Function Of Pumping Rate Research Articles

The plant for obtaining an aqueous radon solution

Developing indicator methods to determine the main characteristics of cores extracted from oil-bearing strata presupposes simple, radiation-safe installations of an aqueous radon solution. This study describes such an installation, comprising crushed uranium ores weighing ~45 kg. Herein, we investigated the radon concentration (RC) of water as a function of pumping rate and duration to determine the optimal pumping conditions necessary for achieving a maximum RC in water of ~3 kBq/L.

Impact of luminescence quenching on relaxation-oscillation frequency in solid-state lasers

Measurement of the laser relaxation-oscillation frequency as a function of pump rate allows one to determine parameters of the laser medium or cavity. We show that luminescence quenching of a fraction of the rare-earth ions in a solid-state laser affects the relaxation oscillations, resulting in incorrect values for the parameter deduced from this measurement. In the equations describing the relaxation oscillations, we replace the lifetime of the upper laser level by an effective lifetime that takes the luminescence quenching into account. In an Al2O3:Yb3+ distributed-feedback laser we observe significant quenching, with the effective lifetime being ∼18 times shorter than the intrinsic upper-laser-level lifetime.

On the geochemistry of gases and noble gas isotopes (including 222Rn) in deep crustal fluids: the 4000 m KTB‐pilot hole fluid production test 2002–03

AbstractThe concentrations of H2, O2, CO2, and concentrations and isotopic composition of the noble gases (including 222Rn), N2, CH4, and higher hydrocarbons dissolved in 4000 m deep‐seated fluids from a 12‐month fluid production test in the KTB pilot hole were analyzed. This determination of the gas geochemistry during the test in combination with the knowledge of the hydraulic data provides relevant information about the fluid hydraulics of the deep system. All gas concentrations and isotopic signatures, except for 222Rn, showed constancy during the course of the test. This, in combination with large fluid flow rates at a moderate water table drawdown, imply an almost infinite fluid reservoir in 4000 m depth. From the change in 222Rn‐activity as a function of pump rate, the contribution of smaller and wider pores to the overall fluid flow in an aquifer can be deduced. This 222Rn‐activity monitoring proved therefore to be a valuable instrument for the qualitative observation of the scavenging of pore and fracture surfaces, a hydraulic feature invisible to standard hydraulic testing tools. The observance of this scavenging effect is due to (i) the continuous on‐line geochemical monitoring, (ii) the durability of the test, (iii) a change in pump rate during the course of the test, and (iv) due to the short half‐life of 222Rn. The fluids have a 5.9% mantle He component, and a δ21Ne excess of 14%, and a noble gas model age of about (5.5–6.2) ± 2.0 Myr. The mean N2/Ar‐ratio of 516 and δ15N‐data of about +1.5‰ indicates sedimentary or metamorphic origin of N2. The hydrocarbons, amounting to 33 vol.% in the gas phase, are derived from thermal decomposition of marine organic matter of low maturity. But a key question, the identification of the potential source region of the fluids and the migration pathway, is still unidentified.

Laser with thresholdless intensity fluctuations

We have studied the quantum-noise properties of a small slow-inversion laser experimentally and theoretically. As a function of pump rate, the average output intensity shows a sharp threshold, but the intensity fluctuations do not. Under quite generic conditions the intensity fluctuations of a sufficiently small slow-inversion laser show highly super-Poissonian statistics (even two times above threshold), due to the very weak damping of the spontaneous-emission-driven relaxation oscillation.

Presence of Nonconvexity in Groundwater Concentration Response Functions

This study examines the presence of nonconvexity and multiple extrema in the feasible region defined by the concentration response function. The response function is defined in the context of concentration constraints imposed on groundwater quality management models and is constructed assuming that concentration constraints are imposed at every node in a numerical grid. The groundwater system is represented by a homogeneous numerical simulation model. The response function is graphically depicted as a function of pumping rates at two wells. The dependence of the response function on simulation model and management model characteristics is examined by varying dimensionless parameter values. This study shows that the response surface is nonconvex and contains multiple local extrema over a wide range of parameter values. These features of the surface are most prominent at the transitions from extraction to injection pumping, Binding constraints often occur at or near low-velocity zones.

Efflux of photosynthate and acid from developing seed coats ofPhaseolus vulgarisL.: a chemiosmotic analysis of pump-driven efflux

Seed coats of Phaseolus vulgaris L. unload photosynthetic products, mineral ions and acid into the apoplastic space surrounding the embryo. We report measurements, on detached seed coats, of the rates of unloading of photosynthates, ions and acid at different external pH and in the presence of treatments intended to alter the rate of proton pumping. We also report measurements of membrane potential difference (PD) and of cytoplasmic pH under the same conditions, measurements which have allowed us to validate the treatments we used and to investigate functional relationships between membrane processes. A chemiosmotic model of the seed-coat cell membrane is proposed, in which sucrose efflux and acid efflux are both driven by the proton pump. Sucrose efflux is proposed to occur by sucrose/proton antiport driven by the proton-motive force (PMF), and acid efflux to occur by pumped protons accompanied by a passive efflux of anions. We use our measurements to estimate the net efflux of sucrose on the antiporter and the total efflux of protons on the pump. We have tested the model by using experimental treatments designed to manipulate the pump rate as the independent variable. Under these conditions, and assuming the model is correct, the pump rate determines the cytoplasmic pH. Over the range covered by our experiments the net sucrose efflux is dependent on external and cytoplasmic pH, the latter having the major role. The efflux of acid, under the same treatments, depends primarily on the proton pump rate, and was found to be well fitted by a quadratic function of pump rate. This means that, as pump rate increases, an increasing proportion of the pump output is used by acid efflux and a decreasing proportion by sucrose antiport. The membrane PD, although an important component of the PMF, does not appear to function in rate control of net sucrose or of acid efflux, since neither efflux is correlated with membrane PD under our treatments which vary the pump rate. The PD correlates well with external potassium concentration, and seems largely determined by the diffusion of potassium ions and anions.

Long-pulse, electron beam pumped, atomic xenon laser

Characteristics of a long-pulse, low pump rate, atomic xenon (XeI) laser are described. Energy loading up to 170 J/L at pulse widths between 5 and 55 ms is achieved with an electron beam in transverse geometry. The fraction of energy in each wavelength obtained with electron beam pumping is in good agreement with results from fission fragment pumping in a reactor pumped laser. Values for the small-signal gain coefficient, loss coefficient, and saturation intensity as a function of pump rate are presented. Laser energy as a function of pulse width and the effects of air and CO2 impurities are described. An investigation of the dominant laser wavelength in a high-Q cavity indicates that the 2.6 μm radiation dominates.

A simple kinetic model for electron-beam-pumped KrF lasers

A kinetic model for KrF is presented that, by neglecting all but the most important kinetic processes, adequately describes the performance of electron-beam-pumped KrF lasers by a few, simple analytical expressions. The expression for the saturation intensity as a function of pump rate and gas composition is checked by measurements of gain saturation in both argon-rich and krypton-rich laser mixtures. The effects of fluorine burn-up are considered and are shown to impose a fundamental relationship between output fluence and efficiency of KrF laser amplifiers.

A model-based system for assessing ventricular chamber pressure-volume-dimension relationship: regional and global deformation.

A system has been developed for measuring and relating in a non-beating isolated canine left ventricle dynamic changes in chamber pressure, volume, diameter, regional segment length, and wall thickness. The measurement system consists of a pulsatile blood pump whose stroke-volume and frequency can be adjusted selectively. The external pump system is used as a primary means for controlling instantaneous intraventricular volume. The relationship between left ventricular volume change, intraventricular pressure, minor axis diameter, and regional dimensions were studied as a function of pump rate. In addition to the basic constitutive properties, this system provided the means for measuring and comparing regional and global pressure-strain relationship including the effect of strain rate and its relationship to viscoelastic myocardial muscle model. The dynamic relationship between global dimensions and regional dimensions, circumferential segment length, and wall thickness were also investigated. The instantaneous relationship between intraventricular pressure resulting from periodic oscillations of chamber volume, including minor equator diameter, wall thickness, and regional segment dimensions were plotted and fitted to an exponential pressure-strain model, assuming a quasi-static large deformation. The observed difference between global and regional pressure-dimension strain stiffness coefficients can be attributed in part to basic constitutive and geometric considerations and not necessarily to the complex anisotropic or heterogeneous nature of cardiac muscle properties. This methodology provides indices which appropriately characterize the regional and global left ventricular chamber deformation and stiffness.

Gain measurements in the KrCl excimer laser

The single-pass/double-pass amplified spontaneous emission technique has been used to measure the net gain at 222.4 nm in a discharge-pumped UV-preionized KrCl laser. The net gain has been measured as a function of pump rate and total pressure in He- and Ne-based gas mixtures. A maximum net gain of 0.15 cm(-1) has been obtained in a 0.09% HC1/10.1% Kr/1.5% He/88.3% Ne mixture at a total pressure of 355 kPa and at a specific power loading of approximately 21 MW/cc. The data presented are compared with previous net gain measurements performed using the passive absorption cell method.

Absorption and gain measurements in the KrF laser medium at high pump rate

Losses have been measured at 257.2 nm in e-beam-pumped, KrF laser mixtures at pump rates up to 4 MW/cm3 and pressures up to 3000 Torr. A maximum absorption of 3.5% cm−1 is observed in a gas mixture of 4-Torr F2, 125-Torr Kr, and 2871-Torr Ar. Losses are reduced in the presence of lasing. The absorption cross section of Kr2F* at 257.2 nm is estimated to be 1.8(±1.1)×10−17 cm2. Net gain has been measured as a function of pump rate in a gas mixture of 4-Torr F2, 125-Torr Kr, and 1371-Torr Ar. A net gain of 22% cm−1 and a gain to nonsaturable loss ratio ∼20 have been observed.

Numerical Modelling of Pulsed Electric CO2 Lasers

A simple four-level kinetics model is combined with a cavity intensity model to predict the output pulse characteristics of pulsed electric discharge CO2 lasers for pressures ranging from 0.1 to 10 atm. Both free-running (gain-switched) and Q-switched cases are studied. Particular emphasis is placed on peak intensity and energy content of the initial spike as a function of pumping rate, gain at time of Q swithcing, mixture, and pressure.

Study of Multi-Wavelength Oscillations in an H2O Laser by Rate Equations

The far-infrared laser oscillations in water vapor is described theoretically in the form of rate equations in which the molecular rotation-vibration interaction of either Fermi or Coriolis type is taken into account. The theory is developed for the case of pulsed operation of relatively long duration on the assumption that the rotational relaxation time is much shorter than the duration of the excitation pulse. Theoretical expressions for (1) the output power in the steady state as a function of pumping rate and (2) the start-oscillation condition are given. The effects of multi-wavelength oscillations are also obtained and compared with experimental results.

Dependences of Output Powers on the Discharge Current in Single-Line and Two-Line Oscillations of He-Ne Lasers

A general method of expressing the output powers of gaseous lasers on a single line or simultaneous oscillations on two lines as a function of pumping rates and transition probabilities is developed from the standpoint of an electronic network analog of the rate equations. By application of this method to the 1.15 µ, 6328 Å, and 3.39 µ lines of He-Ne lasers, the dependences of their powers on the discharge current are discussed and found to be in agreement with experimental results. Furthermore, example of simultaneous oscillations of the 1.15 µ and 6328 Å lines as well as those of the 6328 Å and 3.39 µ lines are treated, giving results which are also in agreement with experimental results. Features of the dependences of the output powers on the discharge current in the simultaneous oscillations are stated in connection with those in the single-line oscillations.

Laser efficiency at high pump levels

A simple model for a laser oscillator has been analysed to determine the single mode efficiency for steady state operation at high pumping levels. The analysis takes into account the possibility of changes in the shape of the electromagnetic mode as the pumping rate is increased. Normalised plots of laser efficiency as a function of pumping rate and laser length indicate that changes in mode shape are important at moderate pump levels.