Contributions of visible persistence and perceptual set to the flash-lag effect: Focusing on flash onset abolishes the illusion

Horizontal loads such as earthquake and wind are considered dominant loads for the design of tall buildings. One of the most efficient structural systems in this regard is the tube structural system. Even though such systems have a high resistance when it comes to horizontal loads, the shear lag effect that is characterized by an incomplete and uneven activation of vertical elements may cause a series of problems such as the deformation of internal panels and secondary structural elements, which cumulatively grow with the height of the building. In this paper, the shear lag effect in a typical tube structure will be observed and analyzed on a series of different numerical models. A parametric analysis will be conducted with a great number of variations in the structural elements and building layout, for the purpose of giving recommendations for an optimal design of a tube structural system.

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Shear lag effect on stress concentration in simply-supported stiffened box girder

Journal of Constructional Steel Research ◽

10.1016/j.jcsr.2021.106715 ◽

2021 ◽

Vol 183 ◽

pp. 106715

Author(s):

Eiki Yamaguchi ◽

Naoto Kittaka ◽

Buchit Maho ◽

Piti Sukontasukkul

Keyword(s):

Stress Concentration ◽

Shear Lag ◽

Shear Lag Effect ◽

Box Girder ◽

Simply Supported ◽

Lag Effect

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A Weighted-Time-Lag Method to Detect Lag Vegetation Response to Climate Variation: A Case Study in Loess Plateau, China, 1982–2013

Remote Sensing ◽

10.3390/rs13050923 ◽

2021 ◽

Vol 13 (5) ◽

pp. 923

Author(s):

Qianqian Sun ◽

Chao Liu ◽

Tianyang Chen ◽

Anbing Zhang

Keyword(s):

Climate Change ◽

Loess Plateau ◽

Time Lag ◽

New Method ◽

Climate Factors ◽

The Loess Plateau ◽

Climate Conditions ◽

Vegetation Growth ◽

Lag Effect

Vegetation fluctuation is sensitive to climate change, and this response exhibits a time lag. Traditionally, scholars estimated this lag effect by considering the immediate prior lag (e.g., where vegetation in the current month is impacted by the climate in a certain prior month) or the lag accumulation (e.g., where vegetation in the current month is impacted by the last several months). The essence of these two methods is that vegetation growth is impacted by climate conditions in the prior period or several consecutive previous periods, which fails to consider the different impacts coming from each of those prior periods. Therefore, this study proposed a new approach, the weighted time-lag method, in detecting the lag effect of climate conditions coming from different prior periods. Essentially, the new method is a generalized extension of the lag-accumulation method. However, the new method detects how many prior periods need to be considered and, most importantly, the differentiated climate impact on vegetation growth in each of the determined prior periods. We tested the performance of the new method in the Loess Plateau by comparing various lag detection methods by using the linear model between the climate factors and the normalized difference vegetation index (NDVI). The case study confirmed four main findings: (1) the response of vegetation growth exhibits time lag to both precipitation and temperature; (2) there are apparent differences in the time lag effect detected by various methods, but the weighted time-lag method produced the highest determination coefficient (R2) in the linear model and provided the most specific lag pattern over the determined prior periods; (3) the vegetation growth is most sensitive to climate factors in the current month and the last month in the Loess Plateau but reflects a varied of responses to other prior months; and (4) the impact of temperature on vegetation growth is higher than that of precipitation. The new method provides a much more precise detection of the lag effect of climate change on vegetation growth and makes a smart decision about soil conservation and ecological restoration after severe climate events, such as long-lasting drought or flooding.

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The Role of Attention in Motion Extrapolation: Are Moving Objects ‘Corrected’ or Flashed Objects Attentionally Delayed?

Perception ◽

10.1068/p3066 ◽

2000 ◽

Vol 29 (6) ◽

pp. 675-692 ◽

Cited By ~ 46

Author(s):

Beena Khurana ◽

Katsumi Watanabe ◽

Romi Nijhawan

Keyword(s):

New York ◽

Moving Objects ◽

Reaction Times ◽

Cost Benefit ◽

Circular Path ◽

Perceptual Awareness ◽

Multiple Events ◽

Attentional Deployment ◽

Lag Effect ◽

Elementary Psychology

Objects flashed in alignment with moving objects appear to lag behind [Nijhawan, 1994 Nature (London) 370 256–257], Could this ‘flash-lag’ effect be due to attentional delays in bringing flashed items to perceptual awareness [Titchener, 1908/1973 Lectures on the Elementary Psychology of Feeling and Attention first published 1908 (New York: Macmillan); reprinted 1973 (New York: Arno Press)]? We overtly manipulated attentional allocation in three experiments to address the following questions: Is the flash-lag effect affected when attention is (a) focused on a single event in the presence of multiple events, (b) distributed over multiple events, and (c) diverted from the flashed object? To address the first two questions, five rings, moving along a circular path, were presented while observers attentively tracked one or multiple rings under four conditions: the ring in which the disk was flashed was (i) known or (ii) unknown (randomly selected from the set of five); location of the flashed disk was (i) known or (ii) unknown (randomly selected from ten locations), The third question was investigated by using two moving objects in a cost – benefit cueing paradigm, An arrow cued, with 70% or 80% validity, the position of the flashed object, Observers performed two tasks: (a) reacted as quickly as possible to flash onset; (b) reported the flash-lag effect, We obtained a significant and unaltered flash-lag effect under all the attentional conditions we employed, Furthermore, though reaction times were significantly shorter for validly cued flashes, the flash-lag effect remained uninfluenced by cue validity, indicating that quicker responses to validly cued locations may be due to the shortening of post-perceptual delays in motor responses rather than the perceptual facilitation, We conclude that the computations that give rise to the flash-lag effect are independent of attentional deployment.

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