Void Rate Research Articles

Study in a UHF electromagnetic resonant cavity of a bubble field induced by ultrasonic cavitation

A method founded on the follow-up of an electromagnetic cavity resonant frequency working round 390 MHz has been carried out in order to measure the void rates of bubble field induced by a 308 kHz ultrasonic cavitation in liquids. This method can detect void rates as low as 2 × 10 −5 . The experimental set up permits to study the influence of some experimental parameters on the void rate, such as the acoustic power, the acoustic irradiation duration, and the dissolved gas concentration in the liquid. Moreover, an estimation of the bubble size distribution is obtained. The extension of the method to open resonators and the possibility to observe the fast evolutions of the void rate are considered.

COMPARISON OF URODYNAMIC AND FREE VOIDING PATTERN IN INFANTS WITH DILATING REFLUX

Purpose We compared simultaneous investigations of free voiding pattern and urodynamic assessment in infants with dilating reflux to obtain further information on previously suspected bladder dysfunction based on abnormal urodynamic findings. Material and Methods A total of 33 male and 8 female infants with dilating reflux were included in the study. Free voiding pattern was determined by 4-hour voiding observation compared to previously described voiding pattern studies of healthy infants. Simultaneous invasive urodynamic assessments were performed. Results The patients were grouped according to urodynamic bladder capacity. Half of the male patients had low bladder capacity with high voiding pressure levels (hypercontractile) and the other half had either normal or high capacity bladder. The low capacity group had frequent small voids and a high rate of interrupted voiding, the high capacity group had infrequent voids of high volumes with high residual urine, and the pattern of the normal capacity group differed only from that of healthy infants by an increase in residual urine. All female infants had the typical characteristics of high capacity bladder on free voiding and urodynamic assessments. Conclusions Infants with abnormal invasive urodynamic investigations, including those with a small capacity hypercontractile bladder and those with a high capacity bladder, could be identified on free voiding studies, indicating that an abnormal urodynamic pattern represents bladder dysfunction.

Study of the correlations between the cavitation noise power and bubble volume rate in an acoustic cavitation bubble field

The effects of ultrasound cavitation depend on both the insonification conditions and the liquid characteristics, by means of their influence on the bubble cloud. For this reason, the study of the cavitation bubble field is of interest. The implemented hyperfrequency method allows the monitoring of the bubble volume rate, called void rate a, during the insonification, versus acoustic pressure or dissolved air concentration in water. On the other hand, the oscillating behavior of bubbles found expression in a characteristic acoustic spectrum. The cavitation noise power, defined as the integral of the cavitation acoustic spectrum, permits the estimation of the importance of the dynamic activity of the bubble field. The aim of this paper is to set the relations between the void rate evolution and the cavitation noise power. The evolutions of the cavitation noise power versus the void rate will be examined in two situations, whether the void rate evolution is due to the acoustic pressure variation or to a change of the dissolved air content in water. A link between the cavitation noise power and the increased speed of the void rate will be set.

Influence of characteristic parameters on the void rate in an acoustic cavitation bubble field

Among the causes of the cavitation effects dispersion, bubble field plays an important role. Not only are its bubbles responsible tor most of the effects, but moreover they modify the wave which activates them. It is difficult to determine the bubble sizes and their distribution, but their overall volume can be determined with a hyperfrequency technique presented in this paper. The void rate is not described in any ultrasonic cavitation or bubble-wave interaction theory. Nevertheless, its determination is an innovative and important tool to describe and to characterize bubble fields in ultrasonic cavitation phenomena. Maximum void rate evolution is examined as a function of the insonification duration, of the acoustic pressure amplitude and of the initial air content in water.

The plastic instability behaviour of laser-textured steel sheet

As the production of a new technique that can offer both good formability and high image clarity for texturing metal sheet, laser-textured sheet has attracted the attention of many manufacturers and users. Among the many subjects to be studied, plastic instability behaviour of the laser-textured sheet is one of most important to understand its ability in extending material ductility and to appropriately control this technique. Experimental investigations are carried out in this paper to study the macroscopic behaviour and microstructural mechanism of the laser-textured sheet, and comparison is made with the normal sheet taken from the same coil of metal sheet. It is demonstrated that, the difference in the behaviour of plastic instability obviously shows tendency to delay strain localization and the onset of thickness necking. Shear banding and internal void damage are spread to a much wider region in the sheet being laser-textured. The prestrained microcraters enforced on the surface of the textured sheet act as hardening spots, which are likely to share out deformation and inhibit the increasing rate of voiding, and eventually favouring the ductility of the material used.

Daily Rhythms in Rates of Glomerular Filtration and Cloacal Excretion in Captive and Wild Song Sparrows (Melospiza melodia)

We infused polyethylene glycol (PEG) into laboratory-housed song sparrows (Melospiza melodia) via intraperitoneally implanted osmotic minipumps. The plasma concentration of PEG was significantly higher at the end of the dark phase of the photoperiod than at the end of light, indicating a nighttime reduction in the rate of glomerular filtration (GFR, the route of PEG elimination). The rate of cloacal voiding of PEG also varied through the day. The rate was similar to the rate of PEG infusion from the minipump during most of the daylight hours. However, PEG excretion was signifcantly reduced during the dark phase and elevated during the first hours of light, a pattern that resulted from sequestering urine in the lower intestine during the night. To examine patterns of osmoregulation in the field, we also implanted minipumps into free-living sparrows. One to fiue days later we recaptured the birds and measured concentrations of PEG in plasma and urine. As in the laboratory, the GFR (and urine flow rate) tended to be lowest in the early morning and higher later in the day. This nocturnal reduction in GFR and cloacal voiding should contribute to minimizing water losses during the night.

A Consumer's Guide to Commercially Available Urodynamic Equipment

Eight commercially available urodynamic machines from 6 major manufacturers (Aspen Medical, Dantec, Electro-Medical Supplies (EMS), Uro-gyn, Ormed and Wiest) were assessed for accuracy, construction and user-friendliness. There was less than 10% inaccuracy with regard to fill volume, void rate and pressure measurements. The Wiest 6000 plus system was between 11 and 14% inaccurate during voided volume measurement and other systems were less than 10% inaccurate. User-friendliness was assessed during routine cystometry and is mainly dependent on the software supplied with the equipment. The merits and faults of each urodynamic system with regard to performing a urodynamic investigation, running a urodynamic service and data management are compared with an "ideal" urodynamic system.

Empty Dwellings: The Use of Rating Records in Identifying and Monitoring Vacant Private Housing in Britain

In recent years there has been growing political concern with questions of effective stock utilization and the issue of empty housing. However, our knowledge of the scale and nature of the problem remains limited, particularly as regards the private sector. There is a dearth of reliable information on privately owned vacant property, which undermines local policy responses. One source of information which is available to local authorities are local rating records, which are often used as the basis for calculating a void rate. However, in this paper it is shown, by reference to recent work in one inner London borough, that such records are likely to provide a serious underestimate of the problem. In their present form, rating records, though potentially valuable, are a far from adequate data source for identifying and monitoring vacant private-sector dwellings.

Fetal Swallowing and Voiding in Relation to Hydramnios

Fetal swallowing and voiding were measured using colloidal gold and an ultrasonic scanner, respectively. Subjects in the study were in their 38-40th week of pregnancy. Cases were divided into 3 groups: normal, hydramnios, and oligohydramnios. The normal group had a mean swallowing rate of 198 ml/day and a mean voiding rate of 23.6 ml/hr. No significant differences were found among these rates and the corresponding rates in the other 2 groups. It is concluded that mechanisms other than fetal swallowing and voiding can contribute to the control of amniotic fluid volume at term.

Space-Time Dynamics of a Fast Breeder Reactor for Localized Disturbances

A method of analysis is developed for nuclear reactor accident initiating events that are localized in space. The method is based on a flux factorization technique, accounting for the flux shape changes taking place near the region of perturbation. In the steady state, the neutron shape functions are expanded in a series of eigenfunctions of the steady-state group removal operator. During the unsteady state, the time-dependent group shape functions are expanded in a series of the same stationary eigenfunctions with time-dependent Fourier coefficients. An auxiliary function is added to this expansion to take account of the spatial variation of the spectral hardening of neutrons in the immediate vicinity of the disturbed region. From the resulting representation of the group shape functions, the equations to be satisfied by the time-dependent Fourier coefficients and the time-dependent auxiliary shape function due to the disturbed region are developed consistently. A typical large [1000-MW(e)] liquid-metal fast breeder reactor with two radial core zones of different enrichments is analyzed by the above method. The transient initiating perturbation is taken to be a specified rate of coolant voiding from a single subassembly in the reactor core. The results show a strong dependence of the reactivity added on the radial location of the voiding perturbation and on the rate of voiding.

The theory of void and interstitial dislocation loop growth in irradiated metals

Abstract The nucleation and growth kinetics of voids and interstitial dislocation loops in irradiated metals is theoretically considered. Taking into account a slight dependence of void swelling on the void concentration the void and dislocation loop nucleation rates are approximated by expressions allowing an analytical treatment of the problem. It is shown that a sufficiently high doses the maximum void swelling depends on the number of displacements produced by bombarding particles only. The equations for dependence of void and dislocation loop concentration and void swelling on dose are derived. The mechanism of void swelling saturation due to ceasing of loop growth at large doses is discussed.

On the Use and Performance of Error-Voiding and Error-Marking Codes

In contrast to payroll or inventory data, which must reach the recipient in its entirety, there is another class of data that includes radar-tracking data, remote-sensory data or control data, etc., for which the requirement of completeness is not so stringent. Error control for this class of data may be accomplished by forward-acting error-correcting codes which void or mark any detected errors that they do not correct. In order to evaluate these error-voiding methods, the error rates for such codes are estimated in this paper using the error statistics of the Alexander-Gryb-Nast study. A class of 18 (about 50 percent redundant) cyclic codes capable of correcting from one to five errors and having block lengths from 15 to 47 bits is examined. Only bounded-distance decoding is evaluated, but each code is assigned each possible decoding radius up to the maximum permissible radius determined by the capability of the code. Since interleaving generally reduces error rates, the error rates for this class of codes are estimated for interleaving constants from 50 to 300 in steps of 50. It is concluded that: (i) If voids are permissible (at a rate of about 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−4</sup> ) then low undetected-error rates may be achieved by a code capable of correcting many errors but used to correct only two or three errors. Such a code might be about 50 percent redundant and have a block length between 25 and 50 bits. (ii) It is impractical to obtain low void rates. If voids are not tolerable, then retransmission is required to obtain low error rates. (iii) Interleaving is more effective with codes correcting three (or more) errors than with those correcting only single or double errors.