The application of the simple fuel pin transient and melting model to thermal-hydraulics in LMFBR subassembly

A simple conduction model with phase change has been developed for the transient analysis of a reactor fuel pin based on lumped parameter techniques. The purpose of this analysis is to provide a simple useful tool to obtain the general information about fuel and clad leaning into the cooling transients and melting. Such a simple fuel and clad thermal transient model is particularly useful to multichannel analysis where conventional conduction computer codes require considerable computing time and storage space. At the present, this formulation is being employed for the analysis of sodium thermohydraulics, sodium voiding, and melting of cladding and fuel in a subassembly of a fast reactor core. A detailed analysis of the predicted coolant, fuel and cladding thermal transients leading into sodium voiding and fuel pin melting has been made in comparison with the results of various in-pile experiments and with the predictions from the existing more complicated codes.     

Analysis of dynamic-characteristic curve of tunnel diodes

A ?step? in the negative-resistance region of the voltage/current characteristic curve of an oscillating tunnel diode is theoretically analysed from the viewpoint of the conservation of energy. Tunnel diodes IN3219A and D4168D were experimentally investigated in the L and X bands. This step is attributed to the power conversion from d.c. to a.c.     

Dynamic Capturing Strategy for a 2-D Stick-Shaped Object Based on Friction Independent Collision

This paper proposes dynamic capturing strategies where a 2D stick-shaped object with both translational and rotational velocity is completely stopped by two robotic fingers. We first show the fingertip position and the object orientation for generating a desired velocity of the object under the friction independent collision. Once the object results in a pure translational motion whose direction is perpendicular to the longitudinal axis of object, it is guaranteed that two fingers can always capture the object irrespective of friction coefficient. By using this nature, we show both 2-step and 3-step capturing strategies for a 2D stick-shaped object whose width is negligibly small. The 3-step capturing strategy can guide the object in an arbitrary direction, while the 2-step one can do it only in a particular direction. The proposed strategies are demonstrated by experiments for verifying our idea.     

Early detection of the invasive alien plant Solidago altissima in moist tall grassland using hyperspectral imagery

We assessed aerial hyperspectral imagery with high spatial (1.5 m) and spectral (8.9 nm) resolutions for detecting and mapping the early invasion by Solidago altissima of understory vegetation in moist tall grassland. Generalized linear models (GLMs) were constructed to predict S. altissima occurrence using 1.5 m pixels from hyperspectral data collected during the spring when understory vegetation was directly observable from above. A data set of presence–absence derived from percentage cover data was used for the analyses. The values of the area under the receiver operating characteristic (ROC) curve (AUC) ranged from 0.77–0.87 in the validation data set. Three minimum noise fraction (MNF) bands differentiated S. altissima in the best-performing model (selected based on Akaike's information criterion) for the occurrence of S. altissima. The results suggest that the aerial hyperspectral images obtained during spring before the seasonal development of the grass canopy are useful for the early detection and mapping ofS. altissima invading moist tall grassland.     

Numerical electromagnetic field analysis on lightning surgeresponse of tower with shield wire

Lightning surge characteristics of a transmission line comprising a tower, a shield wire and phase conductors are studied with the help of NEC-2. A tower struck by a lightning stroke behaves as an antenna until a traveling wave makes several roundtrips in the tower. During this interval, the tower footing impedance appears to be higher than the footing resistance, and the coupling coefficient between a shield wire and a phase conductor is much lower than that in the TEM mode. These affect the estimation of insulator voltages of transmission towers subject to lightning currents having short rise times. On the basis of these findings, the parameters in the multistory tower model, which has been used widely in EMTP multi-conductor analyzes, are newly proposed     

Numerical electromagnetic analysis of impulse voltage measuringsystems

The unit step response (USR) of lightning impulse voltage measuring systems is numerically calculated with the help of the Numerical Electromagnetic Code (NEC-2), which calculates the three-dimensional electromagnetic field around conducting wires. The accuracy of this analysis is proved satisfactory through comparison of the results of measurement with calculation. The advantage of this method is that the influence of the geometry of the circuit can automatically be calculated without evaluating stray capacitance in the system. Therefore, this method of analysis can be applied to the development of an impulse voltage divider, or in analyzing the influence of elements of a USR measuring circuit. The influence of the shield ring attached to a resistance divider, and of the vertical metal sheet in the IEC-recommended USR measuring circuit on the USR waveform is analyzed as an example     

Albumin stabilizes (–)‐epigallocatechin gallate in human serum: Binding capacity and antioxidant property

(–)‐Epigallocatechin gallate (EGCg) is the major component of green tea and is known to show strong biological activity, although it can be easily oxidized under physiological conditions. In this study, we indicate that EGCg is stable in human serum and that human serum albumin (HSA) stabilizes EGCg under aerobic condition. Although EGCg is usually decomposed within 1 h in aqueous solution at neutral pH, EGCg in serum and phosphate buffer (pH 7.4) containing HSA was stable over 1 h, even at neutral and slightly alkaline pH. Under these conditions, EGCg binds to HSA non‐covalently. The sulfhydryl group acts as an antioxidant for EGCg oxidation. Incubation of EGCg with HSA is accompanied by the oxidation of a free sulfhydryl group in HSA. These results suggest that the antioxidant property and the binding capacity of HSA contribute to the stabilization of EGCg in human serum.     

Generation of high-repetition-rate WDM pulse trains from anarrayed-waveguide grating

We present what we believe to be the first demonstration of femtosecond pulse train generation from an arrayed-waveguide grating. Terahertz-rate bursts of femtosecond pulses are produced with the rate determined by the arrayed-waveguide delay spacing     

AN EXPERIMENTAL AND STATISTICAL INVESTIGATION OF SURFACE FATIGUE CRACK INITIATION AND GROWTH

Surface fatigue crack studies were carried out and statistically analysed from rotating bend fatigue tests in the high cycle region for three metals, copper, stainless steel and mild steel with four ferrite grain sizes. Quantitative observations of the initiation and growth behavior, including coalescence of closely spaced cracks, are discussed and a limiting condition for coalescence is proposed. Statistical properties of initiation, propagation and propagation rate of surface cracks are examined and the effect of different metals and grain sizes is discussed.