Self-tuning control based on generalized minimum variance criterion for auto-regressive models

Theoretical problems on self-tuning control include stability, performance and convergence of the recursive algorithm involved. In this paper, the problem of controlling minimum or non-minimum phase auto-regressive models with constant but unknown parameters is considered. The stability of an algorithm obtained by combining a recursive estimator for the controller parameters and a generalized minimum variance criterion is proved. The main result is the theorem which assures the overall stability for the closed-loop system in presence of white noise in the input-output relation, where the estimated parameters do not necessarily converge to the true values. The algorithm is proved by the Lyapunov theory.     

Recovery of 80 GHz optical clock from 160 Gbit/s data using regeneratively modelocked laser diode

An 80 GHz optical clock signal was successfully recovered from a 160 Gbit/s data stream using a regeneratively modelocking scheme of a semiconductor modelocked laser (MLLD). To handle an 80 GHz electrical signal, the MLLD integrated with a high-mesa electroabsorption modulator and a W-band UTC-PD module are used in this scheme.     

Effects of ventilation and pleural effusion on measurements of airway thermal volume and blood flow in dog lungs

We studied the effects of ventilation and pleural effusion on measurements of airway thermal volume (ATV) and pulmonary blood flow (PBF) by using the airway gas thermometry method of V. B. Serikov, M. S. Rumm, K. Kambara, M. I. Bootomo, A. R. Osmack, and N. C. Staub (J. Appl. Physiol. 72: 944-953, 1992) in 39 anesthetized dogs with or without lung edema or pleural effusion. To examine the differential effects of increased-pressure and increased-permeability lung edema on accuracy and sensitivity of ATV and PBF, two models of lung edema were induced by intravenous infusion of a Dextran 70 solution and alloxan monohydrate, respectively. Dogs were hyperventilated for 3 min by using a wide range of minute ventilation (VE) to produce two steady-state conditions of airway temperature. Higher levels of VE increased an estimated amount of ATV. The ATV produced by hyperventilation at VE values of 559, 158, and 72 ml.min-1.kg-1 was consistent with the gravimetric total lung mass, the blood-free wet lung weight, and the extravascular lung water volume, respectively. The coefficient of lung thermal conductivity, a practical index of the rate of heat conduction through tissue from lung vessels, was related to the ratio of the decrease in expired air temperature to VE, and estimated PBF was consistent with the thermodilution cardiac output. Pleural effusion had little effect on measurements of ATV and PBF. However, ATV and PBF showed increased variation in dogs with dextran-induced lung edema.     

Identification of interleukin-6 producing fibroblastoid cells in cerebrospinal fluid from patients with leukemic meningitis

Differences in the responses of an elderly biracial group of cognitively normal subjects to a 15-item short version of the Boston Naming Test developed for the Consortium to Establish a Registry for Alzheimer's Disease (CERAD) were examined. The subjects consisted of 103 Whites and 136 African Americans who were 70 years of age and older and living in a five-county urban and rural area of North Carolina. They were drawn from the Duke University site of the Established Populations for Epidemiologic Studies of the Elderly (EPESE). All were cognitively normal. With gender, years of education, and age controlled, White subjects performed significantly better than did African American subjects. The items in this test were selected to represent words with a high, medium, and low frequency of occurrence in English. They did not, however, show the expected gradation for either racial group. Medium and low frequency items were of comparable difficulty for the two races. Hierarchical ordering of difficulty would be improved with minor rearrangement of items.     

Electron microscopic study of erythroblastic islands obtained by 'tissue-stamp culture' method

A new 'tissue-stamp culture' method was developed for stamping proliferating erythroblasts of mouse spleens on collagen-coated coverslips after inducing haemolytic anaemia by administration of 1-acetyl-2-phenylhydrazine, and then adherent splenic cells were cultured for a few days. We could obtain many erythroblastic islands, where cultured erythroblasts were located over macrophages and were proliferated synchronously for 10-30 h, and then the erythroblasts were differentiated and enucleated after 30-50 h in the presence of erythropoietin. To observe three-dimensional structures of the erythroblastic islands, a scanning electron microscope was used for the cultured cells treated with critical point-drying method. Immature wrinkled erythroblasts with many micropinocytic pits were attached to the central area of the flattened macrophages with many cytoplasmic projections, though matured erythroblasts were localized on their peripheral areas. Moreover, cytoplasmic projections of underlying macrophages, which were attached to the matured erythroblasts, were decreased in number. At a late stage, deep cytoplasmic invaginations of erythroblasts observed at a middle stage became shallow after their enucleation and flattened to form their concave shapes. This 'tissue-stamp culture' system would be useful for studying specific interaction between stromal macrophages and haematopoietic cells.     

Stochastic analysis of a U-shaped production line with multiple workers

In a conveyor system for mass production as in the Ford system, each station processes just one item in one cycle time, where the cycle time is the time-interval between two successive outputs. In a Just-In-Time production system, a single-unit production and conveyance system is applied to a part production line without conveyors, and multi-function workers and a U-shaped layout of machines have been introduced. The multi-function worker takes charge of multiple machines. In this paper, we consider a U-shaped line with multiple multi-function workers, each of which is responsible for several machines. We formulate it into a marked Petri net, which has a convex property of a generalized semi-Markov process. This shows that the cycle times of two different systems are comparable in the sense of an increasing convex order. We also show the reversibility of the system, that is, the expected cycle time of the reversed system where each worker operates items and walks in the reversed order of stations is the same as that of the original system.     

Cost reduction of polycrystalline diamond compact bits through improved durability

This work reports the results of laboratory drilling tests conducted in order to measure improvements due to design and cutter modifications on PDC bits intended for use in geothermal well drilling. These tests, using 142.88 mm-dia. PDC full face bits, concentrated on improvements in bit life and cost performance. The tests were performed using granite drilling samples and a laboratory drilling machine at atmospheric conditions. The results from changes in bit and cutter shape are reported in the work.