Integrated Filters and Their Combined Effects in Matrix Converter

A matrix converter has a topology that inherently exhibits sinusoidal input current waveforms and has small output voltage steps. This paper proposes to integrate the matrix converter with filters, which provide lower electromagnetic interference (EMI), lower common-mode current, lower shaft voltage, and sinusoidal output voltage waveforms. A salient aspect of the proposed integration is its ability to significantly reduce the value of the input EMI filter capacitors and still meet strict EMI regulations. This helps in reducing the ground leakage current, which in the past has been a serious limitation in applying EMI filters with low ground currents for human and cattle safety     

Myogenic induction of human mesenchymal stem cells by culture on dendrimer-immobilized surface with d-glucose display

Culture surfaces were designed by immobilizing dendrimer with d-glucose display, that is, 1st-generation (G1) and 3rd-generation (G3) dendrimer surfaces. In the cultures of human mesenchymal stem cells (hMSCs), the effect of the prepared culture surfaces was examined in terms of regulating cell morphology and differentiation. The time-lapse observation revealed that the cells on the G3 surface showed more dynamic behaviors of temporal stretching and contracting associated with stimulated migration, as compared with the cells on the G1 and plain surfaces. On the G3 surface, moreover, a frequency of round-shaped cells increased, and spreading of the cells was appreciably suppressed. From the cytoskeletal staining of F-actin, it was found that the immature stress fibers were of significance in the cells on the G3 surface. In addition, the cells on the G3 surface expressed RhoA inactivation and Rac1 activation during the culture, indicating that the G3 surface permits the regulation of RhoA and Rac1 expression associated with altering in cellular morphology and migratory behaviors. It was also found that desmin expression was, in particular, promoted on the G3 surface, thus supporting the consideration that a balance of Rho family GTPases activation induces myogenesis in hMSCs. The current results suggest that the dendrimer surface can be a potential tool for the guided differentiation of hMSCs directing to myocyte-like cells in the absence of an aqueous myogenesis-inducing factor.     

Fabrication of UV range light guide plate

The light guide plate, as part of the backlight unit in a cellular phone or liquid crystal display, has evolved to meet market demands for low power consumption, high-luminance and high-quality displays. Along with the advance of the light guide plate, LEDs have undergone development as light source for light guide plates. Surpassing the limitations of LED emission in the visible light range, LEDs that emit UV light have been developed. In recent years, the UV light are used as a source of light of the air cleaner, and it is used as a source of light to activate the titanium oxide which is photocatalyst. But common UV light sources are either line or point light sources. We study surface illuminators that incorporate diffusers in the visible light range. Applying our existing technology, we constructed an unprecedented UV surface illuminator (surface light source) and measured it using a photocatalyst. The experiment results are presented in this report.     

TEM/STEM Observation of ZrC-Coating Layer for Advanced High-Temperature Gas-Cooled Reactor Fuel

The Japan Atomic Energy Agency (JAEA) has started to study and develop ZrC-coated fuel particles for advanced high-temperature gas-cooled reactors. The ZrC-coating layer was fabricated using the bromide process at JAEA. In the early stage of the project, however, the deposition temperature was varied. This paper mainly focuses on the microstructures of the ZrC-coating layer developed in the early stage of the project. Some circumferential stripes were observed in the ZrC-coating layer on optical micrographs. It was found that the stripes were caused by the nonuniform distribution of the free carbon phase. It was also revealed by means of transmission electron microscope /scanning transmission electron microscope observations that crystal grains of the ZrC were small and columner in shape, and were not equiaxed especially near the surface. It appears that the oscillated deposition temperature results in the nonuniform distribution of the free carbon region. The structure of the free carbon region formed in the ZrC-coating layer appeared to be such that the c -plane was roughly parallel to its lengthened direction. The ZrC-coating layer appeared to be bound to the PyC layer. Fibrous carbon existing at the PyC/ZrC boundary was also observed.     

Residual DC charge leakage mechanism of a transmission line under fine and dry weather conditions

The decay time of residual DC charge in 500‐kV transmission line was measured during five fine and dry days of winter. The results showed a large scattering not dependent on the simultaneously observed weather conditions, such as temperature or relative humidity. The authors performed an additional experiment in a laboratory to discuss the factors that affect the residual DC charge leakage in dry conditions focusing on the moisture in the air and the dust floating in the atmosphere. It is shown that absolute humidity alone decides the decay time without scattering under clean and calm condition. The floating dust blown up by the wind, however, reduces the decay time and brings a large scattering. The dust should be a charge carrier moving freely in the atmosphere. © 2008 Wiley Periodicals, Inc. Electr Eng Jpn, 165(2): 45–52, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20417     

A proposal of a WDM transmission system using three wavelength bands of 1.3, 1.47, and 1.55 μm employing optical amplifers

A WDM transmission system using the wavelength bands of 1.3, 1.47, and 1.55 μm is proposed. Selection of these wavelengths makes it possible to use off‐the‐shelf optical couplers and to apply known types of amplifiers. Among three kinds of optical amplifiers, Tm³⁺‐doped fiber amplifiers for the 1.47 μm band are constructed and their basic properties are determined experimentally. Crosstalk between the 1.47‐ and 1.55‐μm bands originating from insufficient isolation of the couplers and Raman scattering becomes negligibly small by considering the combination of the couplers and reducing the input optical power to the single mode fiber (SMF) to below 6 dBm. Experiments on repeaterless transmission over a 50‐km SMF show error‐free performance in the 10 Gb/s × 6 WDM case where two light signals of different wavelength are launched in each band. Finally, the utility of the 1.47‐μm band is discussed theoretically. © 2001 Scripta Technica, Electr Eng Jpn, 135(2): 43–51, 2001     

Transient photoinduced 'hidden' phase in a manganite

Photoinduced phase transitions are of special interest in condensed matter physics because they can be used to change complex macroscopic material properties on the ultrafast timescale. Cooperative interactions between microscopic degrees of freedom greatly enhance the number and nature of accessible states, making it possible to switch electronic, magnetic or structural properties in new ways. Photons with high energies, of the order of electron volts, in particular are able to access electronic states that may differ greatly from states produced with stimuli close to equilibrium. In this study we report the photoinduced change in the lattice structure of a charge and orbitally ordered Nd(0.5)Sr(0.5)MnO(3) thin film using picosecond time-resolved X-ray diffraction. The photoinduced state is structurally ordered, homogeneous, metastable and has crystallographic parameters different from any thermodynamically accessible state. A femtosecond time-resolved spectroscopic study shows the formation of an electronic gap in this state. In addition, the threshold-like behaviour and high efficiency in photo-generation yield of this gapped state highlight the important role of cooperative interactions in the formation process. These combined observations point towards a 'hidden insulating phase' distinct from that found in the hitherto known phase diagram.     

A Two-dimensional Stress Analysis of Butt Adhesive Joints Having a Circular Hole Defect in the Adhesive Subjected to External Bending Moments

This paper deals with a two-dimensional stress analysis of butt adhesive joints, with a circular hole defect in the adhesive, subjected to external bending moments. The analysis was done using the two-dimensional theory of elasticity in order to examine the strength of the joints. It was assumed that the adherends were rigid and the adhesive was replaced with a finite strip including a hole defect. The effects of the location and size of a hole defect on the stress distributions around the hole and at the interfaces were obtained by numerical calculations. In addition, the singular stress near the edge of the interface was obtained. For verification, photoelastic experiments were performed. The analytical results were fairly consistent with the experimental results. It was seen that the principal stress around a hole becomes larger with a certain shift toward the free boundary. It was also seen that the stress concentration became larger with an increase of the size of the hole.     

Fetal plasma hypoxanthine level in growth-retarded fetuses before labor

Hypoxanthine is one of the purine nucleotides and is presumed to accumulate during hypoxia and acidemia. It remains uncertain, however, whether plasma hypoxanthine concentration is a useful indicator of fetal asphyxia; and its relationship to other markers of fetal physiologic state is not clearly defined. The aim of this study was to evaluate whether the level of fetal plasma hypoxanthine is correlated with fetal hypoxia and acidosis in growth-retarded fetuses before the onset of labor. Cordocentesis was performed in 34 growth-retarded fetuses at 31-35 weeks' gestation for the measurement of umbilical venous plasma concentrations of hypoxanthine, hemoglobin and lactate concentrations, blood gases, and base deficit. Umbilical venous plasma hypoxanthine concentration was found to be increased significantly, in parallel with the degree of acidosis (r = -0.74, P < 0.05) and base deficit (r = -0.41, P < 0.05), but not to bear a significant relationship to the degree of hypoxemia or other measured variables. We conclude that increases in the plasma concentration of hypoxanthine may reflect an impaired physiological state in growth-retarded fetuses before labor.