scholarly journals Antipersistent dynamics in short time scale variability of self-potential signals

2000 ◽  
Vol 43 (2) ◽  
Author(s):  
V. Cuomo ◽  
M. Lanfredi ◽  
V. Lapenna ◽  
M. Macchiato ◽  
M. Ragosta ◽  
...  
Keyword(s):  
Time Scale ◽  
Order Structure ◽  
Short Time Scale ◽  
Spatial And Temporal Variability ◽  
Scale Invariant ◽  
Geophysical Monitoring ◽  
Scale Properties ◽  
Short Time ◽  
Self Potential

Time scale properties of self-potential signals are investigated through the analysis of the second order structure function (variogram), a powerful tool to investigate the spatial and temporal variability of observational data. In this work we analyse two sequences of self-potential values measured by means of a geophysical monitoring array located in a seismically active area of Southern Italy. The range of scales investigated goes from a few minutes to several days. It is shown that signal fluctuations are characterised by two time scale ranges in which self-potential variability appears to follow slightly different dynamical behaviours. Results point to the presence of fractal, non stationary features expressing a long term correlation with scaling coefficients which are the clue of stabilising mechanisms. In the scale ranges in which the series show scale invariant behaviour, self-potentials evolve like fractional Brownian motions with anticorrelated increments typical of processes regulated by negative feedback mechanisms (antipersistence). On scales below about 6 h the strength of such an antipersistence appears to be slightly greater than that observed on larger time scales where the fluctuations are less efficiently stabilised.

On Failure Mechanisms in Flip Chip Assembly—Part 2: Optimal Underfill and Interconnecting Materials

2008 ◽  
Vol 130 (2) ◽  
Author(s):  
Yoonchan Oh ◽  
C. Steve Suh ◽  
Hung-Jue Sue
Keyword(s):  
Time Scale ◽  
Flip Chip ◽  
Thermal Stresses ◽  
Failure Modes ◽  
Scale Effects ◽  
Short Time Scale ◽  
Long Time ◽  
Solder Joint Fatigue ◽  
Scale Properties ◽  
Short Time

The physics explored in this investigation enables short-time scale dynamic phenomenon to be correlated with package failure modes such as solder ball cracking and interlayer debond. It is found that although epoxy-based underfills with nanofillers are shown to be effective in alleviating thermal stresses and improving solder joint fatigue performance in thermal cycling tests of long-time scale, underfill material viscoelasticity is ineffective in attenuating short-time scale propagating shock waves. In addition, the inclusion of Cu interconnecting layers in flip chip area arrays is found to perform significantly better than Al layers in suppressing short-time scale effects. Results reported herein suggest that, if improved flip chip reliability is to be achieved, the compositions of all packaging constituent materials need be formulated to have well-defined short-time scale and long-time scale properties. Chip level circuit design layout also needs be optimized to either discourage or negate short-time wave propagation. The knowledge base established is generally applicable to high performance package configurations of small footprint and high clock speed. The approach along with the numerical procedures developed for the investigation can be a practical tool for realizing better device reliability and thus high manufacturing yield.

AI and HCI: Two Fields Divided by a Common Focus

AI Magazine ◽  
2009 ◽  
Vol 30 (4) ◽  
pp. 48 ◽  
Author(s):  
Jonathan Grudin
Keyword(s):  
Time Scale ◽  
Short Time Scale ◽  
Intelligent Behavior ◽  
History Of ◽  
Short Time ◽  
Competition For Resources

Although AI and HCI explore computing and intelligent behavior and the fields have seen some cross-over, until recently there was not very much. This article outlines a history of the fields that identifies some of the forces that kept the fields at arm’s length. AI was generally marked by a very ambitious, long-term vision requiring expensive systems, although the term was rarely envisioned as being as long as it proved to be, whereas HCI focused more on innovation and improvement of widely-used hardware within a short time-scale. These differences led to different priorities, methods, and assessment approaches.  A consequence was competition for resources, with HCI flourishing in AI winters and moving more slowly when AI was in favor. The situation today is much more promising, in part because of platform convergence: AI can be exploited on widely-used systems.

Short.Term Reactivity Change: Xenon Effects

2021 ◽  
pp. 67-79
Author(s):  
Wei Shen ◽  
Benjamin Rouben
Keyword(s):  
Fission Product ◽  
Time Scale ◽  
Fission Products ◽  
Fuel Burnup ◽  
Short Time Scale ◽  
Neutron Absorption ◽  
Short Time ◽  
Reactivity Change

Most fission products absorb neutrons to some extent and they accumulate slowly as the fuel burnup increases, hence decrease the long-term reactivity. The neutron-absorbing fission-product xenon-135 has particular operational importance. Its concentrations can change quickly in a power maneuvre, producing major changes in neutron absorption on a relatively short-time scale (minutes).

Linguistic diversification as a long-term effect of asymmetric priming

2018 ◽  
Vol 8 (2) ◽  
pp. 253-296
Author(s):  
Andreas Baumann ◽  
Lotte Sommerer
Keyword(s):  
Mathematical Model ◽  
Population Dynamics ◽  
Time Scale ◽  
Language Change ◽  
Term Effect ◽  
Short Time Scale ◽  
Cognitive Mechanism ◽  
Long Term Effect ◽  
Short Time

Abstract This paper tries to narrow the gap between diachronic linguistics and research on population dynamics by presenting a mathematical model corroborating the notion that the cognitive mechanism of asymmetric priming can account for observable tendencies in language change. The asymmetric-priming hypothesis asserts that items with more substance are more likely to prime items with less substance than the reverse. Although these effects operate on a very short time scale (e.g. within an utterance) it has been argued that their long-term effect might be reductionist, unidirectional processes in language change. In this paper, we study a mathematical model of the interaction of linguistic items that differ in their formal substance, showing that, in addition to reductionist effects, asymmetric priming also results in diversification and stable coexistence of two formally related variants. The model will be applied to phenomena in the sublexical as well as the lexical domain.

An Alternative Test Using Algal Cultures for Testing Chemicals for Toxicity

1993 ◽  
Vol 21 (2) ◽  
pp. 196-201
Author(s):  
Søren Achim Nielsen ◽  
Thomas Hougaard
Keyword(s):  
Size Distribution ◽  
Mitotic Activity ◽  
Time Scale ◽  
Test System ◽  
Short Time Scale ◽  
Toxic Substances ◽  
Alternative Test ◽  
Short Time ◽  
Algal Cultures ◽  
Test Cultures

An alternative test is presented, in which algal cultures are used for testing toxic substances. This test system is based on variations in the size distribution of cells in test cultures as a measurement of growth. Thus, inhibition of mitotic activity is used as a measurement for toxic effects. The test can be performed on a short time-scale and is very sensitive to even weak toxic doses.

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