Plan for first phase of safety demonstration tests of the High Temperature Engineering Test Reactor (HTTR)

Safety demonstration tests using the High Temperature Engineering Test Reactor (HTTR) will be conducted for the purpose of demonstrating inherent safety features of High Temperature Gas-cooled Reactors (HTGRs) as well as providing the core and plant transient data for validation of HTGR safety analysis codes. The first phase safety demonstration test items include the reactivity insertion test and the coolant flow reduction test. In the reactivity insertion test, which is the control rod withdrawal test, one pair out of 16 pairs of control rods is withdrawn, simulating a reactivity insertion event. The coolant flow reduction test consists of the partial loss of coolant flow test and the gas circulators trip test. In the partial loss of coolant flow test, primary coolant flow rate is slightly reduced by control system. In the gas circulators trip test one and two out of three gas circulators are run down, simulating coolant flow reduction events. The gas circulators trip tests, in which position of control rods are kept unchanged, are simulation tests of anticipated transients without scram (ATWS).     

Orthogonal queries in segments

We consider theorthgonal clipping problem in a set of segments: Given a set ofn segments ind-dimensional space, we preprocess them into a data structure such that given an orthogonal query window, the segments intersecting it can be counted/reported efficiently. We show that the efficiency of the data structure significantly depends on a geometric discrete parameterK named theProjected-image complexity, which becomes Θ(n ²) in the worst case but practically much smaller. If we useO(m) space, whereK log^4d−7 n≥m≥n log^4d−7 n, the query time isO((K/m)^1/2 log^{max{4, 4d−5}} n). This is near to an Ω((K/m)^1/2) lower bound.     

An electrostatic microactuator using LIGA process for a magnetic head tracking system of hard disk drives

 We demonstrate an electrostatic micro actuator which is fabricated by LIGA process. The actuator is designed for a magnetic head tracking system of hard disk drives (HDDs). The actuator is essential to achieve very high track density of HDDs. We realize the aspect ratio of 125 by the LIGA process using a Si-Au mask. We propose to use PMMA molds both as the mechanical structure and as the insulator between electrodes. We believe there are great opportunity for the LIGA process in making micro actuators of HDDs. Received: 25 August 1997 / Accepted: 24 October 1997     

Legacy system program transformation by Lyee methodology

Based on the comparative review of several approaches to legacy system conversion and revitalization, the Lyee methodology application for the issue is presented to clarify its idea, the associated procedure, and the implemented tools. It could be said that with the tools and manual developed by ICBSM&T, the mechanical transformation of the conventional program to a Lyee-structured one becomes possible as long as the programs are made in a procedure-oriented language. In addition to the program structure conversion, the Lyee methodology permits people to choose any application language in the transformed program. At the same time, quite a new approach related to the system conversion is introduced, in which the chunk of data extracted from an old program is edited to make a new conventional structure program that has a logical sequence instead of a Lyee type of declarative program. These features can be realized through the concept of LyeeBELT, which is a set of word-information about the attributes, formulae, and conditions for an independent data item.

The overall workflow of the legacy program transformation is shown in the following.

A critical part in its implementation is the feasibility study (pre-analysis) stage where necessary information is supposed to be secured, and an appropriate plan and policy about the system to be revitalized in the new system environment should be clarified so as to customize the tools accordingly. If the initial process is completed, the mechanical legacy system conversion will be realized by registering the parameters in the tool, and the reestablishment of business knowledge in the LyeeBELT will be enabled. With the regulated business logic on the LyeeBELT, the program maintenance afterwards becomes drastically simplified and stable without the ‘spaghetti’ problem, so that software evolution can be possible.     

Ultra-high voltage electron microscopy: Past,present, and future

High voltage electron microscopy has shown numerous advantages for the study of natural science, including biology, but it is especially useful in materials science. The most important advantage for materials science is in-situ experiments on detailed processes of the same phenomena that occur in bulk materials. For such in-situ experiments, the specimens should be thicker than a few microns to observe the behavior of lattice effect. The maximum observable thickness of the specimens and other advantages markedly increase with increasing accelerating voltage, and since 1965, two 3 MV instruments have been installed. The present paper is mainly concerned with these 3 MV electron microscopes and their applications to new research fields.     

Macroscopic and microscopic changes in the surface layers of annealed and case-hardened steel rollers due to rolling contact

Measurements of the residual stress and observations of the microstructure at the surface and in the subsurface of rollers were performed during rolling contact fatigue tests of annealed 0.45% carbon steel and case-hardened nickel-chromium steel rollers. Compressive residual stresses in annealed rollers were induced by the rolling contact. With case-hardened rollers they were induced by heat treatment prior to the rolling contact fatigue tests. After the rolling contact fatigue tests the compressive residual stresses on the surface of the annealed rollers and in the subsurface of the case-hardened rollers relaxed; a characteristic substructure was formed by the stress cycles, which caused surface failure. It was confirmed that the microcracks leading to surface failure initiate on the surfaces of annealed rollers and in the subsurface of case-hardened rollers.     

Purification and characterization of a strong fibrinolytic enzyme (nattokinase) in the vegetable cheese natto, a popular soybean fermented food in Japan

A strong fibrinolytic enzyme (nattokinase) was purified from the vegetable cheese natto. Nattokinase was extracted from natto with saline and isolated by sequential use of hydrophobic chromatography on Butyl-Toyopearl, ion-exchange chromatography on CM-Toyopearl, and gel-filtration on Sephadex G-50. The isolated protein gave a single sharp band on SDS-PAGE either before or after reduction. The sequence, as determined by automated Edman degradation of the uncleaved molecule and its enzymatically derived peptide, consisted of a total 275 amino acid residues (M.W = 27,728) and exhibited a high homology with the subtilisins. The purified nattokinase digested not only fibrin but also several synthetic substrates. Among the synthetic substrates, the most sensitive substrate was Suc-Ala-Ala-Pro-Phe-pNA for subtilisin. PMSF inhibited both the fibrinolytic activity and the amidolytic activity. The results indicate that nattokinase is a subtilisin-like serine protease.     

How do tufted capuchin monkeys (Cebus apella) understand causality involved in tool use?

Four tufted capuchin monkeys (Cebus apella) were trained to choose from 2 hook-like tools, 1 of which successfully led to collecting food, whereas the other did not because of inappropriate spatial arrangement of the tool and the food. In Experiment 1, all of the monkeys successfully learned the basic task. The monkeys performed successfully with tools of novel colors and shapes in Experiments 2-5. These results demonstrate that the monkeys used the spatial arrangement of the tool and the food as a cue. However, they failed when there were obstacles (Experiment 6) or traps (Experiment 7) on the path along which she monkeys dragged tools. These results may suggest that capuchin monkeys understand the spatial relationship between 2 items, namely, food and. the tool, but do not understand the spatial relationship among 3 items, namely, food, tool, and the environmental condition. The possible role of stimulus generalization is also considered. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A record-linkage study on risk factors for cause-specific infant mortality

Infant death certificates were linked with birth certificates for infants born to residents of Tohoku, Tokai and Kyushu regions in 1989 (n = 409, 679, or about one-third of all births in Japan), to examine the effects of variables, as reported on birth certificates, on cause-specific infant mortality. "Certain conditions originating in the perinatal period" and "congenital anomalies" accounted for nearly 90 percent of neonatal deaths, while "congenital anomalies", "injuries and poisoning" and "sudden infant death" were responsible for about 65 percent of postneonatal deaths. Mortality rates for almost all causes of infant deaths, except injuries and poisonings, increased as birth weight decreased not only in the neonatal period but also in the postneonatal period. This suggests that low birth weight places some infants at higher risk of death, and conditions that lead to low birth weight independently contribute to the risk of infant death. Cox's proportional hazards linear model was used to assess the effects of variables on infant mortalities by causes of death. An extremely strong birth weight effect was noted for "certain conditions originating in the perinatal period" and "congenital anomalies". Being a male infant and late order of birth in multiparity were other risk factors for deaths from "congenital anomalies", while being a male infant, resident of Tohoku region and maternal stillbirth experience related to deaths from "certain conditions originating in the perinatal period". Elevated risks of sudden infant death syndrome (SIDS), of which mortality rate in Japan was considerably lower than those in most developed Western countries, i.e. 0.23 per 1,000 live births in 1989, were associated with low birth weight, being a male infant, low maternal age, late order of birth in multiparity and illegitimacy. Low maternal age, late order of birth in multiparity and illegitimacy, also, related significantly to increased risk of infant deaths for "injuries and poisoning". These results suggest the independent contributions of socioeconomic factors to infant mortality, especially postneonatal mortality, from SIDS, "injuries and poisonings".     

Crystallinity and electrical conductivity of sulfur-containing microcrystalline diamond thin film

Hydrogen sulfide (H₂S) was introduced into a microwave plasma chemical vapor deposition of microcrystalline diamond thin film. Secondary-ion mass spectroscopy showed that sulfur concentration was controlled from 2 × 10¹⁵ to 9 × 10¹⁷ cm^− 3 by controlling the H₂S/CH₄ ratio, while that of hydrogen concentration was around 5 × 10²⁰ cm^− 3 and was independent of the H₂S/CH₄ ratio. Electrical conductance increased linearly as the S concentration increased from 2 × 10¹⁵ to 3 × 10¹⁶ cm^− 3 without significant deterioration of film crystallinity, i.e., the amount of sp² phase did not increase. Non-ohmic conduction was converted to ohmic conduction when the S concentration reached 9 × 10¹⁷ cm^− 3 by increasing the H₂S/CH₄ ratio to 30,000 ppm. This modification was consistent to the formation of a graphitic phase by heavy S-doping, which was identified by Raman spectra and surface morphology.