54,584 research outputs found
NASA ground terminal communication equipment automated fault isolation expert systems
The prototype expert systems are described that diagnose the Distribution and Switching System I and II (DSS1 and DSS2), Statistical Multiplexers (SM), and Multiplexer and Demultiplexer systems (MDM) at the NASA Ground Terminal (NGT). A system level fault isolation expert system monitors the activities of a selected data stream, verifies that the fault exists in the NGT and identifies the faulty equipment. Equipment level fault isolation expert systems are invoked to isolate the fault to a Line Replaceable Unit (LRU) level. Input and sometimes output data stream activities for the equipment are available. The system level fault isolation expert system compares the equipment input and output status for a data stream and performs loopback tests (if necessary) to isolate the faulty equipment. The equipment level fault isolation system utilizes the process of elimination and/or the maintenance personnel's fault isolation experience stored in its knowledge base. The DSS1, DSS2 and SM fault isolation systems, using the knowledge of the current equipment configuration and the equipment circuitry issues a set of test connections according to the predefined rules. The faulty component or board can be identified by the expert system by analyzing the test results. The MDM fault isolation system correlates the failure symptoms with the faulty component based on maintenance personnel experience. The faulty component can be determined by knowing the failure symptoms. The DSS1, DSS2, SM, and MDM equipment simulators are implemented in PASCAL. The DSS1 fault isolation expert system was converted to C language from VP-Expert and integrated into the NGT automation software for offline switch diagnoses. Potentially, the NGT fault isolation algorithms can be used for the DSS1, SM, amd MDM located at Goddard Space Flight Center (GSFC)
Seismic analysis of 70 Ophiuchi A: A new quantity proposed
The basic intent of this paper is to model 70 Ophiuchi A using the latest
asteroseismic observations as complementary constraints and to determine the
fundamental parameters of the star. Additionally, we propose a new quantity to
lift the degeneracy between the initial chemical composition and stellar age.
Using the Yale stellar evolution code (YREC7), we construct a series of stellar
evolutionary tracks for the mass range = 0.85 -- 0.93 with
different composition (0.26 -- 0.30) and (0.017 -- 0.023).
Along these tracks, we select a grid of stellar model candidates that fall
within the error box in the HR diagram to calculate the theoretical
frequencies, the large- and small- frequency separations using the Guenther's
stellar pulsation code. Following the asymptotic formula of stellar -modes,
we define a quantity which is correlated with stellar age. Also, we
test it by theoretical adiabatic frequencies of many models. Many detailed
models of 70 Ophiuchi A have been listed in Table 3. By combining all
non-asteroseismic observations available for 70 Ophiuchi A with these
seismological data, we think that Model 60, Model 125 and Model 126, listed in
Table 3, are the optimum models presently. Meanwhile, we predict that the
radius of this star is about 0.860 -- 0.865 and the age is about
6.8 -- 7.0 Gyr with mass 0.89 -- 0.90 . Additionally, we prove that
the new quantity can be a useful indicator of stellar age.Comment: 23 pages, 5 figures, accepted by New Astronom
Asteroseismic study of solar-like stars: A method of estimating stellar age
Asteroseismology, as a tool to use the indirect information contained in
stellar oscillations to probe the stellar interiors, is an active field of
research presently. Stellar age, as a fundamental property of star apart from
its mass, is most difficult to estimate. In addition, the estimating of stellar
age can provide the chance to study the time evolution of astronomical
phenomena. In our poster, we summarize our previous work and further present a
method to determine age of low-mass main-sequence star.Comment: 2 pages, 1 figures, submitted to IAUS25
Comparing two financial crises: the case of Hong Kong real estate markets
Hong Kong is no stranger to bubbles or crisis. During the Asian Financial Crisis(AFC), the Hong Kong housing price index drops more than 50% in less than a year. The same market then experiences the Internet Bubble, the SARS attack, and recently the Global Financial Crisis (GFC). This paper attempts to provide some âstylized factsâ of the real estate markets and the macroeconomy, and follow the event-study methodology to examine whether the markets behave differently in the AFC and GFC, and discuss the possible linkage to the change in government policies (âlearning effectâ) and the flow of Chinese consumers and investors to Hong Kong (âChina factorâ).regime switching, structural change, small open economy, bounded rationality, banking policy
Effects of the complex mass distribution of dark matter halos on weak lensing cluster surveys
Gravitational lensing effects arise from the light ray deflection by all of
the mass distribution along the line of sight. It is then expected that weak
lensing cluster surveys can provide us true mass-selected cluster samples. With
numerical simulations, we analyze the correspondence between peaks in the
lensing convergence -map and dark matter halos. Particularly we
emphasize the difference between the peak value expected from a dark
matter halo modeled as an isolated and spherical one, which exhibits a
one-to-one correspondence with the halo mass at a given redshift, and that of
the associated -peak from simulations. For halos with the same expected
, their corresponding peak signals in the -map present a wide
dispersion. At an angular smoothing scale of , our
study shows that for relatively large clusters, the complex mass distribution
of individual clusters is the main reason for the dispersion. The projection
effect of uncorrelated structures does not play significant roles. The
triaxiality of dark matter halos accounts for a large part of the dispersion,
especially for the tail at high side. Thus lensing-selected clusters
are not really mass-selected. (abridged)Comment: ApJ accepte
Copper Stabilization in Beneficial Use of Waterworks Sludge and Copper-laden Electroplating Sludge for Ceramic Materials
Session 8: Thermal Treatment & Recyclingpublished_or_final_versio
Cognitive behavioural therapy in pain and psychological disorders : towards a hybrid future
Cognitive Behavioural Therapy (CBT) is a form of evidence-based talking therapy that emphasises the importance of behaviour and conscious thoughts in shaping our emotional experiences. As pain becomes increasingly accepted as not only a sensory but also an emotional experience, success in using CBT to treat emotional disorders has resulted in the incorporation of cognitive-behavioural principles into the management of chronic pain. Outcomes of CBT-informed interdisciplinary pain management programmes are modest at best, despite rapid methodological improvements in trial design and implementation. Whilst the field searches for new treatment directions, a hybrid CBT approach that seeks to simultaneously tackle pain and its comorbidities shows promise in optimising treatment effectiveness and flexibility. This article provides a brief description of the core characteristics of CBT and the transformation this therapeutic model has brought to our understanding and management of chronic pain. Current evidence on efficacy of CBT for chronic pain is then reviewed, followed by a critical consideration of the advantages and disadvantages of the new hybrid treatment approach that conceptualises and treats chronic pain in connection with its comorbidities. Recent progress made in the area of pain and insomnia is highlighted as an example to project therapeutic innovations in the near future
SATMC: Spectral Energy Distribution Analysis Through Markov Chains
We present the general purpose spectral energy distribution (SED) fitting
tool SED Analysis Through Markov Chains (SATMC). Utilizing Monte Carlo Markov
Chain (MCMC) algorithms, SATMC fits an observed SED to SED templates or models
of the user's choice to infer intrinsic parameters, generate confidence levels
and produce the posterior parameter distribution. Here we describe the key
features of SATMC from the underlying MCMC engine to specific features for
handling SED fitting. We detail several test cases of SATMC, comparing results
obtained to traditional least-squares methods, which highlight its accuracy,
robustness and wide range of possible applications. We also present a sample of
submillimetre galaxies that have been fitted using the SED synthesis routine
GRASIL as input. In general, these SMGs are shown to occupy a large volume of
parameter space, particularly in regards to their star formation rates which
range from ~30-3000 M_sun yr^-1 and stellar masses which range from
~10^10-10^12 M_sun. Taking advantage of the Bayesian formalism inherent to
SATMC, we also show how the fitting results may change under different
parametrizations (i.e., different initial mass functions) and through
additional or improved photometry, the latter being crucial to the study of
high-redshift galaxies.Comment: 17 pages, 11 figures, MNRAS accepte
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