26,801 research outputs found
The statistical mechanics of the two-dimensional hydrogen-bonding self-avoiding walk including solvent effects
A two-dimensional square-lattice model for the formation of secondary
structures in proteins, the hydrogen-bonding model, is extended to include the
effects of solvent quality. This is achieved by allowing
configuration-dependent nearest-neighbour interactions. The phase diagram is
presented, and found to have a much richer variety of phases than either the
pure hydrogen-bonding self-avoiding walk model or the standard -point
model.Comment: 23 pages 15 figure
Universality of collapsing two-dimensional self-avoiding trails
Results of a numerically exact transfer matrix calculation for the model of
Interacting Self-Avoiding Trails are presented. The results lead to the
conclusion that, at the collapse transition, Self-Avoiding Trails are in the
same universality class as the O(n=0) model of Blote and Nienhuis (or
vertex-interacting self-avoiding walk), which has thermal exponent ,
contrary to previous conjectures.Comment: Final version, accepted for publication in Journal of Physics A; 9
pages; 3 figure
Single polymer gating of channels under a solvent gradient
We study the effect of a gradient of solvent quality on the coil-globule
transition for a polymer in a narrow pore. A simple self-attracting
self-avoiding walk model of a polymer in solution shows that the variation in
the strength of interaction across the pore leads the system to go from one
regime (good solvent) to the other (poor solvent) across the channel. This may
be thought analogous to thermophoresis, where the polymer goes from the hot
region to the cold region under the temperature gradient. The behavior of short
chains is studied using exact enumeration whilst the behavior of long chains is
studied using transfer matrix techniques. The distribution of the monomer
density across the layer suggests that a gate-like effect can be created, with
potential applications as a sensor.Comment: 5 Pages, 7 Figures, Accepted in Phys. Rev. E (2013
Flight-test measurement of the noise reduction of a jet transport delayed flap approach procedure
A delayed flap approach procedure was flight tested using the NASA CV-990 airplane to measure and analyze the noise produced beneath the flight path. Three other types of landing approaches were also flight tested to provide a comparison of the noise reduction benefits to the delayed flap approach. The conventional type of approach was used as a baseline to compare the effectiveness of the other approaches. The decelerating approach is a variation of the delayed flap approach. A detailed comparison of the ground perceived noise generated during the approaches is presented. For this comparison, the measured noise data were normalized to compensate for variations in aircraft weight and winds that occurred during the flight tests. The data show that the reduced flap approach offers some noise reduction, while the delayed flap and decelerating approaches offer significant noise reductions over the conventional approach
Variable mixer propulsion cycle
A design technique, method and apparatus are delineated for controlling the bypass gas stream pressure and varying the bypass ratio of a mixed flow gas turbine engine in order to achieve improved performance. The disclosed embodiments each include a mixing device for combining the core and bypass gas streams. The variable area mixing device permits the static pressures of the core and bypass streams to be balanced prior to mixing at widely varying bypass stream pressure levels. The mixed flow gas turbine engine therefore operates efficiently over a wide range of bypass ratios and the dynamic pressure of the bypass stream is maintained at a level which will keep the engine inlet airflow matched to an optimum design level throughout a wide range of engine thrust settings
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