Partial Dissipation Research Articles

Bubble control in gas-fluidized beds with applied electric fields

In some gas-fluidized bed applications the presence of bubbles and channeling is undesirable due to gas bypassing. The partial or total dissipation of such bubbles will contribute to improved fluidized bed performance in applications, such as combustion and catalytic reactors, where intimate gas—particle contact is important. Preliminary studies in this laboratory over the past two years demonstrate that, in laboratory size gas-fluidized beds, bubbles can be controlled in size and intensity by the application of suitably applied electric fields. The electric fields are shown to be effective at a gas—solid particulate interface and therefore “seek out” any existing bubbles within the bed. The required electric fields are of the order kV/cm in strength and are found to be influential on a variety of particulate materials including both good conductors ( e.g. copper) and semi-insulators ( e.g. coal, glass, limestone). Both a.c. and d.c. electric fields, applied with and without electrode—particle contact, are discussed on two bed geometries: rectangular and cylindrical. Data are presented for the case of a.c. electric fields with the electrodes placed externally to the bed. In a separate experiment, data collected on various kinds of particles by “gravity lifting tests” suggest that larger particles (and beds) than those fluidized here (29 – 390 μm) can also be so controlled.

The 35 m superconducting cable test facility

To demonstrate the technical feasibility and capability of superconducting ac cables a 35 m long ac single phase test cable for 110 kV and 10 kA is under construction at present. The rigid cryogenic envelope has already been assembled. Good experience was gained with the applied mounting technique which is described. Wires consisting of a high purity Al-core enclosed by a thin layer of Nb are used as cable conductors. They were fabricated in lengths of several thousand meters under large scale conditions and exhibited excellent electrical behaviour. After manufacturing some dummies with pure Al-wires, a 50 m long originally sized flexible cable core consisting of superconducting wires and wrapped HDPE tape insulation was fabricated on conventional cable machinery in our cable works. Dielectric measurements at 4.2 K and 2.5 bar on originally sized and large scale fabricated cable core pieces yielded breakdown voltages, partial discharge inception voltages and dissipation factors which are compatible with cable standards. Two one phase 110 kV - 10 kA cable terminations have been constructed and tested. They showed satisfying behaviour with respect to stress and current loads.

Effect of long-chain fatty acids and acyl-CoA on mitochondrial permeability, transport, and energy-coupling processes.

The following effects of fatty acids and acyl-CoA thioesters on energy metabolism of mitochondria can now be assumed: (1) Inhibition of adenine nucleotide translocation. This effect may increase the energy state of mitochondria respiring under state 3 conditions and decrease phosphorylation potential in the surrounding medium (the cytoplasm). (2) Increased permeability to monovalent cations. This may lead to a partial energy dissipation due to a futile recycling of K+ (or another cation), namely and energy-dependent uptake and a passive outflow. (3) True uncoupling due to increased permeability to protons. This effect probably occurs at high concentrations of fatty acids only. (4) Substrate effect. Fatty acids in the form of acyl-CoA are excellent respiratory substrates for mitochondria of most tissues. Their oxidation is coupled to the generation of high energy state of the mitochondrial membrane and, consequently, to ATP synthesis.

Integration of the equations of motion of nonholonomic systems with a partial dissipation of energy

Integration of the equations of motion of nonholonomic systems with a partial dissipation of energy

On equilibrium instability for conservative and partially dissipative systems

The investigation brings some contributions to the classical problem of inverting the Lagrange-Dirichlet stability theorem. First, an example is given of a conservative holonomic mechanical system with a stable equilibrium at the origin, although the potential function is strictly negative along some rays issuing from the origin. Then, one establishes a new instability result in the conservative case. Last, by means of a vector auxiliary function, one proves an instability theorem for holonomic systems with partial dissipation.

Failure of vasopressin to prevent the natruiretic and diuretic response to unilateral stimulation of carotid baroreceptors.

Unanesthetized rats treated with deoxycorticosterone acetate were continuously infused with a maximally effective dose of vasopressin (50 muU/min per 100 g). After a control period of 2 h the animals were subjected to a 2 h period of unilateral stimulation of the carotid baroreceptors. There was a large natriuretic response accompanied by diuresis and a fall in urine osmolality. It was concluded that neither the natriuretic nor the diuretic response could be explained by inhibition of vasopressin secretion. Analysis of kidney tissue indicated that the diuresis was associated with partial dissipation of the inner medullary concentration gradient.

Membrane-mediated killing of Saccharomyces cerevisiae by glycoproteins from Torulopsis glabrata

Cell-free supernatants from cultures of Torulopsis glabrata contained glycoprotein toxins that killed sensitive and killer strains of Saccharomyces cerevisiae with single-hit kinetics. Growing S. cerevisiae treated with the toxins showed a leakage of cellular potassium, partial dissipation of the adenosine triphosphate pool, and a coordinate shutdown of macromolecular synthesis. These pool efflux-stimulating toxins have been partially purified and at least three toxic glycoproteins have been separated. Pool efflux-stimulating toxin activity was stable from pH 3 through 7, though killing was maximal close to pH 4.

The effect of the phenolic antibacterial agent fentichlor on energy coupling in Staphylococcus aureus.

Summary. Experimental evidence indicates that inhibition of active transport is responsible for the bacteriostatic action of Fentichlor against Staphylococcus aureus. Fentichlor inhibits active transport and assimilation of glutamic acid, and assimilation of glucose under aerobic and anaerobic conditions, but inhibition of assimilation results mainly from inhibition of accumulation rather than direct action on the assimilation process. In the absence of glucose, Fentichlor dissipates the membrane proton gradient and ATP pool but, with glucose present, ATP synthesis is unaffected and although some acceleration of proton translocation occurs, only partial dissipation of the gradient results. Results indicate that Fentichlor‐mediated proton translocation prevents coupling of membrane proton movements to active transport as postulated by the chemiosmotic hypothesis. Fentichlor partially inhibits glycolysis and anaerobic ATP synthesis which may contribute to bacteriostasis under anaerobic conditions.

Stability analysis of dynamic systems with couplings and integrals of motions: PMM vol. 38, n≗4, 1974, pp. 607–615

We give a method for obtaining the stability conditions for nonlinear systems, based on an analysis of the linearized coupling equations and of the linearized or quadratic expressions for the integrals of motion. Liapunov's method is usually employed in the investigation of the stability of dynamic systems. The investigation of the Hamiltonian function is a convenient tool for systems with internal energy dissipation. In fact, in the development of the Thompson (Lord Kelvin)-Tait-Chetaev theorem [1–4] it was shown that the positive definiteness of the Hamiltonian function provides the necessary and sufficient stability conditions in the case of complete dissipation. We have obtained just sufficient conditions for system with partial dissipation; moreover, the method does not yield the possibility of obtaining far-reaching inferences on stability on the basis of the analysis of the linearized equations. It should be noted also that in several cases it is convenient to introduce a number of variables, exceeding the number of degrees of freedom, and to examine the couplings. Then the equations can be simplified or represented in a form convenient for stability analysis.

Adaptation of mouse leukemic cells (L5178Y) to anisotonic media: I. Cell volume regulation

Mouse lymphoma cells (L5178Y) exposed to hypertonic media for 1 h behave as osmometers, but in hypotonic media, after initial swelling, they shrink back to normal volume and maintain it for long periods of time. The lower limit of osmolarity at which this “volume adaptation” will occur lies between 140 and 185 mosM. The “volume adaptation” is associated with a loss of cellular K + probably due to a transient increase in K + permeability and to loss of associated anions and osmotically obliged water. Partial dissipation of the large gradient of K + between cells and medium by pre-exposure to ouabain or to K +-free medium results in a diminished capacity to adapt. After the shrinking phase is completed, a new steady state is established with a reduced cellular K + content, normal Na +, normal K +-permeability, and a reduced activity of the Na + − K + transport system. When adapted cells are returned to normal medium, an initial shrinking is followed by a re-swelling to normal size, associated with a gain in K + content, presumably due to the return to normal activity of the Na + − K + transport system.

On equilibrium instability in holonomic mechanical systems with partial dissipation: PMM vol. 37, n≗4, 1973, pp. 640–646

We prove a theorem on the instability of the equilibrium of a dissipative system in the absence of a maximum of the force function. The dissipation is partial and is absent only in one of the degrees of freedom. The proof is based not on the linearization of the differential equations but on Liapunov's direct method and uses a somewhat modified form of Krasovskii's theorem. The instability is established for systems with arbitrary nonlinear dissipative forces and an isolated equilibrium.

On the stabilization of relative equilibrium and steady-state motion of a mechanical system by partial dissipation forces: PMM vol. 36, n≗ 4, 1972, pp. 589–597

On the stabilization of relative equilibrium and steady-state motion of a mechanical system by partial dissipation forces: PMM vol. 36, n≗ 4, 1972, pp. 589–597

Photometric Observations of V1057 Cygni

view Abstract Citations (21) References (9) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Photometric Observations of V1057 Cygni Mendoza V., Eugenio E. Abstract UB VI?' photometry and total absorptions of neutral-oxygen lines at 7774 were obtained for V1057 Cyg. These observations show a high luminosity for this object and give more evidence to affirm that the brightening of V1O57 Cyg is a manifestation of the same event that caused the brightening of FU Ori. The infrared excess can be interpreted as the presence of a chcumstellar dust cloud; however, the change in spectral type from K to A indicates that an intrinsic change took place, in addition to a partial dissipation of the circumstellar dust cloud. Publication: The Astrophysical Journal Pub Date: November 1971 DOI: 10.1086/180824 Bibcode: 1971ApJ...169L.117M full text sources ADS | data products SIMBAD (4) Related Materials (1) Erratum: 1972ApJ...172L..77M

Wake-temperature turbulent fluctuation decay rates deduced from O sub 2 radiation.

The effects of temperature fluctuations in a hypersonic turbulent wake on a chemical reaction with a strong temperature dependence are analyzed to determine the appropriate turbulence parameters for several different turbulent wake models. The chemical reaction selected for its temperature sensitivity is the atomic-oxygen chemiluminescent recombination. This radiation has been measured behind nonablating spheres in air in the General Motors Ballistic Range by Reis. The wake turbulence models are: a) random inviscid convection (so-called marble cake), b) homogeneous mixing, c) partial dissipation or bimodal model, d) mixinglag models, and e) gaussian mean-temperature profile with superimposed fluctuations. The data are interpreted in terms of each model. It is shown that models a, b, and d are inconsistent with the data. The radiation is interpreted in terms of the unmixed volume fraction of the partial dissipation model to obtain the rms turbulent temperature and mass density fluctuations and the turbulent dissipation function, which is then applied to predict the rms fluctuations of electron density. It is found that the resulting predictions are consistent with other measurements. The dissipation function indicates that the mixing-lag length is equal to about 20 wake radii. The model involving the Gaussian mean-temperature profile and fluctuations is consistent with the data for a thermal half width equal to slightly less than ha]f the mean turbulent front wake radius, with the temperature fluctuation ratio on the axis between 0.3 and 0.5. This is consistent with the measured mean-temperature profiles and temperature fluctuations, but the results are very sensitive to the mean temperature in the wake.

Asymptotic stability of the equilibria of gyroscopic systems with partial dissipation: PMM vol. 32, no. 2, 1968, pp. 314–318

Asymptotic stability of the equilibria of gyroscopic systems with partial dissipation: PMM vol. 32, no. 2, 1968, pp. 314–318

Counter Displacement in the Visual Figural After-effect

In this study an attempt is made to specify the conditions under which counter displacement (test contour displaced toward the inspection contour) will occur. Three experiments are described in which different lengths of inspection of the test-(T-) figure are given following short and long inspections of the inspection-(I-) figure. In Experiment I, after partial dissipation of the figural after-effect (FAE), a period of continuous inspection of the T-figure was employed. In Experiments II and III distributed inspection of the T-figure was given by increasing the number of measurements of the FAE. In all experiments counter displacement was evident. The results were consistent with an interpretation of counter displacement offered earlier by the authors.

Characteristic damping exponents for vibrations of mechanical systems with partial dissipation

Characteristic damping exponents for vibrations of mechanical systems with partial dissipation

On asymptotic stability of equilibria and stationary motions of mechanical systems with partial dissipation

On asymptotic stability of equilibria and stationary motions of mechanical systems with partial dissipation

THE KINETICS OF PENETRATION

When cells of Halicystis are impaled on a capillary so that space is provided into which the sap can migrate, the rate of entrance of water and of electrolyte is increased about 10-fold. In impaled Valonia cells the rate is increased about 15-fold. After a relatively rapid non-linear rate of increase of sap volume immediately after impalement (which may possibly represent the partial dissipation of the difference of the osmotic energy between intact and impaled cells) the volume increases at a linear rate, apparently indefinitely. Since the halide concentration of the sap at the end of the experiment is (within the limits of natural variation) the same as in the intact cell, we conclude that electrolyte also enters the sap about 10 times as fast as in the intact cell. As in the case of Valonia we conclude that there is a mechanism whereby in the intact cell the osmotic concentration of the sap is prevented from greatly exceeding that of the sea water. This may be associated with the state of hydration of the non-aqueous protoplasmic surfaces.

The Measurement of X-rays with Liquid Ionization Chambers

TWO years ago, we reported2 some preliminary measurements on the ionization produced in liquid carbon disulphide by x-rays. Our interest in the problem lies in its possible application to medical dosage in cases in which we wish to measure the total number of ions produced in tissue-equivalent material. While it is impossible to attain saturation conditions in liquids, as is common with gases, we have shown that the saturation current may be deduced by plotting the reciprocal of the current against the reciprocal of the applied voltage, V, and extrapolating linearly to 1/V = 0. For high fields the plot is nearly linear in accord with Jaffé's theory of columnar ionization (1, 2). However, when a steady direct current potential is applied to a liquid ionization chamber, a barrier potential arising from a space charge or surface layer is built up, which quickly reduces the field in the liquid to roughly 45 per cent of the applied value. This barrier potential reaches an appreciable value in a small fraction of a second but does not attain its maximum magnitude for about ten minutes, during which interval the measured ionization current decreases exponentially. Figure 1 shows the measured ionization current, as a function of the lapse of time for a succession of different potentials applied to the plates of the ionization chamber—with and without x-radiation. It is seen that for each increase in voltage, with x-rays on, the ionization current rises to a high value, then falls off, rapidly at first, to an essentially steady value in about ten minutes. As indicated, this is caused by the building up within the cell of a barrier potential. If, on the other hand, the applied potential be decreased, the ionization current drops abruptly to a low value, then gradually rises again to a considerably higher steady value in about the same ten-minute period. This second sequence results from the partial dissipation of the barrier potential set up by the higher applied voltage and consequently increases the field strength within the liquid. Finally, if the applied potential be removed and the circuit closed, the ionization chamber becomes itself a transient source of current. It is interesting to note, also, how the space charge depends upon other factors associated with the use of a liquid ionization chamber. In Figure 2 the barrier potential is plotted against the potential actually applied to the plates of the chamber. Curves A show that, without x-rays, the barrier potential is proportional to—about 45 per cent of—the applied potential. That is, the barrier potential, in the steady state, makes the field strength within the liquid about half that to be expected from the applied voltage. Curves B show that for a definite applied voltage, the barrier potential decreases with increase in the intensity of the x-rays producing the ionization. Contrary, perhaps, to expectations, this decrease in barrier potential is due to the increased conductivity of the liquid which permits a more rapid dissipation of the space charge.