Microstructure and phase transformation in a highly non−Ohmic metal oxide varistor ceramicThe degradation phenomena caused by dc and ac biasing in non-Ohmic ZnO ceramics are studied from the viewpoints of voltage (V)-current (I) characteristics, dielectric properties, and thermally stimulated current (TSC). As a result, it is concluded that the degradation caused by dc biasing is attributed to the asymmetrical deformation of Schottky barriers, due to ion migrations in Bi z 0 3rich intergranular layers and in the depletion layers of the Schottky barriers; and that the degradation caused by ac biasing is attributed to the symmetrical deformation of the Schottky barriers, due to ion migration in the depletion layers of the Schottky barriers. Also, the relationship between the thermal runaway life of non-Ohmic ZnO ceramics and biasing conditions, such as biasing temperature and bias voltage, is obtained.
The differential-phase-shift (DPS) and the coherent-one-way (COW) are among the most practical protocols for quantum cryptography, and are therefore the object of fast-paced experimental developments. The assessment of their security is also a challenge for theorists: the existing tools, that allow to prove security against the most general attacks, do not apply to these two protocols in any straightforward way. We present new upper bounds for their security in the limit of large distances (d 50 km with typical values in optical fibers) by considering a large class of collective attacks, namely those in which the adversary attaches ancillary quantum systems to each pulse or to each pair of pulses. We introduce also two modified versions of the COW protocol, which may prove more robust than the original one.
In development, design and operation of photovoltaic power generation systems, a technique for constructing I-V curves under different levels of solar irradiance and module temperature condition susing basic characteristic values of photovoltaic modules is required.For this purpose, we have already developed a practical I-V curve construction method and are using it in the evaluation of the output of a photovoltaic power generation system as well as in the core section of a simulation program to determine the amount of powor generated by a photovoltaic power generation system. This time, we have developed an I-V curve construction method based on a different viewpoint from the above, namely,we developed an I-V curve construction method using current-voltage characteristic equations under photovoltaic cell irradiated conditions. Using this method, we can obtain I-V curves not only in the first quadrant but also in the second and fourth quadrants.In this report, we discuss the outline of the I-V curve construction method using current-voltage characteristic equations of photovoltaic celles, as well as verification test results and application examples
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