Analysis of Crosstalk Problem in Multi-Twisted Bundle of Multi-Twisted Wire Based on BSAS-BP Neural Network Algorithm and Multilayer Transposition Method

Twisted wire used in complex systems has the ability to reduce electromagnetic interference, but crosstalk within the wire is not easy to obtain. This paper proposes a method to predict the crosstalk of multi-twisted bundle of multi-twisted wire (MTB-MTW). A neural network algorithm based on back propagation optimized by the beetle swarm antennae search method (BSAS-BPNN) is introduced to mathematically describe the relationship between the twist angle of the wire harness and the per-unit-length (p.u.l) parameter matrix. Considering the symmetry of the model, the relationship between the unresolved angle of the BSAS-BPNN algorithm and the p.u.l parameter matrix is processed by using the multilayer transposition method. Based on the idea of the cascade method and the finite-difference time-domain (FDTD) algorithm in Implicit-Wendroff format, the crosstalk of the wire is obtained. Numerical experiments and simulation results show that the new method proposed in this paper has better accuracy for the prediction of the model. The new method can be generalized to the MTB-MTW model with any number of wires. All theories provide preliminary theoretical basis for electromagnetic compatibility (EMC) design of high-band circuits.

Self-Compacting Concrete Reinforced with Twisted-Bundle Macro-Synthetic Fiber

The use of self-compacting concrete (SCC) reinforced with fibers has great potential in the precast concrete industry as the concrete can be delivered straight into the moulds, without any vibration or compacting effort. Similarly, it has the potential to replace traditional steel reinforcement depending on the design requirements. Novel synthetic fibers have recently become available in the market, but still, limited information is available on the performance of SCC reinforced with such fibers. This paper investigates the use of twisted-bundle macro-synthetic fiber in self-compacting concrete. Three different concrete mixtures with fiber dosage of 4, 6, and 8 kg/m3 were produced in large scale batches, and their performance was compared in terms of slump-flow, compressive strength, split tensile strength, modulus of elasticity, and flexural strength. Moreover, a comprehensive evaluation of the post-cracking residual strength is presented. It was found that the mixture with 4 kg/m3 fiber content has the most satisfactory flowability, whereas 8 kg/m3 mixture achieved the highest residual flexural strength. Based on the observed post-cracking behavior, a simplified stress-crack opening constitutive law is proposed. Since the fiber dosage affects the residual flexural strength, a factor related to fiber content is recommended while determining the ultimate residual flexural strength.

Conjecture on the Lateral Growth of Type I Collagen Fibrils

Type I collagen fibrils have circular cross sections with radii mostly distributed in between 50 and 100 nm and are characterized by an axial banding pattern with a period of 67 nm. The constituent long molecules of those fibrils, the so-called triple helices, are densely packed but their nature is such that their assembly must conciliate two conflicting requirements. One is a double-twist around the axis of the fibril induced by their chirality and the other is a periodic layered organization, corresponding to the axial banding, built by specific lateral interactions. We examine here how such a conflict could contribute to the control of the radius of a fibril. We develop our analysis with the help of two geometrical archetypes: the Hopf fibration and the algorithm of phyllotaxis. The first one provides an ideal template for a twisted bundle of fibres and the second ensures the best homogeneity and local isotropy possible for a twisted dense packing with circular symmetry. This approach shows that, as the radius of a fibril with constant double-twist increases, the periodic layered organization can not be preserved without moving from planar to helicoidal configurations. Such changes of configurations are indeed made possible by the edge dislocations naturally present in the phyllotactic pattern. The distribution of those defects is such that the lateral growth of a fibril should stay limited in the observed range. Because of our limited knowledge about the elastic constants involved, this purely geometrical development stays at a quite conjectural level.