Search

Distributed systems have been widely used in many safety‐critical areas. Any abnormalities (e.g., service interruption or service quality degradation) could lead to application crashes or decrease user satisfaction. These things may cause serious economic losses. Among the various quality assurance approaches for distributed systems, log‐based anomaly detection (LAD) has become a popular research topic. Its popularity relates to system logs being able to record and reveal important run‐time information. This paper presents a general LAD framework for distributed systems. Log grouping and feature‐pattern mining are two crucial LAD components that impact on the anomaly‐detection effectiveness. We also present a systematic survey of techniques in these two directions; propose classification frameworks for log grouping and feature patterns; and summarize four log‐grouping techniques and five feature patterns (which refer to invariant relationships among logs that can be used for anomaly detection). To evaluate their applicability, we report on the findings when applying existing techniques to Ray, a popular industrial distributed system. Based on these findings, several open issues are identified, which provide potential guidance for future research and development. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: The development of switchable solvent‐free multicomponent reactions to build high‐value‐added products is an important demand for organic synthesis. Herein, we detailed the successful implementation of a switchable strategy for the construction of diverse 4‐fluoroalkyl‐1,4‐dihydropyrimidines and 4‐fluoroalkyl‐pyrimidines via a solvent/additive‐free [3 + 2 + 1] annulation, starting from readily available enamines, trifluoroacetaldehyde hydrate or 1‐ethoxy‐2,2‐difluoroethanol and amidines hydrochloride. This reaction conforms to the concept of green synthesis, and provides a new avenue to access valuable fluorinated heterocycles. [ABSTRACT FROM AUTHOR]

The elaboration of step-economy and catalytic approaches for accessing diverse fluorinated heterocyclics is highly desirable. Described herein is a radical-polar crossover enabled three-component cyclization to polysubstituted fluoropyrazoles by using CF 2 Br 2 as a novel C1F1 synthon. Mechanistic experiments revealed that the in situ generation of the reactive intermediate gem -difluorovinylimine ion is the key to this transformation. This protocol unlocks the novel reactivity of CF 2 Br 2 and adds significant synthetic values to fluorine chemistry.