Theoretical foundations of triboelectric nanogenerators(TENGs)

Triboelectric nanogenerator(TENG) is an emerging powerful technology for converting ambient mechanical energy into electrical energy through the effect of triboelectricity. Starting from the expanded Maxwell’s equations, the theoretical framework of TENGs has been gradually established. Here, a review is given about its recent progress in constructing of this general theory. The fundamental mechanism of TENGs is constructed by the driving force—Maxwell’s displacement current, which is essentially different from that of electromagnetic generators. Theoretical calculations of the displacement current from a threedimensional mathematical model are presented, as well as the theoretical studies on the TENGs according to the capacitor models. Furthermore, the figure-of-merits and standards for quantifying the TENG’s output characteristics are discussed, which will provide important guidelines for optimizing the structure and performance of TENGs toward practical applications. Finally,perspectives and challenges are proposed about the basic theory of TENGs and its future technology development.

A Century in Retrospect: Several Theoretical Problems of Russian Formalism From a Paradigm Perspective

The study of Russian Formalism from a paradigm perspective has an integrative methodological value compared with traditional approaches. From the three different levels(philosophy, knowledge and operation) inherent to the paradigm perspective, this paper reexamines several theoretical problems that were previously thought to be settled: the theoretical construction of Russian Formalism, its development and its theoretical foundation. It shows that the Russian Formalistic paradigm is not only a literary phenomenon, but also relates to the fields of linguistics and philosophy, and at the knowledge level consists of the three schools of Formalistic Literature, Formalistic Linguistics and Formalistic Functionalism. The paper also points out that the lifespan of the paradigm from beginning to decline was longer than the ten years generally believed by scholars. Finally, the paradigm's theoretical foundation does not originate from Husserl's phenomenology or the literary schools related to it, as previously assumed, but from the linguistic methodologies of historical comparativism and structuralism, as well as the common aesthetic theory within philosophy.

Overview of current design and analysis of potential theories for automated fibre placement mechanisms

Automated fibre placement(AFP) systems have successfully intensified the demand for high-quality composite component manufacturing in both the military and civilian fields. One of the main elements of these systems is the AFP mechanism for accomplishing individual fibre delivery,clamp/cut/restart(CCR) and the consolidation process, and it consists of several functional submechanisms presenting strong coupling relationships and motion sequences. This review aims to summarize the development of AFP mechanisms and the associated research achievements and provide insight into the research challenges in promoting innovative design in such mechanisms. The systematic development of AFP systems is reviewed in detail, and subsequently, engineering tendency and the general principle of AFP mechanisms are introduced. Focusing on the mechanism design of AFP sub-mechanisms, including the creel assembly CCR and compaction mechanisms,the mechanical schemes as well as the AFP process parameter control are discussed. To improve system reliability and fully optimise AFP mechanisms, the essential theoretical foundation for AFP mechanisms are provided. It is believed that this attempt will help to change the design and optimisation of similar complete mechanisms. Based on the reviewed research, overall remarks and perspectives are presented to serve as a guide for exploring the possibility of novel easy-to-use and cost-effective integrated AFP applications.