231 research outputs found
The problems of application of domestic ore raw materials in the production of ferroalloys
There is a difficult situation with ferroalloy production in Russia - production has a raw material import dependence in the presence of our own large, although not quite high-quality, in accordance with world standards, mineral resource base. As rule, domestic ferroalloy raw materials are of low quality: a low content of leading elements (manganese, chromium ores), a high content of phosphorus (manganese, niobium ores), sulfur (manganese ores). The paper gives examples of a complex of physicochemical studies and the development of a number of alternative technologies for the smelting of new ferroalloy compositions with Mn, Cr, Nb, W. The scientific studies together with the development of the technology have been carried out to study the effect of ferroalloys composition on consumer properties. Because of the fact that the chemical composition of the ores of most new deposits cannot ensure the production of standard ferroalloys. By help deep physicochemical and technological studies it is possible to create new processes and combinations of different types of ferroalloys from non-traditional domestic mineral raw materials. The alloys are not inferior in terms of technical and economic indicators of products obtained from rich imported ore materials. © Published under licence by IOP Publishing Ltd.The work was carried out according to the government contract of IMET UB RAS and according to the RFBR project No. 19-03-00451
Recent Developments of NEMO: Detection of Solar Eruptions Characteristics
The recent developments in space instrumentation for solar observations and
telemetry have caused the necessity of advanced pattern recognition tools for
the different classes of solar events. The Extreme ultraviolet Imaging
Telescope (EIT) of solar corona on-board SOHO spacecraft has uncovered a new
class of eruptive events which are often identified as signatures of Coronal
Mass Ejection (CME) initiations on solar disk. It is evident that a crucial
task is the development of an automatic detection tool of CMEs precursors. The
Novel EIT wave Machine Observing (NEMO) (http://sidc.be/nemo) code is an
operational tool that detects automatically solar eruptions using EIT image
sequences. NEMO applies techniques based on the general statistical properties
of the underlying physical mechanisms of eruptive events on the solar disc. In
this work, the most recent updates of NEMO code - that have resulted to the
increase of the recognition efficiency of solar eruptions linked to CMEs - are
presented. These updates provide calculations of the surface of the dimming
region, implement novel clustering technique for the dimmings and set new
criteria to flag the eruptive dimmings based on their complex characteristics.
The efficiency of NEMO has been increased significantly resulting to the
extraction of dimmings observed near the solar limb and to the detection of
small-scale events as well. As a consequence, the detection efficiency of CMEs
precursors and the forecasts of CMEs have been drastically improved.
Furthermore, the catalogues of solar eruptive events that can be constructed by
NEMO may include larger number of physical parameters associated to the dimming
regions.Comment: 12 Pages, 5 figures, submitted to Solar Physic
Об использовании сил сцепления колес транспортного средства, оборудованного автоматизированной системой регулирования тормозного усилия
The paper considers a method for calculation and evaluation of an automated brake proportioning system and it also describes assessment of efficiency while using cohesion forces of an automated system during vehicle braking process (MAZ 256200 taken as an example). A method for efficiency estimation of the vehicle braking equipped with an automated brake proportioning system is graphically presented in the paper. A comparable analysis has been made in order to evaluate vehicle braking efficiency in three various conditions of its wheel motion during braking process. The paper contains description of braking processes for a vehicle at its idealized braking, at braking with an operating automated system and at braking with blocked wheels. Mathematical dependences have been proposed and they make it possible to calculate a coefficient of cohesion forces used by an automated brake proportioning system on the basis of time parameters for vehicle braking process. The proposed mathematical dependences take into account design peculiarities of the automated system, i.e. a diagram of modulator arrangement on axes of the vehicle. The executed analysis for calculation accuracy of the coefficient pertaining to use of cohesion forces of the automated system with and without taking into accout rolling force resistance of the vehicle wheels has demonstrated a possibility to apply the proposed calculation methods for carrying out auto-technical expertise while investigating road-traffic accidents involving transport facilities equipped with such systems as ABS. The paper proposes a dependence for identification of a vehicle braking distance on the basis of the coefficient on use of cohesion forces by the automated brake proportioning system. The executed experimental investigations on both test and serial models of the automated brake proportioning system have allowed to justify theoretical discussions concerning application of tyre-road adhesion in the operational process of the vehicle brake proportioning system. The investigation results have shown high efficiency of the test automated brake proportioning system developed by Chair of Automobiles in the name of A. B. Hredescul at Kharkiv National Automobile and Road University under the following braking conditions: dry road surface and compacted snow cover.В статье рассмотрен метод расчета и оценки автоматизированной системы регулирования тормозного усилия, а также выполнена оценка эффективности использования силы сцепления автоматизированной системой в процессе торможения колесного транспортного средства (на примере автобуса МАЗ 256200). Графически представлен и обоснован способ оценки эффективности торможения транспортного средства, оборудованного автоматизированной системой регулирования тормозного усилия. Проведен сравнительный анализ эффективности торможения транспортного средства в трех разных условиях движения его колес при торможении. Описаны процессы торможения при идеализированном торможении, торможении при работе автоматизированной системы, а также при торможении транспортного средства с заблокированными колесами. Предложены математические зависимости, позволяющие рассчитать коэффициент использования силы сцепления автоматизированной системой регулирования тормозного усилия на основе временных параметров процесса торможения транспортного средства. Предложенные математические зависимости учитывают особенности конструкции автоматизированной системы, т. е. схему расположения модуляторов на осях колесного транспортного средства. Выполненный анализ точности расчетов коэффициента использования силы сцепления автоматизированной системой с учетом и без учета сил сопротивления качения колес транспортного средства показал возможность использования предложенных методов расчета в практике автотехнических экспертиз при расследовании дорожно-транспортных происшествий с участием транспортных средств, оборудованных такими системами, как ABS. Предложена зависимость определения тормозного пути колесного транспортного средства на основе коэффициента использования силы сцепления автоматизированной системой регулирования тормозного усилия. Выполненные экспериментальные исследования опытного и серийного образцов автоматизированной системы позволили подтвердить теоретические рассуждения в отношении использования сил сцепления в процессе работы автоматизированной системы регулирования тормозного усилия колесного транспортного средства. Результаты исследований показали высокую эффективность работы экспериментальной автоматизированной системы, разработанной на кафедре автомобилей имени А. Б. Гредескула Харьковского национального автомобильнодорожного университета, в условиях торможения транспортного средства на сухом асфальтовом и укатанном снежном покрытиях
Experimental study of direct photon emission in K- --> pi- pi0 gamma decay using ISTRA+ detector
The branching ratio in the charged-pion kinetic energy region of 55 to 90 MeV
for the direct photon emission in the K- --> pi- pi0 gamma decay has been
measured using in-flight decays detected with the ISTRA+ setup operating in the
25 GeV/c negative secondary beam of the U-70 PS. The value
Br(DE)=[0.37+-0.39(stat)+-0.10(syst)]*10^(-5) obtained from the analysis of 930
completely reconstructed events is consistent with the average value of two
stopped-kaon experiments, but it differs by 2.5 standard deviations from the
average value of three in-flight-kaon experiments. The result is also compared
with recent theoretical predictions.Comment: 13 pages, 8 figure
Transforming teacher education, an activity theory analysis
This paper explores the work of teacher education in England and Scotland. It seeks to locate this work within conflicting socio-cultural views of professional practice and academic work. Drawing on an activity theory framework that integrates the analysis of these contradictory discourses with a study of teacher educators’ practical activities, including the material artefacts that mediate the work, the paper offers a critical perspective on the social organisation of university-based teacher education. Informed by Engeström’s activity theory concept of transformation, the paper extends the discussion of contradictions in teacher education to consider the wider socio-cultural relations of the work. The findings raise important questions about the way in which teacher education work within universities is organised and the division of labour between schools and universities
Observation of the radiative kaon decay K- --> mu-pi0gammanu
Using data collected with the ISTRA+ spectrometer during the 2001 run of the
U-70 proton synchrotron in Protvino, we report the first observation of the
radiative kaon decay K- -->mu-pi0gammanu. We find Br(Kmu3g)/Br(Kmu3) for two
regions 5<Eg<30 and 30<Eg<60 MeV consistent with theoretical predictions. The
measured angular distribution asymmetry for the first region,
0.093+/-0.141, is two standard deviations away from the theoretical
prediction of 0.354. The measured asymmetry in the T-odd variable is
-0.03+/-0.13.Comment: 15 pages, 8 figurs, submitted to Yadernaya Fizik
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