Interaction of electric and acoustic vibrations in combustion

The results of experimental studies of the interaction of electrical discharges in the acoustic oscillations in the combustion of isobutane are presented in the article. Electric discharges were created using a pulsed high voltage source at specified intervals. The purpose of the study was to determine the feasibility of using electrical pulse action to control combustion. The study was conducted on the specifically designed pattern of the combustion chamber with a swirl burner in the frequency range from 100 Hz to 1400 Hz. The study found that the method of periodic pulsed electrical influences can be used to control the combustion in the combustion chamber model. There is a steady increase in the amplitude of the oscillations in the combustion chamber model. Effects due to the mechanism of interaction of acoustic waves and oscillations heat release from the combustion zone. Estimated physical mechanism is a periodic change in the concentration of ions in the interaction of the combustion zone with the electric field of high potential. The proposed control method is advantageous in terms of energy costs

Plasma technologies application for building materials surface modification

© Published under licence by IOP Publishing Ltd.Low-temperature plasma modification of LiYF4 crystal surface in Helium atmosphere caused microhardness decreasing and increasing of roughness of crystal surface. The change of microhardness and morphology is a possible result of Fluorine outgoing from material structure due to heating of surface and plasma chemical reactions and ingoing of Oxygen. As a result of exchange and diffusion processes crystal surface structure become more crumbly, its morphology and mechanical properties change

Yb-Yb correlations and crystal-field effects in the Kondo insulator YbB12 and its solid solutions

We have studied the effect of Lu substitution on the spin dynamics of the Kondo insulator YbB12 to clarify the origin of the spin-gap response previously observed at low temperature in this material. Inelastic neutron spectra have been measured in Yb1-xLuxB12 compounds for four Lu concentrations x = 0, 0.25, 0.90 and 1.0. The data indicate that the disruption of coherence on the Yb sublattice primarily affects the narrow peak structure occurring near 15-20 meV in pure YbB12, whereas the spin gap and the broad magnetic signal around 38 meV remain almost unaffected. It is inferred that the latter features reflect mainly local, single-site processes, and may be reminiscent of the inelastic magnetic response reported for mixed-valence intermetallic compounds. On the other hand, the lower component at 15 meV is most likely due to dynamic short-range magnetic correlations. The crystal-field splitting in YbB12 estimated from the Er3+ transitions measured in a Yb0.9Er0.1B12 sample, has the same order of magnitude as other relevant energy scales of the system and is thus likely to play a role in the form of the magnetic spectral response.Comment: 16 pages in pdf format, 9 figures. v. 2: coauthor list updated; extra details given in section 3.2 (pp. 6-7); one reference added; fig. 5 axis label change

Collective magnetic excitations in mixed-valence Sm0.83Y0.17S

The magnetic spectral response of black-phase mixed-valence Sm0.83Y0.17S has been measured by inelastic neutron scattering on a single crystal. Two magnetic peaks are observed in the energy range of the Sm2+ spin-orbit transition (25-40 meV). Both of them exhibit significant dispersion along the three main symmetry directions, reminiscent of the spin-orbit exciton branch found in pure divalent SmS. The results can be reproduced by a simple phenomenological model accounting for the existence of sizeable Sm-Sm exchange interactions, and a microscopic mechanism is proposed on the basis of the "local-bound-state" theory developed previously for SmB6.Comment: 6 pages in pdf format, 3 figures, submitted to Phys. Rev.

The role of retreatment in the management of recurrent/progressive brain metastases: a systematic review and evidence-based clinical practice guideline

QUESTION: What evidence is available regarding the use of whole brain radiation therapy (WBRT), stereotactic radiosurgery (SRS), surgical resection or chemotherapy for the treatment of recurrent/progressive brain metastases? TARGET POPULATION: This recommendation applies to adults with recurrent/progressive brain metastases who have previously been treated with WBRT, surgical resection and/or radiosurgery. Recurrent/progressive brain metastases are defined as metastases that recur/progress anywhere in the brain (original and/or non-original sites) after initial therapy. RECOMMENDATION: Level 3 Since there is insufficient evidence to make definitive treatment recommendations in patients with recurrent/progressive brain metastases, treatment should be individualized based on a patient\u27s functional status, extent of disease, volume/number of metastases, recurrence or progression at original versus non-original site, previous treatment and type of primary cancer, and enrollment in clinical trials is encouraged. In this context, the following can be recommended depending on a patient\u27s specific condition: no further treatment (supportive care), re-irradiation (either WBRT and/or SRS), surgical excision or, to a lesser extent, chemotherapy. Question If WBRT is used in the setting of recurrent/progressive brain metastases, what impact does tumor histopathology have on treatment outcomes? No studies were identified that met the eligibility criteria for this question

Development of methods for the preparation of radiopure ⁸²Se sources for the SuperNEMO neutrinoless double-beta decay experiment

A radiochemical method for producing 82Se sources with an ultra-low level of contamination of natural radionuclides (40K, decay products of 232Th and 238U) has been developed based on cation-exchange chromatographic purification with reverse removal of impurities. It includes chromatographic separation (purification), reduction, conditioning (which includes decantation, centrifugation, washing, grinding, and drying), and 82Se foil production. The conditioning stage, during which highly dispersed elemental selenium is obtained by the reduction of purified selenious acid (H2SeO3) with sulfur dioxide (SO2) represents the crucial step in the preparation of radiopure 82Se samples. The natural selenium (600 g) was first produced in this procedure in order to refine the method. The technique developed was then used to produce 2.5 kg of radiopure enriched selenium (82Se). The produced 82Se samples were wrapped in polyethylene (12 μm thick) and radionuclides present in the sample were analyzed with the BiPo-3 detector. The radiopurity of the plastic materials (chromatographic column material and polypropylene chemical vessels), which were used at all stages, was determined by instrumental neutron activation analysis. The radiopurity of the 82Se foils was checked by measurements with the BiPo-3 spectrometer, which confirmed the high purity of the final product. The measured contamination level for 208Tl was 8-54 μBq/kg, and for 214Bi the detection limit of 600 μBq/kg has been reached.</p

Interaction of electric and acoustic vibrations in combustion

The results of experimental studies of the interaction of electrical discharges in the acoustic oscillations in the combustion of isobutane are presented in the article. Electric discharges were created using a pulsed high voltage source at specified intervals. The purpose of the study was to determine the feasibility of using electrical pulse action to control combustion. The study was conducted on the specifically designed pattern of the combustion chamber with a swirl burner in the frequency range from 100 Hz to 1400 Hz. The study found that the method of periodic pulsed electrical influences can be used to control the combustion in the combustion chamber model. There is a steady increase in the amplitude of the oscillations in the combustion chamber model. Effects due to the mechanism of interaction of acoustic waves and oscillations heat release from the combustion zone. Estimated physical mechanism is a periodic change in the concentration of ions in the interaction of the combustion zone with the electric field of high potential. The proposed control method is advantageous in terms of energy costs

Interaction of electric and acoustic vibrations in combustion

The results of experimental studies of the interaction of electrical discharges in the acoustic oscillations in the combustion of isobutane are presented in the article. Electric discharges were created using a pulsed high voltage source at specified intervals. The purpose of the study was to determine the feasibility of using electrical pulse action to control combustion. The study was conducted on the specifically designed pattern of the combustion chamber with a swirl burner in the frequency range from 100 Hz to 1400 Hz. The study found that the method of periodic pulsed electrical influences can be used to control the combustion in the combustion chamber model. There is a steady increase in the amplitude of the oscillations in the combustion chamber model. Effects due to the mechanism of interaction of acoustic waves and oscillations heat release from the combustion zone. Estimated physical mechanism is a periodic change in the concentration of ions in the interaction of the combustion zone with the electric field of high potential. The proposed control method is advantageous in terms of energy costs

Interaction of electric and acoustic vibrations in combustion

The results of experimental studies of the interaction of electrical discharges in the acoustic oscillations in the combustion of isobutane are presented in the article. Electric discharges were created using a pulsed high voltage source at specified intervals. The purpose of the study was to determine the feasibility of using electrical pulse action to control combustion. The study was conducted on the specifically designed pattern of the combustion chamber with a swirl burner in the frequency range from 100 Hz to 1400 Hz. The study found that the method of periodic pulsed electrical influences can be used to control the combustion in the combustion chamber model. There is a steady increase in the amplitude of the oscillations in the combustion chamber model. Effects due to the mechanism of interaction of acoustic waves and oscillations heat release from the combustion zone. Estimated physical mechanism is a periodic change in the concentration of ions in the interaction of the combustion zone with the electric field of high potential. The proposed control method is advantageous in terms of energy costs