Cd1-X ZnX Te is one of the II-VI ternary semiconductor materials whose band gap can be tailored to any value between 1.48 eV to 2.26 eV as X varies from 0 to 1. It is promising material for high efficiency solar cells, switching and other optoelectronic devices. Cd0.4Zn0.6Te thin films have been deposited on ultra-clean glass substrates by screen printing method followed by sintering process. X-ray diffraction studies revealed that the films are polycrystalline in nature, single phase exhibiting wurtzite (hexagonal) structure with strong preferential orientation of grains along the (101) direction. The optical band gap of the films has been studied using absorption spectra by using double beam spectrophotometer. The dc conductivity of the films was measured in vacuum by two probe technique. The results of present investigation will be useful in characterizing the material Cd1-X ZnX Te for its applications in photovoltaics. Sintering is a very simple and viable method compared to other cost intensive methods.

Zn1-x Mnx O (x = 0.01, 0.02, 0.05, 0.1, and 0.15) powders were prepared by solid-state reaction processes. The structural and magnetic properties of the powders were investigated. X-ray diffraction (XRD) analysis of the samples indicates the presence of wurtzite crystal structure similar to pure ZnO and absence of any other secondary phase till 5% Mn doping. This suggests that doped Mn2+ ions substitute Zn2+ sites. However, Raman results revealed the presence of secondary phase even at very low Mn doping (2%), which demonstrates that Mn does not incorporate completely the ZnO lattice. The powders exhibit ferromagnetism at low temperatures and paramagnetic at room temperature. Transition from ferromagnetic to paramagnetic is highlighted by measurements at 230 K.

Copper nitride films were prepared on glass and silicon substrates by reactive direct current magnetron sputtering at various N2-gas partial pressures at room temperature. The N2 partial pressure influenced the structural, electrical and optical properties of the deposited films. The X-ray diffraction measurement showed the phase change of the preferred orientation of Cu3N planes of samples from Cu-rich (111) planes to N-rich (100) planes. The surface resistivity of glass substrate Cu3N films was between 1675 and 58 200 Ω/cm2 and for silicon substrate films surface resistivity was between 13.2 and 2380 Ω/cm2. As is observed surface resistivity strongly affected by structures of the films. Deposition rate was influenced by the amount of argon gas since they are heavier than nitrogen atoms changes from 43 nm/min to 26 nm/min. Calculated band gap energy of the samples show a sharp enhancement from 1.4 eV to 1.95 eV by increasing nitrogen content in working gas.

The main force that detaches a molten droplet from the electrode (wire) during arc welding is the interaction of the arc current with its own magnetic field. The magnitude of this force depends on the current distribution inside the droplet. A method to regulate the current distribution is proposed. The current redistribution is achieved by striking an additional arc with the droplet serving as a cathode of this arc. By the current redistribution it is possible (i) to decrease the threshold current of the globular to spray transition during GMA welding, (ii) to achieve this transition in different plasma gases, and (iii) to control the propelling direction of the detaching droplet. Some preliminary experiments confirm the proposed method.

The thermal behaviour of a rotating roller, subjected to surface heat sources is studied in this paper using an analytical solution, developed for this purpose. The roller is composed of a solid cylinder, rotating with a constant angular velocity, and is heated at its peripheral surface by two different heat sources. The analytical solution is entirely explicit and does not necessitate any hypothesis neither on the speed nor on the physical or geometrical parameters of the roller. The characteristic parameters are presented in dimensionless forms and are used to analyse the temperature distribution as function of their variations. Thermal maps are also presented using the proposed solution. They show that the thermal gradients are localized at the vicinity of the friction zone, and that the thermal gradients zones decrease when the angular speed increases.

The initial state development of breakdown is explained on the basis of bubble theory. Application of dc voltage to electrodes immersed in oil results in the creation of small channels. In the next phase an arc channel between the electrodes is formed. Resistance of the plasma channel changes from a few ohms to a few hundreds mΩ due to Joule heating caused by high arc currents which flows through this channel. The dynamics of the arc current depends on the parameters of the outer circuit and is represented by the RLC circuit.

Perovskites BaTi1 - z Mz O3 + δ (M = Fe, Cr, Mn, Co) has been sol-gel synthesized. Their transformation point of ferroelectric to paraelectric and the latent heat of the transformation were found a little lower than those for pure BaTiO3 (BTO), respectively. Layered composites Tb1 - x Dyx Fe2 - y –BaTi1 - z Mz O3 + δ have been fabricated. Their magnetoelectric (ME) effect has been investigated. All the bilayers containing the doped BTO displayed a stronger ME effects than that containing pure BTO does. The bilayer Tb1 - x Dyx Fe2 - y –BaTi0.99Cr0.01O3+δ was observed to show a larger ME coupling in the composites containing other doped BTO. While Tb1 - x Dyx Fe2 - y –BaTi0.985Fe0.015O3 + δ showed the largest ME effects in the bilayers Tb1 - x Dyx Fe2 - y –BaTi1 - z Fez O3 + δ (0 ≤z ≤ 0.02). Additionally, the ME voltage coefficient for the trilayers Tb1 - x Dyx Fe2 - y –BaTi0.99M0.01O3 + δ –Tb1 - x Dyx Fe2 - y was observed to be two or three times larger than that observed in the bilayers composed by the same substances. Theoretical analyses have been given for these observations. All the results suggest that the doped BTO can be a new choice of piezoelectrics in fabricating layered ME composites.

The high order perturbation formulas of the electron paramagnetic resonance (EPR) parameters (the g factors and the hyperfine structure constants) are established for a 3d 9 ion in orthorhombically compressed octahedra. These formulas are applied to the investigations of the EPR spectra and local structures for the substitutional Cu2+ centers in the wolframite-type tungstates AWO4 (where A = Cd, Zn, Mg). Based on the studies, the [CuO6]10- clusters are found to experience the local planar bond length variations δR' (≈0.096, 0.021 and 0.028 Å for CdWO4, ZnWO4 and MgWO4, respectively) along X and Y-axes. These values are quite different from the host planar bond length variations δR (≈0.013, 0.069 and 0.005 Å) for the A2+ sites in the pure tungstates. The above local bond length variations in the impurity centers can be attributed to the Jahn-Teller effect and size mismatching substitution. The theoretical EPR parameters based on the above local structures agree well with the experimental data. By adopting the uniform theoretical formulas and fewer adjustable parameters in this work, the improvements are achieved for the EPR parameters as compared with the previous calculation results.

Laser-induced breakdown spectroscopy (LIBS) has been used for brass plasma diagnostic using a Nd:YAG laser at 1064 nm. Optimal experimental conditions were evaluated, including repetition rate, number of laser shots on sample, and laser energy. The plasma temperatures and the electron number densities were determined from the emission spectra of LIBS. Cu and Zn spectral lines were used for excitation temperature calculation using Saha-Boltzmann distribution as well as line pair ratio. It was found that, the excitation temperature calculated by using Saha-Boltzmann distribution and line pair ratio methods are not the same. The electron number density has been evaluated from the Stark broadening of Hα transition at 656.27 nm and the calculated electron number density is agreement with literature.

In this study TiO2 nanotubular fibers were prepared and subsequently loaded with CdS nanoparticles to obtain visible light activate nanofibers with modified structure. Preparation of TiO2 fibers was based on templating method and Liquid phase deposition technique (LPD) with cellulose fibers as templates. Using LPD, thickness of the TiO2 layer could be controlled precisely by adjusting the reaction conditions, therefore after removal of the template, the resulting material has a fibrous structure, mimicking the cellulose fibers shape. CdS nanoparticles were synthesized by thermochemical growth method and attached to TiO2 fibers through impregnation method. The pure composite nanofibers were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and UV-visible spectroscopic techniques. To investigate the photoactivity of CdS/TiO2 fibers, using MB decomposition test under visible light irradiation was studied and compared with that of pure TiO2 nanofibers and CdS nanoparticles. A possible mechanism of sensitization of TiO2 with CdS nanoparticles and visible light MB decomposition was also discussed. Photocatalytic decomposition test under visible light irradiation shows that these novel structures are appropriate for visible photocatalysis applications.

Classical electromagnetism provides limited means to model electric generators. To extend the classical theory in this respect, additional information on microscopic processes is required. In semiconductor devices and electrochemical generators such information may be obtained by modelling chemical composition. Here we use this approach for the modelling of dye-sensitised solar cells. We simulate the steady-state current-voltage characteristics of such a cell, as well as its transient response. Dynamic simulations show optoelectronic hysteresis in these cells under transient light pulse illumination.

In this work, TOPO(tri-octyl phosphine oxide)/TOP(tri-octyl phosphine)-capped cadmium selenide (CdSe) quantum dots (QD's) of varied sizes (5–9 nm) prepared at different input Cd:Se precursor ratio's (1:1–2:1) using chemical route were dispersed in conducting polymer matrices viz poly[2-methoxy,5-(2-ethyl-hexyloxy)-1,4-phenylene vinylene] (MEH-PPV) and poly(3-hexylthiophene) (P3HT) respectively. The properties of polymer:CdSe nanocomposites are evaluated by means of photoluminescence (PL), UV-VIS absorption, Raman, Fourier transform infrared (FTIR), transmission electron microscopy (TEM) and atomic force microscopy (AFM) techniques respectively. The emission and structural properties of polymer-CdSe nanocomposites are found to be dependent on their morphology. The better quality of smallest sized CdSe QD's (size ~5 nm) in conjunction with regioregular P3HT polymer, leads to higher photostability of P3HT:CdSe QD's nanocomposites as compared to that for corresponding MEH-PPV:CdSe nanocomposites, thus making it as an attractive candidate for hybrid solar cells application.

In a calculation of demonstrative type collective, laser-like behavior of low energy nuclear fusion reaction of deuterons in crystalline environment is investigated. It is found that the reported extra 4He production can be appropriately described with a model well known in quantum electronics in which the quantized boson (4He) field interacts with an ensemble of two-level systems in a crystal resonator. The estimated life times of the two levels indicate that population inversion may be achieved. Thresholds of the deuteron number of the sample and of the electric current density of the pumping electrolysis are estimated in the calculation by analyzing the gain parameter and some other characteristics of the process. An explanation for the experimentally observed threshold behavior of the electric current density is given. A loss of a special type, that is the degenerate parametric amplifier mechanism, is suggested to be responsible for the difference between the expected and observed energies of the outgoing charged particles.

Simultaneous measurement technique of evaluating the doped optical fibers (DOF) parameters is a suitable scheme for DOF production industries. In this paper, we introduce a novel technique to characterize simultaneously the main parameters of DOF such as absorption and emission cross-sections (ACS, ECS), background loss coefficient (BLC), and low dopant concentration using the gain equation of DOFs. We used this new method to determine the ACS, ECS, BLC in a standard sample of Al-P-Erbium doped optical fiber. The results have been analyzed and compared with other reports.

This paper, which deals with the winding modeling of ac multi-phase machines with a regular distribution of the stator slots, details an original matrix modeling of the stator winding. First, the properties of the balanced multi-phase windings (with integral-slot and fractional-slot patterns) are analysed. The winding function approach, one of the most common way to model the winding distribution effects on the stator rotating field, is then introduced. For multi-phase machines, it will be shown that the pole number generated by the winding distribution depends on a new parameter: the circularity index. The discrete nature of the winding, imposed by the stator slots, leads to the development of a discrete modeling of the winding obtained from sampling the winding function: two matrices, the winding function matrix and the distribution function matrix, are introduced to characterize the multi-phase winding. This matrix approach is thus a concise way to calculate the winding factors and to estimate the set of self and mutual stator inductances for smooth air gap multi-phase machines. A particularly original method of obtaining an analytical expression for the leakage mutual inductance is described. The results are validated with two experimental 5-phase PM machines by using experimental measurements and numerical simulations.

The metamaterial absorber composed of random dendritic cells has been investigated at microwave frequencies. It is found that the absorptivities come to be weaker and the resonant frequency get red shift as the disordered states increasing, however, the random metamaterial absorber still presents high absorptivity more than 95%. The disordered structures can help understanding of the metamaterial absorber and may be employed for practical design of infrared metamaterial absorber, which may play important roles in collection of radiative heat energy and directional transfer enhancement.

In this paper, the transportation principles of a sine-modulated spherical light coming from a point light source in an optically homogeneous scattering media are present for the first time to our knowledge. Both a focused ultrasound pulse and a broadened light beam are employed to produce the point light source emitting the sine-modulated light. Firstly, based on the transportation principles, the penetration depth of the media is deduced by moving the ultrasound beam and detecting the changes of the ultrasound-modulated light signal outside the media. Then, the diffuse reflection ratio of the media is deduced by measuring the reflected light outside the media. At last, with the combinations among the penetration depth, the diffuse reflection ratio and other optical properties, the optical properties of the media are determined by mathematic calculating.

We investigated the electrical properties of polyaniline-coated magnetic nanoparticles as a signal transducer for application in a disposable membrane strip biosensor. The size of these particles (~100 nm) was investigated by a transmission electron microscope. Electrical properties of these nanoparticles were investigated by four-point probe measurements and I-V measurements. Polyaniline-coated magnetic nanoparticles had a resistivity of 0.385 Ω cm and showed ohmic behavior. Resistance decreased with increasing concentration of polyaniline. We also demonstrated that the resistance decreased with increasing concentration of biotinylated IgG conjugated with these nanoparticles.

This paper presents a novel pulse-width modulation technique based sliding mode approach for direct torque control of an induction machine drive. Methodology begins with a sliding mode control of machine's torque and stator flux to generate the reference voltage vector and to reduce parameters sensitivity. Then, the switching control of the three-phase inverter is developed using sliding mode concept to make the system tracking reference voltage inputs. The main features of the proposed methodologies are the high tracking accuracy and the much easier implementation compared to the space vector modulation. Simulations are carried out to confirm the effectiveness of proposed control algorithms.