bifocal 中文意思是什麼
bifocal
解釋
adj. 形容詞 1. 【物理學】雙焦點的。2. (望遠鏡等)遠近兩用的。
3. 有二重觀點的。
n. 名詞 〈pl. 〉 雙光眼鏡,遠近視兩用眼鏡;雙焦點透鏡。
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Lt ' s definitely a modern - day bifocal lens,
這肯定是今天才有的雙焦鏡片 -
Focusing properties of gaussian beams passing through a bifocal lens
高斯光束通過雙焦透鏡的聚焦特性 -
Third, this dissertation analyzes the complicacy of result size estimation problem for xml structure based query optimization compared to its counterpart in traditionally relational database, and proposes a full - featured result size estimation algorithm for xml query, sxm. for simple path expression query, this dissertation proposes a dynamic synopsis model for xml data based on the concept of f - stable and b - stable, xmap. for complicated path expression query, this dissertation adopts an improved bifocal sampling method for result size estimation
第三,分析了xml結構化查詢優化中的查詢代價估計問題與傳統關系型數據庫中的查詢代價估計問題的區別,提出了一套完整的xml結構化查詢代價估計體系sxm ,包括對簡單路徑表達進行查詢代價估計的動態xml數據統計模型xmap ,對復雜路徑表達進行查詢代價估計的雙焦點例舉法,以及對值匹配條件進行查詢代價估計的基於小波的多維直方圖方法,並能將多種查詢表達的查詢代價估計結果結合在一起,以給出一個完整的xpath查詢的代價估計。 -
Detailed numerical results for a pgsm beam passing through a bifocal lens are presented. it implies that the degree of polarization is no longer uniformly polarized in general and propagation - induced polarization changes depend on the beam parameters and system parameters, such as beam coherence parameter
通過對雙軸透鏡系統進行的數值計算表明, pgsm光束光場的偏振不再是均勻偏振,光束的偏振特性與光束參數和光學系統參數有關,不同相關狀態下場點的偏振度不同。
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