[en] Published in summary form only

[en] For ⁶⁰Co (Type S) and ⁵⁴Mn (Type M), for which the whole-body content can be measured, it is possible to minimise the errors of the estimated effective doses caused by uncertainty of the activity median aerodynamic diameter (AMAD) by assuming the AMAD as 5 μm and by measuring the body content on day 5 after inhalation. For the radionuclides to be measured in the lung content, e.g. ²³⁹Pu (Type S), it may be necessary to estimate the AMAD, because the lung burdens on any day are not always proportional to the whole-body content which reflects the effective doses. There is no problem in assuming the AMAD to be 5 μm for external counting and for urinalysis of Type F compounds, because of the rapid absorption of such compounds into the blood and the same biokinetics. The breathing rate is assumed to be 1.2 m³h^-1. (author)

[en] One of the fundamental concepts of the draft international standard, IEC 61508, is target failure measures to be allocated to Electric/Electronic/Programmable Electronic Safety-Related Systems, i.e. Safety Integrity Levels. The Safety Integrity Levels consist of four discrete probabilistic levels for specifying the safety integrity requirements or the safety functions to be allocated to Electric/Electronic/Programmable Electronic Safety-Related Systems. In order to select the Safety Integrity Levels the draft standard classifies Electric/Electronic/Programmable Electronic Safety-Related Systems into two modes of operation using demand frequencies only. It is not clear which modes of operation should be applied to Electric/Electronic/Programmable Electronic Safety-Related Systems taking into account the demand-state probability and the spurious demand frequency. It is essential for the allocation of Safety Integrity Levels that generic algorithms be derived by involving possible parameters, which make it possible to model the actuality of real systems. The present paper addresses this issue. First of all, the overall system including Electric/Electronic/programmable Electronic Safety-Related Systems is described using a simplified fault-tree. Then, the relationships among demands, demand-states and proof-tests are studied. Overall systems are classified into two groups: a non-demand-state-at-proof-test system which includes both repairable and non-repairable demand states and a constant-demand-frequency system. The new ideas such as a demand-state, spurious demand-state, mean time between detections, rates of d-failure and h-failure, and an h/d ratio are introduced in order to make the Safety Integrity Levels and modes of operation generic and comprehensive. Finally, the overall system is simplified and modeled by fault-trees using Priority-AND gates. At the same time the assumptions for modeling are described. Generic algorithms to estimate hazardous-event frequencies are derived based on the fault-trees. Thus, new definitions regarding modes of operation for the allocation of Safety Integrity Levels and shortcut methods for estimation of hazardous-event frequencies are proposed

[en] Fault tree analysis (FTA) is generally accepted as an efficient method for analyzing system failures. It is well known that a fault tree (FT) is equivalent to a minimal cut set fault tree with all minimal cut-AND structures. The minimal cut-AND structure is an AND conjunction of an output and all inputs that compose a minimal cut set. For the structure, the failed state of the output becomes true when all failed states of inputs exist simultaneously. There are cases where the output of the minimal cut-AND structure depends not only on all failed states of inputs but also on the sequence of occurrences of those failures. This sequential failure logic (SFL) is equivalently expressed with Priority-AND gates in FTA, where inputs to the gates have constant failure and repair rates. A probabilistic model for analysis of SFL was proposed and equations with multiple integration for arbitrary number of inputs were derived from the model. However, it is usually difficult to solve the multiple integration when the number of inputs exceeds a certain range. This paper presents analytical solutions of the probability that the output is in a failed state at time t and the statistically expected number of failures of the output per unit time at time t for the special case where inputs are characterized by common failure and repair rates. In addition, the analysis of FT involving SFL is demonstrated by means of software Mathematica

[en] A method is described to improve the plateau characteristics of a self-quenching GM counter by γ-irradiation. (Auth.)

[en] In order to determine the best technique for long leg angiography, the authors evaluated three separate variables: volume of contrast material injection (aortic bifurcation, external iliac artery); and arterial inflow occlusion. In a prospective, randomized fashion, 52 patients were studied. Two blinded examiners reviewed all angiograms for the quantity of arterial filling (i.e., the need for additional filming) and for the quality of arterial filling (i.e., the best angiogram in terms of appearance). The authors found that optimal cut-film, long leg angiography was performed by using high volumes (60 mL) of contrast material injected below the pelvic vessels with or without inflow occlusion

[en] Amounts of spontaneous spin splittings were estimated from low-temperature magnetoresistances in two-dimensional electron gases created at In_0.75Ga_0.25As/In_0.75Al_0.25As heterojunctions under a gate bias. Typical sheet electron densities and mobilities in the raw wafers were ∼1.0x10¹²/cm² and 2 - 5x10⁵cm²/Vs at 1.5 K, respectively. A maximum spin-orbit coupling constant α_zero of ∼30(x10^-12eVm) was obtained for the van der Pauw sample. In gated Hall-bar samples, a decrease in the α_zero value with decreasing gate voltage (V_g) was first confirmed in a normal heterojunction. The main origin for such a large α_zero, which is a few times larger than any previously reported, was found to be a structure-dependent so-called interface contribution in the Rashba term. [copyright] 2001 American Institute of Physics

[en] This paper reports on a compact RFP (Reversed Field Pinch) machine TPE-2M which was constructed, and the operation test is now under way. It was designed to research methods of confinement improvement of RFP plasma. Dimension of induced plasma has the major/minor radii 73cm/18. 8 cm. The vacuum vessel is made of thin stainless steel. The stabilizing shell is made of 40mm thick aluminum and is double layer structured to minimize the error field at the shell cut. The poloidal coil for inducing the plasma current (> 200kA) is coupled with an iron core of 0. 7Vs flux swing. An axisymmetric poloidal divertor is provided to control the particle and heat exhausts from edge plasma. A power supply system of 1 MJ energy is connected to each coil in order to obtain a fast rising and long duration pulse. The power supply system as well as the vacuum system and the data acquisition system are computer controlled. Preliminary bank test shows the machine performance is sufficient for the objective plasma experiment. Expected plasma temperature and sustained time are 0. 5keV and 5ms respectively

[en] Moessbauer spectra of ⁵⁷Co doped into CaF₂ single crystals are decomposed into a single line and a quadrupole doublet. The former is ascribed to Fe²⁺ ions on Ca²⁺ sites with cubic symmetry, and the latter to Fe²⁺ ions on axially symmetric interstitial sites associated with an adjacent cation vacancy. γ-irradiation further produces a new line which arises from Fe²⁺ ions on interstitial sites with cubic symmetry. When the irradiated crystals are quenched from 500⁰C, only two lines appear which arise from Fe²⁺ ions on interstitial sites associated with two neighbouring cation vacancies. (author)

[en] We have measured the anisotropic charge dynamics in the 90-K phase of YBa₂Cu₃O_y, and have found that the out-of-plane scattering time is more than five times shorter than the in-plane scattering time. Another anomal is the rapid enhancement of the in-plane scattering time below T_c. Our magneto-thermopower measurement has revealed that the enhancement also occurs in the mixed state. These two features are never ovserved in other layered superconductors, such as organic BEDT salts or Sr₂RuO₄; thus, they can be direct evidence for the non-Fermi-liquid behavior of high-T_c cuprates