Distribution by Scientific Domains
Distribution within Engineering

Kinds of Generator

  • central pattern generator
  • induction generator
  • pattern generator
  • photoacid generator
  • pulse generator
  • radical generator
  • residual generator
  • rotating-anode generator
  • signal generator
  • synchronous generator
  • x-ray generator

  • Terms modified by Generator

  • generator change
  • generator failure
  • generator replacement

  • Selected Abstracts

    A Hidden-picture Puzzles Generator

    Jong-Chul Yoon
    Abstract A hidden-picture puzzle contains objects hidden in a background image, in such a way that each object fits closely into a local region of the background. Our system converts image of the background and objects into line drawing, and then finds places in which to hide transformed versions of the objects using rotation-invariant shape context matching. During the hiding process, each object is subjected to a slight deformation to enhance its similarity to the background. The results were assessed by a panel of puzzle-solvers. [source]

    Coupling integrated Earth System Model components with BFG2

    C. W. Armstrong
    Abstract GENIE is a suite of modular Earth System Model components coupled in a variety of configurations used to investigate climate phenomena. As part of the GENIEfy project, there is a desire to make the activity of coupling GENIE configurations more flexible in order to ease the integration of new components, permit experimentation with alternative model orderings and connectivity, and execute GENIE components in distributed environments. The current coupling framework is inflexible because models are run in a fixed order by a prescriptive main code. This paper shows how the BFG2 (Bespoke Framework Generator,version 2) coupling tool offers significantly more flexibility. Using BFG2, scientists describe GENIE configurations as metadata that can then be transformed automatically into the desired framework. It is demonstrated that BFG2 provides flexibility in composition and deployment, improvements that are brought without modification to the GENIE components, without loss of performance and in a such a manner that it is possible to produce exactly the same results as under the original framework. We also demonstrate how BFG2 may be used to improve the performance of future GENIE coupled models. Copyright © 2008 John Wiley & Sons, Ltd. [source]

    Sodium Borohydride Hydrolysis as Hydrogen Generator: Issues, State of the Art and Applicability Upstream from a Fuel Cell

    FUEL CELLS, Issue 3 2010
    U. B. Demirci
    Abstract Today there is a consensus regarding the potential of NaBH4 as a good candidate for hydrogen storage and release via hydrolysis reaction, especially for mobile, portable and niche applications. However as gone through in the present paper two main issues, which are the most investigated throughout the open literature, still avoid NaBH4 to be competitive. The first one is water handling. The second one is the catalytic material used to accelerate the hydrolysis reaction. Both issues are objects of great attentions as it can be noticed throughout the open literature. This review presents and discusses the various strategies which were considered until now by many studies to manage water and to improve catalysts performances (reactivity and durability). Published studies show real improvements and much more efforts might lead to significant overhangs. Nevertheless, the results show that we are still far from envisaging short-term commercialisation. [source]

    TSGen: a tool for modeling of frame loss in streaming video

    John Shahbazian
    Packet loss affects the quality of streaming video. We describe a new Time Series Generator (TSGen) tool to generate a time series that models video packet loss phenomena by capturing both the moment and autocorrelation signatures of frame loss in a video stream.,Copyright © 2004 John Wiley & Sons, Ltd. [source]

    Increased Defibrillator Charge Time Following Direct Trauma to an ICD Generator: Blunt Consequences

    First page of article [source]

    Feasibility and Initial Results of an Internet-Based Pacemaker and ICD Pulse Generator and Lead Registry

    HAUSER, R., et al.: Feasibility and Initial Results of an Internet-Based Pacemaker and ICD Pulse Generator and Lead Registry. The medical community has no independent source of timely information regarding the performance of pacemaker and ICD pulse generators and leads. Accordingly, the authors established an Internet-based registry of pacemaker and ICD pulse generator and lead failures ( During the first year, they found three previously unreported device problems that were promptly communicated to the participants. Of the failures reported, 11% of ICD and 10% of pacemaker pulse generator failures were heralded by signs other than the expected elective replacement indicator (ERI). Average ICD battery longevity was 4.0 ± 0.7 years, and average dual chamber pacemaker battery longevity was 6.8 ± 2.6 years. Disrupted insulation accounted for 54% of pacemaker and 29% of ICD lead failures. Compared to pacemaker pulse generator and lead failure, ICD device failures were more likely to cause severe clinical consequences. In conclusion, an Internet-based registry is feasible and capable of providing timely data regarding the signs, causes, and clinical consequences of pacemaker and ICD failures. [source]

    Fast near-infra-red spectroscopic Mueller matrix ellipsometer based on ferroelectric liquid crystal retarders

    J. Ladstein
    Abstract This paper reports on the design and construction of the first near-infra-red spectroscopic Mueller Matrix Ellipsometer (MME) based on Ferroelectric Liquid Crystal retarders (FLC) and fixed waveplates. The design was performed by assuming ideal optical polarizing components. In particular, the current FLC-MME is optimised to operate in the near-infra-red (NIR) spectral range from 800 nm to 1800 nm. The FLC based Polarization State Generator (PSG) and Polarization State Analyzer (PSA) have been optimized by keeping the condition number of the PSG's modulation matrix and the PSA's analysis matrix close to an optimum over the spectral design range. The design is realized in a setup using the full Mueller matrix measurement formalism based on the Eigenvalue Calibration Method (ECM). The actual modulation matrix and analysis matrix are obtained from the ECM, and the condition numbers immediately indicates the quality of the design. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

    Bioreactor Coupled with Electromagnetic Field Generator: Effects of Extremely Low Frequency Electromagnetic Fields on Ethanol Production by Saccharomycescerevisiae

    Victor H. Perez
    The effect of extremely low frequency (ELF) magnetic fields on ethanol production by Saccharomyces cerevisiae using sugar cane molasses was studied during batch fermentation. The cellular suspension from the fermentor was externally recycled through a stainless steel tube inserted in two magnetic field generators, and consequently, the ethanol production was intensified. Two magnetic field generators were coupled to the bioreactor, which were operated conveniently in simple or combined ways. Therefore, the recycle velocity and intensity of the magnetic field varied in a range of 0.6,1.4 m s,1 and 5,20 mT, respectively. However, under the best conditions with the magnetic field treatment (0.9,1.2 m s,1 and 20 mT plus solenoid), the overall volumetric ethanol productivity was approximately 17% higher than in the control experiment. These results made it possible to verify the effectiveness of the dynamic magnetic treatment since the fermentations with magnetic treatment reached their final stage in less time, i.e., approximately 2 h earlier, when compared with the control experiment. [source]

    Toolkits for automatic web service and GUI generation: KWATT

    Yenan Qu
    In a previous paper, we explained how to translate an input script into a functional web service, independent of the script language. We extend this work by considering the automatic creation of graphical user interfaces to allow interaction between a user and the web service generated by KWATT. The key aspects of this work are three-fold. First, comment lines inserted into the script provide hints to the interface generator regarding the interface widgets. Second, the structure of the GUI is encoded into an XML file, and third, a plugin architecture permits the interface to be the output in one of several languages. We present an example interface to illustrate the concepts. Copyright © 2009 John Wiley & Sons, Ltd. [source]

    Getting more from your multicore: exploiting OpenMP from an open-source numerical scripting language

    Michael S. Noble
    Abstract We introduce SLIRP, a module generator for the S-Lang numerical scripting language, with a focus on its vectorization capabilities. We demonstrate how both SLIRP and S-Lang were easily adapted to exploit the inherent parallelism of high-level mathematical languages with OpenMP, allowing general users to employ tightly coupled multiprocessors in scriptable research calculations while requiring no special knowledge of parallel programming. Motivated by examples in the ISIS astrophysical modeling and analysis tool, performance figures are presented for several machine and compiler configurations, demonstrating beneficial speedups for real-world operations. Copyright © 2008 John Wiley & Sons, Ltd. [source]

    68Ga-PET: a powerful generator-based alternative to cyclotron-based PET radiopharmaceuticals

    Melpomeni Fani
    Abstract PET (positron emission tomography) is a powerful diagnostic and imaging technique which requires short-lived positron emitting isotopes. The most commonly used are accelerator-produced 11C and 18F. An alternative is the use of metallic positron emitters. Among them 68Ga deserves special attention because of its availability from long-lived 68Ge/68Ga generator systems which render 68Ga radiopharmacy independent of an onsite cyclotron. The coordination chemistry of Ga3+ is dominated by its hard acid character. A variety of mono- and bifunctional chelators have been developed which allow the formation of stable 68Ga3+complexes and convenient coupling to biomolecules. 68Ga coupling to small biomolecules is potentially an alternative to 18F- and 11C-based radiopharmacy. In particular, peptides targeting G-protein coupled receptors overexpressed on human tumour cells have shown preclinically and clinically high and specific tumour uptake. Kit-formulated precursors along with the generator may be provided, similar to the 99Mo/99mTc-based radiopharmacy, still the mainstay of nuclear medicine. Copyright © 2008 John Wiley & Sons, Ltd. [source]

    Vibration signals from the FT joint can induce phase transitions in both directions in motoneuron pools of the stick insect walking system

    Ulrich Bässler
    Abstract The influence of vibratory signals from the femoral chordotonal organ fCO on the activities of muscles and motoneurons in the three main leg joints of the stick insect leg, i.e., the thoraco,coxal (TC) joint, the coxa,trochanteral (CT) joint, and the femur,tibia (FT) joint, was investigated when the animal was in the active behavioral state. Vibration stimuli induced a switch in motor activity (phase transition), for example, in the FT joint motor activity switched from flexor tibiae to extensor tibiae or vice versa. Similarly, fCO vibration induced phase transitions in both directions between the motoneuron pools of the TC joint and the CT joint. There was no correlation between the directions of phase transition in different joints. Vibration stimuli presented during simultaneous fCO elongation terminated the reflex reversal motor pattern in the FT joint prematurely by activating extensor and inactivating flexor tibiae motoneurons. In legs with freely moving tibia, fCO vibration promoted phase transitions in tibial movement. Furthermore, ground vibration promoted stance,swing transitions as long as the leg was not close to its anterior extreme position during stepping. Our results provide evidence that, in the active behavioral state of the stick insect, vibration signals can access the rhythm generating or bistable networks of the three main leg joints and can promote phase transitions in motor activity in both directions. The results substantiate earlier findings on the modular structure of the single-leg walking pattern generator and indicate a new mechanism of how sensory influence can contribute to the synchronization of phase transitions in adjacent leg joints independent of the walking direction. © 2003 Wiley Periodicals, Inc. J Neurobiol 56: 125,138, 2003 [source]

    Blockade of the central generator of locomotor rhythm by noncompetitive NMDA receptor antagonists in Drosophila larvae

    Daniel Cattaert
    Abstract The noncompetitive antagonists of the vertebrate N -methyl- D -aspartate (NMDA) receptor dizocilpine (MK 801) and phencyclidine (PCP), delivered in food, were found to induce a marked and reversible inhibition of locomotor activity in Drosophilamelanogaster larvae. To determine the site of action of these antagonists, we used an in vitro preparation of the Drosophila third-instar larva, preserving the central nervous system and segmental nerves with their connections to muscle fibers of the body wall. Intracellular recordings were made from ventral muscle fibers 6 and 7 in the abdominal segments. In most larvae, long-lasting (>1 h) spontaneous rhythmic motor activities were recorded in the absence of pharmacological activation. After sectioning of the connections between the brain and abdominal ganglia, the rhythm disappeared, but it could be partially restored by perfusing the muscarinic agonist oxotremorine, indicating that the activity was generated in the ventral nerve cord. MK 801 and PCP rapidly and efficiently inhibited the locomotor rhythm in a dose-dependent manner, the rhythm being totally blocked in 2 min with doses over 0.1 mg/mL. In contrast, more hydrophilic competitive NMDA antagonists had no effect on the motor rhythm in this preparation. MK 801 did not affect neuromuscular glutamatergic transmission at similar doses, as demonstrated by monitoring the responses elicited by electrical stimulation of the motor nerve or pressure applied glutamate. The presence of oxotremorine did not prevent the blocking effect of MK 801. These results show that MK 801 and PCP specifically inhibit centrally generated rhythmic activity in Drosophila, and suggest a possible role for NMDA-like receptors in locomotor rhythm control in the insect CNS. © 2001 John Wiley & Sons, Inc. J Neurobiol 48: 58,73, 2001 [source]

    Laboratory tests of steel simple torsionally unbalanced models

    Jaime De-la-Colina
    Abstract The objective of this work is to obtain estimations of the amplification factors , and , used for torsion design of buildings, from experiments. For this study, simple one-storey torsionally unbalanced (TU) steel models were considered. Models consisted of a deck supported on four columns with a selected arrangement of hinges at column ends. Two theoretical structural eccentricities (e = 0.05 and 0.15) were considered. Models were excited with a simple long-period pendulum consisting of a hanging platform with a forced-vibration generator on it. Eight models were tested at several excitation levels (frequencies and force magnitudes) in both ranges of behaviour: elastic and inelastic. Experiments were conducted at three frequency ratios of excitation. Registered accelerations of the pendulum platform indicate that the experimental set-up leads to excitations that resemble narrow-band seismic ground motions. Frame shear force estimations, based on accelerations recorded at both deck sides, indicate that torsion design factors (, and ,) depend on eccentricity. Estimations of frame shears based on measurements indicate that for normalized eccentricities e , 0.025, the amplification , can be between 2 and 3; while , factor resulted between 0.0 and 1.6. Copyright © 2006 John Wiley & Sons, Ltd. [source]

    Basic study of pole change generator for micro windmill generation system

    Kazuto Yukita
    Abstract This paper proposes a pole change generator for a windmill. Since micro windmill systems generate power from natural energy, power generation characteristics across a wide band are necessary. However, the conventional generator, in which the open voltage is simply proportional to the rotational velocity, encounters difficulty in generating power across a wide range of rotational velocities from low to high, because of the power generation characteristics. To develop a generator with a wide power band suitable for a micro windmill, this paper proposes a technique for switching the status of the generator coil connection. To demonstrate the effectiveness of pole changing, we use a pole-changing generator with 16 coils as an example. The coils can be connected using four patterns: 16-pole series, 8-pole 2-parallel, 4-pole 4-parallel, and 2-pole 8-parallel. Theoretical and experimental studies from this point of view demonstrate that this technique is effective. © 2010 Wiley Periodicals, Inc. Electr Eng Jpn, 171(1): 28,36, 2010; Published online in Wiley InterScience ( DOI 10.1002/eej.20873 [source]

    A perturbation analysis of harmonic generation from saturated elements in power systems

    Teruhisa Kumano
    Abstract Nonlinear phenomena such as saturation of magnetic flux have considerable effects in power systems analysis. It is reported that a failure in a real 500-kV system triggered islanding operation, where resultant even harmonics caused malfunctions in protective relays. It is also reported that the major origin of this wave distortion is nothing but unidirectional magnetization of the transformer iron core. Time simulation is widely used today to analyze phenomena of this type, but it has basically two shortcomings. One is that the time simulation takes too much computing time in the vicinity of inflection points in the saturation characteristic curve because certain iterative procedures such as N-R (Newton,Raphson) must be used and such methods tend to be caught in an ill-conditioned numerical hunting. The other is that such simulation methods sometimes do not aid an intuitive understanding of the studied phenomenon because all of the nonlinear equations are treated in matrix form and are not properly divided into understandable parts, as is done in linear systems. This paper proposes a new computation scheme that is based on the so-called perturbation method. Magnetic saturation of iron cores in a generator and a transformer are taken into account. The proposed method has a special feature to deal with the first shortcoming of the N-R-based time simulation method stated above. The proposed method does not use an iterative process to reduce the equation residue, but uses perturbation series, so that it is free of the ill-conditioning problem. The user need only calculate the perturbation terms one by one until the necessary accuracy is attained. In a numerical example treated in the present paper, first-order perturbation can achieve reasonably high accuracy, which means very fast computing time. In a numerical study, three nonlinear elements are considered. The calculation results are almost identical to the conventional N-R-based time simulation, which shows the validity of the method. The proposed method can be effectively used in screening where many case studies are needed. © 2009 Wiley Periodicals, Inc. Electr Eng Jpn, 170(4): 35,42, 2010; Published online in Wiley InterScience ( DOI 10.1002/eej.20895 [source]

    Computation of locational and hourly maximum output of a distributed generator connected to a distribution feeder

    Yasuhiro Hayashi
    Abstract Recently, the total number of distributed generation such as photovoltaic generation systems and wind turbine generation systems connected to a distribution network has drastically increased. Distributed generation using renewable energy can reduce the distribution loss and emission of CO2. However, the distribution network with the distributed generators must be operated while maintaining the reliability of the power supply and power quality. In this paper, the authors propose a computational method to determine the maximum output of a distributed generator under operational constraints [(1) voltage limit, (2) line current capacity, and (3) no reverse flow to bank] at arbitrary connection points and hourly periods. In the proposed method, a three-phase iterative load flow calculation is applied to evaluate the above operational constraints. The three-phase iterative load flow calculation has two simple procedures: (Procedure 1) addition of load currents from the terminal node of the feeder to root one, and (Procedure 2) subtraction of voltage drop from the root node of the feeder to terminal one. In order to check the validity of the proposed method, numerical simulations are performed for a distribution system model. Furthermore, the characteristics of locational and hourly maximum output of a distributed generator connected to a distribution feeder are analyzed using several numerical examples. © 2009 Wiley Periodicals, Inc. Electr Eng Jpn, 167(2): 38,47, 2009; Published online in Wiley InterScience ( DOI 10.1002/eej.20610 [source]

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

    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 ( DOI 10.1002/eej.20695 [source]

    Effects of output power fluctuation on short-circuit current of induction-type wind power generators

    Teruhisa Kumano
    Abstract Effects of the fluctuation inherent in wind speed are studied by a probabilistic method. The random variation in wind speed is responsible for random behavior in output power and internal voltage of a wind power generator. In case of fault occurrence at the instant of high internal voltage, the resultant short-circuit current will be big, and vice versa. The DC component is also affected. According to the study, 2.4% and 1.3% increase of short-circuit current in AC and DC components are observed respectively in a large variation case. This implies that the wind speed variation should be considered for accurate short-circuit study. © 2008 Wiley Periodicals, Inc. Electr Eng Jpn, 166(3): 27,36, 2009; Published online in Wiley InterScience ( DOI 10.1002/eej.20721 [source]

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

    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 ( DOI 10.1002/eej.20399 [source]

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

    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 ( DOI 10.1002/eej.20394 [source]

    State criterion of wind turbine generator operation using tower shadow effect (Part 2)

    Tadashi Naitoh
    Abstract In order to obtain wind energy effectively, the pole-change-type induction generators are used as the wind turbine generators. Otherwise, the pole-change-type induction generator causes the voltage dips at pole changing time. To maintain the power quality, it is important to know the state change of the generator operation. Therefore, the authors have studied a state criterion of generator using the tower shadow effect, which is the active power oscillation caused by a rotation torque drop when the tower and the turbine blade overlap each other. In this paper, an improved identification method of oscillation frequency, which is the criterion of wind turbine generator operation, is proposed. The proposed method is applied to measured data and good results are obtained. © 2007 Wiley Periodicals, Inc. Electr Eng Jpn, 162(1): 25,31, 2008; Published online in Wiley InterScience ( DOI 10.1002/eej.20395 [source]

    Construction of Lyapunov function for power system based on solving linear matrix inequality

    Atsushi Ishigame
    Abstract This paper presents construction of Lyapunov functions for power systems based on solving the Linear Matrix Inequality (LMI) derived from the Lyapunov stability theorem considering the dynamics of load characteristic and AVR control system. The proposed Lyapunov function is constructed as a quadratic form of state variables and an integral term which satisfies the curl equation and the sector condition. An induction machine and a synchronous machine are considered as load characteristics. One-machine one-load infinite bus system is considered taking into account the flux decay effects and AVR with one time constant of the generator. To verify the proposed Lyapunov function, the transient stability assessment is shown. The critical clearing times given by the proposed Lyapunov function are compared with those obtained by the numerical integration method, and they are shown to be practical. © 2007 Wiley Periodicals, Inc. Electr Eng Jpn, 158(4): 42, 50, 2007; Published online in Wiley InterScience (www.interscience. DOI 10.1002/eej.20328 [source]

    SECM Visualization of Spatial Variability of Enzyme-Polymer Spots.

    ELECTROANALYSIS, Issue 19-20 2006
    2: Complex Interference Elimination by Means of Selection of Highest Sensitivity Sensor Substructures, Artificial Neural Networks
    Abstract Polymer spots with entrapped glucose oxidase were fabricated on glass surfaces and the localized enzymatic response was subsequently visualized using scanning electrochemical microscopy (SECM) in the generator,collector mode. SECM images were obtained under simultaneous variation of the concentration of glucose (0,6,mM) and ascorbic acid (0,200,,M), or, in a second set of experiments, of glucose (0,2,mM) and 2-deoxy- D(+)-glucose (0,4,mM). Aiming at the quantification of the mixture components discretization of the response surfaces of the overall enzyme/polymer spot into numerous spatially defined microsensor substructures was performed. Sensitivity of sensor substructures to measured analytes was calculated and patterns of variability in the data were analyzed before and after elimination of interferences using principal component analysis. Using artificial neural networks which were fed with the data provided by the sensor substructures showing highest sensitivity for glucose, glucose concentration could be calculated in solutions containing unknown amounts of ascorbic acid with a good accuracy (RMSE 0.17,mM). Using, as an input data set, measurements provided by sensing substructures showing highest sensitivity for ascorbic acid in combination with the response of the sensors showing highest dependence on the glucose concentration, the error of the ascorbic acid concentration calculation in solution containing the unknown amount of glucose was 10,,M. Similarly, prediction of the glucose concentration in the presence of 2-deoxy- D(+)-glucose was possible with a RMSE of 0.1,mM while the error of the calculation of 2-deoxy- D(+)-glucose concentrations in the presence of unknown concentrations of glucose was 0.36,mM. [source]

    Ultrasonic treatment of waste activated sludge

    Raf Dewil
    Abstract Activated sludge processes are key technologies to treat wastewater. These biological processes produce huge amounts of waste activated sludge (WAS), now commonly called biosolids. Mechanical, thermal, and/or chemical WAS conditioning techniques have been proposed to reduce the sludge burden. The ultrasonic treatment of WAS is quite novel. The present paper reports on extensive investigations using an ultrasonic treatment of WAS, to study its potential to meet one or all of four objectives: (1) reduce WAS quantities; (2) achieve a better dewaterability; (3) provoke a release of soluble chemical oxygen demand (COD) from the biosolids, preferably transformed into biodegradable organics; and (4) possibly destroy the filamentous microorganisms responsible for sludge bulking. Although meeting these objectives would help to solve the problems cited, the energy consumption could be a considerable drawback: the paper will thus assess whether all or some objectives are met, and at what operational cost. A literature survey defines the occurring phenomena (cavitation) and the important operation parameters [such as frequency, duration, specific energy input (SE)]. The experiments are carried out in a batch reactor of volume up to 2.3 L. The ultrasonic equipment consisted of a generator, a converter, and a sonotrode, supplied by Alpha Ultrasonics under the brand name of Telsonic. Three different kinds of sludge were tested, with different concentrations of dry solids (DS) between approximately 3.5 and 14 g DS/L WAS. Ultrasonic energy was introduced in a continuous manner (against possible pulsed operation). The major operational parameters studied include duration of the ultrasonic treatment and specific energy input. The applied frequency was set at 20 kHz. The release of COD from the WAS phase into the filtrate phase is a function of the specific energy input with yields of nearly 30% achievable at SE values of 30,000 kJ/kg DS. A major fraction of the COD is transformed into biodegradable organics (BOD). The reduction in DS fraction of the sludge is proportional to the COD release rates. Although the DS content is reduced, the dewaterability of the sludge is not improved. This reflects itself in increased filtration times during vacuum filtration and in increased values of the capillary suction time (CST). This more difficult dewaterability is the result of considerably reduced floc sizes, offering an extended surface area: more surface water is bound (CST increases) and the filterability decreases as a result of clogging of the cake. To reach the same dryness as for the untreated cake, the required dosage of polyelectrolyte is nearly doubled when the SE of the ultrasound treatment is increased from 7500 to 20,000 kJ/kg DS. The ultrasonic reduction of filamentous WAS organisms is not conclusive and very little effect is seen at low intensities and short treatment durations. Microscopic analysis of the WAS identified the dominant presence of Actynomyces. The release of soluble COD and BOD certainly merit further research. © 2006 American Institute of Chemical Engineers Environ Prog, 2006 [source]

    In-Situ ozonation of contaminated groundwater

    Michael A. Nimmer
    This paper presents case studies in the application of insitu ozone sparging to remediate petroleum contaminated groundwater. This technology was developed and installed due to shortcomings with other conventional remedial technologies evaluated for groundwater remediation. The main objective of this study was to develop a system to supply ozone to the groundwater aquifer and to evaluate the system performance in the field. Three different applications were evaluated for this study, all containing petroleum-contaminated groundwater. The ozone sparging system consists of an air compressor, ozone generator, a programmable logic controller, and associated gauges and controls. The mixture of air and ozone is injected into the groundwater aquifer through microporous sparge points contained in various sparge well designs. The initial results from the three applications demonstrated that ozone sparging is a viable alternative to remediate petroleum -contaminated groundwater. Significant reductions in petroleum constituents we re observed shortly after system start-up at all sites. During the one to two years operation at the three sites, a number of maintenance items we re identified; these items we re addressed by modifications to the system design and operation. A long-term evaluation of the system operation has not yet been performed. [source]

    Meshing noise effect in design of experiments using computer experiments

    ENVIRONMETRICS, Issue 5-6 2002
    J. P. Caire
    Abstract This work is intended to show the influence of grid length and meshing technique on the empirical modeling of current distribution in an industrial electroplating reactor. This study confirms the interest of usual DOEs for computer experiments. Any 2D mesh generator induced, in this sensitive case, a significant noise representing only less than 5 per cent of the response. The ,experimental error' obeys a normal distribution and the associated replicate SDs represents 20 per cent of the global residual standard deviation. The geometry seems also to influence the corresponding noise. If the current density uniformity could be considered as a severe test, it is obvious that the noise generated by meshing would be amplified for 3D grids that will be in common use in future years. Copyright © 2002 John Wiley & Sons, Ltd. [source]

    Vagus Nerve Stimulation Therapy Induces Changes in Heart Rate of Children during Sleep

    EPILEPSIA, Issue 5 2007
    Boubker Zaaimi
    Summary:,Purpose: This study analyzed changes in the heart rates of children receiving vagus nerve stimulation (VNS) therapy for pharmacoresistant epilepsy. Methods: Changes in the heart rates of ten children receiving VNS therapy for pharmacoresistant epilepsy were evaluated with polysomnographic recordings, including electrocardiogram (ECG), EEG, thoraco-abdominal distension, nasal airflow, and VNS artifacts. Measurements during stimulation were compared with those at baseline for each patient. Result: While the VNS therapy pulse generator was delivering stimulation, the heart rates of four children increased significantly (p < 0.01), decreased for one child, and increased at the end of the stimulation for one child. The heart rates of four children did not change. Changes in heart rate varied during VNS, within stimulation cycles for individual children and from one child to another. Changes in heart rate differed between rapid eye movement (REM) and non-REM (NREM) sleep states. Respiratory changes (increases in frequency and decreases in amplitude) were concomitant with the changes in heart rate. Conclusion: In this case series of children with pharmacoresistant epilepsy, cardiorespiratory variations occurred while the VNS therapy pulse generator was delivering stimulation. Understanding these variations may allow further optimization of VNS parameters. [source]

    Effect of magnitude and direction of force on laryngeal abduction: Implications for the nerve-muscle pedicle graft technique

    P. CRAMP
    Summary Reasons for performing study: The nerve-muscle pedicle graft technique is a treatment for recurrent laryngeal neuropathy (RLN), but the optimal placement of the pedicles within the cricoarytenoideus dorsalis (CAD) muscle is unknown. Hypothesis: The magnitude and direction of force placed on the muscular process of the left arytenoid cartilage affects the magnitude of laryngeal abduction. Methods: Five larynges were harvested from cadavers. Using increments of 0.98 N, a dead-weight force generator applied a force of 0,14.7 N for 1 min each to the left muscular process at 0, 10, 20, 30, 40, 50, 60 and 70° angles. The rima glottis was photographed digitally 1 min after each force had been applied. Distances between biomarkers (Lines 1,4) and right to left angle quotient (RLQ) were used to assess the degree of left arytenoid abduction. Results: Increasing force from 0,14.7 N progressively and significantly increased the length of all lines and RLQ, indicating abduction. Furthermore, there was a significant interaction between force and angles. Applying forces of 7.84 N or greater (Lines 2,4 and RLQ) or 11.76 N or greater (Line 1) at angles 0, 10, 20 and 30° resulted in significantly greater abduction than applying the same forces at 40, 50, 60 and 70°. Angles of 0,30° correspond with the direction of pull exerted by the lateral compartment of the CAD muscle. Conclusion: In RLN, nerve-muscle pedicle grafts should be placed preferentially in the lateral rather than in the medial compartment of the CAD muscle. Potential relevance: The information presented can be used to assist surgeons in the planning and application of the nerve-muscle pedicle graft procedure. [source]

    Phenotype of V2-derived interneurons and their relationship to the axon guidance molecule EphA4 in the developing mouse spinal cord

    Line Lundfald
    Abstract The ventral spinal cord consists of interneuron groups arising from distinct, genetically defined, progenitor domains along the dorsoventral axis. Many of these interneuron groups settle in the ventral spinal cord which, in mammals, contains the central pattern generator for locomotion. In order to better understand the locomotor networks, we have used different transgenic mice for anatomical characterization of one of these interneuron groups, called V2 interneurons. Neurons in this group are either V2a interneurons marked by the postmitotic expression of the transcription factor Chx10, or V2b interneurons which express the transcription factors Gata2 and Gata3. We found that all V2a and most V2b interneurons were ipsilaterally projecting in embryos as well as in newborns. V2a interneurons were for the most part glutamatergic while V2b interneurons were mainly GABAergic or glycinergic. Furthermore, we demonstrated that a large proportion of V2 interneurons expressed the axon guidance molecule EphA4, a molecule previously shown to be important for correct organization of locomotor networks. We also showed that V2 interneurons and motor neurons alone did not account for all EphA4-expressing neurons in the spinal cord. Together, these findings enable a better interpretation of neural networks underlying locomotion, and open up the search for as yet unknown components of the mammalian central pattern generator. [source]