排序方式: 共有13条查询结果,搜索用时 15 毫秒
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Vance VanDoren 《软件》2010,(2):27-29
工业自动化项目的开展并不总是一帆风顺的,既有项目成功的喜悦,也会面临失败的痛苦。本文特介绍10种项目即将失败的预兆,以及7种系统集成商认可的能继续开展项目的工作方法。 相似文献
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由于控制器带有自整定的功能,使得整定PID回路的典型方法变得前所未有的流行开来。[编者按] 相似文献
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选择控制工程合作伙伴时,仅价格一项,就会让你花费不少。以下内容介绍了资质评审(QBS)程序能给予你怎样的帮助。 相似文献
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Vance VanDoren 《软件》2009,(9):56-56
时间.比例控制是一种高精度的脉冲宽度调制技术。采用该技术的反馈控制器能够将开关量执行器或离散量执行器作为连续执行器使用,从而产生0%至100%之间任意的控制效果。这一技术的窍门在于以一定的时间比例切换执行器的开关状态,以达到理想的控制效果。 相似文献
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上大学的时候,我学习了应用广泛的比例一积分一微分(PID)控制算法。从“理论PID算法”图表中可以看出,该算法由对误差信号执行操作的3个运算符或者说选项组成。控制器可以计算出过程变量和设定值之间误差的积分值和微分值,然后将这两个值与误差叠加,生成一种控制算法。 相似文献
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A four serovar cocktail of Salmonella was inoculated into ground black pepper (Piper nigrum) at different water activity (aw) levels at a starting level of 4–5 log cfu/g and incubated at 25 and at 35 °C. At 35 °C and aw of 0.9886 ± 0.0006, the generation time in ground black pepper was 31 ± 3 min with a lag time of 4 ± 1 h. Growth at 25 °C had a longer lag, but generation time was not statistically different from growth at 35 °C. The aw threshold for growth was determined to be 0.9793 ± 0.0027 at 35 °C. To determine survival during storage conditions, ground black pepper was inoculated at approximately 8 log cfu/g and stored at 25 and 35 °C at high (97% RH) and ambient (≤40% RH) humidity. At high relative humidity, aw increased to approximately 0.8–0.9 after approximately 20 days at both temperatures and no Salmonella was detected after 100 and 45 days at 25 and 35 °C, respectively. Under ambient humidity, populations showed an initial decrease of 3–4 log cfu/g, then remained stable for over 8 months at 25 and 35 °C. Results of this study indicate Salmonella can readily grow at permissive aw in ground black pepper and may persist for an extended period of time under typical storage conditions. 相似文献
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Vance J.VanDoren 《软件》2008,(7)
叠加原理使得反馈控制器能预知线性过程将如何响应控制作用。当反馈控制器能以某种方法预知其目前的控制举动将产生什么作用时,便能控制过程变量趋于所需设定点. 相似文献