Exponential Mixing for a Stochastic PDE Driven by Degenerate Noise

We study stochastic partial differential equations of the reaction-diffusion type. We show that, even if the forcing is very degenerate (i.e. has not full rank), one has exponential convergence towards the invariant measure. The convergence takes place in the topology induced by a weighted variation norm and uses a kind of (uniform) Doeblin condition.Comment: 10 pages, 1 figur

Economics of Sourcing Cellulosic Feedstock for Energy Production

This study investigates the economics of supplying wheat straw and corn stover within 100 mile radius of a potential new biorefinery in southeast North Dakota. In particular, straw and stover total delivery costs, potential straw and stover supply sites and least cost transportation routes are identified using a linear programming transport model and a GIS (Geographic Information Systems) mapping system. We show that USDA/NRCS (Natural Resources Conservation Service) future crop residue removal rate policies will be important for determining whether it is economically viable to harvest crop residues as potential feedstock for energy generation. Increase in residue removal rates narrow the size of residue supply areas and consequently result in lowering total transportation costs. There is an economic tradeoff between residue collection density and distance from the biorefinery. Most wheat residues are highly concentrated in the north, some distance from the biorefinery. Relying solely on wheat straw for supply needs require longer transportation distances which increases total cost. Using a combination of wheat and corn residues lowers total transportation costs. Since most wheat/corn residues are densely concentrated in north/south, regional highways would likely be the routes used often to transport the residues, as compared to interstate highways. Increased traffic volumes due to the hauling of crop residues would require additional investment in improving road conditions.Wheat Straw, Corn Stover, Density, Transportation Cost, GIS, Community/Rural/Urban Development, Crop Production/Industries,

A Cost-Benefit Analysis of Earned Value Management System Criteria

In December 1996, the Cost/Schedule Control Systems Criteria (C/SCSC) was officially replaced by the Earned Value Management Systems (EVMS) criteria. The switch to EVMS, coupled with current acquisition reform changes, have left many wondering what the effects of these changes will be. This thesis defines the costs and benefits of the old C/SCSC, and then compares them. Additionally, this thesis discusses the changes accompanying the switch to EVMS and the effect on the costs and benefits. The marginal costs of C/SCSC are defined as the difference between the costs of a C/SCSC compliant system and a contractors normal management control system. The marginal system compliance costs are 334-481 person days, while the marginal operating costs are 50% of the C/SCSC compliant operating costs. Fourteen benefits of C/SCSC are detailed in this thesis. The most important benefit discovered was the data reliability that comes with a criteria compliant management control system. The main difference between C/SCSC and EVMS is the system certification process. Under C/SCSC, DoD teams would have to certify a contractor\u27s system. Under EVMS, contractors have the ability to self-certify their system (with final government approval). Cost savings may result through self-certification without reductions in the benefits

Internal waves in the Arctic : influence of ice concentration, ice roughness, and surface layer stratification

Author Posting. © American Geophysical Union, 2018. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research: Oceans 123 (2018): 5571-5586, doi:10.1029/2018JC014096.The Arctic ice cover influences the generation, propagation, and dissipation of internal waves, which in turn may affect vertical mixing in the ocean interior. The Arctic internal wavefield and its relationship to the ice cover is investigated using observations from Ice‐Tethered Profilers with Velocity and Seaglider sampling during the 2014 Marginal Ice Zone experiment in the Canada Basin. Ice roughness, ice concentration, and wind forcing all influenced the daily to seasonal changes in the internal wavefield. Three different ice concentration thresholds appeared to determine the evolution of internal wave spectral energy levels: (1) the initial decrease from 100% ice concentration after which dissipation during the surface reflection was inferred to increase, (2) the transition to 70–80% ice concentration when the local generation of internal waves increased, and (3) the transition to open water that was associated with larger‐amplitude internal waves. Ice roughness influenced internal wave properties for ice concentrations greater than approximately 70–80%: smoother ice was associated with reduced local internal wave generation. Richardson numbers were rarely supercritical, consistent with weak vertical mixing under all ice concentrations. On decadal timescales, smoother ice may counteract the effects of lower ice concentration on the internal wavefield complicating future predictions of internal wave activity and vertical mixing.Seagliders Grant Number: N00014‐12‐10180; Deployment and subsequent analysis efforts of the ITP‐Vs Grant Numbers: N00014‐12‐10799, N00014‐12‐10140; Joint Ocean Ice Studies cruise; Beaufort Gyre Observing System2019-02-1