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1.
郑景云 《云南大学学报(社会科学版)》2021,20(4):35-39
寨堡是我国古代重要的军事防御性聚落,其修筑的时间、空间皆与区域的战争形势有着较大关系。清代四川省由于多次大规模战乱,迫使乡民修筑了数以千计的寨堡。寨堡的命名主要可分为因自然地理条件和因人文社会因素两大类,前者包括地形、水文、土石、植物等,后者包括姓氏、寺观、神祇、嘉名、人物、神话、形象、纪事等。寨名包含了丰富的文化内涵,体现出了寨堡的选址、用材、作用、历史、精神等内容。 相似文献
2.
舟山灯塔历史概述 总被引:1,自引:0,他引:1
邓进平 《浙江海洋学院学报(人文科学版)》2015,(3)
灯塔一般位于海岸、港口或河道,用以指引船只的航行方向。灯塔大都类似塔的形状,透过塔顶的透镜系统,将光芒射向海面或河面照明。舟山地处我国大陆海岸线中部,长江口南侧,杭州湾外缘东海洋面上,自古有“江浙之门户,四明之藩篱”之称,历史上就为中国重要的海上贸易通道。为保障海上航行安全,舟山很早就设立导航设施,到清晚期,随着航线的日益繁忙以及导航技术的发展,舟山设立了众多的近代灯塔,这些灯塔大多保留完整,其数量之多,密度之高,在全国首屈一指。 相似文献
3.
A NOTE ON EVANESCENT PROCESSES 总被引:1,自引:0,他引:1
This note examines the connection between μ-invariant measures for the transition function of a continuous-time Markov chain and those of its q-matrix, Q. The major result establishes a necessary and aufficient condition for a convergent μ-invariant measure for Q to be μ-inhant for the minimal transition function, P, under the assumption that P is honest. This corrects Theorem 6 of Vere-Jones (1969) and the first part of Corollary 1 of Pollett (1986), both of which assert that the above conclusion holds in the absence of this condition. The error was pointed out by E.A. van Doom (1991) and the counterexample which be presented provides the basis for the present arguments. In determining where the error occurred in the original proof, we are able to identify a simple sufficient condition for μ-invariance. 相似文献
4.
Computing maximum likelihood estimates from type II doubly censored exponential data 总被引:1,自引:0,他引:1
Arturo J. fernández José I. Bravo Íñigo De Fuentes 《Statistical Methods and Applications》2002,11(2):187-200
It is well-known that, under Type II double censoring, the maximum likelihood (ML) estimators of the location and scale parameters, θ and δ, of a twoparameter exponential distribution are linear functions
of the order statistics. In contrast, when θ is known, theML estimator of δ does not admit a closed form expression. It is shown, however, that theML estimator of the scale parameter exists and is unique. Moreover, it has good large-sample properties. In addition, sharp
lower and upper bounds for this estimator are provided, which can serve as starting points for iterative interpolation methods
such as regula falsi. Explicit expressions for the expected Fisher information and Cramér-Rao lower bound are also derived.
In the Bayesian context, assuming an inverted gamma prior on δ, the uniqueness, boundedness and asymptotics of the highest
posterior density estimator of δ can be deduced in a similar way. Finally, an illustrative example is included. 相似文献
5.
Barry C. Arnold Enrique Castillo José María Sarabia 《Journal of statistical planning and inference》2008
The paper deals with the problem of using contours as the basis for defining probability distributions. First, the most general probability densities with given contours are obtained and the particular cases of circular and elliptical contours are dealt with. It is shown that the so-called elliptically contoured distributions do not include all possible cases. Next, the case of contours defined by polar coordinates is analyzed including its simulation and parameter estimation. Finally, the case of cumulative distribution functions with given contours is discussed. Several examples are used for illustrative purposes. 相似文献
6.
Children may be more susceptible to toxicity from some environmental chemicals than adults. This susceptibility may occur during narrow age periods (windows), which can last from days to years depending on the toxicant. Breathing rates specific to narrow age periods are useful to assess inhalation dose during suspected windows of susceptibility. Because existing breathing rates used in risk assessment are typically for broad age ranges or are based on data not representative of the population, we derived daily breathing rates for narrow age ranges of children designed to be more representative of the current U.S. children's population. These rates were derived using the metabolic conversion method of Layton (1993) and energy intake data adjusted to represent the U.S. population from a relatively recent dietary survey (CSFII 1994–1996, 1998). We calculated conversion factors more specific to children than those previously used. Both nonnormalized (L/day) and normalized (L/kg-day) breathing rates were derived and found comparable to rates derived using energy estimates that are accurate for the individuals sampled but not representative of the population. Estimates of breathing rate variability within a population can be used with stochastic techniques to characterize the range of risk in the population from inhalation exposures. For each age and age-gender group, we present the mean, standard error of the mean, percentiles (50th, 90th, and 95th), geometric mean, standard deviation, 95th percentile, and best-fit parametric models of the breathing rate distributions. The standard errors characterize uncertainty in the parameter estimate, while the percentiles describe the combined interindividual and intra-individual variability of the sampled population. These breathing rates can be used for risk assessment of subchronic and chronic inhalation exposures of narrow age groups of children. 相似文献
7.
Distributions generated by perturbation of symmetry with emphasis on a multivariate skew t-distribution 总被引:1,自引:0,他引:1
Adelchi Azzalini Antonella Capitanio 《Journal of the Royal Statistical Society. Series B, Statistical methodology》2003,65(2):367-389
Summary . A fairly general procedure is studied to perturb a multivariate density satisfying a weak form of multivariate symmetry, and to generate a whole set of non-symmetric densities. The approach is sufficiently general to encompass some recent proposals in the literature, variously related to the skew normal distribution. The special case of skew elliptical densities is examined in detail, establishing connections with existing similar work. The final part of the paper specializes further to a form of multivariate skew t -density. Likelihood inference for this distribution is examined, and it is illustrated with numerical examples. 相似文献
8.
The paper evaluates the accuracy of Burr approximations of critical values and p-values for test a of autocorrelation and heteroscedasticity in the linear regression model. 相似文献
9.
The robustness of Mauchly's sphericity test criterion when sampling from a mixture of two multivariate normal distributions is studied. The distribution of the sphericity test criterion when the sample covariance matrix has a non-central Wishart density of rank one is derived in terms of Meijer's G-functions; its distribution under the mixture model is then deduced. The robustness is studied by computing actual significance levels of the test under the mixture model using the critical values under the usual normal model. 相似文献
10.