Tubes Of Various Diameters Research Articles

Elastic wave propagation in bone in vivo: Methodology

The purpose of this study was to investigate the usefulness of elastic wave propagation (EWP) in estimating the mechanical properties (elasticity) of human tibia. The test group was composed of 78-yr-old women assigned to high ( n = 19) and low ( n = 17) bone mineral density (BMD) groups as measured at the calcaneus by the 125I-photon absorption method. The EWP apparatus consisted of an impact-producing hammer with a force strain gauge and two accelerometers positioned on the bone. Results for nylon and acrylic were used to calibrate the apparatus. Polyvinyl chloride (PVC) solid rods and tubes of various diameters were used to evaluate the relationship between the elastic wave velocity and cross-sectional area. The density and the cross-sectional area of tibia were measured by the computerized tomographic (CT) method at the same intersection points as velocity recordings. The velocities in tibia of bending waves produced by the mechanical hammer were found to depend on the density, area moment of inertia, and density-dependent elastic constants of bone. It is important to account for the changes of these quantities along the bone. It is suggested that the velocity of elastic waves and various indices derived there from provide inexpensive ways of evaluating the elastic properties of bone.

Using small tubes to measure root elongation of newly germinated alfalfa seedlings in relation to moisture

A method of growing newly germinated seedlings in small tubes was developed to enable the study of early root elongation. Three newly germinated alfalfa (Medicago sativa L.) seeds were placed in tubes of various diameters and volumes filled with sand at several moisture tensions, and the tubes were sealed to prevent moisture loss. For the first 4 d, roots elongated at approximately 8 mm d−1 in polyvinyl chloride plastic tubes holding 60 mL of sand with a moisture tension of 100 kPa or less. After the initial 4 d, root elongation continued at a slower rate, and branch roots developed before termination of the experiments at 12 d after germination. At a moisture tension of 300 kPa, root elongation was markedly less than at 100 kPa, and was zero at moisture tensions of 500 kPa or greater. In round-bottom glass tubes, root elongation rate was significantly slower in a sand volume of 23 mL than in 65 mL, and there was evidence of slower seedling development as the diameter of the tubes was reduced from 20 to 15 mm. Wax plus masking tape or nylon tape were equally effective in sealing the sides of tubes formed from the two halves of a plastic pipe previously cut lengthwise. A plastic cap plus wax was significantly better than plastic film for sealing the bottom ends of plastic tubes. Neither aeration nor replacement of water with a dilute nutrient solution had an effect on root elongation of young seedlings. Key words: Alfalfa, seedling, root elongation, moisture stress, Medicago sativa

A New Doppler-Echo Method to Quantify Regurgitant Volume

An in vitro technique using color flow imaging and continuous wave Doppler was developed to measure the initial regurgitant flow jet diameter and velocity integral to yield the parameters for a volume calculation. Jets were produced by volume-controlled injection through tubes of various diameters (1.3, 1.9, 2.8, and 3.5 mm) to deliver volumes from 1 to 7 ml over 100 to 300 msec at pressures from 40 to 200 mm Hg. One hundred forty-five samples were obtained. Flow jet diameter consistently overestimated tube diameter by 2 mm when injected volume was 1.5 to 7 ml and by 1.5 mm when injected volume was less than 1.5 ml. This offset was stable with various transducers (2.5, 3.5, 5.0 MHz) at normal gain setting (just under noise). Therefore, corrected flow jet diameter (FJD) = FJD - 2 mm, and Doppler volume = corrected flow jet area x velocity integral. A range of injectates from 1.1 to 7 ml generated Doppler volume of 1.0 to 8.2 ml. The relation between Doppler volume (DV) and injected volume (IV) was DV = 1.079 IV - 0.22, r2 = 0.945, p less than 0.01. This relation was not altered by tube diameter. Thus a method combining color flow imaging and continuous wave Doppler provides a reliable and accurate measure of in vitro flow volume.

Infiltration of fine capillaries by a Ga-In melt under the action of ultrasound

The authors use quartz capillary tubes of various diameters to investigate the feasibility of enhancing the diffusion of a liquid gallium-indium alloy and the ability of the alloy to impregnate sintered materials by the application of ultrasound. They discuss the diffusion variations relative to pressure, friction, surface tension, and tube diameter or pore size considerations and conclude that the use of ultrasound makes it possible, without the application of heat, to impregnate sintered materials with pore sizes ranging down to 1 micrometer with the gallium-indium alloy to depths ranging from 0.8 to 30 millimeters.

Residual Stresses in Welded Tubular T-joints

Many off-shore structures of fixed or mobile platforms, are mainly composed of tubes of various diameters. The structures have many tubular joints called nodes, where two tubes or more connected together with welding in the same space. Due to the weld, there are residual stresses in tubular joints. It is said that the residual stresses have bad effects on static and fatigue strength of the joints. However, few investigations have been carried out for the problem of residual stresses in welded tubular joints. So, it has been almost imposible to take residual stresses into consideration when designing the joints.This paper deals with the residual stresses in welded tubular T-joint, that is the most simple and popular type of the tubular joints. Experimental and analytical results are shown. Residual stresses of two specimens are measured. One specimen has 700 mm diameter chord and 400 mm diameter brace, another has 700 mm diameter chord and 300 mm diameter brace. FEM with shell elements is used for the full model analysis. Then, plane strain elements are used to perform the analysis of weld toes. Both experimental and analytical results are thoroughtly agreed for the most part.

Red cell aggregation as a cause of blood-flow echogenicity.

The role of red cell aggregation as a cause of ultrasonic echogenicity in flowing blood was evaluated by in vitro experiments using fresh human blood. Blood was circulated in tubes of varying diameter (12 mm to 6 mm). In all experiments, echogenicity increased as blood approached static conditions. Echogenicity was greater in tubes with a larger diameter over the same range of blood velocity. However, echogenicity in tubes of various diameters was the same when evaluated in terms of shear rate. Thus, shear rate and not velocity is the flow condition that determines echogenicity. Since shear rate determines the degree of red cell aggregation, while other conditions affecting red cell aggregation (hematocrit, erythrocyte membrane conditions, and plasma macromolecules) are held constant, we conclude that these results provide additional evidence that red cell aggregation is a cause of echogenicity in flowing blood. Furthermore, a red cell aggregation mechanism for blood-flow echogenicity would explain the increased prominence of internal echoes in lower shear rate venous blood flow compared with those of higher shear rate arterial blood flow.

Investigation of lasing in active media utilizing transitions in manganese atoms

A study was made of the energy characteristics and spectral composition of the radiation emitted by self-heating manganese vapor lasers as a function of their active-medium parameters and excitation conditions in discharge tubes of various diameters. The dependences obtained were used as a basis for discussing the lasing mechanism. The relationship was considered between the elementary processes occurring in the pulsed plasma discharge and the parameters of the emitted radiation. A total laser output power of 12 W, at an efficiency of 0.3%, was obtained in a 2-cm diameter tube of 200 cm3 volume.

Influence of the contraction ratio in elongational flow of polymer solutions

Using upstream chambers and capillary tubes of various diameters D 0 and D respectively, it is shown that the excess pressure drop Δ P e, associated with the elastic properties of polymer solutions, varies with the contraction ratio D 0/ D. This variation is such that Δ P e first increases and then decreases as D 0/ D increases. The analysis of previous and present results indicates that the polymer solution's flow configuration in the upstream chamber is responsible for the observed dependency.

On thin rings and short tubes subjected to centrally opposed concentrated loads

The deformation behaviour of mild steel rings and short tubes of various diameters, thicknesses and lengths loaded centrally by opposed conically-headed cylindrical punches is examined. The test equipment and procedure are briefly described and typical histories of deformation, punch load—displacement diagrams and the increase in the horizontal ring or tube radius for increasing punch travel are presented. A comparison is made between the latter and those predicted by use of a simple expression based on the assumption of rigid-plastic material deformation. Good correlation is obtained with rings of different diameter to thickness ratio.

Modified Tube Diameters for the Double‐Tube Apparatus

AbstractExperiences with the double‐tube method indicated that the diameter of the outer tube should be larger than the theoretical minimum because of soil disturbance in the annular space between the inner and the outer tube. Field studies were conducted in Adelanto loam and in river sand using outer tubes of various diameters in combination with an inner tube with a constant diameter. The results indicated that, for an inner‐tube diameter of 12.7 cm, an outer‐tube diameter of 25.4 cm was sufficient to eliminate most of the effects of soil disturbance in the measured value of the hydraulic conductivity. Values of 10.2 cm and 20.3 cm for the diameters of the inner and outer tubes, respectively, also appeared to be satisfactory.

Slippage of Water over Nonwettable Surfaces

When water flows over glass which has been treated with the vapor of dimethyldichlorosilane and thus made water repellent, slipping on the boundary between the solid surface and the water takes place. This is is shown in capillary tubes of various diameters. The amount of slipping is small, but measurable. It disappears or becomes extremely small in case of turbulent flow.

Measurement of Water Equivalent of Snow Cover by the Snow Tubes of Various Diameters

For the study of the relation between the weight of snow cover per unit area Measured by a snowtube and the inner diameter of the tube, the authors carried samplings by some snow-tubes of different diameters.When the layer of granular snow existed in the snow cover, there were contraction on the length of the snow core sampled in the snow-tube and the decrease in the weight of the sampled snow per unit area compared with the depth and the weight per unit area of the snow cover ; the smaller the inner diameter of the tube, the more the length contracted and the weight decreased.These phenomena were not found in case the layer of granular snow did not exist, therefore the authors concluded that these phenomena were concerned with the flow out of the grain of snow from the sampling domain in the layer of the granular snow while sampling.From samplings of the snow cover of about 40cm depth by two snow-tubes of different inner diameter (76. 9mm and 23. 7mm), it was found that the ratio of the length of snow cores correlated fairly well with the ratio of the weight of sampled snow per unit area.The relations were given by the following empirical formula.m-Δm1(h-a1)=m-Δm2(h-a2)where m; weight of snow cover per unit area, h; depth of snow cover, Δm1, Δm2; decrease of the weight of snow per unit area from m measured by the snow-tubes of inner diameters φ1 and φ2.a1, a2; contraction of the length of snow core from h in the snow tubes of inner diameters φ1 and φ2.

Studies on Overholding in High-Temperature Short-Time Pasteurizers Operated on Water

Summary The flow of water at 160° F. through holding tubes of various diameters has been studied by tracing the movement of charges of salt solution introduced into the inlet ends of the tubes. The results indicate that any given quantity of material entering a holding tube is spread out considerably and that parts of it remain in the tube for longer periods than do other parts. Any material that remains in the holding tube for longer than the desired holding time is overheld. The data presented show quantitatively the amount of fluid overheld for various times in holding tubes of 1-in., 1½-in., and 2½-in. sanitary metal pipe. Overholding was found to diminish with increasing velocity in a given size of pipe and, at a constant velocity, to diminish as the size of the pipe decreased. For a given flow rate, therefore, overholding can be minimized by constructing the holding tube of the smallest practical size of pipe.

The interpretation of observed pressure gradients in laminar flow of non-newtonian liquids through tubes

It is possible to detect anomalous flow of a non-Newtonian liquid near a rigid boundary, by plotting the apparent fluidity (as given by Poiseuille's formula) against the reciprocal of the shear stress at the wall in laminar flow through tubes of various diameters. This method of plotting has some advantages over others. If the properties of the liquid in shear are everywhere specified by a unique stress/rate-of-strain relationship, all the plotted points should lie on a single curve, and a wall effect is indicated if distinct curves arise from different diameters of tube. It is shown that a wall effect can be measured by an effective slip coefficient, which is a function of the stress at the wall. The mathematical argument is based on the assumptions (i) that the flow is rectilinear, (ii) that there is no actual slip at the wall, and (iii) that the functional relationship between stress and rate-of-strain is dependent on the normal distance from a solid boundary, in a thin layer of liquid near the boundary only.

Testing machine for glass tubing and rod

An apparatus is described for testing the strength of glass tubing or rod of ordinary dimensions. The maximum strain in the tube at the moment of fracture is used as a criterion of the strength of the glass. A bending moment is applied to the two ends of the specimen, and the breaking strain is derived from a determination of the radius of curvature immediately before fracture. Some results of tests on glass tubes of various diameters are given, and a comparison of tests on annealed and unannealed tubing.

V. On stratified discharges. —II. Observations with a revolving mirror

In a paper published in Poggendorff's ‘Annalen,’ Jubelband, p. 32, A. Wüllner has described a series of observations made, by means of a revolving mirror, upon the discharge of a large induction-coil through tubes containing ordinary atmospheric air at various degrees of pressure. When, as is generally the case with an induction-spark, the discharge occupies an appreciable interval of time, the image in the mirror appears spread out to a breadth proportional to the duration and to the velocity of rotation. The successive phases of the phenomena then appear, as usual, arranged in successive positions, and may be studied separately, even when too rapid to be disentangled by the unassisted eye. Wüllner’s observations appear to have been directed rather to the nature of the coil-discharge than to that of the stratifications; and some of his principal conclusions are accordingly of the following kind, viz. that at low pressures, i. e . down to 1 millim., when the discharge was stratified, the striæ showed an intermittence of intensity indicating either a pulsation within the duration of the main discharge or a breaking up of the main into a series of partial discharges. At greater pressures, e. g . at 26 millims., when almost all trace of stratification was lost, this breaking up into partial discharges (especially at the commencement) was distinctly perceptible. At yet greater pressures, i. e . from 40 millims. to 75 millims., a cloudy kind of stratification showed itself; but, excepting a bright flash at the outset, no appearance of partial discharge was visible. The observations, which were at first directed to capillary tubes, were extended to tubes of various diameters, and also included the effect of a magnet on the discharge.

Account of a series of experiments, undertaken with the view of decomposing the muriatic acid

Account of a Series of Experiments, undertaken with the view of decomposing the Muriatic Acid. By Mr. William Henry. Communicated by the Right Hon. Sir Joseph Banks, Bart. P. R. S. In the introduction to this paper the author points out the great utility that would accrue to chemical science, were it possible to arrive at a complete analysis of certain acids, since the new, and indeed every system of chemistry, will ever be incomplete and liable to subversion till the particular agents here alluded to have been resolved into their constituent principles. The obstacles, however, which impede the progress of this investigation, are much greater than may appear at first sight; and among these are particularly mentioned the difficulty of obtaining the acids completely separated from all other substances, which, by their presence, will ever tend to introduce uncertainty into the results of the process; it being observed that the attraction between compound particles at all times increases in proportion as we recede from the point of saturation, and that the smallest remnant is often sufficient to perplex all further analysis. The liquid state is thought to be totally unfit for the purpose of this inquiry: and after some other strictures, it is shown that the state of the gas is the only one in which acids can become proper objects of analytical investigation. In the series of his experiments on the muriatic acid in the gaseous state, Mr. Henry employed the electric fluid as an agent much preferable to artificial heat. “This mode of operating,” he says, “enables us to confine accurately the gases submitted to experiment; the phenomena that occur during the process may be distinctly observed, and the comparison of the products with the original gases may be instituted with great exactness.” The action of the electric fluid itself, as a decomponent, is no doubt extremely powerful; since it is capable of separating from each other the constituent parts of water, of the nitric and sulphuric acids, of the vegetable alkali, of nitrous gas, and of several other bodies whose components are known to be strongly united. The experiments were made in straight glass tubes of various diameters, urine d at the sealed end with a metallic conductor, through which the shocks were introduced, the gas being at the other end confined by quicksilver.