Chapter 2 introduces the sources and influences on images of all kinds of phase errors, analyzes existing some autofocusing algorithms and lays stress on considerations for application.

论文第二章详细分析了各种相位误差的来源及它们对图像产生的影响，对几种现有的自聚焦算法进行了描述，指出实际应用过程中应该注意的问题。

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Some nations have enough foreign currency reserves, but others will struggle to find new financing to pay their existing debts.

VOA: special.2009.03.13

You could imagine a protein that's existing inside a cell at some level of abundance.

想像一下,在细胞中有一种大量存在的蛋白

耶鲁公开课 - 生物医学工程探索课程节选

Treasury Secretary Tim Geithner says the financial crisis developed in part because the existing system let some companies "shop for the weakest regulator."

VOA: special.2009.06.19

Instead of simply shutting the other 22 bosses in London made sure they invested in rehabilitation services - some at the existing hospitals, some at new facilities - close to people's homes so that the public knew there would still be services available locally.

BBC: Closing NHS services: the impossible job?

When Chevy launched Confidence, it also eliminated or trimmed significantly some existing incentive programs.

FORBES: Lost 'Confidence': Ewanick's Final Move Isn't Working Out

Under some existing schemes, a percentage of the company's profits is given to a local village.

BBC: Herbal medicine