Analysis of Multimodal Systems

The estimation of a multimodal linear system whose mode-to-mode transitions are described by a finite-state Markov chain is described. The problem has application in studying separation standards in an air traffic control environment. An optimal solution is formulated which is computationally infeasible. A suboptimal estimator is then derived which closely approximates the optimal estimator. An example is presented to illustrate the technique.     

Two magnetars: SGR 1627–41 and 1E 1547–5408

We describe the results obtained with Target of Opportunity observations of the galactic sources SGR 1627–41 and 1E 1547–5408. These two transients show several similarities supporting the interpretation of Anomalous X-ray Pulsars and Soft Gamma-ray Repeaters as a single class of strongly magnetized neutron stars.     

Modeling the broadband persistent emission of magnetars

In this paper, we discuss our first attempts to model the broadband persistent emission of magnetars within a self-consistent, physical scenario. We present the predictions of a synthetic model that we calculated with a new Monte Carlo 3D radiative code. The basic idea is that soft thermal photons (e.g. emitted by the star surface) can experience resonant cyclotron upscattering by a population of relativistic electrons treated in the twisted magnetosphere. Our code is specifically tailored to work in the ultra-magnetized regime; polarization and QED effects are consistently accounted for, as well different configurations for the magnetosphere. We discuss the predicted spectral properties in the 0.1–1000 keV range, the polarization properties, and we present the model application to a sample of magnetars soft X-ray spectra.     

Molecular spectroscopy of planetary atmospheres

Summary Clearly spectroscopy has already provided considerable insight into the nature of the planetary atmospheres. Several molecular constituents have been positively identified and upper limits have been placed on the abundances of others which are of particular significance in devising planetary models. But, equally clearly, the inadequacy of the spectral data, due to low spectral and/or spatial resolution, renders deductions of abundances, temperatures and pressures very uncertain. With the sole exception of the Martian CO₂ abundance, knowledge of the concentrations of planetary atmospheric constituents is unsatisfactory, and all numbers given must be regarded as only crude estimates. This latter comment applies equally well to the derived temperatures and pressures.What is urgently needed is the development of a reasonably complete theory of line formation in planetary atmospheres. This, coupled with more detailed spectroscopic work, should produce numerical values of atmospheric parameters which can be used with assurance.This work was performed with the aid of NASA Grant NsG-101-61 with funds administered by the University of California.     

An automated test approach for US Air Force fighter engines

In an effort to support the Air Force's new F-22 Fighter aircraft with its dual F119-PW-100 jet engines, a new approach has been taken to realize the benefits of automated jet engine testing. This paper describes an automated test approach that is currently under development and will be used by the Air Force to test the F119 jet engine; It also identifies; the equipment, methods and techniques that are being employed to accomplish this task     

Boeing 777 high lift control system

The Boeing 777 high lift control systems (HLCS), a state-of-the-art microprocessor-based system that provides fly-by-wire control, protection, and built-in-test and maintenance access functions for the leading edge slats and trailing edge flaps drive and actuation systems, is discussed. This system is designed to take advantage of technologically proven concepts as well as judicious application of new concepts in response to market demands, airline customer input, and a thorough review of lessons learned from previous aircraft programs. The purpose of the HLCS, the wing high lift devices it controls, the HLCS components, its three modes of operation, automatic functions, and system failure protections are described. The use of the EASY5 engineering analysis program developed by the Boeing Company to model dynamic systems in both the time and frequency domains for modeling mechanical and hydraulic portions of the high lift system is discussed     

Passive tracking scheme for a single stationary observer

While there are many techniques for bearings-only tracking (BOT) in the ocean environment, they do not apply directly to the land situation. Generally, for tactical reasons, the land observer platform is stationary; but, it has two sensors, visible and infrared, for measuring bearings and a laser range finder (LRF) for measuring range. There is a requirement to develop a new BOT data fusion scheme that fuses the two sets of bearing readings, and together with a single LRF measurement, produces a unique track. This paper first develops a parameterized solution for the target speeds, and then heading, prior to the occurrence of the LRF measurement, when the track is unobservable. At, and after the LRF measurement, a BOT, formulated as a least squares (LS) estimator, then produces a unique LS estimate of the target states. Bearing readings from the other sensor serve as instrumental variables in a data fusion setting to eliminate the bias in the BOT estimator. The result is an unbiased and decentralized data fusion scheme. Results from two simulation experiments have corroborated the theoretical development and show also that the scheme is optimal.