Measurement of thermal radiative and conductive properties of semitransparent materials using a photothermal crenel method

This paper deals with a theoretical and an experimental study allowing the measurement of the radiative and the conductive properties of semitransparent materials. The method consists of applying a crenel heat flux on the front face of a semitransparent sample and recording the temperature at the rear face using an open thermocouple junction.Parameter identification is performed by the minimization of the ordinary least-squares function comparing the measured and the calculated temperatures. This later is obtained from the thermal model describing the heat transfer by conduction and radiation in the medium. This model is built by the thermal quadrupole formalism.Measurements are reported on commercial glasses and plexiglass samples, and the used iterative algorithm is based on the Gauss-Newton method.     

Theoretical and numerical study of Couette-Taylor flow with an axial flow using lattice Boltzmann method

In this study, the numerical models for swirling flows developed by Li et al and Zhou for lattice Boltzmann method (LBM) are chosen. These models were firstly validated using the Couette-Taylor flow between two concentric cylinders simulations. Numerical results showed the efficiency of the Zhou's model. Numerical simulation results using LBM are in good agreement for the steady and unsteady regimes compared to the literature review. In a second step, the Zhou model was then adopted to our study to determine the Couette-Taylor instabilities with an axial flow. Two protocols are tested. The first one (direct protocol) starts with an azimuthal flow without any axial flow (Re = 0). Once the regime is established, an axial flow is then superposed to the Couette-Taylor flow (with a sudden or a progressive manner). The second protocol (inverse protocol) starts with an axial flow at a given Reynolds number (Poiseuille flow). Once the regime is established, an azimuthal flow is the executed (with a sudden or a progressive manner). The effect of various parameters controlling the physical situation is also discussed. The increase of the azimuthal velocity mainly led to the emergence and development of Taylor vortices. Its influence decreases when the axial Reynolds number increases. The relevant result for this study is the change of the critical axial Reynolds number Re_c (total disappearance of instabilities) with both protocols and both manners.     

Production of CoAl and CoAlCr FSMAs and determination of their thermal,microstructure, and magnetic properties

Journal of Thermal Analysis and Calorimetry - In this study, some thermal, mechanical, and magnetic properties of Co86Al14 and Co82Al14Cr4 (at.%) alloys have been investigated. The alloys were...     

Effect of the TiC content on microstructure and thermal properties of Cu–TiC composites prepared by powder metallurgy

Copper matrix with an individual addition of TiC particles was prepared by means of powder metallurgy and hot pressing process, and the effect of TiC addition on microstructure, thermal properties, and electrical conductivity of Cu–TiC composites was investigated. The TiC quantity was changed as 1, 3, 5, 10, and 15 Cu (in mass%), and Cu–TiC powder mixtures were hot-pressed for 4 min at 700 °C under an applied pressure of 50 MPa. Microstructure studies revealed that TiC particles were distributed uniformly in the Cu matrix. Thermal Analysis result showed that there were two exothermic peaks and with rising TiC rate, oxidation amount of Cu composite decreased. With the increasing addition of TiC, hardness of composites changed between 58.6 HV_0.1 and 87.8 HV_0.1. The highest electrical conductivity for Cu–TiC composites was obtained in the Cu-1 mass% TiC composite, with approximately 81.2 % IACS.     

Ground state and phonon spectrum of NiSi2

We have studied structural, electronic, elastic and dynamical properties of NiSi₂ by employing the plane wave pseudopotential method based on density functional theory within the local density approximation. The calculated lattice constant, bulk modulus and first-order pressure derivative of the bulk modulus are reported and compared with earlier available experimental and theoretical calculations. Numerical first-principles calculations of the elastic constants were used to calculate C₁₁, C₁₂ and C₄₄ for NiSi₂. The calculated electronic band structure has been compared with angle-resolved photoemission spectroscopy experimental data along the [100] and [111] symmetry directions. A linear response approach to density functional theory is used to derive the phonon dispersion curves and phonon partial density of states. Atomic displacement patterns for NiSi₂ at the Γ, X and L symmetry points are also presented.     

A Lagrangean-based heuristics for the target covering problem in wireless sensor network

We study the target coverage problem in wireless sensor networks. The problem consists in maximizing the network lifetime by grouping the sensors in disjoint set covers of the targets. A binary integer programing model is formulated to maximize the network lifetime. Since the problem is NP-complete, we provide an iterative approximation based on Lagrangean relaxation and subgradient optimization.     

Corrosion Behavior of Biocompatible Stainless Steels in Physiological Medium for Non‐invasive Diagnosis of Small Fiber Neuropathies Applications

A non‐invasive device based on measurements of electrochemical skin conductance can detect small fiber neuropathy, a sweat gland dysfunction implicated in several diseases. The measurement is related to sweat composition and notably to chloride concentration. To optimize the electrode material, in vitro experiments are performed in mimetic sweat solutions. This work reports on the resistance to pitting corrosion of biocompatible stainless steels (AISI 304L, AISI 430, AISI 430T, D2205) in sweat mimicking electrolyte at pH 7 with variable chloride concentration, to determine the most sensitive material to sweat composition. AISI 430 is promising due to its high sensitivity to chloride concentration variations.     

L p uncertainty principles on Sturm–Liouville hypergroups

We use the Fourier analysis associated to a singular second-order differential operator Δ, and prove a continuous-time principle for the L ^p theory.     

Extremal Functions on Sturm–Liouville Hypergroups

We give an application of the theory of reproducing kernels to the Tikhonov regularization on the Sobolev spaces associated with a singular second-order differential operator. Next, we come up with some results regarding the multiplier operators for the Sturm–Liouville transform.     

Multiband small zeroth-order metamaterial antenna

A novel resonant metamaterial antenna based on the Composite Right/Left-Handed (CRLH) transmission line (TL) model is presented. The proposed small antenna is designed to operate simultaneously over multiple wireless services (UMTS-WLAN-WIMAX)