In this article, the vibrational behavior of a microcantilever (MC) with an extended piezoelectric layer in the air ambient undergoes examination. To model the vibrational motion of this type of cantilever, the Hamilton’s principle has been used. For this purpose, the MC vibrational equation has been derived by the assumption of the continuous beam based on the Euler-Bernoulli beam theory. By adopting the finite element method (FEM), the MC differential equation has been solved. In the present simulation not only van der Waals and contact forces but also the capillary forces resulting from the condensation of the water vapors in air on MC tip have been considered. The results illustrate that the force between the sample surface and the probe affects the MC amplitude; furthermore, it causes the reduction in the resonance frequency. In addition, to reduce the time delay during topography from the surface roughness, it is better to select MCs with larger width and length and smaller thickness. Furthermore, the results indicate that the best imaging takes place when the vibration is in its second vibrational mode. Finally, the effects of MC geometric parameters on the time delay between the starting moment of surface roughness and the moment of variation in the MC amplitude (surface roughness topography) have been analyzed.

The flip-flop, which has been widely used in digital circuits, has two stable states and can be used to store state information. Because traditional flip-flops based on digital circuits suffer from a barrier to higher performance, it is necessary to explore some new alternative devices. For this purpose, we utilize molecular dynamics simulations to design a molecular flip-flop, which contains one water molecule confined within a single-walled carbon nanotube. Its two states can be switched within 0.5 ps (2000 GHz), and its state information can be exported by the charged atomic-force microscope force probes. The mechanism of the flip-flop depends on the behavior of a water molecule in a nonuniform electric field. In particular, a water molecule always moves toward the location of lowest electric energy in a nonuniform electric field generated by point charges. The resulting flip-flop could be utilized for designing nanoscale devices.

This paper describes a method of calculation of the transverse distributions of electric E(x, y) and magnetic H(x, y) fields, in a rectangular waveguide within overmoded configuration – i.e., when a large number eigenmodes are present. It uses the fast Fourier transform, instead of the conventional decomposition in a series of TEMpq modes. Although not using the eigenmode decomposition, this method still exhibits the amplitude of the whole set of eigenmodes TEMpq. As an example, a single mode propagation is shown to facilitate understanding of the method. Another example is shown, using a 2D Gaussian profile as input, which contains a large number of eigenmodes (overmoded configuration). As a result, a series of 2D profiles are displayed along the longitudinal axis z of the waveguide, to show the transverse amplitude distribution of the fields E(x, y, z) and H(x, y, z) when a Gaussian profile is used at waveguide entrance. This non-standard configuration may be observed, for example, in infrared Free-Electron Lasers. This method is used here to calculate the ohmic losses which are integrated along the waveguide propagation, and which are deduced from the transverse distribution of magnetic field.

Recently, there has been a lot of interest on transparent conducting oxide (TCO) materials which have common application in solar cells and some optoelectronic devices. In this work, cadmium oxide (CdO) thin films have been deposited on glass substrates by RF reactive magnetron sputtering technique and subsequently annealed in air from 200 °C to 500 °C. The effect of annealing temperature on the structural, morphological, optical and electrical properties of CdO films is systematically investigated by X-ray diffraction, scanning electron microscopy with energy dispersive spectroscopy, atomic force microscopy, UV-visible spectrophotometer and Hall effect measurements. X-ray diffraction (XRD) studies showed that the films are polycrystalline in nature with a preferential orientation along (2 0 0) plane. Atomic force microscopy studies showed that these films are very smooth with maximum root mean square roughness of 3.13 nm. The CdO films formed at annealing temperature of 400 °C exhibited optical transmittance of 84%, electrical resistivity of 1.9 × 10−3 Ω cm and figure of merit of 1.8 × 10−3 Ω−1.

A seawater salinity sensor based on microring resonator with weak temperature dependence is proposed, which is coated by MgF2 film with positive thermo-optic coefficient. Temperature dependences of the sensor on fiber diameter, probing wavelength and coating thickness are theoretically investigated and ranges of microfiber diameters for weak temperature dependence are obtained. Under the temperature insensitive condition, sensitivity and detection limit of salinity sensing are studied. By optimizing the parameters of the sensing system, salinity sensitivity and detection limit can reach 0.03 nm/‰ and 0.13‰, respectively. The model presented here may be helpful for developing weak temperature dependence sensors for salinity sensing with high sensitivity, low detection limit and miniaturized sizes.

The EPR parameters (zero-field splitting D and g-factors g//, g⊥) of Mn5+-doped solid state laser materials Ca2(MO4)Cl (M = P, As, V) are calculated from the complete high-order perturbation formulas of EPR parameters based on the two-mechanism model for 3d2 ions in a approximately tetragonal tetrahedron. The model includes the contributions from both the crystal-field (CF) mechanism and the charge-transfer (CT) mechanism (the latter is neglected in crystal field theory). The calculated results suggest that the contribution to EPR parameters due to CT mechanism is important. So, in the cases of high valence state 3dn ions in crystals, the reasonable explanation of EPR parameters should take both CF and CT mechanisms into account.

ZnO thin films and well-aligned nanowire arrays have been synthesized via electrochemical deposition method, a low temperature and low cost synthesis method. For the ZnO nanowires growth, the electrodeposition consists of two steps: the ZnO buffer layer was firstly deposited on the substrate using galvanostatic method at room temperature following by the ZnO nanowires growth under potentiostatic method at 80 °C. This second step has also used for the ZnO thin films growth directly on substrate. The morphological and microstructural properties of the as-deposited ZnO have been characterized using scanning and transmission electron microscopy (SEM and TEM), X-ray diffraction (XRD), as well as photoluminescence spectroscopy (PL). The electrical transport of the ZnO thin films and nanowire arrays have been studied at room temperature both in the symmetrical Al/ZnO/Al electrode configuration guarantying a good Ohmic contact and in the asymmetrical Al/ZnO/Au electrode configuration demonstrating a typical Schottky contact at the interface ZnO/Au. The feature parameters such as the series resistance, the Schottky barrier height, and the ideality factor, have been systematically analyzed. Comparing the diode parameters between thin films and nanowire arrays, we deduced that about 1/3 of the ZnO nanowires come into effective contact with the top Al electrode.

In this paper, an Ag ultra thin layer was deposited on the Cu/Co film by thermal evaporation technique in the vacuum. The atomic force microscopy confirms that nanoparticles of Ag were formed on the Co magnetic layer, and subsequently, the longitudinal Kerr signal of Cu/Co/Ag was amplified more than 2 times. This enhancement is resulting from the overlap of the surface plasmon resonance in the silver with the electronic transition in the Co layer. Furthermore, we investigated the effect of transparent semiconductor SnO2 as a cap layer on the magnitude of longitudinal Kerr signal. To obtain the optimal thickness of cap layer, a numerical analysis was carried out using a 4 × 4 characteristic matrix, which takes into account multiple reflections from interfaces within the medium and light transmission through the layers.

Energy shifts in K X-ray peaks of potassium and calcium in different chemical compounds have been determined from their X-ray spectra recorded in an energy dispersive X-ray fluorescence (EDXRF) set-up. The set-up comprises low-power X-ray tube photon source and Si(PIN) detector (AMPTEK model XR-100 CR). A statistical procedure has been followed to determine the shifts and t-test was applied to find the statistical significance of the results. The shifts were determined in potassium compounds; KCl, KBr, KI, K2CO3, K2Cr2O7, K2CrO4, K2SO4, K3Fe(CN)6, K4Fe(CN)6, KHSO4, KMnO4 and KSCN with KNO3 as reference and in calcium compounds; Ca(NO3)2 · 4H2O, Ca(OH)2, CaCl2, CaCO3, CaSO3 and CaSO4 · 2H2O with CaO as reference and correlated with differences in electro-negativity, number of ligands, structural changes, type of bonding, axial distances, etc. in the compounds. The shifts in potassium compounds have been evaluated for the first time while the same for calcium compounds almost agree well with the earlier reported measurements in literature.

The effects of 1, 3 and 5 wt.% Cu additions on structure, Vickers hardness, indentation creep and corrosion behaviour of Al-5Ti-1B ternary alloy were studied and analyzed. The Al-5Ti-1B alloy exhibited a mixture of Al3Ti and TiB2 intermetallic compounds (IMCs), and Al solid solution. Additions of 1 and 3 wt.% Cu showed the same phases, indicating a complete solubility of Cu atoms in Al matrix. In addition, the Al-5Ti-1B-5Cu alloy exhibited a precipitation of CuAl2 IMC. Furthermore, additions of Cu decreased the particle size of Al matrix. This structural behaviour increased rapidly the Vickers hardness number (HV) from 643 to 1395 MPa, increased the indentation creep resistance and improved corrosion behaviour of the Al-5Ti-1B alloy. Cu is anti-corrosion phase when completely dissolved or precipitated as IMC in Al matrix.

This paper presents numerical simulations of transitions between back discharge regimes. Back discharge refers to any discharge initiated at or near a dielectric layer covering a passive electrode. In this work, a pinhole in a dielectric layer on a plane anode serves as a model for back discharge activity. We have studied transitions between back discharge regimes by varying the surface charge density on the dielectric layer and the electric field in front of the pinhole. From the variation of these two independent parameters, the back discharge regimes have been depicted as a mode diagram inspired by the experimental study of Masuda and Mizuno. The resulting diagram includes the different discharge regimes that are commonly observed in experiments. The propagation of a positive ionizing wave inside the pinhole toward its edge, and the resulting formation of a plasma zone at its exit constitute the onset stage of back discharge. From this stage, the transitions to volume discharge or surface discharge can occur. The volume discharge regime consists of the propagation of a discharge in space toward the cathode which can be superimposed with the propagation of a discharge above the dielectric layer surface. The diagram reveals the conditions for transitions between back discharge regimes.

Terbium (Tb3+) doped yttrium aluminium borate phosphors (YAl3(BO3)4) with different compositions such as YAl3(BO3)4:Tb3+, Y1−xAl3(BO3)4:Tbx3+ and YAl(3−x)(BO3)4:Tbx3+ (x = 1−8 mol.%) were synthesized using modified solid state reaction technique. The synthesized phosphor was studied using powder X-ray diffraction analysis (XRD), photoluminescence spectroscopy (PL), high resolution-scanning electron microscope (HR-SEM). Lattice parameters are calculated for the Tb3+ doped and substituted YAB phosphors using XRD analysis. The phosphor exhibits green emission at 572 nm with 375 nm of excitation. It is found that the Tb3+ ions substitution in the sites Y3+ and Al3+ ions in Y1–xAl3(BO3)4:Tbx3+ and YAl(3–x)(BO3)4:Tbx3+ leads to overlapping of energy levels which affects the PL intensity of the phosphor significantly. Thus, phosphor synthesized with the composition YAl3(BO3)4:Tb3+, acquires higher photoluminescence (PL) intensity when compared to Y1–xAl3(BO3)4:Tbx3+ and YAl(3–x)(BO3)4:Tbx3+ phosphors. Temperature dependent PL property (thermal quenching studies) of YAl3(BO3)4:Tb3+ was also performed up to 250 °C. Further, it is found that the PL intensity of the studied phosphor is comparable with commercial green phosphor. HR-SEM analysis demonstrates that the phosphors are grown as nanorods with an average diameter of 50–80 nm and length 250–500 nm.

This work reports synthesis of PbS quantum dots (QDs) embedded in the poly-vinyl alcohol (PVA) in the presence of graphene quantum dots (GQDs) by the low cost and simple method of chemical bath deposition. The as-synthesized products were characterized by X-ray diffraction, transmission electron microscope and optical studies; absorption and photoluminescence measurements. Results showed that in comparison with GQDs and PbS/PVA, photoluminescence intensity of PbS/PVA/GQDs was improved and this could be attributed to rigidity of the local environment, PVA passivation and energy transformation between GQDs and PbS QDs. These analyses determined good distribution of PbS QDs on GQDs planes which is promising for practical applications in nanotechnology.

We present a plasmonic splitter based on metal-insulator-metal (MIM) structure. This splitter consists of two parallel waveguides and two resonators. One resonator is a ring tangentially connected with the two waveguides, and the other resonator is a semi-ring directly connected to the lower waveguide. The finite-difference time-domain (FDTD) method is used to numerically analyze the transmittance spectra of the splitter. The results show that this splitter is a beam splitter when the wavelength of the incident wave is around 1355 nm or 1553 nm. This splitter can also be regarded as a power splitter. To our knowledge, this is the first designed surface plasmon polaritons (SPPs) splitter which utilize both the communication wavelengths at around 1310 nm and 1550 nm. This characteristics show potential applications in future optical circuits.

The electrical explosion characteristics of Schottky diode for one-shot switch applications were acquired by analysis of photographs of high speed camera and current-voltage histories. Four types of connections among Schottky diode, top electrode and discharge capacitor were studied. Results show that type B has the longest time (1.4 ms) of optical radiation and highest energy consumption, which makes it easier to turn on the switch. The charge flux of plasma was determined to be 24.5 Q/(s m2) by parallel electrode plates method. Atomic emission spectroscopic measurements were devoted to determine plasma temperature and density during electrical explosion. Results show that temperature is between 4000 K and 5000 K, and density is about 1024 m−3. The one-shot switch based on ceramics has been fabricated and characterized and the results show that the peak current and the rise time are about 963.77 A and 381.6 ns, respectively.

First-principles calculations based on density functional theory (DFT) have been carried out to investigate the effects of crystal defects (intrinsic vacancy defects and ion doping) on the microwave dielectric response and the correlative electromagnetic properties of α-MnO2 systematically. The possible role of crystal defects in electromagnetic performance is studied utilizing density of states (DOS) and the bond length between the manganese and oxygen. Lattice distortion is induced by the introduction of crystal defects. The spin-electronic DOS demonstrates that Ni doping enhances the spin-polarization of MnO2, which indicates that the Ni-doped MnO2 possesses certain magnetic characteristic, which is helpful for magnetic loss. The emergence of a new defect mode, contributes to the relaxation polarization phenomenon, so as to enhance the dielectric loss ability. In addition, through the change of the bond length and pseudo gap width, it can be learned that the bond strength and covalency of Mn-O bonds are weakened, which increases the dielectric loss of MnO2. The results throw light on the exploration of theoretical research on the microwave absorbing properties of MnO2 with crystal defects.

We report experimental results on the degree of radiation damage in two duo-lateral position sensitive detectors (LPSDs) exposed to 193 nm and 253 nm ultraviolet (UV) beam. One of the detectors was an in-house fabricated n+p LPSD and the other was a commercially available p+n LPSD. We report that at both wavelengths, the degradation damage from the UV photons absorption caused a much more significant deterioration in responsivity in the p+n LPSD than in the n+p LPSD. By employing a simple method, we were able to visualize the radiation damage on the active area of the LPSDs using 3-dimensional graphs. We were also able to characterize the impact of radiation damage on the linearity and position error of the detectors.

Partial discharge (PD) in power transformers is one of the prime reasons resulting in insulation degradation and power faults. Hence, it is of great importance to study the techniques of the detection and localization of PD in theory and practice. The detection and localization of PD employing acoustic emission (AE) techniques, as a kind of non-destructive testing, plus due to the advantages of powerful capability of locating and high precision, have been paid more and more attention. The localization algorithm is the key factor to decide the localization accuracy in AE localization of PD. Many kinds of localization algorithms exist for the PD source localization adopting AE techniques including intelligent and non-intelligent algorithms. However, the existed algorithms possess some defects such as the premature convergence phenomenon, poor local optimization ability and unsuitability for the field applications. To overcome the poor local optimization ability and easily caused premature convergence phenomenon of the fundamental genetic algorithm (GA), a new kind of improved GA is proposed, namely the sequence quadratic programming-genetic algorithm (SQP-GA). For the hybrid optimization algorithm, SQP-GA, the sequence quadratic programming (SQP) algorithm which is used as a basic operator is integrated into the fundamental GA, so the local searching ability of the fundamental GA is improved effectively and the premature convergence phenomenon is overcome. Experimental results of the numerical simulations of benchmark functions show that the hybrid optimization algorithm, SQP-GA, is better than the fundamental GA in the convergence speed and optimization precision, and the proposed algorithm in this paper has outstanding optimization effect. At the same time, the presented SQP-GA in the paper is applied to solve the ultrasonic localization problem of PD in transformers, then the ultrasonic localization method of PD in transformers based on the SQP-GA is proposed. And localization results based on the SQP-GA are compared with some algorithms such as the GA, some other intelligent and non-intelligent algorithms. The results of calculating examples both stimulated and spot experiments demonstrate that the localization method based on the SQP-GA can effectively prevent the results from getting trapped into the local optimum values, and the localization method is of great feasibility and very suitable for the field applications, and the precision of localization is enhanced, and the effectiveness of localization is ideal and satisfactory.

Interaction of oxygen with the Mo(1 1 2) surface precovered by submonolayer beryllium films with various coverage degrees (θBe < 1) has been investigated by Auger electron spectroscopy, LEED and contact potential difference techniques. We have studied the effect of Be coverage degree on the oxygen adsorption kinetics, atomic structure and electronic properties of the O/Be/Mo(1 1 2) system. Contrary to the case of full-monolayer Be precoverage (θBe = 1), beryllium submonolayers can speed up the initial adsorption kinetics of oxygen by a factor of 10. The high sticking coefficient of oxygen on the Be/Mo(1 1 2) surface at θBe < 1 can be explained by the existence of areas on Mo(1 1 2) that are free of Be and provide fast oxygen adsorption, with O adatoms migrating further to the areas covered with Be (the spillover effect). The creation of beryllium oxide even on limited surface areas substantially decreases the oxygen sticking coefficient. This effect may originate from the surface deformation due to a structural misfit between the Be/O layer and the substrate. The coadsorbed Be/O layers with θBe < 1 modify the work function to values between those specific of the O/Be/Mo(1 1 2) systems with θBe = 0 and 1, which complies with the heterogeneous adlayer model.