Effect of measurement volume size on turbulent flow measurement using ultrasonic Doppler method

This paper presents the results of an investigation on the effects of measurement volume size on the mean velocity profile and the Reynolds stress for fully developed turbulent pipe flows. The study employs the ultrasonic velocity profile method, which is based on the ultrasonic Doppler method. The ultrasonic Doppler method offers many advantages over conventional methods for flow rate measurement in the nuclear power plant piping system. This method is capable of measuring the instantaneous velocity profile along the measuring line and is applicable for opaque liquids and opaque pipe wall materials. Furthermore, the method has the characteristic of being non-intrusive. Although it is applicable to various flow conditions, it requires a relatively large measurement volume. The measurement volume of the present method has a disk-shape determined by the effective diameter of the piezoelectric element and the number of the wave cycles of the ultrasonic pulse. Considering this disk-shaped measurement volume and expressing the time-averaged velocity in a truncated Taylor series expansion around the value at the center of the measuring control volume, the value of the velocity can be obtained. The results are then compared with the data obtained from DNS and LDA measurements. The result shows that the effect of the measurement volume size appears in the buffer region and viscous sublayer.     

Marfan syndrome in Europe

OBJECTIVES: Marfan syndrome (MFS) is a relatively frequent systemic connective tissue disorder with an important physical morbidity and mortality. The influences of MFS on physical problems, perception of severity, and impact on the quality of life and psychosocial well-being have been studied only limitedly. The aim of this study was to assess the association between the severity derived from the reported symptoms and subjectively experienced severity of MFS (expressed as a global judgment), with special emphasis regarding impact on relationships and pregnancies, psychosocial adjustment, and differences between the seven European countries. METHODS: A questionnaire designed specifically for this study and translated in each of the native languages was sent to 2,080 members of one of the patient support groups in Belgium, Denmark, France, Germany, The Netherlands, Switzerland, and the United Kingdom. 857 MFS patients of 13 years and older completed the questionnaire and were included in the data analysis. RESULTS: Physical impairments were scored by perception of severity of physical symptoms by the patients (physical severity perception score) and by their perception of the influence of MFS on their life (subjective severity score). Main discrepancy between physical severity perception and subjective severity score was the higher percentage of patients scoring in physical severity perception as severe (53.5%) compared to subjectively severe (26.5%). 61% of those who scored on the physical severity score as severely affected were designated as being mildly-moderately affected on subjective scoring. Both severity scores increased significantly with age. Two hundred-twenty women have carried 430 pregnancies (1.95 pregnancies/woman), with cardiovascular complications in 1.6%. Prenatal studies for MFS were rejected by 7.6% of MFS patients of 25 years and older, 33.6% were undecided, and 48.5% favored prenatal diagnosis for MFS if available. A positive general self-image was reported by 91.5% of patients. However, more than 90% stated that MFS had a negative influence on their sexual relationships, which they ascribed to negative perception of their body image. CONCLUSIONS: MFS has significant impact on daily life activities, but the majority of patients come to terms with their condition. Acceptance is mainly determined by subjective severity, and less by physical symptoms as reported by the patients themselves. It is important to stimulate a positive attitude towards MFS.     

Calculation of vibrations of thin plates by partitioning into elastically connected undeformable units

A mathematical model of a thin plate in the form of a system of elastically connected undeformable rectangular units is proposed and substantiated. With necessary additions, the basic statements of the method can be extended to the case of a thick plate. Novosibirsk State Engineering University, Novosibirsk 630092. Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 39, No. 5, pp. 159–168, September–October, 1998.     

The Hungarian periconceptional service as a model for community genetics

OBJECTIVES: This review describes the methods and results of the Hungarian periconceptional service consisting of counselling, examinations and medical interventions. (The term periconceptional is used instead of preconceptional because the early postconceptional period is also involved to this service.) METHODS: The service was based on three steps: check-up examination of reproductive health (i.e., preconceptional screenings), a 3-month preparation for conception, dispensed and/or supervised by qualified nurses, and a better protection in early pregnancy for the most sensitive early development of the embryo for voluntary and eligible couples. RESULTS: Experiences from the coordinating centre of the Hungarian periconceptional service are summarized between February 1, 1984, and January 31, 1999, thus 15 years. Participants with positive family histories, case histories and subjects with genito-urinary infections had a more effective flow towards secondary care. Infertile couples were diagnosed and treated sooner. The periconceptional service is effective for the introduction of periconceptional folic acid-containing multivitamin supplementation and for the reduction of smoking and alcohol consumption in females in the preconceptional period. The rate of major congenital abnormalities (20.6 per 1,000) was significantly lower than expected. CONCLUSIONS: The periconceptional service is feasible and has many benefits. Thus, proper preparation for conception is the earliest and probably the most important effort to prevent genetic diseases.     

Kinetic equations for a finely dispersed rarefied gas suspension

Starting from the Liouville equation, the kinetic equations for a finely dispersed rarefied gas-particle medium are derived. The size of the suspension particles is assumed to be much less than the free path of the gas molecules, while their density is so small that interaction between the particles can be neglected. It is shown that in general the dynamics of this gas suspension can be described by a system of two kinetic equations, which differ radically from the Boltzmann equations. Novosibirsk. Translated from Izvestiya Rossiiskoi Akademii Nauk, Mekhanika Zhidkosti i Gaza, No.2, pp. 165–171, March–April, 1994.     

Aerodynamic characteristics of a delta wing in hypersonic flow

Novosibirsk. Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, No. 2, pp. 66–69, March–April, 1994.     

Exact solution of the problem of convective heat exchange for a circular cylinder at small Prandtl numbers

The problem of the heat exchange of a circular cylinder in an incompressible flow at small Prandtl numbers Pr ≪ 1 is solved. Moscow. Translated from Izvestiya Rossiiskoi Akademii Nauk, Mekhanika Zhidkosti i Gaza, No. 1, pp. 43–48, January–February, 1994.     

Asymptotic model of active resonance absorber of acoustic vibrations in a closed region

Novosibirks. Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, No. 6, pp. 44–55, November–December, 1994.     

On the nonlinear interfacial instability of rotating core-annual flow

The interfacial stability of rotating core-annular flows is investigated. The linear and nonlinear effects are considered for the case when the annular region is very thin. Both asymptotic and numerical methods are used to solve the flow in the core and film regions which are coupled by a difference in viscosity and density. The long-time behavior of the fluid-fluid interface is determined by deriving its nonlinear evolution in the form of a modified Kuramoto-Sivashinsky equation. We obtain a generalization of this equation to three dimensions. The flows considered are applicable to a wide array of physical problems where liquid films are used to lubricate higher- or lower-viscosity core fluids, for which a concentric arrangement is desired. Linearized solutions show that the effects of density and viscosity stratification are crucial to the stability of the interface. Rotation generally destabilizes nonaxisymmetric disturbances to the interface, whereas the centripetal forces tend to stabilize flows in which the film contains the heavier fluid. Nonlinear effects allow finite-amplitude helically traveling waves to exist when the fluids have different viscosities.This research was partially supported by the National Aeronautics and Space Administration under NASA Contract No. NAS1-18605 while the second author was in residence at the Institute for Computer Applications in Science and Engineering (ICASE), NASA Langley Research Center, Hampton, VA 23665. This work was also supported by the Science and Engineering Research Council.