main field focusing 中文意思是什麼
main field focusing
解釋
主場聚焦-
In this thesis, first, reasons and factors for the stability of loose rock dams were summarized according to the field surveys and certain expert ' s experiences. then, researches on block stability problems were reviewed, and according to the relationship between grain size and incipient velocity, it is found that the block weight is in direct proportion to 6 - 9 power of incipient velocity, and 50 % increase of the velocity will result in about 40 times change of the block weight. after that, experiments were conducted in a flume, focusing on the relationship between incipient velocity and some main factors including block weight, water depth over the dam, cross - section size, block material and river bed material
本文首先根據散拋石壩損毀情況的現場調查資料，結合有關專家多年的整治經驗，總結出壩體的損毀原因及影響因素；對現有塊體穩定性的研究成果進行回顧和總結，並針對散拋石壩的直接損毀現象，結合山區河流的水流、地形特點，利用塊體粒徑與起動流速的關系，提出塊體穩定重量與起動流速高次方成正比的概念，流速50的增長可能導致塊體穩定重量接近40倍的變化；通過二維變坡水槽試驗，研究了壩體穩定的主要影響因素，包括塊體重量、壩頂水深、斷面尺寸、塊體材料（塊石和卵石兩種） 、護底等，結果表明對于山區河流，試圖僅僅通過增加壩體單個塊體重量或斷面尺寸來提高壩體穩定性效果甚微；最後，根據西部地區的自然、經濟、交通等條件，提出可以採用柔性混凝土鉸鏈體等一類整體性較好的護面層作為散拋石壩的防沖毀措施，以期取得良好的工程效果。 -
Based on analyse of parameters which used to evaluate laser beam quality at present and according to the main properties which influence on laser manufacturing, beam focus characteristics parameter is put forward as the stander parameter to evaluate beam quality, because the foundmental advantage of laser beam applied in industral field is that laser beam can achieve high energy intensity through focusing
論文在總結目前存在的評價激光光束質量參數的基礎上，根據對影響激光製造的主要光束特性參數的分析，以光束空間特性為核心，提出用光束聚焦特徵參數值作為評價激光光束質量的參數。因為激光作為能源能夠在工業領域廣泛應用的根本優勢就在於它可以通過聚焦獲得極高的能量密度，而值恰恰表徵了實際光束的可聚焦能力。
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