11,147 research outputs found
Ni/MH 셀의 잔존 용량 측정 방법
No full textThe present invention relates to a method of measuring residual capacity of a Ni/MH (nickel/metal hydride) cell by measuring the change in the electrical resistivity of a Ni/MH cell according to the change of the concentration of hydrogen in metal hydride. According to the present invention, a method for measuring residual capacity of a Ni/MH cell comprises the steps of measuring electrical resistivity of a first Ni/MH cell, and determining the residual capacity of the first Ni/MH cell (i) from a predetermined data of n-pairs of electrical resistivity values and residual capacity values of a second Ni/MH cell which has substantially the same composition as the composition of the first Ni/MH cell, or (ii) based on a predetermined functional relationship between the electrical resistivity and residual capacity of the second Ni/MH cell. The series of the predetermined data or the predetermined functional relationship represents substantially a linear proportionally between the resistivity and the logarithmic value of the residual capacity. As the discharge reaction proceeds in the cell, metal hydride in the anode is reduced and loses hydrogen, and thus the hydrogen concentration at anode becomes lower. Accordingly, the relationship between the residual capacity and the resistivity of a Ni/MH cell can be obtained by measuring the residual capacity and the resistivity of the cell depending on the degree of discharge, therefore the residual capacity can be readily detected by measuring only the resistivity of the cell
Interrelationship of apoptosis, mutation, and cell proliferation in N-methyl-N '-nitro-N-nitrosoguanidine (MNNG)-induced medaka carcinogenesis model
No full textThe present study examined the interrelationship of GSH depletion, apoptosis, mutation. and cell proliferation following carcinogen exposure. Medaka (Oryzias latipes) were investigated following a 28 day, three times/week pulse exposure to N-methyl-N'-nitro-N'-nitrosoguanidine (MNNG). Fish (5 weeks old) were exposed to MNNG at concentrations of 0, 0.5, and 1 mg l(-1) and reared for 3, 5 and 7 more months after the last day of exposure. GSH levels were decreased in the higher concentration groups and longer-reared groups. Flow cytometric analysis revealed that fish from the groups reared 3 and 5 months showed active apoptotic changes in the dose- and time-dependent manner, but the group reared 7 months had fewer apoptotic, rather showed more necrotic and carcinogenic alterations. Mutational responses were detected by an arbitrarily primed polymerase chain reaction (AP-PCR) fingerprinting method using whole body DNA samples as templates and pBR primer. A mutational change was expressed by a loss or gain of a band. There was a time-dependent mutational change. but no distinctive concentration-dependent one. A band from normal fish sample that disappeared after treatment of MNNG was excised and sequenced. The band had an 869 base pair-long sequence, however, there was no putative protein-coding region based on an analysis by DNAsis. Spindle cell sarcomas invading muscle were detected on the whole body sections from three of ten fish examined, and immunohistochemical analysis with PCNA showed that tumor cells were actively proliferating. However, terminal deoxynucleotidyl transferase (TdT) assay showed that tumored fish still had active apoptotic cell changes in the tissues without tumor. This study shows not only the interrelationship of GSH depletion, apoptosis, mutation and cell proliferation, but also indicates that medaka is appropriate as a fish model for research on the passage of carcinogenesis, (C) 2000 Elsevier Science B.V. All rights reserved.N
Robust economic optimization of process design under uncertainty
No full textIn this study, ranges of model parameters are analyzed for robustness measures. In particular, the properties of partial mean and worst-case cost in robust optimization are investigated. The robust optimization models are considered as multiobjective problems having two objectives, the expected performance (i.e. expected cost) and a robustness measure (Suh, M. and Lee, T. ( 2001) Robust optimization method for the economic term in chemical process design and planning. Industrial & Engineering Chemical Research, 40, 5950 - 5959). The robust partial mean model is defined with objectives of expected value and partial mean. The robust worst-case model is defined with the objective of expected value and worst-case. They are proved to guarantee Pareto optimality, which should be satisfied for multiobjective optimization problems. A graphical representation of the meaningful parameter ranges is clearly defined with mathematical proofs. The robustness of the solutions is discussed, based on the analysis of the ranges of the parameters. Three meaningful ranges of the parameters are investigated to choose a proper target value for the robust partial mean model. The worst-case value obtained from the worst-case analysis is recommended as the most effective target value, in order to obtain the optimal solution in a tradeoff between robustness and optimality. The proposed analysis in this study is validated with examples in chemical process design problems
AEROELASTIC ANALYSIS OF MULTIBLADED HINGELESS ROTORS IN HOVER
No full textThe coupled flap-lag-torsion aeroelastic response and stability of multibladed hingeless rotors in the hovering flight condition are investigated. The vortex lattice method, with a three-dimensional prescribed wake geometry, is used for the prediction of unsteady airloads of multibladed rotors undergoing disturbed dynamic motions. Interblade unsteady wake effects due to vortex-phasing phenomena beneath a rotor are numerically calculated by the phase control of wake vortices shed from each blade. The aeroelastic equations of motion of the rotor blade are formulated using a finite element beam model that has no artificial restrictions on the magnitudes of displacements and rotations due to the degree of nonlinearity. Numerical results of the steady equilibrium deflections and the lead-lag damping and frequency are presented for two-, three-, and four-bladed stiff-inplane rotors, and are compared with those obtained from a two-dimensional quasisteady strip theory with steady and uniform inflow
Phase equilibria of carbon dioxide hydrate system in the presence of sucrose, glucose and fructose
No full textThe three-phase (H-L-w-V) equilibria of the carbon dioxide hydrate formation system in aqueous solutions containing sucrose, glucose, and fructose were experimentally determined at pressures ranging from 1.580 to 4.355 MPa and at temperatures between 273.6 and 281.7 K, The upper quadruple points (H-L-w-L-CO2-V) were also measured at concentrations of 10, 20, and 30 mass % sucrose, glucose, and fructose. The addition of carbohydrates exhibited a similar inhibition effect as that observed for electrolytes and alcohols. A thermodynamic model predicting the three- and four-phase hydrate equilibria while accounting for the inhibition effect of carbohydrates was developed on the basis of the van der Waals-Platteeuw model and the Redlich-Kwong-Soave equation of state with a modified version of the Huron-Vidal mixing rule. The calculated results were found to be in good agreement with the experimental data.This
work was supported by grant No. 98-0502-04-01-3 from the Basic
Research Program of the KOSEF
SUPERSONIC FLUTTER ANALYSIS OF CLAMPED SYMMETRICAL COMPOSITE PANELS USING SHEAR DEFORMABLE FINITE-ELEMENTS
No full textTHE flutter analysis of composite panels in supersonic flow has been performed by the finite element method based on the first-order shear deformable theory. The computational results of the vibration and flutter analysis agree well with the results given in the available references. Flutter boundaries have been obtained for both cross-ply and angle-ply composite plates. Also, the flutter analysis has been performed for both rectangular and trapezoidal plates with clamped edges. The plate aspect ratio, flow direction, and fiber orientation affect greatly the flutter boundaries
AEROELASTIC STABILITY OF HINGELESS ROTOR BLADE IN HOVER USING LARGE DEFLECTION THEORY
No full textThe coupled flap-lag-torsion aeroelastic stability of a hingeless rotor blade in hover is investigated using finite elements based on large deflection beam theory. The finite element equations of motion for beams arbitrary large displacements and rotations, but small strains, are obtained from Hamilton's principle. The stability boundary is calculated assuming blade motions to be small perturbations about the nonlinear steady equilibrium deflections, which are obtained through an iterative Newton-Raphson method. The p-k modal flutter analysis based on coupled rotating natural modes is used. Various unsteady two-dimensional strip theories am used to evaluate the aerodynamic loads. The sensitivity of the stability boundary to these aerodynamic assumptions is examined. Numerical results of the steady deflections and stability boundaries are presented for some representative blade configurations and also compared with those given in previous moderate deflection type theories
FINITE-ELEMENT ANALYSIS OF COMPOSITE PANEL FLUTTER
No full textThe finite element method based on the shear deformable theory is developed to analyze the composite panel flutter in supersonic flow. The computational results of the vibration and flutter analysis agree well with those given in the available references. Guyan reduction and the normal mode method are used to reduce the computational time. The plate length ratio, the flow direction and the fiber orientation greatly affect the flutter boundaries of trapezoidal laminated plates. Flutter boundaries have been calculated for both simply supported and clamped boundaries in order to determine the effect of boundary conditions
Magnetic uniaxial alignment of the columnar superstructure of discotic metallomesogens over the centimetre length scale
No full textThe uniaxial alignments of the columnar superstructure of discotic metallomesogens, cobalt octa( n-dodecylthio) porphyrazine (CoS12), over the centimetre length scale have been achieved by spinning samples under a static magnetic field. The orientations of the columnar superstructures were investigated by small angle neutron scattering ( SANS) and cryogenic transmission electron microscopy (cryo-TEM). Upon cooling from the isotropic phase to the columnar mesophase in the presence of a static magnetic field (0.4 - 1.1 T), CoS12 formed oriented columnar superstructures with the columnar directors being isotropically distributed in the plane normal to the external magnetic field. When the samples were continuously spun during cooling in a static applied magnetic field of 1.0 T, CoS12 was observed to form uniaxially aligned columnar superstructures with the columnar domain directors being parallel to the rotation axis which was normal to the external field. The optimal rotation speed for the alignment was found to be as low as 5 - 10 rpm, where the full width at half maximum of the domain director distribution is minimized. The uniaxial alignments were achieved over a macroscopic length scale (ca. 1 cm). Cryo-TEM measurements revealed that the persistence length of the uniaxially aligned columns was at least 1 mu m.This work was supported by the program of the Basic Atomic
Energy Research Institute (BAERI) which is a part of the
Nuclear R&D Programs funded by the Ministry of Science &
Technology (MOST) of Korea and the HANARO Utilization
Program (M2-0363-00-0063). We thank the HANARO at
KAERI and NCNR at NIST for SANS beamtime supports.
The work utilized NIST facilities supported in part by the
National Science Foundation under DMR-9986442. We also
thank J.-K. Kim, S.-M. Kim and J.-Y. Lee at Korea Basic
Science Institute (KBSI) for technical assistance during
cryo-TEM measurements and J.-S. Lee for DSC and POM
measurements
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