Modelling mechanical properties of spruce and Douglas fir timber by means of X-ray and grain angle measurements for strength grading purpose

This study proposes a model using data from a scanner (X-ray and grain angle measurements) to perform strength grading. The research also includes global measurements of modulus of elasticity (obtained by vibrations and ultrasound methods), static bending stiffness and bending strength of 805 boards of Douglas fir and 437 boards of spruce. This model can be used in an industrial context since it requires low computational time. The results of this study show that the developed model gives better results than the global non-destructive measurements of the elastic modulus commonly used in the industry. It also shows that this improvement is particularly higher in the case of Douglas fir than for spruce. The comparison has been made on both the quality of the mechanical properties assessment and on the improvement of the grading process according to the European standards by using different index.     

GC/MS profiling of gamma-hydroxybutyrate and precursors in various animal tissues using automatic solid-phase extraction. Preliminary investigations of its potential interest in postmortem interval determination

To quantify gamma-hydroxybutyrate (GHB) and its physiological metabolites, gamma-aminobutyric acid (GABA), 1,4-butanediol (1,4-BD), and gamma-butyrolactone (GBL) in various animal tissues (kidney, muscle, heart, liver, blood, brain cortex, thalamus, hypothalamus, hippocampus, or pons), an original gas chromatographic/mass spectrometric method with a automated solid-phase extraction by Oasis MCX cartridges on a Gilson Aspec Xli was developed. Using such apparatus allowed the limit of detection (LOD) of target compounds to be significantly lowered (LOD: 0.027, 0.025, and 5.7 microg/mL for GHB, 1,4-BD, and GABA, respectively, in 200 microL or microg of sample). After validation of each analytical step, the satisfactory performances of the apparatus in conjunction with the rapidity and ease of the extraction step make it suitable for simultaneous assay of GHB, 1,4-BD, GBL, and GABA. The method was used to test the correlation between GHB levels in tissues obtained at different times after death of male Sprague-Dawley rats and the postmortem interval. Preliminary results show a linear increase of GHB levels in relation to time of death in thoracic blood and central nervous system of animals kept at 15 and 20 degrees C.     

Magnitude and direction of motion with speckle correlation and the optical fractional Fourier transform

The optical fractional Fourier transform (OFRT) in combination with speckle photography has previously been used to measure the magnitude of surface tilting and translation. Previous OFRT techniques used to determine motion have not been able to discern the direction of the tilt and translation. A simple new approach involving use of correlation is presented to overcome this limitation. Controlled variation of the minimum resolution and dynamical range of measurement is demonstrated. It is then experimentally confirmed that if a rigid body's motion is captured by two OFRT systems of different orders, the direction and magnitude of both the tilting and the in-plane translation motion of the body can be independently determined without a priori knowledge. The experimental results confirm the validity of previous theoretical predictions.     

Proposition of a New Severity Analysis Based on ‘Shake’ Detection: Example of the Vatry Airport Tarmac

In packaging science, the study of transport is important in determining the viability of a package/product pair. Many load breaks occur (e.g. handling and storage) along a supply chain. Transport also generates various physical stresses (e.g. shocks, shakes and vibrations). These physical phenomena can be recorded using a variety of customized sensors (e.g. tri‐axial accelerometers, temperature sensors and pressure sensors). This study focuses on a transport phase that has not been studied in depth to date. Transportation operations on tarmacs include many handling and transportation machines, which are characterized by typical constraints that are often more stringent than airlift phase constraints. For comparison, acceleration distributions were estimated and analysed for the tarmac phase and road phase. Severity indicators were calculated based on existing methods. The second part of this study addresses the study of shakes. The shake distributions at 90 and 95% were another indicator of the shakes' severity and probability of occurrence. These elements allow us to characterize the impact of the tarmac area during air transport.     

Kinematic calibration of Orthoglide-type mechanisms from observation of parallel leg motions

The paper proposes a new calibration method for parallel manipulators that allows efficient identification of the joint offsets using observations of the manipulator leg parallelism with respect to the base surface. The method employs a simple and low-cost measuring system, which evaluates deviation of the leg location during motions that are assumed to preserve the leg parallelism for the nominal values of the manipulator parameters. Using the measured deviations, the developed algorithm estimates the joint offsets that are treated as the most essential parameters to be identified. The validity of the proposed calibration method and efficiency of the developed numerical algorithms are confirmed by experimental results. The sensitivity of the measurement methods and the calibration accuracy are also studied.     

Coherent Dynamics of Localized Spins in an Inhomogeneous Magnetic Field

We studied the influence of the inhomogeneity of fringe fields originating from nanostructured ferromagnets on the coherent dynamics of localized Mn²⁺ spins in a (Zn,Cd,Mn)Se/ZnSe quantum well by time-resolved Kerr rotation. By studying hybrid systems with different geometry, we demonstrate that the spatially inhomogeneous fringe field results in two main consequences for the localized spin system: First, a temporal variation of the ensemble precession frequency is obtained, and second, a reduced ensemble spin dephasing time T ₂^* is observed in comparison to an unstructured reference area of the sample.     

First-principles study of nickel-silicides ordered phases

We present a study of nickel-silicides ordered alloys by means of first-principles calculations. Emphasis was put on the phases (low and high temperatures) identified in the binary phase diagram, namely: Ni₃Si-β₁, -β₂, and -β₃, Ni₃₁Si₁₂-γ, Ni₂Si-δ, -θ, Ni₃Si₂-?, NiSi-MnP and NiSi₂-α. In addition, some common structures are computed for information: L1₂, D0₃ and D0₂₂. The simulations reproduce with a high accuracy lattice parameters and formation energies of main experimental structures, except for β₂ and β₃. Our results clarify the crystallographic nature of the γ structure, and the comparison of experimental Raman spectra and vibrational calculations will help experimentalists to identify without ambiguity NiSi₃ structures.     

Numerical modelling of interfacial soil erosion with viscous incompressible flows

The aim of this study is to develop a numerical model for simulating surface erosion occurring at a fluid/soil interface subject to a flow process. Balance equations with jump relations are used. A penalization procedure including a fictitious domain method is used to compute the Stokes flow around obstacles, in order to avoid body-fitted unstructured meshes and instead use fast and efficient finite volume approximations on Cartesian meshes. The evolution of the water/soil interface is described by using a level set function. The ability of the model to predict the interfacial erosion of soils is confirmed by several numerical simulations.     

Sizing optimization of a stand-alone street lighting system powered by a hybrid system using fuel cell,PV and battery

Currently commercialised stand-alone street lighting systems based on the classical configuration coupling photovoltaic cells (PV) and battery cannot work all the year round in regions that are far from the equator. To improve the classical system, a hybrid system coupling a PV, a battery and a fuel cell is proposed. However, the sizing method of hybrid systems is a key issue in obtaining the cheapest system. To optimise the system, an original time-saving method is applied. Two optimization methods are used: first the genetic algorithms, then the simplex algorithms. A simulation model is used to evaluate the validity of the different hybrid configurations. After presenting the problem of stand-alone street lighting, the optimization methodology and the simulation model are detailed. Finally, an optimal configuration is obtained and shows that a 60 W street light would cost 7150€ with a lifetime of 25 years. The optimised parameters are also given and analysed.