STORAGE PROPERTIES OF PRIMAL CUTS OF HOT- AND COLD-BONED BEEF

One side from each of 10 carcasses was selected for electrical stimulation and hot-boning within 1 h postmortem while the opposite side was chilled for 48 h at 2 to 3 C before boning. Ten boneless primal cuts were removed from the hot- and cold-boned sides. Each cut was evaluated for lean color, fat color and shape. Hot- and cold-boned primal cuts were vacuumized and stored for 20 days at 2 to 3 C. After the storage period, all cuts were again evaluated for lean and fat color and shape. Weight loss during storage was calculated for each cut. After 20 days of storage, hot- and cold-boned cuts did not differ significantly in lean color; hot-boned cuts had fat that was significantly whiter than that of cold-boned cuts; cold-boned cuts were more nearly normal in shape than were hot-boned cuts; and hot-boned cuts retained their vacuum longer and lost considerably less weight during storage than cold-boned cuts.     

Effect of Electrical Stimulation and Postmortem Boning Time on Sensory and Cookery Properties of Ground Beef

Ground beef was prepared from electrically stimulated and nonstimulated sides of 24 U.S. Utility grade carcasses that were boned 1, 3 or 24 hr postmortem. Postmortem electrical stimulation had no negative effects or, the physical, sensory or cooking properties of ground beef patties. Time of boning had significant effects on percent height change during cooking, total cooking loss, tenderness, and juiciness. As cooning time increased, the effects on the traits were negative.     

永磁同步电机驱动系统逆变器容错重构控制

针对永磁同步电机(PMSM)驱动系统在逆变器故障状态下的容错控制,讨论了容错逆变器的拓扑结构,分析了六开关三相逆变器和四开关三相逆变器驱动系统输出电压空间矢量及其对系统性能的影响。研制了一个基于常规六开关逆变器的容错辅助控制电路,实现了容错逆变器在故障下的重构。针对PMSM直接转矩控制系统的实验研究,验证了容错辅助控制电路设计的正确性,证明采用容错逆变器可实现驱动系统的不间断运行。