Status of linear boundary-layer stability and the e to the nth method, with emphasis on swept-wing applications

The-state-of-the-art for the application of linear stability theory and the e to the nth power method for transition prediction and laminar flow control design are summarized, with analyses of previously published low disturbance, swept wing data presented. For any set of transition data with similar stream distrubance levels and spectra, the e to the nth power method for estimating the beginning of transition works reasonably well; however, the value of n can vary significantly, depending upon variations in disturbance field or receptivity. Where disturbance levels are high, the values of n are appreciably below the usual average value of 9 to 10 obtained for relatively low disturbance levels. It is recommended that the design of laminar flow control systems be based on conservative estimates of n and that, in considering the values of n obtained from different analytical approaches or investigations, the designer explore the various assumptions which entered into the analyses

Downstream influence of swept slot injection in hypersonic turbulent flow

Results of an experimental and numerical investigation of tangential swept slot injection into a thick turbulent boundary layer at Mach 6 are presented. Film cooling effectiveness, skin friction, and flow structure downstream of the swept slot injection were investigated. The data were compared with that for unswept slots, and it was found that cooling effectiveness and skin friction reductions are not significantly affected by sweeping the slot

Guidelines for producing rice using furrow irrigation (1991)

New 5/91/5M

Guidelines for producing rice using furrow irrigation (1993)

Traditional rice culture in Missouri uses flood water management. Reasons for flooding include efficient growth, rice's poor water stress tolerance and its ability to flourish in submerged soil where many competitive grasses and broadleaf weeds cannot survive. The purpose of this publication is to introduce producers to the furrow-irrigated rice system and help interested individuals decide whether that system has potential for use on their farms

The POPC Citizen: Political Information in the Fourth Age of Political Communication

A woman checking messages on her phone while standing next to a newspaper rack. A girl waiting in line scrolling down the Facebook timeline, stumbling upon a video clip about the outcome of the recent US presidential elections. A young man playing a game on his tablet, with TV news running in another window. These are just three everyday scenarios that illustrate how today’s “permanently online, permanently connected” (POPC) communication environment has created new conditions for the access to and consumption of political information. A myriad of options to choose from regarding the form and content of communication make it easy to acquire political information continuously, but also to avoid political content given the many other interesting things to do online. At the same time, social networking sites (SNS) have made it more difficult to abstain completely from political information, as they often push news to unsuspecting users. With the permanent potential to activate social ties through SNS and instant messaging services, the political information of citizens has become embedded into their mediated social networks whose members like, share, and comment on it. The implications of widespread digitization and mediatization for the political domain are so profound and far-reaching that they have recently led Jay Blumler (2016) to announce a new “fourth age of political communication.” Political communication in the fourth age is characterized by “yet more communication abundance” (p. 24) compared to the preceding ages, particularly due to new, mobile-access devices that have led to an ever more intense competition for audience attention. The fact that the Internet has gone mobile reinforces developments it initiated much earlier: Mobility increases the frequency of communication and thus the frequency of situations in which more or less conscious choices regarding the modes and content of communication are necessary. Because people often initiate and process digital communication in parallel with an ongoing “offline life,” communication acts may also become more impulsive and automatic (van Koningsbruggen, Hartmann, & Du, this volume), and attention paid to content more superficial than in the past

On the acoustic diffraction by the edges of benthic shells

Author Posting. © Acoustical Society of America, 2004. This article is posted here by permission of Acoustical Society of America for personal use, not for redistribution. The definitive version was published in Journal of the Acoustical Society of America 116 (2004): 239-244, doi:10.1121/1.1675813.Recent laboratory measurements of acoustic backscattering by individual benthic shells have isolated the edge-diffracted echo from echoes due to the surface of the main body of the shell. The data indicate that the echo near broadside incidence is generally the strongest for all orientations and is due principally to the surface of the main body. At angles well away from broadside, the echo levels are lower and are due primarily to the diffraction from the edge of the shell. The decrease in echo levels from broadside incidence to well off broadside is shown to be reasonably consistent with the decrease in acoustic backscattering from normal incidence to well off normal incidence by a shell-covered seafloor. The results suggest the importance of the edge of the shell in off-normal-incidence backscattering by a shell-covered seafloor. Furthermore, when considering bistatic diffraction by edges, there are implications that the edge of the shell (lying on the seafloor) can cause significant scattering in many directions, including at subcritical angles.This research was supported by the U.S. Office of Naval Research (Grant No. N00014-02-1-0095) and the Woods Hole Oceanographic Institution (WHOI), Woods Hole, MA

Computer-controlled characterization of high-voltage, high-frequency SiC devices?

A software-based high-voltage curve tracer application for SiC device characterization is presented. This flexible application interface is developed to define testing parameters needed to control the hardware of a custom-made 25 kV-capable SiC characterization test bed. Data acquisition is controlled for optimum resolution, and I-V characterization is computed by means of a user-defined time interval based on the shape of the applied power pulses. Both voltage and current waveforms are displayed for each data point captured to allow the user to observe transient effects. Additionally, the software allows archiving some or all of these transient waveforms. Acquired results are shown to demonstrate functionality and flexibility of the new system. ©2006 IEEE

Symmetric data-driven fusion of diffusion tensor MRI: Age differences in white matter

In the past 20 years, white matter (WM) microstructure has been studied predominantly using diffusion tensor imaging (DTI). Decreases in fractional anisotropy (FA) and increases in mean (MD) and radial diffusivity (RD) have been consistently reported in healthy aging and neurodegenerative diseases. To date, DTI parameters have been studied individually (e.g., only FA) and separately (i.e., without using the joint information across them). This approach gives limited insights into WM pathology, increases the number of multiple comparisons, and yields inconsistent correlations with cognition. To take full advantage of the information in a DTI dataset, we present the first application of symmetric fusion to study healthy aging WM. This data-driven approach allows simultaneous examination of age differences in all four DTI parameters. We used multiset canonical correlation analysis with joint independent component analysis (mCCA + jICA) in cognitively healthy adults (age 20-33