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近年来由于电网电压崩溃而引起的电网事故多有发生,因此电网电压稳定性问题引起了广泛关注。区别于以往从发电侧控制的解决策略,文章尝试从负荷侧着手利用可控负荷来提高电网电压稳定性。选取了在都市负荷中比重逐渐扩大的变频空调负荷作为可控负荷范例,参与电网电压稳定性控制。首先对通过对变频空调的原理分析,建立了相应的数学模型,之后针对电网瞬时停电,电网电压跌落等情况,对变频空调的控制策略进行了改进,提出了一种自主控制策略,该控制策略无需通信设备,通过变频空调对电网电压的实时监测,可在电网电压故障情况下,通过主动调节变频空调吸收的功率缓解对电网的有功无功冲击,最后,通过MATLAB仿真分析,对该控制策略进行了验证。 相似文献
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电动机软起动器是近年来在国内出现的新技术,具有节电效率高,软起动特性好等特点。对于大型企业,在动力设备中的应用,节能降耗的意义将十分重大。通过对电动机软启动器节电原理的阐述,及电动机起动技术的分析,提出了应用电动机软起动器的优势和电动机软起动器在动力设备上的实际应用。 相似文献
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针对CRTSI型双块式无砟轨道施工质量控制课题,结合实际案例,做了简单的论述,总结了质量控制策略和措施,共享给相关人员参考。通过分析以往CRTSI型双块式无砟轨道常见施工质量通病,提出有效的质量控制措施,以确保工程实体质量达标。 相似文献
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在对三相异步电动机的几种软启动器的分析比较之后,提出了一种以晶闸管软启动器为核心,利用一台软启动器启动三台盘磨电机的电控系统。实际应用效果证明了该系统的有效性。 相似文献
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介绍了三相异步电动机的几种常用启动方式,并针对造纸厂打浆车间盘磨主电机启动中存在的一些问题,提出了一种以可编程控制器(PLC)为核心,利用1台软启动器启动3台盘磨的电控系统。实际运行效果表明,该电控系统具有可靠性好、性能完善的优越性。 相似文献
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Evaluation of starter diet crude protein level and feeding regimen for calves weaned at 26 days of age. 总被引:2,自引:0,他引:2
The objectives of this study were to evaluate two levels of CP in starter diets offered to calves weaned on d 26 and to compare postweaning intake of starter diets and performance of calves weaned at 26 or 42 d. Forty Holstein calves were housed in individual outdoor hutches and assigned to one of four treatments. Treatments consisted of weaning on d 26 after offering a 20% CP starter diet from d 1, or d 21, or after offering a 25% CP starter diet from d 21, or weaning on d 42 after offering a 20% CP starter diet from d 1 (control). Between d 42 and 84, calves were commingled in outdoor group pens. On d 42, BW of control calves was heavier than that of early weaned calves. On d 84, BW did not differ among treatments. Consumption of starter diet was not affected by the age at which it was first offered. Weaned calves consumed more starter diet than controls from d 29 to 42. Postweaning performance was not affected by increasing CP in the starter diet. Weaning treatment did not affect the incidence of scours. Comparison of CP intakes with current NRC recommendations suggests that CP requirements for young milk-fed calves are adequate. 相似文献
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The effects of cultivating lactic starter cultures with bacteriocin-producing lactic acid bacteria 总被引:1,自引:0,他引:1
The effects of bacteriocins produced by six strains of lactic acid bacteria on 9 mesophilic and 11 thermophilic commercial starter cultures were investigated in mixed cultures of commercial starters with bacteriocin-producing strains in milk. The bacteriocins produced by the test organisms were nisin A, nisin Z, lacticin 481, enterocin AS-48, a novel enterocin, and a novel plantaricin. Mesophilic commercial starters were in most cases tolerant of bacteriocins, with only two of the starters being partially inhibited, one by four and the other by two bacteriocins. The aminopeptidase activities of mesophilic starters were generally low, and only one of the combinations of mesophilic starter-bacteriocin producer gave double the aminopeptidase activity of the starter culture without the bacteriocin producer. Thermophilic commercial starters were more sensitive to bacteriocins than mesophilic starters, with six thermophilic starters being partially inhibited by at least one of the bacteriocins. Their aminopeptidase activities were generally higher than those of the mesophilic starters. The aminopeptidase activities of seven thermophilic starters were increased in the presence of bacteriocins, by factors of up to 9.0 as compared with the corresponding starter cultures alone. Bacteriocin-producing strains may be used as adjunct cultures to mesophilic starters for the inhibition of pathogens in soft and semihard cheeses, because mesophilic starters are rather tolerant of bacteriocins. Bacteriocin producers may also be used as adjunct cultures to thermophilic starters of high aminopeptidase activity, more sensitive to lysis by bacteriocins than mesophilic starters, for the acceleration of ripening in semihard and hard cheeses. 相似文献
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介绍电子软启动器在不需调速的水箱拉丝机中的应用。软启动方式与传统启动方式几方面的对比结果表明 :用软启动器启动可降低对供电电网质量的影响 ,改善电机启动特性 ,减小启动对机械设备的冲击 ,降低设备运行和维护成本等 ,是今后发展的方向 相似文献
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以羊肉为原料不添加发酵剂、添加市售发酵剂和复合发酵剂(植物乳杆菌与肉葡萄球菌混合发酵剂比为1∶3)采用同种工艺生产三组发酵香肠。研究三组羊肉发酵香肠发酵和干燥成熟过程中的p H、Aw、色差、亚硝酸盐(NIT)含量变化以及成品的质构特性。结果显示:发酵过程中,三组发酵香肠的p H、Aw和e值均下降,混合发酵剂组p H迅速降低为4.7,低于对照组和市售发酵剂组,其NIT含量为0.66mg/kg,低于对照组和市售发酵剂组的0.79、0.8mg/kg;成熟结束时,三组的p H和e值开始上升,混合发酵剂组的Aw下降极显著(p<0.01)快于市售发酵剂组和对照组,并且三组各项质构指标除黏聚性外均差异极显著(p<0.01),最终对照组、市售发酵剂组、混合发酵剂组发酵香肠的NIT含量分别为1.38、1.46、1.26mg/kg。整体上,混合发酵剂香肠品质优于其他两组。 相似文献