The capacitance between two adjacent nodes on an infinite square grid of identical capacitors can easily be found by superposition, and the solution is found by exploiting the symmetry of the grid. The mathematical problem presented in this work involves the solution of an infinite set of linear, inhomogeneous difference equations which are solved by the method of separation of variables.

A single and simple graph is proposed, to visualize the impact of all the numerous parameters playing a role in the metal-oxide-semiconductor (MOS) transistor characteristics: doping and permittivity of the semiconductor, thickness, permittivity and charge of the oxide, temperature, and finally gate, drain and substrate voltages. In addition, MOS structure and capacitance properties are presented.

We consider possible magnetic symmetries of two-dimensional square lattices with circular ferrite rods magnetized by a uniform dc magnetic field. These structures can be used as tunable and nonreciprocal photonic crystals. Classification of eigenmodes in such crystals and compatibility relations are discussed on the basis of magnetic group theory and the theory of (co)representations. Some general electromagnetic properties of the magnetic crystals such as change in the basic domain of the Brillouin zone, change of symmetry in limiting cases, bidirectionality and nonreciprocity, symmetry relations for the waves and lifting of eigenwave degeneracies by dc magnetic field are also discussed.

Magnetic compensation of gravity forces, similar to the space conditions of “microgravity”, needs the production of a uniform magnetic force field. We derive here a basic mathematical result that shows the impossibility to establish exact gravity compensation in a finite volume. The imperfection of compensation can be, however, quantified and a relation is derived between homogeneity accuracy and compensation volume in a cylindrical symmetry. We study how the use of inserts made of saturated ferromagnetic materials can modify the homogeneity of magnetic force field. In order to illustrate this result, an iron insert has been numerically calculated for the particular case of gravity compensation of H2 in a 10 T superconducting coil. An experimental test has been carried out on a H2 vapour bubble very close to its gas-liquid critical point. Near the critical point the gas-liquid interfacial tension is vanishing, then any bubble deformation from the ideal spherical shape reveals the non-homogeneities in the magnetic compensation force.

X-ray diffraction, Mössbauer spectroscopy, Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) techniques were used to characterize the Fe-C phases in the soots synthesized by the DC arc discharge method. Various equilibrium and non-equilibrium Fe-C compounds were identified, with fractions depending on both the location in the reactor and the helium gas pressure. The soots obtained are composed of the same five phases (C-graphite, α-Fe, γ-Fe, Fe3C and Fe5C2) whatever the helium gas pressure and wherever they are situated in the reactor. However, the location in the reactor has a considerable influence on the size of the particles in the nanostructure. The Fe-C compounds in the Pyrex vessel samples (CL) seem only to be present in the form of nanoparticles embedded in an amorphous gangue, while the water-cooled copper cylinder samples (RS) contain, in addition to these nanoparticles, large composite crystalline particles.

N-type silicon presents several advantages compared to p-type material, among them, the most important is the small capture cross sections of metallic impurities, which are neatly smaller. As a consequence lifetime and also diffusion length of minority carriers should be neatly higher in n-type than in p-type, for a given impurity concentration. This is of a paramount interest for multicrystalline silicon wafers, in which the impurity-extended crystallographic defects interaction governs the recombination strength of minority carriers. It is experimentally verified that in 1.2 $\rm \Omega $ cm raw wafers lifetimes about 200 $\mu $s and diffusion lengths around 220 $\mu $m are measured. These values increase strongly after gettering treatments like phosphorus diffusion or Al-Si alloying. Scan maps reveal that extended defects are poorly active, although in regions where the density of dislocations is higher than 106 cm-2. Abrupt $p^{+}n$ junctions are obtained by Al-Si alloying after annealing between 850 and 900 °C, which could be used for rear junction cells. Such cells can be processed by means of similar processing steps used to make conventional p-type base cells.

The non-uniformity of responsivity of photodiodes and thermal detectors limits the accuracy of their calibration. Spatial non-uniformity properties of a pyroelectric radiometer, a thermopile detector, silicon, germanium and indium gallium arsenide photodiodes are investigated in the scope of our work. Silicon type photodiodes showed best uniformity characteristics among the analysed photodiodes and detectors. Significant changes have been found in the spatial responsivity close to the band gap of silicon. The spatial responsivity of thermopile detector was measured at two different wavelengths and no wavelength dependence was observed.

This paper presents a study of the ultrasonic wave propagation in a cylindrical layer-substrate structure of an infinite length. We determine the dispersion curves of the structure, the displacements field in the structure and the impact of the contact quality between the layer and the substrate. The industrial application aimed by our study is the control of the massive machine elements with cylindrical cavities coated and exposed to corrosion. The obtained results show that some modes of propagation are insensitive to the layer thickness. Therefore, these modes can be generated during the ultrasonic control of the layer. In addition, for the dimensions considered here, the second mode of propagation is the most adapted for the detection of defects in the vicinity of the internal layer wall. In addition, our study shows the possibility of characterization of the quality of contact between the layer and the substrate from the analysis of dispersion curves of the structure.

This paper presents a study of guided ultrasonic waves in a tri-layer structure composed of two aluminum sheets bonded by an adhesive layer of resin epoxy. Numerical resolution, of high accuracy, of the characteristic equation permitted to determine the dispersion curves and the displacements field in the structure. A new interpretation of the dispersion curves of the tri-layer structure is proposed highlighting the existence, for each propagation mode, of a portion where this mode follows the mode of an adhesive layer and another portion where it follows the mode of an aluminum sheet. From dispersion curves, we determine the displacements field of the tri-layer structure showing that the displacement takes place in the adhesive layer when the mode of propagation is in the first portion and it is dominating in the aluminum sheets if the mode is in the second portion. In addition, we show the possibility of characterization of the quality of bond of the two aluminum sheets from the analysis of dispersion curves of the structure.

The aim of this work is to present a new indirect and noninvasive method for the measurement of the Newtonian blood viscosity. Based on an integral form of the axial Navier-Stokes equation, this method is particularly suited for in vivo investigations using ultrasonic arterial blood velocity profiles. Its main advantage is that it is applicable to periodic as well as non periodic flows. Moreover it does not require classical filtering methods enhancing signal to noise ratio of the physiological signals. This method only requires the knowledge of the velocimetric data measured inside a spatially and temporally optimized zone of the Doppler velocity profiles. The results obtained using numerical simulation as well as in vitro or in vivo experiments prove the effectiveness of the method. It is then well adapted to the clinical environment as a systematic quasi on-line method for the measurement of the blood viscosity.