High density rewritable media for near-field recording are fabricated and their writing and readout characteristics are examined. High density substrates for rewritable media are prepared using a phase transition mastering technique to overcome the limitation of the deep UV laser recorder. A cover-layer with a UV curable material is coated on the rewritable media and its surface properties are discussed to apply for cover-layer incident near-field recording configuration. The effective numerical aperture of a pick up with a solid immersion lens is 1.46, which could cope with the recording density of about 70 GB per disc. The performance of readout signals were investigated, and compared the properties between 320 nm and 200 nm of the track pitch in the substrate.

We show here that at a certain externally applied static magnetic field of moderate value, photonic band gap (PBG) is induced at optical frequencies in a stable colloidal dispersion containing a mixture of micron and nano sized magnetite spheres. The PBG is found to depend on the size of microspheres and is observed for only TM mode of the incident waves. Effect of nonmagnetic doping on the PBG is also discussed. The observed effects are attributed to the magnetically induced morphological dependent resonance (MDR) in the micron sized magnetic spheres. The technique to induce PBG may be easily amenable for lab-on-chip devices.

ZnS and Ni doped ZnS nanoparticles were synthesized through chemical precipitation method using a high-boiling solvent. The nanocrystillanity of the prepared nanostructures is confirmed by X-ray diffraction (XRD). The mean crystal size obtained by full width half maxima (FWHM) analysis is 3.2 nm for ZnS and 4.3 nm for ZnS:Ni. An optical absorption study conducted in UV-vis range 150–800 nm reveals the transparency of these nanocrystals in entire visible range but not in ultraviolet range. The results based on optical analysis yield band gap values as 3.92 eV for ZnS and 3.88 eV for ZnS:Ni nanoparticles. The electrical resistivity data reveals semiconducting behaviour to both compositions. Fitting of resistivity data in Mott's variable range hopping model (VRH) shows that nickel (1.5%) doping in ZnS reduces gap parameters from 4.78 to 4.22 eV. Based on this model the carrier density, energy gap and hopping distances are calculated for both pure and Ni modified nanocrystals.

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 (sp 3) and non-diamond components. The distribution of sp 3-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.

As the product of the wear process, the wear particles record the rich information to reflect the state of the equipment's inner abrasion. Analysis of the wear particles in lubricating or hydraulic oils becomes one important branch of diagnosing the wear states of machine parts. Extracting characteristic parameter is an indispensable means to analyse wear particles. In this paper, a method to extract the characteristic parameters of the wear particle boundary based on chaos theory has been discussed. The concept of boundary wave has been firstly conducted, and then based on the Shannon entropy and the theory of phase reconstruction, the concept and the arithmetic of the singular entropy have been conducted. It has been shown that the boundary wave of the wear particles is characterised as chaos, so the singular entropy can be used to describe the complexity of the boundary of the wear particles. Therefore the singular entropy can be considered as one of the characteristic parameters of the wear particles.

A multi-channeled filter that bases on the effect of photon tunneling through the coupled-cavity resonators is designed. Applying the tight-binding model and the transfer matrix method we analyze its transmission mechanism and study its transmission properties. Through the coupling of cavities, the single resonant mode is split into some discrete resonant peaks forming many transmission channels. Through adjusting the thickness of air layer we make the intervals of channelsapproximately equivalent. The whole position of channels can be moved through changing the incident angle.

Laser Thomson scattering technique has been used to measure the electron density and the electron temperature in a pulsed single filament micro-discharge. The single filament discharge was created between a needle and a hemispherical electrode surface. The spatial and temporal profiles of the electron density and the electron temperature in the center of the discharge gap have been measured. The absolute values of the electron density and electron temperature were found to decrease with time and away from the discharge axis. These profiles have been measured for the first time.

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.

Photoacoustic imaging takes the merits of simultaneous high optical contrast and low acoustical scattering, and has been proven to be a potential tool for noninvasive diagnosis of cancer tumors in an early stage. An integrated prototype multi-element synthetic aperture focusing photoacoustic imaging system using real-time digital beamformer (96 scan lines of each frame image) is designed, fabricated and tested. The combined system with multi-channel signal acquisition and real-time digital beam-formation module implements real-time dynamic receiving focus and apodization technique to process the photoacoustic signal, which is captured by a 128-element linear ultrasonic transducer array. The data acquisition and synthesis time can be accelerated in less than 4 s of each view without data average. The in vivo experiments were performed with a clear view of the blood vessels network of mouse tumor. The results demonstrate that the multi-element synthetic aperture focusing photoacoustic imaging system with real-time digital beamformer technique has the potential in the practical fast photoacoustic imaging for clinical diagnosis.

We compared the hydrogen uptake weight percentages (wt.%) of different carbonized materials, before and after modification, for their application in hydrogen storage at room temperature. The Sievert's method [T.P. Blach, E. Mac, A. Gray, J. Alloys Compd. 446-447, 692 (2007)] was used to measure hydrogen uptake values on: (1) Taiwan bamboo charcoal (TBC), (2) white charcoal (WC), (3) single-walled carbon nanotubes (SWCNTs) bought from CBT Inc. and (4) homemade multi-walled carbon nanotubes (MWCNTs) grown on TBC. Modified samples were coated with a metal catalyst by dipping in KOH solutions of different concentrations and then activated in a high temperature oven (800 °C) under the atmospheric pressure of inert gas. The results showed that unmodified SWCNTs had superior uptake but that Taiwan bamboo charcoal, after modification, showed enhanced uptake comparable to the SWCNTs. Due to TBC's low cost and high mass production rate, they will be the key candidate for future hydrogen storage applications.

The bombardment of ions and electrons at the substrate has been studied by varying the magnetic field distribution and the grid-target distance in a triode magnetron sputtering system. The substrate temperature was correlated with the substrate current density and with the type of species bombarding the substrate. The results indicate a possibility to modify and control the bombardment at the substrate surface from predominantly electronic to predominantly ionic, which increases the substrate temperature from 383 K to 473 K, respectively.

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, T b = 37 °C) and the cold heat source (e.g. ambient air, T a = 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 Z E , 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 recent experimental observations of triple tracks in solid-state nuclear track detectors, CR-39, during Pd/D co-deposition experiments indicate that the triple tracks are due to ~14 MeV neutrons, which appear to originate from “hot” fusion reaction D(t,n)4He. Nuclear theory interpretation of the origin of ~14 MeV neutrons is presented in terms of a sub-threshold resonance reaction involving (T + p) resonance state of 4He* (J π = 0+) at 20.21 MeV, which produces 1.01 MeV T. An upper limit of the branching ratio, R(n)/R(T), between neutron production rate and tritium production rate is calculated to be R(n)/R(T) < 10-4. Experimental tests of the proposed theoretical interpretation are proposed.

Thermo-inductive testing is a new technique used for health inspection on different components of automotive and aeronautic industries. Defect detection is based on the modification of induced eddy current and temperatures due to the presence of defects. The temperature change propagated at the surface of the specimen can then be detected by an infrared camera. In this work, a 3D numerical model of this technique is developed and applied to aeronautic materials. Results obtained are compared with the infrared thermography method to demonstrate the relevance of the new technique.

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

Consuming chemical energy, fuel cells produce simultaneously heat, water and useful electrical power [J.M. Andújar, F. Segura, Renew. Sust. Energy Rev. 13, 2309 (2009)], [J. Larminie, A. Dicks, Fuel Cell Systems Explained, 2nd edn. (John Wiley & Sons, 2003)]. As a matter of fact, the voltage generated by a fuel cell strongly depends on both the load power demand and the operating conditions. Besides, as a result of many design aspects, fuel cells are low voltage and high current electric generators. On the contrary, electric loads are commonly designed for small voltage swing and a high V/I ratio in order to minimize Joule losses. Therefore, electric loads supplied by fuel cells are typically fed by means of an intermediate power voltage regulator. The specifications of such a power converter are to be able to step up the input voltage with a high ratio (a ratio of 10 is a classic situation) and also to work with an excellent efficiency (in order to minimize its size, its weight and its losses) [A. Shahin, B. Huang, J.P. Martin, S. Pierfederici, B. Davat, Energy Conv. Manag. 51, 56 (2010)].This paper deals with the design of this essential ancillary device. It intends to bring out the best structure for fulfilling this function. Several dc-dc converters with large voltage step-up ratios are introduced. A topology based on a coupled inductor or tapped inductor is closely studied. A detailed modelling is performed with the purpose of providing designing rules. This model is validated with both simulation and implementation. The experimental prototype is based on the following specifications: the fuel cell output voltage ranges from a 50 V open-voltage to a 25 V rated voltage while the load requires a constant 250 V voltage. The studied coupled inductor converter is compared with a classic boost converter commonly used in this voltage elevating application. Even though the voltage regulator faces severe FC specifications, the measured efficiency reaches 96% at the rated power whereas conventional boost efficiency barely achieves 91.5% in the same operating conditions.

We present in this paper a 3D electromagnetic formulation to describe two conductors in electric contact with each other, submitted to the field of a coil in which an AC current is flowing. One of the two conductors is described by the t-ϕ formulation, the other conductor is described by the surface impedance boundary condition. The proposed coupled formulation has been validated with a numerical example with a simple geometry. This coupled formulation has then been applied to a numerical example on which a crack has to be detected. It is composed of a non magnetic tube embedded in a thick steel tube sheet, submitted to the field of a coil.

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.