Showing papers by "Nagoya Institute of Technology published in 1994"

Estimation, identification, and sensorless control in motion control system

Abstract: The paper presents the state of the art of motion systems particularly emphasizing both estimation and identification of parameters and control variables of an electric-motor-driven motion system. In a modern electrical drive system, it is required to take not only the electrical aspect but also the mechanical phase into total system consideration. Improvement in electrical aspect needs a variety of information pertaining to electrical machines and power electronic circuits for improving AC variable-speed drives. Important techniques of identification or estimation of parameters and control variables in AC drives are explained. Such information includes machine parameters, flux, speed, position, and so on. Also, the paper shows that there is some theoretical limit of performance. For improvement of the mechanical phase, the disturbance torque is the most important variable to be identified. It is used in motion control systems, for example, in the feedback loop. Various applications are possible by modification of such a basic approach. As a conclusion, the paper shows that the total robustness is attained by integrating advances of control technique on the electrical aspect and the mechanical aspect. There are numerous variations of controller by possible combinations of these two aspects according to applications. >

Crystal structures of TiO2 thin coatings prepared from the alkoxide solution via the dip-coating technique affecting the photocatalytic decomposition of aqueous acetic acid

Abstract: TiO2 coatings with different crystal structures were prepared from alkoxide solutions via the dip-coating technique. The physical properties, except the crystal structure, were adjusted to distinguish the effect of crystal structure on their photocatalytic property. The results of photocatalytic measurements using TiO2 coatings with different crystal structures showed that the decomposition of aqueous acetic acid was enhanced by the content of anatase phase.

Microstructure and crystallization behaviour of TiO2 precursor prepared by the sol-gel method using metal alkoxide

Abstract: TiO2 precursors were prepared by the sol-gel method using titanium tetraisopropoxide. The effects of water and hydrochloric acid addition for the hydrolysis and polymerization reaction on the crystal lattice or the molecular structure, and on the crystallization behaviour of prepared precursors, were examined by using Raman, and infrared spectroscopy, X-ray diffraction, DTA-TG and carbon analysis. The quantity of unhydrolysed alkyls in precursors decreased with increasing amounts of H2O and HCl addition, but the alkyls always remained. Raman spectroscopy revealed that the molecular structure of prepared amorphous precursors resembled that of the anatase phase with increased H2O and HCl addition. On the crystallization process of these precursors, the ratio of anatase formed at 310 °C was influenced by residual unhydrolysed alkyls. Steric hindrance by the residual alkyls preventing crystallization to crystalline anatase was observed, and there was estimated to be 2.5 mol of octahedral coordination of Ti-O per 1 mol of residual alkyls. It is noted that crystallization of the anatase phase and the transformation from anatase to the rutile phase were also observed on long-term ageing of precursors at room temperature.

Uptake of a neurotoxin-candidate, (R)-1,2-dimethyl-6,7-dihydroxy-1,2,3,4-tetrahydroisoquinoline into human dopaminergic neuroblastoma SH-SY5Y cells by dopamine transport system.

Abstract: Uptake of catechol isoquinolines to dopamine cells was studied using human dopaminergic neuroblastoma SH-SY5Y cells. Only (R)-1,2-methyl-6,7-dihydroxy-1,2,3,4-tetrahydroisoquinoline [(R)-1,2-DiMeDHTIQ] was transported by dopamine uptake system, while (S)-1,2-DiMeDHTIQ, (R)- and (S)-1-methyl-6,7-dihydroxy-tetrahydroisoquinoline, and 1,2-dimethyl-6,7-dihydroxyisoquinolinum ion were not. Kinetical study showed that the uptake of (R)-1,2-DiMeDHTIQ followed the Michaelis-Menten equation, and the values of the Michaelis constant and the maximal velocity were obtained to be 102.6 +/- 36.9 microM and 66.0 +/- 2.8 pmol/min/mg protein. Dopamine was found to inhibit (R)-1,2-DiMeDHTIQ uptake competitively. These results suggest that the selective uptake by dopamine transporter may account for the specific neurotoxicity of (R)-1,2-DiMeDHTIQ to dopamine neurons.

Linear-Time Snapshot Using Multi-writer Multi-reader Registers

Abstract: We present a wait-free implementation of the atomic snapshot object on the shared memory system. A snapshot object shared by n processes is a data structure partitioned into n segments such that each process owns one segment. Each process can update its own segment, and instantaneously scan all segments. In our implementation, each object operation requires O(n) operations on atomic multi-writer multi-reader registers.

29Si NMR Spectroscopy of Silicate Anions in Hydrothermally Formed C‐S‐H

Abstract: Hydrothermal treatment of lime–silica mixtures under saturated steam pressures below 200°C usually gives C-S-H as an initial product, which reacts further to give crystalline calcium silicate hydrates. In this paper, C-S-H was hydro–thermally prepared using CaO and silicic acid at Ca/Si ratios of 0.3 to 2.0 and 120° to 180°C for 2 h. The C-S-H was examined mainly using 29Si NMR by the magic angle spinning gate proton decoupling and cross polarization magic angle spinning methods. XRD for all of the C-S-H showed bands at 0.304, 0.280, 0.183, and 0.166 nm. NMR results showed that all of the C-S-H contained single chains of silicate anion, which became progressively longer as the Ca/Si ratio decreased, i.e., as the system became richer in silica. This was independent of the preparation temperature. The 0.8 ratio preparations at 180°C contained small amounts of double-chain structure of 1.1-nm tobermorite. The reaction processing in the lime- silicic acid mixtures is also discussed.

A novel starting method of sensorless salient-pole brushless motor

Abstract: Brushless DC motors are receiving much attention for drive application because of their high efficiency, high torque to current ratio and high power density. Among various types of brushless DC motors, the salient-pole brushless motor is attractive from two standpoints: torque/current ratio; and feasibilities of sensorless drive and stable starting without a position sensor. Unlike the conventional cylindrical rotor motor, the salient-pole brushless motor produces additional reluctance torque, which improves the torque/current ratio. In addition to that, the winding inductance is a function of rotor position and a novel approach to rotor position estimation is possible without using a position sensor. The paper presents a sensorless drive of a 2.2 kW salient-pole brushless DC motor and emphasis is placed on stable starting by estimating initial rotor position before starting. To estimate initial rotor position, two types of pilot voltages from an inverter are provided. The pilot voltages are rectangular pulsewise DC voltages with different duties and the resultant current peaks are used to estimate the initial rotor position before starting. The proposed algorithm for initial rotor position identification is verified by simulations and experiments. >

Effects of pH and organic solvent on chromatographic behavior in capillary electrochromatography

Abstract: Electrochromatography is demonstrated using a 50 μm i.d. capillary column. The separation of solutes due to their different mobilities is obtained by the application of high voltage along the column. The elution times of solutes are dependent on the pH and composition of the eluent. Both electrophoretic and electroosmotic flow velocities are almost constant between 30 and 90% methanol in the eluent, and they increase with more than 90% methanol. The pH dependence of the electroosmotic flow velocity may be related to the dissociation of unreacted silanol groups on the surface of the ODS-silica particles.

A sequencing problem for a mixed-model assembly line in a JIT production system

Abstract: In an assembly line of a just-in-time (JIT) production system, workers have the power and the responsibility to stop the line when they fail to complete their operations within their work zones. This paper deals with a sequencing problem for the mixed-model assembly conveyor line in the JIT production system. In some environment, the most important criterion is the line stoppage rather than the variation of production rates. The problem is to find an optimal sequence of units that minimizes the total line stoppage time. Lower and upper bounds of the total line stoppage time are derived and the branch-and-bound method is applied to the problem. A numerical example is given.

Novel toxins and Parkinson’s disease: N-methylation and oxidation as metabolic bioactivation of neurotoxin

Abstract: In human brains, a series of monoamine-derived 1,2,3,4-tetrahydroisoquinolines and the 6,7-dihydroxy derivatives has been identified. A tetrahydroisoquinoline was found to cause parkinsonism in monkey, but its toxicity was not so potent as 1-methyl-4-phenyl-1,2,3,6-tetrahy-dropyridine. Two metabolic steps were found to increase cytotoxicity of isoquinolines. N-Methylation by a non-specific N-methyltransferase was proved by in vivo and in vitro experiments. The N-methylated compound was oxidized into N-methylisoquinolinium ion by monoamine oxidase from human brain mitochondria. The oxidation was proved by microdialysis in the rat brain. The isoquinolinium ion was more cytotoxic than the two metabolic precursors. N-Methylation of dopamine-derived 1-methyl-6,7-dihydroxy-1,2,3,4-tetrahydroisoquinolines was detected by in vivo micro-dialysis in the rat striatum, and their presence in the human brain was confirmed by GC-MS. The metabolic bioactivation may be a general pathway to produce neurotoxins as the pathogenic agents of Parkinson’s disease.

Calcium phosphate precipitation on the surface of HA‐G‐Ti composite under physiologic conditions

Abstract: Hydroxyapatite-glass-titanium (HA-G-Ti) functionally gradient composite plates bound face-to-face by nylon wire were soaked in a simulated body fluid. The gap between the plates was filled with the precipitates after soaking for 6 months, and a tight chemical bond was formed between them. Field emission-type (FE) scanning electron microscopy (SEM) and transmission electron microscopy observations revealed that the growth rate and morphology of the precipitates differed widely from the outside portion to the inside one on the surface region of the composite plates. In the portion relatively near the outside, the mutually bonded portion, needle-like precipitates with preferred orientation to the c-axis were markedly observed. From the results of Fourier transform infrared spectroscopy and energy dispersive x-ray microanalysis, it was found that the precipitates were Ca-deficient carbonate apatite with low crystallinity. On the other hand, HA-G-Ti composite rods were implanted in the femur of beagle dogs for 3 months. FE-SEM observations demonstrated that needle-like precipitates were deposited on both the surfaces of the composite and bone at the portion having a narrow gap, about 0.1–0.2 mm between them prepared deliberately before implantation. It was found that both the morphologies and the composition of the precipitates in vivo were similar to those in vitro. It is concluded that the HA particles on the surface of the composite act as nucleation sites for precipitation in physiologic environments, whereas the glass matrix is independent to it. © 1994 John Wiley & Sons, Inc.

Hydrogen reduction of liquid iron oxide fines in gas-conveyed systems

Abstract: A laboratory scale fine particles-gas conveyed system was utilized to measure the reduction rates of liquid wustite with hydrogen at high temperatures. N2-H2 mixtures having various flow rates and compositions were flowed downward through a cylindrical reactor maintained at a constant temperature of 1723 to 1823 K. A batch of pure spherical wustite particles (mean dia.; 58μm) was concurrently fed into the reactor at a small constant rate and reduced in a hot zone. The reduction process was found to proceed in such a manner that metallic iron particles were enclosed inside a wustite droplet. Rate analysis was made of one dimensional mass balance equations for particle taking the shrinkage into consideration. Under relatively small reducing potentials, it was concluded that the major fraction of overall reaction resistance is attributable to chemical reaction. However, under higher reducing potentials, the reduction process was estimated to include an appreciable diffusion resistance within the liquid phase. >From the temperature dependence of forward chemical reaction rate constants, the activation energy was evaluated to be 110 kJ/mol.

Enzymatic and genetic adaptation of soleus muscle mitochondria to physical training in rats.

Abstract: To evaluate the effects of physical training on mitochondrial gene expression and mitochondrial biogenesis in slow-twitch muscle, adult female Sprague-Dawley rats were trained for 3, 6, and 12 wk b...

MOCVD growth of GaAsP on Si for tandem solar cell application

Abstract: In this paper, the crystal growth of GaAsP on Si substrate for solar cell application and the characteristics of GaAsP/Si monolithic tandem solar cells are described. The conversion efficiency is improved by using thermal cycle annealing (TCA) and a graded buffer layer. TEM micrographs show that the dislocation density is drastically decreased with using TCA. The conversion efficiency of GaAsP solar cell on Si with GaAs buffer layer is higher than that with GaP buffer layer. The improvement in the efficiency is obtained by reducing the dislocation density in the GaAsP layer.

Experimental and Theoretical Investigations on Phase Diagrams of Fe Base Ternary Ordering Alloys

Abstract: Phase decompositions in several Fe-Al (or Si)-X (X=V, Co, Ge, Ni) ordering alloy systems were investigated mainly by means of transmission electron microscopy and the phase diagrams were thereby constructed. Many types of phase diagram were obtained. In Fe-Si-V system a wide composition range of the phase separation into disordered A2 and ordered D03 phases is observed at temperatures lower than Curie temperature, while at the higher temperatures the A2+D03 two-phase field becomes narrow. In Fe-Si-Co alloy, the phase separation into B2 and D03 occurs in two separate composition regions; one is the region connecting with the B2+D03 region in the Fe-Si binary system, and the other exists separately near the Fe-14.3 at%Si-28.3 at%Co alloy. In Fe-Al-V system the phase separation of A2+D03 occurs in a large region of Fe-rich corner. For Fe-Al-Ge and Fe-Si-Ge systems the experimental phase diagrams are also proposed. The free energies of A2 phase and B2 and D03 ordered phases in the ternary systems are evaluated by a statistical approach employing the Bragg-Williams-Gorsky approximation: the magnetic interactions are taken into account up to the second nearest neighbour spins of atoms as well as the usual atomic interactions up to the second nearest neighbours. The equilibrium phase diagrams and the Curie-temperature theoretically given by the present calcuation are almost consistent with the diagrams experimentally obtained. The influences of the magnetic energy on the structural stability of ordered phases are also demonstrated. The theoretical description proposed here is useful for the thermodynamic implication of the equilibrium phase diagram.

Partial Deduction of Disjunctive Logic Programs: A Declarative Approach

Abstract: This paper presents a partial deduction method for disjunctive logic programs. We first show that standard partial deduction in logic programming is not applicable as it is in the context of disjunctive logic programs. Then we introduce a new partial deduction technique for disjunctive logic programs, and show that it preserves the minimal model semantics of positive disjunctive programs, and the stable model semantics of normal disjunctive programs. Goal-oriented partial deduction is also presented for query optimization.

Recurrence conditions for multidimensional processes of Ornstein-Uhlenbeck type

Abstract: A stochastic process of Ornstein-Uhlenbeck type on the Euclidean space is a Markov process obtained from a spatially homogeneous Markov process undergoing a linear drift force determined by a matrix -Q. We give a criterion of recurrence and transience for a process of this type under the assumption that Q is diagonalizable and its eigenvalues are positive. No restriction is imposed on the part of the spatially homogeneous Markov process. Rigorous definition of our process is as follows. Let G be an operator defined by

Eigenfunction Expansion and Higher Order Weight Functions of Interface Cracks

Abstract: In this paper the properties of the eigenfunction expansion form in the interface crack problem of plane elasticity are discussed in detail. After using the Betti’s reciprocal theorem to the cracked dissimilar bonded body, several path-independent integrals are obtained. All the coefficients in the eigenfunction expansion form, including the K1 and K2 values, and the J-integral can be related to corresponding path independent integrals. Possibility for formulating the weight function is also suggested.

True Auger spectral shapes: A step to standard spectra

Abstract: We have developed a novel cylindrical mirror Auger electron analyzer with the well defined electric field of 0.1°% and the residual magnetic field of less than 1 mG. The CMA has a coaxial electron gun and the entrance angles are 42.3 o ±6 o . The theoretically calculated energy resolution of 0.24% was obtained and the transmission was estimated to be 5.6%. This CMA can be used to obtain an absolute Auger electron yield with errors in peak heights of 5%, with an uncertainty in the energy position of 0.1 eV (or 0.01%), and with ghost intensities due to scattering of 0.1-0.2%; for energies greater than 10 eV. Samples of polycrystalline gold, silver, and copper have been examined

A New Tightening Technique for Threaded Fasteners

Abstract: A new technique for tightening threaded fasteners was proposed aiming to assure the quality and the reliability in the tightening operations. The technique is based on the torque difference and the relative rotation angle in tightening and loosening process, and no preliminary experiment is required. Repeated tightening (and loosening) experiments were performed for different types of lubricant to verify the applicability of this technique. Experimental results show that the preload provided to the joint can be estimated with high accuracy and precision by this technique, and the possibility to boost the reliability of tightening control is confirmed.

Section 3. Sol-gel processing and chemical processing of glass

Abstract: Glasses containing up to 15 mol% Al2O3 or ZrO2 were prepared by the sol-gel process. Gels synthesized through the hydrolysis of alkoxide complexes were concluded to consist of Al&.sbnd;OSi or ZrOSi bonds from SAXS data. Gels shrunk by the dehydration-condensation of hydroxyl groups bonded to Al or Zr atoms in the temperature range of 300–800°C. The glasses were crystallized to precipitate mullite or tetragonal zirconia near the porous-nonporous conversion temperature. The Young's modulus increased with increasing content of Al2O3 or ZrO2 and reached 100 GPa at the composition of 15Al2O3·85SiO2.