Multi-objective optimisation of reliable product-plant network configuration.

Ensuring manufacturing reliability is key to satisfying product orders when production plants are subject to disruptions. Reliability of a supply network is closely related to the redundancy of products as production in disrupted plants can be replaced by alternative plants. However the benefits of incorporating redundancy must be balanced against the costs of doing so. Models in literature are highly case specific and do not consider complex network structures and redundant distributions of products over suppliers, that are evident in empirical literature. In this paper we first develop a simple generic measure for evaluating the reliability of a network of plants in a given product-plant configuration. Second, we frame the problem as a multi-objective evolutionary optimisation model to show that such a measure can be used to optimise the cost-reliability trade off. The model has been applied to a producer’s automotive light and lamp production network using three popular genetic algorithms designed for multi-objective problems, namely, NSGA2, SPEA2 and PAES. Using the model in conjunction with genetic algorithms we were able to find trade off solutions successfully. NSGA2 has achieved the best results in terms of Pareto front spread. Algorithms differed considerably in their performance, meaning that the choice of algorithm has significant impact in the resulting search space exploration

The “Digital Generation” is Learning to Read: Linguistic Factors of Eye Movement Parameters of Russian Schoolchildren of the 1st – 3rd Grades

The level of reading literacy of the modern "digital generation" is an acute and significant topic. To explore this problem in dynamics it is necessary to objectively record the parameters of reading skills development in modern children. The article presents the results of an experimental study of the reading mechanism of elementary school students, performed using eye tracking. Fifty-three pupils in grades 1–3 of Moscow schools participated in the experiment, with real texts from Russian textbooks as stimulus material. Eye movements were recorded while reading texts from the screen, and after each text a comprehension question was asked. The results indicated a direct correlation between oculomotor characteristics and reading skill. From grade 1 to grade 3, the duration and number of fixations, amplitude duration, and reading time for both word and letter decreased, while the number of words with one or missing fixation increased. There was also a grade-independent effect of word length and word frequency factors on reading speed and oculomotor activity for students in all grades. Both factors had a significant effect on reading time, the average fixation duration was more sensitive to the frequency factor than to the word length factor, while word length alone influenced the first fixation duration

Image in multimodal texts: does semantic connectivity with other text components affect visual perception parameters?

This article describes the results of a pilot experimental study of the perception and understanding of digital multimodal texts using the methods of eye-tracking and linguistic analysis. The aim of the study was to test the hypothesis that the distribution of visual attention during image perception in multimodal texts corresponds to the degree of semantic connectivity between the image and other parts of the stimulus. Multimodal texts in the format "static image + written utterance" selected from real expert practice were used as stimulus material. The study involved 84 participants of varying degrees of awareness of extremist discourse. In the first part of the experiment, respondents viewed and interpreted the content of the multimodal texts, while their eye movements were recorded; in the second part, respondents viewed, marked and commented on the same stimuli, with the task to find and explain the semantic correlations of image and verbal parts. The subjects of analysis were (a) the interest area (IA) dwell time normalized by area size (b) the number of views of the IA, (c) the average number of connections of the IA, reduced to (d) the average rank of connectivity of the area with other components. No significant differences were found depending on the respondents’ degree of awareness on extremist discourse, neither in the average number of IA correlations, nor in the distribution of ranks. IAs containing images of faces were found to have the highest number of views. In a single-factor analysis of variance, the ranks of connectivity had a significant effect on the number of IA views in all texts (p<0.05), with both direct and inverse correlations of these factors. According to these results, we can say that there is no universal connection between such parameters of viewing multimodal texts as dwell time normalized for area or the number of views and the number of connections of an image component with others. We suppose the effectiveness of the search for meanings that provide coherence to the components of a multimodal text does not depend on the amount of time and eye movements needed for visual perception, sufficient to understand the text

EXPERIMENTAL STUDY OF DEMOTIVATORS AND MEMES PERCEPTION COMPLEXITY

The article presents the results of a pilot study of the perception of the demotivator and meme genres. It was a part of an experimental study of psychophysiological and psycholinguistic features of perception and understanding of multimodal extremist texts. The aim of the study is to develop and test the hypothesis about the influence of genre on perception of multimodal texts. To test the hypothesis, we analyze the respondents’ eye movement data from the main experimental study (n = 60; 31 forensic linguists with anti-extremism practice, 29 non- experts). Research methods were eye-tracking and quantitative data processing. The following statistically reliable data were obtained: compared to memes, respondents looked at demotivators (1) for a longer time, made (2) shorter fixations, (3) with more of them, and also made (4) faster and (5) shorter saccades. These parameters may indicate a denser scanning pattern of viewing demotivators compared to memes and greater cognitive expenditure in assessing the semantic content of demotivator texts. The results of the study suggest a connection between genre and the degree of multimodal texts perception complexity. This provides an opportunity for further research in this direction and, in the future, will enable the development of norms of cognitive load of judicial linguists who analyse multimodal extremist texts

Can physiological sleepiness underlie consciously perceived sleepiness assessed with the Epworth sleepiness scale?

Methods of evaluation of substates of sleep and sleepiness differ in, at least, two respects. Although sleepiness has not been separated from other wake and sleep substates using yes-or-no criteria for sleep scoring, it would be consciously perceived and, therefore, assessed with a questionary. However, such subjective method was challenged by the finding suggesting a disconnect between two most widely used subjective and objective indicators of excessive daytime sleepiness (EDS), a score on the Epworth sleepiness scale (ESS) > 10 and a reduced latency to sleep onset (SOL), respectively. We examined whether these two EDS indicators differ in their association with physiological sleepiness, i.e., the polysomnographic indexes of elevated sleep pressure. In the afternoon hours, polysomnographic recordings were obtained throughout 54 50-min and 56 90-min napping attempts of 27 and 28 university students, respectively. Within some but not all 10-min intervals of the 50- or 90-min naps, each EDS indicator was validated against different objective polysomnographic indexes suggesting an association of EDS with elevated sleep pressure. Significant differences in sleep indexes were found between participants with short and longer SOL, but they disappeared right before the appearance of such differences between participants with higher and lower ESS score (usually at the 4th 10-min interval). This mismatch in timing of appearance of significant differences might be a plausible explanation for the lack of significant association between the ESS and SOL. Therefore, the physiologic underpinnings of the ESS can be uncovered despite such a disconnect between these two EDS indicators

“Struggle” between three switching mechanisms as the underpinning of sleep stages and the pattern of transition between them

Complex systems are occasionally switching between several qualitatively different modes of behavior, even in the absence of external influences. An example of such mode-switching behavior of a complex system is a sequence of changes in sleep stages observed on approximately 90-min interval of sleep cycle. We examined whether relatively stable stages and relatively rapid transitions between them can be linked to the observed markers of underlying processes of sleep–wake regulation. Using data on two napping attempts of each of 28 university students, we described how scores on principal components of the EEG spectrum and rates of transitions between stages can serve as objective markers of interaction between three underlying on–off switching mechanisms that, in turn, can reflect strengths of the mutually inhibiting drives for sleep, wake, and REM sleep. A sequence of transitions between five stages over sleep cycle can be viewed as representing a sequence of episodes of the “struggle” between these three permanently competing mechanisms. Each of typical stage transitions in sleep cycle can be interpreted as a relatively rapid change in state of one or two of these three on–off switchers. It seems that only one of them is capable to maintain the switch on state during a stage with the exception of transient stage 1 sleep during which all switches remain in switch off state. An aim of future research of stages and their transitions during normal and disturbed sleep can be aimed on identification of a switching mechanism involved into a certain disturbance of sleep

Can physiological sleepiness underlie consciously perceived sleepiness assessed with the Epworth sleepiness scale?

Abstract Methods of evaluation of substates of sleep and sleepiness differ in, at least, two respects. Although sleepiness has not been separated from other wake and sleep substates using yes-or-no criteria for sleep scoring, it would be consciously perceived and, therefore, assessed with a questionary. However, such subjective method was challenged by the finding suggesting a disconnect between two most widely used subjective and objective indicators of excessive daytime sleepiness (EDS), a score on the Epworth sleepiness scale (ESS) > 10 and a reduced latency to sleep onset (SOL), respectively. We examined whether these two EDS indicators differ in their association with physiological sleepiness, i.e., the polysomnographic indexes of elevated sleep pressure. In the afternoon hours, polysomnographic recordings were obtained throughout 54 50-min and 56 90-min napping attempts of 27 and 28 university students, respectively. Within some but not all 10-min intervals of the 50- or 90-min naps, each EDS indicator was validated against different objective polysomnographic indexes suggesting an association of EDS with elevated sleep pressure. Significant differences in sleep indexes were found between participants with short and longer SOL, but they disappeared right before the appearance of such differences between participants with higher and lower ESS score (usually at the 4th 10-min interval). This mismatch in timing of appearance of significant differences might be a plausible explanation for the lack of significant association between the ESS and SOL. Therefore, the physiologic underpinnings of the ESS can be uncovered despite such a disconnect between these two EDS indicators. Graphical abstrac

The Irrecoverable Loss in Sleep on Weekdays of Two Distinct Chronotypes Can Be Equalized by Permitting a >2 h Difference in Waking Time

Background: Our work/study culture is biased towards the circadian clocks of “morning types”, whereas “evening types” are forced to advance their weekday waking times relative to weekend waking times. Since the experimental research consistently reveals a >2 h difference between these two chronotypes in the positions of their endogenous circadian phases, we hypothesized the necessity to permit a >2 h difference between them in weekday waking times to equalize their irrecoverable loss in sleep on weekdays. Methods: A total of 659 and 1106 participants of online surveys identified themselves as morning and evening types, respectively. The hypothesis was tested by applying a model of sleep–wake regulation for simulating sleep times reported by 245 lecturers of these two types, and by comparison of sleep times of these types among these lecturers and 1520 students. Results: The hypothesis was supported by results showing that, if, on weekdays, an “average” morning type wakes at 6 a.m., the equalization of the weekday sleep loss of the two chronotypes would require the waking time of an “average” evening type to be no earlier than 8 a.m. Conclusions: These results may be implemented in a model-based methodology for the correction of weekday waking times to equalize weekday sleep loss