Verification of Characteristics of a Boost‐Type Matrix Converter for a Three‐Phase Four‐Wire System

This paper describes an improvement to the control method of a boost‐type matrix converter (MC) for a three‐phase four‐wire system. The system is intended for use in a stand‐alone power source with a constant voltage and frequency. However, the conventional method is not able to control the output voltage with a low power‐factor load. To resolve this problem, we propose a new control method by using a MC and revising the conventional control method.     

A Study on Influence of Ramp Event of Aggregated Power Output of Photovoltaic Power Generation on Electric Power System Frequency

This paper examines the influence of aggregated power output fluctuation of photovoltaic power generation system (PVS) on the power system frequency focusing on ramp events of aggregated PVS power output. A numerical simulation model of economic load dispatching control (EDC) and load frequency control (LFC) is used together with a PVS power output forecasting model and a unit commitment (UC) scheduling model developed in our preceding study. As a result, in the case of ramp event with long duration and high ramp rate, the frequency violation occurs when the power output of controllable generators with high load‐following capability reaches to upper/lower limit even if the power output of low load‐following capability generators is still available. If the load dispatching scheme is tentatively changed from the conventional EDC using an equal incremental fuel cost rule to, for example, a dispatching policy based on the capacity without the consideration of fuel cost, the aggregated load‐following capability can be kept, avoiding the frequency violation.     

ATP and Creatine Phosphate Breakdown in Spiked Plaice Muscle during Storage, and Activities of Some Enzymes Involved

The onset of rigor-mortis of plaice Puralichthys olivaceus spiked at the brain started much faster at 0°C than at 10°C. Correspondingly, ATP and creatine phosphate breakdown and lactic acid accumulation in the muscle were faster at 0°C. ATP concentration was constant at 5 μmol/g until creatine phosphate decreased from the initial conccntration at around 20 μmol/g to 5 μmol/g, irrespective of storage temperature. Simultaneously, lactic acid accumulated, slowly at first, until ATP concentration started decreasing, and then quickly accompanying the full-rigor state. Activities of the enzymes involved in ATP and creatine phosphate consumption-myofibrillar and sarcoplasmic AT-Pases and creatine kinase-were temperature-dependent, and decreased with decrease in temperature.     

Effect of Storage Temperature on Rigor-Mortis and ATP Degradation in Plaice Paralichthys olivaceus Muscle

Live specimens of the plaice Paralichthys olivaceus were spiked at the brain, stored at various temperatures ranging from 0° to 20°C and examined for changes in rigor tension and ATP degradation in the muscle. The ATP degradation rate was clearly slower at 5–15°C than at WC, resulting in retardation of rigor- mortis onset at the former temperatures. Lactic acid accumulation in the muscle correlated well with the decrease of ATP. The muscle showed an ATP concentration of 3 μmol/g and “rigor index” (full rigor = 100%) at 30% when lactic acid increased up to 30 μmol/g at most storage temperatures. The muscle showed full rigor when ATP completely disappeared and lactic acid attained the maximum plateau (40–50 μmol/g).     

Temperature-Dependency of Rigor-Mortis of Fish Muscle: Myofibrillar Mg2+-ATPase Activity and Ca2+ Uptake by Sarcoplasmic Reticulum

Myofibrillar Mg²⁺-ATPase activity of plaice and red sea bream increased with increase in reaction temperature and Ca²⁺ concentration. However, temperature decrease tended to lower Ca²⁺ sensitivity of Mg²⁺-ATPase activity. While it was assumed that spiked fish muscle was relaxed and the myofibrillar Ca²⁺ concentration was low, the progress rate of rigor-mortis correlated well with Mg²⁺-ATPase activity in the presence of a few micromolar Ca²⁺ at 0°C. Correspondingly, it was found that Ca²⁺ uptake by plaice sarcoplasmic reticulum decreased with the decrease in reaction temperature. These results strongly suggest the acceleration of fish rigor-mortis at 0°C is due to the increase of Ca²⁺ concentration in myofibrils during storage at this temperature.