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Power Generation (power + generation)

Distribution by Scientific Domains
Engineering42%
Chemistry23%
Polymers and Materials Science7%
Life Sciences7%
Earth and Environmental Science7%
Business, Economics, Finance and Accounting4%
2 Other Domains10%
Distribution within Engineering
Power Technology & Power Engineering66%
General & Introductory Mechanical Engineering9%

Kinds of Power Generation

  • electric power generation
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    Terms modified by Power Generation

  • power generation system
    		•
  • power generation technology
    		•

    Selected Abstracts

    Power Generation and Electrochemical Analysis of Biocathode Microbial Fuel Cell Using Graphite Fibre Brush as Cathode Material

    FUEL CELLS, Issue 5 2009
    S.-J. You
    Abstract To improve cathodic efficiency and sustainability of microbial fuel cell (MFC), graphite fibre brush (GFB) was examined as cathode material for power production in biocatalysed-cathode MFC. Following 133-h mixed culturing of electricity-producing bacteria, the MFC could generate a reproducible voltage of 0.4,V at external resistance (REX) of 100,,. Maximum volumetric power density of 68.4,W,m,3 was obtained at a current density of 178.6,A,m,3. Upon aerobic inoculation of electrochemically active bacteria, charge transfer resistance of the cathode was decreased from 188 to 17,, as indicated by electrochemical impedance spectroscopy (EIS) analysis. Comparing investigations of different cathode materials demonstrated that biocatalysed GFB had better performance in terms of half-cell polarisation, power and Coulombic efficiency (CE) over other tested materials. Additionally, pH deviation of electrolyte in anode and cathode was also observed. This study provides a demonstration of GFB used as biocathode material in MFC for more efficient and sustainable electricity recovery from organic substances. [source]

    A comparative study on cost and life-cycle analysis for 100,MW very large-scale PV (VLS-PV) systems in deserts using m-Si, a-Si, CdTe, and CIS modules

    PROGRESS IN PHOTOVOLTAICS: RESEARCH & APPLICATIONS, Issue 1 2008
    Masakazu Ito
    Abstract This paper is a study of comparisons between five types of 100,MW Very Large-Scale Photovoltaic Power Generation (VLS-PV) Systems, from economic and environmental viewpoints. The authors designed VLS-PV systems using typical PV modules of multi-crystalline silicon (12·8% efficiency), high efficiency multi-crystalline silicon (15·8%), amorphous silicon (6·9%), cadmium tellurium (9·0%), and copper indium selenium (11·0%), and evaluated them by Life-Cycle Analysis (LCA). Cost, energy requirement, and CO2 emissions were calculated. In addition, the authors evaluated generation cost, energy payback time (EPT), and CO2 emission rates. As a result, it was found that the EPT is 1·5,2·5 years and the CO2 emission rate is 9,16,g-C/kWh. The generation cost was 11,12 US Cent/kWh on using 2 USD/W PV modules, and 19,20 US Cent/kWh on using 4 USD/W PV module price. Copyright © 2007 John Wiley & Sons, Ltd. [source]

    Mechanical Response Analysis and Power Generation by Single-Cell Stretching

    CHEMPHYSCHEM, Issue 4 2005
    Alexandre Micoulet Dr.
    Abstract To harvest useful information about cell response due to mechanical perturbations under physiological conditions, a cantilever-based technique was designed, which allowed precise application of arbitrary forces or deformation histories on a single cell in vitro. Essential requirements for these investigations are a mechanism for applying an automated cell force and an induced-deformation detection system based on fiber-optical force sensing and closed loop control. The required mechanical stability of the setup can persist for several hours since mechanical drifts due to thermal gradients can be eliminated sufficiently (these gradients are caused by local heating of the cell observation chamber to 37,°C). During mechanical characterization, the cell is visualized with an optical microscope, which enables the simultaneous observation of cell shape and intracellular morphological changes. Either the cell elongation is observed as a reaction against a constant load or the cell force is measured as a response to constant deformation. Passive viscoelastic deformation and active cell response can be discriminated. The active power generated during contraction is in the range of Pmax=10,16Watts, which corresponds to 2500 ATP molecules,s,1at 10 kBT/molecule. The ratio of contractive to dissipative power is estimated to be in the range of 10,2. The highest forces supported by the cell suggest that about 104molecular motors must be involved in contraction. This indicates an energy-conversion efficiency of approximately 0.5. Our findings propose that, in addition to the recruitment of cell-contractile elements upon mechanical stimulation, the cell cytoskeleton becomes increasingly crosslinked in response to a mechanical pull. Quantitative stress,strain data, such as those presented here, may be employed to test physical models that describe cellular responses to mechanical stimuli. [source]

    Fabrication and Application of an Oxide Thermoelectric System

    INTERNATIONAL JOURNAL OF APPLIED CERAMIC TECHNOLOGY, Issue 4 2007
    Ryoji Funahashi
    A plate-shaped thermoelectric module was prepared using 140 pairs of p -type Ca3Co4O9 (Co-349) and n -type LaNiO3 (Ni-113) bulks. The hot-pressed thermoelectric oxide bulks were connected with an Ag paste, incorporating oxide powder, and Ag sheets. The module's open-circuit voltage increases with increasing hot-side temperature (TH) and reaches 4.5 V at a TH of 1072 K in air. No deterioration in output power was seen when power generation was carried out 10 times at a TH of 723 K with intermediate cooling to room temperature. The module was successfully used to charge a lithium-ion battery in a mobile phone. Thermoelectric modules composed of p -type Co-349 and n -type CaMnO3 (Mn-113) bulks, which have a pipe shape, were constructed using Ag electrodes and stainless-steel tubes. The devices were connected with the stainless-steel tube coated with ZrO2 by thermal spray using a dielectric paste composed of silica glass and iron oxide. Power generation was carried out in flame by combustion of natural gas. Water flowed inside the stainless-steel tube for cooling. One module consisting of 54 pairs of legs can generate 1.5 V, 0.28 W, and steam simultaneously by installing in an instantaneous water heater. Power generation was carried out four times with intermediate cooling. Deterioration in the open-circuit voltage of the module was not observed after the fourth combustion. [source]

    Power generation from coal and biomass based on integrated gasification combined cycle concept with pre- and post-combustion carbon capture methods

    ASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 6 2009
    Calin-Cristian Cormos
    Abstract Gasification technology is a process in which solid fuel is partially oxidised by oxygen and steam/water to produce a combustible gas called syngas (mainly a mixture of hydrogen and carbon monoxide). Syngas can be used either for power generation or processed to obtain various chemicals (hydrogen, ammonia, methanol, etc.). This article evaluates the possibilities of solid fuel decarbonisation by capturing carbon dioxide resulted form thermo-chemical conversion of solid fuel using gasification. Evaluation is focused on power generation technology using syngas produced by solid fuel gasification (so-called integrated gasification combined cycle,IGCC). Case studies analysed in the article are using a mixture of coal and biomass (sawdust) to produce around 400 MW electricity simultaneously with capturing about 90% of the feedstock carbon. Various carbon dioxide capture options (post- and pre-combustion) are compared with situation of no carbon capture in terms of plant configurations, energy penalty, CO2 emissions, etc. Plant options are modelled using ChemCAD, and simulation results are used to assess the plant performances. Plant flexibility and future improvements are also discussed. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd. [source]

    Prescribing Flood Regimes to Sustain Riparian Ecosystems along Meandering Rivers

    CONSERVATION BIOLOGY, Issue 5 2000
    Brian D. Richter
    By managing river flows for water supplies and power generation, water management agencies have inadvertently caused considerable degradation of riverine ecosystems and associated biodiversity. New approaches for meeting human needs for water while conserving the ecological integrity of riverine ecosystems are greatly needed. We describe an approach for identifying the natural flooding characteristics that must be protected or restored to maintain riparian ( floodplain) ecosystems along meandering rivers. We developed a computer model to simulate flood-driven changes in the relative abundance of riparian patch types along the Yampa River in Colorado ( U.S.A.). The model is based on research suggesting that the duration of flooding at or above 209 m3 per second (125% of bankfull discharge) is particularly important in driving lateral channel migration, which is responsible for initiating ecological succession in the Yampa's riparian forest. Other hydrologic variables, such as the magnitude of annual peak flows, were not as strongly correlated with lateral channel migration rates. Model simulations enabled us to tentatively identify a threshold of alteration of flood duration that could lead to substantial changes in the abundance of forest patch types over time should river flows be regulated by future water projects. Based on this analysis, we suggest an ecologically compatible water management approach that avoids crossing flood alteration thresholds and provides opportunity to use a portion of flood waters for human purposes. Recommended improvements to the Yampa model include obtaining additional low-elevation aerial photographs of the river corridor to enable better estimation of channel migration rates and vegetation changes. These additional data should greatly improve the model's accuracy and predictive capabilities and therefore its management value. Resumen: La composición y estructura de ecosistemas ribereños están fuertemente ligadas a la variabilidad hidrológica natural. Al manejar el flujo de ríos para abastecer agua y generar energía, las agencias de manejo de agua han causado inadvertidamente una degradación considerable de los ecosistemas ribereños y la biodiversidad asociada a ellos. Se necesitan nuevas estrategias para satisfacer las necesidades humanas de agua al mismo tiempo que se conserva la integridad de los ecosistemas ribereños. Describimos una estrategia para identificar las características de inundaciones naturales que deben ser protegidas o restauradas para mantener ecosistemas riparios ( planicies de inundación) a lo largo de ríos sinuosos. Desarrollamos un modelo de computadora para simular los cambios causados por inundaciones en la abundancia relativa de tipos de parche ripario a lo largo del río Yampa, en Colorado ( Estados Unidos de Norteamérica). Este modelo se basa en investigación que sugiere que la duración de la inundación a, o mayor a, 209 m3 por segundo (125% de descarga del banco lleno a su capacidad) es particularmente importante en la conducción de la migración de canales laterales, lo cual es responsable de la iniciación de la sucesión ecológica en el bosque ripario del río Yampa. Otras variables hidrológicas, como lo es la magnitud del pico de los flujos anuales no estuvieron tan fuertemente correlacionadas con las tasas de migración lateral de canales. Las simulaciones del modelo nos permitieron identificar límites tentativos de alteración de la duración de la inundación que podrían conducir a cambios sustanciales en la abundancia de tipos de parches forestales en el tiempo si los flujos de los ríos son regulados en proyectos de agua futuros. En base a este análisis, sugerimos una estrategia de manejo de agua ecológicamente compatible que evita sobrepasar los límites de alteración de las inundaciones y provee la oportunidad de usar una porción del agua de las inundaciones para fines humanos. Las recomendaciones de mejoras al modelo del río Yampa incluyen la necesidad de obtener fotografías aéreas de baja elevación adicionales del corredor del río, que permitan una mejor estimación de las tasas de migración de los canales y los cambios en la vegetación. Estos datos adicionales deberán mejorar en gran medida la precisión del modelo y sus capacidades predictivas y, por lo tanto, su valor de manejo. [source]

    Experimental study of a doubly-fed rotary frequency converter

    ELECTRICAL ENGINEERING IN JAPAN, Issue 4 2010
    Yasutoshi Takemoto
    Abstract Wind power generation using an unlimited, natural energy has been getting attention regarding environmental issues in recent years, and the installed capacity of wind power generation system is increasing at a rapid pace, resulting in deterioration of power quality especially in frequency and voltage. This fact will be a big problem in restricting large capacity of wind farms. This paper proposes a new frequency converter: rotary frequency converter (RFC) to moderate the electric output from wind generation, which is to be installed between a set of wind generators and a grid, providing a smoothed electric output, promoting the wind power generation introduction. This mainly consists of a synchronous machine and the adjustable-speed machine. Independent controls of input/output voltage, active power, and reactive power offer electrical separation between the two networks. Experimental study of a prototype model and its characteristics, especially dynamic control, is discussed in this paper. © 2009 Wiley Periodicals, Inc. Electr Eng Jpn, 170(4): 26,34, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20922 [source]

    Proposal and development of radial air-gap coreless generator suitable for small wind turbine used in urban area

    ELECTRICAL ENGINEERING IN JAPAN, Issue 1 2009
    Toshiyuki Takahashi
    Abstract Independent distributed power generation using small wind turbines is becoming more widespread as wind power generation increases. Installation of small wind turbines in densely populated urban areas is not only useful from the viewpoint of extracting wind power sources in weak-wind areas but also for making renewable energy easier to access when power supplies are closer to consumers. It is from this point of view that the authors proposed "urban wind power generation" using a collective system with a number of small vertical wind turbines, and have developed a suitable generator for low-speed vertical wind turbines such as a Savonius windmill. Based on a standard coreless generator, the proposed generator is designed to make the direction of the magnetic flux radial in order to install the magnets and coils on the outer end of the generator. The change of magnet composition and flux direction maximizes the speed of the flux change and output voltage within a limited space. With the above configuration, the power of the proposed generator is independent of the diameter. In this report, the authors describe and evaluate the fundamental performance of a prototype of the proposed generator. Based on the experiments, a maximum output power of 283 W was obtained. The obtained starting torque is small enough to begin rotation under weak wind conditions of no more than 1 m/s. Therefore, it is clear that the proposed "radial" coreless generator is suitable for self-starting and producing high power at low wind speed. © 2009 Wiley Periodicals, Inc. Electr Eng Jpn, 167(1): 26, 34, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20695 [source]

    Numerical simulation on operation of closed-loop experimental facility with subsonic MHD generator

    ELECTRICAL ENGINEERING IN JAPAN, Issue 1 2008
    Hidemasa Takana
    Abstract The operating characteristics and operation procedure of the closed-loop experimental facility under subsonic power generation have been investigated by means of time-dependent quasi-one-dimensional numerical simulations. Two ways of operation for subsonic power generation were found: (1) subsonic operation both under nonpower and power generation and (2) supersonic operation under nonpower generation and subsonic operation under power generation. For operation (1), Mach number at channel inlet decreases to ,0.6, therefore it is required to generate plasma under this Mach number. On the other hand, if the plasma cannot be generated, operation (2) needs to be carried out. In this case, a shock wave appears in the generator channel, then the influence of a large pressure change and a vibration caused by a shock wave in the generator channel needs to be considered. © 2008 Wiley Periodicals, Inc. Electr Eng Jpn, 163(1): 25,33, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20399 [source]

    Transient stability simulation of wind generator expressed by two-mass model

    ELECTRICAL ENGINEERING IN JAPAN, Issue 3 2008
    Yoshikazu Shima
    Abstract Recently, wind power generation is increasing worldwide. In wind power stations, induction machines are mostly used as generators. Since induction generators have a stability problem similar to the transient stability of synchronous machines, it is important to analyze the transient stability of power systems including wind generators. Although there have been some reports analyzing the transient stability problem, wind turbine and wind generator are, in most cases, modeled as a one-mass shaft system having total inertia constant. This paper presents simulation analyses of transient stability of power system including induction generator which is expressed by a two-mass shaft model and analyzes an effect of shaft system modeling on the transient stability characteristics. Simulations are performed by PSCAD/EMTDC in this study. © 2007 Wiley Periodicals, Inc. Electr Eng Jpn, 162(3): 27,37, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20394 [source]

    Analysis of lightning surge propagation in wind farm

    ELECTRICAL ENGINEERING IN JAPAN, Issue 2 2008
    Yoh Yasuda
    Abstract Wind power generation is expected to become more important in future distribution systems. Although several prospective reports such as IEC 61400-24 and NREL SR-500-31115 indicate an insulation scheme and grounding design for lighting protection, there still seems to be too few investigations on the problems. This paper therefore discusses lightning surge analysis using a wind farm model with 2 or 10 ideal wind turbines. Changing parameters such as grounding resistance and lightning strike points, several cases were studied. As a result of the analysis using digital simulator ARENE, it is clear that the surge tends to propagate toward the end of a distribution line in a wind farm and there is the possibility of insulation accidents at the other wind turbines when lightning attacks a wind turbine. © 2007 Wiley Periodicals, Inc. Electr Eng Jpn, 162(2): 30, 38, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20364 [source]

    Transient response of closed-loop MHD experimental facility

    ELECTRICAL ENGINEERING IN JAPAN, Issue 1 2007
    Hidemasa Takana
    Abstract Transient responses of a closed-loop MHD experimental facility from nonpower generation to power generation have been investigated by means of time-dependent quasi-one-dimensional numerical simulations. For the long-time continuous power generation experiment, the time required to obtain the steady state for the power generation is estimated to be approximately 20 hours. By increasing the electrical input power to the heater as an exponential function of time, the temperature increment of ceramics can be moderated. When the duration of the experiment is around 10 minutes, argon gas temperature at the exit of the heater hardly changes because of the large heat capacity of structure materials. It is found that the fluid disturbances are induced at the instant of the power generation and they propagate as they repeatedly reflect at the sudden change of duct shape. Since all of the induced disturbances attenuate approximately 0.4 second after the power generation, the time scale that the disturbances exist in the facility is estimated to be 1 second at most. © 2006 Wiley Periodicals, Inc. Electr Eng Jpn, 158(1): 46,52, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20237 [source]

    Analysis of effect of electrolyte types on electrokinetic energy conversion in nanoscale capillaries

    ELECTROPHORESIS, Issue 3 2010
    Reiyu Chein
    Abstract An analytical study on the effect of electrolyte types on the electrokinetic energy conversion is presented using nanoscale cylindrical capillary, which is either positively or negatively charged. The sign of surface charge determines the role and concentration magnitude of ions in the capillary and the energy conversion performance. Our study shows that the electrokinetic energy conversion performance (maximum efficiency, pressure rise and streaming potential) are approximately identical for 1:1 (KCl), 2:1 (CaCl2) and 3:1 (LaCl3) electrolytes when capillary is positively charged. For negatively charged capillary, energy conversion performance degrades significantly with the increase of counter-ion valence. For both positively and negatively charged capillaries, higher maximum efficiency can be resulted in low bulk concentration and surface charge density regimes. However, high maximum pressure rise generation for the pumping is found in the low bulk concentration and high surface charge density regimes. For the electric power generation, higher maximum streaming potential is found when both bulk concentration and surface charge density are low. [source]

    Optimal production cost of the power producers with linear ramp model using FDR PSO algorithm

    EUROPEAN TRANSACTIONS ON ELECTRICAL POWER, Issue 2 2010
    M. Anitha
    Abstract In practice, the power producers have to be rescheduled for power generation beyond their power limits to meet vulnerable situations like credible contingency and increase in load conditions. During this process, the ramping cost is incurred if they violate their permissible elastic limits. In this paper, optimal production costs of the power producers are computed with ramping cost considering stepwise and piecewise linear ramp rate limits using fitness distance ratio particle swarm optimization (FDR PSO) algorithm. Transient stability constraints are also considered while formulating the optimal power flow (OPF) problem as additional rotor angle inequality constraints. The proposed algorithm is demonstrated on a practical 39 bus New England and 62 bus Indian Utility system with different case studies. Copyright © 2008 John Wiley & Sons, Ltd. [source]

    Improved genetic algorithm for multi-objective reactive power dispatch problem

    EUROPEAN TRANSACTIONS ON ELECTRICAL POWER, Issue 6 2007
    D. DevarajArticle first published online: 12 JAN 200
    Abstract This paper presents an improved genetic algorithm (GA) approach for solving the multi-objective reactive power dispatch problem. Loss minimization and maximization of voltage stability margin are taken as the objectives. Maximum L-index of the system is used to specify the voltage stability level. Generator terminal voltages, reactive power generation of capacitor banks and tap changing transformer setting are taken as the optimization variables. In the proposed GA, voltage magnitudes are represented as floating point numbers and transformer tap-setting and reactive power generation of capacitor bank are represented as integers. This alleviates the problems associated with conventional binary-coded GAs to deal with real variables and integer variables with total number of permissible choices not equal to 25. Crossover and mutation operators which can deal with mixed variables are proposed. The proposed method has been tested on IEEE 30-bus system and is compared with conventional methods and binary-coded GA. The proposed method has produced the loss which is less than the value reported earlier and is well suitable for solving the mixed integer optimization problem. Copyright © 2007 John Wiley & Sons, Ltd. [source]

    Energy Harvesting with Single-Ion-Selective Nanopores: A Concentration-Gradient-Driven Nanofluidic Power Source

    ADVANCED FUNCTIONAL MATERIALS, Issue 8 2010
    Wei Guo
    Abstract Inspired by biological systems that have the inherent skill to generate considerable bioelectricity from the salt content in fluids with highly selective ion channels and pumps on cell membranes, herein, a fully abiotic single-pore nanofluidic energy-harvesting system that efficiently converts Gibbs free energy in the form of a salinity gradient into electricity is demonstrated. The maximum power output with the individual nanopore approaches ,26,pW. By exploiting parallelization, the estimated power density can be enhanced by one to three orders over previous ion-exchange membranes. A theoretical description is proposed to explain the power generation with the salinity-gradient-driven nanofluidic system. Calculation results suggest that the electric-power generation and its efficiency can be further optimized by enhancing the surface-charge density (up to 100,mC m,2) and adopting the appropriate nanopore size (between 10 and 50,nm). This facile and cost-efficient energy-harvesting system has the potential to power biomedical tiny devices or construct future clean-energy recovery plants. [source]

    Undulatory fish swimming: from muscles to flow

    FISH AND FISHERIES, Issue 2 2006
    Ulrike K. Müller
    Abstract Undulatory swimming is employed by many fish for routine swimming and extended sprints. In this biomechanical review, we address two questions: (i) how the fish's axial muscles power swimming; and (ii) how the fish's body and fins generate thrust. Fish have adapted the morphology of their axial musculature for high power output and efficiency. All but the superficial muscle fibres are arranged along curved trajectories, and the myomeres form nested cones. Two conflicting performance goals shape the fibre trajectories of the axial muscles. Maximum power output requires that all fibres contract uniformly. In a bending fish, uniform contraction in a single myomere can be ensured by curved fibre trajectories. However, uniform strain is only desirable if all muscle fibres have the same contractile properties. The fish needs several muscle-fibre types that generate maximum power at different contraction speeds to ensure effective muscle power generation across a range of swimming speeds. Consequently, these different muscle-fibre types are better served by non-uniform contractions. High power output at a range of swimming speeds requires that muscle fibres with the same contractile properties contract uniformly. The ensuing helical fibre trajectories require cone-shaped myomeres to reduce wasteful internal deformation of the entire muscle when it contracts. It can be shown that the cone-shaped myomeres of fish can be explained by two design criteria: uniform contraction (uniform strain hypothesis) and minimal internal deformation (mechanical stability hypothesis). So far, only the latter hypothesis has found strong support. The contracting muscle causes the fish body to undulate. These body undulations interact with the surrounding water to generate thrust. The resulting flow behind the swimming fish forms vortex rings, whose arrangement reflects the fish's swimming performance. Anguilliform swimmers shed individual vortex rings during steady swimming. Carangiform swimmers shed a connected chain of vortex rings. The currently available sections through the total flow fields are often not an honest representation of the total momentum in the water , the wake of carangiform swimmers shows a net backward momentum without the fish accelerating , suggesting that our current picture of the generated flow is incomplete. To accelerate, undulatory swimmers decrease the angle of the vortex rings with the mean path of motion, which is consistent with an increased rate of backward momentum transfer. Carangiform swimmers also enlarge their vortex rings to accelerate and to swim at a higher speed, while eel, which are anguilliform swimmers, shed stronger vortex rings. [source]

    Magnetic investigation of heavy metals contamination in urban topsoils around the East Lake, Wuhan, China

    GEOPHYSICAL JOURNAL INTERNATIONAL, Issue 2 2007
    Tao Yang
    SUMMARY Magnetic measurements and heavy metal analyses were performed on 133 samples from the urban soils around the East Lake in Wuhan, China. Samples were collected from four areas with different environmental settings: a heavy industrial area well known for thermal power generation and steel works; villages located in the downwind area of the industrial area; a main road with heavy traffic and roads around the East Lake. Results show that concentrations of magnetic particle and heavy metals in urban topsoils are significantly elevated due to the input of coarser-grained magnetite from industrial (e.g. power generation and steel production) and other anthropogenic activities (e.g. vehicle emissions). Concentration-related magnetic parameters, for example, magnetic susceptibility, saturation isothermal remanent magnetization and anhysteretic remanent magnetization, significantly correlate with the concentration of heavy metals. Moreover, in terms of grain sizes, the magnetic particles of different origins can be efficiently discriminated at the studied region. Therefore, magnetic measurements provide a basis for discrimination and identification of different contamination sources, and can be used as an economic alternative to chemical analysis when mapping heavy metal contamination in urban soil around the East Lake region, Wuhan, China. [source]

    Fabrication and Electromechanical Characterization of a Piezoelectric Structural Fiber for Multifunctional Composites

    ADVANCED FUNCTIONAL MATERIALS, Issue 4 2009
    Yirong Lin
    Abstract The use of piezoceramic materials for structural sensing and actuation is a fairly well developed practice that has found use in a wide variety of applications. However, just as advanced composites offer numerous benefits over traditional engineering materials for structural design, actuators that utilize the active properties of piezoelectric fibers can improve upon many of the limitations encountered when using monolithic piezoceramic devices. Several new piezoelectric fiber composites have been developed; however, almost all studies have implemented these devices such that they are surface-bonded patches used for sensing or actuation. This paper will introduce a novel active piezoelectric structural fiber that can be laid up in a composite material to perform sensing and actuation, in addition to providing load bearing functionality. The sensing and actuation aspects of this multifunctional material will allow composites to be designed with numerous embedded functions, including structural health monitoring, power generation, vibration sensing and control, damping, and shape control through anisotropic actuation. This effort has developed a set of manufacturing techniques to fabricate the multifunctional fiber using a SiC fiber core and a BaTiO3 piezoelectric shell. The electromechanical coupling of the fiber is characterized using an atomic force microscope for various aspect ratios and is compared to predictions made using finite element modeling in ABAQUS. The results show good agreement between the finite element analysis model and indicate that the fibers could have coupling values as high as 68% of the active constituent used. [source]

    Isolation of Solid Solution Phases in Size-Controlled LixFePO4 at Room Temperature

    ADVANCED FUNCTIONAL MATERIALS, Issue 3 2009
    Genki Kobayashi
    Abstract State-of-the-art LiFePO4 technology has now opened the door for lithium ion batteries to take their place in large-scale applications such as plug-in hybrid vehicles. A high level of safety, significant cost reduction, and huge power generation are on the verge of being guaranteed for the most advanced energy storage system. The room-temperature phase diagram is essential to understand the facile electrode reaction of LixFePO4 (0,<,x,<,1), but it has not been fully understood. Here, intermediate solid solution phases close to x,=,0 and x,=,1 have been isolated at room temperature. Size-dependent modification of the phase diagram, as well as the systematic variation of lattice parameters inside the solid-solution compositional domain closely related to the electrochemical redox potential, are demonstrated. These experimental results reveal that the excess capacity that has been observed above and below the two-phase equilibrium potential is largely due to the bulk solid solution, and thus support the size-dependent miscibility gap model. [source]

    Theoretical analysis on thermoelectric power generation with rectangular-fin elements and its applicability in micro systems

    HEAT TRANSFER - ASIAN RESEARCH (FORMERLY HEAT TRANSFER-JAPANESE RESEARCH), Issue 3 2006
    Yutaka Oda
    Abstract A thermoelectric module, which consists of rectangular-fin elements and has a simple structure suitable for micro fabrication, was newly proposed for a micro- to milli-scale thermoelectric power generator. A unit model was introduced to examine the basic characteristics of thermoelectric power generation with rectangular-fin elements. Theoretical descriptions of the power density and conversion efficiency were given by solving one-dimensional heat and current flows inside the elements. Then, it was found that there exist optimum aspect ratios of the elements to achieve maximum power density and conversion efficiency. Power density becomes larger if the module is downsized with a similarity in shape, while conversion efficiency remains constant, i.e., smaller devices show better performance. Finally, comparative analysis with a standard pi-type module was conducted to emphasize the superiority of the proposed module in micro systems, when convective heat transfer resistance is taken into account. © 2006 Wiley Periodicals, Inc. Heat Trans Asian Res, 35(3): 224,244, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.20108 [source]

    Social risk assessment of large technical systems

    HUMAN FACTORS AND ERGONOMICS IN MANUFACTURING & SERVICE INDUSTRIES, Issue 4 2003
    H.J. Pasman
    A probabilistic approach to engineering advances. Since risk adhering to a technical structure can be determined quantitatively easier and more accurately than before, criteria for decision making are becoming more important. If the structure is in the public domain, and benefits are not felt, the voluntariness of being subjected to the risk becomes low. Decisions become, in such a case, a political issue on the basis of considerations of ethics, law, and social justice. For a specific case, the comparison of the economic benefits with the total costs, including risk reduction in a worst case scenario, play a major role as we have seen over and over again in, for example, planning nuclear power generation. A criterion for individual risk of 10,5 per year for the purpose of "external safety" is generally accepted. For social risk assessment, however, a group risk criterion is essential and much more difficult to define. An analysis is made. Examples of inconsistency are given. Further dialogue is encouraged. © 2003 Wiley Periodicals, Inc. Hum Factors Man 13: 305,316, 2003. [source]

    Regime-dependent streamflow sensitivities to Pacific climate modes cross the Georgia,Puget transboundary ecoregion

    HYDROLOGICAL PROCESSES, Issue 24 2007
    Sean W. Fleming
    Abstract The Georgia Basin,Puget Sound Lowland region of British Columbia (Canada) and Washington State (USA) presents a crucial test in environmental management due to its combination of abundant salmonid habitat, rapid population growth and urbanization, and multiple national jurisdictions. It is also hydrologically complex and heterogeneous, containing at least three streamflow regimes: pluvial (rainfall-driven winter freshet), nival (melt-driven summer freshet), and hybrid (both winter and summer freshets), reflecting differing elevation ranges within various watersheds. We performed bootstrapped composite analyses of river discharge, air temperature, and precipitation data to assess El Niño,Southern Oscillation (ENSO) and Pacific Decadal Oscillation (PDO) impacts upon annual hydrometeorological cycles across the study area. Canadian and American data were employed from a total of 21 hydrometric and four meteorological stations. The surface meteorological anomalies showed strong regional coherence. In contrast, the seasonal impacts of coherent modes of Pacific circulation variability were found to be fundamentally different between streamflow regimes. Thus, ENSO and PDO effects can vary from one stream to the next within this region, albeit in a systematic way. Furthermore, watershed glacial cover appeared to complicate such relationships locally; and an additional annual streamflow regime was identified that exhibits climatically driven non-linear phase transitions. The spatial heterogeneity of seasonal flow responses to climatic variability may have substantial implications to catchment-specific management and planning of water resources and hydroelectric power generation, and it may also have ecological consequences due to the matching or phase-locking of lotic and riparian biological activity and life cycles to the seasonal cycle. The results add to a growing body of literature suggesting that assessments of the streamflow impacts of ocean,atmosphere circulation modes must accommodate local hydrological characteristics and dynamics. Copyright © 2007 John Wiley & Sons, Ltd. The copyright in Paul H. Whitfield's contribution belongs to the Crown in right of Canada and such copyright material is reproduced with the permission of Environment Canada. [source]

    Optimal Control of Voltage in Distribution Systems by Voltage Reference Management

    IEEJ TRANSACTIONS ON ELECTRICAL AND ELECTRONIC ENGINEERING, Issue 5 2009
    Tomonobu Senjyu Student member
    Abstract Recently, renewable energy technologies such as wind turbine generators and photovoltaic (PV) systems have been introduced as distributed generations (DGs). Connections of a large amount of distributed generations may cause voltage deviation beyond the statutory range in distribution systems. A reactive power control of DGs can be a solution of this problem, and it also has a possibility to reduce distribution loss. In this paper, we propose a control methodology of voltage profile in a distribution system using reactive power control of inverters interfaced with DGs and tap changing transformers. In the proposed method, a one-day schedule of voltage references for the control devices are determined by an optimization technique based on predicted values of load demand and PV power generation. Reactive power control of interfaced inverters is implemented within the inverter capacity without reducing active power output. The proposed method accomplishes voltage regulation within the acceptable range and reduction of distribution loss. The effectiveness of the proposed method is confirmed by simulations. Copyright © 2009 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. [source]

    Fabrication and Application of an Oxide Thermoelectric System

    INTERNATIONAL JOURNAL OF APPLIED CERAMIC TECHNOLOGY, Issue 4 2007
    Ryoji Funahashi
    A plate-shaped thermoelectric module was prepared using 140 pairs of p -type Ca3Co4O9 (Co-349) and n -type LaNiO3 (Ni-113) bulks. The hot-pressed thermoelectric oxide bulks were connected with an Ag paste, incorporating oxide powder, and Ag sheets. The module's open-circuit voltage increases with increasing hot-side temperature (TH) and reaches 4.5 V at a TH of 1072 K in air. No deterioration in output power was seen when power generation was carried out 10 times at a TH of 723 K with intermediate cooling to room temperature. The module was successfully used to charge a lithium-ion battery in a mobile phone. Thermoelectric modules composed of p -type Co-349 and n -type CaMnO3 (Mn-113) bulks, which have a pipe shape, were constructed using Ag electrodes and stainless-steel tubes. The devices were connected with the stainless-steel tube coated with ZrO2 by thermal spray using a dielectric paste composed of silica glass and iron oxide. Power generation was carried out in flame by combustion of natural gas. Water flowed inside the stainless-steel tube for cooling. One module consisting of 54 pairs of legs can generate 1.5 V, 0.28 W, and steam simultaneously by installing in an instantaneous water heater. Power generation was carried out four times with intermediate cooling. Deterioration in the open-circuit voltage of the module was not observed after the fourth combustion. [source]

    A review on advances in alkali metal thermal to electric converters (AMTECs)

    INTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 10 2009
    Shuang-Ying Wu
    Abstract The alkali metal thermal to electric converter (AMTEC) is one of the most promising technologies for direct conversion of thermal energy to electricity and has been receiving attention in the field of energy conversion and utilization in the past several decades. This paper aims to present a comprehensive review of the state of the art in the research and development of the AMTEC, including its working principles and types, historical development and applications, analytical models, working fluids, electrode materials, as well as the performance and efficiency improvement. The current two major problems encountered by the AMTEC, the time-dependent power degradation and relatively low efficiency compared to its theoretical value, are discussed in depth. In addition, a brief comparison of the AMTEC with other direct thermal to electric converters (DTECs), such as the thermoelectrics converter (TEC), thermionics converter, and thermophotovoltaics converter, is given, and combinations of different DTECs to further improve DTECs' power generation and overall conversion efficiency are demonstrated. Future research and development directions and the issues that need to be further investigated are also suggested. It is believed that this comprehensive review will be beneficial to the design, simulation, analysis, performance assessment, and applications of various types of AMTECs. Copyright © 2009 John Wiley & Sons, Ltd. [source]

    Thermodynamic optimization of a solar system for cogeneration of water heating and absorption cooling

    INTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 13 2008
    R. Hovsapian
    Abstract This paper presents a contribution to understanding the behavior of solar-powered air conditioning and refrigeration systems with a view to determining the manner in which refrigeration rate, mass flows, heat transfer areas, and internal architecture are related. A cogeneration system consisting of a solar concentrator, a cavity-type receiver, a gas burner, and a thermal storage reservoir is devised to simultaneously produce heat (hot water) and cooling (absorption refrigerator system). A simplified mathematical model, which combines fundamental and empirical correlations, and principles of classical thermodynamics, mass and heat transfer, is developed. The proposed model is then utilized to simulate numerically the system transient and steady-state response under different operating and design conditions. A system global optimization for maximum performance (or minimum exergy destruction) in the search for minimum pull-down and pull-up times, and maximum system second law efficiency is performed with low computational time. Appropriate dimensionless groups are identified and the results are presented in normalized charts for general application. The numerical results show that the three-way maximized system second law efficiency, ,II,max,max,max, occurs when three system characteristic mass flow rates are optimally selected in general terms as dimensionless heat capacity rates, i.e. (,ss, ,wxwx, ,Hs)opt=(0.335, 0.28, 0.2). The minimum pull-down and pull-up times, and maximum second law efficiencies found with respect to the optimized operating parameters are sharp and, therefore, important to be considered in actual design. As a result, the model is expected to be a useful tool for simulation, design, and optimization of solar energy systems in the context of distributed power generation. Copyright © 2008 John Wiley & Sons, Ltd. [source]

    Status and development of PEM fuel cell technology

    INTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 5 2008
    F. Barbir
    Abstract Fuel cells are an emerging technology with applications in transportation, stationary and portable power generation, with outputs ranging from mW to MW. The most promising and most widely researched, developed and demonstrated type of fuel cells is proton exchange membrane (PEM) fuel cell. State of the art in PEM fuel cell technology and challenges in their development and widespread applications are discussed. Copyright © 2007 John Wiley & Sons, Ltd. [source]

    Comparison of evaporative inlet air cooling systems to enhance the gas turbine generated power

    INTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 15 2007
    Mohammad Ameri
    Abstract The gas turbine performance is highly sensitive to the compressor inlet temperature. The output of gas turbine falls to a value that is less than the rated output under high temperature conditions. In fact increase in inlet air temperature by 1°C will decrease the output power by 0.7% approximately. The solution of this problem is very important because the peak demand season also happens in the summer. One of the convenient methods of inlet air cooling is evaporating cooling which is appropriate for warm and dry weather. As most of the gas turbines in Iran are installed in such ambient conditions regions, therefore this method can be used to enhance the performance of the gas turbines. In this paper, an overview of technical and economic comparison of media system and fog system is given. The performance test results show that the mean output power of Frame-9 gas turbines is increased by 11 MW (14.5%) by the application of media cooling system in Fars power plant and 8.1 MW (8.9%) and 9.5 MW (11%) by the application of fog cooling system in Ghom and Shahid Rajaie power plants, respectively. The total enhanced power generation in the summer of 2004 was 2970, 1701 and 1340 MWh for the Fars, Ghom and Shahid Rajaie power plants, respectively. The economical studies show that the payback periods are estimated to be around 2 and 3 years for fog and media systems, respectively. This study has shown that both methods are suitable for the dry and hot areas for gas turbine power augmentation. Copyright © 2007 John Wiley & Sons, Ltd. [source]

    Dynamic characteristics of a PEM fuel cell system for individual houses

    INTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 15 2006
    S. ObaraArticle first published online: 1 AUG 200
    Abstract The method of determination of the control variables for a system controller, which controls the electric power output of a solid-polymer-membrane (PEM) fuel cell system during electric power load fluctuations, was considered. The operation was clarified for the response characteristics of electric power generation for setting the control variables of proportional action and integral action considered to be the optimal for the system controller. The power load pattern of an individual house consists of loads usually moved up and down rapidly for a short time. Until now, there have been no examples showing the characteristics of the power generation efficiency of a system that follows a load pattern that moves up and down rapidly. Therefore, this paper investigates the relation of the control variables and power generation efficiency when adding change that simulates the load of a house to PEM fuel cell cogeneration. As a result, it was shown that an operation, minimally influenced by load fluctuations, can be performed by changing the control variables using the value of the electric power load of a system. Copyright © 2006 John Wiley & Sons, Ltd. [source]