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The permutation flowshop scheduling problem is a vital production management concern of industries such as electronic product manufacturing and integrated circuit fabrication. In many studies, jobs are prioritized independently according to their features or properties. This article develops a new perspective by introducing the self-attention mechanism into scheduling for the first time. The job similarities are characterized by the dot-product of processing time matrices and taken as job priorities. Based on this idea, a new priority rule denoted by PRSAT is proposed, and a heuristic named NEHLJP2 is presented with makespan minimization. The computational results with the Taillard and VRF benchmarks and 640 random instances demonstrate that the new priority rule and heuristic dominate the existing ones at a nominal cost of computation time. [ABSTRACT FROM AUTHOR]

The blocking flow-shop scheduling problem, which is an NP-hard problem, has wide applications in industry. Many studies have focused primarily on single-objective optimization, such as minimizing the makespan or total flow time, which is insufficient for practical problems. In this study, a blocking flow-shop scheduling problem with bicriteria of the makespan and machine utilization is considered. A simple constructive heuristic, NEHCG, is proposed by developing new priority and tie-breaking rules based on the Nawaz–Enscore–Ham heuristic. In the new priority rule, the quartile deviation of job processing times is included for the first time, and the new tie-breaking rule is designed to break ties effectively in the insertion phase. Then, an improved constructive heuristic, PW_NEHCG, is presented by effectively combining NEHCG with an improved profile-fitting approach. Computational experiments show that the proposed constructive heuristics exhibit excellent performance compared to other well-known heuristics. [ABSTRACT FROM AUTHOR]

This paper first explores spatial distributions and patterns of COVID-19 case rates (cases/100,000 people) and mortality rates (deaths/100,000 people) and their disparities between urban and rural counties in the contiguous US. A county-level social vulnerability index was created using principal component analysis. Social vulnerability components were regressed against both county case and mortality rates. Results suggest that hotspots of case and mortality rates are clustered in Midwest and Upper-Midwest US. We found substantial disparities in case and mortality rates between urban and rural counties. County social vulnerability was positively correlated with both case and mortality rates suggesting counties with higher social vulnerability had higher case and mortality rates. Relationships between social vulnerability components and case and mortality rates vary across the conterminous US. Additionally, counties with increased racial and ethnic minorities, higher percentages of minors, and lower median household income are associated with higher COVID-19 case and mortality rates. [ABSTRACT FROM AUTHOR]

The permutation flowshop scheduling problem has been widely studied under static environment by assuming machines and jobs are available at the time of zero. However, in reality, new orders arrive at production systems randomly, which leads to sheer complexity in scheduling due to the dynamic changes given various constraints of resources. Previous studies simply attach new orders directly after the existing schedule. Recent study shows mixing jobs of old and new orders could result in better scheduling solutions. But the heuristic algorithms are still lacking to implement the job mixing policy. To address this problem, a novel scheduling strategy is herein proposed by integrating match-up strategy and real-time strategy (MR) in order to make use of the remaining time before the old order due date. Based on the new MR strategy, eleven new heuristics are introduced with ten existing and one new priority rules. Computational results illustrate the effectiveness of the new heuristics. A digital tool is developed for ease of application of these heuristics, and it is validated by case studies. [ABSTRACT FROM PUBLISHER]

Stable isotopes of water have been widely used in understanding the hydrological functions of alpine inland catchments. This study identifies dominant runoff generation mechanisms based on isotopic data (δ18O andδ2H) of 487 rainwater and river-water samples from three tributaries in the Tarim River Basin in China for the period May–September 2013. The isotope hydrograph separation results provide a comprehensive overview of the rainfall influence on hydrological processes. Stream water and groundwater have varied responses to different intensities of rainfall events. Only a small proportion of rainfall is directly transported to the stream during such events. An inconsistent temporal trend of event water contribution is observed in the three catchments. The average fractional contributions of rainfall for the Tizinafu, Kumalak and Huangshuigou rivers are 10.3% (±1.1%), 9.7% (±2.9%) and 8.7% (±2.4%), respectively. [ABSTRACT FROM PUBLISHER]

Automatic generation of multi-scale representations from the same spatial data source has been the research focus in map generalization for a long time. Based on the Fourier technique, this paper proposes a continuous, multi-scale representation model for progressive transformation of cartographic curves on the Internet. In our method, all the curves, whether closed or open, are depicted as periodical functions which are further expressed as Fourier series. The convergence degrees of the Fourier series are explored for different kinds of curves, and truncating frequencies are derived based on the similarity between the original and reconstructed curves. Using information theory and the Radical Law in cartography, the relationship between map scales and Fourier frequencies is established. Based on the proposed multi-scale model, we also introduce the principles and implementation of a progressive transmission method. Our method is evaluated using the contours from a topographic map. The results show that our model is a valid approach to multi-scale representation of cartographic curves. [ABSTRACT FROM AUTHOR]

A new heuristic based on the Nawaz–Enscore–Ham algorithm is proposed in this article for solving a permutation flow-shop scheduling problem. A new priority rule is proposed by accounting for the average, mean absolute deviation, skewness and kurtosis, in order to fully describe the distribution style of processing times. A new tie-breaking rule is also introduced for achieving effective job insertion with the objective of minimizing both makespan and machine idle time. Statistical tests illustrate better solution quality of the proposed algorithm compared to existing benchmark heuristics. [ABSTRACT FROM AUTHOR]

Large amounts of time series of spatial snapshot data have been collected or generated for the monitoring and modeling of environmental systems. Those time series of data also provide the opportunity to study the movements and dynamics of many different natural phenomena. While the snapshot organization is conceptually simple and straightforward, it does not directly capture or represent the dynamic characteristics of the phenomena. This study presents computational methods to identify dynamic events from time series of spatial snapshots. Events are represented as directed spatiotemporal graphs to characterize their initiation, development, movement, and cessation. Graph-based algorithms are used to analyze the dynamics of the events. The method is applied to time series of high-resolution radar reflectivity images during one of the deadliest storm outbreaks that impacted 15 states of southeastern United States between 23 and 29 April 2011. As shown in this case study, convective storm events identified using our methods are consistent with previous studies, and our analysis confirms that the left split/merger occurs more than right split/merger in those convective storm events, which confirms theory, numerical simulations, and other observed case studies. While this study does not differentiate between storm modes, the method shows potential for capturing a more detailed climatology of precipitation characteristics. [ABSTRACT FROM AUTHOR]