Solitary wave solutions and their interactions for fully nonlinear water waves with surface tension in the generalized Serre equations

Some effects of surface tension on fully nonlinear, long, surface water waves are studied by numerical means. The differences between various solitary waves and their interactions in subcritical and supercritical surface tension regimes are presented. Analytical expressions for new peaked traveling wave solutions are presented in the dispersionless case of critical surface tension. Numerical experiments are performed using a high-accurate finite element method based on smooth cubic splines and the four-stage, classical, explicit Runge–Kutta method of order 4.     

On the identification of a high-resolution multi-linear post-necking strain hardening model

The Finite Element Model Updating (FEMU) technique is an inverse method that enables to arrive at a complete solution to the problem of diffuse necking of a thick tensile specimen. Conventionally, FEMU relies on the identification of a phenomenological strain hardening law that inherently limits the accuracy of the method due to the predefined character of the adopted strain hardening law. A high-resolution multi-linear post-necking strain hardening model enables to describe more generically the actual strain hardening behaviour. A numerical concept study is used to scrutinise the identification of such a model using FEMU. It is shown that, unlike progressive identification strategies, a global identification strategy followed by a smoothing operation based on area conservation yields sufficiently accurate results. To study the experimental feasibility, the latter strategy is used to identify the post-necking strain hardening behaviour of a thick S690QL high-strength steel. To this purpose, a notched tensile specimen was loaded up to fracture, while the elongation was measured using Digital Image Correlation (DIC). It is shown that the global identification strategy suffers from experimental noise associated with DIC and the load signal.     

Lab-in-a-tube: ultracompact components for on-chip capture and detection of individual micro-/nanoorganisms

A review of present and future on-chip rolled-up devices, which can be used to develop lab-in-a-tube total analysis systems, is presented. Lab-in-a-tube is the integration of numerous rolled-up components into a single device constituting a microsystem of hundreds/thousands of independent units on a chip, each individually capable of sorting, detecting and analyzing singular organisms. Such a system allows for a scale-down of biosensing systems, while at the same time increasing the data collection through a large, smart array of individual biosensors. A close look at these ultracompact components which have been developed over the past decade is given. Methods for the capture of biomaterial are laid out and progress of cell culturing in three-dimensional scaffolding is detailed. Rolled-up optical sensors based on photoluminescence, optomechanics, optofluidics and metamaterials are presented. Magnetic sensors are introduced as well as electrical components including heating, energy storage and resistor devices.     

Effect of Ag nanoparticle addition and ultrasonic treatment on a stable TiO2 nanofluid

Nanoparticles, when homogeneously dispersed in a base fluid, e.g. water, ethylene glycol etc. are commonly known as nanofluids. Nanofluids have gained attention in the scientific community for their enhanced thermal properties. One of the major problems in using nanofluids as a heat transfer medium for commercial applications is that, in most of the closed circuit industrial cooling processes, the cooling fluid has to be replaced after several cycles of cooling operation because of an increased presence of contaminants. If nanofluids were used as a coolant, it would be very hard to separate the nanoparticles from the waste fluid. The present work is aimed at the separation and recycling of nanoparticles from fluid waste by means of quick settling of titanium dioxide nanoparticles using silver nanoparticles along with ultrasonic treatment. It is observed that with increasing silver concentration and time of ultrasonication, the stability of the dispersion decreases. There is a value for both the silver concentration and ultrasonication time above which the settling time decreases drastically.     

Practical use of variational principles for modeling water waves

This paper describes a method for deriving approximate equations for irrotational water waves. The method is based on a ‘relaxed’ variational principle, i.e., on a Lagrangian involving as many variables as possible. This formulation is particularly suitable for the construction of approximate water wave models, since it allows more freedom while preserving a variational structure. The advantages of this relaxed formulation are illustrated with various examples in shallow and deep waters, as well as arbitrary depths. Using subordinate constraints (e.g., irrotationality or free surface impermeability) in various combinations, several model equations are derived, some being well-known, other being new. The models obtained are studied analytically and exact traveling wave solutions are constructed when possible.     

Generation of diversiform gold nanostructures inspired by honey's components: Growth mechanism, characterization, and shape separation by the centrifugation-assisted sedimentation

The green synthesis of irregular-shaped nanomaterials used for various applications in nanoplasmonics, medicine, and biotechnology creates an economical and environmental challenge. We describe the rapid wet-chemical approach to synthesis of stable and water-soluble gold nanostructues at room temperature. In addition to spherical and road-like nanoparticles, gold decahedra and triangular plates were grown using the one-step synthesis process of HAuCl(4) in the presence of honey, in which main components act as reducing (glucose) and stabilizing (fructose) agents; the mechanism of the process is discussed in details. The requirements for anisotropic phase boundaries for generation of polyhedral gold nanocrystals in solutions are highlighted. The synthesis, morphology, and separation procedure of gold nanoparticles are examined using the techniques of optical spectroscopy, transmission electron microscopy, and atomic force microscopy. We demonstrate that centrifugation can be used for efficient separation of nanoparticles with different shapes from a mixture. It was found that while centrifuging, the spheres sediment at the bottom of the tube, segregating from rods that form a deposit on the side wall, whereas polygons remain in the solution.     

Hydrogen in La2MgNi9D13: the role of magnesium

Reversible hydrogen storage capacity of the La(3-x)Mg(x)Ni(9) alloys, charged by gaseous hydrogen or by electrochemical methods, reaches its maximum at composition La(2)MgNi(9). As (La,Mg)Ni(3-3.5) alloys are the materials used in advanced metal hydride electrodes in Ni-MH batteries, this raises interest in the study of the structure-properties interrelation in the system La(2)MgNi(9)-H(2) (D(2)). In the present work, this system has been investigated by use of in situ synchrotron X-ray and neutron powder diffraction in H(2)/D(2) gas and by performing pressure-composition-temperature measurements. The saturated La(2)MgNi(9)D(13.1) hydride forms via an isotropic expansion and crystallizes with a trigonal unit cell (space group R3m (No.166); a = 5.4151(1) ?; c = 26.584(2) ?; V = 675.10(6) ?(3)). The studied hybrid structure is composed of a stacking of two layers resembling existing intermetallic compounds LaNi(5) (CaCu(5) type) and LaMgNi(4) (Laves type). These are occupied by D to form LaNi(5)D(5.2) and LaMgNi(4)D(7.9). The LaNi(5)D(5.2) slab has a typical structure observed for all reported LaNi(5)-containing hybrid structures of the AB(5) + Laves phase types. However, the Laves type slab LaMgNi(4)D(7.9) is different from the characterized individual LaMgNi(4)D(4.85) hydride. This results from the filling of a greater variety of interstitial sites in the La(2)MgNi(9)D(13)/LaMgNi(4)D(7.9), including MgNi(2), Ni(4), (La/Mg)(2)Ni(2), and (La/Mg)Ni(3), in contrast with individual LaMgNi(4)D(4.85) where only La(2)MgNi(2) and Ni(4) interstitials are occupied. Despite a random distribution of La and Mg in the structure, a local hydrogen ordering takes place with H atoms favoring occupation of two Mg-surrounded sites, triangles MgNi(2) and tetrahedra LaMgNi(2). A directional bonding between Ni, Mg, and hydrogen is observed and is manifested by a formation of the NiH(4) tetrahedra and MgH(6) octahedra, which are connected to each other by sharing H vertexes to form a spatial framework.     

Determination of Levodopa in Pharmaceuticals Using a Disposable Electrochemically Activated Carbon-Paste Electrode by Linear Sweep Voltammetry

A simple disposable electrochemically activated carbon-paste electrode was developed for the determination of levodopa in pharmaceuticals and the optimal conditions for carbon-paste electrode electrochemical activation were studied. The study of the oxidation process of levodopa on the proposed electrode was performed using cyclic voltammetry and the irreversibility of levodopa with a kinetic-controlled current was established. The determination of levodopa is possible in the concentration range of 5–100?µM. The detection and quantification limits were 0.65 and 0.79?µM, respectively. The proposed procedure was satisfactorily applied in the levodopa determination in pharmaceuticals with relative standard deviation 3.4%.     

Polynomial Approximations for Bivariate Aggregate Claims Amount Probability Distributions

A numerical method to compute bivariate probability distributions from their Laplace transforms is presented. The method consists in an orthogonal projection of the probability density function with respect to a probability measure that belongs to a Natural Exponential Family with Quadratic Variance Function (NEF-QVF). A particular link to Lancaster probabilities is highlighted. The procedure allows a quick and accurate calculation of probabilities of interest and does not require strong coding skills. Numerical illustrations and comparisons with other methods are provided. This work is motivated by actuarial applications. We aim at recovering the joint distribution of two aggregate claims amounts associated with two insurance policy portfolios that are closely related, and at computing survival functions for reinsurance losses in presence of two non-proportional reinsurance treaties.