Uncertain max-autoregressive model with imprecise observations

2021 ◽  
pp. 1-8
Author(s):  
Han Tang ◽  
Dalin
Keyword(s):  
Time Series ◽  
Nonlinear Model ◽  
Short Term ◽  
Unknown Parameters ◽  
Underlying Process ◽  
Short Term Change ◽  
Term Change ◽  
Uncertain Time ◽  
Imprecise Observations ◽  
Theoretical Results

Uncertain time series analysis has been developed for studying the imprecise observations. In this paper, we propose a nonlinear model called uncertain max-autoregressive (UMAR) model. The unknown parameters in model are estimated by the least squares estimation. Then the residual analysis is presented. In many cases, there are some outliers in the time series due to short-term change in the underlying process. The UMAR model offers an alternative for detecting outliers in the imprecise observations. Based on the previous theoretical results, the UMAR model is used to forecast the future. Finally, an example suggests that the new proposed time series model works well compared to the uncertain autoregressive (UAR) model.

scholarly journals Short-Term Change Detection in Wetlands Using Sentinel-1 Time Series

2016 ◽  
Vol 8 (10) ◽  
pp. 795 ◽  
Author(s):  
Javier Muro ◽  
Morton Canty ◽  
Knut Conradsen ◽  
Christian Hüttich ◽  
Allan Nielsen ◽  
...  
Keyword(s):  
Time Series ◽  
Change Detection ◽  
Short Term ◽  
Short Term Change ◽  
Term Change

scholarly journals The Relationship between Body Mass Index and Mammographic Density during a Premenopausal Weight Loss Intervention Study

Cancers ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 3245
Author(s):  
Emma C. Atakpa ◽  
Adam R. Brentnall ◽  
Susan Astley ◽  
Jack Cuzick ◽  
D. Gareth Evans ◽  
...  
Keyword(s):  
Body Mass Index ◽  
Weight Loss ◽  
Body Mass ◽  
Breast Density ◽  
Small Sample ◽  
Weight Loss Intervention ◽  
Short Term ◽  
Dense Area ◽  
Short Term Change ◽  
Term Change

We evaluated the association between short-term change in body mass index (BMI) and breast density during a 1 year weight-loss intervention (Manchester, UK). We included 65 premenopausal women (35–45 years, ≥7 kg adult weight gain, family history of breast cancer). BMI and breast density (semi-automated area-based, automated volume-based) were measured at baseline, 1 year, and 2 years after study entry (1 year post intervention). Cross-sectional (between-women) and short-term change (within-women) associations between BMI and breast density were measured using repeated-measures correlation coefficients and multivariable linear mixed models. BMI was positively correlated with dense volume between-women (r = 0.41, 95%CI: 0.17, 0.61), but less so within-women (r = 0.08, 95%CI: −0.16, 0.28). There was little association with dense area (between-women r = −0.12, 95%CI: −0.38, 0.16; within-women r = 0.01, 95%CI: −0.24, 0.25). BMI and breast fat were positively correlated (volume: between r = 0.77, 95%CI: 0.69, 0.84, within r = 0.58, 95%CI: 0.36, 0.75; area: between r = 0.74, 95%CI: 0.63, 0.82, within r = 0.45, 95%CI: 0.23, 0.63). Multivariable models reported similar associations. Exploratory analysis suggested associations between BMI gain from 20 years and density measures (standard deviation change per +5 kg/m2 BMI: dense area: +0.61 (95%CI: 0.12, 1.09); fat volume: −0.31 (95%CI: −0.62, 0.00)). Short-term BMI change is likely to be positively associated with breast fat, but we found little association with dense tissue, although power was limited by small sample size.

Short-Term Change in a Population of the Meat Ant Iridomyrmex Purpureus (Hymenoptera: Formicidae).

1975 ◽  
Vol 23 (4) ◽  
pp. 511 ◽  
Author(s):  
PJM Greenslade
Keyword(s):  
Seasonal Variation ◽  
Colony Size ◽  
Critical Factor ◽  
Nest Entrance ◽  
Short Term ◽  
Growth And Survival ◽  
Short Term Change ◽  
Term Change ◽  
Rates Of Growth ◽  
Size And Structure

A population of the mound-building meat ant, Iridomyrmex purpureus s. s., was studied from 1971 to 1974 near the cool, wet end of its South Australian range. Seasonal variation in the numbers of nest mounds, and in number of nest entrance holes used by the population, indicate that it is under climatic stress in winter and summer. It is also subject to human interference and many mounds have been damaged; the fate of such colonies suggests that the mounds affect nest temperatures and are important in reducing winter stress. Comparison of parts of the population from areas differing in aspect and drainage shows that colony size and structure are controlled by rates of growth and survival of nests, depending largely on summer and winter stress respectively. The latter appears to be the critical factor in this population.

scholarly journals Short-term change in fish assemblages after the passage of a typhoon in a temperate, coastal bay

2021 ◽  
Vol 51 (2) ◽  
pp. 175-183
Author(s):  
Mitsuharu Yagi
Keyword(s):  
Fish Assemblages ◽  
Japanese Anchovy ◽  
Short Term ◽  
Faunal Change ◽  
Short Term Change ◽  
Term Change ◽  
Fish Samples ◽  
Before And After ◽  
Coastal Bay ◽  
Tachibana Bay

To study the effects of a typhoon on a temperate, coastal bay community, the species composition, catch amount, and diversity of epipelagic fish assemblages were investigated. Fish samples were taken from catches of a purse seine fishery in Tachibana Bay, Japan between May and July 2011, covering before and after the passage of a typhoon in the area. Although major changes in total catch amount were not observed before and after the passage of the typhoon, the abundance of the Japanese anchovy, Engraulis japonicus Temminck et Schlegel, 1846, markedly decreased and bycatch of species increased, accompanied by increasing levels of diversity of the fish assemblage. Multivariate analysis showed that community differences before and after the passage were quantitative rather than qualitative. Comparisons in total length frequencies between the two periods indicated that specimens of the species compared were bigger in size for Trachurus japonicus (Temminck et Schlegel, 1844) and smaller for E. japonicus in the “after” period. These results suggest that the passage of the typhoon triggered not only interspecific faunal change but also intraspecific recruitment shifts in and around the bay.

scholarly journals 190 PCBS, PCDDS AND PCDFS IN HUMAN MILK DOES A SHORT TERM-CHANGE IN MATERNAL DIET INFLUENCE THEIR CONCENTRATION?

1994 ◽  
Vol 36 (1) ◽  
pp. 34A-34A
Author(s):  
Beate Pietschnig ◽  
Karin Wiberg ◽  
Ferdinand Haschke ◽  
Christopher Rappe ◽  
Ernst Schuster
Keyword(s):  
Human Milk ◽  
Maternal Diet ◽  
Short Term ◽  
Short Term Change ◽  
Term Change

Assessing Short-term Change in Advanced Oral Proficiency

1995 ◽  
Vol 109-110 ◽  
pp. 75-109 ◽  
Author(s):  
Paul Lennon
Keyword(s):  
Native Speaker ◽  
Mother Tongue ◽  
Oral Proficiency ◽  
Teacher Assessment ◽  
Short Term ◽  
Advanced Learners ◽  
Short Term Change ◽  
Term Change ◽  
Efl Teachers ◽  
Picture Story

Abstract This paper presents four case studies to demonstrate developments in oral proficiency made by advanced learners of English during two months in England. The data base consists of picture story oral narratives. Performance shortly after arrival in Britain is compared with that at the end of the two months. Assessment was by: subjective reactions of a panel of experienced native-speaker EFL teachers quantitative analysis of transcriptions of recordings. An attempt is made to apply VORSTER’s (1980) components of proficiency developed for use with children mother tongue speakers. The main findings were as follows: There was considerable dissension among teachers, so that the reliability of subjective teacher assessment in such cases must be seriously questioned. Results on the objective quantitative measures were very chequered, suggesting that the variables chosen did not, in many cases, function well to identify developments over so short a period. Nevertheless, there were clear trends towards improvements in productivity and modality (co-verbs). There were signs of individual differences among subjects in route of development.

Sign in / Sign up

Export Citation Format

Share Document