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After a brief presentation of the program éco21 and the framework of its monitoring and evaluation, this paper addresses the evaluation methodologies pertaining to two of the ten subprograms constituting éco21: Low Income Household ( éco- sociale) and Building Communal Areas ( communs d' immeubles). For these two subprograms, different options of enhanced engineering estimations-that will be used with a sample of projects-will enable to refine simple engineering estimations. (The terminology is inspired from the Directive 2006/32/EC) The aim is to drop the enhanced engineering methods later in favor of the 'improved' simple engineering estimations that are more efficient in time and cost. Billing analysis will be used systematically to double check the estimates and to evaluate the lifetime of the actions. First evaluation experiences: the results of the very first evaluation experiences for the two subprograms ( éco- sociale and communs d' immeubles) are presented. First feedback to program managers: the first pilot project of éco- sociale showed that the electrical power of the lights bulbs, which were replaced with more efficient ones, has an average value that is lower than the one expected before the implementation of the pilot project. However, for Building Communal Areas, the results from a sample of projects implemented during 2008 and 2009 show that the actual savings per project are higher than the expected savings. [ABSTRACT FROM AUTHOR]

Abstract: With the mature development of international carbon emissions trading market, the establishment of carbon trading market is an inevitable trend in China. This article think about the characteristics of China''s power industry, trying to study carbon emissions trading market mechanisms in the power sector, for providing a reliable basis to establish a national carbon trading market, so as to prepare for docking with the international market in the future. [Copyright &y& Elsevier]

This paper examines the South African economic sector's electricity consumption in response to fluctuations in electricity prices and economic output for the period 1993 to 2006. The results of the panel data analysis show that the industrial sector was the only one with statistically significant price elasticity over the study period. Further, economic output was a positive contributing factor to the industrial and commercial sectors (having high and significant coefficients). This is in contrast with the other three sectors, agriculture, transport and mining, whose electricity consumption was affected neither by price nor by their production. This anomaly is the result of both the relatively low and declining (in real terms) electricity prices over the study period, and the fact that the proportion of electricity cost to total cost is relatively small for the majority of sectors. There was therefore no major incentive to reduce electricity consumption and/or to be efficient. While these results explain, at least in part, the historical increases in electricity consumption, they may not hold for the period since 2008 (for which adequate data is not yet available), given the sharp increases in electricity prices recently experienced by the country. [ABSTRACT FROM AUTHOR]

This paper addresses the question of whether the evidence on positive relationship between environmental attitudes and household energy consumption in advanced post- industrial societies can be extended to emerging economies. In this study, we focused on electricity use and utilized multivariate regression to test the above hypothesis on a sample of residents of Óbuda (Budapest) in February 2011. The analysis suggests that the findings on the positive environmental attitude-behaviour relationship in advanced post-industrial societies can be extended to some (relatively affluent) communities in post-socialist societies. Our data also showed that the effects of housing type and demography are much larger compared to the effects of the attitudes. We emphasize that our findings do not provide evidence against the hypothesis on the interaction between the effects of societal culture and individual attitudes on pro-environmental behaviour. [ABSTRACT FROM AUTHOR]

Electricity production by bacterial communities enriched from wastewater sludge with lactate, succinate, N-acetyl-d-glucosamine (NAG), acetate, formate, and uridine were monitored in dual-chamber microbial fuel cells (MFCs). Stable electricity production was observed after 300 h for communities enriched from lactate, acetate, and formate, while communities enriched with succinate, NAG, and uridine stabilized only after 700 h. The average peak current densities and maximum power densities generated from bacterial consortia were significantly higher than those generated from pure cultures of Shewanella oneidensis MR-1. Microbial assemblages were analyzed by DGGE, and planktonic and anode-attached bacterial communities varied as a function of electron donors: Firmicutes, β-Proteobacteria, and Bacteroidetes dominated the planktonic bacterial communities while anode-attached communities consisted mainly of δ-Proteobacteria, β-Proteobacteria, and Firmicutes. Similar bacterial populations were enriched in MFCs fed with lactate, NAG, and uridine and with succinate, acetate, and formate. Cross-feeding experiments with different fuels indicated that enriched microbial consortia were able to utilize a variety of fuel sources and displayed considerable stability, efficiency, and robustness of power generation in comparison to pure cultures. In addition, characterizations of cultivated Shewanella strains suggested that DGGE analysis likely missed active members of exoelectrogenic populations. [ABSTRACT FROM AUTHOR]

Copyright of Listy Cukrovarnicke a Reparske is the property of VUC Praha a.s. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This paper analyzes the feasibility of optimally utilizing Ontario's grid potential for charging plug-in hybrid electric vehicles (PHEVs) during off-peak periods. Based an a simplified zonal model of Ontario's electricity-transmission network and a zonal pattern of base-load generation capacity from 2009 to 2025, an optimization model is developed to find the optimal, as well as maximum, penetrations of PHEVs into Ontario's transport sector. The results of this paper demonstrate that the present and projected electricity grid in Ontario can be optimally exploited for charging almost 6% of the total vehicles in Ontario or 12.5% of the vehicles in Toronto's transport sector by 2025; this corresponds to approximately 500 000 PHEVs that can be charged from the grid without any additional transmission or power-generation investments beyond those currently planned. [ABSTRACT FROM AUTHOR]

The article focuses on the integrated gasification combined cycle (IGCC), a clean-coal technology such as coal gasification via cleanup of gas produced and its benefit as gas or steam turbine combined cycles fuel to produce electricity. It states that IGCC involves heating coal, biomass, or coke to a high temperature with air and steam as well as oxygen. It presents government efforts to reduce emissions of greenhouse gases (GHGs). The advantages of IGCC thermal power plants are also discussed.

The air-core pulsed alternator has advantages in the application of pulsed power region, such as in electromagnetic launchers. The self-excitation and discharge processes in an air-core alternator are more complicated than traditional iron-core generators. In this paper, a mathematical model of an air-core pulsed alternator is built and several critical problems are analyzed, such as the conditions for successful self-excitation, the time needed for self-excitation, the waveforms of electromagnetic torque, discharge current and load voltage, and the compensation action during discharge, the effect of triggered angles, the rotational speed curve, and the energy reclaiming. Investigation of self-excitation and discharge processes in an air-core pulsed alternator is helpful for understanding the operation principle, predicting the performance, and analyzing and designing the system. [ABSTRACT FROM AUTHOR]

Although linear permanent-magnet generators (LPMGs) are widely used for converting wave energy into electrical energy, they suffer from large cogging force. The cogging force causes oscillatory output power, which shortens lifetime and increases the maintenance costs of the generators. To reduce this force in the generator, we have designed and simulated a three-phase LPMG for direct wave energy conversion and predicted its performance using the finite-element method. We studied the influence of different design parameters on the cogging force and minimized this force by varying the proposed parameters. The results obtained confirm a large reduction in the cogging force and an enhancement in the generator performance. [ABSTRACT FROM AUTHOR]

Copyright of Annals of 'Constantin Brancusi' University of Targu-Jiu. Engineering Series / Analele Universităţii Constantin Brâncuşi din Târgu-Jiu. Seria Inginerie is the property of Universitatea Constantin Brancusi din Targu-Jiu and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The article presents an examination of the process of scientific change. Drawing on the concept developed by American scientific historian Thomas Kuhn, the author explores how scientific change is preceded by conceptual change. The author examines the thirteenth century development of the compass in the Mediterranean region and related studies on magnetism conducted by French nobleman Petrus Peregrinus as well as the 18th century studies in electricity conducted by Parisian academic Charles Dufay in order to better understand the process of conceptual and scientific change.

The article presents a study which explores the differences of the electrical properties of screened residual cokes and coke formed in other means, in terms of particle size. The crystallographic structure of the selected cokes was defined using X-ray diffraction (XRD) measurements while differences of different cokes were also measured to determine the differences. Results show that small coke particles are subject to changes in coking practices and are formed in the middle of a coking battery.

Lightning-induced overvoltages have a considerable impact on the power quality of overhead distribution and telecommunications systems, and various models have been developed for the computation of the electromagnetic transients caused by indirect strokes. The most adequate has been shown to be the one proposed by Agrawal et al.; the Rusck model can be visualized as a particular case, as both models are equivalent when the lightning channel is perpendicular to the ground plane. In this paper, an extension of the Rusck model that enables the calculation of lightning-induced transients considering flashes to nearby elevated structures and realistic line configurations is tested against data obtained from both natural lightning and scale model experiments. The latter, performed under controlled conditions, can be used also to verify the validity of other coupling models and relevant codes. The so-called Extended Rusck Model, which is shown to be sufficiently accurate, is applied to the analysis of lightning- induced voltages on lines with a shield wire and/or surge arresters. The investigation conducted indicates that the ratio between the peak values of the voltages induced by typical first and subsequent strokes can be either greater or smaller than the unity, depending on the line configuration. [ABSTRACT FROM AUTHOR]

More precise modeling of the dynamic performance of grounding electrodes under lightning currents must include both the time-dependent nonlinear soil ionization and the frequency- dependent phenomena. These phenomena might have mutually opposing effects since the soil ionization effectively improves, while frequency-dependent inductive behavior impairs, the grounding performance. Modern approaches that take into account both phenomena are based on circuit theory that does not allow for accurate analysis of high-frequency behavior. This paper aims to further improve the understanding of the dynamic behavior of grounding electrodes under lightning currents by focusing on the following aspects: analyzing the validity domains of popular modeling approaches, based on circuit, transmission line, and electromagnetic theory; providing parametric analysis that takes into account both the propagation and soil ionization effects; analyzing simple formulas for surge characteristics; and comparing the modeling with experimental data. A model and a simple formula that combine the electromagnetic approach, suitable for high-frequency analysis, with the method that accounts for the soil ionization effects, recommended by the International Council on Large Electric Systems (CIGRE) and the IEEE Working Groups, are used for the parametric analysis. Both the model and the simple formula are verified by comparison with experimental results available in the literature. [ABSTRACT FROM AUTHOR]

We show that any lightning return-stroke model with specified longitudinal current distribution can be expressed, using the appropriate continuity equation, in terms of two current components, propagation current and corona current. For lumped-current-source (LCS)-type (transmission-line-type) models, the actual corona current is unipolar and directed radially out of the channel core, while for distributed-current-source (DCS)- type (traveling-current-source-type) models, it is also unipolar but directed into the channel core. The conversion between LCS and DCS return-stroke models alters the actual corona current (if any) of the model. A new formulation for LCS lightning return-stroke models is proposed using corona current and propagation current concepts. This formulation expresses the longitudinal current at height z′ as the channel-base current minus the overall longitudinal current change from ground surface to z′. Dynamics of lightning-channel corona sheath surrounding the thin channel core are examined based on ECS and DCS models. [ABSTRACT FROM AUTHOR]

The effects of finitely conducting ground on the signature of lightning-generated magnetic fields at ground level were evaluated by numerical solution of Sommerfeld's integrals. Results are presented for distances between 10 m to 1 km from the lightning channel and for ground conductivities in the range of 0.01 and 0.0001 S/m. The results obtained from the exact theory are compared with the predictions of two frequently used analytical approximations to Sommerfeld's equations. Based on that comparison, the limits of validity of these approximate theories are obtained. [ABSTRACT FROM AUTHOR]

Distributed nonlinear resistive elements are incorporated into an antenna theory (AT) model with fixed inductive loading (ATIL-F) to realistically model the current wave propagation along the lightning return-stroke channel (RSC). Resistive elements are considered as a nonlinear distributed load whose resistance is a function of both current and time. This is adopted from the numerical models of a spark channel and consequent shockwave from a lightning discharge, yielding a changing value of the channel radius from the base to the cloud along the RSC. It is demonstrated that the proposed model is more consistent with the nonlinear behavior of a lightning channel inferred from experimental physical observations. The model also satisfies most of the well-known characteristics of RSC, including the temporal and spatial current and charge distributions, some important features observed in radiated electromagnetic fields, and wave propagation speed profiles along the channel when compared with those predicted by the ATIL-F model. [ABSTRACT FROM AUTHOR]

We have compared current distributions along a vertical lightning channel above flat ground excited at its bottom by a lumped current source and electromagnetic field waveforms at different distances from the channel, calculated using the finite- difference time-domain method, for different lightning return- stroke electromagnetic models. The channel representations considered include a vertical, perfectly conducting wire surrounded by air (type 1), a vertical wire in air loaded by additional distributed series inductance L = 2.5 μH/m and distributed series resistance R = 0.5 Ω/m (type 2), a vertical, perfectly conducting wire embedded in dielectric of relative permittivity ϵr = 4 that occupies the entire half space (type 3), a vertical, perfectly conducting wire embedded in a 10-m-radius dielectric cylinder of ϵr = 400 surrounded by air (type 4), and a vertical wire embedded in a 10-m-radius cylinder of μr =5 and relative permeability μr = 5 surrounded by air (type 5). For the type-1 model, the speed of the current wave propagating along the lightning channel is essentially equal to the speed of light, v = c. For type-2, type-3, and type-5 models, v = 0.5c, and for the type-4 model, v = 0.7c. Models of types 2 and 5 reproduce the maximum number of characteristic features of electric and magnetic field waveforms observed at distances ranging from 1 to 200 km from natural lightning and at distances ranging from tens to hundreds of meters from rocket- triggered lightning. Modifications of type-2 and type-5 models in which distributed channel resistance is not uniform can reproduce all five characteristic features. The influence of lossy ground with conductivity as low as 0.1 mS/m on vertical electric and azimuthal magnetic fields within about d = 5 km is not significant. The initial peak of vertical electric field at d = 50 km for o = 0.1 mS/m is 20% smaller than that for σ = ∞. The 10%-90% rise time at d = 50 km is 5 μs for σ = 0.1 mS/m versus 1 μs for σ = ∞. [ABSTRACT FROM AUTHOR]

During various faults in a high voltage direct current (HVDC) system, the voltage gets reduced, which in turn results into commutation failure, which can deteriorate the availability of HVDC links and thus affect the performance of the power system. In this paper, efforts are made to ride through these faults and so to lower the effect of commutation failure on the power system, and the remedy is implemented by using a robust control algorithm which utilizes a new space vector modulation-based strategy. The validity and effectiveness of the control algorithm are verified by PSCAD/EMTDC-based simulation which shows that with the proposed control, the system can operate steadily, has the capability to restore steady state condition when short-circuit fault occurs, and is feasible technically and obvious in advantages. [ABSTRACT FROM AUTHOR]

We review the idea that domain boundaries, rather than domains, can carry information and act as memory devices. Domains are bulk objects; their large response to changing external fields is related to their change in volume, which implies the movement of domain boundaries. In many cases, the design of 'optimal' domain structures corresponds to 'optimal' domain boundaries with parameters such as the domain boundary mobility, pinning properties and the formation of specific boundaries such as curved boundaries or needle domains. This argument is enhanced further in this review: domain boundaries themselves can host properties which are absent in the bulk, they can be multiferroic, super- or semi-conductors while the matrix shows none of these properties. It is agued that multiferroic walls can be described formally as chiral whereby the chirality relates to state-vectors such as polarisation and magnetic moment and their (non-linear) coupling. Once such walls can be generated reliably, a new generation of devices with much higher storage density than ever produced before can be envisaged. [ABSTRACT FROM AUTHOR]

A scatterer is regarded as a one-port device, and an associated generalized transition matrix is defined uniquely to describe the relationships between the rotated tangential scattered field components and the rotated tangential incident field components on a specified reference surface. The reference surface can be moved to proper surfaces with regular shapes, or even be extended to include a group of scatterers with arbitrary shapes and different materials. Furthermore, scatterers connected with perfectly electric conducting (PEC) plates can also be handled with this one-port device model. Numerical results in two dimensions are provided to show that the generalized transition matrix is effective in analyzing large-scale scattering systems. [ABSTRACT FROM AUTHOR]

By an inductor for superficial hardening with 8kHz HF currents, having three coils: one for austenitizing and two for quasi-isothermal hardening of the bar steel surface, realised by simultaneous cooling with water, was studied the influence of the induction currents on the diffusion mechanism of the pearlitic transformation. The obtained microstructures indicates that the morphology of obtained pearlitic structures is not visible modified by the action of HF microcurrents but it is possible be favorised the formation of fine sorbitic and troostitic structure. [ABSTRACT FROM AUTHOR]

This study attempted to investigate the alternative conceptions that a group of 12 Lebanese students in a grade 9 class hold about electricity. It also attempted to evaluate learning outcomes of implementing in that class an inquiry-based module for the acquisition of conceptual understanding of basic concepts in electricity. Fourteen mostly subjective tests were administered throughout the implementation phase of the inquiry-based module to assess the evolution of participants’ conceptions. The instrument DIRECT (Version 1.0) focusing on conceptual understanding was used as a post-instructional test to measure acquisition of understanding. The findings revealed that most of the alternative conceptions reported in literature were found amongst the participants. Results of the post-testing showed that the implemented inquiry-based approach was successful in enhancing participants’ conceptual understanding of the targeted DC circuit concepts. [ABSTRACT FROM AUTHOR]

Abstract-Electrical power system robustness is defined as the intrinsic capacity of an electrical power system to maintain assigned disturbance levels when external conditions change. This paper compares two methods for estimating voltage dip severity: the critical distance method and the fault position method. Their differences are not linked to the type of network but to the type of results which we are searching for. This paper proposes a graphical color visualization of the during fault voltage matrices that immediately correlates dip severity with colors defined by a proper scale. New robustness indices are also proposed to synthesize bus performance in terms of affected and exposed areas. Numerical applications refer to real transmission and real distribution systems. [ABSTRACT FROM AUTHOR]

The dependence of microstructure, electrical properties, dielectric characteristics, and stability of conduction characteristics in ternary ZnO–V2O5–Mn3O4 system on the amount of Mn3O4 present in them was investigated. For all compositions studied, the microstructure of the ternary ZnO–V2O5–Mn3O4 system consisted of mainly ZnO grains and Zn3(VO4)2 as a secondary phase. The incorporation of Mn3O4 to the binary ZnO–V2O5 system was found to restrict abnormal grain growth of ZnO. The breakdown field in the electric field–current density characteristics increased from 175 to 4,635 V/cm with the increase of Mn3O4 amount. The ternary system doped with 0.5 mol% Mn3O4 exhibited the highest non-ohmic properties, in which the non-ohmic coefficient is 22.4 and the leakage current density is 0.22 mA/cm2. Furthermore, the sample doped with 0.5 mol% Mn3O4 was found to possess 0.43 × 1018/cm3 in donor density and 2.66 eV in barrier height. [ABSTRACT FROM AUTHOR]

Abstract: This paper presents an innovative voltage control scheme for a grid-connected wind farm. In wind power generation systems, operating conditions are changing continually by wind speed fluctuations and load changes. Therefore, a robust control mechanism is necessary. To enable a linear and robust control framework, the overall system is represented by a set of reduced-order linear systems that cover an operating range of interest determined by variations of the load. A control-design technique known as the linear quadratic regulator (LQR) can be conveniently utilized for multi-input multi-output systems. However, to make this approach applicable simultaneously to several linear systems, the LQR problem needs to be reformulated for finding a common Lyapunov function for the set of considered linear systems. This is accomplished by representing the underlying control optimization problem in terms of a system of linear-matrix-inequality (LMI) constraints and matrix equations that are simultaneously solved. The solution of LMI equations involves a form of quadratic Lyapunov function that not only gives the stability property of the controlled system but can also be used for achieving certain performance specifications. In addition, to make the control design applicable to realistic systems, with noise and disturbances in the measured signals, we consider a state observer. A candidate wind farm site on Vancouver Island, Canada, is conducted for simulation study. The proposed methodology is also flexible and readily applicable to larger wind farms of different configurations. [Copyright &y& Elsevier]

Abstract: In this paper, a new formulation for clearing reserve market in a deregulated environment with separated energy and reserve market is introduced. In the proposed method, reserve market is cleared such that the costs associated with capacity reservation, producing energy in real-time, opportunity cost of those units which are accepted in the energy market and backed down from the accepted values to participate in the reserve market are minimized. This optimization problem is formulated and solved using linear programming method. Finally, the proposed method is applied to a six units test system to examine the applicability and effectiveness of the proposed method. [Copyright &y& Elsevier]

Abstract: One common problem in drives applications is the presence of noise that corrupts the useful information in measurements such as of current, due to sensor imperfections. Digital low pass filters are a solution to the problem but they cannot cope when the useful information has time varying high frequency characteristics. In this paper, wavelet analysis, seldom used as yet in electric drives, is analysed and compared to classical methods. The key points of wavelet analysis are presented in a way that is appropriate for drives. Application of this new method to a typical practical current signal demonstrates the advantages and limitations of these methods over more conventional techniques. The true power of the wavelet transform is revealed when it is applied to a speed estimation problem where the rotor speed of a permanent magnet machine is modulated and coupled with high frequency components. [Copyright &y& Elsevier]

Abstract: This paper proposes a novel wavelet transform based relaying scheme for power transformer protection. The relay logic consists of two parts: disturbance detection based on first level high frequency details of the voltage signals only and fault discrimination using a power based directional signal derived from the first level high frequency details of both voltage and current signals. The logic is deterministic, computationally efficient, fast, secure and highly reliable. The operating time is 6ms, about 1/3rd of power frequency cycle (20ms). The scheme uses only the sign of the directional signals, rather than the difference in their magnitudes, hence it can work reliably in the presence of transformer tap variation, fault resistance and CT saturation. The validity of the proposed logic was exhaustively tested by simulating various types of internal and external faults, energization conditions and load variations on a 132kV system modeled in ATP/EMTP with a 31.5 MVA, 132/33kV, Y–Δ transformer. The proposed logic was able to correctly discriminate between internal faults, external faults and non-fault disturbances for all the 880 test cases. [Copyright &y& Elsevier]

Chiral metal-organic frameworks (MOFs) have attracted a growing interest for their potential use in energy technologies, asymmetric catalysis, chiral separation, and on a more basic level, the creation of new topologies in inorganic materials. The current paper is the first report on a peptide-based MOF, a metal peptide framework (MPF), constructed from an oligovaline peptide family developed earlier by our group (Mantion, A.; et al. Macromol. Biosci. 2007, 7, 208). We have used a simple oligopeptide, Z-(L-Val)2-L-Glu(OH)-OH, to grow porous copper and calcium MPFs. The MPFs form thanks to the self-assembling properties of the peptide and specific metal-peptide and metal-ammonia interactions. They are stable up to ca. 250 °C and have some internal porosity, which makes them a promising prototype for the further development of MPFs. [ABSTRACT FROM AUTHOR]

We study the effect of defects in the Mott insulator phase of ultracold atoms in an optical lattice on the dynamics of resonant electronic excitations. These excitations can be described analogous to Frenkel excitons in solids and form polaritons, when coupled to an optical resonator. Defects, which are empty sites in a singly occupied Mott insulator state or singly occupied sites for a filling factor two, change the exciton dynamics. We show that vacancies behave like hard sphere scatterers, while singly occupied sites in a doubly filled region generate either attractive or repulsive interaction potentials. We suggest cavity polaritons as tools which detect such defects and show how the scattering can be controlled by changing the exciton-photon detuning. In the case of aspherical individual lattice sites, we calculate the effective scattering potential as a function of the cavity photon polarization direction which exhibits a crossover from a repulsive into an attractive potential and should give a clearly observable signal. [ABSTRACT FROM AUTHOR]

Dielectric anisotropy, memory state and diffraction efficiency properties of E7 liquid crystal and AP-SPAB7 doped liquid crystal composite are investigated by dielectric and electrical conductivity properties. The liquid crystals exhibit dielectrically controlled positive dielectric anisotropy (p-type Δɛ) with the critical frequency transition to negative dielectric anisotropy (n-type Δɛ) behavior. The AP-SPAB7 doping does not change the memory state properties of LC, while the doping changes dependency of dielectric anisotropy on applied voltage. The diffraction efficiency is significantly enhanced in the AP-SPAB7 doped LC. The refractive index modulation values of the E7 and E7/AP-SPAB7 were found to be and , respectively. The AP-SPAB7 doping increases the refractive index modulation of E7 LC. [Copyright &y& Elsevier]

Abstract: Wind generation is substantially increasing its share in the electricity generation portfolio in many countries. In the case of Spain, it can more than double in the next 4 years, reaching a 20GW level. To become competitive in a liberalized market, wind energy reliability requirements should be guaranteed, so storage systems are being considered to avoid the impact of the lack of adequate winds on the electricity generation process. This paper, assuming different scenarios for the electricity markets and the wind farm operation, analyzes the minimum requirements on energy efficiency of a storage system based on the use of hydrogen as energy vector to become economically competitive for each of those scenarios. Simulation of a wind park with such a buffer system for different operation scenarios shows a direct dependence of the economical profit on the energy efficiency of this hydrogen backup system. A direct conclusion of the study is the necessity for an improvement of the currently available values of the efficiency of the subsystems that compose the hydrogen buffer. These improvements seem to be possible in the short term when attending to the current research efforts. [Copyright &y& Elsevier]

The paper describes an experimental analysis on the effect of cathode flow stoichiometry on the electrical performance of a PEMFC stack. The electrical power output of a PEMFC stack is influenced by several independent variables (factors). In order to analyse their reciprocal influence, an experimental design methodology was adopted in a previous experimental session, to determine which factors deserve particular attention. In this work, a further experimental analysis has been carried out on a very significant factor: cathode stoichiometry. Its effects on the electrical power of the PEMFC stack have been investigated. The tests were performed on a 3. 5kWel ZSW stack using the GreenLight GEN VI FC Test Station. The stack characteristics have been obtained running a predefined loading pattern. Some parameters were kept constant during the tests: anode and cathode inlet temperature, anode and cathode inlet relative humidity, anode stoichiometry and inlet temperature of the cooling water. The experimental analysis has shown that an increase in air stoichiometry causes a significant positive effect (increment) on electric power, especially at high-current density, and up to the value of 2 stoichs. These results have been connected to the cathode water flooding, and a discussion was performed concerning the influence of air stoichiometry on electrode flooding at different levels of current density operation. [Copyright &y& Elsevier]

An induction charge detector yields the net charge and the time of flight of a particle. The unique ability to independently measure these two parameters sets apart this rather simple detection technique. The main shortcoming of this instrument is its high charge detection limit, resulting from the intrinsic noise of the detector electronics and the low signal associated with the charge to measure. The goal of the present work is to lower the detection limit of this detector. This article describes an induction charge detector whose main novelty is a sequence of aligned cylindrical electrodes for measuring the charge of a particle n times. In a time domain analysis, this feature reduces both the detection limit and the standard error of the charge measurement by factors of 2 and n. More importantly, sensing stages could be added to arbitrarily lower the detection limit in a frequency domain analysis. [ABSTRACT FROM AUTHOR]

Oxide charge on the sidewalls of SiO2 embedded silicon wires with 20×20 nm2 cross section is shown to influence the Schottky barrier height for Pd2Si/Si junctions positioned on the end surfaces of the wires. Compared with results on planar silicon surfaces, the electron barrier height is 0.3 eV lower for wires investigated as fabricated. By increasing the oxide charge through irradiation by ultraviolet light, the electron barrier decreases by an additional 0.15 eV and the hole barrier correspondingly increases by about the same amount. The phenomenon is explained by assuming an oxide charge density in the range of 1012 cm-2. [ABSTRACT FROM AUTHOR]

The paper deals with internal faults in large power transformers. The explanation of such faults is followed by the description of an analytical method proposed for the calculation of the power flow during an interturn fault, including the current supplied by the power grid, the current in a group of short-circuited turns and the current in the spot of short-circuiting. The currents are calculated for cylindrical windings as a function of the fault area and its location with respect to the winding height for different structural configurations. An appropriate modification of Rogowski's coefficient is introduced. Computational results based on theoretical considerations are shown to be in good agreement with measurements carried out on a realistic model. [ABSTRACT FROM AUTHOR]

Recently it has been shown that electrical energy can be harvested from marine sediments, simply by connection of an electrode (anode) in anaerobic marine sediments to an electrode in the aerobic zone above the sediments. We have now shown that similar applications are available in sludge treatment. Using a reactor with graphite foil electrodes in an aerated aerobic and anaerobic sludge zone, electrical current was generated, and enhanced when an additional organic substrate (acetate) was added. Electron microscopy, x-ray diffraction, and PCR examination of the anode surface showed no surface colonization and no increase in Geobacter relative to a control, indicating that microbial use of the anode as an electron acceptor was indirect through the use of redox mediators. Given the demonstration of electricity generation from sludge, the potential for similar applications, using other organic waste sources, is evaluated. [ABSTRACT FROM AUTHOR]

Focuses on John Walsh's research on electric fish, carried out between 1772 and 1775. Significance of the research in demonstrating the possible involvement of electricity in animal physiology; Reason for the neglect by science historians on the contributions of Walsh in science research; Details on Walsh's experiment on the production of a spark from a discharge of the electric eel.

Discusses proposed federal legislation on electricity research and development (R&D) in the United States. Information on decline in electric power research; Reasons for continuing private-sector, public-benefit collective R&D; Challenge to state commissions and the National Association of Regulatory Commissioners.

We developed a cryogenic system on a rotating table that achieves sub-Kelvin conditions. The cryogenic system consists of a helium sorption cooler and a pulse tube cooler in a cryostat mounted on a rotating table. Two rotary-joint connectors for electricity and helium gas circulation enable the coolers to be operated and maintained with ease. We performed cool-down tests under a condition of continuous rotation at 20 rpm. We obtained a temperature of 0.23 K with a holding time of more than 24 h, thus complying with catalog specifications. We monitored the system's performance for four weeks; two weeks with and without rotation. A few-percent difference in conditions was observed between these two states. Most applications can tolerate such a slight difference. The technology developed is useful for various scientific applications requiring sub-Kelvin conditions on rotating platforms. [ABSTRACT FROM AUTHOR]

Se presentan noticias que tratan de la economía latinoamericana. Se comenzó en agosto de 1961 la Reunión Extraordinaria del Consejo Interamericano Económico y Social. Se estudiaban en México los problemas latinoamericanos de energía eléctrica. Brasil y Chile habían decidido elevar su comercio recíproco. El Banco Interamericano de Desarrollo concedió un préstamo para el desarrollo económico de las provincias argentinas. Se estableció en Paraguay un Banco de Fomento.

The article discusses whether Benjamin Franklin invented the lightning rod prior to his experiments with electricity. The author discusses how Franklin had proposed the use of rods mounted on buildings to test electricity in letters to his friend Peter Collinson prior to his experiments using a kite. Franklin's proposal inspired electricity experiments by French physicists. A letter from assessor Jacques de Romas suggests Franklin conducted his kite experiment in the summer of 1752. Franklin built a lightning rod on his home later that year. An item in an edition of the publication "Poor Richard's Almanac" revealed that Franklin had established instructions for the construction of lightning rods prior to the work of physicist J.H. Winkler.

The unplugged electronic display were fabricated and investigated in this study. The electro phoretic display (EPD) and solar cell device were laminated as an ultra thin structure, leading to a flexible, light and unbroken characteristics. Also, surface engineering for dust-proof and water-proof was performed for product application. Furthermore, the electricity generated by solar cells can support the operation of EPD device by maximum power point tracking (MPPT) technology. [ABSTRACT FROM AUTHOR]