Spectral Fingerprint Investigation in the near Infra-Red to Distinguish Harmful Ethylene Glycol from Isopropanol in a Microchannel

Ethylene glycol (EG) and isopropanol (ISO) are among the major toxic alcohols that pose a risk to human health. However, it is important to distinguish them, since EG is more prone to cause renal failure, and can thus be more dangerous when ingested than ISO. Analysis of alcohols such as isopropanol and ethylene glycol generally can be performed with a complex chromatographic method. Here, we present an optical method based on absorption spectroscopy, performed remotely on EG-ISO mixtures filling a microchannel. Mixtures of ethylene glycol in isopropanol at different volume concentrations were analyzed in a contactless manner in a rectangular-section glass micro-capillary provided with integrated reflectors. Fiber-coupled broadband light in the wavelength range 1.3–1.7 µm crossed the microchannel multiple times before being directed towards an optical spectrum analyzer. The induced zig-zag path increased the fluid–light interaction length and enhanced the effect of optical absorption. A sophisticated theoretical model was developed and the results of our simulations were in very good agreement with the results of the experimental spectral measurements. Moreover, from the acquired data, we retrieved a responsivity parameter, defined as power ratio at two wavelengths, that is linearly related to the EG concentration in the alcoholic mixtures.

Wave propagation in tapered periodic curved meta-frame using Floquet theory

In this work, the elastic wave propagation and dispersion characteristics of a curved tapered frame structure is investigated analytically. Separately, wave propagation through uniform curved and straight tapered beam were reported in the existing literature; however, no literature reports the influence of simultaneous bent and taper on the wave propagation. In particular, the band characteristics for the curved and tapered beam with two types of cross-sections, i.e., rectangular and circular, are presented. The paper elucidates that introducing a small periodic bent angle cross-section produces a complete, viz. axial and flexural band gap in the low-frequency region, and conicity enhances the width of the band. It is also evidenced that a curved tapered frame with a solid circular cross-section induces a wider band gap than the rectangular section. A complete first normalized bandwidth of 159% is achievable for the circular cross-section and 123% in the case of the rectangular section. The complete result is presented in a non-dimensional framework for wider applicability. An analysis of a finite tapered curved frame structure also demonstrates the attenuating characteristics obtained from the band structure of the infinite structure. The partial wave mode conversion, i.e., generation of coupled axial and flexural mode from a purely axial or flexural mode in an uncoupled medium is observed. This wave conversion is perceived in reflected and transmitted waves while this curved tapered frame is inserted between the two uniform cross-section straight frames.

Determinación del error inducido al usar una relación esfuerzo-deformación lineal en el cálculo del momento de fluencia de una sección de viga de concreto reforzado

Nowadays, the teaching in civil engineering courses related to the analysis and design of reinforced concrete beams subjected to pure bending is based on models that use simplifications to facilitate calculations. When analyzing the plastic capacity of a rectangular section, its yield moment is usually calculated assuming that the stress-strain relationship can be idealized using a straight line. However, the validity of this relationship is only verified when the levels of compressive stress are less than 45% of the compressive strength of concrete f´c. For this reason, it is convenient to make a rigorous review over the convenience of using this simplification at medium and to high stresses close to failure. This work studies how a reinforced concrete section behaves according to the simplified model and compares its results to those obtained when using the function proposed by Hognestad in 1955 (still vigent). Interestingly, as a general conclusion, it can be said that the results predicted by the simplified model fit well respect to those obtained using the greatest mathematical rigor.

Effect of Bilge Radius and Bilge Keel Height on Roll Damping Performance of Floating Structures

A round bilge with a bilge keel structure is a key element which can alleviate roll motions of ships and floating structures by transferring the roll momentum of a floating body into the kinetic energy of water. This study presents a practical guide to properly designing a bilge radius and bilge keel height of a barge-shaped and tanker-shaped FPSOs. A parametric study to figure out the effect of bilge radius and bilge keel height on the roll damping performance is conducted through a series of numerical roll free decay simulations based on Computational Fluid Dynamics (CFD). The bilge radius is normalized by the half breadth of ship, and the bilge keel height is normalized by the maximum bilge keel height which is limited by the molded lines of a side shell and bottom shell. In addition, it is investigated to identify how the roll damping performance of a rectangular section differs from the result of a typical round bilge section with maximum available bilge keel height.

Spray Pattern of Aluminum Coatings with the Rectangular Cross-Section Nozzle Calculated by the Computational Fluid Dynamics (CFD) in High-Pressure Cold Spray

In the cold spray process; cross-sectional shape of the nozzle has a significant effect on spray pattern of coatings. The circular exit nozzle is parabolic in shape. So; spray pattern with the rectangular nozzle is wider than that with the circular spray nozzle. The goal of this investigation is to establish a design for the cold spray gun nozzle to gain more uniform spray profile of coatings. We have investigated the influence of expansion ratio; nozzle total length and the ratio of nozzle length of divergent section and parallel section of rectangular nozzle on behaviors of gas and particle by the computational fluid dynamics (CFD) in high pressure cold spraying. We have studied copper particles so far. In this study; we will examine aluminum particles. First; we investigate the influence of the size and shape of the rectangular section nozzle on the velocity; temperature; and particle distribution of aluminum particles by CFD. After that; the rectangular section nozzles were fabricated and coating formation experiments were conducted; spray patterns and coating cross-sectional structures were observed; and coating adhesion was also evaluated. The nozzle material was polybenzimidazole resin; which is difficult for aluminum particles to attach to nozzle walls.

CALCULATION OF THE STABILITY OF A PLANE BENDING OF BEAMS WITH A VARIABLE CROSS-SECTIONAL WIDTH

The article proposes a technique for calculating the side buckling of beams of variable rectangular section based on the energy method. This method is considered on the example of a two-section cantilever beam of variable width under the action of a concentrated force. The twist angle function was set in the form of a trigonometric series. As a result, the problem is reduced to a generalized eigenvalue problem.

Recommendations for Designing Wooden Arches on Metal-toothed Plates

This paper presents the findings of the pilot studies and recommendations for designing of two-hinged wooden arches. The prototype models of wooden arches with the span of 6mand the rise of 1m were designed. The models had a rectangular cross-section of 180x40mm and a T-section of 180x40mm with a plywood plate with the thickness of 6 mm and the width of 500mm. The main objective of the T-section was to ensure the stability of the arch. Each arch was composed of six segments –boards joined by clamping plates. The bowstring truss including two inclined tie bars enables carrying asymmetric loads and provides in-plane stability of the arch. A methodology for laboratory testing of the prototype models of wooden arches subjected to different types of loads was developed. Two prototypes of wooden arches were tested with rectangular cross-sections and two T-section ones subjected to the loading across the span, and two prototypes subjected to the half-span loading. In total, eight arches were tested. Deflections of arches, cross-section deformations and arch thrust force were recorded. The arches were tested until failure. The results of testing revealed insufficient stability of the arches with rectangular cross-section in the horizontal plane. For the arches with T-section the whole arch rib was damaged, the in-plane stability was ensured by the T-section. The collapsing force of the T-section arch was about 1.3 times greater than the collapsing force of the rectangular section arches.