551 research outputs found
Predictability of Top of Descent Location for Operational Idle-Thrust Descents
To enable arriving aircraft to fly optimized descents computed by the flight management system (FMS) in congested airspace, ground automation must accurately predict descent trajectories. To support development of the trajectory predictor and its uncertainty models, commercial flights executed idle-thrust descents at a specified descent speed, and the recorded data included the specified descent speed profile, aircraft weight, and the winds entered into the FMS as well as the radar data. The FMS computed the intended descent path assuming idle thrust after top of descent (TOD), and the controllers and pilots then endeavored to allow the FMS to fly the descent to the meter fix with minimal human intervention. The horizontal flight path, cruise and meter fix altitudes, and actual TOD location were extracted from the radar data. Using approximately 70 descents each in Boeing 757 and Airbus 319/320 aircraft, multiple regression estimated TOD location as a linear function of the available predictive factors. The cruise and meter fix altitudes, descent speed, and wind clearly improve goodness of fit. The aircraft weight improves fit for the Airbus descents but not for the B757. Except for a few statistical outliers, the residuals have absolute value less than 5 nmi. Thus, these predictive factors adequately explain the TOD location, which indicates the data do not include excessive noise
Evaluation of a computer simulation of the radiant heat curing process for primary URD electrical cable
It is the intent of this paper to compare the predictions of an in-house developed computer model, of the radiant heat curing process for plastic insulated electrical cable, with data gathered both from trials in a pilot facility and from actual production in a full scale manufacturing plant. First, background explanations of the product and the manufacturing process are given. Then the thermodynamic and chemical basis of the computer model are discussed in some detail. The model predictions of product temperatures during processing are then compared to the results obtained during trials at the pilot facility. Next, degree of cure data from actual plant production runs is compared to the values generated by the computer model. Finally, conclusions are drawn concerning the overall accuracy of the model predictions and suggestions are made for areas that should be examined if improvement in predictions is desired
Mesoscopic theory for size- and charge- asymmetric ionic systems. I. Case of extreme asymmetry
A mesoscopic theory for the primitive model of ionic systems is developed for
arbitrary size, , and charge, ,
asymmetry. Our theory is an extension of the theory we developed earlier for
the restricted primitive model. The case of extreme asymmetries
and is studied in some detail in a mean-field
approximation. The phase diagram and correlation functions are obtained in the
asymptotic regime and , and for infinite
dilution of the larger ions (volume fraction or less). We find a
coexistence between a very dilute 'gas' phase and a crystalline phase in which
the macroions form a bcc structure with the lattice constant . Such coexistence was observed experimentally in deionized aqueous
solutions of highly charged colloidal particles
Modeling the Bottleneck Process in Electrical Cable Production
This paper addresses the problem of using simulation to model the radiant heat curing process of electrical cable production. The production process for underground residential distribution cable is presented and a simulation model of the bottleneck process is discussed
Ordered Information Systems and Graph Granulation
The concept of an Information System, as used in Rough Set theory, is extended to the case of a partially ordered universe equipped with a set of order preserving attributes. These information systems give rise to partitions of the universe where the set of equivalence classes is partially ordered. Such ordered partitions correspond to relations on the universe which are reflexive and transitive. This correspondence allows the definition of approximation operators for an ordered information system by using the concepts of opening and closing from mathematical morphology. A special case of partial orders are graphs and hypergraphs and these provide motivation for the need to consider approximations on partial orders
Model Energy Landscapes of Low-Temperature Fluids: Dipolar Hard Spheres
An analytical model of non-Gaussian energy landscape of low-temperature
fluids is developed based on the thermodynamics of the fluid of dipolar hard
spheres. The entire excitation profile of the liquid, from the high
temperatures to the point of ideal-glass transition, has been obtained from the
Monte Carlo simulations. The fluid of dipolar hard spheres loses stability when
reaching the point of ideal-glass transition transforming via a first-order
transition into a columnar liquid phase of dipolar chains locally arranged in a
body-centered tetragonal order.Comment: 4 pages, 3 figure
SCOZA for Monolayer Films
We show the way in which the self-consistent Ornstein-Zernike approach
(SCOZA) to obtaining structure factors and thermodynamics for Hamiltonian
models can best be applied to two-dimensional systems such as thin films. We
use the nearest-neighbor lattice gas on a square lattice as an illustrative
example.Comment: 10 pages, 5 figure
Gas-liquid critical point in ionic fluids
Based on the method of collective variables we develop the statistical field
theory for the study of a simple charge-asymmetric primitive model (SPM).
It is shown that the well-known approximations for the free energy, in
particular DHLL and ORPA, can be obtained within the framework of this theory.
In order to study the gas-liquid critical point of SPM we propose the method
for the calculation of chemical potential conjugate to the total number density
which allows us to take into account the higher order fluctuation effects. As a
result, the gas-liquid phase diagrams are calculated for . The results
demonstrate the qualitative agreement with MC simulation data: critical
temperature decreases when increases and critical density increases rapidly
with .Comment: 18 pages, 1 figur
Critical behavior of a fluid in a disordered porous matrix: An Ornstein-Zernike approach
Using a liquid-state approach based on Ornstein-Zernike equations, we study
the behavior of a fluid inside a porous disordered matrix near the liquid-gas
critical point.The results obtained within various standard approximation
schemes such as lowest-order -ordering and the mean-spherical
approximation suggest that the critical behavior is closely related to that of
the random-field Ising model (RFIM).Comment: 10 pages, revtex, to appear in Physical Review Letter
Implementation of the Hierarchical Reference Theory for simple one-component fluids
Combining renormalization group theoretical ideas with the integral equation
approach to fluid structure and thermodynamics, the Hierarchical Reference
Theory is known to be successful even in the vicinity of the critical point and
for sub-critical temperatures. We here present a software package independent
of earlier programs for the application of this theory to simple fluids
composed of particles interacting via spherically symmetrical pair potentials,
restricting ourselves to hard sphere reference systems. Using the hard-core
Yukawa potential with z=1.8/sigma for illustration, we discuss our
implementation and the results it yields, paying special attention to the core
condition and emphasizing the decoupling assumption's role.Comment: RevTeX, 16 pages, 2 figures. Minor changes, published versio
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