The Study of a Structural and Electronic Properties of Two-Dimensional Flat Layer Arsenene Using Planewaves Density Functional Calculation

We explore the structural and electronic properties of a single layer arsenene using the state of art, first principle approach from density functional theory (DFT). All the calculation was conducted using an open source DFT code, adopted the planewaves (PWs) method by Quantum Espresso (QE). The calculation utilized an exchange correlation potential of electron parametrized by Perdew-Burke-Ernzerhof (PBE) under generalized gradient approximation (GGA) functional scheme. Meanwhile, the pseudopotential assigned for the core electron is the projector typed augmented-wave with the core potential correction, generated using "atomic" code. All those parameters resulted an optimized structure of the honeycomb arsenene with lattice constant of 4.4971 Ǻ. The arsenene layer occupy a bond length value of 2.5964 Ǻ as measured between its neighbouring bonded atoms. From an optimized structure, we explore its electronic bandstructure plotted from 3 highly symmetries point for 2-dimensional (2D) material known as ‘’, ‘’ and ‘’ with 3 electron pathways. The total number of bands considered in bandstruture plotting is 10, where 5 bands will consider as valance bands while another 5 is conduction bands. The bandstructure shows that a single layer flat arsenene exhibits the characteristics of a conductor due to the overlapping of band near to Fermi level. Dirac cone were also noticed near to the Fermi energy level of the bandstructure. Lastly, we study the total electron density for the whole structure to reveal its bonding characteristics. The contour plot of electron densities between two bounded atoms displayed a pure covalent bond characteristic. The findings of this work is expected to contribute to the key of the electronic devices development, optoelectronics, and sensor devices based on 2D material technology.Keywords: flat layer arsenene, density of state, electron density, electronic band structure

A multi-DOF rotary 3D printer: machine design, performance analysis and process planning of curved layer fused deposition modeling (CLFDM)

Purpose The purpose of this paper is to design and develop a rotary three-dimensional (3D) printer for curved layer fused deposition modeling (CLFDM), and discuss some technical challenges in the development. Design/methodology/approach Some technical challenges include, but are not limited to, the machine design and control system, motion analysis and simulation, workspace and printing process analysis, curved layer slicing and tool path planning. Moreover, preliminary experiments are carried out to prove the feasibility of the design. Findings A rotary 3D printer for CLFDM has been designed and developed. Moreover, this printer can function as a polar 3D printer for flat layer additive manufacturing (AM). Compared with flat layer AM, CLFDM weakens the staircase effect and improves geometrical accuracy and mechanical properties. Hence, CLFDM is more suitable for parts with curved surfaces. Research limitations/implications Double extruders have brought improved build speed. However, this paper is restricted to complex process planning and mechanical structures, which may lead to collisions during printing. Meanwhile, the rotation range of the nozzle is limited by mechanical structures, affecting the manufacturing capability of complex curved surfaces. Originality/value A novel rotary 3D printer, which has four degrees of freedom and double extruders, has been designed and manufactured. The investigation on the prototype has proved its capability of CLFDM. Besides, this rotary 3D printer has two working modes, which brings the possibility of flat layer AM and CLFDM.

Седиментация малоконцентрированной взвести стоксовских частиц в перемешиваемом слое с движущейся свободной границей

The problem of sedimentation of polydisperse low-concentrated Stokes particles under the conditions of mixing if the carrier medium in a flat layer with a moving free surface is considered using a diffusion-kinetic model of the motion of the dispersed phase in the suspension