18,462 research outputs found
The Effect of Spatial Variation of the Turbulent Prandtl Number and Calculation Methods for Heat Transfer in High Mach Number Flows
The effect of using various spatial distributions of the turbulent Prandtl number on the predicted surface heat transfer in the numerical simulation of Mach 4 flat plate flow is studied. The spatial distribution of the turbulent Prandtl number is shown to have a small effect on surface heat transfer, hence suggesting that the standard assumption of a constant turbulent Prandtl number is acceptable for high Mach number boundary layer type flows. In addition, a wall-cell control volume technique for computing heat transfer shows superior predictive capacity across the Reynolds number range when compared to the conventional calculation of surface heat transfer. This indicates that typical levels of refinement now used can be considerably relaxed when calculating heat transfer, with substantial savings in computing resources as well as allowing more accurate assessment of hypersonic vehicle heating loads
The complex relationship between weather and dengue virus transmission in Thailand.
Using a novel analytical approach, weather dynamics and seasonal dengue virus transmission cycles were profiled for each Thailand province, 1983-2001, using monthly assessments of cases, temperature, humidity, and rainfall. We observed systematic differences in the structure of seasonal transmission cycles of different magnitude, the role of weather in regulating seasonal cycles, necessary versus optimal transmission "weather-space," basis of large epidemics, and predictive indicators that estimate risk. Larger epidemics begin earlier, develop faster, and are predicted at Onset change-point when case counts are low. Temperature defines a viable range for transmission; humidity amplifies the potential within that range. This duality is central to transmission. Eighty percent of 1.2 million severe dengue cases occurred when mean temperature was 27-29.5°C and mean humidity was > 75%. Interventions are most effective when applied early. Most cases occur near Peak, yet small reductions at Onset can substantially reduce epidemic magnitude. Monitoring the Quiet-Phase is fundamental in effectively targeting interventions pre-emptively
Algebraic properties of generalized Rijndael-like ciphers
We provide conditions under which the set of Rijndael functions considered as
permutations of the state space and based on operations of the finite field
\GF (p^k) ( a prime number) is not closed under functional
composition. These conditions justify using a sequential multiple encryption to
strengthen the AES (Rijndael block cipher with specific block sizes) in case
AES became practically insecure. In Sparr and Wernsdorf (2008), R. Sparr and R.
Wernsdorf provided conditions under which the group generated by the
Rijndael-like round functions based on operations of the finite field \GF
(2^k) is equal to the alternating group on the state space. In this paper we
provide conditions under which the group generated by the Rijndael-like round
functions based on operations of the finite field \GF (p^k) () is
equal to the symmetric group or the alternating group on the state space.Comment: 22 pages; Prelim0
Mesino - Antimesino Oscillations
The phenomenological implications of supersymmetric theories with low scale
supersymmetry breaking and a squark as the lightest standard model superpartner
are investigated. Such squarks hadronize with light quarks, forming sbaryons
and mesinos before decaying. Production of these supersymmetric bound states at
a high energy collider can lead to displaced jets with large negative impact
parameter. Neutral mesino - antimesino oscillations are not forbidden by any
symmetry and can occur at observable rates with distinctive signatures. Stop
mesino - antimesino oscillations would give a sensitive probe of up-type
sflavor violation in the squark sector, and can provide a discovery channel for
supersymmetry through events with a same-sign top-top topology.Comment: 4 pages, 1 figure, LaTe
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