Dynamic preventive control for power system using transient stability assessment based on pattern recognition

To maintain power system security, the authors are developing an integrated security monitoring and control (ISMAC) system which consists of the three main functions: security monitoring, preventive control and emergency control. This paper focuses on the dynamic preventive control which deals with the transient stability immediately after the contingency has occurred. The proposed method is based on the transient stability assessment using the pattern recognition with two-dimensional feature space. Therefore, a preventive control strategy can be obtained rapidly. An index which represents the severity of the contingency quantitatively (security index) is defined by the distance from a linear decision surface which divides a feature plane into a stable and an unstable region. Further, this method has also the advantage that it is possible to consider the effect of the control devices or damping to some extent and specify the operator demand for stabilization flexibly. The effectiveness of the proposed method is ascertained through numerical examples for model power systems.     

In vivo acceleration of ultrasonic tissue heating by microbubble agent

The ultrasonic power absorbed by a microbubble in its continuous wave response is estimated through numerically solving a version of the Rayleigh-Plesset equation. At an ultrasonic frequency of 3 MHz, a resonant microbubble, approximately 1.1 microm in radius, showed an absorption cross section of about 0.005 mm2 in its low power response. This estimation predicts that the tissue ultrasonic absorption will be doubled when such microbubbles are delivered to the tissue at a concentration of about eight bubbles/mm3 in tissue. An exteriorized murine kidney was exposed to focused ultrasound at 3.2 MHz in degassed saline, and the tissue temperature change was measured. With an intravenous bolus administration of a microbubble agent, the ultrasonically induced temperature elevation was multiplied by up to five times. The enhancement in temperature elevation gradually decreased as the microbubble agent was eliminated from the body. The experimental results agreed with the prediction in the order of magnitude. This effect may have a potential use to enhance the throughput as well as the selectivity of focused ultrasound treatment.     

Development of a differential-absorption lidar system for measurement of atmospheric atomic mercury by use of the third harmonic of an LDS-dye laser

A differential-absorption lidar system that uses a long-life transmitter for monitoring of atomic-mercury concentrations in the atmosphere has been developed. The third harmonic of a tunable dye laser with LDS 765 dye pumped by the second harmonic of a Nd:YAG laser was used as the emitted beam from the transmitter. By use of this system, atmospheric concentrations of atomic mercury of less than 0.4 part in 10(12) were measured. The time trend of the measured concentration agreed with that obtained by a conventional gold amalgamation method combined with atomic absorption spectroscopy on the ground.     

Characterization of lytic enzyme activities of Lactobacillus gasseri with special reference to autolysis

Lactobacillus gasseri JCM 1130 and JCM 1131(T) exhibited autolytic activity in agar containing autoclaved cells of each strain as substrate. By zymogram analysis of JCM 1131(T), two lytic bands with apparent molecular masses of 54.5 and 35 kDa, were detected. Similarly, JCM 1130 yielded two lytic bands with apparent molecular masses of 35 and 33.5 kDa. In simple buffers as well, JCM 1131(T) suffered a drastic decrease in cell turbidity, but JCM 1130 did not undergo the decrease. The optimal pH for autolysis of JCM 1131(T) was in the range of 6.0-7.0, and the lysis was completely inhibited at pH 4-5. The lysis of JCM 1131(T) was suppressed by NaCl, in a concentration-dependent way. When subjected to UV irradiation or mitomycin C (MMC) treatment, cultures of both strains elicited conspicuous turbidity decrease after 2-4 h of growth, suggesting the occurrence of prophage induction. The 35-kDa lytic band of JCM 1131(T) and the 33.5-kDa protein of JCM 1130 were considerably increased by UV irradiation.     

Caffeine promotes premature chromosome condensation formation and in vitro development in porcine reconstructed embryos via a high level of maturation promoting factor activity during nuclear transfer

When the nucleus in G0/G1 phase is transferred to an enucleated oocyte by nuclear transfer (NT), its nuclear envelope is broken, followed by condensation of chromosome structure by maturation promoting factor (MPF). This morphological remodeling of the transferred interphase nucleus seems to be essential for subsequent development of NT embryos. In this study, we treated porcine NT embryos with caffeine, which has been reported to increase MPF activity, to keep their MPF level high during NT. When 2.5 mM caffeine was added to the handling medium, the proportion of NT embryos showing condensed chromosome increased significantly (P < 0.05). In NT embryos treated with caffeine, the activity of p34(cdc2) kinase was significantly (P < 0.05) higher than in those without caffeine at 3 h post-injection. In addition, the rate of development to the blastocyst stage after activation was significantly (P < 0.05) higher in NT embryos treated with caffeine. These results indicate that caffeine treatment can increase not only the rate of chromosome condensation but also the developmental rate to the blastocyst stage of porcine NT embryos. This action is most likely due to the support/increase of MPF activity throughout the process of NT.     

On-line preventive control for power system transient stability based on the energy function method

For the purpose of maintaining the power system security, an integrated security monitoring and control (ISMAC) system, is being developed in which both preventive and emergency control have important roles. Static security control strategies which deal with the steady state after the contingency is cleared, have been studied by various researchers including the authors. However, the basic research on dynamic security control which deals with the transient state immediately after the contingency has occurred is seldom found. This paper presents a method of dynamic preventive control for the transient stability considering plural contingencies and coordinating in a flexible way the requirements of both security and economy. In the preventive control for transient stability, it is necessary to judge the transient behaviors properly and also to evaluate the security quantitatively for a postulated contingency. The authors define a security index which represents absorbing capacity of post-fault kinetic energy based on the energy function method. The index has these advantages: it is possible to calculate values rapidly; and physical meanings are easily understood. The effectiveness of the proposed method is ascertained through numerical examples for model power systems.     

Three-Dimensional Simulation of the Ventricular Depolarization and Repolarization Processes and Body Surface Potentials: Nornal Heart and Bundle Branch Block

A three-dimensional computer model has been constructed to simulate the ventricular depolarization and repolarization processes in a human heart. The electrocardiogram (ECG), the vectorcardiogram(VCG), and the body surface potential map (BSPM) during the QRS-T period are obtained automatically under certain heart conditions such as bundle branch block and myocardial infarctions. The ventricles, together with bundle branches and the Purkinje fibers, are composed of approximately 50 000 cell units which are arranged in a cubic close-packed structure. A different action potential waveform was assigned to each unit. The heart model is mounted in a homogeneous human torso model. Electric dipoles, which are proportional to the spatial gradient of the action potential, are generated in all the cell units. These dipoles give rise to a potential distribution on the torso surface, which is calculated by means of the boundary element method. The resulting ECG's, VCG's, and BSPM's are within the expected range of clinical observations.     

The Constraints on Images of Rectangular Polyhedra

This paper discusses how polyhedron interpretation techniques are simplified if the objects are rectangular trihedral polyhedra. This restriction enables one to compute the spatial orientation of a given corner and its motion from its image in terms of polar coordinates, Eulerian angles, and quaternions. One can also interpret the shape and the face adjacency from local information only. The necessary constraints are listed, and some examples are given to compare the presented scheme to existing ones. The possible nonuniqueness of the interpretation is also discussed.