36,951 research outputs found
Microscopes and computers combined for analysis of chromosomes
Scanning machine CHLOE, developed for photographic use, is combined with a digital computer to obtain quantitative and statistically significant data on chromosome shapes, distribution, density, and pairing. CHLOE permits data acquisition about a chromosome complement to be obtained two times faster than by manual pairing
An abstract specification language for Markov reliability models
Markov models can be used to compute the reliability of virtually any fault tolerant system. However, the process of delineating all of the states and transitions in a model of complex system can be devastatingly tedious and error-prone. An approach to this problem is presented utilizing an abstract model definition language. This high level language is described in a nonformal manner and illustrated by example
An assessment of the real-time application capabilities of the SIFT computer system
The real-time capabilities of the SIFT computer system, a highly reliable multicomputer architecture developed to support the flight controls of a relaxed static stability aircraft, are discussed. The SIFT computer system was designed to meet extremely high reliability requirements and to facilitate a formal proof of its correctness. Although SIFT represents a significant achievement in fault-tolerant system research it presents an unusual and restrictive interface to its users. The characteristics of the user interface and its impact on application system design are assessed
The semi-Markov unreliability range evaluator program
The SURE program is a design/validation tool for ultrareliable computer system architectures. The system uses simple algebraic formulas to compute accurate upper and lower bounds for the death state probabilities of a large class of semi-Markov models. The mathematical formulas used in the program were derived from a mathematical theorem proven by Allan White under contract to NASA Langley Research Center. This mathematical theorem is discussed along with the user interface to the SURE program
The SURE Reliability Analysis Program
The SURE program is a new reliability analysis tool for ultrareliable computer system architectures. The program is based on computational methods recently developed for the NASA Langley Research Center. These methods provide an efficient means for computing accurate upper and lower bounds for the death state probabilities of a large class of semi-Markov models. Once a semi-Markov model is described using a simple input language, the SURE program automatically computes the upper and lower bounds on the probability of system failure. A parameter of the model can be specified as a variable over a range of values directing the SURE program to perform a sensitivity analysis automatically. This feature, along with the speed of the program, makes it especially useful as a design tool
Miniature vibration isolator Patent
Miniature vibration isolator utilizing elastic tubing materia
Uniform saddlepoint approximations for ratios of quadratic forms
Ratios of quadratic forms in correlated normal variables which introduce
noncentrality into the quadratic forms are considered. The denominator is
assumed to be positive (with probability 1). Various serial correlation
estimates such as least-squares, Yule--Walker and Burg, as well as
Durbin--Watson statistics, provide important examples of such ratios. The
cumulative distribution function (c.d.f.) and density for such ratios admit
saddlepoint approximations. These approximations are shown to preserve
uniformity of relative error over the entire range of support. Furthermore,
explicit values for the limiting relative errors at the extreme edges of
support are derived.Comment: Published in at http://dx.doi.org/10.3150/07-BEJ6169 the Bernoulli
(http://isi.cbs.nl/bernoulli/) by the International Statistical
Institute/Bernoulli Society (http://isi.cbs.nl/BS/bshome.htm
Platform-basin transitions and their role in Alpine-style collision systems : a comparative approach
CB acknowledges financial support from Optimus (Aberdeen) ltd. Petroceltic International plc are thanked for providing access to the subsurface data used in this study and for permission to publish images used here. Schlumberger are thanked for providing use of Petrel software under their academic agreement with the University of Aberdeen. RWHB thanks the organisers of the 12th Emile Argand Conference on Alpine Geological Studies for the invitation and financial support to participate in the Montgenevre workshop. Reviewers Enrico Tavarnelli, Thierry Dumont and editors Christian Sue and Stefan Schmid are all thanked for their comments that have significantly improved this contribution.Peer reviewedPublisher PD
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