Energy Technology Data Exchange (ETDEWEB)

The high frequency, low mode number toroidicity-induced Alfven eigenmodes (TAE) are shown to be driven unstable by the circulating and/or trapped {alpha}-particles through the wave-particle resonances. Satisfying the resonance condition requires that the {alpha}-particle birth speed v{sub {alpha}} {ge} v{sub A}/2{vert bar}m-nq{vert bar}, where v{sub A} is the Alfven speed, m is the poloidal model number, and n is the toroidal mode number. To destabilize the TAE modes, the inverse Landau damping associated with the {alpha}-particle pressure gradient free energy must overcome the velocity space Landau damping due to both the {alpha}-particles and the core electrons and ions. The growth rate was studied analytically with a perturbative formula derived from the quadratic dispersion relation, and numerically with the aid of the NOVA-K code. Stability criteria in terms of the ...

Energy Technology Data Exchange (ETDEWEB)

Operating the Stanford Linear Collider (SLC) at 120Hz repetition rate requires the presence of two bunches in both the electron and the positron damping ring. The {pi}-mode instability, a coupled bunch instability where the two bunches oscillate with a phase difference of 180{degrees}, had been observed in both rings with low current thresholds of 7{sup *}10{sup 9} particles per bunch. To avoid the instability, the RF system had to be operated in ways which in general reduced the cavity gap voltages and required constant operational attention. For the 1992 running cycle a passive cavity was installed and successfully tested. It is tuned to the frequency of the lower synchrotron oscillation sideband of an odd revolution harmonic. The impedance of the cavity then damps {pi}-mode oscillations very similar to the Robinson damping provided by the main RF cavities which damps O-mode ...

CERN Document Server

The problem of spectra formation in hydrodynamic approach to A+A collisions is discussed. It is analyzed in terms of the two different objects: distribution and emission functions. We show that though the process of particle liberation, described by the emission function, is, usually, continuous in time, the observable spectra can be also expressed by means of the Landau/Cooper-Frye prescription. We argue that such an approximate duality results from some symmetry properties that systems in A+A collisions reach to the end of hydrodynamic evolution and reduction of the collision rate at post hydrodynamic stage

CERN Document Server

We present a new computation of the linear tidal interaction of a protoplanetary core with a thin gaseous disc in which it is fully embedded. For the first time a discussion of the orbital evolution of cores with eccentricity (e) significantly larger than the gas-disc scale height to radius ratio (H/r) is given. We find that the direction of orbital migration reverses for e>1.1H/r. This occurs as a result of the orbital crossing of resonances in the disc that do not overlap the orbit when the eccentricity is very small. Simple expressions giving approximate fits to the eccentricity damping rate and the orbital migration rate are presented. We go on to calculate the rate of increase of the mean eccentricity for a system of protoplanetary cores due to dynamical relaxation. By equating the eccentricity damping time-scale with the dynamical relaxation time-scale we deduce that an ...

Energy Technology Data Exchange (ETDEWEB)

A new multigrid algorithm based on the method of self-correction for the solution of elliptic problems is described. The method exploits information contained in the residual to dynamically modify the source term (right-hand side) of the elliptic problem. It is shown that the self-correcting solver is more efficient at damping the short wavelength modes of the algebraic error than its standard equivalent. When used in conjunction with a multigrid method, the resulting solver displays an improved convergence rate with no additional computational work.

International Nuclear Information System (INIS)

A general theoretical approach for the study of the two-dimensional structure of high-n Toroidal Alfven Eigenmodes (TAE) in finite-#beta#, large aspect ratio (R_o/a much-gt 1) tokamak equilibria is presented. Here, n is the toroidal mode number, #beta# = plasma/magnetic pressure, and a(R_o) is the minor (major) radius of the torus. It is shown how the general pseudo-differential boundary value problem for the radial eigenmode structure can be systematically constructed from the local dispersion relation; which is obtained using the ballooning formalism. The TAE modes are characterized by a broad radial envelope, the width of which is independent on the mode number in the general case of monotonic equilibrium profiles. The results on the two-dimensional eigenmode structure are expected to be applicable to drift-type waves. The ballooning transform is generalized here to handle singular eigenfunctions typical of the continuous shear Alfven spectrum, and, thereby, facilitates the ...

Energy Technology Data Exchange (ETDEWEB)

This paper summarizes the current scientific evidence that improved indoor environmental quality can improve work performance and health. The review indicates that work and school work performance is affected by indoor temperature and ventilation rate. Pollutant source removal can sometimes improve work performance. Based on formal statistical analyses of existing research results, quantitative relationships are provided for the linkages of work performance with indoor temperature and outdoor air ventilation rate. The review also indicates that improved health and related financial savings are obtainable from reduced indoor tobacco smoking, prevention and remediation of building dampness, and increased ventilation. Example cost-benefit analyses indicate that many measures to improve indoor temperature control and increase ventilation rates will be highly cost effective, with benefit-cost ratios as high ...

International Nuclear Information System (INIS)

Co-current stratified flow of liquid metal and water was investigated in a horizontal rectangular channel. Position of the interface pressure drop and direct contact heat transfer between these immisci ble liquids were measured in a fully developed flow. A turbulence model was proposed to explain the experimental results considering that the turbulence is damped near the liquid-liquid interface by surface tension. The analytical results showed good agreement with the experimental ones. Main results are that (1) position of the interface mainly depends on the flow rate ratio of both liquids, that (2) the pressure drop is approximately proportional to square of the average velocity of water, and that (3) heat transfer rate at direct contact interface is several times higher than that of co-current flow separated by a thin solid plate. (author).

Energy Technology Data Exchange (ETDEWEB)

The field algebra of the minimal models of W-algebras is amenable to a very simple description as a polynomial algebra generated by a few elementary fields, corresponding to order parameters. Using this description, the complete Landau-Ginzburg lagrangians for these models are obtained. Perturbing these lagrangians we can explore their phase diagrams, which correspond to multicritical points with D[sub n] symmetry. In particular, it is shown that there is a perturbation for which the phase structure is similar to that of the IRF models of Jimbo et al. (orig.)

Energy Technology Data Exchange (ETDEWEB)

No abstract prepared.

International Nuclear Information System (INIS)

The research and development of a new type of high damping rubber damper for high rise buildings/structures to mitigate earthquake or wind-induced structural response is described in this paper. The static tests were carried out to investigate restoring force characteristics using scale model of high damping rubber damper. The repetitive tests and the temperature dependency tests were carried out to investigate variance of performance of energy absorption. It is confirmed that the damping force characteristics of the damper can be considered as that of linear viscous damping and the damper sufficiently dissipates energy for vibrations of mm order to that of generating 200% shear strain. The design methods, based on assuming linear viscous damping for the damper, has been developed. The designed values such as stiffness and damping coefficient of the damper agree ...

Energy Technology Data Exchange (ETDEWEB)

The temporal evolution of linear toroidal ion temperature gradient (ITG) modes is studied based on a kinetic integral equation including an initial condition. It is shown how to evaluate the analytic continuation of the integral kernel as a function of a complex-valued frequency, which is useful for analytical and numerical calculations of the asymptotic damping behavior of the ITG mode. In the presence of the toroidal {nabla}B-curvature drift, the temporal dependence of the density and potential perturbations consists of normal modes and a continuum mode, which correspond to contributions from poles and from an integral along a branch cut, respectively, of the Laplace-transformed potential function of the complex-valued frequency. The normal modes have exponential time dependence with frequencies and growth rates determined by the dispersion relation while the continuum mode, which has a ballooning structure, shows a power law decay ...

Energy Technology Data Exchange (ETDEWEB)

The two-dimensional WKB model has been the basis for several investigations of the quasi-Landau hydrogenic spectrum. Whereas other authors have used numerical integration, it is shown that the results can be obtained analytically in terms of elliptic integrals. The later are easily generated by even programmable pocket calculators, from which numerical results - which are in good agreement with experiments - are easily obtained. A further advantage of using elliptic integrals is that several strong-field problems can be shown to be special cases of a general potential whose energy and spacing are expressible in terms of them.

International Nuclear Information System (INIS)

Conventional methods for reducing vibration in engineering designs (i.e. by stiffening or detuning) may be undesirable or inadequate in conditions where size or weight must be minimized or where complex vibration spectra exist. Alloys which combine high damping capacity with good mechanical properties can provide attractive technical and economic solutions to problems involving seismic, shock and vibration isolation. To meet these trends, we have developed a new high damping Fe-17%Mn alloy. Also, the alloy has advantages of good mechanical properties and is more economical than any other known damping alloys (a quarter the cost of non-ferrous damping alloy). Thus, the high damping Fe-17%Mn alloy can be widely applied to household appliances, automobiles, industrial facilities and power plant components with its excellent damping capacity (SDC, 30%) and ...

Energy Technology Data Exchange (ETDEWEB)

The basic function of a Power System Stabilizer (PSS) is to add damping to the generator rotor oscillations by controlling its excitation using auxiliary stabilizing signals. To provide damping, the stabilizer must produce a component of electrical torque in phase with the rotor speed deviations. This paper introduces the hardware specifications and various functions of microprocessor (TMS320C32)-based digital PSS to provide the damping torque. (author). 3 refs., 6 figs.

Energy Technology Data Exchange (ETDEWEB)

This thesis deals with the reduced-order modeling of electrical machines and interconnected power systems in the medium time scale using integral manifold techniques. First, an improved model for power system stabilizer design that captures the damping due to the amortisseur windings while retaining the simplicity of the DeMello-Concordia model is presented. Second, time scales of the regulated synchronous machine are analyzed using the linearized models, and the well-known effects of the high-gain regulator on the system are explained. A reduced-order model that captures the damping due to the power-system stabilizer is presented. Third, speed-damping terms are obtained in the swing equation in a multimachine environment by approximating the integral manifold associated with fast damper windings. This provides a theoretical basis for the practice of adding cross-damping terms to the swing equation to ...

Energy Technology Data Exchange (ETDEWEB)

A characteristic trait of Francis turbines operating at low-head is pressure pulsations that occur during certain load levels of the generator. These stem from pressure variations across the turbine due to pulsating flow in the draft-tube. This surging action of the water column is related to draft-tube geometry and flow-rate of water in the penstock. The pressure pulsations cause torque variations on the turbine and corresponding electric power pulsations. If electric power is used as a feedback signal to the Power System Stabilizer (PSS), then Mvar and terminal voltage pulsations will occur when the generator is operating in the ``rough zone``. This paper describes field test results for investigating feedforward control from the penstock, draft tube and spiral case pressure to reduce the effects of Mw pulsations on PSS output signals. This investigation involved a PSS with generator power as the feedback signal and the PSS tuned for local and inter-area ...

CERN Document Server

A discrete time control algorithm using the damped least squares is introduced for acceleration and energy exchange controls in nonlinear vibrating systems. It is shown that the damping constant of least squares and sampling time step of the controller must be inversely related to insure that vanishing the time step has little effect on the results. The algorithm is illustrated on two linearly coupled Duffing oscillators near the 1:1 internal resonance. In particular, it is shown that varying the dissipation ratio of one of the two oscillators can significantly suppress the nonlinear beat phenomenon.

Science.gov (United States)

It is shown that the extended softening in k space of the [111] transverse acoustic phonon in Nb3Sn seen recently by neutron measurements is in agreement with the predictions of a phenomenological Landau description of the structural phase transition in the A-15 compounds. This indicates the feasibility of a calculation of the partial phonon density of states of modes directly coupled to the order parameter driving the structural transition, as a function of temperature.

Energy Technology Data Exchange (ETDEWEB)

Experimentally it is found that at constant temperature the order-parameter relaxation time, tausub(..delta..), decreases with increasing power of the microwaves, coupled into a superconducting strip. If the same increase in critical current, that corresponds with a given power of the microwaves, is obtained by lowering the temperature, the decrease in tausub(..delta..) is smaller. This reflects the fact that quasiparticles are removed more efficiently from the gap edge by microwaves than by lowering the temperature in equilibrium. A modified time-dependent Ginzburg-Landau equation is shown to describe these results adequately.

Energy Technology Data Exchange (ETDEWEB)

A micro-computer based fuzzy logic power system stabilizer is applied to a micro-machine system to investigate its efficiency in real time control. The stabilizing signal is determined by using measured speed or real power signals at every sampling time to damp the system oscillations. The results show the proposed stabilizer improves the system damping effectively subject to various types of disturbances.

Energy Technology Data Exchange (ETDEWEB)

This work presents a method to monitor the stability of a power system, after a major disturbance, using of adaptive time series approach. The model parameters are updated every time the prediction stage is completed. Besides, according to the values of the parameters, one may conclude the system will be unstable, will go to be a damped sine wave or even a damped exponential. (author) 29 refs., 12 figs., 3 tabs.

CERN Document Server

Observations show the ubiquitous presence of propagating magnetohydrodynamic (MHD) kink waves in the solar atmosphere. Waves and flows are often observed simultaneously. Due to plasma inhomogeneity in the perpendicular direction to the magnetic field, kink waves are spatially damped by resonant absorption. The presence of flow may affect the wave spatial damping. Here, we investigate the effect of longitudinal background flow on the propagation and spatial damping of resonant kink waves in transversely nonuniform magnetic flux tubes. We combine approximate analytical theory with numerical investigation. The analytical theory uses the thin tube (TT) and thin boundary (TB) approximations to obtain expressions for the wavelength and the damping length. Numerically, we verify the previously obtained analytical expressions by means of the full solution of the resistive MHD eigenvalue problem beyond the TT ...

International Nuclear Information System (INIS)

We theoretically model a nuclear-state preparation scheme that increases the coherence time of a two-spin qubit in a double quantum dot. The two-electron system is tuned repeatedly across a singlet-triplet level-anticrossing with alternating slow and rapid sweeps of an external bias voltage. Using a Landau-Zener-Stueckelberg model, we find that in addition to a small nuclear polarization that weakly affects the electron spin coherence, the slow sweeps are only partially adiabatic and lead to a weak nuclear spin measurement and a nuclear-state narrowing which prolongs the electron spin coherence. This resolves some open problems brought up by a recent experiment. We also show that the electronic two-spin states singlet and triplet T_+ are promising candidates for the implementation of a qubit in GaAs double quantum dots (DQD). A coherent superposition of the two-spin states is obtained by finite time Landau-Zener-Stueckelberg interferometry and ...

Energy Technology Data Exchange (ETDEWEB)

This paper reports that fluidelastic instability is the most important vibration excitation mechanism for heat exchanger tube bundles subjected to cross-flow. Most of the available data on this topic have been reviewed from the perspective of the designer. Uniform definitions of critical flow velocity for instability, damping, natural frequency and hydrodynamic mass were used. Nearly 300 data points were assembled. The authors found that only data from experiments where all tubes are free to vibrate are valid form a design point of view. In liquids, fluid damping is important and should be considered in the formulation of fluidelastic instability. From a practical design point of view, we conclude that fluidelastic instability may be expressed simply in term of dimensionless flow velocity and dimensionless mass-damping. There is no advantage in considering more sophisticated models at this time. Practical design guidelines ...

Energy Technology Data Exchange (ETDEWEB)

This paper deals with a robust H{sub -} power system stabilizer (HPSS) design using reduced-order models to improve the damping oscillation in power systems. The stabilizer is dynamic, low order and robust. In order to obtain a reduced-order controller, the method of balanced truncation is used. Sufficient conditions in the form of two algebraic Riccati equations (AREs) and an upper bound explicitly characterize an H{sub -} controller of lower dimensions. Furthermore, the bilinear transformation has been used to the design to prevent the pole-zero cancellation of the poorly damped poles and to improve the control system performance. The proposed technique is illustrated with applications to the design of stabilizer for a multi-machine power system. Simulation results under various operation conditions are given which show that the proposed HPSS damps the low-frequency oscillation in an efficient manner. (author)

International Nuclear Information System (INIS)

In order to investigate the systematics of the loop expansion in high temperature gauge theories beyond the leading order hard thermal loop (HTL) approximation, we calculate the two-loop electron proper self-energy #SIGMA# in high temperature QED. The two-loop bubble diagram of #SIGMA# contains a linear infrared divergence. Even if regulated with a nonzero photon mass M of order of the Debye mass, this infrared sensitivity implies that the two-loop self-energy contributes terms to the fermion dispersion relation that are comparable to or even larger than the next-to-leading order (NLO) contributions of the one-loop #SIGMA#. Additional evidence for the necessity of a systematic restructuring of the loop expansion comes from the explicit gauge-parameter dependence of the fermion damping rate at both one and two loops. The leading terms in the high temperature expansion of the two-loop self-energy for all topologies arise from an explicit ...

CERN Document Server

It is shown that the physical interpretation of Elie Cartan three-dimensional space torsion as couple asymmetric stress, has the effect of damping, previously Riemannian unstable Couette planar shear flow, leading to stability of the flow in the Lagrangean sense. Actually, since the flow speed is inversely proportional to torsion, it has the effect of causing a damping in the planar flow atenuating the instability effect. In this sense we may say that Cartan torsion induces shear viscous asymmetric stresses in the fluid, which are able to damp the instability of the flow. The stability of the flow is computed from the sectional curvature in non-Riemannian three-dimensional manifold. Marginal stability is asssumed by making the sectional non-Riemannian curvature zero, which allows us to determine the speeds of flows able to induce this stability. The ideas discussed here show that torsion plays the geometrical role of ...

Energy Technology Data Exchange (ETDEWEB)

The paper reported on an experiment on measurement of concentration of highly concentrated coal slurry using microwaves carried out at Miike coal preparation works. The purpose of the experiment was to investigate applicability of microwave moisture content measurement of slurry of a mixture of coal and coal particles and to use it to the control of process such as coal preparation and processing. In the experiment, a method for measuring the slurry concentration was adopted in which the container filled with highly concentrated coal slurry was irradiated with microwaves and the damping of strength of the penetrating microwaves was detected. As a result of the experiment, it was found out that there was a big correlation between the capacitive concentration of slurry and the damping ratio of microwaves. When irradiating slurry with microwaves of 1GHz frequency, a big correlation between the concentration and the damping ...

CERN Document Server

We present a dynamical spectral model for Large Eddy Simulation of the incompressible magnetohydrodynamic (MHD) equations based on the Eddy Damped Quasi Normal Markovian approximation. This model extends classical spectral Large Eddy Simulations for the Navier-Stokes equations to incorporate general (non Kolmogorovian) spectra as well as eddy noise. We derive the model for MHD and show that introducing a new eddy-damping time for the dynamics of spectral tensors in the absence of equipartition between the velocity and magnetic fields leads to better agreement with direct numerical simulations, an important point for dynamo computations.

Energy Technology Data Exchange (ETDEWEB)

The underlying theory and model of capacitive voltage substations and its associated problems are described. This system is intended to supply electricity to rural communities directly from high-voltage transmission lines. This technique leads to important cost reductions when compared with conventional alternatives. However, in several transient cases, some problems such as ferroresonance and overvoltages could occur in these substations. Using a developed capacitive substation model these transient cases are simulated. A suitable filter is designed to damp overvoltages clue to ferroresonance. Analytical aspects of filter design are presented and some computer simulation tests are provided to highlight the usefulness of the proposed filter. (author)

International Nuclear Information System (INIS)

We consider a SQUID ring inductively coupled to an electromagnetic field mode, both treated quantum mechanically. We demonstrate a method for creating a maximally entangled state between the ring and the field mode. Our method utilises a non-adiabatic external magnetic flux pulse to move into and out of a transition region. Hence, our approach is fundamentally different to techniques based on Landau-Zener tunnelling that can also be used to achieve similar results. Our analysis is extended to include the effects of coupling the system to a dissipative environment. With this model we show that although such an environment makes a noticeable difference to the time evolution of the system, it need not destroy the entanglement of this coupled system over time scales required for quantum technologies.

CERN Document Server

It is a pity that the real state of matter in pulsar-like stars is still not determined confidently because of the uncertainty about cold matter at supranuclear density, even 40 years after the discovery of pulsar. Nuclear matter (related to neutron stars) is one of the speculations for the inner constitution of pulsars even from the Landau's time more than 70 years ago, but quark matter (related to quark stars) is an alternative due to the fact of asymptotic freedom of interaction between quarks as the standard model of particle physics develops since 1960s. Therefore, one has to focus on astrophysical observations in order to answer what the nature of pulsars is. In this presentation, I would like to summarize possible observational evidence/hints that pulsar-like stars could be quark stars, and to address achievable clear evidence for quark stars in the future experiments.

International Nuclear Information System (INIS)

In this paper, 0.75Pb(Fe2/3W1/3)O3-0.25PbTiO3-0.15 wt% MnO (0.75PFW-0.25PT-0.15 wt% MnO) ceramics are synthesized by two different methods, the conventional direct oxide synthesized (DS) method and two-step indirect synthesized (IS) method. The low-field dielectric responses are investigated by using the empirical law, the Curie-Weiss law, the modified-Landau theory and the spin-glass model. Due to the IS method, the lattice structure and the grain structure of the samples are changed. Furthermore, the dielectric properties are evidently modified. It is suggested that the ordering degree of B-site cations is enhanced by using the IS synthesized method.

CERN Document Server

Two-dimensional simulations of the coarsening process of the isotropic/smectic-A phase transition are presented using a high-order Landau-de Gennes type free energy model. Defect annihilation laws for smectic disclinations, elementary dislocations, and total dislocation content are determined. The computed evolution of the orientational correlation length and disclination density is found to be in agreement with previous experimental observations showing that disclination interactions dominate the coarsening process. The mechanism of smectic disclination movement, limited by the absorption and emission of elementary dislocations, is found to be facilitated by curvature walls connecting interacting disclinations. At intermediate times in the coarsening process, split-core dislocation formation and interactions displaying an effective disclination quadrupole configuration are observed. This work provides the framework for further understanding of the formation and ...

Energy Technology Data Exchange (ETDEWEB)

We study the localized tachyon condensation of non-supersymmetric orbifold backgrounds in their mirror Landau-Ginzburg picture. We first show that the R-charges of chiral primaries increase under the process of condensing the tachyon in the same chiral ring. Then, utilizing the existence of four copies of (2,2) worldsheet supersymmetry, we show that the minimal tachyon mass in twisted sectors increases in CFT and type 0 string and it plays the role of the c-function of the twisted sectors. We also study the GSO projection in detail and show that type II decays to only to type II while type 0 can mix with type 0 and II under the RG-flow.

Energy Technology Data Exchange (ETDEWEB)

Recently, the development of shape memory alloy (SMA) actuators, in the forms of wire, thin film and stent have been found increasingly in the fields of materials science and smart structures and engineering. The increase in attraction for using these materials is due to their many unique materials, mechanical, thermal and thermal-mechanical properties, which in turn, evolve their subsequent shape memory, pseudo-elasticity and super-elasticity properties. In this paper, a common type of SMA actuator, Nitinol wires, were embedded into advanced composite structures to modulate the structural dynamic responses, in terms of natural frequency and damping ratio by using its shape memory and pseudo-elastic properties. A simple theoretical model is introduced to estimate the natural frequency of the structures before and after actuating the embedded SMA wires. The damping ratios of different SMA composite beams were measured through experimental ...

CERN Document Server

Within a fully relativistic framework, we derive and solve numerically the perturbation equations of relativistic stars, including the stresses produced by a non-vanishing shear viscosity in the stress-energy tensor. With this approach, the real and imaginary parts of the frequency of the modes are consistently obtained. We find that, approaching the inviscid limit from the finite viscosity case, the continuous spectrum is regularized and we can calculate the quasi-normal modes for stellar models that do not admit solutions at first order in perturbation theory when the coupling between the polar and axial perturbations is neglected. The viscous damping time is found to agree within factor 2 with the usual estimate obtained by using the eigenfunctions of the inviscid limit and some approximation for the energy dissipation integrals. We find that the frequencies and viscous damping times for relativistic $r-$modes lie between the Newtonian and ...

CERN Document Server

While radiation-pressure cooling is well known, the Brillouin scattering of light from sound is considered an acousto-optical amplification-only process. It was suggested that cooling could be possible in multi-resonance Brillouin systems when phonons experience lower damping than light. However, this regime was not accessible in traditional Brillouin systems since backscattering enforces high acoustical frequencies associated with high mechanical damping. Recently, forward Brillouin scattering in microcavities has allowed access to low-frequency acoustical modes where mechanical dissipation is lower than optical dissipation, in accordance with the requirements for cooling. Here we experimentally demonstrate cooling via such a forward Brillouin process in a microresonator. We show two regimes of operation for the Brillouin process: acoustical amplification as is traditional, but also for the first time, a Brillouin cooling regime. Cooling is ...

Energy Technology Data Exchange (ETDEWEB)

A brief summary of the theory and experiments on electron- cyclotron heating and current drive is presented. The general relativistic formulation of wave propagation and linear absorption is considered in some detail. The O-mode and the X-mode for normal and oblique propagation are investigated and illustrated by several examples. The experimental verification of the theory in T-10 and D- III-D is briefly discussed. Quasilinear evolution of the momentum distribution and related applications as, for instance, non linear wave, damping and current drive, are also considered for special cases of wave frequencies, polarization and propagation. In the concluding section we present the general formulation of the wave damping and current drive in the absence of electron trapping for arbitrary values of the wave frequency. (Author) 13 refs.

CERN Document Server

Magnetic fields appear to be a generic feature of the early universe and are a natural source of secondary CMB non-Gaussianity. In recent years the statistical nature of the stresses of a primordial magnetic field has been well studied. In this paper we confirm and extend these studies at one- and two-point level, and present analytical results for a wide range of power-law spectra. We also consider two non-power law cases of interest: a blue spectrum with an extended damping tail on small scales, which could be generated by the non-linear mixing of density and vorticity; and a red spectrum with a damping tail on large scales. We then briefly consider the CMB impacts that result from such fields. While this paper focuses on the one- and two-point moments, the techniques we employ are designed to ease the analysis of the full bispectra induced by primordial magnetic fields.

Energy Technology Data Exchange (ETDEWEB)

Large-eddy-simulations are performed for the heat transfer and the wake flow of a thin rotating disk subjected to an outer parallel passing stream of air. Above a critical value for the angular velocity of the disk, heat transfer augmentation sets on. This is strongly related to a flow instability that leads to a periodic vortex generation at the counter-moving disk side. The resulting phenomena are captured by the classical Landau model. For higher angular velocities the wake becomes fully turbulent, and here the transition to turbulence seems to be very abrupt. In this regime, a periodic vortex generation is observable at the co-moving disk side, too. (orig.) [German] Grobstruktur-Simulationen werden fuer die Waermeuebertragung und die Nachlaufstroemung fuer eine duenne rotierende Scheibe in einem aeusseren parallelen Luftstrom durchgefuehrt. Oberhalb eines kritischen Wertes fuer die Rotationsgeschwindigkeit setzt eine Verstaerkung der Waermeuebertragung ein. ...

Energy Technology Data Exchange (ETDEWEB)

A decoupled characteristic between the damping of a specific swing mode and the stabilizer gain of the corresponding machine in multimachine power systems is identified. Using this decoupled characteristic a power system stabilizer (PSS) synthesis approach which is based on the phase compensation concept is verified on a 9-machine system and the dynamic performance of this system is significantly improved. This method is proved to be effective, simple and it can provide useful guidance for the PSS field tuning.

Energy Technology Data Exchange (ETDEWEB)

This paper is concerned with the application of a new fuzzy inference method to the design of fuzzy power system stabilizer. Based on Truth-Value-Flow-Inference (TVFI), a fuzzy logic controlled power system stabilizer is proposed to enhance the stability of power system with weak or negative damping. The design of the proposed fuzzy power system stabilizer is presented. Numerical simulation results are presented and compared with two other kinds of fuzzy power system stabilizers. (author)

Energy Technology Data Exchange (ETDEWEB)

A mathematical model of the multi machine electric power system to analyse its dynamics has been worked out. The effectivity of the power system stabilizer developed in the one machine system has been tested by means of this model. The influence of the arrangement of the stabilizers on the stability of the electric power system has also been investigated. High damping of electromechanical transient processes has been achieved. 7 refs., 1 tab., 5 figs.

Energy Technology Data Exchange (ETDEWEB)

The paper presents a sequential procedure for coordinated stabilization of a multimachine power system with arbitrary complexity of the system model. The most effective machine to be equipped with a power system stabilizer is identified using eigenvalue analysis. The selection is based on the sensitivity of critical eigenvalues to increases in the coefficient of a damping term which is inserted in each equation of motion, in succession. The method is applied to a three-machine system and simulation studies show appreciable improvements in the small disturbance stability of the system.

Energy Technology Data Exchange (ETDEWEB)

An integrated voltage regulator and power system stabilizer based on one step ahead prediction is presented. The fixed parameter predictive control scheme is shown capable of providing consistently good voltage response and contribution to system damping over a wide range of operating conditions and system configuration. This is in contrast to the case with conventional automatic voltage regulator and power system stabilizer where performance varies widely with the operating situation and can even cause system instability. (author)

Energy Technology Data Exchange (ETDEWEB)

Visual excitation is initiated by the absorption of a photon by the 11-cis retinal chromophore bound within the pigment called rhodopsin. We have used a variety of vibrational spectroscopies to obtain information about the vibrational nuclear dynamics that lead to this efficient photochemical isomerization. The cis-trans isomerization in rhodopsin is complete in only 200 fs. The extreme speed of this process, which is consistent with the {approximately}50 fs lifetime indicated by the spontaneous emission yield, suggests that the photochemistry involves non-stationary states or vibrational coherence. Recent studies have in fact observed vibrationally coherent oscillations of the ground state photoproduct called bathorhodopsin following impulsive excitation of the rhodopsin reactant. This conclusively demonstrates that the isomerization process in rhodopsin is vibrationally coherent. These observations further suggest that the isomerization quantum yield is directly dependent on the ...

Energy Technology Data Exchange (ETDEWEB)

Ammonia borane (AB) and sodium borohydride (SBH) are candidate materials for on-board hydrogen storage that can be dehydrogenated upon demand. The rheological properties of the dehydrogenated by-products are important to quantify their removal and transportability from the hydrogen storage system. This paper presents visco-elastic property (elastic stiffness and viscous damping) measurements of the spent fuels obtained from AB hydrolysis, hydrothermolysis and thermolysis; and SBH hydrolysis. Smaller stiffness and larger mobility (or smaller viscous damping) indicate better transportability of the spent fuel. In addition, flow property (dynamic angle of repose and avalanching time) measurements for the hydrolysis spent fuels of AB and SBH are also presented. Comparing with the SBH hydrolysis spent fuel, the AB hydrolysis spent fuel had a lower stiffness and larger mobility, as well as lower angles of dynamic repose and avalanche power peaks, ...

British Library Electronic Table of Contents (United Kingdom)

Effects of soil pH on damping-off of sugar beet by R. solani (AG2-2) and soil suppressiveness against the disease were studied by comparing disease incidences in pasteurized versus non-pasteurized, infested soils. Soil pH was correlated neither to disease incidence in five soils ranging from pH?4.5 to 7.2 nor to indigenous disease suppressiveness, the difference in disease incidences between non-treated soil and its pasteurized counterpart. When an alkaline soil was acidified with H2SO4, disease suppression markedly declined, increasing disease incidence in the non-pasteurized soil. Inversely, disease suppression was enhanced when an acidic soil was neutralized by adding Ca(OH)2. Soil amendment with dried peanut plant residue suppressed the disease in two pasteurized, near-neutral soils, l...

Energy Technology Data Exchange (ETDEWEB)

The paper describes the application of Fuzzy Power System Stabilizer(FPSS) for improving dynamic stability of power system. The Real-coding Genetic Algorithm(RGA) was applied to optimize gains of the inputs and outputs of the FPSS. The effectiveness of the proposed FPSS was demonstrated by simulation studies for single-machine infinite system. To show the superiority of the proposed FPSS, its performances were compared with those of Conventional Power System Stabilizer (CPSS). The proposed FPSS showed better control performances than the CPSS in three-phase ground fault under a normal load which was system condition in tuning FPSS. To show the robustness of the proposed FPSS, it was applied to damp the low frequency oscillations caused by disturbances such as three-phase ground fault under heavy and light load conditions. The proposed FPSS showed better performance than CPSS in terms of the settling time and damping effect for power system ...

International Nuclear Information System (INIS)

In the decoupling limit M_A_"0"2>>M_Z"2, the heavy CP-even, CP-odd, and charged Higgs boson masses are nearly degenerate, sin(#beta#-#alpha#) approaches 1, and the lightest CP-even Higgs boson almost displays the same properties as the standard model Higgs boson. But the top and bottom squark sectors can change this pattern through radiative corrections. We find that there are parameter regions at small and moderate tan #beta# in the minimal supersymmetry standard model under experimental constraints of (g-2)_#mu#, b#->#s#gamma#, and lower bounds of Higgs boson and sparticle masses, where sin"2(#beta#-#alpha#) is damped (say below 0.8), which has a significant effect on Higgs couplings g_h_"0_V_V(V=W"#+-#,Z"0) and g_h_"0_#gamma#_#gamma#. We discuss its impact on the lightest CP-even Higgs boson production at #gamma##gamma# colliders.

British Library Electronic Table of Contents (United Kingdom)

We apply the group theory to Kadomtsev-Petviashvili-Burgers (KPBII) equation which is a natural model for the propagation of the two-dimensional damped waves. In correspondence with the generators of the symmetry group allowed by the equation, new types of symmetry reductions are performed. Some new exact solutions are obtained, which can be in the form of solitary waves and periodic waves. Specially, our solutions indicate that the equation may have time-dependent nonlinear shears. Such exact explicit solutions and symmetry reductions are important in both applications and the theory of nonlinear science.

Energy Technology Data Exchange (ETDEWEB)

In this paper, power system stabilizer design for multi-machine power systems is translated into an equivalent problem of decentralized controller design for Multi-Output Multi-Input (MIMO) control systems. Subject to a condition based on the structured singular values, each stabilizer can be designed independently. Within this general framework, the conventional stabilizer design methodology based on the concept of synchronous and damping torques is used to decide the design details of each stabilizer. The suggested design method is applied to a model of a practical 10 machine power system. (author)

Energy Technology Data Exchange (ETDEWEB)

The damping of unwanted oscillations in the generator units after a failure can be realized by installing a stabilizer between f.e. the revs of the generator and an input of the voltage regulator. The tuning of a Power System Stabilizer (PSS) is investigated using bode plots. Eigenvalue analysis shows an enlarged system stability margin. The method was tested on an advanced analogue power system simulator. As a result of these tests it appears to be useful to consider the stability as well as the optimal tuning. 5 figs., 6 refs.

Energy Technology Data Exchange (ETDEWEB)

Westinghouse Electric Germany GmbH has developed fluid dynamic models for medium-actuated armatures using the thermal hydraulic code RELAP5 in order to reach a more realistic description of the armature behavior including fluid-structure interactions in case of transient flow conditions in piping systems. The contribution is concerned with the modeling of damped check valves. The model allows the description of the behavior during opening and closure of a check armature. The calculated results show good agreement with the available measured data.

International Nuclear Information System (INIS)

Argon ion laser induced fluorescence measurements were carried out in a multipolar filament discharge with a broadband diode laser centered on 668 nm, which stimulated a transition from the metastable state in Ar(II) 3d4F7/2 to 4p4D05/2. The intensity of the induced fluorescence at 442 nm was maximized by the optimization of the discharge parameters and the laser power. From the recovery of the background fluorescence after the laser was turned off, the ion diffusion coefficient was deduced and compared with the result inferred from the experiments of ion acoustic wave (IAW) damping.

Energy Technology Data Exchange (ETDEWEB)

A self-tuning PID (proportional-integral-derivative) power system stabilizer (PSS) is presented for improving the dynamic stability of a multimachine power system over a wide range of operating conditions. In order to maintain good damping characteristic when there is a drastic change in system operating condition, the gain settings are adapted in real time based on the continuously measured system inputs and outputs. The proposed self-tuning stabilizer has a decentralized structure and only local measurements within each generating units are required for the adaptation process. The effectiveness of the proposed stabilizer is demonstrated by an example.

Energy Technology Data Exchange (ETDEWEB)

Horizontal vibrations of elevator cars mainly occur because a car swings as roller guides installed at corners of a car frame move on a winding guide rail at high speeds. Rider comfort in high speed elevators is worsened by these vibrations. Conventional active dampers suppressing horizontal vibrations using ac servo motors make cars heavier so driving power becomes larger, and they are not easily applied to existing elevators. An active damping control method suited to super-high-speed elevators is which can solve these problems. The method suppresses vibrations by generating only enough magnetic force needed to suppress them only when vibrations of the car franc are produced. The vibrations are detected using acceleration detectors and magnets installed on left and right sides of the car frame. A computer simulator was made to analyze phenomena of car vibrations and to verify effects of the proposed magnetic damping controller. It was found ...

Energy Technology Data Exchange (ETDEWEB)

Magnesium alloys are being increasingly utilized in a variety of fields as an alternative material to organic materials and aluminum alloys, owing to excellent properties. Those include low density, and excellent damping properties. When compared to organic materials, furthermore, Mg alloy excels at recyclability, heat radiation, and electromagnetic-shielding. Though most of magnesium alloy products are manufactured through die-casting and thixo-molding at present, the demand for the expanding of magnesium wrought alloy market is increasing. Taking full advantage of a drawing technique and applying it to the conventional extruded pipe, we have developed a new type of magnesium alloy pipe. The strength of the developed pipe is significantly higher than that of the conventional one, either extruded or die-casting. Some of the excellent properties were obtained from fundamental tests performed with the developed pipe. Both tensile properties and bending formability ...

Energy Technology Data Exchange (ETDEWEB)

The elastic behaviour of YBaCuO specimens has been studied by very low-frequency isothermal internal-friction measurements. A relaxation peak is observed which is attributed to oxygen atom jumps, between A(1/2 0 0) and B(0 1/2 0) sites, in the CuO planes of the orthorhombic phase. A limit relaxation time {tau}{sub 0}, 2.6 {center dot} 10{sup -15}s, and an activation energy, 1.3eV, have been obtained from the shift of the maximum damping frequency observed when the measurement temperature is changed. The proposed values for the limit relaxation time and the activation energy are in good agreement with those previously proposed in the literature.

International Nuclear Information System (INIS)

The effects of vibration isolation of the new type of mechanical damper applied to a single-degree-of-freedom system and a simple beam are discussed numerically and experimentally. The damper is composed of a ball screw, a flywheel and centrifugal brakes, and possesses nonlinear characteristics. The Continuous System Simulation Language is used for the digital simulations of the nonlinear vibration systems. The results may be summarized as follows: (1) The damper is effective for suppressing the amplitude of the single-degree-of-freedom system as well as of the beam at the point of attachment of the damper, at the resonances. (2) The damper approaches a snubber for smaller values of lead L of the ball screw (or larger values of moment of inertia J of the flywheel), and acts like a damper whose damping force is proportional to the square of the velocity for larger values of L (or smaller values of J). (author).

CERN Document Server

In the beam pipe of the positron damping ring of the Next Linear Collider, electrons will be created by beam interaction with the surrounding vacuum chamber wall and give rise to an electron cloud. Several solutions are possible for avoiding the electron cloud, without changing the bunch structure or the diameter of the vacuum chamber. Some of the currently available solutions for preventing this spurious electron load include reducing residual gas ionization by the beam, minimizing beam photon-induced electron production, and lowering the secondary electron yield (SEY) of the chamber wall. We will report on recent SEY measurements performed at SLAC on TiN coatings and TiZrV non-evaporable getter thin films.

Science.gov (United States)

The transport of magnetospheric particles in the outer cusp region is examined by means of three-dimensional single particle codes. It is shown that, at high altitudes, particles can experience nonadiabatic motions leading to significant magnetic moment changes. It is demonstrated that this nonadiabatic behavior can be interpreted, at least partly, by the action of an impulsive centrifugal force perturbing the particle gyromotion. Systematic trajectory calculations reveal that plasma sheet ions which ExB convert toward the magnetopause from low L-shells in the dayside sector are subjected to such nonadiabatic motions. As a result of magnetic moment damping, a number of them are injected into the loss cone and subsequently precipitate near the cusp equatorward edge.

Energy Technology Data Exchange (ETDEWEB)

This book presents the proceedings of a conference dedicated to the design and operation of pipework in all its aspects, involving both metallic and non-metallic materials. Topics considered include a study of single mitre pipe bends using the finite element method; tests to failure of GRP pipe bends under in-plane flexural loading; finite element stress analysis of an equal diameter branch pipe intersection subjected to internal pressure and in-plane moment loadings; finite element stress analysis of extruded outlet tee junctions; design of pipework on the British PWR; a review of advanced remanent life methods for pipes operating in the creep range; pipe whip analysis and design; damping values for piping systems; pipework snubbers based on electro-rheological fluids; and the seismic design of piping systems in the flexible range.

CERN Document Server

We consider various modifications of the Weyl-Moyal star-product, in order to obtain a finite range of nonlocality. The basic requirements are to preserve the commutation relations of the coordinates as well as the associativity of the new product. We show that a modification of the differential representation of the Weyl-Moyal star-product by an exponential function of derivatives will not lead to a finite range of nonlocality. We also modify the integral kernel of the star-product introducing a Gaussian damping, but find a nonassociative product which remains infinitely nonlocal. We are therefore led to propose that the Weyl-Moyal product should be modified by a cutoff like function, in order to remove the infinite nonlocality of the product. We provide such a product, but it appears that one has to abandon the possibility of analytic calculation with the new product.

Energy Technology Data Exchange (ETDEWEB)

Dynamic stability enhancement of composite mode oscillations of interconnected power systems by means of a hybrid power system stabilizer is discussed here. The proposed Hybrid PSS is of a two-level structure composed of a local PSS for local mode and a global PSS for inter-area mode damping. Here, the input of the global stabilizer is the center of inertia speed deviation of slow-coherent generators. The paper is focused on the practical considerations in implementation of the proposed stabilizer. First, the optimum allocation of this stabilizer is discussed. The authors introduce an index of mode-input-assignability, by which the best sites of the stabilizer can be identified. Next, for practical applications, an estimation method for the approximation of the input of the global PSS is introduced. An approximated value of the center of inertia speed is obtained from a suitable combination of the rotor speed data of a few properly selected key generators.

International Nuclear Information System (INIS)

This paper reviews generation methods of artificial earthquake motion and proposes an improved method of generating input motions for use in vibration tests of equipment to prove aseismic performance. The improved method employs beat wave repetition characteristic that inherently appears in the component waves of recorded earthquakes decomposed by bandpass filter and algebraic function phase for the component waves. Typical motions generated by the improved method satisfies prescribed severe conditions such as target response spectrum that are defined with a wideband frequency component and a limited maximum acceleration due to shaking table performance. The motions had never been generated by the conventional method.

Energy Technology Data Exchange (ETDEWEB)

The alpha-particle confinement of future D-T experiments at JET can be severely degraded by Global Alfven Eigenmodes (AE). Scenarios for the excitation of Alfven Eigenmodes in usual (e.g. D-D) plasmas are proposed, which provide a MHD diagnostic and allow the study of the transport of super-Alfvenic ions. Active studies with separate control of TAE amplitude and energetic particle destabilization, measuring the plasma response, give more information than passive studies, in particular concerning the damping mechanisms. The TAE excitation can be achieved by means of the saddle coil and the ICRH antenna. The experimental method is introduced together with a theoretical model for RF excitation. (authors). 6 refs., 3 figs.

Energy Technology Data Exchange (ETDEWEB)

This paper presents a new method for simultaneously selecting the power system stabilizer (PSS) parameters in multimachine power systems. Design of local output feedback power system stabilizer using local signal of the generator (e.g. speed or power) is formulated as a decentralized modal control (DMC) problem. Exact model reduction based on modal control theory is proposed to make the determination of PSS parameters highly efficient. Results obtained from the coordinated tuning of the parameters of three power system stabilizers equipped on a multimachine power system show that exact assignment of the eigenvalues associated with the poorly damped electromechanical modes can be achieved in a very efficient manner.

Energy Technology Data Exchange (ETDEWEB)

An artificial neural network (ANN), trained as an inverse of the controlled plant, to function as a power system stabilizer (PSS) is presented in this paper. In order to make the proposed ANN PSS work properly, it was trained over the full working range of the generating unit with a large variety of disturbances. Data used to train the ANN PSS consists of the control input and the synchronous machine response with an adaptive PSS (APSS) controlling the generator. During training, the ANN was required to memorize the reverse input/output mapping of the synchronous machine. After the training, the output of the synchronous machine was applied as the input of the ANN PSS and the output of the ANN PSS was used as the control signal. Simulation results show that the proposed ANN PSS can provide good damping of the power system over a wide operating range and significantly improve the system performance.

British Library Electronic Table of Contents (United Kingdom)

In this work, a powerful analytical method, called He's parameter-expanding methods (HPEM) is used to obtain the exact solutions of non-linear modified Van der Pol's oscillator. The classical Van der Pol equation with delayed feedback and a modified equation where a delayed term provides the damping are considered. It is shown that one term in series expansions is sufficient to obtain a highly accurate solution, which is valid for the whole solution domain. Comparison of the obtained solution with those obtained using perturbation method shows that this method is effective and convenient to solve this problem. This method introduces a capable tool to solve this kind of non-linear problems.

Science.gov (United States)

A model is presented for describing the Amputee Independent Prosthesis Properties (AIPP) of complete assemblies of trans-tibial prosthetic components distal to the socket. This new AIPP model includes features of both lumped parameter and roll-over models and describes prosthesis properties that are of importance in stance phase, including prosthetic foot geometry, normal stiffness, shear stiffness, and damping (energy dissipation). Methods are described for measuring the parameters of the AIPP model using a custom test-rig, commercial load-cell, and a motion capture system. Example data are presented for five pylon angles reflecting the shank angles seen in normal gait. Through the inclusion of measured AIPP in future in-vivo studies comparing different prostheses more generic information, as opposed to product specific claims, will become more widely available to inform future designs, prescription, and alignment procedures. PMID:21831379

Energy Technology Data Exchange (ETDEWEB)

A power system stabilizer based on GMV (Generalized Minimum Variance), one of the adaptive control techniques, is developed to enhance the dynamic performances of a power system using an Artificial Neural Network (ANN). The stabilizer consists of two parts. One part is Inverse Dynamics Neural Networks (IDNN), which is trained to identify the inverse dynamics of controlled plant and used as a one-step ahead controller, or inverse controller. The other part is Adaptive Reference Model (ARM), which prevents excessive controller output. The ARM produces the modified reference value by minimizing a cost function recursively on the assumption that the IDNN perfectly identifies the controlled plant. The IDNN is used in the minimization procedure to calculate the sensitivities. The proposed controller is simulated in a typical one-machine-infinite-bus power system to show its effectiveness to damp sustained low frequency oscillation. (author)

Energy Technology Data Exchange (ETDEWEB)

This paper presents a design of fuzzy power system stabilizer (FPSS) using adaptive evolutionary computation (AEC). We have proposed an adaptive evolutionary algorithm which uses a genetic algorithm (GA) and an evolution strategy (ES) in an adaptive manner in order to take merits of two different evolutionary computations. FPSS shows better control performances than conventional power system stabilizer (CPSS) in three-phase fault with heavy load which is used when tuning FPSS. To show there robustness of the proposed FPSS, it is applied to damp the low frequency oscillations caused by disturbances such as three-phase fault with normal and light load, the angle deviation of generator with normal and light load and the angle deviation of generator with heavy load. Proposed FPSS shows better robustness than CPSS. (author). 15 refs., 13 figs., 3 tabs.

International Nuclear Information System (INIS)

A formalism for the dynamical treatment of the molecular orbitals of valence nucleons in nucleus-nucleus collisions is developed with the use of the coupled-reaction-channel (CRC) method. The Coriolis coupling effects as well as the finite mass effects of the nucleon are taken into account in this model, of rotating molecular orbitals, RMO. First, the validity of the concept is examined from the viewpoint of the multi-step processes in a standard CRC calculation for systems containing two identical [core] nuclei. The calculations show strong CRC effects particularly in the case where the mixing of different l-parity orbitals - called hybridization in atomic physics - occurs. Then, the RMO representation for active nucleons is applied to the same systems and compared to the CRC results. Its validity is investigated with respect to the radial motion (adiabaticity) and the rotation of the molecular axis (radial and rotational coupling). Characteristic molecular orbitals of covalent ...

International Nuclear Information System (INIS)

The International Atomic Energy Agency has initiated a co-ordinated research programme on implementation of base-isolation for nuclear structures. This paper discusses two areas relevant to modelling elastomeric base-isolators. These are the use of simplified models to predict the response of isolated structures to earthquake inputs and finite element analysis for calculating the stress distributions within the isolators. In the former, a curvilinear hysteretic model of the high damping natural rubber able to accommodate the stiffening of the rubber at large shear deflections is presented. Its predictions of structural accelerations and bearing displacement produced by design earthquakes and those above the design level are compared with those using a linear spring and dashpot model. A comparison has been made between two finite element analyses using MARC and ABAQUS of the force-deformation behaviour of a single disc of rubber bonded on both sides. The disc was ...

International Nuclear Information System (INIS)

A series of Model Tests of Embedment Effect on Reactor Buildings has been carried out by the Nuclear Power Engineering Corporation (NUPEC), under the sponsorship of the Ministry of International Trade and Industry (MITI) of Japan. Reactor buildings in Japan are partially embedded in general. Therefore, it is important to know how partial embedment affects the vibration characteristics of reactor buildings relating to seismic safety. Laboratory tests were conducted using a ground model made of silicone rubber (Young's modulus 2.3x10"6 Pa, Poisson's ratio 0.484, Density 1.24x 10"3 kg/m3 , Damping ratio 0.01) and a foundation model made of aluminum shown to study the effects of embedment on soil-structure interaction with different backfill types. The ground model is a cylinder, 70 cm high and 300 cm in diameter, with pit where the parallelepiped foundation model with square plan of 30 cm x 30 cm and 18 cm high was placed. Four types of backfill of silicone rubber ...

Energy Technology Data Exchange (ETDEWEB)

No abstract prepared.

Energy Technology Data Exchange (ETDEWEB)

A remarkably simple argument successfully accounts for the rate of star formation in different galaxies. The snag is that the timescale is uncomfortably short.

Energy Technology Data Exchange (ETDEWEB)

The central aim of this thesis is to present a new kind of realism that is driven not from the traditional realism/anti-realism debate but from the practice of physicists. The usual debate focuses on discussions about the truth of theories and their fit with nature, while the real practices of the scientists are forgotten. The position I shall defend is called 'phenomenological realism': theories are merely tools to construct other theories and models, including phenomenological models; phenomenological models are the vehicles of representation. The realist doctrine was recently undermined by the argument from the pessimistic meta-induction, also known as the argument from scientific revolutions. I argue that phenomenological realism is a new kind of scientific realism which can overcome the problem generated by the argument from scientific revolutions, and which depend on the scientific practice. The realist tried to overcome this problem by suggesting various types ...

Energy Technology Data Exchange (ETDEWEB)

VSP data are usually recorded in common-shot gather and contain less informations. It is difficult, therefore, to obtain good migration result by using conventional migration methods. Both inner interface reflections and interformational multiples can be removed by reverse-time migration with the use of two-way nonreflection wave equation: besides, boundary reflection in VSP can be eliminated using Clayton's absorption boundary condition. It is proved that reverse-time migration is able to improve migration quality. The imaging condition is still obtained by generalizing Claerbout's imaging principle and solving eikonal equation. This is a very practical wave equation migration method. This method is applicable to prestack VSP data, conventional multiple-offset shot gather and the simultaneous migration of VSP data and surface seismic data. Besides, it is adaptable to various velocity variations. Before applying the method to VSP data processing, one should finish the ...

Science.gov (United States)

% In this work we investigated, in the Smooth Particle Hydrodynamics (SPH) framework, the development of spiral structures and shock fronts in the radial flow of accretion discs in close binary systems. These shock waves take place when the initially supersonic radial flow penetrating the disc bulk, reduces substantially its speed becoming suddenly subsonic. To this purpose, keeping constant the mass of the compact primary (M1 = 1 MO ), the separation between the two components and the injection speed at the inner Lagrangian point L1 (close to the local sound speed), we carried out 2D SPH simulations for four values of the stellar mass ratio M2/M1. We worked out 2D models because the damping effect of the artificial viscosity is too strong in 3D. Furthermore, the 2D environment seems the most suitable in order to evidence shock fronts in highly compressible gases. The results show that spiral structures and shock fronts develop for low values of M2/M1, whilst they ...

Energy Technology Data Exchange (ETDEWEB)

A pole placement technique for power system stabilizer (PSS) and thyristor controlled series capacitor (TCSC) based stabilizer using simulated annealing (SA) algorithm is presented in this paper. The proposed approach employs SA optimization technique to PSS (SAPSS) and TCSC-based stabilizer (SACSC) design. The design problem is formulated as an optimization problem where SA is applied to search for the optimal setting of the proposed SAPSS and SACSC parameters. A pole placement-based objective function to shift the dominant eigenvalues to the left in the s-plane is considered. The proposed SAPSS and SACSC have been examined on a weakly connected power system with different disturbances, loading conditions, and system parameter variations. Eigenvalue analysis and nonlinear simulation results show the effectiveness and the robustness of the proposed stabilizers and their ability to provide efficient damping of low frequency oscillations. In addition, the performance ...

Science.gov (United States)

The macroscopic rotation of plasma in a toroidal containment device is an important feature of the equilibrium. Toroidal and polidal rotation in the high-beta tokamak Torus II is measured experimentally by examining the Doppler shift of the 4685.75 A He II line emitted from the plasma. The toroidal flow at an average velocity of 1.6 x 10/sup 6/ cm/sec, a small fraction of the ion thermal speed, moves in the same direction as the toroidal-plasma current. The poloidal flow follows the ion diamagnetic current direction, also at an average speed of 1.6 x 10/sup 6/ cm/sec. In view of certain ordering parameters, the toroidal flow is compared with predictions from neoclassical theory in the collisional, Pfirsch-Schluter regime. The poloidal motion, however, results from an E x B drift in a positive radial electric field, approaching a stable ambipolar state. This radial electric field is determined from theory by using the measured poloidal velocity. Mechanisms for the time evolution of ...

Energy Technology Data Exchange (ETDEWEB)

Neutron scattering experiments on the mixed-valence (MV) compounds SmB{sub 6} are reported. The inelastic magnetic response of SmB{sub 6} at T = 2 K, measured on a double-isotope single crystal,displays a strongly damped peak at 35 meV corresponding to the inter multiplet transition of Sm{sup 2+}. At lower energies ( h.{omega} {approx_equal} 14 meV), a narrow magnetic excitation is observed, with remarkable scattering-vector and temperature dependences of its intensity. This novel feature is discussed in terms of recent theoretical works describing the formation of an anisotropic local bound state in semiconducting MV materials. If the average samarium valence is decreased by substituting La for Sm, a peak is found to appear at high energies. The elastic magnetic form factor of SmB{sub 6} was determined using polarised neutrons and no significant difference is observed in its Q-dependence with respect to that of pure divalent samarium. This surprising behaviour is ...

International Nuclear Information System (INIS)

This work aims at improving the understanding of the dynamics of a Free Electron Laser (FEL) based on a storage ring. A new phenomenon of saturation by the electron bunch transverse dimensions is pointed out, during the FEL operation with a magnetic optics ''low emittance''. A part of this thesis work concerns the study of the longitudinal dynamics of the FEL depending on a parameter: the detuning between the pass frequency of the electrons and the back and return frequency of the laser pulse in the optical cavity. This study shows that the FEL presents a pulsed or a steady state behavior depending on the detuning. Besides, a spectro-temporal behavior of the FEL is pointed out showing the FEL pulse substructures and holes in the spectrum. Another part of this work concerns the response of the resonant FEL system, when a perturbation is applied on the gain. Under the effect of a modulation, the FEL can present a periodic or chaotic regime. The analysis of these regimes shows that a ...

International Nuclear Information System (INIS)

This paper presents a practical case study on the dynamic stability of the Saudi Electricity Company (SEC) power system and its effect on increasing power transfer limit of the interconnection between Eastern Operating Area (SEC-EOA). The problem of optimal tuning of the power system stabilizer parameters was converted into optimization problem wth eigenvalue-based objective functions, which was then solved by genetic algorithms. In this regard, two eigenvalue-based objective functions were considered and the problem is solved using real-coded genetic algorithm (RCGA). The effectiveness of the suggested technique to enhance the power system dynamic stability and to extend the power transfer capability limit of the SEC-EOA and the SEC-EOA power system was verified through a comprehensive eigenvalue analysis and time-domain nonlinear simulation. The results also indicated that the proposed tuning schemes of the existing stabilizers in the system have led to an improvement the system ...

CERN Document Server

A Langmuir film is a molecularly thin film on the surface of a fluid; we study the evolution of a Langmuir film with two co-existing fluid phases driven by an inter-phase line tension and damped by the viscous drag of the underlying subfluid. Experimentally, we study an 8CB Langmuir film via digitally-imaged Brewster Angle Microscopy (BAM) in a four-roll mill setup which applies a transient strain and images the response. When a compact domain is stretched by the imposed strain, it first assumes a bola shape with two tear-drop shaped reservoirs connected by a thin tether which then slowly relaxes to a circular domain which minimizes the interfacial energy of the system. We process the digital images of the experiment to extract the domain shapes. We then use one of these shapes as an initial condition for the numerical solution of a boundary-integral model of the underlying hydrodynamics and compare the subsequent images of the experiment to the numerical ...

Energy Technology Data Exchange (ETDEWEB)

A one-way coupling system between the plant simulator TRAC/BF1-ENTREE and the subchannel code with the improved cross flow model, NASCA, has been developed. Based on a scenario of turbine trip tests in the Peach Bottom Unit 2, the wide and rapid reactivity insertion transient induced by the system pressure rise was calculated. The pin power distribution in hot bundles was re-constructed considering heterogeneity of the fuel bundle. When the neighboring control blade is withdrawn, NASCA predicted that the steady-state bundle exit void distribution was nearly flat with regardless of the pin power distribution. However, void distributions in the middle and lower bundle regions became complicated depending on the pin power and the two-phase flow regime in each subchannel. The pin power distribution rapidly changed according to traveling of control blades. However, influence in the void distribution was delayed and damped due to the fuel heat conduction. The detailed ...

Energy Technology Data Exchange (ETDEWEB)

This work presents a digital adaptive Power System Stabilizer (PSS) which operates in a gain scheduling scheme. It`s parameters are designed for a lot of different operating regions in a P x Q plane (active and reactive powers), and saved in a microcomputer real time control. During working, the PSS identifies the present region of operation, and synthesizes its damping signal in accordance with the parameters for that region. As an extension of the method, a neural PSS, which uses the set of parameters of each region as a standard set to train a neural network to form this PSS, is also proposed. The tests presented show good performance for both PSS, when compared to a conventional (non adaptive) one. (author) 10 refs., 5 figs., 1 tab.; e-mail: jalb at guama.cpgee.ufpa.br

Energy Technology Data Exchange (ETDEWEB)

A stable, accurate, and efficient implementation of MacCormack's explicit algorithm for the Parabolized Navier-Stokes equations is demonstrated. The familiar problem of decoding the conservative axial flux vector is solved, resulting in accurate, smooth dependent variable profiles through the viscous-layer sonic line. Source terms due to transformation of the parabolized governing equations into the computational plane and the equations into the computational plane and the resulting metric differencing have been identified and eliminated through inclusion of appropriate geometric conservation law terms. Test cases computed include two- and three-dimensional supersonic and hypersonic flow at laminar and turbulent Reynolds numbers. The computed results demonstrate very good agreement with experiment and with solutions of the full Navier-Stokes equations. Computational times required for the MacCormack explicit PNS code are approximately equal to those of the existing implicit ...

CERN Document Server

Mobile entities with wireless links are able to form a mobile ad-hoc network. Such an infrastructureless network does not have to be administrated. However, self-organizing principles have to be applied to deal with upcoming problems, e.g. information dissemination. These kinds of problems are not easy to tackle, requiring complex algorithms. Moreover, the usefulness of pure ad-hoc networks is arguably limited. Hence, enthusiasm for mobile ad-hoc networks, which could eliminate the need for any fixed infrastructure, has been damped. The goal is to overcome the limitations of pure ad-hoc networks by augmenting them with instant Internet access, e.g. via integration of UMTS respectively GSM links. However, this raises multiple questions at the technical as well as the organizational level. Motivated by characteristics of small-world networks that describe an efficient network even without central or organized design, this paper proposes to combine mobile ad-hoc ...

Science.gov (United States)

Available from UMI in association with The British Library. Requires signed TDF. Design of time and correlation windows for non -parametric frequency response estimates. The thesis deals with problems that arise in the field of spectral analysis due to finite observations of input and output records. In particular, it is concerned with the method of applying time and correlation windows in spectral analysis procedures to obtain non-parametric frequency response estimates of open-loop time invariant systems. The thesis reviews and develops the sources of error that arise when frequency response techniques are applied directly to windowed records of input and output data to estimate the frequency response of open loop systems. Having identified the cause of these errors, methods of eliminating or reducing them are studied. The techniques introduced involve the use of differing time windows for the input and output data records. It is shown that windows can be designed on the basis of ...

UK PubMed Central (United Kingdom)

The rate of appearance of unlabelled glucose was calculated from tracer data and compared with the actual rate of infusion of unlabelled glucose into a anaesthetized dog with all sources of endogenous...Full Text Available

Science.gov (United States)

... Title : Wear Rate and Friction Coefficient in Liquid Nitrogen and Hydrogen of Steel Sliding on Polymer Laminates (Various Fabrics and Polymers. ...

British Library Electronic Table of Contents (United Kingdom)

This paper employs a new approach in order to investigate the underlying relationship between stock markets and exchange rates. Current approaches suggest that the relative equity market performance of two countries is linked to their exchange rate. In contrast, this study proposes an alternative approach where one global variable - global equity market returns - is believed to have an effect on exchange rates, with the relative interest rate level of a currency determining the sign of the relationship. Our empirical findings suggest that exchange rates and global stock market returns are strongly linked. The value of currencies with higher interest rates is positively related with global equity returns, whereas the value of currencies with lower interest rates is negatively related with g...

Energy Technology Data Exchange (ETDEWEB)

A simple heuristic calculation is given for the rate of nucleation of black holes at positive temperature. This calculation is based on the classical theory of nucleation and reproduces the result of Gross, Perry, and Yaffe.

Science.gov (United States)

... 129 US Armored Division Casualty and Tank Loss Rates ..... 132 British Casualty and rank Loss Rates in Operation "Goodwood" . 134 Page 5. ...

UK PubMed Central (United Kingdom)

Raffle, P. A. B. (1974).British Journal of Industrial Medicine,31, 152-158. Disability rates of bus drivers. The proposal that ordinary driving...Full Text Available

KoreaScience (Korea)

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Energy Technology Data Exchange (ETDEWEB)

No abstract prepared.

KoreaScience (Korea)

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DEFF Research Database (Denmark)

Udgivelsesdato: Dec

KoreaScience (Korea)

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International Nuclear Information System (INIS)

Short communication.

KoreaScience (Korea)

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PMID:11506019

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... dose rates inhalation iodine 134 krypton 88 nuclear decay quality factor

Energy Technology Data Exchange (ETDEWEB)

A dual-rate self-tuning control technique, in which the system identification and control calculation are performed separately, is proposed in this paper. This greatly increases the control rate. A self-tuning power system stabilizer (DSPSS) making use of this technique is developed and implemented using multi-micro-computers. Simulation and experimental results with DSPSS show that the increase in the control rate can considerably improve the system performance.

British Library Electronic Table of Contents (United Kingdom)

The chemostat theory on two species competition has shown that the dilution rate where transition of dominance occurs - transition-dilution rate - is independent of limiting-nutrient concentration. However, we obtained the experimental data indicating that the transition-dilution rate changed with variations in limiting-ammonium concentrations, using the chemostat mixed-culture of the cyanobacterium Microcystis novacekii and the green alga Scenedesmus quadricauda. The transition-dilution rate was dependent on the concentration of limiting ammonium in the influx culture medium. We tried to simulate the experimental results. Though the dilution rate has been considered independent of nutrient concentration, we introduce the effective dilution rate that depends on nutrient concentration (ammo...

Science.gov (United States)

The present study investigates the effect of the shear rate-dependent thermal conductivity of non-Newtonian fluids on the heat transfer enhancement in a pipe flow. The constant heat flux as thermal boundary condition was adopted in the thermally developed region. The present analytical results show the heat transfer enhancement over those of a shear rate-independent thermal conductivity fluid. The heat transfer coefficient ratio (h/h{sub 0}) linearly increase with the non-dimensional average velocity difference which is the product of the shear rate-dependence of the thermal conductivity and wall-shear rate.

Energy Technology Data Exchange (ETDEWEB)

The optimizing criterion is assumed to be the maximum net present value of the project. The following summarizes the significant conclusions. (1) Over a large range of discount rates, mining and milling of the mineral deposit at a constant cutoff grade and a constant production rate consistently results in smaller annual discounted cash flows than the optimal schedule determined by the dynamic programming model (dpm) where the cutoff grade and mining rate are allowed to vary in response to fluctuating product price. (2) With an increasing discount rate, under the dpm the annual discounted cash flows decrease at a slower rate than if the mineral inventory is mined and milled at a constant cutoff grade and a constant production rate. (3) Cuttoff grade increases only where higher equity ore is available. Thus, to maintain the mill feed requirement, the mining ...

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A variable-compression ratio, direct-injection diesel engine (VCR) has been designed and assembled at Southwest Research Institute with the intention of examining the current procedures for rating the ignition quality of diesel fuels and the meaning of ignition delay as an indicator of ignition and combustion quality. Using a slightly modified ASTM D 613 procedure, the engine has been used to rate the ignition quality of 43 different test fuels. The ratings obtained in the VCR engine are compared to the corresponding rating obtained using the standard cetane rating procedure. Some of the problems associated with the standard procedure became apparent during these experiments. The experimental results are discussed in terms of the problems and the advantages of a proposed VCR-based rating procedure.

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To evaluate the success rates, long-term patency rates and factors affecting the patency rates of percutaneous transluminal angioplasty(PTA) and thrombolysis in the management of insufficient access during hemodialysis. Between January 1991 and March 1995, 37 insufficient shunts(23 native fistulae and 14 graft fistulae) were treated in 31 patients. PTA was performed in 24 shunts, and thrombolysis in 13;in seven of these latter, thrombolysois was followed by PTA. The success and long-term patency rates of PTA and thrombolysis were evaluated. Shunts were subdivided according to a patient's age, type and age of the shunt, and number and length of the stenosis, and the degree of residual stenosis and in each subgroup, patency rates was compared. The overall success rate of PTA and thrombolysis for insufficient hemodialytic access was 78.4%(29/37). The ...

Science.gov (United States)

In our previous paper (Lanzafame et al. 2000, PASJ 52, 515) we showed, through 2D SPH simulations, that the stellar mass ratio, M 2 / M 1, of a close binary system (that determines the position and then the initial specific angular momentum at L 1) plays a fundamental role in the formation and development of spiral structures and shock fronts in the radial flow of accretion discs. In that work only a quasi-sonic value of the injection velocity at L 1 was considered. In the present work we also carried out 2D SPH simulations with the aim to investigate the development of such structures, while keeping constant the mass of the compact primary (M 1 = 1 M odot) and the separation between the two components, and assuming as an initial condition of two different supersonic injection velocities at L 1, characterizing two sets of simulations. For each set we considered four values of the secondary to primary mass ratio, M 2 / M 1. We worked out 2D models because the ...

International Nuclear Information System (INIS)

The paper describes the experimental and analytical results of the pipe whip tests performed under the PWR LOCA conditions using 4, 6 and 8 inch test pipes. The tests were carried out at an initial pressure and a temperature of 15.7 MPa and 325 "0C. Two different types of tests were performed. One was the cantilever type pipe whip test using the test pipe of 3000 mm in length and U-shaped restraints. The other was the cross-over leg pipe whip test using a 1/6 model of piping in the PWR nuclear power plants. The cantilever type pipe whip tests were performed to investigate the influences of overhang length and pipe diameter on the pipe whip behavior. The movement of the test pipe is limited effectively by the restraints when the overhang length is short. The restraint force increases in proportion to the breaking area. The cross-over leg pipe whip test was performed to demonstrate the integrity of the restraints at the LOCA. Strain-gages, accelerometers and load cells were used to ...

Science.gov (United States)

Abstract High-mobility group box 1 (HMGB1), a damage-associated molecular pattern (DAMP) molecules, favors tissue regeneration via recruitment and activation of leukocytes and stem cells. Here we demonstrate, in a model of acute sterile muscle injury, that regeneration is accompanied by active reactive oxygen species (ROS) production counterbalanced and overcome by the generation of antioxidant moieties. Mitochondria are initially responsible for ROS formation. However, they undergo rapid disruption with almost complete disappearance. Twenty-four hours after injury, we observed a strong induction of MURF1 and atrogin-1 ubiquitin ligases, key signals in activation of the proteasome system and induction of muscle atrophy. At later time points, ROS generation is maintained by nonmitochondrial sources. The antioxidant response occurs in both regenerating fibers and leukocytes that express high levels of free thiols and antioxidant enzymes, such as superoxide dismutase ...

Science.gov (United States)

Gas phase oxidation and catalytic oxidation of element mercury (Hg(0)) to bivalent mercury (Hg(2+)) were proposed to improve the mercury removal efficiency in the wet flue gas desulfurization (WFGD) system. However, the re-emission of Hg(0), generated by the reduction of absorbed Hg(2+), would lead to a damping of the total mercury removal efficiency. In this paper, the absorption and reduction behaviors of bivalent mercury in the Ca-based WFGD slurry were evaluated in our purpose-built device. According to our experimental results, the slurry chemistry (such as CaSO(3) content, SO(4)(2-), Cl(-) and pH value) had a strong influence on the reduction of absorbed bivalent mercury. And the inlet concentrations of SO(2) and O(2) contribute little to the mercury absorption. Within the typical pH value range of 4.5-5.5, about 70% of inlet bivalent mercury was converted to Hg(0). The re-emission of Hg would be greatly retarded with the increase of [SO(4)(2-)] due to the ...

Energy Technology Data Exchange (ETDEWEB)

Fully coupled, Newton-Krylov algorithms are investigated for solving strongly coupled, nonlinear systems of partial differential equations arising in the field of computational fluid dynamics. Primitive variable forms of the steady incompressible and compressible Navier-Stokes and energy equations that describe the flow of a laminar Newtonian fluid in two-dimensions are specifically considered. Numerical solutions are obtained by first integrating over discrete finite volumes that compose the computational mesh. The resulting system of nonlinear algebraic equations are linearized using Newton`s method. Preconditioned Krylov subspace based iterative algorithms then solve these linear systems on each Newton iteration. Selected Krylov algorithms include the Arnoldi-based Generalized Minimal RESidual (GMRES) algorithm, and the Lanczos-based Conjugate Gradients Squared (CGS), Bi-CGSTAB, and Transpose-Free Quasi-Minimal Residual (TFQMR) algorithms. Both Incomplete Lower-Upper (ILU) ...

UK PubMed Central (United Kingdom)

BackgroundExisting studies concerning the health care use of homeless people describe higher utilisation rates for hospital-based care and emergency care, and lower rates for primary...Full Text Available

UK PubMed Central (United Kingdom)

Sustained metabolic rates (SusMR) are time-averaged metabolic rates that are measured in free-ranging animals maintaining constant body mass over periods long enough that metabolism is fueled by food...Full Text Available

UK PubMed Central (United Kingdom)

We have measured the forward and reverse rates of the allosteric transition of hemoglobin A with three CO molecules bound by using modulated excitation coupled with fluorescence quenching of the DPG...Full Text Available

Science.gov (United States)

Results are reported from studies of the diffusion rate of xenon through frog abdominal skin and toad urinary bladders, typical epithelial membranes. It was concluded that intracellular water serves as the principal barrier for xenon passage through epithelial tissue.

UK PubMed Central (United Kingdom)

BackgroundControversy exists about how to effectively measure patient reported outcomes in IBS clinical trials. Pain numeric rating scales (NRS) are widely used in...Full Text Available

UK PubMed Central (United Kingdom)

Basal or standard metabolic rate (SMR) has been found to exhibit substantial intraspecific variation in a range of taxa, but the consequences of this variation are little understood. Here we explore...Full Text Available

Energy Technology Data Exchange (ETDEWEB)

In the region of annular liquid film-mist flow, the behavior of the droplets formed from the liquid film and the rate of formation are the subjects to be clarified in connection with the forecast of dry-out point, which becomes a problem in the region of high dryness such as reactor cooling system and steam generators. Many researches have been performed on such problem in vertical tubes, but the characteristics in horizontal flow have not yet been sufficiently clarified. This series of research is to clarify various characteristics, such as the velocity of vapor phase, the flow rate distribution of droplets, the formation and adhesion of droplets and the structure of liquid film, in the region of liquid film-mist flow, where liquid film exists on the bottom of a horizontal rectangular channel, and vapor flow is accompanied by droplets. In this study, by the measurement of the flow rate distribution of droplets on ...

UK PubMed Central (United Kingdom)

From the gross conservation laws of thermodynamics in a convecting material we derive a bound on the ratio of the rate of production of mechanical or magnetic energy to the rate of internal radioactive...Full Text Available

International Nuclear Information System (INIS)

Hoogenstraaten's heating rate method has generally been considered as a reliable method for determining thermoluminescence trapping parameters of first order glow peaks. However, experience has shown that in some cases the deviation between the heating rate method and glow curve fitting method can be quite significant (considering only the linear part of the heating rate plot, of course). In this study it is shown that one of the main reasons for this deviation can be a systematic increase of a temperature lag between the measured and real temperature of the sample with increasing heating rate. It appears that this systematic increase of the temperature lag affects the method in the range of low heating rates (linear part of the heating rates plots) more than has been previously realised. The effect of the temperature lag on Hoogenstraaten's heating ...

Energy Technology Data Exchange (ETDEWEB)

To evaluate the effectiveness of percutaneous transluminal angioplasty(PTA) and to determine the factors affecting the long-term patency rate in the management of insufficient hemodialytic arteriovenous fistula(AVF). Forty-nine cases of insufficient hemodialytic AVF were treated in 44 patients(native AVF:20, graft AVF:29, M:17, F:27, Age:22-70 years). In 28 thrombus patients, thrombolysis was performed with urokinase, and was followed by PTA. The initial success rate and complications of PTA were evaluated. According to the site and length of the stenosis, type and age of the AVF, the presence or abscence of thrombus, a history of diabetic mellitus, the patient's age, and the duration of renal failure, patency rates were compared within each subgroup using the Kaplan-Meier logrank test. The initial success rate of PTA for insufficient hemodialytic AVF was 88%(43/49), the patency ...

UK PubMed Central (United Kingdom)

Cimetidine 1 g daily is often continued for a fixed period beyond the time of healing of duodenal ulcer on the assumption that it might reduce the subsequent relapse rate. To test this, 194 patients...Full Text Available

UK PubMed Central (United Kingdom)

Energetically costly behaviours, such as flight, push physiological systems to their limits requiring metabolic rates (MR) that are highly elevated above the resting MR (RMR). Both RMR and MR during...Full Text Available

UK PubMed Central (United Kingdom)

For the evaluation of the kidney impairment, serum creatinine concentrations or glomerular filtration rates are mainly used, and the conditions of solitary or transplanted kidney and chronic dialysis...Full Text Available

Energy Technology Data Exchange (ETDEWEB)

This book contains over 20 selections. Some of the titles are: Continuum damage mechanics studies on the dynamic fracture of concrete; Dynamic compressive strength of cementitious materials; Rate-sensitivity of mode I and mode II fracture concrete; and An impact damage model of concrete.

Science.gov (United States)

The fuel cell model also provides the cryogenic use rates to the cryogenics model. The primary subroutines are FUELIV and. FUCLTM. ...

International Nuclear Information System (INIS)

When decontaminated with continuously replenished CAN-DECON reagent in a once-through system, carbon steel contaminated with "6"0Co during exposure to reducing coolant in stainless steel loops loses up to 90 percent of its radioactivity in the first few minutes. Afterwards, the rate of removal falls to much lower values which persist for many hours to the end of the experiment. The effects of flow rate, temperature and reagent concentration on the initial rates of decontamination indicate that mass transfer in the liquid is an important factor in the decontamination. The decontamination factor is influenced by the initial rate.

Energy Technology Data Exchange (ETDEWEB)

Effect of strain rate, temperature and grain size in the climb-controlled dislocation creep region for AZ31 magnesium alloy was examined at lower temperature of {proportional_to}473 K. The flow stress was not affected by the difference in grain size. The strain rate sensitivity, m, was obtained 0.14 and 0.2 at low temperatures in high strain rate and at high temperature in low strain rate, respectively. It was found that the notion of effective diffusivity could express the dominant diffusion process during climb-controlled dislocation creep behavior uniquely. (orig.)

KoreaScience (Korea)

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CERN Document Server

We briefly report on zero-temperature photoassociation of a Bose-Einstein condensate, focusing on the many-body rate limit for atom-molecule conversion. An upgraded model that explicitly includes spontaneous radiative decay leads to an unanticipated shift in the position of the photoassociation resonance, which affects whether the rate (constant) maximizes or saturates, as well as the limiting value itself. A simple analytical model agrees with numerical experiments, but only for high density. Finally, an explicit comparison with the two-body unitary limit, set by the size of the condensate, finds that the many-body rate limit is generally more strict.

Science.gov (United States)

The ionization, excitation, and radiative recombination rates for highly stripped ions are cal- culated with Maxwellian and non-Maxwellian electron distribution functions of the type Cmexp(-vm/wm) (2<=m<=5) as encountered in laser-heated plasmas and certain types of turbulent plasmas. The direct-radiative-recombination rates are found to decrease by at most 30% as m is increased from 2 to 5. On the other hand, the ionization and excitation rates are found to be strongly reduced if the transition energy ? exceeds twice the local temperature kBTe. The effect of this on the distribution of energy levels and degrees of ionization in laser-produced plasmas could be important.

Energy Technology Data Exchange (ETDEWEB)

Measurements of the expansion rate of pure-electron plasmas have been performed on the Electron Diffusion Gauge (EDG) device at background helium gas pressures in the 5 x 10(superscript -8) Torr to 1 x 10(superscript -5) Torr range, where plasma expansion due to electron-neutral collisions dominates over plasma expansion due to trap asymmetries. It is found that the expansion rate, defined as the time rate of change of the particles' mean-square radius, scales approximately linearly with pressure and inversely as the square of the magnetic field strength in this regime, in agreement with classical predictions.

International Nuclear Information System (INIS)

... Sciences, Research Center for Radiation Protection, Chiba (Japan) Hafez,

UK PubMed Central (United Kingdom)

To obtain the low birth weight (LBW) rate, the very low birth weight (VLBW) rate, and gestational age (GA)-specific birth weight distribution based on a large population in Korea, we collected and analyzed...Full Text Available

International Nuclear Information System (INIS)

The total radiation rate, angular distribution of the emitted energy and photon correlations of the cooperative spontaneous radiation from two atoms with different resonance frequencies and spontaneous decay rates are calculated. Contrary to the case of two identical atoms oscillations appear in the total radiation rate and the spatial distribution of the total number of emitted photons differs from the single-atom radiation pattern. The effect of the dipole-dipole near-field interaction on the time evolution of the atomic system is discussed. (author).

British Library Electronic Table of Contents (United Kingdom)

Intermittent sun exposure and sunburn are strong predictors of cutaneous malignant melanoma (CMM). On the other hand, melanomas may arise also in non-sun-exposed areas such as the vulva. However, little is known about a possible relationship between sun exposure and vulvar melanoma. Temporal and latitudinal dependencies of the incidence rates of vulvar melanoma were studied in comparison with those of CMM among Caucasians in Sweden, East Germany, USA and Victoria (Australia). The ratios of vulvar melanoma incidence rates to those of CMM tend to decrease with increasing CMM rates. The incidence rates of CMM have increased with time until recently, while those of vulvar melanoma have either decreased or remain constant. In USA vulvar melanoma incidence rates seem to increase from south to no...

Energy Technology Data Exchange (ETDEWEB)

The effects of the heating rate from 0.6 up to 50{sup o}C.s{sup -1} on the thermoluminescence of {alpha}-Al{sub 2}O{sub 3}:C are very intensive. The material rapidly loses its high sensitivity as the heating rate increases. The peak shape characteristics, peak maximum and full width at half maximum agree only qualitatively with those theoretically predicted. The trapping parameters calculated by the curve fitting method, the peak shape method, the variable heating rate method and the initial rise method, were found to decrease as the heating rate increases. The validity of the results are discussed in the framework of the kinetic models. (author).

British Library Electronic Table of Contents (United Kingdom)

Summary 1.-The metabolic theory of ecology (MTE) predicts that, after correcting for body mass variation among organisms, the rates of most biological processes will vary as a universal function of temperature. However, empirical support for -universal temperature dependence- (UTD) is currently equivocal and based on studies of a limited number of traits. 2.-In many ectothermic animals, the rate at which females produce mature eggs is temperature dependent and may be an important factor in determining the costs of reproduction. 3.-We tested whether the rate of egg maturation in marine turtles varies with environmental temperature as predicted by MTE, using the time separating successive clutches of individual females to estimate the rate at which eggs are formed. We also assessed the pheno...

International Nuclear Information System (INIS)

Turbulent premixed methane-air combustion in a cylindrical chamber is numerically simulated considering radiation effect. Reaction rates are considered as minimum rates between Arrhenius rates and eddy break up rates. A five step reduced mechanism is used. Turbulent modeling is done via standard k-? model imposed by empirical inlet boundary conditions. Source terms of energy equation consist of reaction rates and radiation effects. The discrete ordinate method (DOM) is employed to solve the radiative transfer equation (RTE) and the weighted sum of gray gas model (WSGGM) is imposed to consider radiation effect of non-gray gases. The results indicate that in the case of turbulent combusting flows, the effect of radiation of gases can affect the temperature and species concentrations. The numerical results obtained considering radiation effect are closer to the experimental data than ...

British Library Electronic Table of Contents (United Kingdom)

Introduction: The QT interval of the electrocardiogram (ECG) reflects the duration of ventricular depolarization and repolarization. A drug-induced prolongation of ventricular repolarization, and thereby QT prolongation, is recognized to be a marker for an enhanced risk for ventricular arrhythmia. The assessment of a drug's effect on the QT interval has therefore become routine within pharmaceutical research and development. However, the heart rate has a major influence on the QT interval; the QT interval shortens as heart rate increases such that one needs to account for such heart rate-dependent changes when evaluating possible drug-induced effects on the QT interval. The relationship between the QT interval and heart rate can be modeled mathematically and using this function a so-called...

International Nuclear Information System (INIS)

An Fe-15Cr-20Ni ternary model alloy and a Type 316 stainless steel were irradiated by dual-ions at 1 to 50 appm of He/dpa ratios, to investigate the helium effects on microstructural development in austenitic alloys under irradiation. Quantitative analysis on resultant microstructures revealed that the Frank loop nucleation rate and the network dislocation density positively correlate and Frank loop growth rate negatively correlate with the He/dpa ratio, while the cavity growth rate has its peak at an intermediate helium injection rate. Although He/dpa dependence of various microstructural features were similar for the model alloy and the 316SS, the rates of their development and the mechanism which had assisted cavity growth were significantly different in these two materials. (orig.).

International Nuclear Information System (INIS)

Purpose: To provide a feedwater control device capable of minimizing the adverse response of steam drum level at low power. Consitution: In order to perform feedwater control at low power by the substantial control of three factors, that is, main steam flow rate, feedwater flow rate and steam drum level, the main steam flow rate is determined from the reactor output and feedwater rate is determined from the changes in the feedwater temperature due to the mixing of waters in the reactor clean up system and feedwater. If a difference is resulted between these flow rates, a starting feedwater regulator is controlled instantly to eliminate the difference. The water level in the steam drum is used for amending the difference from the final set value of the drum water level, by which the adverse response of the steam drum level can be minimized. (Seki, T.).

Energy Technology Data Exchange (ETDEWEB)

Measurements of local mass fluxes of liquid, local number fluxes of the drop and local drop size distributions at various locations in the test column were made for wide ranges of liquid flow rates and gas flow rates. An empirical correlation for the volume mean diameter of the drop at the nozzle exit was proposed. Measurements of the rates of absorption of carbon dioxide from carbon dioxide-air mixtures with water sprays (physical absorption) and aqueous sodium hydroxide sprays (chemical absorption) were made for wide range so fluid flow rates, feed gas concentrations, and initial alkali concentrations. The observed dimensionless rates of absorption were compared with the theoretical values by assuming penetration model with second-order irreversible reaction. 11 refs., 7 figs.

Energy Technology Data Exchange (ETDEWEB)

A Vacuum Circuit Breaker demonstrated its ability to interrupt short circuits with faster than normal rates of rise of Transient Recovery Voltage (TRV) at levels greater than those produced by most transformer secondary faults. Two recent exploratory test programs evaluated the interrupting ability of a 15kV Vacuum Circuit Breaker containing interrupters of the rotating arc type with contacts made from a Chromium-Copper powder metal mixture. The interrupting conditions covered a wide range of currents from 10% to 130% of the 28kA rated short circuit current of the tested circuit breaker and a wide range of TRV rates of rise, including the relatively slow rate of rise, normally used in testing and found in most indoor circuit breaker applications; two faster rates of rise equaling and exceeding those found in a known power plant transformer secondary protection application; and the ...

International Nuclear Information System (INIS)

Object: To control the average liquid level of each steam generator at a constant level irrespective of the flow rate of sodium thereby to decrease change in the retained amount of sodium and at the same time to improve the load response characteristic. Construction: A method for decreasing to as large an extent as possible a change in the amount of sodium retained in a steam generator due to change in the flow rate, which comprises the steps of detecting the main recirculating flow rate of liquid sodium by the use of a sodium flow rate detector, amplifying the detected flow rate signal depending upon the ratio between the flow rates respectively in a super-heater and a re-heater (distribution ratio), delivering the amplified signal to a function generator which generates a liquid level setting signal for maintaining the respective average liquid levels of the ...

Energy Technology Data Exchange (ETDEWEB)

The Terra Nova offshore oil project is described, with emphasis on the construction of the Terra Nova Floating Production Storage and Offloading (FPSO) vessel, the first such vessel constructed for the harsh environment of the North Atlantic off Newfoundland, the site of an oil field that is expected to produce 125,000 to 150,000 barrels of oil per day starting in 2001. The vessel has a double-hull, made of 3,000 tons of reinforced steel to protect it from ice in the form of massive icebergs or crusty 'packs'. The vessel has the world's largest quick release turret, meaning that the vessel can be quickly disconnected from its turret and mooring in the event of an encroaching iceberg, and then reconnected in an environmentally sound way. Apart from its extremely rugged construction, protecting the FPSO vessel against icebergs is accomplished by way of 'hosing down' (by melting by powerful streams of water) or 'lassoing' (by ...

Energy Technology Data Exchange (ETDEWEB)

The Stockpile Stewardship Program (SSP) is a single, highly integrated technical program for maintaining the surety and reliability of the U.S. nuclear stockpile. The SSP uses past nuclear test data along with current and future non-nuclear test data, computational modeling and simulation, and experimental facilities to advance understanding of nuclear weapons. It includes stockpile surveillance, experimental research, development and engineering (D&E) programs, and an appropriately scaled production capability to support stockpile requirements. This integrated national program requires the continued use of current facilities and programs along with new experimental facilities and computational enhancements to support these programs. The Advanced Simulation and Computing Program (ASC) is a cornerstone of the SSP, providing simulation capabilities and computational resources to support the annual stockpile assessment and certification, to study advanced ...

Energy Technology Data Exchange (ETDEWEB)

One of the major achievements of the magnet R&D program for the Superconducting Super Collider (SSC) is the fabrication and test of a series of 20 5-cm aperture, 15-m long dipole magnet prototypes. The ramp rate sensitivity of these magnets appears to fall in at least two categories that can be correlated to the manufacturer and production batch of the strands used for the inner-coil cables. The first category, referred to as type-A, is characterized by a strong quench current degradation at high ramp rates, usually accompanied by large distortions of the multipole fields and large energy losses. The second category, referred to as type-B, is characterized by a sudden drop of quench current at low ramp rates, followed by a much milder degradation at larger rates. The multipole fields of the type-B magnets show little ramp-rate sensitivity, and the energy losses are smaller than ...

International Nuclear Information System (INIS)

Quantitative bone scintigraphy was performed in 24 patients with prostatic carcinoma before orchiectomy and up to one to four years after operation. The gamma camera count rate was recorded over the lower thoracic and all lumbar vertebrae 4 h after injection of "9"9"mTc-MDP. Twelve patients has normal bone scintigrams throughout the study. They showed from two years after operation a slight increase in count rate values compared with the preoperative values, probability due to hormonal changes after orchiectomy and to age-related alterations in skeletal metabolism. Twelve patients had abnormal bone scintigrams. They showed as a response to treatment the flare phenomenon with an increase in count rate over the abnormal vertebrae when measured two weeks after operation followed by a decrease after two months. The lowest count rate values were obtained between six months and one year after operation. ...

Energy Technology Data Exchange (ETDEWEB)

The scalar mixing time scale, a key quantity in many turbulent combustion models, is investigated for reactive scalars in premixed combustion. Direct numerical simulations (DNS) of three-dimensional, turbulent Bunsen flames with reduced methane-air chemistry have been analyzed in the thin reaction zones regime. Previous conclusions from single step chemistry DNS studies are confirmed regarding the role of dilatation and turbulence-chemistry interactions on the progress variable dissipation rate. Compared to the progress variable, the mixing rates of intermediate species is found to be several times greater. The variation of species mixing rates are explained with reference to the structure of one-dimensional premixed laminar flames. According to this analysis, mixing rates are governed by the strong gradients which are imposed by flamelet structures at high Damkoehler numbers. This suggests a modeling ...

Energy Technology Data Exchange (ETDEWEB)

Estimates of annual rates of change of fuel switching are constructed using logistic curve models fitted to often sparse historical data on fuel use in the USA. The estimated annual rate of loss of market share of an old fuel is then shown to be correlated with five-year averages of declines in the rate of growth of affected vehicle numbers. Other statistical tests show a positive correlation between five-year average changes in the rate of growth of the vehicle numbers and of macroeconomic activity when the affected vehicles are directly responsible for a large share of that activity. The vehicle types shown to have this effect are locomotives from 1885-1915 and automobiles thereafter. The third set of tests supports an interpretation that the indirect effects of fuel switches are significant and consistent with GNP throughout the 1880-1980 period. It is shown that a pronounced drop in GNP growth ...

International Nuclear Information System (INIS)

A series of experimental measurements of the yield of O_3 in nuclear-induced O_2 and O_2-SF_6 discharges are reported. The discharges were created by bombardment with energetic particles from the "1"0B(n,#alpha#)"7Li reaction. Continuous irradiation at dose rates of 10"1"5--10"1"7 eV cm"-"3 s"-"1 and pulsed irradiation (--10 ms FWHM) at a peak dose rate of --10"2"0 eV cm"-"3 s"-"1 were conducted. At the lower dose rates, the addition of SF_6 generally increased the ozone yield due to the slowing of ozone destruction by negative oxygen and ozone ions. In contrast, at the high dose rates, the ozone concentration decreased due to SF_6 suppression of atomic oxygen formation by ion--ion recombination. A numerical model was developed and tested against experimental conditions. This model indicates that the steady-state ozone concentration was limited by the reaction O"-_3+O_3#->#2O_2+O"-_2 with a ...

Science.gov (United States)

Maintenance energy expenditures were mesured for five rumen bacteria, Selenomonas ruminantium, Butyrivibrio fibrisolvens, Bacteroides ruminicola, Megasphaera elsdenii, and Streptococcus bovis, by using a complex medium with glucose as the carbon source. Large differences (as high as 8.5-fold) in maintenance energy expenditures were seen among these bacteria. The suggestion is made that maintenance requirements could be a significant determinant of bacterial competition in the rumen. Theoretical maximum growth yields, calculated from double reciprocal plots of yield versus dilution rate, were compared to theoretical Y(ATP) values in order to estimate minimum molar adenosine 5'-triphosphate yields from glucose for each bacterium. Results showed that relative yield among the bacteria was growth rate dependent. At high dilution rates, both S. ruminantium and S. bovis produced lactate as their principal fermentation product. At ...

Energy Technology Data Exchange (ETDEWEB)

The two-phase annular regime is characterized by a high velocity gas stream flowing through the core of the tube surrounded by a thin, highly agitated liquid film flowing concurrently along the tube wall. Part of the liquid may be entrained as droplets in the gas phase. The specific goals of this study were to measure fully developed rates of interchange and entrained fraction over a wide range of flow variables in the upward configuration of the annular regime, to obtain a more fundamental understanding of liquid interchange phenomena via studies of liquid film characteristics and to develop an improved design correlation for the entrained fraction. Towards this end, air-water experiments were conducted in two vertical pipe lines, 2.54 and 4.20 cm in diameter. Air velocities ranging from 20 to 120 m/s and total liquid flow rates ranging from 10 to 100 g/s were investigated. Two models for the rate of atomization, proposed ...

International Nuclear Information System (INIS)

An optical klystron is built in the 800 MeV electron storage ring at University of Science and Technology of China for harmonic super-radiation generation. In single bunch operation mode the repetition rate of the spontaneous radiation pulses is about 4.533 MHz, and the repetition rate of the seed laser pulses is about 3 Hz, while the radiation pulse duration is 300 ps. For measuring harmonic radiation a high on/off ratio ICCD is used as an optical switch to reject spontaneous radiation pulses of high repetition rate

British Library Electronic Table of Contents (United Kingdom)

The effect of particle/matrix interface debonding on composites consisting of elastic particles and viscoelastic matrix is studied. The interface debonding is represented by a nonlinear cohesive law for the high explosive PBX 9501. The Mori-Tanaka method gives the constitutive relation of the composite in terms of the properties of elastic particles, viscoelastic matrix, and nonlinear cohesive law for interfaces. For the example of a composite with spherical particles subject to hydrostatic tension, simple analytical expressions of the composite stress-strain relation are obtained. The strain rate and temperature have strong effects on the composite behavior. High strain rate and low temperature give high strength of the composite. However, the rate and temperature effects decrease as the ...

CERN Document Server

Convexity/concavity properties of symbol error rates (SER) of the maximum likelihood detector operating in the AWGN channel (non-fading and fading) are studied. Generic conditions are identified under which the SER is a convex/concave function of the SNR. Universal bounds for the SER 1st and 2nd derivatives are obtained, which hold for arbitrary constellations and are tight for some of them. Applications of the results are discussed, which include optimum power allocation in spatial multiplexing systems, optimum power/time sharing to decrease or increase (jamming problem) error rate, and implication for fading channels.

International Nuclear Information System (INIS)

Standard radiation monitoring has been conducted at Sendai nuclear power station for the purpose of estimation of 'source activity' during refueling outage and evaluation of countermeasures to reduce dose rate. Selected objects of the monitoring are radiation dose rate at maintenance area, radiation field at each equipment and piping, coolant chemistry and plant operation condition. Monitored data indicates that 'source activity' variation can be estimated to some extent using influential factors, and that evaluation of change of loose crud activity, which is presumed to be represented by the dose rate at letdown heat exchanger, is necessary to further explain change in radiation field at main work area. (author).

Energy Technology Data Exchange (ETDEWEB)

Study of the rate of dissolution in simulated lung fluid of uranium from 3 different ore matrices and from refined uranium dioxide in an essentially all teflon extraction apparatus; the rate of dissolution of thorium from a nickel metal/2 percent thoria mixture; the effect of neutron irradiation of the studied materials upon the dissolution rates; and the adsorptions of the radioisotope tracers barium 133 (substitute for radium), lead 203 and thorium 234 upon the extraction system components.

British Library Electronic Table of Contents (United Kingdom)

In this article we obtain an alternative formulation of the von Mises type conditions for p-max stable laws in terms of generalized log Pareto distributions (glogPds). Relationship between the rate of convergence of extremes and the remainder terms in the von Mises type conditions is investigated. It is shown that the rate of convergence in the von Mises type conditions for p-max stable laws determines the distance of the underlying distribution function from a glogPd.

International Nuclear Information System (INIS)

Experimental differential cross sections for 104 MeV #alpha#-particle scattering have been analysed using a method recently proposed for model-independent analyses. Reliable values of isoscalar (0"+ -3"1"-) octupole transition rates in _5_0Ti, _5_2Cr and _2_0_8Pb are presented and compared with electromagnetic rates. (author).

Energy Technology Data Exchange (ETDEWEB)

Absolute fission rate measurements using modified National Bureau of Standards fission chambers were performed in the Fast Flux Test Facility at two core locations for isotopic deposits of {sup 232}Th, {sup 233}U, {sup 235}U, {sup 238}U, {sup 237}Np, {sup 239}Pu, {sup 240}Pu, and {sup 241}Pu. Monitor chamber results at a third location were analyzed to support other experiments involving passive dosimeter fission rate determinations.

International Nuclear Information System (INIS)

With the help of heat balance equation and high temperature thermodynamic function, the calibration relation of jet temperature with discharge power, gas flow rate was obtained for nitrogen thermal plasma. It was shown that the results were agreed with the principle of similarity. The jet temperature was a function of Peff/f, instead of a general two variables function of Peff and f, which were effective discharge power and working gas flow rate, respectively. A related discussion has been given; it will be referable to thermal plasma applications. (authors)

Environmental Research Database

DescriptionRates of ice accumulation in Antarctica are not known well, yet they are fundamental to assessing the ice sheet mass balance. Past accumulation rates are less well defined. We are in a unique position to provide detailed accounts of accumulation in Antarctica. We will measure isochronous internal layering across the ice sheet, which can be readily identified in radar data that we hold. Internal layers will be traced to ice-cores (allowing dating) and across wide regions of the ice sheets. A nume [continued...

International Nuclear Information System (INIS)

Monte Carlo criticality calculations have been performed for over 50 years for reactor physics and criticality safety applications. With today's faster computers, these calculations are being carried out to greater precision (smaller uncertainties) in keff, and detailed distributions of power and reaction rates are being computed routinely. This paper provides a review of the fundamental theory of Monte Carlo criticality calculations, with guidance on practical methods for: (1) assuring convergence of both keff and the source distribution, (2) minimizing the bias in keff and reaction rate distributions, and (3) dealing with the under-prediction bias in uncertainties for keff and reaction rate distributions. (authors)

UK PubMed Central (United Kingdom)

BackgroundLate-onset sepsis in the premature infant is frequently revealed by severe, unusual and recurrent bradycardias. In view of the high morbidity and mortality...Full Text Available

CERN Document Server

We study the temporal evolution of coronal loops using data from the Solar X-ray Imager (SXI) on board of GOES-12. This instrument allows us to follow in detail the full lifetime of coronal loops. The observed light curves suggest three somewhat distinct evolutionary phases: rise, main, and decay. The durations and characteristic timescales of these phases are much longer than a cooling time and indicate that the loop-averaged heating rate increases slowly, reaches a maintenance level, and then decreases slowly. This suggests that a single heating mechanism operates for the entire lifetime of the loop. For monolithic loops, the loop-averaged heating rate is the intrinsic energy release rate of the heating mechanism. For loops that are bundles of impulsively heated strands, it is an indication of the frequency of occurrence of individual heating events, or nanoflares. We show that the timescale of the loop-averaged heating ...

UK PubMed Central (United Kingdom)

The development of both the mammalian oocyte and the somatic cell compartments of the ovarian follicle is highly coordinated; this coordination ensures that the ovulated oocyte is ready to undergo fertilization...Full Text Available

Science.gov (United States)

... PERSONAL AUTHOR(S) ROY A. BROOKS, LTC i3a. ... gave the impression of an immediate increase in the standard ... high rate by German standards. ...

Science.gov (United States)

... Figure 3a. PETN Filled Tube Specimen Detonated by Exploding Bridgewire Specimen POLYETIILLENE END-CAP "1- 901am WALL IHICKNESS ...

Science.gov (United States)

... f(i, k, α) if node k is the terminal node for ... under which the mean service rate at queue (i, k ... occur frequently in studies of stability in stochastic networks ...

Energy Technology Data Exchange (ETDEWEB)

Titanium oxides were grown anodically to selected final potentials on grade II polycrystalline titanium under different anodization rates. XPS and RBS results show that the oxide consists of primarily TiO2 with a non-stoichiometric oxide/metal interface, with the slower growth rate associated with a thicker layer at the interface. Characterization using TEM reveals that the structure of the oxide evolves from a primarily amorphous phase to islands of crystallites in an amorphous matrix, to an entirely crystalline phase by increasing the polarization potential. Slower growth rates tend to remain crystalline at higher potentials. The mechanical strength of oxide films extracted from load-depth data by nanoindentation varies dramatically for oxide films grown by different rates at 9.4 V, and to a lesser extent at lower potentials. The variation of film strength is associated with both compositional and ...

UK PubMed Central (United Kingdom)

Concentrations of ammonia and the chlorine stabilizer, cyanuric acid, which could be expected in swimming pools decreased the rate of kill by chlorine of the potential pathogen, Pseudomonas...Full Text Available

UK PubMed Central (United Kingdom)

ObjectiveTo assess whether 17 alpha-hydroxyprogesterone caproate reduces the rate of preterm birth in women carrying triplets.MethodsFull Text Available

Science.gov (United States)

An experimental study of H-air counterflow diffusion flames (CFDFs) is reported. Coaxial tubular

Science.gov (United States)

Aluminum electrolytic capacitors are presently not allowed ..... specified for commercial aluminum electrolytic capacitors of similar rating. ...

Wastenet

...Systems, UWA investigating rate uplift effects of shallow foundation systems associated with high voltage transmission line support towers. This work was funded by National Grid, ...

Science.gov (United States)

Metastable yttrium-oxide films are synthesized using reactive sputter deposition. The yttrium concentration of the as-deposited film is found to vary as a function of the sputter deposition rate. In addition to the synthesis of the cubic equilibrium phase...

Science.gov (United States)

[[pdf] Reference Guide for Proposals 07/09 [pdf] FY11 Overhead Rate Calculator (xls) DARPA Opportunities NIH Proposals (Leads & Subcontractors) [NIH Office] Related Links MST...

UK PubMed Central (United Kingdom)

At present time, there is evidence from randomized controlled studies of the success of laparoscopic resection for the treatment of colon cancer with reported smaller incisions, lower morbidity rate...Full Text Available

Science.gov (United States)

Jun 6, 2011 ... Sick leave is earned at a rate of 4 hours per pay period. ... The Federal Employees Retirement System (FERS) is a three-tiered pension plan ...

Energy Technology Data Exchange (ETDEWEB)

A new test methodology is described which allows access to loading rates that lie between split Hopkinson bar and shock-loading techniques. Gas gun experiments combined with velocity interferometry techniques have been used to experimentally determine the intermediate strain-rate loading behavior of Coors AD995 alumina and Cercom silicon-carbide rods. Graded-density materials have been used as impactors; thereby eliminating the tension states generated by the radial stress components during the loading phase. Results of these experiments demonstrate that the time-dependent stress pulse generated during impact allows an efficient transition from the initial uniaxial strain loading to a uniaxial stress state as the stress pulse propagates through the rod. This allows access to intermediate loading rates over 5 x 10{sup 3}/s to a few times 10{sup 4}/s.