A study on interlaminar behavior of carbon/epoxy laminated curved beams by use of acoustic emission

The interlaminar tensile strength of carbon/epoxy laminated curved beams with variable thickness and through-the-thickness tufted reinforcement is studied experimentally by means of a four-point-bending test in accordance with ASTM D6415. These tests are monitored by the acoustic emission (AE) technique in order to gain deeper knowledge of the delamination onset and post-failure behavior. The results show that AE technique has proven to perform well when identifying delamination onset and its evolution after failure. In addition to this, AE has demonstrated to be an appropriate tool to assess the manufacturing quality of the carbon/epoxy laminated curved-beam, once the right pattern has previously been established

Comparative Study of Vibration Response in Steel and Braided-Carbon-Fiber Bicycle Handlebars: A Numerical-Experimental Approach with Various Sensors

\ua9 2024 by the authors. The comfort and safety of a cyclist are directly influenced by the vibrational behavior of the handlebar. Hence, the objective of this article is to comparatively assess the vibrational characteristics of two bicycle handlebars: one made of steel and the other made of braided composite material. The transmissibility function represents the relationship between the excitation applied to both handlebars through their stems and the corresponding response in the handle area, which was experimentally obtained by applying a random vibrating signal (constant amplitude of 0.01 g2/Hz) using a shaker. This signal was applied in a frequency range between 100 Hz and 1200 Hz, and the response was measured at one of the two cantilevered ends of the handlebar. Different sensors, including a laser vibrometer and a control accelerometer in the shaker, were utilized. The transmissibility, natural frequencies and damping functions were obtained. Subsequently, another experimental analysis was carried out with the instrumented handlebars mounted on a bicycle, placing three accelerometers and a GPS meter and traveling through a real test circuit, with a rough surface, speed bumps and areas with shaped warning bands. Power Spectral Density (PSD) curves were obtained for the steel and carbon-fiber-composite handlebars in order to quantify the signal intensity. Finally, a fatigue analysis was carried out in order to evaluate the expected life of both handlebars under the experimentally applied load, which is considered the reference cycle. This study offers a comparative analysis of the vibration behavior exhibited by steel and carbon-fiber-composite bicycle handlebars under experimentally applied load. In conclusion, data on natural frequencies, damping functions and fatigue life expectancy for both handlebar materials were obtained. Our study provides valuable insights into the vibrational behavior and performance characteristics of steel and carbon-fiber-composite bicycle handlebars, contributing to the understanding of their comfort and safety implications for cyclists

Analysis of the MPEG-2 Encoding Algorithm with ROSA1 1This work has been supported by the CICYT project “Performance Evaluation of Distributed Systems”, TIC2000-0701-C02-02.

AbstractThe authors present both the specification and a performance analysis of the MPEG2 algorithm for video encoding, by using the Stochastic Process Algebra ROSA. This process algebra is a very general framework for describing and analyzing more complex Real Time Systems than the one presented. Some interesting results about the temporal behaviour of the algorithm and an immediate estimation of benefits when having a twin-processors platform have been obtained

Development of a fatigue life prediction methodology for welded steel semi-trailer components based on a new criterion

This paper presents a procedure developed to predict the fatigue life in components made of steel, based on the mechanical properties of the base material and Thermally Affected Zones (TAZs) owing to welding. The fatigue life cycles of the studied components are obtained based on a certain survival probability provided by a Weibull distribution. This procedure is thought to be applied on semi-trailer components, and therefore it is proposed for the steels that are typically used in its manufacturing. A criterion for the adjustment of the exponent and the stress stroke of the fatigue life curve in welded joints is proposed in which the parameters that define the alternating stress versus the number of cycles to failure (S-N) curve are obtained exclusively from the ratio between the base material yield stress of a given steel and the strength of its Thermally Affected Zone. This procedure is especially useful for steels that do not have a complete characterization of their fatigue parameters. These developments are implemented in a subroutine that can be applied in commercial codes based on Finite Element Method (FEM) to obtain a fatigue life prediction. Finally, a numerical-experimental validation of the developed procedure is carried out by means of a semi-trailer axle bracing support fatigue analysis

Effects of A -site ordering on the Mn local structure and polar phases of R Ba Mn 2 O 6 ( R = La , Nd, Sm, and Y)

We have investigated the temperature dependence of the Mn local structure in A-site ordered RBaMn2O6 (R = La, Nd, Sm, and Y) perovskites, in parallel with their disordered counterparts, R0.5Ba0.5MnO3, by means of x-ray emission (XES) and x-ray absorption spectroscopy (XAS) The end member LaBaMn2O6 shows a nearly regular MnO6 octahedron independent of temperature. With decreasing the R ionic radius in the ordered samples, the XAS results indicate that a local distortion develops in the MnO6 octahedron at the low-temperature charge-localized and polar phases. For NdBaMn2O6, this local distortion is tiny, indicating the absence of charge segregation at the Mn site. This is followed by a bigger local distortion anticipated for SmBaMn2O6 in its respective charge-localized and polar phase and finally, the biggest local distortion for the smallest A-site cation ordered compound, YBaMn2O6, for which it even persists above the polar charge-localization transition temperatures. The high-resolution XAS spectra confirm the presence of charge segregation between two nonequivalent Mn sites in the low-temperature polar phase of Sm and Y ordered samples. Thus, our XAS study suggests a displacive mechanism for the charge-localization and polar transitions in the Nd and Sm ordered samples while a combination of displacive and order-disorder contributions is revealed for YBaMn2O6. Besides, calorimetric measurements confirm the combination of the two mechanisms, order-disorder and displacive, for the ordered Sm and Y compounds. On the other hand, the A-site disordered R0.5Ba0.5MnO3 samples with R cations smaller than Nd present a significant static (temperature-independent) local disorder, which explains why polar charge-localization transitions are not developed in these samples. Finally, we correlate our results about the Mn local structure and character of the transitions with the macroscopic magnetic and electric behavior of both A-site ordered and disordered compounds

A hybrid Quantum proposal to deal with 3-SAT problem

Going as far as possible at SAT problem solving is the main aim of our work. For this sake we have made use of quantum computing from its two, on practice, main models of computation. They have required some reformulations over the former statement of 3-SAT problem in order to accomplish the requirements of both techniques. This paper presents and describes a hybrid quantum computing strategy for solving 3-SAT problems. The performance of this approximation has been tested over a set of representative scenarios when dealing with 3-SAT from the quantum computing perspective.Comment: 25 pages, 21 figures, 4 table

First modern human settlement recorded in the Iberian hinterland occurred during Heinrich Stadial 2 within harsh environmental conditions

As the south-westernmost region of Europe, the Iberian Peninsula stands as a key area for understanding the process of modern human dispersal into Eurasia. However, the precise timing, ecological setting and cultural context of this process remains controversial concerning its spatiotemporal distribution within the different regions of the peninsula. While traditional models assumed that the whole Iberian hinterland was avoided by modern humans due to ecological factors until the retreat of the Last Glacial Maximum, recent research has demonstrated that hunter-gatherers entered the Iberian interior at least during Solutrean times. We provide a multi-proxy geoarchaeological, chronometric and paleoecological study on human–environment interactions based on the key site of Peña Capón (Guadalajara, Spain). Results show (1) that this site hosts the oldest modern human presence recorded to date in central Iberia, associated to pre-Solutrean cultural traditions around 26, 000 years ago, and (2) that this presence occurred during Heinrich Stadial 2 within harsh environmental conditions. These findings demonstrate that this area of the Iberian hinterland was recurrently occupied regardless of climate and environmental variability, thus challenging the widely accepted hypothesis that ecological risk hampered the human settlement of the Iberian interior highlands since the first arrival of modern humans to Southwest Europe. © 2021, The Author(s)

Characterization of new regulatory elements within the Drosophila bithorax complex

The homeotic Abdominal-B (Abd-B) gene expression depends on a modular cis-regulatory region divided into discrete functional domains (iab) that control the expression of the gene in a particular segment of the fly. These domains contain regulatory elements implicated in both initiation and maintenance of homeotic gene expression and elements that separate the different domains. In this paper we have performed an extensive analysis of the iab-6 regulatory region, which regulates Abd-B expression at abdominal segment A6 (PS11), and we have characterized two new polycomb response elements (PREs) within this domain. We report that PREs at Abd-B cis-regulatory domains present a particular chromatin structure which is nuclease accessible all along Drosophila development and both in active and repressed states. We also show that one of these regions contains a dCTCF and CP190 dependent activity in transgenic enhancer-blocking assays, suggesting that it corresponds to the Fab-6 boundary element of the Drosophila bithorax complex

First modern human settlement recorded in the Iberian hinterland occurred during Heinrich Stadial 2 within harsh environmental conditions

As the south-westernmost region of Europe, the Iberian Peninsula stands as a key area for understanding the process of modern human dispersal into Eurasia. However, the precise timing, ecological setting and cultural context of this process remains controversial concerning its spatiotemporal distribution within the different regions of the peninsula. While traditional models assumed that the whole Iberian hinterland was avoided by modern humans due to ecological factors until the retreat of the Last Glacial Maximum, recent research has demonstrated that hunter-gatherers entered the Iberian interior at least during Solutrean times. We provide a multi-proxy geoarchaeological, chronometric and paleoecological study on human?environment interactions based on the key site of Peña Capón (Guadalajara, Spain). Results show (1) that this site hosts the oldest modern human presence recorded to date in central Iberia, associated to pre-Solutrean cultural traditions around 26,000 years ago, and (2) that this presence occurred during Heinrich Stadial 2 within harsh environmental conditions. These findings demonstrate that this area of the Iberian hinterland was recurrently occupied regardless of climate and environmental variability, thus challenging the widely accepted hypothesis that ecological risk hampered the human settlement of the Iberian interior highlands since the first arrival of modern humans to Southwest Europe.Tis research was carried out in the context of the ERC MULTIPALEOIBERIA project, funded by the European Research Council (ERC-2018-STG-805478), and the PALEOINTERIOR project, funded by the Spanish Ministry of Science and Innovation (HAR2017-82483-C3-3-P)