Electrical analysis of inter-growth structured Bi_4Ti_3O_(12)-Na_(0.5)Bi_(4.5)Ti_4O_(15) ceramics

Inter-growth bismuth layer-structured ferroelectrics（BLSFs）, Bi_4Ti_3O_（12）-Na_（0.5）Bi_（4.5）Ti_4O_（15）（BIT-NBT）, were successfully synthesized using the traditional solid-state reaction method. X-ray diffraction（XRD） Rietveld refinements were conducted using GSAS software. Good agreement and low residual are obtained. The XRD diffraction peaks can be well indexed into I2 cm space group. The inter-growth structure was further observed in the high-resolution TEM image. Dielectric and impedance properties were measured and systematically analyzed. At the temperature range 763-923 K（below T_c）, doubly ionized oxygen vacancies（OVs） are localized and the short-range hopping leads to the relaxation processes with an activation energy of 0.79-1.01 eV. Above T_c, the doubly charged OVs are delocalized and become free ones, which contribute to the long-range dc conduction. The reduction in relaxation species gives rise to a higher relaxation activation energy ~ 1.6 eV.

Theoretical analysis of the conversion from electrical into thermal energy in piezoelectric-conductive damping composites

Based on the principles of electrical conduction and transformation, a model was put forward for the electrical conversion of piezoelectric damping composites, and a related formula was derived. The results show that the best effect of conversion can be achieved by reducing the imaginary part of the impedance and matching the frequency. The optimal damping effect at a certain frequency requires resistance of conductive phase （R） satisfying the condition of R=I/（ωC）, but this condition may cause the damping effect at other frequencies to deviate away from the optimum condition. It is suggested that in order to make the damping effect more efficient and objective, frequency matching should be considered during the design of piezoelectric damping composites.

Health Monitoring of Induction Motor Using Electrical Signature Analysis

Induction motors have been widely used across industry,particularly with smaller loads and fixed speed services.Existing works focus on fault detection of induction motors without considering the shutdown time and production in industry.Therefore,this work aims to monitor the health conditions of the induction motor continuously through electrical signature analysis(ESA).The proposed technique is capable of predicting different kinds of faults,i.e.,rotor faults,stator phase imbalances,and supply cable faults at early stages.Moreover,ESA in real time is implemented.Thereafter,these current spectra were analyzed in frequency domain and compared with healthy current spectra.Performance evaluation is implemented by observing these spectra under different faulty conditions.A comparative study is made and analyzed through MATLAB simulations.

Influence of the gassing materials on the dielectric properties of air

Influence of the gassing materials, such as PA6, PMMA, and POM on the dielectric properties of air are investigated. In this work, the fundamental electron collision cross section data were carefully selected and validated. Then the species compositions of the air–organic vapor mixtures were calculated based on the Gibbs free energy minimization. Finally, the Townsend ionization coefficient, the Townsend electron attachment coefficient and the critical reduced electric field strength were derived from the calculated electron energy distribution function by solving the Boltzmann transport equation. The calculation results indicated that H;O with large attachment cross sections has a great impact on the critical reduced electric field strength of the air–organic vapor mixtures. On the other hand, the vaporization of gassing materials can help to increase the dielectric properties of air circuit breakers to some degree.

Improved Approximate Minimum Degree Ordering Method and Its Application for Electrical Power Network Analysis and Computation

Electrical power network analysis and computation play an important role in the planning and operation of the power grid,and they are modeled mathematically as differential equations and network algebraic equations.The direct method based on Gaussian elimination theory can obtain analytical results.Two factors affect computing efficiency:the number of nonzero element fillings and the length of elimination tree.This article constructs mapping correspondence between eliminated tree nodes and quotient graph nodes through graph and quotient graph theories.The Approximate Minimum Degree(AMD)of quotient graph nodes and the length of the elimination tree nodes are composed to build an Approximate Minimum Degree and Minimum Length(AMDML)model.The quotient graph node with the minimum degree,which is also the minimum length of elimination tree node,is selected as the next ordering vector.Compared with AMD ordering method and other common methods,the proposed method further reduces the length of elimination tree without increasing the number of nonzero fillings;the length was decreased by about 10%compared with the AMD method.A testbed for experiment was built.The efficiency of the proposed method was evaluated based on different sizes of coefficient matrices of power flow cases.

Numerical Analysis of Electrically Tunable Delay-Line with an SSB Modulator

By using an optical system simulator, we investigated the tunable delay-line with an optical SSB modulator and an optical fiber loop, where the delay can be controlled by the electric signal fed to the modulator.

A Dual-spline Approach to Load Error Repair in a HEMS Sensor Network

In a home energy management system(HEMS),appliances are becoming diversified and intelligent,so that certain simple maintenance work can be completed by appliances themselves.During the measurement,collection and transmission of electricity load data in a HEMS sensor network,however,problems can be caused on the data due to faulty sensing processes and/or lost links,etc.In order to ensure the quality of retrieved load data,different solutions have been presented,but suffered from low recognition rates and high complexity.In this paper,a validation and repair method is presented to detect potential failures and errors in a domestic energy management system,which can then recover determined load errors and losses.A Kernel Extreme Learning Machine(K-ELM)based model has been employed with a Radial Basis Function(RBF)and optimised parameters for verification and recognition;whilst a Dual-spline method is presented to repair missing load data.According to the experiment results,the method outperforms the traditional B-spline and Cubic-spline methods and can effectively deal with unexpected data losses and errors under variant loss rates in a practical home environment.

Identifying the occurrence time of an impending mainshock:a very recent case

The procedure by means of which the occurrence time of an impending mainshock can be identified by analyzing in natural time the seismicity in the candidate area subsequent to the recording of a precursory seismic electric signals（SES） activity is reviewed. Here, we report the application of this procedure to an MW5.4 mainshock that occurred in Greece on 17 November 2014. This mainshock（which is pretty rare since it is the strongest in that area for more than half a century） was preceded by an SES activity recorded on 27 July 2014, and the results of the natural time analysis reveal that the system approached the critical point（mainshock occurrence） early in the morning on 15 November 2014.

Dielectric barrier micro-plasma reactor with segmented outer electrode for decomposition of pure CO_(2)

Four coaxial cylinder dielectric barrier discharge micro-plasma reactors were designed for the noncatalytic decomposition of pure CO_(2) into CO and O_(2) at low temperature and ambient pressure.The influence of segmented outer electrodes on the electrical characteristics and the reaction performance was investigated.Experimental results indicated that the introduction of segmented outer electrodes can significantly promote the decomposition of CO_(2).Encouragingly,the highest conversion of 13.1% was obtained at an applied voltage of 18 kV,which was a substantial increase of 39.4% compared to the traditional device.Compared with other types of dielectric barrier discharge plasma reactors,the proposed segmented outer electrode micro-plasma reactor can give a higher CO_(2) conversion and acceptable energy efficiency.The increase in conversion can be attributed mainly to the enhanced corona discharge caused by the fringe effect at electrode edges,the increase in energy density and the increase in the number of micro-discharges.In addition,detailed electrical characterization was performed to reveal some trends in the electrical behavior of proposed reactors.

Equivalent circuit analysis of terahertz metamaterial filters

An equivalent circuit model for the analysis and design of terahertz （THz） metamaterial filters is presented.The proposed model,derived based on LMC equivalent circuits,takes into account the detailed geometrical parameters and the presence of a dielectric substrate with the existing analytic expressions for self-inductance,mutual inductance,and capacitance.The model is in good agreement with the experimental measurements and full-wave simulations.Exploiting the circuit model has made it possible to predict accurately the resonance frequency of the proposed structures and thus,quick and accurate process of designing THz device from artificial metamaterials is offered.

Analysis of the positive or negative lateral shift of the reflected beam in Otto configuration under grazing incidence

We investigate the lateral shift of a TM-polarized light beam reflected from Otto configuration under grazing incidence. It is found that the lateral shift is strongly dependent on the thickness of the air-gap layer. By employing the pole-null representation, we demonstrate that the lateral shift is closely related to the null of the reflection function. The numerical simulations for a Gaussian beam are performed to demonstrate the validity of our theoretical analvsis.

Fiber Bragg grating hydrophone with high sensitivity

A fiber Bragg grating （FBG） hydrophone with high sensitivity was demonstrated. This hydrophone used a rubber diaphragm and a copper hard core as the sensing element. To compensate the hydrostatic pressure, a capillary tube was fixed at the end of the hydrophone. Theoretical analysis of the acoustic pressure sensitivity was given in this letter. Experiments were carried out to test the frequency response of the hydrophone. The result shows that when the Young＇s modulus of the diaphragm is higher, a flatter frequency response will be obtained.

Design of resolution testing facility for ultraviolet imager

We present a resolution testing system of ultraviolet （UV） imager. In this system, an UV Czerny-Turner monochromator with a small f-number is designed to get more energy as an UV radiation source, and its stray light is rejected effectively by light traps. And UV diffuser is employed in order to get uniform light distribution on the resolving power test target. We also design a novel UV collimator which makes infinite UV testing targets. It can reduce the difficulty of optical design and the machining cost, and utilize UV energy at maximum extent. This facility has been applied in the imaging quality evaluation of the UV instrument, and the results accord with the theoretical analysis.

A compact T-branch beam splitter based on anomalous reflection in two-dimensional photonic crystals

We project a compact T-branch beam splitter with a micron scale using a two-dimensional （2D） photonic crystal （PC）. For TE polarization, one light beam can be split into two sub-beams along opposite directions. The propagating directions of the two splitting beams remain unchanged when the incident angle varies in a certain range. Coupled-mode theory is used to analyze the truncating interface structure in order to investigate the energy loss of the splitter. Simulation results and theoretical analysis show that choosing an appropriate location of the truncating interface （PC-air interface） is very important for obtaining high efficiency due to the effect of defect modes. The most advantage of this kind of beam splitter is being fabricated and integrated easily.

Investigation of biosensor built with photonic crystal microcavity

The ultra-compact biosensor based on the two-dimensional （2D） photonic crystal （PhC） microcavity is investigated. The performances of the sensor are analyzed theoretically using the Fabry-Perot （F-P） cavity model and simulated using the finite-difference time-domain （FDTD） method. The simulation results go along with the theoretical analysis.

The German Energiewende and its roll-out of renewableenergies： An economic perspective

This paper gives a short overview of the German Energiewende, i.e. the transition of a large and mostly thermal electricity system towards electricity generation from renewable energy source. It discusses both, the motivation of the transitions as future goals and current status. Furthermore, it gives an in-depth view into the changes in economic costs for society as well as electricity price effects, especially for average private households and industrial consumers. It also discusses the benefits of the promotion of renewable energies in Germany.

Improvement potential of today＇s WEEE recycling performance： The case of LCD TVs in Belgium

Waste of electrical and electronic equipment （WEEE） constitutes one of the most relevant waste streams because of the quantity and presence of valuable materials. However, there is limited knowledge on the resource potential of urban mining WEEE, as data on material composition, and the efficiency of current recycling treatments are still scarce. In this article, an evaluationof the recycling performance at a national level for one of the fastest growing e-waste streams： LCD TVs is carried out through the following four steps. Firstly, material characterisation is performed by means of sampling of the waste stream. Secondly, a material flow analysis is conducted by evaluating the separation performance of a recycling plant in Belgium..Thirdly, the recovered economic value and avoided environmental impact （EI） of the analysed recycling system is assessed. Finally, the potential of urban mining for Belgium is forecasted. The analysis shows that while recycling performance for ferrous metals and aluminium are relatively high; there is substantial room to better close the material loops for precious metals （PM） and plastics. PMs and plastics account for 66 % of the economic value in LCD TVs and 57% of the El. With the current, commonly applied recycling technology only one-third of the PM and housing plastics are recycled; meaning that for＇these material＇s, at a national level for Belgium, there is a potential for improvement that represents 3.3 million euros in 2016 and 6.8 million euros in 2025.