Merging ‘reasoning’ and filtering in a bayesian framework—some sensitivity and optimality aspects

An approach is described how to incorporate knowledge of symbolic/logic character into a conventional framework of noisy observations in dynamical systems. The idea is based on approximating the optimal solution that could theoretically be computed if a complete Bayesian framework were known (and infinite computational power were available). The nature of the approximations, the deviations from optimality and the sensitivity to ad hoc parameters are specifically addressed. This merging of logic and numerics is essential in many problems of adaptation in control and signal processing.     

Design of servo for gyro test table using linear optimum control theory

A control system is designed and implemented for a test table the motion of which is to track the output of a gyroscope. The process to be controlled is governed by a third-order differential equation with an important nonlinearity due to static friction. Representing the friction as an independent random walk yields a dynamic process amenable to design by methods of linear control theory. An existing design program was used to calculate the compensator transfer function which was realized with standard capacitors, resistors, and operational amplifiers. The compensator was installed in the test table and results in excellent closed-loop system performance.     

Lignin gels as a medium in gel permeation chromatography

The preparation of spherical lignin gel beads, based on the crosslinking reaction between epichlorohydrin and kraft lignin (Indulin AT), is described. The lignin gels prepared were found to be an efficient resin in gel permeation chromatography. The separation of polystyrenes in dimethylformamide is described. The resin was found to separate polystyrenes with molecular weights up to 110,000. An inverse linear relationship between log M and elution volume or the partitioning coefficient was established.     

Theory and applications of self-tuning regulators

This paper reviews work on self-tuning regulators. The regulator algorithms, their theory and industrial applications are reviewed. The paper is expository—the major ideas are covered but detailed analysis is given elsewhere.     

Performance modeling of distributed memory architectures

We provide performance models for several primitive operations on data structures distributed over memory units interconnected by a Boolean cube network. In particular, we model single-source and multiple-source concurrent broadcasting or reduction, concurrent gather and scatter operations, shifts along several axes of multidimensional arrays, and emulation of butterfly networks. We also show how the processor configuration, the data aggregation, and the encoding of the address space affect the performance for two important basic computations: the multiplication of arbitrarily shaped matrices and the Fast Fourier Transform. We also give an example of the performance behavior for local matrix operations for a processor with a single path to local memory and a set of processor registers. The analytic models are verified by measurements on the Connection Machine Model CM-2.     

Tumor labeling indices of primary breast cancers and their regional lymph node metastases

BACKGROUND: Tumor labeling index has emerged as a strong predictor of the clinical course of women with breast cancer. This study investigated whether labeling index of primary tumors correlates with labeling indices of concurrent regional node metastases. METHODS: With appropriate written consent, preoperative in vivo infusion of the thymidine analogue 5-bromodeoxyuridine (BrdUrd) was used to label 109 human breast cancers. Labeled S-phase cells were identified immunohistochemically with an antibody specific to DNA-incorporated BrdUrd. Labeling index was the fraction of labeled nuclei in 2000 tumor nuclei. For 30 women, there was sufficient cancer in axillary lymph nodes to compare labeling indices in primary breast cancer and regional lymph node metastases. RESULTS: The 30 women were from 25 to 82 years of age. Tumors were from 1 to 12 cm in size and there were from 1 to 26 positive nodes. Tumor labeling index ranged from 0.1% to 34%, (mean, 11.1%; median, 10.3%) and axillary lymph node metastasis labeling index ranged from 0.1% to 27.7% (mean, 10.8%; median, 10.0%). There was strong correlation between primary tumor labeling index and regional lymph node metastases labeling index (r = 0.82, with 95% confidence interval 0.65-0.91). The correlation persisted within subgroups according to age, tumor size, number of positive nodes, and hormone receptor status. Primary tumor and lymph node metastases labeling indices also had statistically similar relationships with age, level of hormone receptors, tumor size, and number of positive nodes. CONCLUSIONS: Primary tumor and regional node labeling indices correlate strongly; the relationship is not influenced by age, level of hormone receptors, tumor size, or number of positive nodes.     

A theoretical analysis of recursive identification methods

In this paper five different recursive identification methods will be analyzed and compared, namely recursive versions of the least squares method, the instrumental variable method, the generalized least squares method, the extended least squares method and the maximum likelihood method. They are shown to be similar in structure and need of computer storage and time. Making use of recently developed theory for asymptotic analysis of recursive stochastic algorithms, these methods are examined from a theoretical viewpoint. Possible convergence points and their global and local convergence properties are studied. The theoretical analysis is illustrated and supplemented by simulations.     

Oxidation of sulphide in kraft black liquor and green liquor by residual oxygen in flue gas during precarbonation

Kraft black liquor/green liquor was continuously recirculated in a column (diameter 100 mm, height 450 mm) packed with 16-mm polypropylene Pall rings countercurrent to a gas stream containing N2 and O2 (O2–3.7%). The concentration of sulphide in the green liquor was not affected by oxygen in the gas; the latter, however, completely oxidised the sulphide in kraft black liquor over an 8 h recirculation period.