Comparing the results of an analytical model of the no-vent fill process with no-vent fill test results for a 4.96 cubic meters (175 cubic feet) tank

The NASA Lewis Research Center (NASA/LeRC) have been investigating a no-vent fill method for refilling cryogenic storage tanks in low gravity. Analytical modeling based on analyzing the heat transfer of a droplet has successfully represented the process in 0.034 m and 0.142 cubic m commercial dewars using liquid nitrogen and hydrogen. Recently a large tank (4.96 cubic m) was tested with hydrogen. This lightweight tank is representative of spacecraft construction. This paper presents efforts to model the large tank test data. The droplet heat transfer model is found to over predict the tank pressure level when compared to the large tank data. A new model based on equilibrium thermodynamics has been formulated. This new model is compared to the published large scale tank's test results as well as some additional test runs with the same equipment. The results are shown to match the test results within the measurement uncertainty of the test data except for the initial transient wall cooldown where it is conservative (i.e., overpredicts the initial pressure spike found in this time frame)

Post-processing partitions to identify domains of modularity optimization

We introduce the Convex Hull of Admissible Modularity Partitions (CHAMP) algorithm to prune and prioritize different network community structures identified across multiple runs of possibly various computational heuristics. Given a set of partitions, CHAMP identifies the domain of modularity optimization for each partition ---i.e., the parameter-space domain where it has the largest modularity relative to the input set---discarding partitions with empty domains to obtain the subset of partitions that are "admissible" candidate community structures that remain potentially optimal over indicated parameter domains. Importantly, CHAMP can be used for multi-dimensional parameter spaces, such as those for multilayer networks where one includes a resolution parameter and interlayer coupling. Using the results from CHAMP, a user can more appropriately select robust community structures by observing the sizes of domains of optimization and the pairwise comparisons between partitions in the admissible subset. We demonstrate the utility of CHAMP with several example networks. In these examples, CHAMP focuses attention onto pruned subsets of admissible partitions that are 20-to-1785 times smaller than the sets of unique partitions obtained by community detection heuristics that were input into CHAMP.Comment: http://www.mdpi.com/1999-4893/10/3/9

Two- and three-dimensional viscous computations of a hypersonic inlet flow

The three-dimensional parabolized Navier-Stokes code has been used to investigate the flow through a Mach 7.4 inlet. A two-dimensional parametric study of grid resolution, turbulence modeling and effect of gamma has been done and compared with experimental results. The results show that mesh resolution of the shock waves, real gas effects and turbulence length scaling are very important to get accurate results for hypersonic inlet flows. In addition a three-dimensional calculation of the Mach 7.4 inlet has been done on a straight sideplate configuration. The results show that the glancing shock/boundary layer interaction phenomena causes significant three-dimensional flow in the inlet

OPERATIONAL EFFICIENCY OF A U.S./CANADIAN WHEAT POOL: A GAME THEORY ANALYSIS

The problem of declining wheat prices and excess supply has been the subject of recent economic studies partly because it coincides with the Federal Agriculture Improvement and Reform (FAIR) Act of 1996, and partly because efforts to decrease supply domestically have led to increased imports from Canada. This paper develops a game theory optimization model of market efficiency and derives conditions under which voluntary pooling is sustained for U.S./Canadian durum and hard red spring wheat producers. Analysis reveals that U.S. and Canadian farmers can increase farm returns with efficiency gains from pooling and by internalizing benefits from grain blending and logistics. The model is used to analyze diverse factors affecting the sustainability of such a pool.Voluntary pooling, game theory, efficiency gains, durum and HRS wheat marketing, Crop Production/Industries, Marketing,

Open Research Projects and Public Sociology: Students Communicating Creatively in the Classroom and Beyond

As teachers, we often deny students the freedom to choose topics of inquiry and methods of communication. We have developed an open research project that challenges students to identify a social problem, gather research, and apply what they have learned by targeting an audience and developing a strategy for effective communication. This assignment centers a “problem-posing” focus that tasks students with confronting relevant issues in their lives and communities. It emphasizes public sociology by shifting the audience for their projects from instructors to classmates, families, communities, and beyond. Students have communicated their work through a variety of mediums, including children’s books, videos, poetry, photojournalism, and other artistic formats. We discuss challenges and strategies involved with this open project. Paradoxically, we have learned from this project that lots of freedom requires lots of structure. We find that for students to create high-quality public sociology, teachers must commit to providing clear expectations, deadlines, communication, and accountability