Higgs production in gluon fusion at next-to-next-to-leading order QCD for finite top mass

The inclusive Higgs production cross section from gluon fusion is calculated through NNLO QCD, including its top quark mass dependence. This is achieved through a matching of the 1/mtop expansion of the partonic cross sections to the exact large s-hat limits which are derived from k_T-factorization. The accuracy of this procedure is estimated to be better than 1% for the hadronic cross section. The final result is shown to be within 1% of the commonly used effective theory approach, thus confirming earlier findings.Comment: 28 pages, 14 figure

Galerkin's method revisited and corrected in the problem of Jaworski and Dowell

This paper revisits the problem first studied by Jaworski and Dowell, namely, the free vibration of multi-step beams. Previous authors utilized approximate method of Ritz as well as the finite element method with attendant comparison with the experimental results. This study provides the exact solution for the Jaworski and Dowell problem in terms of Krylov-Duncan functions. Additionally, the Galerkin method is applied and contrasted with the exact solution. It is shown that the straightforward implementation of the Galerkin method, as it is usually performed in the literature, does not lead to results obtained by Jaworski and Dowell using the Ritz method. Moreover, the straightforward application of the Galerkin method does not tend to the results obtained by either exact solution or experiments. A modification of the Galerkin method is proposed by introducing generalized functions to describe both mass and stiffness of the stepped beam. Specifically, the unit step function, Dirac's delta function and the doublet function, are utilized for this purpose. With this modification, the Galerkin method yields results coinciding with those derived by the Ritz method, and turn out to be in close vicinity with those produced by the exact solution as well as experiments.(c) 2021 Elsevier Ltd. All rights reserved

Data-driven modeling of long temperature time-series to capture the thermal behavior of bridges for SHM purposes

Bridges experience complex heat propagation phenomena that are governed by external thermal loads, such as solar radiation and air convection, as well as internal factors, such as thermal inertia and geometrical properties of the various components. This dynamics produces internal temperature distributions which cause changes in some measurable structural responses that often surpass those produced by any other load acting on the structure or by the insurgence or growth of damage. This article advocates the use of regression models that are capable of capturing the dynamics buried within long sequences of temperature measurements and of relating that to some measured structural response, such as strain as in the test structure used in this study. Two such models are proposed, namely the multiple linear regression (MLR) and a deep learning (DL) method based on one-dimensional causal dilated convolutional neural networks, and their ability to predict strain is evaluated in terms of the coefficient of determination R 2. Simple linear regression (LR), which only uses a single temperature reading to predict the structural response, is also tested and used as a benchmark. It is shown that both MLR and the DL method largely outperform LR, with the DL method providing the best results overall, though at a higher computational cost. These findings confirm the need to consider the evolution of temperature if one wishes to setup a temperature-based data-driven strategy for the SHM of large structures such as bridges, an example of which is given and discussed towards the end of the article.</p

Surface wave non-reciprocity via time-modulated metamaterials

We investigate how Rayleigh waves interact with time-modulated resonators located on the free surface of a semi-infinite elastic medium. We begin by studying the dynamics of a single resonator with time-modulated stiffness, we evaluate the accuracy of an analytical approximation of the resonator response and identify the parameter ranges in which its behavior remains stable. Then, we develop an analytical model to describe the interaction between surface waves and an array of resonators with spatio-temporally modulated stiffness. By combining our analytical models with full-scale numerical simulations, we demonstrate that spatio-temporal stiffness modulation of this elastic metasurface leads to the emergence of non-reciprocal features in the Rayleigh wave spectrum. Specifically, we show how the frequency content of a propagating signal can be filtered and converted when traveling through the modulated medium, and illustrate how surface-to-bulk wave conversion plays a role in these phenomena. Throughout this article, we indicate bounds of modulation parameters for which our theory is reliable, thus providing guidelines for future experimental studies on the topic

Damage identification in various types of composite plates using guided waves excited by a piezoelectric transducer and measured by a laser vibrometer

Composite materials are widely used in the industry, and the interest of this material is growing rapidly, due to its light weight, strength and various other desired mechanical properties. However, composite materials are prone to production defects and other defects originated during exploitation, which may jeopardize the safety of such a structure. Thus, non-destructive evaluation methods that are material-independent and suitable for a wide range of defects identification are needed. In this paper, a technique for damage characterization in composite plates is proposed. In the presented non-destructive testing method, guided waves are excited by a piezoelectric transducer, attached to tested specimens, and measured by a scanning laser Doppler vibrometer in a dense grid of points. By means of signal processing, irregularities in wavefield images caused by any material defects are extracted and used for damage characterization. The effectiveness of the proposed technique is validated on four different composite panels: Carbon fiber-reinforced polymer, glass fiber-reinforced polymer, composite reinforced by randomly-oriented short glass fibers and aluminum-honeycomb core sandwich composite. Obtained results confirm its versatility and efficacy in damage characterization in various types of composite plates

Molecular Identification and Management of Rhizoctonia Fragariae the Pathogen of Black Root Rot of Strawberry Plant

Strawberry plants are susceptible to a large number of pests and diseases and this can affect the quality and yield value of the fruit. Black root rot is an important disease of strawberry caused by a complex of fungi including Rhizoctonia. The most recognizable species of Rhizoctonia are R. solani and R. fragariae which are multinucleate and binucleate species, respectively. This work is aimed to isolate, identify and control the strawberry root rot caused by R. fragariae. Infected strawberry samples were collected from Erbil, Slemani, Duhok and Garmiyan Provinces. The identification of isolated fungi was achieved by using traditional methods along with molecular methods using polymerase chain reaction (PCR). In the later method, specific primers were designed and used to identify Rhizoctonia species. Several disease management options, including biological by using two species of Trichoderma, and chemical methods using Pristine fungicide, were also investigated. Sampling of strawberry plants revealed that the disease is prevalent in Kurdistan region and the isolated fungi, R. solani, Rhizoctonia sp., and R. fragariae, were pathogens of the disease causing crown and root rot of strawberry. PCR amplification was confirmed the identification of the species of Rhizoctonia. The results of control methods revealed that the most effective treatments were achieved using the fungicide followed by the use of the combination of T. harzianum and T. viride

Comparison of numerical models for Acoustic Emission propagation

Abstract Acoustic Emissions (AE) are at the basis of extremely accurate and reliable monitoring systems. Within the SmartBench project, data regarding structural health of components are gathered in a database in order to make safety integrated, operative and smart. An accurate modelling of wave propagation is a necessary requirement for a proper design of sensor networks as well as for data interpretation. Numerical simulations of the transient behavior of structural systems are well-established in this field but, on the minus side, they are very expensive in terms of computational time and resources. This paper reports different instances of AE propagation through metallic media. Bulk waves and guided waves are both investigated by means of 2D and 3D models and resorting to different software. Obtained results are cross-checked and computational times are compared as well. As a last point, High Performance Computing is applied to the case of waves simulation in order to get a significant reduction of the required computational time

Proceedings of the workshop "Standard Model at the LHC" University College London 30 March - 1 April 2009

Proceedings from a 3-day discussion on Standard Model discoveries with the first LHC dataComment: 9 contributions to the proceedings of the LHC Standard Model worksho

Synthesis and biological evaluation of new natural phenolic (2E,4E,6E)-Octa-2,4,6-trienoic esters

In the present study the esterification of the OH groups of resveratrol, caffeic acid, ferulic acid, and -sitosterol with an antioxidant polyconjugated fatty acid, (2E,4E,6E)-octa-2,4,6-trienoic acid, was achieved. As the selective esterification of OH groups of natural compounds can affect their biological activity, a selective esterification of resveratrol and caffeic acid was performed by an enzymatic approach. The new resulting compounds were characterized spectroscopically (FT-IR, NMR mono, and bidimensional techniques); when necessary the experimental data were integrated by quantum chemical calculations. The antioxidant, anti-inflammatory and proliferative activity was evaluated. The good results encourage the use of these molecules as antioxidant and/or anti-inflammatory agents in dermocosmetic application

Development of a 3D multispectral scanner

In this paper, a new technique of scanning is proposed. It is based on a stereoscopic set composed of a structured light projector and a multispectral camera. Such a set can give the 3D information of a point like a scanner but can add accurate information about the spectral reflectance of this point. This set must be calibrated before using it. It is done by two steps: the first one is the spectral characterization of the couple illuminant and camera ; the second allows geometrically calibrating the complete set. Afterwards, the image acquisition can begin. A first multispectral image of the scene is obtained without projection of structured light. Then, with a LCD projector, a luminous line scans the scene. For each line, a grey level image is acquired. The use of the geometrical calibration parameters allows the processing of the three-dimensional coordinates of the lighted points on the scene. Moreover, and it is the main goal of the proposed system, a spectral reflectance can be associated to the built points. This spectral data comes, on one hand, from the already-done spectral characterization, and, on the other hand, from the first multispectral image acquired without projection of structured light. By comparing the results issued from such a system and those from a system composed of a color camera or a color scanner, we notice that the spectrum associated to the three-dimensional points brings much more informative data than only three color components: for example, since the spectral reflectance is independent of the light used during the acquisition, the 3D scene can be easily simulated under any illuminant. This kind of simulations finds a great interest in several multimedia applications such as 3D objects visualization for virtual museums.Dans cet article, une nouvelle technique de scanning est proposée. Elle est basée sur un système stéréoscopique composé d’un projecteur de lumière structurée et d’une caméra multispectrale. Un tel système offre la possibilité de donner l’information 3D d’un point comme pour un scanner classique mais également de fournir une information précise sur le spectre de réflectance de ce point. Avant utilisation, il est nécessaire de calibrer l’ensemble. Le calibrage se déroule en deux étapes : la première d’entre elles consiste à caractériser la réponse spectrale de l’ensemble illuminant et caméra, la seconde permet de le calibrer géométriquement. A ce stade, l’analyse de la scène à reconstruire consiste, en premier lieu, en l’acquisition d’une unique image multispectrale de la scène sans projection de motif caractéristique. Ensuite, à l’aide d’un projecteur LCD, une ligne de lumière est projetée en balayage sur la scène. Pour chaque projection de ligne, une image en niveaux de gris est acquise. L’utilisation des paramètres de calibrage géométrique permet de remonter aux coordonnées tridimensionnelles des points illuminés de la scène. De plus, et c’est ici que réside l’apport principal du système proposé, un spectre de réflectance est associé à chacun des points reconstruits. Cette information spectrale provient d’une part, de la caractérisation spectrale préalablement effectuée et d’autre part, de la première image multispectrale acquise sans projection de lumière structurée. Si l’on compare les résultats obtenus avec un tel système et ceux issus d’un système composé d’une caméra couleur ou d’un scanner couleur, on remarque que le spectre associé aux points tridimensionnels apporte une information considérablement plus riche qu’un simple triplet de composantes chromatiques : par exemple, l’information spectrale étant indépendante de l’illuminant utilisé pendant l’acquisition, la scène 3D reconstruite peut être aisément simulée sous un illuminant quelconque. Ce genre de simulations trouve son intérêt dans des applications multimédias de type visualisation d’objets 3D pour des musées virtuels