In order to detect steel bars and power cables inside pliable plastic conduit tubes buried in concrete walls and slabs during the renovation of old buildings, we have developed a new nondestructive inspection (NDI) system. This system, which enables high precision detection and easy handling at low cost, works by measuring the impedance due to the inductance change of a solenoid coil which exposes the test material to a magnetic field. In this system, the solenoid coil is connected to a compensating capacitor with a series-resonant circuit to reduce the impedance and multiply the impedance change by increasing the quality factor, Q, i.e., the ratio of the inductive reactance, ?L, to the coil resistance, R, which contributes to improving the signal-to-noise ratio for detection. This paper describes the validity of the design method of this NDI system. Firstly, the fractional deviation of inductance, ?, the inductance changes between with and without a steel bar and power cables were analyzed. The deviations due to the eddy currents and magnetization induced in the steel bars and power cables were computed through 3-D magnetic field analysis taking eddy currents at 5, 40 and 800 kHz into account. Secondly, the rates of change of impedance (RCIs) and phase angles were measured with the impedance meter of the newly developed NDI system. This system was designed so that the value of became roughly 200 and the resonance frequencies became about 5, 40 and 800 kHz. For steel bars, the predicted RCIs, which were calculated from the computed s multiplied by the designed Q factor, roughly matched those measured. In case of power cables, the tendency of predicted RCIs were roughly in accord with those measured. The validity of the design method's detecting system was verified. In addition, the analysis and measurement proved that this NDI system can distinguish steel bars from power cables by the polarity of the phase angle.
A measurement method of very-fast-voltage rise curves due to gap discharge using the coupled transmission lines was examined to discuss a electromagnetic noise source from a viewpoint of electromagnetic compatibility (EMC). The measurement system consists of a distributed constant line system, because the voltage transients were very rapid. A characteristic of the gap electrode, which has a matched impedance for the distributed constant line system, was investigated in the frequency range below 5 GHz. The voltages of power source in experiment were 510 V and 800 V because the Paschen's law holds stability in air condition. As a consequence of the experiment with this measurement system, the measurement method made it possible to observe the very fast rise curves of about 100 ps.
It is well known that, in a color CRT, color change occurs as a result of the magnetization of the shadow mask and frame in the enviromental magnetic field. In order to clarify the influence of the mask and frame quantitatively, We analyzed the magnetization by integral equation method when a shadow mask and frame were subjected to an ambient field. We calculated the electron beam trajectories by using the derived magnetic field distributions, and computed the miss-landing to evaluate the color change quantitatively. The results of the numerical analysis agree well with experiment, and aid in relating the shielding to the miss-landing.
Magnetically shielded rooms (MSRs) with materials of high permeability and active shield systems have been used to shield magnetic noise for biomagnetic measurements up to now. However, these techniques have various disadvantages. Therefore, we have developed a new shielding system composed of shielding panels using an active compensation technique. In this study, we evaluated the shielding performance of several unit panels attached together. Numerical and experimental approaches indicated that the shielding factor of a cubic model composed of 24 panels was 17 for uniform fields, and 7 for disturbances due to car movement. Furthermore, the compensation space is larger than that of an ordinary active system using large coils rather than panels. Moreover, the new active compensation system has the important advantage that panels of any shape can be assembled for occasional use because the unit panels are small and light.
We calculate nuclear-polarization energy shifts for hydrogenlike $^{208}_{~82}$Pb$^{81+}$. A retarded transverse part as well as the Coulomb part is taken into account as the electromagnetic interaction between an electron and the nucleus. With a finite charge distribution for the nuclear ground state and the random-phase approximation to describe the nuclear excitations, we obtain nuclear polarization energy of the $1s_{1/2}$ state as --38.2 (--37.0) meV in the Feynman (Coulomb) gauge. For the $2s_{1/2}$, $2p_{1/2}$ and $2p_{3/2}$ states, they are --6.7 (--6.4), --0.2 (--0.2) and +0.0 (+0.0) meV, respectively. The seagull term in the two-photon exchange diagrams is shown to be quite important to obtain the gauge invariance of the nuclear polarization energies.
We present a relativistic chiral mean field (RCMF) model, which is a method for the proper treatment of pion-exchange interaction in the nuclear many-body problem. There the dominant term of the pionic correlation is expressed in two-particle two-hole (2p-2h) states with particle-holes having pionic quantum number, Jπ. The charge-and-parity-projected relativistic mean field (CPPRMF) model developed so far treats surface properties of pionic correlation in 2p-2h states with Jπ = 0− (spherical ansatz). We extend the CPPRMF model by taking 2p-2h states with higher spin quantum numbers, Jπ = 1+, 2−, 3+, … to describe the full strength of the pionic correlation in the intermediate range (r > 0.5 fm). We apply the RCMF model to the 4He nucleus as a pilot calculation for the study of medium and heavy nuclei. We study the behavior of energy convergence with the pionic quantum number, Jπ, and find convergence around Jπmax = 6−. We include further the effect of the short-range repulsion in terms of the unitary correlation operator method (UCOM) for the central part of the pion-exchange interaction. The energy contribution of about 50% of the net two-body interaction comes from the tensor part and 20% comes from the spin-spin central part of the pion-exchange interaction.
MACROMOLECULES C248concave surface.The 2-5A molecule is accommodated in the concavity and interacts with ankyrin repeats 2 to 4. Two structurally equivalent 2-5A binding motifs are found at repeats 2 and 4. The structural basis for 2-5A recognition by ANK is essential for designing stable 2-5As with a high likelihood of activating RNase L.
