DC-RF MOS-FET power inverters, each providing an output power of 3 to 10kW, operating at frequencies of up to 1, 600kHz have actually been used in the RF power supplies in the broadcasting applications with an efficiency of as high as 80_??_90%. However, as the operating frequency increases beyond 10MHz, the power loss caused by the drain-source capacitance of each MOS-FET remarkably increases unless a tank circuit is built containing the drain-source capacitance. Thus, the DC-RF MOS-FET power inverters of single-ended voltage-tuned type are discussed hereafter.
The expressions for the drain efficiency, output power and power gain are given in terms of the ON-resistance, number of MOS-FETs connected in parallel, frequency, phase angle, the wiring inductance, and the load impedance. The calculated values well agree with the measured ones.
Based on the above theory, the tradeoff between the output power and drain efficiency is experimentally and theoretically confirmed to find the optimum design conditions in constructing a DC-RF MOS-FET power inverter.
The phase angle and load impedance are required to be optimized because they affect the power loss. Higher drain efficiency can be obtained for higher load impedance, and however the load impedance is usually specified as low value to increase the output power.
This paper also shows that the drain efficiency is about 70% in a frequency range of 14_??_28 MHz at best if the drain voltage is sinusoidal.

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Current-voltage characteristics of MOSFET can be scaled down in proportion to operation temperature using the temperature-scaling theory that has been proposed by the authors. We have discussed performances of the temperature-scaled MOSFET. It was shown that both the delay time and the power-delay product could be improved for deep-submicron MOSFET in which the velocity saturation occured. By introducing an idea of apparent saturation velocity, the temperature-scaling theory was also valid for the case in which the velocity overshoot occured. The temperature-scaled MOSFET with 0.12μm channel length could be operated at 77K without drain breakdown. The gate delay time of the MOSFET with 0.12μm channel length at 77K was estimated to be 1.7ps. The optimum supply voltage at 77K was considered to be about 1.2V according to the temperaturescaling theory.

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The authors propose a new fault location method which uses neural network to analyze the distribution pattern of the ground wire current along the power line. This method is capable for locating the fault section even for secondary power lines with complicated configurations. Our method has the structure based on the inference process that human experts will analyze the distribution pattern of the current amplitude and phase angle. In locating fault sections, higher precision than ordinary 3-layer neural network or the expert system of our previous development can be obtained.
The proposed neural network comprises 3 sets of 3-layer neural networks which follow the back propagation learning procedure. The 1st and 2nd neural networks calculate the candidate-1 and candidate-2 for the fault section using current amplitude and phase angle distribution patterns respectively. The 3rd neural network then performs final fault location using these candidates and current amplitude distribution pattern. The results evaluated with all possible fault cases indicate that the new method achieves its precision as high as 98.4% even when the measured values differ by 30% from predicted ones with EMTP.

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Recent studies on an improvement of fuzzy controls have shown that fuzzy variables in the antecedent had better exist successively. Then, fuzzy control rules will act mutually and continuously according to the change of the input data. Therefore, the rules had better not leave a blank to all combination of the fuzzy variables. In order to cope with increasing the number of rules, it becomes necessary to contract fuzzy control rules without changing the original control.
The present method defines the “and” conjunction of the antecedent not with the minimum operation but with the product of the grades of the input data. As the result, fuzzy control rules will cover a wider area respectively.
We apply this technique to the control of a tobacco dryer. The fuzzy PD controller in feedback control is represented by a single plane with 4 rules. In contracting the on-off control rules, we propose a coordinate transformation method of the input variables in order to reduce the number of rules without transforming the shape of the control surface.

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This paper presents a new method for power generation planning which takes into account uncertainties of various system parameters as a part of the criterion function. The criterion function involves both the expected values of total system costs and the cost variances of different power plants.
Previously the authors proposed to evaluate these cost variances from the existing power system plans in the form of the solutions to the inverse optimization problem and then applied this procedure to the planning of power system in Japan. However because of the correlation between fuel and facility costs, the costs variances couldn't be determined as specific values.
To overcome this difficulty here, the authors now introduce hydro-power plants into the model as the so-called non-risky elements and focus on the expenditure shares rather than the plant capacity shares, which enables us to obtain more reasonable results.
This improved methodology is applied and the derived cost variances are shown. Further, using the resultant cost variances the authors make Pareto-optimal power generation plans and also demonstrate the robustness of the method to price fluctuations.

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