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The feasibility of mixing sandy soil with manure compost was explored for growing muskmelon (Cucumis melonL.). Eight combinations of two compost types (cattle manure with straw (CS) and sheep manure with straw (SS)) mixed in different ratios to sandy soil were used. The mineralisation rate of N and P in CS substrates was higher than that in SS substrates. The reverse was the case for K. The yield and quality of fruit was higher in CS than in SS substrates. CS substrates were therefore better than SS substrates and the optimum rate of addition was a 1:1 ratio of compost to sandy soil.

The multimachine power system stabilizer presented in this paper is based on the theory of optimal, decentralized output feedback control theory. System performance indices are used as a guidance to select the most valid feedback variables and the most effective machine for stabilization. Digital simulations and laboratory tests are made on a three machine power system, which show that the decentralized excitation controllers may contribute much to suppressing system oscillations and enhancing power transmission ability of lines.

ASVG is often expected to operate while the asymmetrical system fault occurs at the ASVG export with some electrical distance. A new firing control method is put forward . This paper describes the realization of DPLFS(Digital Phase Locked Frequency Synthesizer) and its use in the individual phase voltage control of ASVG. The field test reveal that the ASVG can generate a controlled negative phase sequence voltage through 3-phase individual phase voltage control. The computer simulation results show that the ASVG can work continuously owing to this control method even when asymmetrical fault occurs.