Shear properties and load–deflection response of cross–ply glass–epoxy composite short–beams subjected to three‐point‐bending tests,and the effect of moisture absorption

The extensive use of composites in aerospace, chemical, marine, and structural applications leads to exposure to humidity and water immersion. Hence, there is a need to study the effect of moisture absorption on the mechanical properties of composite materials, especially the matrix dominated properties, such as the interlaminar shear strength (ILSS). The horizontal shear test with a short‐beam specimen in three‐point‐bending is used as a general method of evaluation for the shear properties in fiber‐reinforced composites because of its simplicity. In this work, the ILSS of cross‐ply glass‐epoxy resin composites is determined in seven different fiber directions with short‐beam three‐point‐bending tests, before and after moisture conditioning. It is found that moisture absorption reduces ILSS and stiffness of the examined composites whereas it leads to larger failure deflections. It is also found that the direction of fibers strongly affects the load–deflection response and the ILSS of the dry and conditioned specimens. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Hydroelastic optimization of a keel fin of a sailing boat: a multidisciplinary robust formulation for ship design

The paper presents a formulation for multidisciplinary design optimization of vessels, subject to uncertain operating conditions. The formulation couples the multidisciplinary design analysis with the Bayesian approach to decision problems affected by uncertainty. In the present context, the design specifications are no longer given in terms of a single operating design point, but in terms of probability density function of the operating scenario. The optimal configuration is that which maximizes the performance expectation over the uncertain parameters variation. In this sense, the optimal solution is “robust” within the stochastic scenario assumed. Theoretical and numerical issues are addressed and numerical results in the hydroelastic optimization of a keel fin of a sailing yacht are presented.     

Isotropic Image Analysis for Improving CBR Forecasting

A novel hybrid forecasting Case-Based Reasoning (CBR) system is presented in this interdisciplinary study in which an isotropic buffer operator is applied for case-based creation. Commonly used as an image analysis technique by commercial Geographic Information Systems (GIS), the buffer operator in this particular system calculates the area of an oil slick for prediction and visualization tasks. The use of the buffer operator improves the quality of the data used by the system and in consequence the quality of the results obtained. The system generates predictions by using historical data on oil-slick formation following a spill.     

Structural and physical properties of microwave synthesized orthorhombic perovskite erbium chromite ErCrO3

Rare-earth chromite ErCrO₃ powder was synthesized from metal nitrate precursors using microwave synthesis. (Micro-) structural characterizations were performed using X-ray diffraction, Rietveld refinement, High Resolution Transmission Electron Microscopy and Electron Micro-Diffraction. Magnetization vs. temperature measurements revealed anti-ferromagnetism with T_Neel ≈ 135 K. An anti-ferrimagnetic moment of ≈0.4 μ_B was determined from magnetization vs. applied field measurements. Temperature dependent impedance spectroscopy (IS) indicated 3 dielectric relaxation processes: electrode interface, grain boundary and bulk. The intrinsic bulk activation energy was found to be 0.27 eV and the dielectric permittivity ?_r was ≈23 in excellent agreement with Clausius-Mossotti predictions and showed no perceptible temperature dependence. This and the low ?_r value suggested that ErCrO₃ is a dielectric rather than ferroelectric compound. IS measurements with applied dc bias revealed the signs of an unconventional type of Schottky barrier at the metallic Au electrode/ceramic ErCrO₃ interface.     

New trends on e-Procurement applying semantic technologies: Current status and future challenges

The present paper introduces and reviews existing technology and research works in the field of e-Procurement. More specifically this survey aims to collect those relevant approaches that have tackled the challenge of delivering more advanced and intelligent e-Procurement management systems due to its relevance in the industry to afford more timely, adaptable and flexible decisions in purchasing processes. Although existing tools and techniques have demonstrated their ability to manage e-Procurement processes as a part of a supply management system there is a lack of interoperability among tools, tangled dependencies between processes or difficulties to exploit existing data and information to name a few that are preventing a proper use of the new dynamic and data-based environment. On the other hand semantic-based technologies emerge to provide the adequate building blocks to represent domain-knowledge and elevate the meaning of information resources through a common and shared data model (RDF) with a formal query language (SPARQL) and accessible via the Internet Protocols. In this sense the Linked Data effort has gained momentum to apply the principles of the aforementioned initiative to boost the re-use of information and data across different tools and processes. That is why authors review both existing open issues in the context e-Procurement with special focus on public procurement and semantic-based approaches to address them. To do so a preliminary research study is conducted to assess the state of the art in the context of e-Procurement and semantic-based systems. Afterwards main drawbacks of existing e-Procurement systems are presented to narrow down in semantic-based approaches applied to this field. Once the current status in both areas is reviewed, authors purpose the use and creation of an e-Procurement index to evaluate the quality of service of procurement systems. In this light the Analytical Hierarchy Process (AHP) method is used to set up an initial weight for each indicator in the index and to perform a first comparison between traditional and semantic-based approaches. Finally some discussion, conclusions and future challenges are also outlined.     

Vessel Inspection: A Micro-Aerial Vehicle-based Approach

Vessel maintenance entails periodic visual inspections of the internal and external parts of the hull in order to detect the typical defective situations affecting metallic structures, such as coating breakdown, corrosion, cracks, etc. The main goal of project MINOAS is the automation of the inspection process, currently undertaken by human surveyors, by means of a fleet of robotic agents. This paper overviews an approach to the inspection problem based on an autonomous Micro Aerial Vehicle (MAV) which, as part of this fleet, is in charge of regularly supplying images that can teleport the surveyor from a base station to the areas of the hull to be inspected. The control software approach adopted for the MAV is fully described, with a special emphasis on the self-localization capabilities of the vehicle. Experimental results showing the suitability of the platform to the application are as well reported and discussed.     

2-Layer Right Angle Crossing Drawings

A 2-layer drawing represents a bipartite graph where each vertex is a point on one of two parallel lines, no two vertices on the same line are adjacent, and the edges are straight-line segments. In this paper we study 2-layer drawings where any two crossing edges meet at right angle. We characterize the graphs that admit this type of drawing, provide linear-time testing and embedding algorithms, and present a polynomial-time crossing minimization technique. Also, for a given graph G and a constant k, we prove that it is $\mathcal{NP}$ -complete to decide whether G contains a subgraph of at least k edges having a 2-layer drawing with right angle crossings.     

Changes in vitro of the electrolyte content and erythrocyte volume of the venous blood of patients with chronic pneumopathy subjected to tonometry in oxygen]

As previously observed in vivo, statistically significant variations characterized by increase in chlorine and diminution in sodium, associated with an increase in red cell volume, have been noted in vitro in samples of venous blood taken from patients undergoing tonometry under oxygen. These variations appear to be independent of the basic concentration of chlorine and do not occur if the blood samples are incubated with theophylline at the same time. These results confirm the hypothesis of a "non respiratory" plasmatic acidifying effect of oxygen therapy inhibited by the antiphosphodiesterasic action of theophylline.     

Wavelet analysis of short harmonics generated in presence of a two colour laser field

Abstract

The Morlet wavelet spectrum of the radiation emitted by a two level atom in presence of two laser pulses with very close frequency is obtained. The wavelet spectrum gives information on the time evolution of the full spectrum and of a particular line. The beating condition stimulates the atom to emit pulses of harmonics with duration of the order of a few optical cycles of the pumping radiation. Pulse trains of 3 optical cycles (FWHM) are observed.     

Protective effect of fresh and processed Jalapeño and Serrano peppers against food lipid and human LDL cholesterol oxidation

The potential of fresh and processed Jalapeño and Serrano pepper extracts for the control of lipid oxidation in several systems was investigated. The assays used included β-carotene/linoleate model system, striped corn oil, ground pork meat and Cu(II)-induced oxidation of human low-density lipoprotein (LDL). The results showed that all extracts were effective in at least one system, although their potency varied. Extracts of smoked Jalapeño were particularly effective. The lipid-protective effect of the extracts was mainly due to the presence of phenolic compounds, but other phytochemicals, such as chlorophylls were also involved.