On the design of optimal output feedback control systems†

For a linear control system with quadratic performance index the optimal control takes a feedback form of all state variables. However, if there are some states which are not fed in the control system, it is impossible to obtain the optimal feedback control by using the usual mathematical optimization technique such as dynamic programming or the maximum principle.

This paper presents the optimal control of output feedback systems for a quadratic performance index by using a new parameter optimization technique.

Since the optimal feedback gains depend on the initial states in the output feedback control system, two cases where (1) the initial states are known, and (2) the statistical properties of initial states such as mean and covariance matrices are known, are considered here. Furthermore, the proposed method for optimal output feedback control is also applied to sampled-data systems.     

Project Execution Capability, Organizational Know-how and Conglomerate Corporate Growth in Late Industrialization

In many successful late-industrializing countries in the 20thcentury, business groups with operating units in technologicallyunrelated industries have acted as the microeco-nomic agentof growth. This paper explores why this business form has characterizedcountries which industrialized ‘late’, and why thisform succeeded in the early phases of catching up whereas theadvanced-country conglomerate has had an undistinguished performance.The paper uses internal resource-base theories of the firm toexplore the significance of organizational knowledge and resultingincreasing returns in the group form which, even in mature marketsand especially in late industrialization, constitute a sustainablesource of competitiveness. In the case of late industrializationforeign technology acquisition capability became a necessarycondition for corporate success. In the best diversified businessgroups this capability was transformed into organizational knowhow that provided a key resource in the effectiveness of corporategrowth through diversification. The first two parts of the paperbriefly survey diversified industrial groups in historical contextsand then across a broad array of late-industrializing countries.Then the paper considers why diversification was not prevalentamong firms attempting to catch up in earlier historical periods,why the strategy of leading late industrializing firms was oneof diversification rather than specialization and why theirchosen diversification path was one involving technologist collyunrelated industries. This is followed by the core argumentof the paper about the transformation of technology acquisitioninto a competitive asset and illustrated with evidence fromSouth Korea. Finally, the paper analyzes why the behavior ofthe late industrializing group differs from that of the Americanconglomerate.     

High-Temperature Reaction Between Cemented Tungsten Carbide and Copper

Interdiffusion in the system cemented tungsten carbide-molten copper has been studied in the range ≤1120°C with special emphasis on the effects of WC grain size and Co content. Techniques used for analyzing the diffusion layers obtained are EPMA, optical microscopy, and microhardness measurement. A Cu-bonded WC layer develops with simultaneous diffusion of Co from the cemented carbide into the bulk copper. The Cu-bonded WC layer grows until a Co-rich layer forms at the Cu/WC-Co interface; further heating pushes the Cu-bonded WC layer deep into the bulk cemented carbide without any significant change in layer thickness. When the WC grain size is reduced and the cobalt content increased, the penetration of copper into cemented carbides increases. A tentative mechanism of interdiffusion has been proposed based on the experimental results.     

On the estimation of noise covariances in linear discrete-time systems

This paper is concerned with an approach for estimating or tracking the time-varying input and measurement noise covariances in time-varying discrete-time linear systems. The approach is firstly to introduce the estimators for the case where the noise co-variances are unknown constants. (The estimators are defined as the mean squares of the estimators of noises based on all the available measurement data.) They arc then transformed in sequential form, and are subsequently modified by incorporating a fading memory to yield estimates for time-varying noise covariances. The time-varying noise covariance estimates are evaluated as the fading mean squares of the estimates of noises based on all the measurement data up to present time. A numerical example for a simple system indicates acceptable performance of the proposed method.     

Conditions for the delay-independent stabilization and the decay rate assignability of linear systems

In a previous paper (Amemiya 1983) two sufficient conditions were introduced for the delay-independent stabilization of linear systems by means of state-variable feedback including no delays.

In this paper the concept of delay-independently upper or lower bound of decaying rate assignability (DIUDA or DILDA) are introduced and it is proved that the two conditions previously obtained are necessary and sufficient condition for DIUDA and necessary condition for DILDA of linear systems by means of state-variable feedback including no delays. The conditions obtained are also applicable to systems including time-varying delays.     

A STRATEGY FOR THE DEVELOPMENT OF NEW ENERGY TECHNOLOGY IN THE GLOBAL ENVIRONMENT ERA (The Revised Sunshine Project)

The Japanese R & D Programme on solar energy under the Sunshine Project of MITI will be described. The programme is aiming at practical use of solar energy in the 21st century.     

Preparation of Cerium-Activated Silica Glasses: Phosphorus and Aluminum Codoping Effects on Absorption and Fluorescence Properties

Cerium-activated silica (SiO₂) glasses were prepared by plasma torch chemical vapor deposition (CVD). In Ce-doped SiO₂ glasses, most Ce exists as Ce⁴⁺ ions; the remaining small amount of Ce³⁺ ions exhibits a broad fluorescence spectrum with a large Stokes shift, ∼9600 cm^-1, from the excitation spectrum peak of 324 nm. Aluminum and phosphorus codoping considerably increases the Ce³⁺ ratio and shifts the peaks of both spectra to shorter wavelengths. P codoping is the more effective way to achieve this result and in some cases produces an absorption spectrum similar to that of a Ce-doped phosphate glass. These findings are consistent with the solvatiorn shell model for codoping, as previously proposed. To codope P, a soot remelting method was devised to deal with the highly volatile P₂O₅.     

Crystallization and Transformation of Distorted Tetragonal YNbO4

Distorted tetragonal YNbO₄ crystallizes from an amorphous material prepared by the simultaneous hydrolysis of yttrium and niobium alkoxides. It can be preserved at room temperature by quenching and has a unit cell with α=0.5164 nm and c= I,0864 nm. The structure contains tetrahedral NbO⁴ groups.     

Odor Components of Human Breath After the Ingestion of Grated Raw Garlic

The major odor components of finely grated, raw garlic in the air of the human mouth have been studied. Immediately after garlic ingestion, tests of the mouth air of six subjects revealed two major peaks that were positively identified as being allyl mercaptan and diallyl disulfide; these findings are based on an evaluation of the fragment patterns of a GC-MS analysis and from the actual retention times of these authentic compounds. The allyl mercaptan level was higher than the level of diallyl disulfide, although both compounds smell like garlic. Our results suggest that after garlic ingestion, allyl mercaptan is the major garlic-smelling compound in human mouth air, and diallyl disulfide is secondary.