3,161 research outputs found
Scalar gain interpretation of large order filters
A technique is developed which demonstrates how to interpret a large fully-populated filter gain matrix as a set of scalar gains. The inverse problem is also solved, namely, how to develop a large-order filter gain matrix from a specified set of scalar gains. Examples are given to illustrate the method
Pechukas-Yukawa approach to the evolution of the quantum state of a parametrically perturbed system
We consider the evolution of a quantum state of a Hamiltonian which is
parametrically perturbed via a term proportional to the adiabatic parameter
\lambda (t). Starting with the Pechukas-Yukawa mapping of the energy
eigenvalues evolution on a generalised Calogero-Sutherland model of 1D
classical gas, we consider the adiabatic approximation with two different
expansions of the quantum state in powers of d\lambda/dt and compare them with
a direct numerical simulation. We show that one of these expansions (Magnus
series) is especially convenient for the description of non-adiabatic evolution
of the system. Applying the expansion to the exact cover 3-satisfability
problem, we obtain the occupation dynamics which provides insight on the
population of states.Comment: 12 pages, 6 figure
Interaction Energies for the H-H (sub 2) and H (sub 2) - H (sub 2) System
Interaction energies for the H-H (sub 2) and H (sub 2) - H (sub 2) systems have been obtained by a semi-empirical perfect-pairing procedure used previously. The results have been compared with interaction energies obtained from other sources and the agreement among the different curves is reasonably good. A brief discussion of the previous applications of this semi-empirical scheme to other systems is included
An automated method of tuning an attitude estimator
Attitude determination is a major element of the operation and maintenance of a spacecraft. There are several existing methods of determining the attitude of a spacecraft. One of the most commonly used methods utilizes the Kalman filter to estimate the attitude of the spacecraft. Given an accurate model of a system and adequate observations, a Kalman filter can produce accurate estimates of the attitude. If the system model, filter parameters, or observations are inaccurate, the attitude estimates may be degraded. Therefore, it is advantageous to develop a method of automatically tuning the Kalman filter to produce the accurate estimates. In this paper, a three-axis attitude determination Kalman filter, which uses only magnetometer measurements, is developed and tested using real data. The appropriate filter parameters are found via the Process Noise Covariance Estimator (PNCE). The PNCE provides an optimal criterion for determining the best filter parameters
The decontamination of radioactive ion exchange resins using neutral salts as elutriants
Includes bibliographical references (leaves 124-126
Development of utility system simulation model
"Worked preformed for Commonwealth Edison Company, Chicago, Illinois."Includes bibliographical references (leaf 28)MIT DSR Project 7210
The anatomy of exhumed river-channel belts: Bedform to belt‐scale river kinematics of the Ruby Ranch Member, Cretaceous Cedar Mountain Formation, Utah, USA
Many published interpretations of ancient fluvial systems have relied on observations of extensive outcrops of thick successions. This paper, in contrast, demonstrates that a regional understanding of palaeoriver kinematics, depositional setting and sedimentation rates can be interpreted from local sedimentological measurements of bedform and barform strata. Dune and bar strata, channel planform geometry and bed topography are measured within exhumed fluvial strata exposed as ridges in the Ruby Ranch Member of the Cretaceous Cedar Mountain Formation, Utah, USA. The ridges are composed of lithified stacked channel belts, representing at least five or six re‐occupations of a single‐strand channel. Lateral sections reveal well‐preserved barforms constructed of subaqueous dune cross‐sets. The topography of palaeobarforms is preserved along the top surface of the outcrops. Comparisons of the channel‐belt centreline to local palaeotransport directions indicate that channel planform geometry was preserved through the re‐occupations, rather than being obscured by lateral migration. Rapid avulsions preserved the state of the active channel bed and its individual bars at the time of abandonment. Inferred minimum sedimentation durations for the preserved elements, inferred from cross‐set thickness distributions and assumed bedform migration rates, vary within a belt from one to ten days. Using only these local sedimentological measurements, the depositional setting is interpreted as a fluvial megafan, given the similarity in river kinematics. This paper provides a systematic methodology for the future synthesis of vertical and planview data, including the drone‐equipped 2020 Mars Rover mission, to exhumed fluvial and deltaic strata
Airframe Noise Modeling Appropriate for Multidisciplinary Design and Optimization
A Trailing Edge Noise Metric has been developed for constructing response surfaces that may be used for optimization problems involving aerodynamic noise from a clean wing. The modeling approach includes a modified version of a theoretical trailing edge noise prediction and utilizes a high fidelity CFD (RANS) code with a two-equation turbulence model to obtain the characteristic velocity and length scales used in the noise model. The noise metric is not the absolute value of the noise intensity, but an accurate relative noise measure as shown in the validation studies. Parametric studies were performed to investigate the effect of the wing geometry and the lift coefficient on the noise metric. 2-D parametric studies were done using two subsonic (NACA0012 and NACA0009) and two supercritical (SC(2)-0710 and SC(2)-0714) airfoils. The EET Wing (a generic conventional transport wing) was used for the 3-D study. With NACA 0012 and NACA 0009 airfoils, a reduction in the trailing edge noise was obtained by decreasing the lift coefficient and the thickness ratio, while increasing the chord length to keep the same lift at a constant speed. Supercritical airfoil studies showed that decreasing the thickness ratio may increase the noise at high lift coefficients while a reduction may be obtained at low lift coefficients. Both 2-D and 3-D studies demonstrated that the trailing edge noise remains almost constant at low lift coefficients and gets larger at high lift coefficients. The increase in the noise metric can be dramatic when there is significant flow separation. Three-dimensional effects observed in the EET Wing case indicate the importance of calculating the noise metric with a characteristic velocity and length scale that vary along the span
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