Dynamics of two-actor cooperation-competition conflict models

We present a nonlinear ordinary differential equation model of the conflict between two actors, who could be individuals, groups, or nations. The state of each actor depends on its own state in isolation, its previous state in time, its inertia to change, and the positive feedback (cooperation) or negative feedback (competition) from the other actor. We analytically determined the stability of the critical points of the model and explored its dynamical behavior through numerical integrations and analytical proofs. Some results of the model are consistent with previously observed characteristics of conflicts, and other results make new testable predictions on how the dynamics of a conflict and its outcome depend on the strategies chosen by the actors.     

Axisymmetric peel test for adhesion measurement of polymer coatings

A novel axisymmetric peel test for measuring the adherence of coatings has been developed. The method utilizes a thin elastomeric membrane as a support for an uncured coating. Application of a pressure differential across this membrane brings the coating into contact with the substrate of interest, allowing it to cure while in contact with the substrate. The peel energy of the fully cured coating is determined by the measured peel force and by the geometry at the peeling front. Use of the test is illustrated with a model glassy polyurethane coating on an aluminum substrate. We show that the test is ideally suited for testing the effects of substrate preparation and cure conditions on the resultant coating adhesion. The upper limit on the adhesion strength that we were able to measure was about 50 J/m², a limit that is determined by the tensile strength of the coating. © 2012 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2012     

Toward unified satellite climatology of aerosol properties.: 3. MODIS versus MISR versus AERONET

We use the full duration of collocated pixel-level MODIS-Terra and MISR aerosol optical thickness (AOT) retrievals and level 2 cloud-screened quality-assured AERONET measurements to evaluate the likely individual MODIS and MISR retrieval accuracies globally over oceans and land. We show that the use of quality-assured MODIS AOTs as opposed to the use of all MODIS AOTs has little effect on the resulting accuracy. The MODIS and MISR relative standard deviations (RSTDs) with respect to AERONET are remarkably stable over the entire measurement record and reveal nearly identical overall AOT performances of MODIS and MISR over the entire suite of AERONET sites. This result is used to evaluate the likely pixel-level MODIS and MISR performances on the global basis with respect to the (unknown) actual AOTs. For this purpose, we use only fully compatible MISR and MODIS aerosol pixels. We conclude that the likely RSTDs for this subset of MODIS and MISR AOTs are ∼73% over land and ∼30% over oceans. The average RSTDs for the combined [AOT(MODIS)+AOT(MISR)]/2 pixel-level product are close to 66% and 27%, respectively, which allows us to recommend this simple blend as a better alternative to the original MODIS and MISR data. These accuracy estimates still do not represent the totality of MISR and quality-assured MODIS pixel-level AOTs since an unaccounted for and potentially significant source of errors is imperfect cloud screening. Furthermore, many collocated pixels for which one of the datasets reports a retrieval, whereas the other one does not may also be problematic.