Nonlinear acoustic waves in channels with variable cross sections

The point symmetry group is studied for the generalized Webster-type equation describing non-linear acoustic waves in lossy channels with variable cross sections. It is shown that, for certain types of cross section profiles, the admitted symmetry group is extended and the invariant solutions corresponding to these profiles are obtained. Approximate analytic solutions to the generalized Webster equation are derived for channels with smoothly varying cross sections and arbitrary initial conditions.Comment: Revtex4, 10 pages, 2 figure. This is an enlarged contribution to Acoustical Physics, 2012, v.58, No.3, p.269-276 with modest stylistic corrections introduced mainly in the Introduction and References. Several typos were also correcte

Aeroacoustics of the swinging corrugated tube: Voice of the Dragon

When one swings a short corrugated pipe segment around one’s head, it produces a musically interesting whistling sound. As a musical toy it is called a “Hummer” and as a musical instrument, the “Voice of the Dragon.” The fluid dynamics aspects of the instrument are addressed, corresponding to the sound generation mechanism. Velocity profile measurements reveal that the turbulent velocity profile developed in a corrugated pipe differs notably from the one of a smooth pipe. This velocity profile appears to have a crucial effect both on the non-dimensional whistling frequency (Strouhal number) and on the amplitude of the pressure fluctuations. Using a numerical model based on incompressible flow simulations and vortex sound theory, excellent predictions of the whistling Strouhal numbers are achieved. The model does not provide an accurate prediction of the amplitude. In the second part of the paper the sound radiation from a Hummer is discussed. The acoustic measurements obtained in a semi-anechoic chamber are compared with a theoretical radiation model. Globally the instrument behaves as a rotating (Leslie) horn. The effects of Doppler shift, wall reflections, bending of the tube, non-constant rotational speed on the observed frequency, and amplitude are discusse

Finite-dimensional turbulence of planetary waves

Finite-dimensional wave turbulence refers to the chaotic dynamics of interacting wave "clusters" consisting of finite number of connected wave triads with exact three-wave resonances. We examine this phenomenon using the example of atmospheric planetary (Rossby) waves. It is shown that the dynamics of the clusters is determined by the types of connections between neighboring triads within a cluster; these correspond to substantially different scenarios of energy flux between different triads. All the possible cases of the energy cascade termination are classified. Free and forced chaotic dynamics in the clusters are investigated: due to the huge fluctuations of the energy exchange between resonant triads these two types of evolution have a lot in common. It is confirmed that finite-dimensional wave turbulence in finite wave systems is fundamentally different from kinetic wave turbulence in infinite systems; the latter is described by wave-kinetic equations that account for interactions with overlapping quasiresonances of finite amplitude waves. The present results are directly applicable to finite-dimensional wave turbulence in any wave system in finite domains with three-mode interactions as encountered in hydrodynamics, astronomy, plasma physics, chemistry, medicine, etc

Development of the A/H6N1 influenza vaccine candidate based on A/Leningrad/134/17/57 (H2N2) master donor virus and the genome composition analysis using high resolution melting (HRM)

The avian influenza viruses of H6N1subtype present a potential danger for humans. The cold-adapted (ca) reassortant influenza virus А/17/herring gull/Sarma/2006/887 (H6N1) was obtained in chicken embryos by the genetic reassortment based on the coldadapted A/Leningrad/134/17/57 (H2N2) master strain. The genome composition of the obtained reassortant was analyzed by means of real-time PCR with the high resolution melting (HRM) analysis using the intercalating fluorescent dye EvaGreen. Analysis of the gene segments showed that the reassortant А/17/herring gull/Sarma/2006/887 (H6N1) contains the internal proteins coding genes (PB2, PB1, PA, NP, M, and NS) of the master donor virus and the surface antigens coding genes of the A/herring gull/Sarma/51c/2006 (H6N1) avian influenza virus. The study of the phenotypic properties showed that the virus А/17/herring gull/Sarma/2006/887 (H6N1) is temperature sensitive (ts), ca in chicken embryos, and attenuated in mice when administered intranasally. This reassortant can be recommended as a live influenza vaccine candidate for humans.The avian influenza viruses of H6N1subtype present a potential danger for humans. The cold-adapted (ca) reassortant influenza virus А/17/herring gull/Sarma/2006/887 (H6N1) was obtained in chicken embryos by the genetic reassortment based on the coldadapted A/Leningrad/134/17/57 (H2N2) master strain. The genome composition of the obtained reassortant was analyzed by means of real-time PCR with the high resolution melting (HRM) analysis using the intercalating fluorescent dye EvaGreen. Analysis of the gene segments showed that the reassortant А/17/herring gull/Sarma/2006/887 (H6N1) contains the internal proteins coding genes (PB2, PB1, PA, NP, M, and NS) of the master donor virus and the surface antigens coding genes of the A/herring gull/Sarma/51c/2006 (H6N1) avian influenza virus. The study of the phenotypic properties showed that the virus А/17/herring gull/Sarma/2006/887 (H6N1) is temperature sensitive (ts), ca in chicken embryos, and attenuated in mice when administered intranasally. This reassortant can be recommended as a live influenza vaccine candidate for humans

Secretory activity of gastroduodenal zone before and after cholecystectomia

Вивчено функціональні особливості секреторної активності гастродуоденальної зони до та піс­ля холецистектомії. Встановлено пригнічення ферментовидільної функції шлунка у хворих із постхолецистектомічним синдромом. З’ясовано, що наявність дуодено-гастрального рефлюксу свідчить про дуоденостаз і недостатність замикальної функції пілоричного сфінктера. У хворих видалення жовчного міхура призводить до аритмії циркадних і ультрадіадних ритмів усієї травної системи й, у тому числі, до порушень активності секреторних залоз шлунка.Изучены функциональные особенности секреторной активности гастродуоденальной зоны до и пис¬ля холецистэктомии. Установлено угнетение ферментовыводящей функции желудка у больных с постхолецистэктомический синдромом. Выяснено, что наличие дуодено- гастральной рефлюкса свидетельствует о дуоденостаз и недостаточность замыкательной функции пилорического сфинктера. У больных удаление желчного пузыря приводит к аритмии циркадных и ультрадиадних ритмов всей пищеварительной системы и, в том числе, к нарушениям активности секреторных желез желудка.Functional features of the gastroduodenal zone secretory activity before and after cholecystectomia were studied. The oppression of the stomach enzymatic secretion in patients with postcholecystectomia syndrome was established. The presence of duodeno-gastral reflux testifies to the duodenostasis and incompetence of closing function of the pyloric sphincter. Cholecystectomia entails the arrhythmia of circadian and ultradian rhythms of the whole digestive apparatus, including the derangements of the stomach secretory glands

Interconnection between aggression and protection factors of gastric juice and oral liquid of the patients with precancerous changes of gastric mucosa

This article is about learning of the aggression factors and the gastric juice and oral liquid protection of the patients with precancerous changes in the mucous gastric membrane of stomach. 32 middle-aged people were researched, who were at the inpatient treatment at the SI “Institute of Gastroenterology of NAMS of Ukraine”: 6 of them were with the atrophic changes of mucous membrane of stomach with different rate of severity (the I group), 12 people were with the intestinal metaplasia in the antrum (the II group), 14 patients were with intestinal metaplasia in the body and in the antrum of mucous membrane of stomach (the III group). The diagnosis was established after meticulous endoscopic and histological researches of biopsy material of mucous membrane of stomach. During the esophagogastroscopic research the gastric juice was being collected. It was determined its pH, pepsin, glycoprotein, sialic acids, fucose and hexosamines concentration. Also there were conducted the investigations of oral liquid, where the content of glycoprotein, sialic acid, fucose and hexosamines was determined. In the gastric juice of patients of the II and III groups, the content of sialic acids was increased, in the III – the acid secretion increased the hexosamines, with anacid – of fucose and it was decreased the amount of pepsin. In the oral liquid, the content of sialic acids in all researching groups was increased, fucose - only in the I group, hexosamines and glycoproteins - only in the III group. The further complex study of functional-morphological changes of gastric secretion and salivary glands activity will allow to assess the condition of reserve capabilities of the protection factors of the mucous membrane of the stomach and to determine the risk groups of patients with the precancerous condition

Effect of Al2O3 and CaF2 additives on the viscosity of conventional cryolite melts

The viscosity of cryolite melts of conventional composition NaF–AlF3–CaF2–Al2O3 was studied by rotational viscometry using the FRS 1600 high-temperature rheometer. The cryolite ratio of the NaF–AlF3 melt was 2.1, 2.3, and 2.5; the Al2O3 content varied from 2 to 6.6, and CaF2 – from 0 to 8 wt%. The measurements were carried out in the temperature range from liquidus to 1200 °C. The conditions for the laminar flow of the investigated melts were determined, based on the measurements of the cryolite melts viscosity as a function of the shear rate at a constant temperature. A shear rate of 12 ± 1 s–1 was chosen for studying the viscosity temperature dependence for all samples. The viscosity temperature dependence of cryolite melts is described by a linear equation. The temperature coefficient b in this equation has negative values and varies in the range of (–0.01)–(–0.06) mPa·s/deg. It was found that the viscosity of cryolite melts of conventional composition in the range of operating temperatures of aluminum electrolysis (950–970 °C) varies from 2.5 to 3.7 mPa·s (depending on the composition and temperature). The viscosity of cryolite-alumina melts increases with the rise of alumina content: 1 wt% Al2O3 increases the viscosity, on average, by 1%. However, the influence of CaF2 is more significant: the addition of 1 wt% CaF2 leads to an increase in viscosity by 3%. A decrease in the CR of the melt by 0.1 (in the range of 2.1–2.5) leads to a decrease in the viscosity of cryolite melts by 2.3%. A viscosity regression equation for the cryolite melts of conventional composition as a function of several independent parameters (temperature, CR, CaF2 and Al2O3 content) is obtained by the multivariable approximation of experimental data. The equation satisfactorily (within 1.5%) describes the viscosity of conventional industrial electrolytes and can be used for estimation of their viscosity

Borated graphite cathodes for low-temperature aluminum electrolysis

Electrochemical boriding of the graphite plates in the potassium cryolite based electrolytes was studied. The boriding were carried out in a cell with vertical electrodes. The procedure included 2 stages: 1) electrolysis in the KF–AlF3–KBF4 melt (CR=1.3) at low current density (0.01–0.02 A/cm2), required for the boron reduction, at 700 and 750 °C; 2) electrolysis in the KF–AlF3–Al2O3 melt at higher current density (0.2 A/cm2), required for the aluminum reduction. The optimal conditions of electrodeposition for obtaining the borated wettable cathodes were determined. According to the SEM data, a continuous AlB2 layer with a thickness of 7–10 μm was formed on the graphite surface. The borated graphite was tested as a wetted cathode during the low-temperature aluminum electrolysis. Prolonged electrolysis in a vertical cell with the graphite anode and the borated graphite cathode was carried out in the KF–NaF(10 wt.%)–AlF3–Al2O3 electrolyte (CR=1.5) at 830 °C. After 100 h of electrolysis, the thickness of the AlB2 layer on the graphite surface was 5 μm, while the cathode surface was completely wetted with aluminum. Thus, we demonstrated the feasibility of using the borated graphite cathode as a wettable dripping cathode in the low-temperature aluminum electrolysis in the vertical cell

ДАТЧИК ДЛЯ ВИМІРУ ШВИДКОСТІ ГАЗОВОГО ПОТОКУ

The construction of sensor is worked out for measuring of speed of gas stream on the overfall of pressure. She is presented by two tubes-transceivers of static pressure, the ends of that from one side divide a gas-proof plane. The construction of sensor allows to control the difference of pressure in gas pipe with the different geometrical forms of transversal cut at high operating reliability of work in the conditions of both air and dust-laden air-gas stream. Methodology of determination of aerodynamic parameters and checking system offer. Instrumental measuring certainly: parameters of work of basic elements of gas highway vacuum "sintermachine-fan", their influence on the basic technical indexes of process of agglomeration.The analysis of quantitative descriptions of the productivity of gas highway of sintering machine on elements gives possibility to define the size of "harmful receivabless of air", and also places of losses. It is set that the most of gas passes through the first and last vacuum chambers. Exactly there the greatest amount of "harmful receivabless of air".Determining measuring the amount of natural gas and air, that given on gas-rings, by a calculation is an amount of smoke gas that appears, and measuring is an amount of gas that is taken from a layer, by means of sensor, there is possibility in the automatic mode to support the necessary level of dilution in the first vacuum chambers. It will do impossible the receivabless of cold air in the used for setting fire furnace, will bring down the level of harmful receivabless of air through butt-end compressions and will promote the level of useful receivabless of air through the layer of charge in middle part of sinter machine. A sensor after the technical advantages can be used in different industries of industry.Разработана конструкция датчика для измерения скорости газового потока по перепаду давления. Она представлена двумя трубками-приемниками статичного давления, концы которых с одной стороны разделены газонепроницаемой плоскостью. Конструкция датчика позволяет контролировать разницу давления в газоходах с разными геометрическими формами поперечного сечения при высокой эксплуатационной надежности работы в условиях как воздушного, так и запыленного газовоздушного потока. Предложена методика определения аэродинамических параметров и система контроля. Инструментальными измерениями определенно: параметры работы основных элементов газового тракта «агломашина-эксгаустер», их влияние на основные технические показатели процесса агломерации.Анализ количественных характеристик производительности газового тракта агломерационной машины по элементам предоставляет возможность определить величину «вредных подсосов», а также мест потерь. Установлено, что наибольшее количество газа проходит через первые и последние вакуум-камеры. Именно там наивысшее количество вредных подсосов.Определяя измерением количество природного газа и воздуха, что подаются на горелки, расчетом - количество дымового газа, и измерением - количество газа который отводится из слоя, с помощью датчика, есть возможность в автоматическом режиме поддерживать необходимый уровень разрежения в первых вакуум-камерах. Это сделает невозможным подсос холодного воздуха в зажигательный горн, снизит уровень вредных подсосов через торцевые уплотнения и повысит уровень полезных подсосов через слой шихты в средней части агломашины. Датчик за своими техническими преимуществами может быть использован в разных отраслях промышленности.Розроблено конструкцію датчика для виміру швидкості газового потоку по перепаду тиску. Вона представлена двома трубками-приймачами статичного тиску, кінці яких з одного боку розділені газонепроникною площиною.Конструкція датчика дозволяє контролювати різницю тиску в газоходах з різними геометричними формами поперечного перерізу, при високій експлуатаційній надійності роботи в умовах як повітряного, так і запиленого газоповітряного потоку.Запропоновано методику визначення аеродинамічних параметрів та систему контролю. Інструментальними вимірами визначено: параметри роботи основних елементів газового тракту «агломашина–ексгаустер», їх вплив на основні технічні показники процесу агломерації.Аналіз кількісних характеристик продуктивності газового тракту агломераційної машини по елементах надає можливість визначити величину «шкідливих підсмоктувань», а також місць втрат. Встановлено, що найбільша кількість газу проходить через перші і останні вакуум-камери. Саме там найвища кількість шкідливих підсмоктувань.Визначаючи вимірюванням кількість природного газу і повітря, що подаються на пальники, розрахунком – кількість димового газу, що утворюється, та вимірюванням – кількість газу, що відводиться з шару, за допомогою датчика, є можливість в автоматичному режимі підтримувати необхідний рівень розрідження в перших вакуум-камерах. Це унеможливить підсмоктування холодного повітря в запалювальний горн, знизить рівень шкідливих підсмоктувань через торцеві ущільнення, та підвищить рівень корисних підсмоктувань через шар шихти в середній частині агломашини.Датчик за своїми технічними перевагами може бути використаний в різних галузях промисловості