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71.
加载减速法(LugDown)测量被测车辆处于100%、90%和80%VelMaxHP三个速度工况下的排气光吸收系数(k)和100%VelMaxHP速度工况下的最大轮边功率值(MaxHP),数据内涵增强,统计分析较为复杂。为解决此问题,本文根据LugDown法排气控制指标与测量数据特点,提出了排放最大值均值和功率比值统计分析方法,并将其用于广州市柴油车LugDown法排气检测数据的分析,结果令人满意。  相似文献   
72.
ABSTRACT: Annual maximum daily rainfall data from nine stations throughout the southern slopes of the Eastern Italian Alps with record length of 67–68 years have been analyzed with the aim of verifying if their internal structure justifies the assumption of independence and identical distribution, or the “White noise hypothesis.” The approach is to consider the hypothesis H0 of white noise as the intersection of several sub-hypotheses, each concerning one of the characteristics of a white noise process. To this end the nine series were subjected to various statistical tests regarding randomness, independence, change-points, and predictability. The results are examined first individually and then globally. They indicate that in eight of the nine considered time series the “white noise hypothesis” was rejected.  相似文献   
73.
A temporal record of environmental conditions is often contained within accretionary biological tissue. These records can provide knowledge of the environmental conditions that existed at the time the tissue was formed. In this study, we look at trace element concentrations and isotopic ratios of carbon and nitrogen as contained in baleen from bowhead whales in the eastern and western Arctic Ocean. Time series techniques, including maximum likelihood method and likelihood ratio tests, are applied to analysis of data and inference about their mean structures.  相似文献   
74.
溢油指示物(指标)的HPLC模糊最大矩阵元研究   总被引:8,自引:5,他引:8  
为了探讨HPLC模糊最大矩阵元作溢油指示物的可行性,用HPLC-FLD对15种常见油品和2种油品的海上不同风化时间的油样以及7种室外风化油样进行了分析,选取油样色谱指纹作为数据处理信息点,计算出模糊最大矩阵元λi。  相似文献   
75.
The purpose of this paper is to develop a set of associated statistical tests for spatial clustering. In particular, a set of three associated tests will be developed; these will correspond to the three types of tests set out by Besag and Newell (general tests, focused tests, and tests for the detection of clustering). The associated tests draw primarily, though not exclusively, upon existing tests and results. The principal contributions are based upon the score statistic for focused tests, which has been an important approach to testing for clustering around environmental hazards. The first contribution consists of the formulation of a global statistic for general tests that corresponds to focused score statistics, along with an assessment of the distribution of the statistic under the null hypothesis of no raised incidence. The local score statistics used for focused tests will have the property of summing to the global statistic used for the corresponding general test. Attention is also given to the maximum local score statistic for the “test for the detection of clustering”. The critical values of this statistic which are required for testing the null hypothesis are described. Application of the methods is made to leukemia data for central New York State.  相似文献   
76.
Developmental toxicity studies are widely used to investigate the potential risk of environmental hazards. In dose–response experiments, subjects are randomly allocated to groups receiving various dose levels. Tests for trend are then often applied to assess possible dose effects. Recent techniques for risk assessment in this area are based on fitting dose–response models. The complexity of such studies implies a number of non-trivial challenges for model development and the construction of dose-related trend tests, including the hierarchical structure of the data, litter effects inducing extra variation, the functional form of the dose–response curve, the adverse event at dam or at fetus level, the inference paradigm, etc. The purpose of this paper is to propose a Bayesian trend test based on a non-linear power model for the dose effect and using an appropriate model for clustered binary data. Our work is motivated by the analysis of developmental toxicity studies, in which the offspring of exposed and control rodents are examined for defects. Simulations show the performance of the method over a number of samples generated under typical experimental conditions.  相似文献   
77.
We investigate several methods commonly used to obtain a benchmark dose and show that those based on full likelihood or profile likelihood methods might have severe shortcomings. We propose two new profile likelihood-based approaches which overcome these problems. Another contribution is the extension of the benchmark dose determination to non full likelihood models, such as quasi-likelihood, generalized estimating equations, which are widely used in settings such as developmental toxicity where clustered data are encountered. This widening of the scope of application is possible by the use of (robust) score statistics. Benchmark dose methods are applied to a data set from a developmental toxicity study.  相似文献   
78.
以活性炭阳极双室生物燃料电池为基础,使用葡萄糖(COD为2000mg·L-1)作为底物,比较了铁氰化钾、过氧化氢、重铬酸钾和高锰酸钾分别作为生物燃料电池阴极电子受体时电池的开路电压和功率输出.结果表明,铁氰化钾、过氧化氢和重铬酸钾对应的开路电位分别为0.72V、0.33V和1.13V,均低于高锰酸钾的1.4lV.铁氰化钾和重铬酸钾对应的最大功率密度分别为4788mW·m-3和10951m W·m-3,相比之下高锰酸钾对应的最大功率达到了21912 mW·m-3.除过氧化氢外,3种氧化剂对应的电池内阻没有区别,均在2200Ω左右.当高锰酸钾浓度为200mg·L-1、pH为2.0时,开路电位高达1.44V,阴极电位达到1.38V,pH对电池电压输出的影响比高锰酸钾浓度更为显著.将高锰酸钾用于生物燃料电池从有机废水中发电不但可以极大提高系统的功率输出,还具有十分显著的经济和环境效益.  相似文献   
79.
This study investigates the safe carrying load limit in relation to gender of workers in the sugar industry. A total of 632 workers (male and female) were interviewed following a physiological and psycho-physiological methodology. All of these workers were in the age groups of 21–30, 31–40 and ≥41 years. In this study, for the physiological methodology, both field and laboratory data were collected, which included heart rate, heart rate variability, energy expenditure and maximum rate of oxygen consumption. Information regarding hemoglobin content, weight, age, lean body weight, etc., was recorded to know the physical health of the workers. In the psycho-physiological evaluation, load-carrying limits were determined by the psychophysical rating of the load by workers from the selected age groups. By considering the physiological stresses and psycho-physiological evaluation, the safe carrying load limit was determined in head and back mode for male and female workers as per their age groups.  相似文献   
80.
目的对不同环境条件试验下的数据进行融合。方法针对应用最为普遍的威布尔分布类型的环境折合因子进行研究,给出威布尔分布环境折合因子的定义,根据极大似然估计法对威布尔分布环境折合因子进行计算。结果得出了相关环境折合因子的计算结果,在此基础上给出了应用环境折合因子进行数据融合的方法和步骤。结论应用威布尔分布环境折合因子可以合理的对不同环境下试验数据进行融合,达到扩大试验样本的目的。  相似文献   
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