scholarly journals Experimental investigation of a line plume in a filling box

2020 ◽  
Vol 20 (6) ◽  
pp. 1579-1601
Author(s):  
Romana Akhter ◽  
Nigel B. Kaye
Keyword(s):  
Gravity Current ◽  
The Other ◽  
Box Model ◽  
Cube Root ◽  
Outflow Velocity ◽  
Entrainment Coefficient ◽  
Series Of Experiments ◽  
End Wall ◽  
Asymmetric Configuration ◽  
Front Movement

Abstract A series of experiments were conducted to quantify the dynamics of a filling box driven by a line plume that spans the full width of the enclosure. Three configurations were tested namely symmetric (centrally located plume), wall-bounded (plume attached to an end wall), and asymmetric. The front movement for the symmetric and wall-bounded configurations was well described by the standard filling box model. The front movement results indicate that the typical value of the entrainment coefficient $$ \left( \alpha \right) $$ α for an unconfined plume ($$ \alpha = 0.16 $$ α = 0.16 ) could be used to accurately predict the front movement for both the centrally located plume and the wall-attached plume. This is in contrast to other studies that suggest that wall-bounded plumes have a significantly lower entrainment coefficient. The standard filling box model broke down for the asymmetric configuration. As the plume was closer to one wall than the other, the plume outflows that spread out and reflected off the end walls returned to the plume at different times. This created a pressure imbalance across the plume that caused the plume to bend sharply toward the nearest wall. Analysis of the plume outflow as a constant flux gravity current showed that the outflow velocity scaled on the cube root of the plume buoyancy flux per unit width $$ f $$ f , a result confirmed by further experiments. This result was used to quantify the time at which the plume bends and the standard filling box model breaks down.

scholarly journals VIII. On the descending degenerations which follow lesions of the gyrus marginalis and gyrus fornicatus in monkeys

1889 ◽  
Vol 180 ◽  
pp. 331-354
Keyword(s):  
The Other ◽  
Post Mortem ◽  
Cerebral Lesions ◽  
Series Of Experiments ◽  
The Government ◽  
Government Grant

The following paper contains the record of an investigation into the degenerations which follow lesions of the gyrus marginalis and gyrus fornicatus in Monkeys. The work has been carried on under my direction by Mr. France, with the aid of a grant from the Government Grant Fund, and represents part of a long investigation into the degenerations which follow artificially produced cerebral lesions, the material for which has been furnished by cases operated upon in conjunction respectively with Professor V. Horsley and Dr. Sanger Brown. These cases and the physiological results of the operations have already been published in the ‘Philosophical Transactions.’ The experiments here dealt with, twelve in number, comprise only the lesions of the gyrus marginalis and gyrus fornicatus, and, with one exception (case 12), are taken from the series of experiments performed in conjunction with Mr. Horsley. Of the twelve cases, six were of removal, or attempted removal, of the gyrus marginalis, and six of removal, or attempted removal, of the gyrus fornicatus. But in only one or two instances was the lesion, as determined by post-mortem examination, exactly limited to the convolution which it was attempted to remove, for in most cases the adjacent gyrus was to a certain extent involved in the injury. This was especially the case when removal of the gyrus fornicatus had been attempted, on account of its deep situation, and the difficulty of getting at it without some manipulation of the superjacent gyrus. Nevertheless, the removal of one or the other gyrus was sufficiently complete in all the cases here selected to produce characteristic symptoms and characteristic descending degenerations.

scholarly journals XXI. On the construction of a new calorimeter for determining the radiating powers of surfaces in air; and its application to the surfaces of various mineral substances

1860 ◽  
Vol 150 ◽  
pp. 379-408
Keyword(s):  
Surrounding Medium ◽  
The Other ◽  
Absolute Amount ◽  
Present Communication ◽  
Atmospheric Air ◽  
Glass Bulb ◽  
Heated Body ◽  
Series Of Experiments ◽  
Quantity Of Heat ◽  
Limited Induction

When my paper on the Conductivity of various Substances was presented to the Society, it was intimated to me on the part of the Council of the Society, that it might be advisable to determine absolute instead of relative conductivities, the latter being alone attempted in my previous experiments. It has been partly in consequence of this intimation, as well as from the desire to make my investigations the more complete, that I have given my attention to the construction of a calorimeter which might serve for this purpose. The present communication contains a description of this instrument, with the results which it has enabled me to obtain respecting the absolute quantities of heat which emanate from the surfaces of certain substances under given conditions. 1. When a body is placed in atmospheric air (or any gas), the quantity of heat which is lost from its surface in a given time, when its temperature is higher than that of the surrounding medium, will be greater than if it were placed in a vacuum, other conditions remaining unaltered. In the latter case the heat escapes by simple radiation; in the other case a portion of the heat also escapes in consequence of the contact of the air with the surface of the heated body. Dulong and Petit ascertained by a careful series of experiments, the laws according to which the mercury contained in the bulb of a thermometer cools, or those which govern the quantity of heat which escapes from the surface of the containing bulb, when placed in a vacuum, in air, or in several kinds of gases. These experiments were made with the glass bulb naked, and also when it was silvered, so that the laws of radiation which they established were strictly in reference only to surfaces of glass and those of silver. Certain laws were identical in both these cases, and hence it was concluded, though by a limited induction, that the same laws were applicable to all other surfaces. They did not, however, give the absolute quantity of heat which, under given circumstances, and in a given time, emanates from the surfaces of the glass or silver with which they experimented. The instrument which I have constructed gives very easily this absolute amount of heat, as I believe, with very approximate accuracy.

Specification of retinotectal connexions during development of the toad Xenopus laevis

Development ◽  
1980 ◽  
Vol 55 (1) ◽  
pp. 77-92
Author(s):  
S. C. Sharma ◽  
J. G. Hollyfield
Keyword(s):  
Xenopus Laevis ◽  
Ganglion Cell ◽  
Retinal Ganglion Cells ◽  
Optic Tectum ◽  
Ganglion Cells ◽  
The Other ◽  
Retinal Ganglion ◽  
Visual Projection ◽  
Series Of Experiments ◽  
The Right

The specification of central connexions of retinal ganglion cells was studied in Xenopus laevis. In one series of experiments, the right eye primordium was rotated 180° at embryonic stages 24–32. In the other series, the left eye was transplanted into the right orbit, and vice versa, with either 0° or 180° rotation. After metamorphosis the visual projections from the operated eye to the contralateral optic tectum were mapped electrophysiologically and compared with the normal retinotectal map. In all cases the visual projection map was rotated through the same angle as was indicated by the position of the choroidal fissure. The left eye exchanged into the right orbit retained its original axes and projected to the contralateral tectum. These results suggest that retinal ganglion cell connexions are specified before stage 24.

Inertial gravity currents produced by fluid drainage from an edge

2017 ◽  
Vol 827 ◽  
pp. 640-663 ◽  
Author(s):  
Mostafa Momen ◽  
Zhong Zheng ◽  
Elie Bou-Zeid ◽  
Howard A. Stone
Keyword(s):  
Differential Equations ◽  
Gravity Current ◽  
Experimental Studies ◽  
Dynamical Behaviour ◽  
Rectangular Domain ◽  
Dimensionless Time ◽  
Horizontal Length ◽  
High Reynolds ◽  
End Wall ◽  
Similar Phase

We present theoretical, numerical and experimental studies of the release of a finite volume of fluid instantaneously from an edge of a rectangular domain for high Reynolds number flows. For the cases we considered, the results indicate that approximately half of the initial volume exits during an early adjustment period. Then, the inertial gravity current reaches a self-similar phase during which approximately 40 % of its volume drains and its height decreases as $\unicode[STIX]{x1D70F}^{-2}$, where $\unicode[STIX]{x1D70F}$ is a dimensionless time that is derived with the typical gravity wave speed and the horizontal length of the domain. Based on scaling arguments, we reduce the shallow-water partial differential equations into two nonlinear ordinary differential equations (representing the continuity and momentum equations), which are solved analytically by imposing a zero velocity boundary condition at the closed end wall and a critical Froude number condition at the open edge. The solutions are in good agreement with the performed experiments and direct numerical simulations for various geometries, densities and viscosities. This study provides new insights into the dynamical behaviour of a fluid draining from an edge in the inertial regime. The solutions may be useful for environmental, geophysical and engineering applications such as open channel flows, ventilations and dam-break problems.

I. On the volumetric relations of ozone and the action of the electrical discharge on oxygen and other gases

1860 ◽  
Vol 10 ◽  
pp. 427-428 ◽  
Keyword(s):  
Electrical Discharge ◽  
The Other ◽  
Pure Oxygen ◽  
Silent Discharge ◽  
Gaseous Substance ◽  
Series Of Experiments ◽  
The One

This paper contains the full details of the authors’ experiments on the volumetric changes which occur in the formation of ozone. From three distinct series of experiments, performed by different methods, they show that when ozone is formed from pure oxygen by the action of the electrical discharge, a condensation takes place, as had already been announced in a former Note published in the 'Proceedings.’ But the condensation is much greater than the earlier experiments of the authors on the expansion by heat of electrolytic ozone had indicated. It is, in fact, so great, that if the allotropic view of the constitution of ozone be correct, the density of that body, as compared with oxygen, would be represented by a number corresponding to the density of a solid or liquid rather than that of a gaseous substance. This conclusion follows necessarily from the authors’ experiments, unless it be assumed that when ozone comes into contact with such substances as iodine, or a solution of iodide of potassium, one portion of it is changed back into common oxygen, while the remainder enters into combination, and that these portions are so related to one another, that the expansion due to the one is exactly equal to the contraction arising from the other. For the details of the experiments and of the methods of investigation employed, reference must be made to the original paper. The second part of the communication is devoted to the action of the silent discharge and of the electrical spark on other gases. Hydrogen and nitrogen undergo no change of volume when exposed to the action of either form of discharge. Cyanogen is readily decomposed by the spark, but presents so great a resistance to the passage of electricity, that the action of the silent discharge can scarcely be observed. Protoxide of nitrogen is readily attacked by both forms of discharge, with increase of volume and formation of nitrogen and hyponitric acid. Deutoxide of nitrogen exhibits the remarkable example of a gas which, under the action either of the silent discharge or of the spark, undergoes, like oxygen, a diminution of volume. It also is resolved into nitrogen and hyponitric acid. Carbonic oxide has given results of great interest; but the nature of the reaction has been only partially investigated. The silent discharge decomposes this gas with production of a substance of a bronze colour on the positive wire. The spark acts differently, destroying, as in the case of oxygen, the greater part of the contraction produced by the silent discharge. The authors are engaged in the further prosecution of this inquiry.

The Effect of Sand/Cement Ratio and Cement Grade on the Compressive Strength of Foam Concrete

2013 ◽  
Vol 405-408 ◽  
pp. 2933-2937
Author(s):  
Ji Chuan Geng ◽  
Kun Ni ◽  
Shan Qi Fang ◽  
Yun Xing Shi ◽  
Yi Ning Ding ◽  
...  
Keyword(s):  
Compressive Strength ◽  
The Other ◽  
Foam Concrete ◽  
Cement Ratio ◽  
Series Of Experiments

A series of experiments have been undertaken to investigate the effects, on compressive strength, of variable sand/cement ratios and cement grade. Ten mixtures of different s/c ratios used two kinds of cement were cast and the compressive strength at different curing ages was tested. The results indicate that the compressive strength gets lower as the s/c ratio increases for both 42.5R and 32.5R cement. For the mixtures used 32.5R cement, the 28-day compressive strength is pretty low for the s/c ratios of 1.5 and 2. The specimens used 42.5R cement have higher compressive strength than those with 32.5R cement. The compressive strength decreases from 42.5R to 32.5R cement are significantly smaller for the s/c ratios of 0.5 and 1 than the other three s/c ratios.

scholarly journals Phytoremediation as a Prospective Method for Rehabilitation of Areas Contaminated by Long-Term Sewage Sludge Storage: The Greek Experience

2017 ◽  
pp. 836-853
Author(s):  
N. Suchkova ◽  
E. Darakas ◽  
J. Ganoulis ◽  
Y. Vergeles
Keyword(s):  
Sewage Sludge ◽  
Plant Species ◽  
Shoot Growth ◽  
The Other ◽  
Control Treatment ◽  
Distilled Water ◽  
Series Of Experiments ◽  
And Control ◽  
Control Samples

In this work the suitability of several plant species for phytoremediation under natural and artificially installed conditions was studied. Brassica napus, Medicago sativa, Zea mays, Triticum aestivum, and Hordeum vulgare were grown in pots with sewage sludge from Sindos Main WWTP in Thessaloniki and from Sindos Industrial WWTP in Thessaloniki, Greece. The first series of experiments included comparing measurements of various parameters for the above mentioned plants and the sludge to those for control samples (the same plants growing in compost). It was shown that shoot growth was less reduced in T. aestivum and H. vulgare than in the other plant species studied. B. napus had lower germination tax, followed by M. sativa with the lowest germination tax. Generally B. napus, giving less biomass production than Z. mays and T. aestivum, is characterised by a higher ability to accumulate heavy metals like Cd, Cu, Ni, Pb, Zn, Cr, As and Hg. The second series of experiments included comparing measurements of various parameters of B. napus grown in sludge and treated each 7 days with metal solutions of Ni, Zn and Pb containing 10-2mg/l, 10-4mg/l, 10-6mg/l of each metal, to those for control plants treated with double distilled water. Results showed that shoot growth of B. napus were increased at treatments with lower concentrations of metals (10-6 mg/l) and control (treatment with d-distilled water). At the same time uptake of metal ions was increased with the concentration of the solution, i.e. at higher concentrations (10-2 mg/l). It is truly for Pb and Zn, transfer coefficient TC of which (indicates a plant’s potential to concentrate a metal) was quite high 15 % and 7 % correspondingly. It was noticed that B. napus has high ability to accumulate Cr, from the other hand it did not accumulate Ni (at present case).

Effects of load and duration of tension on pain induced by muscular contraction

1962 ◽  
Vol 203 (4) ◽  
pp. 735-738 ◽  
Author(s):  
Syuk Ryun Park ◽  
Simon Rodbard
Keyword(s):  
Severe Pain ◽  
Total Duration ◽  
Muscular Contraction ◽  
The Other ◽  
Cube Root ◽  
Similar Relationship ◽  
Moderate Pain ◽  
Slight Pain ◽  
Mercury Column ◽  
Local Accumulation

Pain was induced in the ischemic forearm in more than 300 tests in seven subjects by an exercise which consisted of compression of an air bulb to raise or maintain a mercury column at 50, 100, or 200 mm for periods of 1, 2, 4, or 5.5 sec. The rate of pain development could be correlated with the product ( P) of the number of contractions, square root of the load (in mm Hg), and cube root of the duration of contraction (in sec). Slight pain appeared at a product of about 345 P, moderate pain at approximately 433 P, severe pain at 536 P, and intolerable pain at 626 P. A similar relationship could be shown in maintained contraction provided the total duration was treated as if each 5.5 sec of the maintained contraction constituted a separate contraction. Ischemia of the arm for periods up to 15 min had no effect on product. Recovery from the effect of exercise was complete in 10 min. Simultaneous exercise of the other arm had no effect on the rate of pain development. The results support the concept that muscle pain results from the local accumulation of a slowly diffusible material released during muscle contraction.

Rectal tone, distensibility, and perception: reproducibility and response to different distensions

1998 ◽  
Vol 274 (3) ◽  
pp. G584-G590 ◽  
Author(s):  
H. F. Hammer ◽  
S. F. Phillips ◽  
M. Camilleri ◽  
R. B. Hanson
Keyword(s):  
The Other ◽  
Rectal Distension ◽  
Abdominal Symptoms ◽  
Temporal Features ◽  
Balloon Distension ◽  
Basal Tone ◽  
Experimental Approaches ◽  
Series Of Experiments ◽  
Healthy Persons

Increasing interest is focusing on the role of intestinal tone, distensibility, and mechanosensation in the genesis of abdominal symptoms. Experimental approaches usually feature balloon distension of the bowel with measurements of perception, tone, and compliance and/or elastance; however, the methodologies are standardized incompletely. We examined the reproducibility of repeated assessments of sensory perception, basal tone, and compliance and/or elastance of the rectum during distension. We also evaluated the response to inflations that varied in regard to control of pressure or volume, pattern of distension, and rate of inflation. Five healthy volunteers were studied under two separate protocols. The first featured a series of experiments on each of 5 days; the other consisted of 2 separate days of study. Repeated distensions evoked reproducible responses of sensation and compliance and/or elastance on a single day, providing a conditioning distension preceded them. Day-to-day variability was also sufficiently small to allow valid comparisons to be made on different days in healthy persons. The configuration of the distension profile (phasic, staircase, or ramp) and the rate of inflation (from 1 to 40 ml/s) had little effect on distensibility or perception. Perceptions were sometimes transient and sometimes constant, but no relationship was found between these temporal features and the magnitude of the stimulus. These observations help provide a basis as to how the responses to rectal distension can be best studied.

A Study of Vulcanization Accelerators. I. Compounds Which React Analogously to Rubber

1957 ◽  
Vol 30 (3) ◽  
pp. 952-961
Author(s):  
J. Shimozato ◽  
K. Ura
Keyword(s):  
Zinc Oxide ◽  
Zinc Sulfide ◽  
Hydrogen Abstraction ◽  
Reaction System ◽  
Detailed Examination ◽  
The Other ◽  
Chemical Behavior ◽  
Model Compounds ◽  
Rapid Decomposition ◽  
Series Of Experiments

Abstract 1. To elucidate the chemical behavior of rubber toward sulfur, a series of experiments was carried out using model compounds : tetralin, toluene, xylene, aniline, phenol, chlorobenzene, dichlorobenzene and naphthalene. Similar reactivities between rubber and the model compounds were observed. 2. The effects of the accelerators in the reactions of the model compounds with sulfur were different according to whether or not zinc oxide was present in the reaction system. 3. A detailed examination of the quantities of zinc sulfide formed in the reaction of tetralin with sulfur in the presence of zinc oxide showed that several vulcanization accelerators have similar activating effects in rubber vulcanization. 4. With tetralin as reactant, the quantity of zinc sulfide decreased suddenly at the reaction temperature 150° C, which was ascribed to the rapid decomposition of tetralin peroxide at this temperature. 5. The accelerating action of CPB, contrary to that of the other accelerators, was promoted by tetralin peroxide. 6. Tetralin peroxide had only a small inhibiting influence upon reactions with the amine accelerators, which is ascribed to the antioxidative nature of the amine derivatives; the inhibiting influence becomes larger in reactions with thiol derivatives or without any added accelerators. 7. Substituent effect on the hydrogen abstraction of the model compounds was primarily determined by the negativity of the relevant carbon atom. The order of the reactivity was found to be in accord with that toward the general “cationoid reagents”. 8. Analytical methods during and after the reactions were simplified for industry use.

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