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991.
In this paper, we describe two methods of discrimination based on MSE ratio and regression, respectively, and an algorithm of orthogonally stepwise discrimination. The method is not limited by the assumption that the sample covariance matrix is not ill-conditioned or singular, and by any assumption about the distribution of each population as well. So, it has wide range of application to various problems, particularly, to the problem of discrimination with both quantitative and qualitative variables. After variables are selected in the procedure of stepwise discrimination, they need not be rejected. Several examples have been calculated by using the method, and the results are quite satisfying. 相似文献
993.
A survey for emission line stars was carried out in 1980 with the Schmidt telescope of Konkoly Observatory in the region of IC 1396 (Kun, 1986a, hereafter referred to as Paper I). This work was aimed at a preliminary mapping of the probable medium mass members of the association Cepheus OB 2. The stars of the region have been followed since then with the same telescope in order to obtain a more complete view on the stellar content of this giant star-forming region. The common variability of the H emission strength makes the sense of repeating such surveys. The new survey resulted in the discovery of 65 further emission stars. Equatorial coordinates and finding charts are given for them.PhotographicBVRI photometry was carried out for all known emission stars of the field. The colourmagnitude and two-colour diagrams derived from theB, V, R, andI magnitudes show that these stars are probably F-G-type (1.5M
<M<3M
), partly pre-Main-Sequence members of Cep OB 2, whereas a few of them may be distant red giants.The youngest objects of the region can be found among the IRAS point sources. Their properties are discussed on the basis of IRAS data alone. 相似文献
994.
Two different goals in fitting straight lines to data are to estimate a true linear relation (physical law) and to predict values of the dependent variable with the smallest possible error. Regarding the first goal, a Monte Carlo study indicated that the structural-analysis (SA) method of fitting straight lines to data is superior to the ordinary least-squares (OLS) method for estimating true straight-line relations. Number of data points, slope and intercept of the true relation, and variances of the errors associated with the independent (X) and dependent (Y) variables influence the degree of agreement. For example, differences between the two line-fitting methods decrease as error in X becomes small relative to error in Y. Regarding the second goal—predicting the dependent variable—OLS is better than SA. Again, the difference diminishes as X takes on less error relative to Y. With respect to estimation of slope and intercept and prediction of Y, agreement between Monte Carlo results and large-sample theory was very good for sample sizes of 100, and fair to good for sample sizes of 20. The procedures and error measures are illustrated with two geologic examples. 相似文献
995.
Kriging with imprecise (fuzzy) variograms. I: Theory 总被引:2,自引:0,他引:2
Imprecise variogram parameters are modeled with fuzzy set theory. The fit of a variogram model to experimental variograms is often subjective. The accuracy of the fit is modeled with imprecise variogram parameters. Measurement data often are insufficient to create good experimental variograms. In this case, prior knowledge and experience can contribute to determination of the variogram model parameters. A methodology for kriging with imprecise variogram parameters is developed. Both kriged values and estimation variances are calculated as fuzzy numbers and characterized by their membership functions. Besides estimation variance, the membership functions are used to create another uncertainty measure. This measure depends on both homogeneity and configuration of the data. 相似文献
996.
997.
998.
Slitless spectrograms obtained during the eclipse of 10 June 1972 have been analyzed to determine the height distribution of the D3 He line intensity.For undisturbed regions the maximum of D3 line intensity is confirmed to exist at about 1700km above the limb. Besides the above mentioned maximum, in plages a considerable intensity may be observed at low heights (h < 1000 km).An analysis of these observations for h > 1000 km has been carried out within the low temperature mechanism of triplet helium emission taking into account the helium ionization by XUV radiation. The density dependence of the 23
S level population at different XUV flux values has been calculated. Our observations give N
e 2 × 1010 cm–3 in the chromosphere at h = 2000 km. The probable coincidence of the H and He emission small filaments in the middle chromosphere is discussed. 相似文献
999.
云南省禄劝县开发方向的初步研究 总被引:1,自引:0,他引:1
云南省禄劝县隶属昆明市辖区,是一个国家级扶贫开发重点县之一.境内河流众多,水资源丰富,但地表切割强烈,山高谷深,坝地仅占总面积的1.6%,复杂的地貌条件严重制约了县域经济的发展.从禄劝县资源优势出发,变劣势为优势,提出发展生态种植业,生态养殖业和生态林果业的持续农业发展方向,使禄劝县发展成昆明市的菜篮子基地,为农民脱贫致富,增加收入提出了一条切实可行的路子. 相似文献
1000.
库姆塔格沙漠"羽毛状沙丘"形态的示量特征 总被引:10,自引:2,他引:10
通过卫星照片判读和实地观测,库姆塔格沙漠的“羽毛状沙丘”由两种风沙地貌构成:东北-西南走向的新月形“沙垄”为“羽轴”;垄间分布的波状微起伏的“大沙波”为“羽枝”,“大沙波”与沙垄的夹角为75°~103°。二者组合成类似“羽毛”的风沙地貌。新月形“沙垄”由单个新月形沙丘的前一沙丘的迎风坡与后一沙丘东翼相连构成“沙垄”。组成“沙垄”的新月形沙丘的两翼平均长37.5m,翼间距30~66m,沙丘高3~19m;在所观测区域内,沙丘沙的分选性由南向北变差。新月形“沙垄”长为3~22km,垄间距为1~3km,其问分布浅色和暗色相间的波状微地貌,暗色部分平均宽24.3m,浅色部分的平均宽11.6m。暗色部分表层沙粒的粒径有60%在1.00~0.25mm之间,以暗色矿物为主,而浅色部分表层沙粒的粒径的90%在1.00~0.25mm之间,分选性相对暗色部分较好,以石英等浅色矿物为主。暗色和浅色微地貌成对出现,相对高差约7cm。这种波状微地貌在库姆塔格沙漠中北部重复出现,类似于风沙地貌分类的沙波,暂称其为“大沙波”。 相似文献