Tunnel diode oscillator-based technique has been used for quantum oscillations spectra determination of a quasi-two dimensional organic metal in pulsed high magnetic fields of up to 55 T. It is demonstrated that reliable field-dependent quantitative data can be obtained in the case of complex oscillatory spectra provided adequate data processing is conducted.

Electrical and gas sensing properties polyaniline-chloroaluminium phthalocyanine (PAni-ClAlPc) composite thin films were investigated to study the gas sensing behavior of composites. Devices (chemiresistor gas sensors) were prepared by spin coating method from PAni as the base of composites and ClAlPc (with different concentrations) as the second component onto interdigitated electrodes. The sensitivity, reversibility, response and recovery time of these thin films on exposure to different concentrations (0–2000 ppm) of CO2 gas and the suitability of different composites as materials to be used in practical gas sensors at different temperatures were investigated. The sensitivity factor of composites was obtained in a range between 0.05–7.20. PAni + 10% ClAlPc was the perfect candidate composite to fabricate gas sensor at 300 K and PAni + 15% ClAlPc at 350 K. Thus, (PAni-ClAlPc) composites have better response than pure PAni. After that, devices were exposed to humidity, an unexpected behavior was absorbed. Conductivity of thin films were increased on exposure lower RH% and decreased on higher RH%. Finally, 1000 ppm CO2 was mixed to humidity and introduced to chamber, obtained results showed the CO2 mixtures decreased the sensitivity of thin films in compare with pure CO2.

Iron (III) chloride tetraphenylporphyrin (FeTPPCl) thin films are prepared on quartz and glass substrates at room temperature by thermal evaporation technique. The X-ray diffraction showed the amorphous nature for both the as-deposited and the annealed films at 423 K in air for 2 h, whereas the powder has the tetragonal form with lattice constants of a = 13.53 $\acute\AA$ and c = 9.82 $\acute\AA$. The optical properties of FeTPPCl films are investigated using a spectrophotometric measurement of transmittance and reflectance at normal incidence of light in the wavelength range 190–2500 nm for the as-deposited and the annealed films. Absorption spectra of the films showed B, N and C absorption bands in the UV region followed by a Q-band in the visible region. The onset optical gap is determined from the analysis of the absorption coefficient values and found to be 1.53 eV for both the as-deposited and annealed films. The dispersion of the refractive index, n, is discussed in terms of Cauchy relation and the single oscillator model. The polarizability, the dispersion parameters, the ratio of free carrier concentration to the free carrier effective mass are also estimated.

We studied capacitance-voltage characteristics of ZnO thin-film transistors (TFT's), grown by metalorganic chemical vapor deposition (MOCVD). We compared two ZnO TFT's: one grown at 450 °C and the other at 350 °C. ZnO grown at 450 °C showed smooth capacitance profile with electron density of 1.5×1020 cm-3. In contrast, ZnO grown at 350 °C showed a capacitance jump when gate voltage was changed to negative voltages. Current-voltage characteristics measured in the two samples did not show much difference. We explain that the capacitance jump is related to p-type ZnO layer formed at the SiO2 interface. Current-voltage and capacitance-voltage data support that our ZnO films have anisotropic conductivity.

Nano structure films of cadmium thiogallate CdGa2S4 have been prepared by a conventional thermal evaporation technique (at substrate temperature = 303 K). These films were deposited on both glass and quartz substrates. X-ray diffraction measurements showed that CdGa2S4 compound in the powder form has a polycrystalline nature with a tetragonal structure. The as-deposited film was annealed at 673 K for 2 h under vacuum 10-3 Pa and was irradiated by 10 kGy γco rays. This resulted in a transformation to nanostructure grains of CdGa2S4 thin films. Transmission electron microscopy was carried out for all of the investigated films, which also confirmed that those films could be transformed to nanostructure grains. Optical properties of the CdGa2S4 films under investigation were examined using spectrophotometric measurements of transmittance and reflectance at normal incidence in the wavelength range 400–2500 nm. It was found that both refractive index n and absorption index k changed with the heat and irradiation treatments. The dispersion of refractive index in CdGa2S4 was analyzed according to the single oscillator model. Some dispersion parameters were determined for all investigated films. The calculated values of β (which is defined as the parameter used to determine the type of crystal) indicate that CdGa2S4 belongs to the covalent class for all films investigated. The ratio of the free carrier concentration to the effective mass N/m* was also determined. The analysis of the absorption coefficient indicated that this ternary defect chalcopyrite compound has both direct and indirect transitions in relevance to the energy gaps Eg1dir, Eg2dir and Egind, respectively. These energy values decreased by irradiation, while they increased by annealing.

We analytically formulate electromagnetic fields of circular loop-coils placed around double-structured axisymmetrical cylinders with different electrical conductivities and magnetic permeabilities. Formulae are given in terms of conductivity, permeability and frequency in a vector potential formalism subject to the appropriate boundary conditions on the cylindrical surface. The impedance of the coil is numerically computed for real and imaginary parts, whose behavior is investigated in detail on the Gauss plane for various electromagnetic properties. Our model will make it clear how the impedance of the coil depends on the conductivity and permeability in subregion of the base material, and also on the excitation frequency.

A novel embedded cylindrical-array magnetic actuator (ECAMA) is proposed and verified by experiments to provide sufficient magnetic force for spindle deviation regulation of high-speed milling process. Four I-shape silicon steel columns enclosing the spindle constitute the backbone of the ECAMA. The shape of modified concave-type yokes is designed to reduce the average air gap between magnetic poles and the spindle. In contrast to the conventional AMB (active magnetic bearing) design for which coils are usually wound on the yokes, the copper wire is wound on the I-shape silicon steel columns. As a result, the overall wound coil turns can be much increased. In other words, stronger magnetic force can be induced by ECAMA. On the other hand, to reduce the cost of ECAMA, two pairs of self-sensing modules are employed to replace the gap sensors for measurement of spindle position deviation. In order to verify the efficacy of the proposed ECAMA and the self-sensing module, high-speed milling tests are undertaken. By inspection on the precision and quality of the finish surface of workpiece, the superiority of ECAMA and the self-sensing module are assured.

Diamond-containing material (DCM) synthesized by detonation was separated into fractions. Raman and infrared spectra and X-ray diffraction patterns of the individual fractions were measured. The particles of this material were characterized by the variable ratio of the diamond (sp3) and non-diamond components. The distribution of sp3-grains in the particles was of complicated character. The fine DCM particles contained an insignificant amount of diamond. The influence of density fluctuations on the DCM formation is discussed.

This paper gives an overview on the standard crystalline silicon solar cell manufacturing processes typically applied in industry. Main focus has been put on plasma processes which can replace existing, mainly wet chemical processes within the standard process flow. Finally, additional plasma processes are presented which are suited for higher-efficient solar cells, i.e. for the “passivated emitter and rear cell” concept (PERC) or the “heterojunction with intrinsic thin layer” approach (HIT). Plasma processes for the deposition of thin dielectric or semiconducting layers for surface passivation, emitter deposition or anti-reflective coating purposes are presented. Plasma etching processes for the removal of phosphorus silicate glass or parasitic emitters, for wafer cleaning and masked and mask-free surface texturisation are discussed.

The present paper deals with the study and experimentation of a rotor current excited Vernier reluctance machine. First, the structure is introduced and the conditions on the teeth and the polarity numbers necessary for the smooth running of such a structure are presented. Then, a simple procedure is given, based on some simplifying hypotheses, to obtain the initial geometrical and electrical sizes of a designed prototype. To validate the operating principle of the structure, a prototype is designed and studied using 2D FEM. Finally, this prototype was constructed and simulation results were compared to those obtained from the prototype.

This paper focuses on the production of electricity using a thermoelectric generator placed on the human body connected to a dc-dc converter. The small difference in temperature between the hot heat source (e.g. the human body, Tb = 37 °C) and the cold heat source (e.g. ambient air, Ta = 22 °C), associated with a poor quality thermal coupling (mainly with the cold source), leads to a very low temperature gradient at the thermoelectric generator terminals and hence low productivity. Under these use conditions, the present article proposes an analysis of various ways to improve productivity given a surface capture system. Furthermore, we demonstrated, in this particular context, that maximizing the recovered electric power proves to be a different problem from that of maximizing efficiency, e.g. the figure of merit Z. We therefore define a new factor ZE, depending on the physical characteristics of thermoelectric materials, that maximizes electric power in the particular case where the thermal coupling is poor. Finally, this study highlights the benefit of sub-optimization of the power extracted from the thermoelectric generator to further improve efficiency of the overall system. We show that, given the conversion efficiency of the dc-dc converter, the maximum power point of the overall system is no more reached when the output voltage of the thermoelectric generator is equal to half of its electromotive force.

In this paper we have reported synthesis and characterization of Dy3+ and Eu3+ activated Na2Mg(PO4)F, Na2Ca(PO4)F and Na2Sr(PO4)F phosphors. These phosphors were prepared by combustion synthesis and characterized by XRD and photoluminescence techniques. Dy3+ ion gives PL emission in blue and yellow region of the visible spectrum by 385 nm excitation of the LED excitation and Eu3+ ion gives PL emission in the red region of visible spectrum under 251 nm UV-excitation (Hg excitation), respectively. Therefore, above prepared Dy3+ activated phosphors are more applicable for white LED and Eu3+ activated phosphors are more applicable for Hg excitation lamp. Hence prepared, Dy3+ and Eu3+ activated Na2X(PO4)F (X = Ca, Sr, Mg) phosphors by combustion method are very potential application in the field of lamp industry.

The two-mode Korteweg-de Vries equation (TMKdV) was proposed to describe the propagation of nonlinear waves of two different wave modes simultaneously. However, the existence of multi-soliton solutions is still unknown. In this letter we present two Hamiltonians, the conservation laws, and a Miura-like transformation of the equation. We show that the TMKdV equation has “quasi-soliton” behaviour in which waves moving in the same direction pass through each other almost without change of their wave forms except for phase shifts.

Flow visualization, basic image processing and statistical treatment are used to investigate the flow characteristics of an axisymmetric free air jet having an initially uniform velocity profile. Vortical structures and their development in the transition zone of the jet are visualized for a range of Reynolds numbers from 1300 to 1700. It is shown the onset and growth of these structures which propagate downstream of the nozzle exit at approximately 0.65 of the velocity of the mean flow. The duration of this development mechanism, before reaching the zone of turbulence, is estimated at 7.6 × 10-3. Near-field and intermediate-field region lengths, separation distance between two neighboring vortical structures, apparition frequency and jet Strouhal number are measured as functions of the Reynolds number. In particular, it is shown that the Strouhal number, which is estimated at 0.64 in our case, is independent of Reynolds numbers.