Mixed convection in a downward flow in a vertical duct with strong transverse magnetic field

The downward flow in a vertical duct with one heated and three thermally insulated walls is analyzed numerically using the two-dimensional approximation valid in the asymptotic limit of an imposed strong transverse magnetic field. The work is motivated by the design of liquid metal blankets with poloidal ducts for future nuclear fusion reactors, in which the main component of the magnetic field is perpendicular to the flow direction and very strong heating is applied at the wall facing the reaction chamber. The flow is found to be steady-state or oscillating depending on the strengths of the heating and magnetic field. A parametric study of the instability leading to the oscillations is performed. It is found among other results that the flow is unstable and develops high-amplitude temperature oscillations at the conditions typical for a fusion reactor blanket

On the law of the iterated logarithm for continued fractions with sequentially restricted partial quotients

We establish a law of the iterated logarithm (LIL) for the set of real numbers whose $n$-th partial quotient is bigger than $\alpha_n$, where $(\alpha_n)$ is a sequence such that $\sum 1/\alpha_n$ is finite. This set is shown to have Hausdorff dimension $1/2$ in many cases and the measure in LIL is absolutely continuous to the Hausdorff measure. The result is obtained as an application of a strong invariance principle for unbounded observables on the limit set of a sequential iterated function system.Comment: Improved bounds for $(\alpha_n)

Akchessima: Latin Type Design for Digital Chinese (Seal Script) Typefaces

As multi-language text layout and Chinese/Japanese/Korean typefaces has become an important topic in modern day typography, the visual match-making between Latin and Chinese writing is a very important issue in type design. For this thesis project, Latin letters are designed based on a Chinese seal script style typeface, in seek of a design principle of matching Latin letter forms for Chinese calligraphic styles, originating from different writing tools and traditions. There is not one universal principle that would apply on all different Chinese typeface styles. However, based on research of writing habits and technology, multiple methods have been developed in this thesis, which could be used while processing any type design projects

Computations of Flow Fields of an Airfoil and a Wing with Gurney Flap in Ground Effect

High lift devices used in transport aircraft are complex multi-element wings with slats and flaps which are difficult to design and they incur high manufacturing and maintenance costs. Taking all requirements into consideration, for light aircrafts using Gurney Flap may offer a low cost, low maintenance solution for improving the aerodynamic performance of aircraft during take-off and landing. Gurney Flap, first invented by Dan Gurney, is a small tab projecting from the trailing edge of airfoil. Gurney Flap can increase the lift coefficient and decrease the angle of attack for zero lift. However, at low angle of attack, Gurney flap also increases the drag coefficient. Overall, a net benefit in the lift-to-drag ratio can be provided by Gurney Flap since it increases the pressure on the lower surface of the airfoil upstream of the Gurney Flap. For generating the same lift force, less suction on the upper surface is needed with Gurney Flap. The effect of ground on a clean airfoil at moderate angles of attack is to increase the lift force and decrease the aerodynamic drag. The obstruction due to the ground increases the pressure on the lower surface of the wing and weakens the trailing vortices form the wing. This effect of ground on the airfoil aerodynamics has been demonstrated experimentally and computationally by many investigators. While the ground effect of a single airfoil and a multi-element airfoil has been studied for decades, few studies have been conducted on the ground effect due to a Gurney Flap. The goal of this thesis is to perform numerical simulations of flow over an airfoil/wing with a Gurney flap in ground effect and analyze its aerodynamic performance and flow physics

Structure of turbulence in combined wave-current boundary layers

This thesis is based on an experimental programme conducted in two laboratory flumes with different scales, to examine the near bed boundary layer under combined surface waves and a turbulent current. Flow conditions have covered a range of wave frequencies and amplitudes, and current conditions. The results give an enhanced understanding of turbulence structures close to the bed in a combined wave-current flow, in terms of coherent vortices and eddy viscosities. A two-dimensional Particle Image Velocimetry system was used to measure the velocity field. Average properties of turbulence characteristics were determined. Hydrogen bubble techniques were employed to provide flow visualisation of the near-wall flow patterns. Results for the unidirectional current are consistent with many previous studies on the existence of coherent vortices. In particular, the measured flow velocity vectors and contours of magnitude demonstrate the presence of low-speed and high-speed streaks in the wall region and bursts in the outer flow. Further quantitative analysis also shows that the characteristic length scales agree well with previous research. For tests with combined wave-current flow, results demonstrate that streamwise vortices are also present. However, the spacing between adjacent low-speed streaks changes periodically within one wave cycle. In addition, measurements also reveal that the maximum Reynolds shear stress induced by ejections is increased when waves are superimposed on the turbulent current. The increase is observed to be more significant for waves with higher frequencies and amplitudes. In order to relate turbulent behaviour with time-averaged velocities in a combined wave-current boundary layer, an eddy viscosity distribution was computed based on experimental results from the flumes and a large oscillating water tunnel from previous tests. These results show a different distribution from those in existing models of wave-current interaction. These results are expected to improve the accuracy on prediction of the hydrodynamics and sediment transport in combined wave-current flows

Portrayals of gay characters in Chinese movies: A longitudinal look

ABSTRACT Homosexuals were considered criminals and abnormal in China, and the majority of Chinese homosexuals still hide in the shadows, especially in the mainland. However, demands of cultural pluralism and human rights are beginning to show a sign of tolerance to the minority group, especially among the younger generation. As a powerful form of mass media, motion pictures can create images of certain people, affecting the audience\u27s evaluation of a specific group or situation. This study examines the portrayals of gay characters in Chinese films over a sixteen-year period, focusing on the characters\u27 visibility (explicit or implicit), representation (positive or negative), and characterizations. A qualitative content analysis of ten Chinese movies with homosexual themes or having a sufficient role for a homosexual character was conducted. The sample covered movies released from 1993 to 2009. To be included in the study, the films must have been directed by a Chinese director and performed by Chinese actors, and set in Mainland China or a Chinese community. The result shows filmmakers of the analyzed movies tried to humanize them in an apparent effort to evoke sympathy toward and understanding of their plight. And most gay characters in the films suffered oppression from the society and their family. However, the government censorship severely limited the number and funding opportunities of homosexual-themed movies, making it difficult for such films to earn a profit. Even though some filmmakers and younger filmgoers are willing to bring the gay lifestyle into the light, government restrictions on content and distribution of the pictures has limited their exposure. And so the portrayal of gays in films has remained essentially the same during the years covered in the study. But a slight thaw in government regulation has allowed some gay characters to appear in mainstream movies, providing some indication that times are changing

Targeting Oncogenic Protein Sythesis in MYC-driven B Cell Lymphoma

Burkitt lymphoma (BL) and diffuse large B-cell lymphoma (DLBCL) are aggressive tumors of mature B cells that can be distinguished based on histomorphological, phenotypic, and genetic features. B-cell lymphoma unclassifiable, with features intermediate between BL and DLBCL (BCL-U) is a subset of mature B cell lymphoma contains one or more features that overlap BL and DLBCL. Previous molecular analyses prove there is a biological continuum between BL and DLBCL based on the activity of MYC. Herein, in order to resolve the molecular heterogeneity of BCL-U, we tested whether a targeted expression profiling panel could categorize tumors as BL and DLBCL. Among these MYC driven lymphomas, those with concurrent MYC and BCL2 dysregulation are especially a challenge in clinical practice due to rapid disease progression, resistance to standard chemotherapy and high risk of refractory. MYC plays a central role by coordinating hyperactive protein synthesis with upregulated transcription in order to support the rapid proliferation. Translation initiation inhibitor rocaglates were identified as the most potent drug across all MYC driven lymphomas as they efficiently inhibit MYC expression and tumor cell viability. Surprisingly, we found this class of compounds does not inhibit translation by depleting the abundance of eIF4A in eIF4F, but more likely acts as a selective roadblock to prevent ribosome scanning. Furthermore, proteome wide quantification demonstrated rocaglate induced selective repression of multiple critical oncoproteins beside MYC in B cell lymphoma including NEK2, MCL1, AURKA, PLK1 and several transcription factors that generally considered undruggable. Finally, (-)-SDS-1-021, the most promising rocaglate, was confirmed highly potent as single agent, and displayed significant synergy with BCL2 inhibitor ABT199 in inhibiting tumor growth and survival in patient derived xenograft mouse models. Overall, our findings support the strategy of using rocaglates to target oncoprotein synthesis in MYC-driven lymphomas

Dithienopyrrole-based conjugated materials for organic electronics

Dithienopyrrole-based conjugated materials, including oligomers and polymers, for potential organic electronic applications, were designed, synthesized and characterized. The optical and electrochemical properties of these materials were investigated, and their structure-property relationships were studied. Some of the materials can be oxidized (or reduced) chemically or electrochemically. Furthermore, the utility of these materials in organic electronic devices, such as OFETs and OPVs, were assessed. In OFETs, they can function as hole-transport materials with mobilities up to 4.8 × 10-2 cm2/(Vs), and one example serves as an ambipolar material with comparable hole and electron mobilities of 1.2 × 10-3 and 5.8 ×10-4 cm2/(Vs), respectively. Some of the materials can also be used as electron donors in OPVs in conjunction with PCBM, and exhibited power conversion efficiencies up to 1.4% after optimizations. They may also be used in other applications such as electrochromic devices, photodetectors, and optical limiting.Ph.D.Committee Chair: Marder, Seth; Committee Member: Bredas, Jean-Luc; Committee Member: Kippelen, Bernard; Committee Member: Perry, Joseph; Committee Member: Tolbert, Lare