Power law noise identification using the LAG 1 autocorrelation by overlapping samples
There are various random errors in the fiber optical gyroscope (FOG) output signal. At the aim of improving its accuracy, it is need to identify the kinds of errors. The most common method for power law noise identification is simply to observe the slope of a log-log plot of the Allan or modified Allan deviation versus averaging time, either manually or by fitting a line to it. The lag 1 autocorrelation method is a new method for power law noise identification that can determine the dominant noise type for all common noise processes, from phase or frequency data, for all averaging factors, in a consistent and analytic manner. This paper describes an improvement of it by overlapping samples, which improves the confidence of the resulting stability estimate at the expense of greater computational time.
Calculation of Allan variance for the bias test of the ring laser gyros by using the piecewise regression method
On the basis of Allan variance method,the Allan variance for zero drift signal of ring laser gyros(RLG) is calculated.It is the first time that the five coefficients of error source are acquired by using the piecewise regression method.The results show that this method can effectively evaluate the all kinds of noise in RLG's drift test and extremely reduce the difficulty for data analyzing of Allan variance.The error parts in hardware are found.The scheme to improve the performance of RLG is proposed.
Western versus asian types of multiple sclerosis: Immunogenetically and clinically distinct disorders
The polymorphism of HLA‐DRBI, ‐DRB3, and ‐DRB5 genes as well as magnetic resonance images of the brain and spinal cord were studied in 57 Japanese patients with multiple sclerosis (MS). Twenty‐three patients clinically displayed selective involvement of the optic nerve and spinal cord and were classified as having Asian‐type MS. Patients with Asian‐type MS had fewer brain lesions shown gy magnetic resonance imaging, but more gadolinium‐enhanced spinal cord lesions than did patients with Western‐type MS (47% vs 17%). Fruthermore, the DR2‐associated DRBI1501 allele and DRB50101 allele were associated with Western‐type MS (41.2%), but not with either Asian‐type MS (0%) or healthy control subjects (14.2%). Heterogeneity inthe immunogenetic background and in the magnetic resonance imaging features between the two subtypes of MS thus suggests the presence of two etiologically distinct diseases in Asians.