The business activities of NTT Power and Building Facilities Inc. (NTT-F) consists of engineering and management for NTTs telecommunications system. A maintenance work related to batteries occupies about 1/4 of the entire telecommunications power system maintenance work. Moreover, a large number of valve regulated lead acid (VRLA) batteries have been installed and maintenance work of these batteries will increase in the future. To reduce this maintenance work, NTT-F has developed technology to evaluate the condition of a battery by discharging under a real load condition and to measure deterioration simply by measuring internal resistance of a single cell. NTT-F is scheduled to improve the efficiency of battery maintenance work by systematically using this technology.

The magnetostatic resonance absorptions for an axially magnetized single crystal of YIG rod, [110] oriented, are observed in a waveguide and a cavity at 9.45 GHz. For the applied magnetic field ranging from 2800 to 3400 Oe resonance absorptions due to the dominant and third modes are observed but the second mode is not excited. The separation of these modes is conducted by comparing the transmitted power with the reflected microwave power pattern. For the dominant and third modes the relations between the field deviation, ΔH, from the cutoff field and the standing wave number n for each absorption are in good agreement between the theoretical and experimental values in a wide range of dc magnetic field. When the entire rod is inserted into the center of a waveguide or a cavity only the absorptions due to modes associated with an odd number, n, are observed for both dominant and third modes

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