sampling variance 中文意思是什麼

sampling variance 解釋
采樣方差
  • sampling : n. 1. 取樣（品），取標（本）〈指行動或程序〉。2. 樣品，標本。3. 剽竊拼湊歌曲。
  • variance : n. 1. 變化，變動，變更；變度，變量；【統計】（平）方（偏）差。2. （意見等的）相異；不和，沖突，爭論。3. 【法律】訴狀和供詞的不符。
  1. Besides, this paper adopts the random finite element method, uses geometric and physical mechanical parameters that are relevant to lining weight of surrounding rock, coefficient of lateral pressure, height or buried depth of vertical loading, elastic resistance coefficients of surrounding rock, elastic modulus of support structure, unit weight of concrete, thickness of the structure as well as torsional strength and compression strength of concrete and etc., as random variables, applies the monte - carlo method to sampling by computer, preliminarily evaluates the reliability of bearing capacity and stability of molded concrete lining of the xuefeng mountain tunnel, and obtains the related displacement of the lining, mean value and variance of internal force, and computed the reliability index of lining structures

    此外，本文採用隨機有限元方法，將圍巖容重、側壓力系數、垂直荷載高度或埋深、圍巖的彈性抗力系數、支護結構的彈性模量、混凝土容重、結構的厚度以及混凝土的抗扭與抗壓強度等與襯砌結構有關的幾何與物理力學參數作為隨機變量，應用蒙特卡洛理論進行計算機隨機取樣，對雪峰山隧道模注混凝土襯砌的承載力與穩定性的可靠度進行了初步評估，得出了襯砌的相關位移與內力的均值和方差，並計算出了相應的襯砌結構可靠指標。
  2. First, this paper gives an introduction of some methods of unequal probability sampling, their estimators and variance estimators, including sampling with pps with replacement, methods of sampling without replacement suggested by brewer, durbin, sampford, des raj, murthy, rao - hartley - cochran. then, at the basis of rao and bayless ' s study, we consider that population can be splited two random subpopulations, which are respectively drawn from different infinite super - populations, and compare the stabilities of estimators of the methods that given above. we find that the minor difference between two super - populations has great effect on the efficiency of the estimators for the population with moderately large coefficient of variation ( c. v. )

    本文首先從理論上介紹了若干種不等概率抽樣方法，它們的估計量、估計量的方差及其估計，其中包括有放回ppz及pps抽樣，不放回不等概率抽樣中的brewer 、 durbin 、 sampford 、 desraj ， murthy 、 rao - hartley - cochran等人的方法；其次，在rao和bayless兩人就樣本單元數n = 2的情形對上述抽樣方法進行比較的基礎上，將總體隨機地分成兩個子總體，視每個子總體取自不同的線性超總體，在文中，我們利用計算機實現隨機分組，並通過畫圖比較各方法估計量的穩定性，結果表明，對變異系數c . v . （ x ）較大的總體而言，兩個超總體之間的微小差異將對估計量的穩定性產生很大的影響，從而說明rao和bayless的比較結果還不夠完善。
  3. On the loess plateau, water is the main limiting factors for vegetation growth. root distribution characters have special ecological meaning as it reflected the utilizations of trees to the environments. even - aged stands of robinia pseudoacacia on slope lands facing south and north were selected as sampling plots for root distribution investigation. investigatiing results showed that indicated that on all sites, root biomass decreased with depth, and the distribution depth of fine root was deeper than that of coarser root. the results of variance analysis indicated that there were great differences in root biomass among different diameter classes, and coarser root was the main sources of variance, and the root biomass, especially fine root ( < 3mm ) biomass on northern exposition sites was bigger than that on southern exposition sites. analysis of the vertical root distribution parameters, root extinction coefficient, indicated that the value of on northern exposition was more than 0. 982, while the value of on southern exposition was less than 0. 982, which indicated that the vertical root distribution depth of robinia pseudoacacia on southern exposition was deeper than that on southern exposition. and the distribution depth of fine roots ( < 1mm ) was deeper than that of thicker roots ( < 3mm ), which was in favor of the uptake of water and nutrients from deeper layers, helped the trees to adapt the arid environment, and promoted the growth of the upper parts of the tree

    在中國西北黃土高原地區，水分是樹木生長發育的主要限制因子.根系分佈特徵由於反映了樹木對環境條件的利用程度而具有更加特殊的生態意義.本研究選擇陽坡和陰坡不同立地上年齡一致的刺槐林調查了根系分佈特徵.根系垂直分佈特徵的調查結果表明，在所有立地上，根系生物量隨著深度的增加而降低，其中細根的分佈深度大於粗根的分佈深度.方差分析結果表明:不同立地上不同徑級根系的分佈特徵也有明顯的差別，粗根是差異存在的主要原因，陰坡立地上的根系生物量，特別是細根生物量大於陽坡立地上的.對根系消弱系數的分析結果表明，陰坡立地上的根系消弱系數大於0 . 982 ，而陽坡立地上的根系消弱系數小於0 . 982 ，說明陰坡立地上刺槐根系的生物量在深層土壤中的分佈相對量更大一些.其中細根的根系消弱系數大於粗根的，這種根系分佈特徵有利於根系對深層土壤水分養分的吸收利用，進而促進樹木地上部分的生長發育.圖3表3參15
  4. Abstract : on the loess plateau, water is the main limiting factors for vegetation growth. root distribution characters have special ecological meaning as it reflected the utilizations of trees to the environments. even - aged stands of robinia pseudoacacia on slope lands facing south and north were selected as sampling plots for root distribution investigation. investigatiing results showed that indicated that on all sites, root biomass decreased with depth, and the distribution depth of fine root was deeper than that of coarser root. the results of variance analysis indicated that there were great differences in root biomass among different diameter classes, and coarser root was the main sources of variance, and the root biomass, especially fine root ( < 3mm ) biomass on northern exposition sites was bigger than that on southern exposition sites. analysis of the vertical root distribution parameters, root extinction coefficient, indicated that the value of on northern exposition was more than 0. 982, while the value of on southern exposition was less than 0. 982, which indicated that the vertical root distribution depth of robinia pseudoacacia on southern exposition was deeper than that on southern exposition. and the distribution depth of fine roots ( < 1mm ) was deeper than that of thicker roots ( < 3mm ), which was in favor of the uptake of water and nutrients from deeper layers, helped the trees to adapt the arid environment, and promoted the growth of the upper parts of the tree

    文摘:在中國西北黃土高原地區，水分是樹木生長發育的主要限制因子.根系分佈特徵由於反映了樹木對環境條件的利用程度而具有更加特殊的生態意義.本研究選擇陽坡和陰坡不同立地上年齡一致的刺槐林調查了根系分佈特徵.根系垂直分佈特徵的調查結果表明，在所有立地上，根系生物量隨著深度的增加而降低，其中細根的分佈深度大於粗根的分佈深度.方差分析結果表明:不同立地上不同徑級根系的分佈特徵也有明顯的差別，粗根是差異存在的主要原因，陰坡立地上的根系生物量，特別是細根生物量大於陽坡立地上的.對根系消弱系數的分析結果表明，陰坡立地上的根系消弱系數大於0 . 982 ，而陽坡立地上的根系消弱系數小於0 . 982 ，說明陰坡立地上刺槐根系的生物量在深層土壤中的分佈相對量更大一些.其中細根的根系消弱系數大於粗根的，這種根系分佈特徵有利於根系對深層土壤水分養分的吸收利用，進而促進樹木地上部分的生長發育.圖3表3參15
  5. In chapter 1, the author first study the two - stage confidece intervals for the variance of a normal distribution, then work out the optimal sample size of the first stage by numerical computations and establish a proof for the non - existence of fixed - size sampling

    在第1章里，作者首先研究了正態總體方差的兩步置信區間，並用數值計算的方法給出了第一步的最優抽樣量，且證明了固定樣本抽樣的不存在性。
  6. The present methods for testing the large - scale corpus segmentation have the following faults : a. it is difficult to exactly estimating the variance of population ; b. the sampling quantity is too large to test the corpus segmentation. to solve the given problems, we put forward the testing method based on clustering, which sorts the sample of corpus into many group by clustering them

    語料庫分詞質量的評價問題是漢語語料庫的特有問題，已有的簡單隨機抽樣的方法，當語料庫規模變大時，無法精確估計分詞質量評價中語料庫樣本的總體方差，同時，為了保證檢驗的精度，傳統抽樣方法的檢驗費用太高。
  7. The following merits can gain by using the clustering method : a. the sampling quantity can be reduced by using the method to test the segmentation of the large - scale corpus ; b. the testing precision can be improved and the variance of population can be estimated more exactly

    與已有的簡單隨機抽樣方法相比，本文提出的方法在大規模語料庫分詞質量評價時，有如下優點； a通過聚類得到語料庫抽樣樣本分詞正確率的分層知識，進而在檢驗中運用分層抽樣帶來的增益減少檢驗的費用： b
  8. Determining the sample size is crucial for a survey sampling design, for which traditional approaches have to seek some information on population variance or survey costs, however, which may result in either sample size too small and real precision undre desired level, or sample size too large and waste of survey costs

    摘要樣本量的確定是抽樣設計中的關鍵問題，傳統方法利用總體方差和調查費用的有關信息來確定樣本量可能產生兩種結果，一種是樣本量過低，無法保證希望的估計精度要求；一種是樣本量過高，導致調查經費的浪費。
  9. Based on the port and waterway superintendence units, we study and screen the detailed method for the sample survey of whole industry waterway transportation volume, including selecting detailed sampling method, determining the appropriate sampling size, designing the calculation formula of all target estimators and their variance estimation

    包括選定具體的抽樣方法，確定合適的樣本量，給出需估計目標量的估計公式及估計量的精度公式，制定詳細的樣本調查規定和編制科學合理的樣本調查表等。
  10. Drawing out the standard of quality control means to combine the sampling and analysis procedures together and draws out the justified limit of the allowed variance

    其中質量控制標準的制定，是把采樣和分析測試過程綜合進行?慮，制定合理的允許誤差限度。
  11. High variance reduction and processing time saving due to systematic descriptive sampling could be expected

    用系統描述性抽樣代替蒙特卡羅的隨即抽樣過程，從而使得計算效率與降低方差都得到了明顯地改善。
  12. The analysis of how the training model influenced the students " thinking ability, creativity and study performance is done by using a few statistical methods including analysis of double samples " variance, supposition of double sampling, testing of significant difference

    運用雙樣本方差分析，雙樣本假設、差異顯著性檢驗等幾種統計方法，分析了六階段思維策略訓練的課堂操作模式對學生思維能力、創新意識、學習成績的影響。
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