Generalized integrator was used to realize static error free tracking control of positive and negative sequence current under two-phase static coordinate.

并采用广义积分器原理实现对三相电流在两相静止坐标下的控制，实现了正负序电流的无静差跟踪控制。

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The band is labeled with a tracking number, and there is a phone number on the band for people to call for free, to report a banded bird they've found or recaptured.

这只手环上有一个追踪号码，还有一个人们可以免费拨打的电话号码，举报他们发现或捕获的标记雀鸟。

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Though many of its classes and services, like progress tracking, require a paid membership, some are free.

虽然许多班级和服务，比如进展跟踪等是需要会员付费的，但仍有很多项目免费。

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Dr. Rakesh Jain, psychiatrist at the University of Texas Medical School at Houston, uses a free mood tracking app called Moody Me by MedHelp.

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Users can also sign up to get a free daily newsletter tracking media news and staff changes.

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SmartRecruiters: a no-cost (yes, free) cloud-based applicant tracking and social recruiting system which lets recruiters post jobs on Facebook with the click of a button.

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