An Intuitive Approach to Geometric Continuity for Parametric Curves and Surfaces (Extended Abstract)

The notion of geometric continuity is extended to an arbitrary order for curves and surfaces, and an intuitive development of constraints equations is presented that are necessary for it. The constraints result from a direct application of the univariate chain rule for curves, and the bivariate chain rule for surfaces. The constraints provide for the introduction of quantities known as shape parameters. The approach taken is important for several reasons: First, it generalizes geometric continuity to arbitrary order for both curves and surfaces. Second, it shows the fundamental connection between geometric continuity of curves and geometric continuity of surfaces. Third, due to the chain rule derivation, constraints of any order can be determined more easily than derivations based exclusively on geometric measures

Shape change of Galileo probe models in free-flight tests

Scale models of the Galileo Probe made of polycarbonate, AXF5Q graphite, carbon-carbon composite, and carbon-phenolic were flown in a free flight range in an ambient gas of air, krypton, or xenon. Mach numbers varied between 14 and 24, Reynolds numbers between 300,000 and 1,000,000, stagnation pressures between 31 and 200 atm, and stagnation point heat transfer rates between 10 and 1,000 kW/sq cm. Shadowgraphs indicate gouging ablation of the aft portion of the frustum; the gouging was moderate in air and severe in the noble gases. The graphite models break in the same region. An explanation of the phenomena is offered in terms of the strong compression and shear caused by the reattachment of a turbulent separated flow. Conditions are calculated for similar tests appropriate for Von Karman Facility of the Arnold Engineering Development Center in which a larger model can be flown in argon

-1 V bias 56 Gbps germanium waveguide p-i-n photodetector with silicon contacts

We demonstrate a silicon-contact-only 56 Gbps germanium waveguide photodetector operating at -1 V. The dark current is below 4 nA and the responsivity is 0.74 A/W at 1550 nm and 0.93 A/W at 1310 nm

Electrically pumped edge-emitting photonic crystal lasers with angled facets

We demonstrate electrically pumped large-area edge-emitting InGaAsP/InP two-dimensional photonic crystal lasers with angled facets at room temperature. The laser uses a weak index perturbation surface photonic crystal structure to control optical modes in the wafer plane. Measurements of the laser spectra show that the modal selection is due to satisfying the Bragg resonance conditions in both the longitudinal and the transverse directions. The lasing wavelength is tuned lithographically by changing photonic crystal lattice constants. We demonstrate a fine lasing wavelength tuning sensitivity (change of lasing wavelength over change of lattice constant) of 0.08 through the transverse lattice constant tuning

Seize the Revision: A Critical Introduction to a Collection of Poetry Titled “Fill in the Blank”

Poetry is all about having a passion for language and its fluidity. It is also about constantly reworking language until it flows just as it needs to flow. The process of revision is not about making something better or even about making something complete. It is about playing around with words and erasing and discovering and crossing out and replacing. This introduction to my collection of poems is going to be talking about the process of revision. First, I will talk about other poets that I have read and their different revising processes in the section titled “Revising Poems.” Then, I will reflect on poets that have been an inspiration to me and directly influenced my writing or revision process in the section titled “Inspirations.” Last, I will point out specific examples in my collection of poems, Fill in the Blank, and in the subsequent drafts of my revisions. I will explore which techniques I personally found worked best for my writing process. It is in this last section, titled “Personal Techniques,” where I will incorporate my own poems and compare their numerous included drafts side-by-side

Size Structure, Age, Growth and Spawning Periodicity of Silver Carp Hypophthalmichthys molitrix in Kentucky Lake, Kentucky

Invasive species are a growing threat to aquatic ecosystems in the United States. Invasive species can compete with native species, alter habitats and reduce ecosystem function. A recent invader, Silver Carp Hypophthalmichthys molitrix, has successfully infiltrated much of the Mississippi River Basin and has established reproducing populations within the Illinois, Mississippi, Missouri and Tennessee Rivers. In 2004 Silver Carp were reported within Kentucky Lake, a large reservoir located on the Tennessee River in Western Kentucky. Although Silver Carp have been present in Kentucky Lake for over a decade, very little is known about the population, which makes it difficult to predict the potential impact of Silver Carp on native species as well as the future trajectory of the population. Information regarding population dynamics (i.e., recruitment, growth and mortality) is important for managers as well as commercial and recreational fishermen. Our first objective was to describe population dynamics of the Silver Carp population within Kentucky Lake, focusing on size structure, age structure and growth rates. Our second objective was to determine when Silver Carp spawn within Kentucky Lake by analyzing mean monthly gonadosomatic index (GSI). Silver Carp were collected from Kentucky Lake using a variety of sampling methods including gill nets, boat electrofishing, cast nets and commercial fishing. Preliminary data suggest that the Silver Carp population within Kentucky Lake is composed of one or two significant year-classes. These data are critical for modeling the future trajectory of the Silver Carp population within Kentucky Lake

Vertically emitting annular Bragg lasers using polymer epitaxial transfer

Fabrication of a planar semiconductor microcavity, composed of cylindrical Bragg reflectors surrounding a radial defect, is demonstrated. A versatile polymer bonding process is used to transfer active InGaAsP resonators to a low-index transfer substrate. Vertical emission of in-plane modes lasing at telecom wavelengths is observed under pulsed optical excitation with a submilliwatt threshold

Informal Discussion

What types of problems--whether methodological, pedagogical, or philosophical--are unique to Berkeley scholarship