Research of a dual-frequency power supply system for induction crucible furnaces for melting ferrous and non-ferrous metals

The article describes the power supply system of induction furnace based on a semiconductor converter, in which it is possible to work simultaneously in the exciting mode of low-frequency currents and frequencies three times higher when switching the compensation circuit of the furnace inductor at different stages of metal melting. Calculations of electromagnetic processes have shown the advisability of operating the power supply system in the mode of tripling the current frequency at the stage of heating and melting of the metal, but in the mode of low frequency - at the stage of technological processing of the melt. The ratio between the parameters of the furnace power supply in various operating modes are established. © Published under licence by IOP Publishing Ltd

Эффективность цитокардиопротекции у больных с умеренно выраженной постинфарктной дисфункцией левого желудочка: результаты рандомизированного исследования триметазидина и атенолола

With the purpose of research of clinical efficiency of trimetazidine and atenolol and their influence on morfofunctional parameteres of left ventricle 36 men who have transferred a myocardial infarction are inspected. Patients were randomly divided into 2 groups. Clinical status and function state of left ventricle (by echocardiography) was assessed before and after 4-week therapy with trimetazidine or atenolol. Atenolol and trimetazidine have shown in our study identical clinical efficiency. However while atenolol is statistically significant reduced systolic arterial pressure and heart rate, thickness of posterior wall of left ventricle and corrects diastolic function, trimetazidine had no such activity. Treatment with trimetazidine promoted improvement of local contractility of left ventricle.С целью исследования клинической эффективности триметазидина и атенолола и их влияния на морфофункциональное состояние левого желудочка обследованы 36 мужчин, перенесших инфаркт миокарда. Пациентов путем рандомизации разделили на 2 группы. Клинический статус и функциональное состояние левого желудочка (эхокардиографически) оценивали до и после 4-недельной терапии триметазидином или атенололом. Атенолол и триметазидин продемонстрировали в нашем исследовании одинаковую клиническую эффективность. Однако в то время как атенолол статистически значимо снижал систолическое артериальное давление, частоту сердечных сокращений, толщину задней стенки левого желудочка и улучшал диастолическую функцию, триметазидин не обладал такой активностью. Лечение триметазидином способствовало улучшению локальной сократимости левого желудочка

DUAL FREQUENCY INDUCTION MELTING OF METAL

В работе приведена электрическая схема для двухчастотной индукционной плавки металлов и описан принцип ее работы. Разработана методика расчета индуктора печи и компенсирующего устройства. По результатам расчетов модель индукционной тигельной печи построена в программном комплексе COMSOL Multiphysics, выполнен электромагнитный, гидродинамический и тепловой расчет. По результатам расчетов можно сделать вывод, что приведенная схема позволяет увеличить КПД печи и снизить время цикла работы печи.The paper presents electrical circuit for dual-frequency induction melting of metals and describes the principle of its operation. A methodology for calculating the furnace inductor and compensating device has been developed. According to the calculation results, the model of the induction crucible furnace was built in the COMSOL Multiphysics software package, and electromagnetic, hydrodynamic, and thermal calculations were performed. Based on the calculation results, we can conclude that the above scheme allows increasing the efficiency of the furnace and reducing the cycle time of the furnace

The device for ultrasonic treatment of aluminum and magnesium melts

The paper considers the device for ultrasonic treatment of aluminum and magnesium melts. Also considers the stabilization methods of acoustic power transferred to the melt in the system with magnetostrictive transducer with feedback

Power supplies for dual-frequency induction melting of metals

The article discusses the benefits of multi frequency induction melting in the production of synthetic cast iron, structural (electric circuit) principles of dual frequency Power supplies of melting systems. The ways of electric power regulation of low frequency and high frequency components of the current in the inductor sections of furnace are demonstrated, namely power rescheduling at the metal melting stage, alloying stage and recarburizing of synthetic cast iron

Possible isotope effect on the resonance peak formation in high-Tc_c cuprates

Starting from the three-band $p-d$ Hubbard Hamiltonian we derive an effective $t-J$ model including electron-phonon interaction of quasiparticles with optical phonons. Within the effective Hamiltonian we analyze the influence of electronic correlations and electron-phonon interaction on the dynamical spin susceptibility in layered cuprates. We find a huge isotope effect on the resonance peak in the magnetic spin susceptibility, ${Im}\chi({\bf q},\omega)$, seen by inelastic neutron scattering. It results from both the electron-phonon coupling and the electronic correlation effects taken into account beyond random phase approximation(RPA) scheme. We find at optimal doping the isotope coeffiecient $\alpha_{res} \approx 0.35$ which can be further tested experimentally.Comment: revised version, new figure is added. Phys. Rev. B 69, 0945XX (2004); in pres

Measurement of Charged Pion Production Yields off the NuMI Target

The fixed-target MIPP experiment, Fermilab E907, was designed to measure the production of hadrons from the collisions of hadrons of momenta ranging from 5 to 120 GeV/c on a variety of nuclei. These data will generally improve the simulation of particle detectors and predictions of particle beam fluxes at accelerators. The spectrometer momentum resolution is between 3 and 4%, and particle identification is performed for particles ranging between 0.3 and 80 GeV/c using $dE/dx$, time-of-flight and Cherenkov radiation measurements. MIPP collected $1.42 \times10^6$ events of 120 GeV Main Injector protons striking a target used in the NuMI facility at Fermilab. The data have been analyzed and we present here charged pion yields per proton-on-target determined in bins of longitudinal and transverse momentum between 0.5 and 80 GeV/c, with combined statistical and systematic relative uncertainties between 5 and 10%.Comment: 15 pages, 13 figure

Forward Neutron Production at the Fermilab Main Injector

We have measured cross sections for forward neutron production from a variety of targets using proton beams from the Fermilab Main Injector. Measurements were performed for proton beam momenta of 58 GeV/c, 84 GeV/c, and 120 GeV/c. The cross section dependence on the atomic weight (A) of the targets was found to vary as $A^(alpha)$ where $\alpha$ is $0.46\pm0.06$ for a beam momentum of 58 GeV/c and 0.54$\pm$0.05 for 120 GeV/c. The cross sections show reasonable agreement with FLUKA and DPMJET Monte Carlos. Comparisons have also been made with the LAQGSM Monte Carlo.Comment: Accepted for publication in Physical Review D. This version incorporates small changes suggested by referee and small corrections in the neutron production cross sections predicted by FLUK