Effect of Moving Speed of Charged Metallic Spherical Electrode on Electrostatic Discharge

In this investigation, the nature of the electrostatic discharge (ESD) that occurs when a charged object moves toward a stationary grounded object is experimentally clarified. The spark lengths, discharge currents, and induced voltages in a magnetic probe were measured when a charged metallic spherical electrode connected to a 422 pF capacitor approached a stationary grounded object, which was the current target, for different moving speeds of the charged metallic spherical electrode in a range of 1 mm/s to 100 mm/s. The charge voltages of the capacitor were +6.5 kV and +10 kV. Based on the results, the average gap length shortened with the speed of the spherical electrode. The average peak values of the discharge current and the induced voltage were likely to increase with the speed of the spherical electrode. The average rise times of the discharge current and the induced voltage were likely to drop with the speed of the spherical electrode. The relation between the spark length and the discharge current due to the ESD can be explained qualitatively by using an equation derived from the spark resistance formula proposed by Rompe and Weizel.     

Breakdown characteristics of oil and paper insulation for a very fast transient voltage

This paper describes the dielectric breakdown characteristics of oil and oil‐impregnated paper for very fast transient (VFT) voltages. Blumlein circuits generate VFT voltages of 60 and 300 ns in a pulse width that simulates disconnecting switching surges in gas‐insulated switch gears. We measured the breakdown voltages of needle‐to‐plane, plane‐to‐plane oil gaps and several pieces of paper between plane electrodes for VFT and lightning impulse voltages. The measured data were formulated in V‐t characteristics and Weibull probability distributions. The inclination n of V‐t characteristics of insulating paper is 150, which is less than n = 13.7 of the plane‐to‐plane oil gap in the VFT time range. The shape parameters of Weibull distribution obtained in this study show that the scattering of breakdown voltages of paper is much less than that of oil. © 2002 Wiley Periodicals, Inc. Electr Eng Jpn, 141(4): 16–24, 2002; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10043     

Non-axisymmetric buckling behaviour of elastic-plastic circular tubes subjected to a nosing operation

Theoretical investigations have been carried out to predict the non-axisymmetric buckling seen in the throat of circular elastic-plastic tubes subjected to a nosing operation along a frictionless conically shaped die. The buckling points and associated modes are determined by Hill's bifurcation theory in conjunction with a non-axisymmetric buckling mode. The results show that increasing the die semi-angle and the tube thickness or decreasing the material work-hardening rate are always beneficial to improve the buckling limit. The associated critical buckling mode number generally decreases as the tube thickness increases and does not depend drastically on the die semiangle nor on the hardening rate. The effect of the average r value is substantial and the buckling limit is improved when the r value reduces. Part of the present results predict well the results observed in existing experimental work.     

Characteristics of thermally expanded core fiber

Thermally expanded core (TEC) fiber is expected to reduce fiber-to-fiber and fiber-to-laser diode connection loss. This paper describes the characteristics of TEC fiber theoretically and experimentally. We reveal theoretically that when fabricating TEC fiber the mode field diameter (MFD) is enlarged more effectively by increasing the heating temperature rather than the heating time. In the 1300-1600°C temperature range with heating times between 0 and 60 min, it is necessary to control the temperature accurately so that no deviation from the target temperature is more than ±30°C. This is in order to ensure that any connection loss caused by MFD mismatch is less than 0.1 dB. We show experimentally that the propagation loss of TEC fiber is dependent on the heating region and wavelength by using a micro burner with a propane/oxygen flame. Based on the relationship between the loss characteristics and the expanded MFD, we suggest a method for nondestructively measuring the MFD in TEC fibers     

Abnormal development and differentiation of macrophages and dendritic cells in viable motheaten mutant mice deficient in haematopoietic cell phosphatase

In mice homozygous for the 'viable motheaten' (mev) mutation, numbers of macrophage progenitor cells, particularly monocytes, were markedly increased in the bone marrow and spleen. Increased mobilization of these precursor cells to peripheral tissues and their differentiation to macrophages were evidenced by striking increases in macrophage numbers. Immunohistochemical double staining of tissue sections and flow cytometry analyses of single cell suspensions from these mice demonstrated CD5 (Ly-1)-positive macrophages in the peritoneal cavity, spleen and other tissues. Ly-1-positive macrophage precursor cells were demonstrated in the peritoneal cavity of the mev mice and developed in the omental milky spots. The development of marginal metallophilic and marginal zone macrophages was poor in the splenic white pulp and related macrophage populations were absent in the other lymphoid tissues. The numbers of epidermal Langerhans cells in the skin and T cell-associated dendritic cells in the thymic medulla, lymph nodes, and the other peripheral lymphoid tissues were decreased. However, increased numbers of dendritic cells accumulated in the lungs, liver, and kidneys. These abnormalities in development and differentiation of macrophages and dendritic cells may be ascribed to the deficiency in haematopoietic cell SHP-1 tyrosine phosphatase or may be a secondary consequence of abnormal microenvironments, (either constitutive or in response to inflammatory stimuli) in the haematopoietic and lymphopoietic organs and tissues of these mice.     

Epidermodysplasia verruciformis accompanied by familial large granular lymphocytosis and a decrease in T lymphocytes

A 40-year-old man with epidermodysplasia verruciformis showed a decrease in peripheral blood T cells and abnormal expansion of large granular lymphocytes, accompanied by increased natural killer cell activity. Surface marker analysis of his large granular lymphocytes demonstrated that the subset, CD 57+ and CD 16+, had increased. His father, who had no skin lesions of epidermodysplasia verruciformis, displayed similar blood changes and his brother showed a decrease in T cells and a slight increase in CD 16+ natural killer cells, whereas his mother revealed only a slight decrease in T cells. Our present study indicates that epidermodysplasia verruciformis might be associated with hereditary abnormal expansion of large granular lymphocytes and a decrease in T cells.     

A Fuzzy Expert System for Damage Assessment Using Genetic Algorithms and Neural Networks

Abstract: An efficient knowledge-acquisition support method is required for improvement and maintenance of the knowledge base in durability evaluation of an RC bridge deck. Such a method is proposed in this paper to automatically acquire fuzzy production rules. This method makes joint use of genetic algorithms and a neural network. Using a neural network as a subsystem, the evaluation function of genetic algorithms can be provided with the weights of the neural network. Introducing a neural network into genetic algorithms, it is possible to acquire new knowledge so that the method is useful when it is difficult to acquire knowledge in the field.     

Accumulation of amplified target DNAs using thiol/biotin labeling, S1 nuclease, and ferrocene-streptavidin-magnetic system and a direct detection of specific DNA signals with screen printed gold electrode

Combinations of PCR-based amplification platform using 5′ thiolated and biotinylated specific primers, S1 nuclease-PCR products treatment, ferrocene-streptavidin (Fc-Stv)-magnetic binding for DNA accumulation, and screen printed gold electrode for the DNA allocation, were applied to Hoechst 33258-induced DNA aggregation and signals induction system for direct signals detection and DNA quantification in food samples. Thiolated and biotinylated at each 5′ terminus enabled DNA purification through S1 nuclease treatment for primers and non-specific DNA elimination and enabled DNA trapping with a ferrocene-streptavidin-magnetic system. This facilitated the accumulation of target DNAs at higher concentration, resulting in enhanced signals. After allocation of DNA on the surface of gold electrode via thiol binding, intensity of DNA signals through these treatments could be measured directly after being induced by Hoechst 33258. Wider amplitude changes in anodic current peaks between negative and positive samples (increasing from 3.70 to 10.10 μA) compared with those applied with no treatment combinations (decreasing from 3.92 to 1.23 μA) were observed. This enhancement of the signals allowed a greater efficiency of DNA quantification. When this combination was used for GMOs content estimation in reference samples, results revealed an improved accuracy from 66% to 96%. The combined biosensor system, although more costly than the standard Hoechst 33258/carbon electrode system, provided an alternative choice for DNA quantification, offering labor-free immobilization of probe onto electrode surface, easy test administration, and efficient semi-quantitative test without expensive instruments.     

Yttria Doping and Sintering of Submicrometer-Grained α-Alumina

The sintering behavior of α-alumina powders doped with magnesia (500 or 1500 ppm) and yttria (0, 500, or 1500 ppm) was investigated using constant-heating-rate dilato-metric experiments. The apparent activation energies for the intermediate stage of sintering were 740, 800, and 870 kJ/mol for 0, 500, and 1500 ppm yttria doping levels, respectively; these were independent of magnesia doping. Yttria-doped powder compacts exhibited systematic anomalous second peaks in the densification rate curves at certain grain sizes which were determined only by yttria doping levels. Before the anomalous peak, with lower yttrium contents at grain boundaries, yttrium in an atomic state delays densification and raises the apparent activation energy. Beyond the peak, with higher yttrium contents at grain boundaries, yttria-rich precipitation delays the densification. Within the peak, yttrium segregation near the saturation level enhances densification.