During continuous peeling, a central polymer rod free of visible defects was continuously extruded while being peeled at the die exit. Continuous peeling can occur at flow rates orders of magnitude higher than those at which initial surface cracking is observed. Thus, if continuous peeling can be controlled it may have potential industrial applications. The aim of this work was to study how different extrusion parameters (temperature, flow rate, die length and diameter) affect the presence of continuous peeling. The melt exiting the die has been filmed to link physical measurements and observations and to determine whether or not continuous peeling is present. Different criteria have been considered to represent the extrusion conditions under which continuous peeling may occur. Surface tension criteria can be used to try to predict the appearance and disappearance of continuous peeling. A correlation formula is also proposed for the rod diameter in terms of surface tension. Our results show that the ratio of the rod diameter to the die diameter is approximately 25% greater in the case of short-orifice dies (L/D ≈ 0) than for long capillaries (L/D ≈ 10). The correlations obtained allow analysis and discussion of flow regimes for possible applications. 相似文献
The split and hyperbolic (countercomplex) octonions are eight‐dimensional nonassociative algebras over the real numbers, which are in the form , where em's have different properties for them. The main purpose of this paper is to define the split‐type octonion and its matrix whose inputs are split‐type octonions and give some properties for them by using the real quaternions, split, and hyperbolic (countercomplex) octonions. On the other hand, to make some definitions, we present some operations on the split‐type octonions. Also, we show that every split‐type octonions can be represented by 2 × 2 real quaternion matrix and 4 × 4 complex number matrix. The information about the determinants of these matrix representations is also given. Besides, the main features of split‐type octonion matrix concept are given by using properties of real quaternion matrices. Then, 8n × 8nreal matrix representations of split‐type octonion matrices are shown, and some algebraic structures are examined. Additionally, we introduce real quaternion adjoint matrices of split‐type octonion matrices. Moreover, necessary and sufficient conditions and definitions are given for split‐type octonion matrices to be special split‐type octonion matrices. We describe some special split‐type octonion matrices. Finally, oct‐determinant of split‐type octonion matrices is defined. Definitive and understandable examples of all definitions, theorems, and conclusions were given for a better understanding of all these concepts. 相似文献
Despite the great promise of printed flexible electronics from 2D crystals, and especially graphene, few scalable applications have been reported so far that can be termed roll‐to‐roll compatible. Here we combine screen printed graphene with photonic annealing to realize radio‐frequency identification devices with a reading range of up to 4 meters. Most notably our approach leads to fatigue resistant devices showing less than 1% deterioration of electrical properties after 1000 bending cycles. The bending fatigue resistance demonstrated on a variety of technologically relevant plastic and paper substrates renders the material highly suitable for various printable wearable devices, where repeatable dynamic bending stress is expected during usage. All applied printing and post‐processing methods are compatible with roll‐to‐roll manufacturing and temperature sensitive flexible substrates providing a platform for the scalable manufacturing of mechanically stable and environmentally friendly graphene printed electronics.