating, while that of the latter is due to oscillatory motions of the plasma. The weak field approximation works well for observations with high S/N ratio and where quiet profiles are abundant, such as in sunspots. It is vulnerable in plage regions where there is an abundance of raised core (RC) or umbral flash (UF) profiles which lead to failed estimations. Profiles with low S/N tend to yield failed estimations as well. This is common where there is plage, whereby clusters of failed inversions tend to arise in such regions. The vertical component and inclination are well determined, while the horizontal component and azimuth are less well determined. The approximation works well in general, and allows for a rapid and efficient inference of the magnetic field vector as long as the wavelength range is chosen wisely.

Firms in highly dynamic environments focusing on innovation in their products and services, often encounter elevated amounts of uncertainty regarding the future direction of technological change. Finding reliable and imbedded information enhances a firm’s ability to tackle new markets and take advantage of possible hidden opportunities. To reduce uncertainty, obtain hidden knowledge, and gain competitive advantage, environmental scanning, which is one of the main components of foresight, is recommended by scholars of strategic management. The process of detecting weak signals for shedding light what one authority calls “blurry future zones” (Day & Schoemaker, 2005, p.1) has currently been receiving attention in environmental scanning studies. Some studies emphasize the importance of the subject; yet they offer few practical methodologies for actual cases. To help address this gap, this research introduces a new approach for detecting weak signals during Internet-based environmental scanning by applying the Cluto toolkit (see Section 4.7) plus using human judgment. This novel methodology is applied to the application of Micro Tiles, a recent innovative product of a digital display company located in Ontario, Canada, Christie Digital Company. In the conduct of this exploratory research, about 40,000 HTML pages were retrieved from the Internet in a search during 2009. To extract weak signals information from the retrieved unstructured texts, documents were grouped into a number of clusters by the CLUTO software. Two subject matter experts compared and evaluated the cluster results for the purpose of finding potentially relevant information in regard to the company’s strategic intent. Analyzing the clusters, the experts reduced the number of clustered documents from the original corpus into smaller sets with the goal of finding more relevant and unexpected documents (weak signals). The relevancy and expectedness of information in documents were two measurements as related to weak signals. The trends of the study indicate that as anticipated both experts found more unexpected documents in the smaller sets rather than the larger ones. Moreover, regarding one expert’s analysis, the smaller sets contain documents that are more relevant to the domain of interest. Overall, according to one expert, documents existing in the smaller sets display more weak signals. This emerging methodology offers a practical procedure to apply web-based information in the development of a company’s environmental scanning procedures. Using this methodology, managers can employ both computer tools and human sense-making methods to detect potential weak signals and reduce certain biases in the detection process.

The aim of this project was to explore the shapes of dark matter halos using high resolution N-body simulations. One of the main aspects explored was how well the shape can be measured through weak lensing. To explore this, simulations were run using the GADGET-2 code \cite{SPRING05} and a method used to measure ellipticities was tested \cite{oguri1}. It was found that Large Scale Structure along the line of sight diluted the measurements and made halos appear more spherical. On the other hand, substructure close to the halo introduced a bias where intrinsically elliptical halos appeared to be slightly more spherical and intrinsically spherical halos appeared to be slightly more elliptical. The effects of projection on concentration were also explored, it was concluded that halos which are most elliptical in 3D tend to appear the most concentrated in projection. Finally, we tested the possibility of using shape or concentration measurements to help break the degeneracy in $\Omega_M$ and $\sigma_8$. We found that this may be possible with $\sim$ 3000-4000 shape measurements or $\sim$ 400-500 concentration measurements.