Electrospinning-Derived PLA/Shellac/PLA Sandwich—Structural Membrane Sensor for Detection of Alcoholic Vapors with a Low Molecular Weight

The development of gas sensors for detecting alcoholic vapors with a low molecular weight is essential for environmental protection, industrial process control, and the monitoring of the living atmosphere in daily life to avoid health problems in human beings. Here, poly (lactic acid) (PLA)/shellac/PLA sandwich-structural membranes were fabricated via an electrospinning approach and the interaction with alcoholic vapors with a low molecular weight was investigated. It was found that the PLA/shellac/PLA sandwich-structural membrane exhibited fast response to the alcoholic vapors with low molecular weight, especially for methanol vapor. After being treated with alcohol vapor with a low molecular weight, the PLA/shellac/PLA sandwich-structural membrane could change its transmission in a short time (~5 s) and with a concentration of 10 wt% of methanol (ethanol) in water. In the meantime, the PLA/shellac/PLA sandwich-structural membrane can hopefully be potentially used again after evaporating the alcoholic vapor at an elevated temperature.

CAD-integrated Parametric Design Cycle for Structural Membranes

The design cycle of membrane structures consists of three interactive and highly non-linear disciplines. Formfinding is performed in order to find a geometry that allows the prestressed structure to carry loads through tension only. Once a formfound geometry is set, structural analysis needs to assess the structure's safety and usability. The most challenging step is the cutting pattern generation, which aims at finding the planar pieces which can be elevated to build spatial membrane structures with a minimum deviation from the desired shape and prestress state.<br/> Isogeometric B-Rep Analysis (IBRA) allows the designer to perform analyses on the original CAD model without leaving the CAD environment. High quality is ensured for the geometry and the mechanical approximation by using Non-Uniform Rational B-Splines (NURBS). Additionally, the topology information of multipatches can be transferred to the analysis in order to enrich the design space. Trimmed and coupled surfaces can thus be included in the analysis. Parametric models allow the designer to examine a large variety of geometrical and mechanical entities with one model.<br/> The advantages of the CAD-integration with IBRA for the highly interactive design of structural membranes are shown in this contribution.

Practical expressions to calculate the main vertical actions on load-bearing columns/walls to Eurocode

Purpose The aim of this review study is to present useful and practical expressions to compute the design vertical actions on load-bearing columns/walls of typical building structures on the basis of EN 1991: Eurocode 1. Design/methodology/approach It is derived by a typical case in which wind actions, snow actions and permanents actions are loading a roof construction. The results are finally used to calculate the loading on columns/walls. Both ultimate limit state and serviceability limit state are considered. Findings From an instructive point of view, the advantage of this method is that it is simplified, general, not time-consuming, and it can be standardised to typical building structures. Research limitations/implications A number of example applications are introduced to illustrate the calculation procedure. Practical implications From an educational point of view, this problem is of interest to civil engineering students because the reviewed method is not cumbersome or time-consuming. Social implications From an engineering educational point of view, this problem is of interest to civil engineering students because the reviewed method is not cumbersome or time-consuming. Originality/value New formulated expressions to calculate the loadings on structural membranes based on Eurocode are presented.