Flows in inkjet-printed aqueous rivulets

We used optical microscopy to investigate flows inside water rivulets that were inkjet-printed onto different surfaces and under different ambient conditions. The acquired fluid dynamics videos were submitted to the 2013 Gallery of Fluid Motion.Comment: This article accompanies a fluid dynamics video submitted to the 2013 Gallery of Fluid Motion of the 66th Annual Meeting of the APS Division of Fluid Dynamic

Superconvergent interpolatory HDG methods for reaction diffusion equations I: An HDGk_{k} method

In our earlier work [8], we approximated solutions of a general class of scalar parabolic semilinear PDEs by an interpolatory hybridizable discontinuous Galerkin (Interpolatory HDG) method. This method reduces the computational cost compared to standard HDG since the HDG matrices are assembled once before the time integration. Interpolatory HDG also achieves optimal convergence rates; however, we did not observe superconvergence after an element-by-element postprocessing. In this work, we revisit the Interpolatory HDG method for reaction diffusion problems, and use the postprocessed approximate solution to evaluate the nonlinear term. We prove this simple change restores the superconvergence and keeps the computational advantages of the Interpolatory HDG method. We present numerical results to illustrate the convergence theory and the performance of the method

A Class of Embedded DG Methods for Dirichlet Boundary Control of Convection Diffusion PDEs

We investigated an hybridizable discontinuous Galerkin (HDG) method for a convection diffusion Dirichlet boundary control problem in our earlier work [SIAM J. Numer. Anal. 56 (2018) 2262-2287] and obtained an optimal convergence rate for the control under some assumptions on the desired state and the domain. In this work, we obtain the same convergence rate for the control using a class of embedded DG methods proposed by Nguyen, Peraire and Cockburn [J. Comput. Phys. vol. 302 (2015), pp. 674-692] for simulating fluid flows. Since the global system for embedded DG methods uses continuous elements, the number of degrees of freedom for the embedded DG methods are smaller than the HDG method, which uses discontinuous elements for the global system. Moreover, we introduce a new simpler numerical analysis technique to handle low regularity solutions of the boundary control problem. We present some numerical experiments to confirm our theoretical results

Validating the Substance Abuse Subtle Screening Inventory for Identifying Substance Abuse Among Adolescents in a Residential Treatment Center

Purpose. This study examines the construct validity of the Substance Abuse Subtle Screening Inventory for Adolescents (SASSI-A) as a substance-abuse screening instrument for dual-diagnosed adolescents in a residential treatment center. Method. Using archival records of 336 subjects from a long-term residential treatment center, this study applied a two-group comparison method to examine the construct validity of the SASSI-A for screening substance abuse among adolescents in a residential treatment center. Residents were initially clinically assessed by a state certified counselor as either substance abuser/chemically dependent or non-substance abuser/chemically dependent. At this residential treatment center, the clinical assessment included a full review of the resident\u27s clinical and medical file, consult with the resident\u27s family if possible, welfare and/or probation staff, the primary therapist and other residential staff, and an assessment interview. Scale scores and decision rules for the SASSI-A were then compared to the classification by clinical assessment. Underlying structure of the SASSI-A was also examined through principal component analysis. Results. Independent t tests for the SASSI-A subscales scores showed significant differences in the mean scores between those clinically assessed as substance abuser/chemically dependent and those who were not. Those who were classified as chemically dependent using SASSI-A Decision Rules #1, #2, #3, and #4 were also likely to be clinically assessed as substance abuser/chemically dependent. For this sample, there was insufficient remaining subjects to test the utility of Decision Rules #5 and #6. Classification by clinical assessment and by SASSI-A was unrelated to demographic variables. In comparing the end results of the SASSI-A Decision Rules classification versus the results of those clinically assessed, there was an overall classification agreement of 78.6%. Principle component analysis with varimax rotation resulted in three meaningful underlying factors. Conclusions. Compared to classification by clinical assessment, the SASSI-A appears to be a valid screening instrument for identifying substance abuse/chemical dependency among adolescents in a residential treatment center