Disordered asymmetric simple exclusion process: mean-field treatment

We provide two complementary approaches to the treatment of disorder in a fundamental nonequilibrium model, the asymmetric simple exclusion process. Firstly, a mean-field steady state mapping is generalized to the disordered case, where it provides a mapping of probability distributions and demonstrates how disorder results in a new flat regime in the steady state current--density plot for periodic boundary conditions. This effect was earlier observed by Tripathy and Barma but we provide treatment for more general distributions of disorder, including both numerical results and analytic expressions for the width $2\Delta_C$ of the flat section. We then apply an argument based on moving shock fronts to show how this leads to an increase in the high current region of the phase diagram for open boundary conditions. Secondly, we show how equivalent results can be obtained easily by taking the continuum limit of the problem and then using a disordered version of the well-known Cole--Hopf mapping to linearize the equation. Within this approach we show that adding disorder induces a localization transformation (verified by numerical scaling), and $\Delta_C$ maps to an inverse localization length, helping to give a new physical interpretation to the problem.Comment: 13 pages, 16 figures. Submitted to Phys. Rev.

Active control transport design criteria

Vehicle design considerations for active control applications to subsonic transports are examined. Active control is defined along with those functions which are considered in the study of design criteria. The FAA regulations governing transport aircraft design are briefly discussed

Program computes zero lift wave drag of entire aircraft

Computer program computes zero lift wave drag of an entire aircraft including any combination of the wing, body, pods, fins, and carnard. The program computes the external volume of the wing and the axial area distribution of the wing equivalent body

Extreme 18O-enrichment in majorite constrains a crustal origin of transition zone diamonds

The fate of subducted oceanic lithosphere and its role in the planet-scale geochemical cycle is a key problem in solid Earth studies. Asthenospheric and transition zone minerals included in diamond have been interpreted as representing subducted oceanic crust based on inclusion REE patterns and strong 13C depletion of their host diamond (δ13C as low as -23 ‰). This view/explanation, however, has been challenged by alternative interpretations that variable carbon isotopic compositions either result from high temperature fractionation involving carbides, or reflect primordial, unhomogenised mantle reservoirs. Here, we present the first oxygen isotope analyses of inclusions in such ultradeep diamonds – majoritic garnets in diamond from Jagersfontein (South Africa). The oxygen isotope compositions provide unambiguous evidence for derivation of the inclusions from subducted crustal materials. The δ18OVSMOW values of the majorites range from +8.6 ‰ to +10.0 ‰, well outside that of ambient mantle (+5.5 ±0.4 ‰) and indicate that the protoliths were very heavily weathered at relatively low temperatures. When this information is combined with the broadly eclogitic composition of the majoritic garnets, a derivation from subducted sea-floor basalts is implied. Based on the association between the heavy oxygen and light carbon, the light carbon isotope composition cannot relate to deep mantle processes and is also ultimately derived from the crust

Coherent energy migration in solids: Determination of the average coherence length in one‐dimensional systems using tunable dye lasers

The coherent nature of energy propagation in solids at low temperatures was established from the time resolved response of the crystal to short optical pulses obtained from a dye laser (pumped by a nitrogen gas laser). The trapping and detrapping of the energy by shallow defects (x traps) was evident in the spectra and enabled us to extract the coherence length: l≳700 Å=186 molecules for the one‐dimensional triplet excitons of 1,2,4,5‐tetrachlorobenzene crystals at T<4.2° K. This length which clearly exceeds the stochastic random walk limit is related to the thermalization mechanisms in this coupled exciton–trap system, and its magnitude supports the notion that exciton–phonon coupling is responsible for the loss of coherence on very long molecular chains (trap concentration is 1/256 000)

Cold water aquifer storage

A working prototype system is described in which water is pumped from an aquifer at 70 F in the winter time, chilled to a temperature of less than 50 F, injected into a ground-water aquifer, stored for a period of several months, pumped back to the surface in the summer time. A total of 8.1 million gallons of chilled water at an average temperature of 48 F were injected. This was followed by a storage period of 100 days. The recovery cycle was completed a year later with a total of 8.1 million gallons recovered. Approximately 20 percent of the chill energy was recovered

Current fluctuations in stochastic systems with long-range memory

We propose a method to calculate the large deviations of current fluctuations in a class of stochastic particle systems with history-dependent rates. Long-range temporal correlations are seen to alter the speed of the large deviation function in analogy with long-range spatial correlations in equilibrium systems. We give some illuminating examples and discuss the applicability of the Gallavotti-Cohen fluctuation theorem.Comment: 10 pages, 1 figure. v2: Minor alterations. v3: Very minor alterations for consistency with published version appearing at http://stacks.iop.org/1751-8121/42/34200

Effects of digital altimetry on pilot workload

A series of VOR-DME instrument landing approaches was flown in the DC-9 full-workload simulator to compare pilot performance, scan behavior, and workload when using a computer-drum-pointer altimeter (CDPA) and a digital altimeter (DA). Six pilots executed two sets of instrument landing approaches, with a CDPA on one set and a DA on the other set. Pilot scanning parameters, flight performance, and subjective opinion data were evaluated. It is found that the processes of gathering information from the CDPA and the DA are different. The DA requires a higher mental workload than the CDPA for a VOR-DME type landing approach. Mental processing of altitude information after transitioning back to the attitude indicator is more evident with the DA than with the CDPA

Parton distributions

I discuss our current understanding of parton distributions. I begin with the underlying theoretical framework, and the way in which different data sets constrain different partons, highlighting recent developments. The methods of examining the uncertainties on the distributions and those physical quantities dependent on them is analyzed. Finally I look at the evidence that additional theoretical corrections beyond NLO perturbative QCD may be necessary, what type of corrections are indicated and the impact these may have on the uncertainties.</jats:p