Modified multi-wavelength optical orthogonal code for spectral efficiency improvement in two-dimensional optical CDMA system

Classical multi-wavelength optical orthogonal code (MWOOC) constructions impose several conditions on the code parameters. These limit the optical code division multiple access (OCDMA) system potentialities in terms of performance and practical implementation. A modified MWOOC construction is used to overcome these limitations. Indeed, this method permits the design of 2D codes with a low temporal code length value and a low number of wavelengths. Considering a multi-user receiver named parallel interference cancellation, the number of users and the data rate per user the system can provide for a low bit error rate value are evaluated. For a given performance, it is shown that the spectral efficiency using the modified MWOOC is significantly improved. Thus, the simplicity of the modified code design and the spectral efficiency increase constitute an advantage for practical implementation of OCDMA network.     

Mechanical characterization and modeling of the deformation and failure of the highly crosslinked RTM6 epoxy resin

The nonlinear deformation and fracture of RTM6 epoxy resin is characterized as a function of strain rate and temperature under various loading conditions involving uniaxial tension, notched tension, uniaxial compression, torsion, and shear. The parameters of the hardening law depend on the strain-rate and temperature. The pressure-dependency and hardening law, as well as four different phenomenological failure criteria, are identified using a subset of the experimental results. Detailed fractography analysis provides insight into the competition between shear yielding and maximum principal stress driven brittle failure. The constitutive model and a stress-triaxiality dependent effective plastic strain based failure criterion are readily introduced in the standard version of Abaqus, without the need for coding user subroutines, and can thus be directly used as an input in multi-scale modeling of fibre-reinforced composite material. The model is successfully validated against data not used for the identification and through the full simulation of the crack propagation process in the V-notched beam shear test.     

A mass spectrometric strategy for profiling glycoproteinoses, Pompe disease, and sialic acid storage diseases

Glycoproteinoses, Pompe disease, and sialic acid storage diseases are characterized by a massive accumulation of unprocessed oligosaccharides and/or glycoconjugates in urine. The identification of these glycocompounds is essential for a proper diagnosis. In this study, we investigated the potential of MALDI‐TOF‐MS to identify glycocompounds present in urine from patients with different inborn errors of glycan metabolism. Urinary glycocompounds were permethylated, and analyzed using GC‐MS and MALDI‐TOF‐MS. In order to confirm tentative assignments, a second aliquot of urine was purified on a C18 Sep‐Pak cartridge and glycocompounds were desalted on a column of nonporous graphitized carbon. The glycocompounds were then sequentially on‐plate digested using an array of exoglycosidases. A range of disease‐specific oligosaccharides as well as glycopeptides was identified for all oligosacchariduria models. In addition, free sialic acid accumulated in urine from a patient suffering from French‐type sialuria, has been detected by a GC‐MS approach, which could be applied to other sialic acid storage diseases. This procedure is simple, and can be performed in few simple steps in less than 24 h. This current method can be applied for newborn screening for other inherited metabolic diseases as well as for assessing treatments in clinical trials.     

Structural analysis of oligosaccharide-alditols released by reductive beta-elimination from oviducal mucins of Bufo bufo: characterization of the carbohydrate sequence Gal(alpha1-3)GalNAc(alpha1-3)[Fuc(alpha1-2)]Gal

We report the isolation and extensive analysis of highly polymorphic MHC class I genes from sharks (Triakis scyllia), which belong to the most primitive vertebrate group with jaws, the cartilaginous fish. Predicted complete peptide-binding domains showed retention of the critical amino acid residues that would interact with antigenic peptide termini and revealed extensive allelic polymorphisms comparable to those of classic human MHC class I molecules. Mosaic structures were apparent in these domains, suggesting recombinational mechanisms to create allelic diversity. The present study demonstrates the establishment of the basic strategy for antigen-presentation employed by MHC class I molecules and documents complete divergence of two polymorphic MHC classes at a phylogenetically primitive stage of vertebrate evolution.     

A Transparent Membrane for Active Noise Cancelation

A method for active noise cancelation that uses an optically transparent membrane is described. The membrane consists of a prestretched hydrophobic elastomer, attached to a rigid frame and sandwiched between two hydrogels swollen with an aqueous solution of salt. The elastomer functions as a dielectric, and the hydrogel functions as an ionic conductor. When the two hydrogels are subjected to a sinusoidal voltage, the membrane generates sound. A linear model for the reflection, transmission, and generation of sound by the membrane in an impedance tube is presented and validated. Active noise cancelation is demonstrated using the linear model and feedforward control. Compared to passive sound absorption, the sound transmission loss across the membrane is improved with active control from an average value of 7 dB to an average value of 16 dB. The transparent membrane may be used to cancel noises through a window, while maintaining its transparency.     

Synthesis and characterization of poly(aminobismaleimide)s obtained from solvent‐free mixtures

A series of eight poly(aminobismaleimide)s containing aromatic units have been synthesized from a one‐step nucleophilic addition reaction between diamine and bismaleimide, without exogeneous solvent, to provide encapsulant withstanding high temperature suitable for power electronics. To have a homogeneous medium at room temperature, the solid aromatic diamines are first mixed with different liquid aliphatic ones, and then mixed with bismaleimide. The syntheses were then carried out at 175 °C for 15 min. Thus, according to their composition, these obtained thermosetting resins are characterized by a relaxation temperature between 98 and 190 °C and a coefficient of thermal expansion between 20 and 150 ppm/K. All material surfaces are hydrophobic and their moisture uptake is lower than 2–3 wt %. Finally, as expected, the substitution of a part of the aliphatic diamine by an aromatic one improves the thermal stability under air atmosphere of the resulting materials (T_d = 280–300 °C increased to T_d = 315–340 °C). Their use as power module encapsulant can therefore be considered. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46105.     

Shape optimal design and free mesh generation

The concept of structural optimization was introduced in the early sixties. It was at that time that Professor Schmit, from Los Angeles, California University, suggested a combination of structural analysis by finite element and optimization methods (Schmit 1960).At present, the use of optimization methods is generally well understood. The capabilities (and limitations) of these methods are known and some industrial softwares exist. One of these is SAMCEF which can be applied to design of thin-walled structures or to shape optimization. The techniques used for the solution of large scale problems are presented in this paper. A summary of the main difficulties involved in shape optimization is also given. Several industrial problems are solved to illustrate the proposed concepts.     

Structural shakedown analysis by dual finite-element formulations

Starting from Melan's and Koiter's well-known theorems, the present paper establishes the lower and upper bound theorems for the shakedown load factor α, corresponding to a given load domain. In the case of a linear (or linearized) plastic condition, this leads to simple dual formulations enabling one to compute dual bounds for complex structures by means of finite-element and linear mathematical-programming techniques.     

Gallium nitride MEMS resonators: how residual stress impacts design and performances

Microsystem Technologies - Starting from Gallium Nitride epitaxially grown on silicon, pre-stressed micro-resonators with integrated piezoelectric transducers have been designed, fabricated, and...