An investigation of the feasibility of active boundary layer thickening for aircraft drag reduction

The feasibility of using a forward mounted windmilling propeller to extract momentum from the flow around an axisymmetric body to reduce total drag has been studied. Numerical calculations indicate that a net drag reduction is possible when the energy extracted is returned to an aft mounted pusher propeller. However, net drag reduction requires very high device efficiencies. Results of an experimental program to study the coupling between a propeller wake and a turbulent boundary layer are also reported. The experiments showed that a complex coupling exists and simple modes for the flow field are not sufficiently accurate to predict total drag

A general review of concepts for reducing skin friction, including recommendations for future studies

Four main concepts which have significantly reduced skin friction in experimental studies are discussed; suction, gaseous injection, particle additives, and compliant wall. It is considered possible that each of these concepts could be developed and applied in viable skin friction reduction systems for aircraft application. Problem areas with each concept are discussed, and recommendations for future studies are made

In Silico Synchronization of Cellular Populations Through Expression Data Deconvolution

Cellular populations are typically heterogenous collections of cells at different points in their respective cell cycles, each with a cell cycle time that varies from individual to individual. As a result, true single-cell behavior, particularly that which is cell-cycle--dependent, is often obscured in population-level (averaged) measurements. We have developed a simple deconvolution method that can be used to remove the effects of asynchronous variability from population-level time-series data. In this paper, we summarize some recent progress in the development and application of our approach, and provide technical updates that result in increased biological fidelity. We also explore several preliminary validation results and discuss several ongoing applications that highlight the method's usefulness for estimating parameters in differential equation models of single-cell gene regulation.Comment: accepted for the 48th ACM/IEEE Design Automation Conferenc

The Welfare Effects of Pfiesteria-Related Fish Kills: A Contingent Behavior Analysis of Seafood Consumers

We use contingent behavior analysis to study the effects of pfiesteria-related fish kills on the demand for seafood in the Mid-Atlantic region. We estimate a set of demand difference models based on individual responses to questions about seafood consumption in the presence of fish kills and with different amounts of information provided about health risks. We use a random-effects Tobit model to control for correlation across each observation and to account for censoring. We find that (i) pfiesteria-related fish kills have a significant negative effect on the demand for seafood even though the fish kills pose no known threat to consumers through sea-food consumption, (ii) seafood consumers are not responsive to expert risk information designed to reassure them that seafood is safe in the presence of a fish kill, and (iii) a mandatory seafood inspection program largely eliminates the welfare loss incurred due to misinformation.pfiesteria, seafood demand, non-market valuation, Resource /Energy Economics and Policy,

Stability of streamwise vortices

A brief overview of some theoretical and computational studies of the stability of streamwise vortices is given. The local induction model and classical hydrodynamic vortex stability theories are discussed in some detail. The importance of the three-dimensionality of the mean velocity profile to the results of stability calculations is discussed briefly. The mean velocity profile is provided by employing the similarity solution of Donaldson and Sullivan. The global method of Bridges and Morris was chosen for the spatial stability calculations for the nonlinear eigenvalue problem. In order to test the numerical method, a second order accurate central difference scheme was used to obtain the coefficient matrices. It was shown that a second order finite difference method lacks the required accuracy for global eigenvalue calculations. Finally the problem was formulated using spectral methods and a truncated Chebyshev series

The Welfare Effects of Pfiesteria-Related Fish Kills in Seafood Markets: A Contingent Behavior Analysis

We use contingent behavior analysis to study the effects of Pfiesteria related fish kills on the demand for seafood in the Mid-Atlantic region. We use a phone-mail-phone survey to look at the effects of various information provision mechanisms used to ameliorate the effects of misinformation regarding fish kills. A set of demand difference models are estimated based on individual responses to multiple questions about seafood consumption with and without fish kills present and with various health risk information treatments. Random effects Tobit models are used to control for the panel nature of responses and natural censoring of the stated responses. We find that 1) Pfiesteria related fish kills have a significant negative effect on the demand for seafood, 2) seafood consumers are nonresponsive to expert risk information designed to reassure consumers that seafood is safe in the presence of a fish kill, and 3) a mandatory seafood inspection program completely eliminates avoidance costs incurred due to misinformation. We estimate that the aggregate avoidance costs incurred in the month immediately following a Pfiesteria related fish kill is $50-$130 million.

Timed Consistent Network Updates

Network updates such as policy and routing changes occur frequently in Software Defined Networks (SDN). Updates should be performed consistently, preventing temporary disruptions, and should require as little overhead as possible. Scalability is increasingly becoming an essential requirement in SDN. In this paper we propose to use time-triggered network updates to achieve consistent updates. Our proposed solution requires lower overhead than existing update approaches, without compromising the consistency during the update. We demonstrate that accurate time enables far more scalable consistent updates in SDN than previously available. In addition, it provides the SDN programmer with fine-grained control over the tradeoff between consistency and scalability.Comment: This technical report is an extended version of the paper "Timed Consistent Network Updates", which was accepted to the ACM SIGCOMM Symposium on SDN Research (SOSR) '15, Santa Clara, CA, US, June 201

The Effectiveness of a Sodium Monofluorophosphate Dentifrice on Dental Hypersensitivity

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/141672/1/jper0038.pd

Challenges in Modelling Live-Weight Change in Grazed Pastures in the Australian Subtropics

In sub-tropical regions there is enormous seasonal, annual and spatial variation in pasture quality and considerable variation in quality between pasture species. The heterogeneous structure of sub-tropical pasture swards means that process based modelling of liveweight change (LWC) is particularly difficult. In response to this complexity LWC has been expressed as a function of the length of the growing season and/or pasture utilization (McKeon et al. 2000), green leaf availability, or pasture availability and climate (Hirata et al. 1993). However, these relationships vary from year to year, often fail when species composition changes, and generally explai