Control engineering is a discipline that has in part been driven by practice, in part by theory. The earliest drivers were applications problems in the field of time measurement, mills and steam engine speed control. Major control tasks included control with zero steady state error, and achieving fast response to a step change, without instability or excessive overshoot. Work late in the 19th century provided the first formal solution to the stability problem, and an understanding of the value of integral control. A seventh order water turbine system had been successfully, and scientifically, controlled, by 1900.
In the first half of the 20th century, electronic amplifier design and then the second world war gave much impetus to the development of control engineering. The methods developed for design were predominantly graphical, and involved adjustment of only a few parameters. The role of high gain, proportional, integral and derivative control all became understood and control engineering ideas found applications throught chemical and mineral industries.
Theoretical developments in the second half of this century have been substantial. Many took some years to be translated into practice, such as LQG design, adaptive control and sampled data control. Aerospace applications requirements drove some of these developments, many of which are now finding their place also in materials processing and handling systems, as diverse as sugar cane mills and chemical process control.
Future developments will arise from applications pressure, and theoretical work. Applications pressure is strong in the areas of robotics, automobiles, discrete-event systems, environmental control ; replacement of existing nonadaptive by adaptive systems will be widespread. Theoretical developments will occur in many areas including nonlinear systems, robust control design and, perhaps, use of time-varying controllers for time-invariant plants.

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The wave nature of an electron beam can now be employed to investigate microscopic structures of materials by the development of a “coherent” fieldemission electron beam.

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High Tc superconuctors have the perovskite-related structure with copper ions on B sites, and possess large oxygen nonstoichiometry. The critical temperature is shown to have a close relationship with the oxygen nonstoichiometry. From the relationship between high temperature conductivity and oxygen nonstoichiometry, the carrier concentration and mobility are calculated and compared with those determined by other methods. The valences of copper and bismuth ions are separately determined by the chemical analysis. Contribution of bismuth ions to oxygen nonstoichiometry is shown to be more than copper ions. Detailed study on Ba (Pb_1-xBi_x) O₃ from the viewpoint of defect chemistry indicates that the oxide has large vacancy concentrations of Schottky type.

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Dowa Mining commenced its activity in 1884 with mining Kuroko and have endeavoured to fully utilize underground resources. At first, only silver and small amounts of gold and copper were recovered from Kuroko. With epochmaking research and dovelopment, Dowa Mining succeeded in recovering valuable elements to the greatest extent possible from Kuroko. A large scale of pyritic smelting of Kuroko lump ore was the first epochmaking development. Success separating Kuroko into each concentrate was the next one. The mineral processing technology improved year by year and was accelerated by the development of the ‘hot water flotation’ technology. Smelting processes have changed corresponding with the improvements in the mineral processing results. A Kosaka smelter complex was established to effectively recover valuable metals in other concentrates. A comprehensive network to recover valuable elements in underground resources is described.

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The technical field of non-ferrous metallurgy and the technical correlation between non-ferrous metallurgy and advanced metals will be described.

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In this paper, using the analytical model and calculation procedure proposed by the author, the effects of gas volume and charged gas pressure in the accumulator on the performance of the large-sized hydraulic breaker have been studied, theoretically and experimentally. First, it is confirmed that the theoretical value of pressure drop ratio decreases with increase of the value of effective discharge gas volume inside the accumulator in case of the small-sized breaker, and correlates basically well with these experimental values. This is believed to indicate that these analytical model and method can analyze the accumulator behavior of an actual hydraulic breaker with extraordinary accuracy. In these simulation results, the percussion speed increases with increase of the value of the charged gas pressure within the range of calculation, while the mean supply flow rate decreases. Generally, it is considered that a proper value of the charged gas pressure inside the accumulator is 3.43MPa. However, a value of the percussion speed is almost saturated with Va=0.3l. Accordingly, an appropriate value of gas volume inside the accumulator is 0.3l, and also it should be determined by considering the size of a breaker.

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Split-phase capacitor motors are very available to drive household electric appliances. The motor has some slots and teeth to embed electric conductors or coils. The presence of the slots and teeth introduces the variation ofmagnetic reluctances through the magnetic circuit to produce the pulsation of the air gap flux. Thus the voltage, current and torque of the motor becomes oscillative to increase electric power losses and finally to reduce motor efficiency.
In this study, the non-sinusoidal voltage controlled by a switching element of the triac has been applied to the capacitor motor with wedging the ferrite magnetic material. As the results, the motor efficiency and other characteristics were improved very much. The results obtained have been also verified by the analysis.

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As a first process to prepare high quality strontium ferrite magnet, the uniform mixture of strontium carbonate and hematite particles is necessary. The particles are well dispersed in water if they have high enough same zeta potential. When one has high plus zeta potential and the other has high minus zeta potential at the same pH, their blending caused hetero coagulation, which could form ordered mixture. The uniform wet blended particles by pH control are filtered and then directly calcined. The calcined strontium ferrite, after uniform wet blending by hetero coagulation, showed much higher magnetization than the other ones after dry blending or wet blending at natural pH. Also, the sintered anisotropic strontium ferrite magnet by using pH controlled uniform wet blending, has achieved a little higher (BH) max than the one by using usual dry blending.

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The behavior of the deposited droplet and the movement of the droplet under residual charge on the polymer insulator surface were investigated. It was observed that the deposited droplets after application of voltage tended to move toward the insulator neck. In addition, the distance of the movement toward the insulator neck depends on the applied voltage, the set positions of the droplet and the polarity of the applied voltage. It is suggested that the droplets concentrate around the neck of the polymer insulator so that it might accelerate the wetting process.

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The host material of phosphor Y₂O₃ was processed by the alkoxide hydrolysis and calcination. Monodispersed, spherical yttrium hydroxide particles were obtained in 1-butanol solution at an equivalent concentration of yttrium isopropoxide to water. The diffusion process of precursor to the particle surface was estimated as the rate determining step. The calcination process of yttrium hydroxide to yttria was characterized as a sequence of desorption, decomposition of organics, dehydration, and condensation. The crystallization occurred at temperatures above 500°C.

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General concept of criterion for ductility is presented, and its applications to the prediction for cracking are shown: one is the formability in sheet metal forming as an example of plane stress problem, and the other is the centeral bursting in drawing and extrusion as an expmple of cracking in bulk specimens. Here, the criterion is examined with respect to the collapse of the unique solution. In general, there are two cases bringing about multiplicity: one is statically admissible multiplicity and the other is kinematically admissible multiplicity. After the appearance of statical instability, the strain path cannot be controlled as freely as would be preferred. Ultimately, localized necking occurs when the process satisfies the condition of kinematical instability, the modes of which are consistent with the two modes required from the condition permitting strain rate discontinuity under the continuity of velocity. The general treatment about these criteria and the mode of planes permitting strain rate discontinuity is discussed. Next, two examples for application of the proposed criterion are showm: one is the prediction for the formability of sheet metal, deforming according to the assumed process proceeding from statical instability to kinematical one, and another shows the die angle reduction combination on which a chevron crack occurs in drawing and extrusion under plane strain, where statical instability coincides with kinematical one. These forming limits predicted are compared with several experimental results published in the literature, and they are in very good agreement.

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A new control scheme is proposed in this paper which can cope with varying environment as results of load disturbances, changes of plant dynamics, and failures of components. The objective of this paper is to blend numeric-tosymbolic conversion techniques with linear conventional controllers so as to adapt to the varying environment of the system. The control scheme is based on the parametrization of stabilizing controllers, which is called Kucera/Yula parametrization. The parametrization has been extended to the class of systems which contain numeric-to-symbolic converters. It is shown how the numeric-to-symbolic converters can be blended with the linear controllers.

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Lanthanum and neodymium, light rare-earth elements, have been separated from lanthanum-yttrium and neodymium-gadolinium-yttrium solution, respectively, containing lactic acid or EDTA as a chelator by the electrodialysis. EDTA is so effective in the separation as to be used in most of the experiment. In the lanthanum-yttrium system, the separation factor of lanthanum to yttrium increased with an increase in EDTA concentration, attaining over 100 under the concentrations of complexing ratio higher than 60% and pH 3. The separation fator was also affected by the hydrogen-ion concentration: it increased with increasing pH to the maximum at pH 4. In the neodymium-gadolinium-yttrium system, the separation factor of neodymium to neodmium, gadolinium and yttrium mixture varied with the concentration fraction of neodymium. The separation characteristics were explained by the difference of free-ion (uncomplexed ion) concentrations which was caused by the difference of stability constants for complexes of rare-earth elements.

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The effect of dry grinding by a planetary ball mill on the structures and physical properties of pyrophyllite and talc minerals has been investigated by X-ray diffraction, TG-DTA, density and specific surface area measurements, particle size analysis and SEM observation.
Size reduction of these two minerals was dominated in the early stages of grinding. The obtained fine particles of ground talc and pyrophyllite were subsequently found to aggregate with an increase in grinding time. X-ray diffraction patterns showed that the pyrophyllite and talc structures progressively deformed from a crystalline state to a disordered one with an increase in grinding time. Both ground pyrophyllite and talc specimens exhibit lower temperature dehydroxylation and new exothermic reactions. The ground pyrophyllite recrystallizes to mullite and y -alumina, while the ground talc changes to enstatite and amorphous silica when heated.

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New model of the inhomogeneous layer element is presented for the analysis on a general inhomogeneous elastic layer. Stacking of the new layer elements simulates well a real inhomogeneous layer with small number of the elements. The analytical formulation is made by the transfer matrix method against to the stacked multi-layer structure. Each the stacking layer element is inhomogeneous. Its mechanical impedance varies in linear form with layer thickness.
Applicability of such the new model is inspected with the comparison of the closed form solutions for a linear inhomogeneous layer, with conventional approximate solutions formulated by piling up of many homogeneous layers.

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Usually particles don't behave as individuals but as aggregates or agglomerates in the dense phase of particle assemblage. It doesn't mean a homogeneous continuum but a non-uniform solids body. However, such characteristics have not been investigated extensively yet. Here, the interrelation is systematically dealt with among the packing structure, the stress propagation, the air permeability, and the ultimate strength of compacted powder mass from the original viewpoint of non-uniformity. They all result from compaction which combines the stress with the voidage.

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Recent development on the thermal plasma synthesis techniques for advanced ceramic ultra-fine particles are critically reviewed and mechanisms leading to plasma phase particle formations are proposed. The recommendations for future research direction are discussed in detail.

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High concentration of active grains and low bonding strength are important features for the increase of the removal rate and the reduction of the sub-surface damage in lapping of brittle materials. Thus, high-concentration lapping discs with low bonding strength have been developed.
In this paper, finishing characteristics for various brittle materials were investigated experimentally by using the new lapping discs. A mirror-surface finish of less than 10nmRa was obtained for various brittle materials, and a smooth-surface finish without any dropping-out of grains was achieved for aluminum-nitride substrates.

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Properties and applications of a polymeric gel are reviewed. Thermodynamic models for polymeric gels are also reviewed. The authors particularly described such models as temperature dependence and solvent concentration dependence. Some of reentrant volume phase transition in various fields are introduced. Finally, the results of correlation for volume phase transition of polymeric gels (vinyl alcohol-sodium acrylate copolymer) in aqueous alcohol (methanol, ethanol or propanol) solution are presented.

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