928 research outputs found
Uniaxial Strain Induced Topological Phase Transition in Bismuth-Tellurohalide-Graphene Heterostructures
We explore the electronic structure and topological phase diagram of
heterostructures formed of graphene and ternary bismuth tellurohalide layers.
We show that mechanical strain inherently present in fabricated samples could
induce a topological phase transition in single-sided heterostructures, turning
the sample into a novel experimental realisation of a time reversal invariant
topological insulator. We construct an effective tight binding description for
low energy excitations and fit the model's parameters to ab initio band
structures. We propose a simple approach for predicting phase boundaries as a
function of mechanical distortions and hence gain a deeper understanding on how
the topological phase in the considered system may be engineered.Comment: 20 pages, 7 figures, Accepted Manuscrip
Vehicle Routing Approach for Lean Shop-Floor Logistics
In order to satisfy the material supply needs of large scale shop-floors and
production systems, various logistics solutions are applied. In lean
manufacturing enterprises, the material supply is pulled by the demands of
manufacturing/assembly processes; therefore, a milkrun service is often
applied to support the production without glitches. The milkrun logistics
planning is a special case for vehicle routing problem (VRP), and requires
effective approach to solution in order to satisfy various constraints, and
minimize the cost of service. This study gives an overview about lean
logistics as well as the most efficient VRP solver algorithms. Furthermore, a
novel initial solution with generation heuristics is proposed, which is
specially focused on flexible milkrun planning. In order to demonstrate the
capabilities of the solution, a software environment is developed as a
demonstration that focuses on the main industrial requirements of logistics
planning like effective layout definition, quick response of the delivery
service and effective order handling
Application of Additive Technology in Precision Casting
In this paper the surface of the prepared test specimens had been examined with light microscopy and surface roughness measurements. In order to improve the surface smoothness of PLA specimens, application of ethyl acetate was required. After this surface treatment, microscopic images were taken again. The melting and decomposition temperatures of the materials had been determined using derivatography. The chosen method was precision casting with gypsum molding. Also, the plaster molds had been burnt out according to the predefined melting and firing diagram. The measurement series shows that the samples produced by 3D printing can also be used in the field of precision casting. They provide greater freedom of design, more sophisticated pieces, and prototypes can be finished in a shorter amount of time
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