Basic research in wake vortex alleviation using a variable twist wing

The variable twist wing concept was used to investigate the relative effects of lift and turbulence distribution on the rolled up vortex wake. Several methods of reducing the vortex strength behind an aircraft were identified. These involve the redistribution of lift spanwise on the wing and drag distribution along the wing. Initial attempts to use the variable twist wing velocity data to validate the WAKE computer code have shown a strong correlation, although the vorticity levels were not exactly matched

Low-speed wind-tunnel investigation of wing fins as trailing-vortex-alleviation devices on a transport airplane model

The trailing-vortex-alleviation effectiveness of both a one- and a two-fin configuration (semicircular with a radius of 0.043 semispan) on a jumbo-jet transport airplane model in its landing configuration was investigated in the Langley V/STOL tunnel, by the trailing-wing sensor technique. The fins were located on the upper surface of the transport model wing along the 30-percent-chord line. The fin configurations were effective in reducing the vortex-induced rolling moment, by amounts varying from 28 to 60 percent, on the trailing wing model located at a distance of 7.8 transport model wing spans downstream of the transport model. The flow over the fins and over the transport airplane model wing downstream of the fins was observed to be separated and turbulent. All fin configurations caused a reduction in maximum lift coefficient, a positive increment in drag coefficient, and an increment in nose-up pitching-moment coefficient on the transport airplane model

Detailed pressure distribution measurements obtained on several configurations of an aspect-ratio-7 variable twist wing

Detailed pressure distribution measurements were made for 11 twist configurations of a unique, multisegmented wing model having an aspect ratio of 7 and a taper ratio of 1. These configurations encompassed span loads ranging from that of an untwisted wing to simple flapped wings both with and without upper-surface spoilers attached. For each of the wing twist configurations, electronic scanning pressure transducers were used to obtain 580 surface pressure measurements over the wing in about 0.1 sec. Integrated pressure distribution measurements compared favorably with force-balance measurements of lift on the model when the model centerbody lift was included. Complete plots and tabulations of the pressure distribution data for each wing twist configuration are provided

Living in a Battleground: Presidential Campaigns and Fundamental Predictors of Vote Choice

Little evidence links the strategic decisions of campaigns to individual-level voting behavior. Yet for campaigns to matter in the way that experts argue, exposure to campaigns must also matter so there should be observable differences in the structure of vote choice between battleground and non-battleground states. Combining presidential campaign data with the Senate Election Study, we show that intense campaigning can activate factors like race, ideology, partisanship, and presidential approval. We find that the campaigns affected different variables in 1988 than in 1992, which we hypothesize is the consequence of campaign messages

The Major Veins of Mesomorphic Leaves Revisited: Tests for Conductive Overload in Acer saccharum (Aceraceae) and Quercus rubra (Fagaceae)

Many leaves survive the severing of their major veins in apparently excellent health. According to the classical explanation, the leaf minor veins provide "conductive overload," an excess of parallel conductive paths, rendering the major veins hydraulically dispensable. Whether such an excess of conductive paths exists has important implications for vascular design and for leaf response to vascular damage. We subjected leaves of Acer saccharum and Quercus rubra to cutting treatments that disrupted the major vein system and determined leaf survival, stomatal conductance (g), quantum yield of photosystem II (Phi(PSII)), and leaf hydraulic conductance (K-leaf). For A. saccharum, the cuts led to the death of distal lamina. For Q. rubra, however, the treated leaves typically remained apparently healthy. Despite their appearance, the treated Q. rubra leaves had a strongly reduced K-leaf,K- relative to control leaves, and g and Phi(PSII) were reduced distal to the cuts, respectively, by 75-97% and 48-76%. Gas exchange proximal to the cuts was unaffected, indicating the independence of lamina regions and their local stomata. Analogous results were obtained with excised Q. rubra leaves. These studies demonstrate an indispensable, vital role of the major veins in conducting water throughout the lamina.Organismic and Evolutionary Biolog

The structure of preserved information in quantum processes

We introduce a general operational characterization of information-preserving structures (IPS) -- encompassing noiseless subsystems, decoherence-free subspaces, pointer bases, and error-correcting codes -- by demonstrating that they are isometric to fixed points of unital quantum processes. Using this, we show that every IPS is a matrix algebra. We further establish a structure theorem for the fixed states and observables of an arbitrary process, which unifies the Schrodinger and Heisenberg pictures, places restrictions on physically allowed kinds of information, and provides an efficient algorithm for finding all noiseless and unitarily noiseless subsystems of the process

IMPACT: The Journal of the Center for Interdisciplinary Teaching and Learning. Volume 8, Issue 2, Summer 2019

Many of us look for ways to help students forge concrete connections between their academic studies and the real world. Universities encourage professors to develop community-based learning, allowing students to contribute to the community beyond their campus in a way that enhances their academic studies and enables them to create these connections. Scholars have theorized the many benefits of community-based learning, but professors have many questions about how to implement community-based learning in practice. What does a successful community-based learning assignment look like? What are the different ways to assess students’ learning experiences in community-based learning assignments? How can one build effective partnerships with community organizations? In these pages, you will find practical advice, theoretical framework, and firsthand accounts of community-engaged teaching across disciplines. Learn from professors who have designed assignments allowing students to complete community projects with refugees, prisoners, veterans, elementary school children, science museums, nursing homes, public libraries, and ESL populations. Students in an Anthropology course, for instance, conduct oral history interviews with refugees, and provide written transcriptions of the interviews that the refugees can then use as a learning tool in ESL classes. In a Science Methods class, students collaborate with an aquarium to produce meaningful exhibits that educate the public. First-year writing students work with veterans to create autobiographical films and write papers related to the project