Recognition of Short Time Periods through Seriation

1977 ◽  
Vol 42 (4) ◽  
pp. 628-629 ◽  
Author(s):  
Clement W. Meighan

One aspect of the recent article by Drennan (1976) merits some additional discussion. This has to do with the units of time that can be discriminated by seriation methods. One advance claimed for the new method proposed is that it allows for time placement within 25 years or so, stated as “ … finer than most traditional seriation.” In an article published 17 years ago, I showed this degree of time discrimination, with a much simpler graphical method of seriation.

2000 ◽  
Vol 199 (2) ◽  
pp. 179-185 ◽  
Author(s):  
M Strømme Mattsson ◽  
P Hedenus ◽  
G.A Niklasson ◽  
R Ek
Keyword(s):  

1957 ◽  
Vol 24 (1) ◽  
pp. 81-84
Author(s):  
E. G. Thomsen

Abstract A graphical method for the rapid construction of Hencky-Prandtl nets has been developed. The principle employed has been stated in a theorem. It is shown that the method may be used for nets on both the physical plane and on the velocity plane or hodograph. The use is illustrated by examples.


Author(s):  
Mark Stromp ◽  
Alexandra Farkas ◽  
Balázs Kretzer ◽  
Dénes Száz ◽  
András Barta ◽  
...  

Inspired by the pioneer work of the nineteenth century photographer, William Nicholson Jennings, we studied quantitatively how realistic painted lightnings are. In order to answer this question, we examined 100 paintings and 400 photographs of lightnings. We used our software package to process and evaluate the morphology of lightnings. Three morphological parameters of the main lightning branch were analysed: (i) number of branches N b , (ii) relative length r , and (iii) number of local maxima (peaks) N p of the turning angle distribution. We concluded: (i) Painted lightnings differ from real ones in N b and N p . (ii) The r -values of painted and real lightnings vary in the same range. (iii) 67 and 22% of the studied painted and real lightnings were non-bifurcating ( N b  = 1, meaning only the main branch), the maximum of N b of painted and real lightnings is 11 and 51, respectively, and painted bifurcating lightnings possess mostly 2–4 branches, while real lightnings have mostly 2–10 branches. To understand these findings, we performed two psychophysical experiments with 10 test persons, whose task was to guess N b on photographs of real lightnings which were flashed for short time periods Δ t  = 0.5, 0.75 and 1 s (characteristic to lightnings) on a monitor. We obtained that (i) test persons can estimate the number of lightning branches quite correctly if N b  ≤ 11. (ii) If N b  > 11, its value is strongly underestimated with exponentially increasing difference between the real and estimated numbers. (iii) The estimation is independent of the flashing period Δ t of lightning photos/pictures. (iv) The estimation is more accurate, if skeletonized lightning pictures are flashed, rather than real lightning photos. These findings explain why artists usually illustrate lightnings with branches not larger than 11.


Author(s):  
Kimberly A. With

Spatial patterns are ubiquitous in nature, and ecological systems exhibit patchiness (heterogeneity) across a range of spatial and temporal scales. Landscape ecology is explicitly concerned with understanding how scale affects the measurement of heterogeneity and the scale(s) at which spatial pattern is important for ecological phenomena. Patterns and processes measured at fine spatial scales and over short time periods are unlikely to behave similarly at broader scales and extended time periods. An understanding of pattern-process linkages, a major research focus in landscape ecology, thus requires an understanding of how patterns change with scale, spatially and temporally. The development of methods for extrapolating information across scales is necessary for predicting how landscapes will change over time as well as for ecological forecasting. This chapter explores how scaling issues affect ecological investigations, discusses problems in identifying the correct scale for research, and outlines when and how ecological data can be extrapolated.


2019 ◽  
Vol 25 (1) ◽  
pp. 85-90 ◽  
Author(s):  
M. Javad Poursharifi ◽  
Mohammad M. Mojtahedi ◽  
M. Saeed Abaee ◽  
Mohammad M. Hashemi

AbstractA method is developed for in situ generation of 1,3-dioxan-5-one derivatives 2. These compounds are simple precursors for accessing carbohydrate structures and previously had to be produced via stepwise procedures using excessive amounts of reagents. In the present work, three different derivatives of 2 were synthesized via the reaction of trialkoxyalkanes with dihydroxyacetone dimer 1 in the presence of acetic acid as the catalyst. In the same pot, derivatives of 2 were reacted with aromatic aldehydes and 30 mol% of pyrrolidine to obtain high yields of the respective bischalcones 3 within short time periods.


Sensors ◽  
2019 ◽  
Vol 19 (10) ◽  
pp. 2400 ◽  
Author(s):  
Wanjun Sheng ◽  
Xiangfu Wang ◽  
Yong Tao ◽  
Xiaohong Yan

We report a new method for detecting variable resistance during short time intervals by using an optical method. A novel variable-resistance sensor composed of up-conversion nanoparticles (NaYF4:Yb3+,Er3+) and reduced graphene oxide (RGO) is designed based on characteristics of a negative temperature coefficient (NTC) resistive element. The fluorescence intensity ratio (FIR) technology based on green and red emissions is used to detect variable resistance. Combining the Boltzmann distributing law with Steinhart–Hart equation, the FIR and relative sensitivity SR as a function of resistance can be defined. The maximum value of SR is 1.039 × 10−3/Ω. This work reports a new method for measuring variable resistance based on the experimental data from fluorescence spectrum.


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