Trajectory control of controlled-PM linear synchronous motor magnetic levitation vehicle—FEM dynamics simulations and experiments in mass-reduced-control mode

A novel magnetic levitation train system can be constructed by using a long-stator controlled-PM linear synchronous motor having propulsion and attractive-mode levitation functions and minimum loss. Realizing this system requires simplifying manufacture of the long-stator guideway. In the long-stator on the ground, semiclosed large slots are adapted and designed for one-turn coils of a waveform to be easily installed. The large slots cause the PM LSM detent forces to give strong influences on dynamic operations of the running vehicle. A two-dimensional FEM used for the dynamics simulations is capable of precisely analyzing the detent forces produced between the stator teeth and the PMs. This paper presents FEM dynamics simulations and experiments in mass-reduced-control mode of a 1/2 scale model magnetic levitation vehicle supported by small rubber rollers. The simulation model developed here includes the vehicle speed performance, position sensors and drag force due to friction between rubber roller and rail. The detent force problem in propulsion motion is successfully solved by adapting the feedback control of the vehicle propulsion based on the I₁₀-controlled method. The trajectory control is thus accomplished for the vehicle to follow speed and position patterns. The dynamics simulations are verified from the experiments. The simulation program proposed here enables us to investigate the magnetic levitation train system, including LSM design and vehicle dynamic operations.     

Swelling of hydrophilic polymers. II

The swelling of five types of Sephadex that are either nonionic (G) or possess one of four different ionic groups [sodium carboxymethyl (CM), sodium sulfopropyl (SP), diethyl-aminoethyl chloride (DEAE), diethyl - (2-hydroxypropyl) aminoethyl chloride (QAE)] in the same skeleton of the molecule has been studied by picture analysis and by calorimetry. Inducing dissociation of the ionic group in the polymer skeleton increased the water swelling. By the addition of sodium chloride, the maximum swelling volume of nonionic Sephadex was only slightly decreased. However, that of ionic polymers was considerably decreased. The variation of the apparent first-order rate constant of the swelling and that of the maximum swelling volume show the same tendency. The maximum heats of swelling were 93.2 ± 7.1 J g^?1 for G, 128.8 ± 9.1 J g^?1 for CM, 92.3 ± 8.0 J g^?1 for SP, 68.8 ± 10.5 J g^?1 for DEAE, and 67.0 ± 7.2 J g^?1 for QAE and did not depend on the concentration of sodium chloride. From the results obtained, we conclude that the nonionic Sephadex swells only by hydration but that ionic Sephadexes swell mainly by the osmotic pressure due to the counterions of the ionic groups and that the swelling ratio is not dependent on the kinds of ions but on the ionic concentration. Most of the water in the gels of ionic Sephadexes is free water that does not interact with the Sephadexes. © 1993 John Wiley & Sons, Inc.     

Application of deaerated water in swelling of cellulose and amylose and cotton desizing with enzyme

The effect of deaerated water on the swelling of cellulose and amylose and on the application in cotton desizing with enzyme that contains necessarily these swelling processes were studied. The total volume changes of the swelling of cellulose and amylose were measured by dilatometry. The total volume changes of cellulose and amylose were more negative in deaerated water. In deaerated water, the total volume changes are 142 ± 6% for cellulose and 229 ± 2% for amylose to those in air‐present water. The rates of cotton desizing with two kinds of enzymes were studied by measuring the concentration of generated sugars by using HPLC. Higher efficiency of 140–150% was obtained in deaerated water than in water containing dissolved gases of air, oxygen, or nitrogen. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 1693–1700, 1999     

Communications of the American Ceramic Society Estimation of Thermochemical Data for Calcium Silicate Hydrate (C-S-H)

Calcium silicate hydrate (C-S-H) can be viewed as a solid solution, 0.833Ca(OH)₂.SiO₂.0.917H₂O-xCa(OH)₂, at equilibrium at 30°C. On this basis, the change in Gibbsfree energy (ΔG_r) in the solid-solution reaction was calculated from solubility duta for C-S-H in water. The change in ΔG_r with real ratio decreased notably for the higher calcium contents (CaO/Si0₂1.7; ×0.867). Thermochemical values for C-S-H (CaO/SiO₂=1.7) were estimated to be ΔH°=-2890 kJ/mol, ΔG°=-2630 kJ/mol, and S°=200 J1/mol.K at 298 K .     

Visual search in natural scenes explained by local color properties

Success in visually searching for a small object or target in a natural scene depends on many factors, including the spatial structure of the scene and the pattern of observers' eye movements. The aim of this study was to determine to what extent local color properties of natural scenes can account for target-detection performance. A computer-controlled high-resolution color monitor was used to present images of natural scenes containing a small, randomly located, shaded gray sphere, which served as the target. Observers' gaze position was simultaneously monitored with an infrared video eye-tracker. About 60% of the adjusted variance in observers' detection performance was accounted for by local color properties, namely, lightness and the red-green and blue-yellow components of chroma. A similar level of variance was accounted for by observers' fixations. These results suggest that local color can be as influential as gaze position in determining observers' search performance in natural scenes.     

How temporal cues can aid colour constancy

Colour constancy assessed by asymmetric simultaneous colour matching usually reveals limited levels of performance in the unadapted eye. Yet observers can readily discriminate illuminant changes on a scene from changes in the spectral reflectances of the surfaces making up the scene. This ability is probably based on judgements of relational colour constancy, in turn based on the physical stability of spatial ratios of cone excitations under illuminant changes. Evidence is presented suggesting that the ability to detect violations in relational colour constancy depends on temporal transient cues. Because colour constancy and relational colour constancy are closely connected, it should be possible to improve estimates of colour constancy by introducing similar transient cues into the matching task. To test this hypothesis, an experiment was performed in which observers made surface-colour matches between patterns presented in the same position in an alternating sequence with period 2 s or, as a control, presented simultaneously, side-by-side. The degree of constancy was significantly higher for sequential presentation, reaching 87% for matches averaged over 20 observers. Temporal cues may offer a useful source of information for making colour-constancy judgements.     

Characteristics of color memory for natural scenes

To study the characteristics of color memory for natural images, a memory-identification task was performed with differing color contrasts; three of the contrasts were defined by chromatic and luminance components of the image, and the others were defined with respect to the categorical colors. After observing a series of pictures successively, subjects identified the pictures using a confidence rating. Detection of increased contrasts tended to be harder than detection of decreased contrasts, suggesting that the chromaticness of pictures is enhanced in memory. Detecting changes within each color category was more difficult than across the categories. A multiple mechanism that processes color differences and categorical colors is briefly considered.