Search

An overview of advances and progress on the KSTAR plasma control improvement is given. The enhancement of the KSTAR plasma control system (PCS) continues in order to enable implementations of more sophisticated control algorithms and capabilities of integrated controls on magnets, gas, heating and off-normal event handling. Features and functionalities on the generic magnetic controls, kinetic controls and new fault scheme design are added for the operation space expansion, mainly regarding recent achievements of high plasma current up to 1.1 MA for 10 s, high-performance long pulse up to 90 s, and discharges relevant to ITER research. Technical challenges and prospective upgrades in the near future are described.

Chitosan-based composite films with different amounts of grapefruit seed extract (GFSE) (0.5, 1.0 and 1.5% v/v) were fabricated via solution casting technique. Experimental results showed that GFSE was uniformly dispersed within all chitosan film matrices. The presence of GFSE made the films more amorphous and tensile strength decreased, while elongation at break values increased as GFSE content increased. Results from the measurement of light transmission revealed that increasing amounts of GFSE (from 0.5 to 1.5% v/v) did not affect transparency of the films. Furthermore, packaging of bread samples with chitosan-based GFSE composite films inhibited the proliferation of fungal growth as compared to control samples. Hence, chitosan-based GFSE composite films have the potential to be a useful material in the area of food technology.

Ring forging process is more appropriate for high-length and thin walled ring, because it utilizes the forging press and hence does not require heavy-duty ring rolling mill. Although ring forging process is very simple and economic for facilities, the process is not efficient because of multi-forging-step and low material utilization. An effective ring forging process is developed using a hollow ingot. When a hollow ingot is used with a workpiece, the ingot can be forged into a final ring without multi-stage pre-forging process, such as, cogging, upsetting, and piercing, etc.. Finally it has advantages of the material utilization and process improvement because a few reheating and forging process are not necessary to make workpiece for ring forging. The important design variables are the applied plastic deformation energy to eliminate cast structure and make uniform properties. In this study, the mechanical properties after forging of hollow cast ingot were investigated from the experiment using circumferential sectional model. Also, the effects of process variables were studied by FEM simulation on the basis of thermo-visco-plastic constitutive equation. Applied strain is different at each position in length direction because diameter of hollow ingot is different in length direction. The different strain distribution become into a narrow gap by additional plastic deformation during diameter extension process.

Transport and magnetization of MgIn 2− x Mn x O 4 polycrystalline pellets (0 x 2 O 4 with Mn results in an increase in electrical resistivity and a decrease in electron concentration. The electrical resistivity increases with decreasing temperature throughout the temperature range and variable-range hopping is observed at low temperatures. The diamagnetic pure MgIn 2 O 4 changes to paramagnetic after doping. The paramagnetism of the doped samples obeys the Curie–Weiss law. The magnetic-field dependence of the magnetization of the doped samples can be well described by the Brillouin function.

The Karhunen–Loeve Galerkin procedure is a type of Galerkin methods that employs the empirical eigenfunctions of the Karhunen–Loeve decomposition as basis functions. This technique can reduce nonlinear partial differential equations to sets of minimal number of ordinary differential equations by limiting the solution space to the smallest linear subspace that is sufficient to describe the observed phenomena. Previously [1] , it has been shown that one dimensional Burgers equation is reduced to a low dimensional model by this method, which is employed to solve boundary optimal control problems very efficiently. The present paper demonstrates that the Karhunen–Loeve Galerkin procedure can be extended to solve problems of the boundary optimal control of multidimensional Navier–Stokes equations. Since the reduction of modes in the multidimensional case is much larger than that in the one dimensional case, the present technique is found to be more powerful when applied to the control problems of the Navier–Stokes equation than those of the Burgers equation.

The Burgers equation is a simple one-dimensional model of the Navier-Stokes equation. In the present paper, we suggest an efficient method of solving optimal boundary control problems of the Burgers equation, which is practical as well as mathematically rigorous. Our eventual purpose is to extend this technique to the control problems of viscous fluid flows. The present method is based on the Karhunen-Loeve decomposition which is a technique of obtaining empirical eigenfunctions from the experimental or numerical data of a system. Employing these empirical eigenfunctions as basis functions of a Galerkin procedure, one can a priori limit the function space considered to the smallest linear subspace that is sufficient to describe the observed phenomena, and consequently reduce the Burgers equation to a set of ordinary differential equations with a minimum degree of freedom. The resulting low-dimensional model of Burgers equation is shown to simulate the original system almost exactly. The present algorithm is well suited for the problems of control or optimization, where one has to solve the governing equation repeatedly but one can also estimate the approximate solution space based on the range of control variables. The present method of solving boundary control problems of Burgers equation employing the lowdimensional model obtained by the Karhunen-Loeve Galerkin procedure is found to yield accurate results in a very efficient way, when the minimization of the objective function is performed using a conjugate gradient method.

Two plateaux are observed in the desorption isotherm for palladium hydride: a lower plateau pressure for a hydrogen/metal atom ratio (H/M) less than about 0.3 and a slightly higher plateau pressure for H/M greater than about 0.3. This higher pressure corresponds to the reported pressure for palladium hydride. These observations were made for a large surface area palladium powder exposed to both protium and tritium. Helium buildup from tritium decay decreases the lower plateau pressure but does not affect the observations for H/M greater than about 0.3. A multiple-energy hydrogen site occupancy model is proposed to explain qualitatively both the dual plateau and the helium effect in palladium hydride.

Ferroelectric properties of Lead-free (Bi,La)4Ti3O12 (BLT) films were evaluated on the newly developed MTP (Merged Top-electrode and Plate-line) cell structure. The BLT film was deposited by pulsed-DC sputtering method on a buried Pt/IrOx/Ir bottom electrode stack with W-plug. The BLT composition in the sintered sputtering target was Bi4.8La1.0Ti3.0O12. However, the deposited film composition was about Bi4.0La1.0Ti3.0O12 after the heat treatment of crystallization at 700°C/O2/30sec. And grains of the BLT film were randomly oriented and uniformly small ellipsoidal shape (long direction: ~100nm, short direction: ~20 nm). The remnant polarization (2Pr) and the leakage current density measured in the 100nm-thick BLT film were about 21 C/cm2 and 3 ×10-5 A/cm2 at 3 V, respectively. The fatigue loss was about 10% of the initial polarization value after 1×1011 fatigue cycles.