The effect of channel convergence on heat transfer in a passage with short pin fins

Array averaged heat transfer coefficients were obtained for two configurations of short pin fins in a converging channel and for two flat plate configurations in a converging channel. The effect of flow acceleration due to channel convergence and the effect of varying pin length on the heat transfer was determined. Results are presented in the form of Nusselt number versus Reynolds number for the four geometries tested

Fitness Norms for the Plank Exercise

PURPOSE: Adequate strength of core musculature is critical for optimal physical performance and postural control. Currently, standards for core musculature strength and stability have not been established. This study sought to determine normative fitness measurements of core musculature endurance using the plank exercise. METHODS: 168 collegiate male and female participants (18-25 years of age) were recruited. Participants were instructed in plank positioning; elbows bent at 90° directly below the shoulders, hands unclasped, feet placed hip width apart with ankles at 90° and pelvis tilted in the neutral position. After a 5-minute warm-up, participants were told to maintain the plank position as long as possible until complete fatigue was reached. The test was terminated if proper form was broken. The total time held in proper plank position was recorded. RESULTS: The mean time held in the plank position was 96.25 + 43.16 and 116.58 + 65.49 seconds for females and males, respectively. For females, quartiles showed that the 25th percentile was 63 seconds, the 50th percentile was 90 seconds, while the 75th percentile was 121 seconds. Quartiles for males were 77seconds, 106 seconds and 128.5 seconds for the 25th, 50th and 75th percentiles, respectively. CONCLUSION: This study provides normative values for the plank exercise that can be added to current fitness appraisal protocols to assess core muscular endurance. These data suggest that 1.50 minutes in females and 1.77 minutes in males (50th percentile values) could be considered average duration of the plank exercise for this age group

Length to diameter ratio and row number effects in short pin fin heat transfer

The relative effects of pin length to diameter ratio and of pin row geometry on the heat transfer from pin fins, was determined. Array averaged heat transfer coefficients on pin and endwall surfaces were measured for two configurations of staggered arrays of short pin fins (length to diameter ratio of 4). One configuration contained eight streamwise rows of pins, while the other contained only four rows. Results showed that both the 8-row and the 4-row configurations for an L sub p/D of 4, exhibit higher heat transfer than in similar tests on shorter pin fns (L sub p/D of 1/2 and 2). It was also found that for this L sub p/D ratio, the array averaged heat transfer was slightly higher with eight rows of staggered pins than with only four rows

Geothermal reservoir engineering research

The Stanford University research program on the study of stimulation and reservoir engineering of geothermal resources commenced as an interdisciplinary program in September, 1972. The broad objectives of this program have been: (1) the development of experimental and computational data to evaluate the optimum performance of fracture-stimulated geothermal reservoirs; (2) the development of a geothermal reservoir model to evaluate important thermophysical, hydrodynamic, and chemical parameters based on fluid-energy-volume balances as part of standard reservoir engineering practice; and (3) the construction of a laboratory model of an explosion-produced chimney to obtain experimental data on the processes of in-place boiling, moving flash fronts, and two-phase flow in porous and fractured hydrothermal reservoirs

National park research fellowships increase capacity and creativity in responding to climate change

The challenges posed by climate change in national parks and other protected areas demand creative approaches, new ideas, and experiments that are beyond the capacity of any single park or agency staff. Research fellowships provide a critical way that the National Park Service (NPS) and its partners can address the agency’s needs to address climate change adaptation challenges. At least 30 such programs support stewardship-relevant science in national parks. Some national programs and initiatives at Acadia National Park in Maine, Rocky Mountain National Park in Colorado, and Sequoia and Kings Canyon National Parks in California serve as examples of how researchers in these programs are informing restoration, relocation, vegetation and fire management, and resource protection activities; documenting change that has already occurred; providing baseline data on biodiversity; and conducting novel experiments. Successful fellowship programs have strong engagement of resource managers, emphasize communication with management and public audiences, and incorporate ongoing support and evaluation. As a result of these successes, NPS and partners are working to expand and strengthen the sustainability and effectiveness of research grants and fellowships

A General Setting for Geometric Phase of Mixed States Under an Arbitrary Nonunitary Evolution

The problem of geometric phase for an open quantum system is reinvestigated in a unifying approach. Two of existing methods to define geometric phase, one by Uhlmann's approach and the other by kinematic approach, which have been considered to be distinct, are shown to be related in this framework. The method is based upon purification of a density matrix by its uniform decomposition and a generalization of the parallel transport condition obtained from this decomposition. It is shown that the generalized parallel transport condition can be satisfied when Uhlmann's condition holds. However, it does not mean that all solutions of the generalized parallel transport condition are compatible with those of Uhlmann's one. It is also shown how to recover the earlier known definitions of geometric phase as well as how to generalize them when degeneracy exists and varies in time.Comment: 4 pages, extended result

Efficient Global Sensitivity Analysis of Structural Vibration for a Nuclear Reactor System Subject to Nonstationary Loading

The structures associated with the nuclear steam supply system (NSSS) of a pressurized water reactor (PWR) include significant epistemic and aleatory uncertainties in the physical parameters, while also being subject to various non-stationary stochastic loading conditions over the life of a nuclear power plant. To understand the influence of these uncertainties on nuclear reactor systems, sensitivity analysis must be performed. This work evaluates computational design of experiment strategies, which execute a nuclear reactor equipment system finite element model to train and verify Gaussian Process (GP) surrogate models. The surrogate models are then used to perform both global and local sensitivity analyses. The significance of the sensitivity analysis for efficient modeling and simulation of nuclear reactor stochastic dynamics is discussed