Research of Mechanical Treatment Influence on Rheological Properties of Coal-Water Fuel Based on Low-Grade 3B Coal

Experimental study of mechanical treatment effect of rotary flow modulation device on coal-water fuel rheological properties were conducted. The slurry was prepared on the basis of low-grade 3B coal from Balakhtinskoe deposit

Research of wood waste concentration influence on composite fuel energy characteristics based on low-grade 2b coal from "Borodinskoe" deposit

A pyrolysis process of different coal samples into three different types of oxidizing medium (argon, air and steam) were studied by means of thermogravimetry. Two coal types with different metamorphism degree (lignite and bituminous coal) were used. The experimental procedure was carried out in non-isothermal conditions in temperature range from 373 K to 1273 K with 20 K/min heating rate. Purge gas consisted of argon and oxidizer with volumetric ratio 1:24 and had 250 ml/min flow rate. Kinetic parameters were defined by fitting procedure using Arrhenius-type equation with the first order reaction rate on conversion distribution function. The ignition and burnout indexes were calculated to evaluate sample reactivity at different oxidizing mediums. The highest reactivity values in same atmosphere were obtained for lignite because of higher particle special surface area. For same samples the higher reactivity was obtained in steam medium. The conclusion about some kind of synergy between carbon oxidation and pyrolysis could be made

To the selection of shock absorber elements of the artificial foot

Introduction. Walking on a prosthesis of the lower limb is accompanied by a shock load on the artificial foot, which provokes discomfort when using the product and pain in the stump, increases the risk of trauma to the skin and the formation of arthrosis of the joints of the lower limb. These negative consequences can be reduced by the use of prosthetic modules with shock-absorbing properties. Usually, the artificial foot plays the role of a shock absorber in the prosthesis.Aim – substantiation of the choice of material for the shock-absorbing module of the artificial foot.Materials and methods. Bench tests of leaf springs made of steel, carbon and titanium alloy of different thicknesses were carried out by registering changes in their geometric characteristics under a dosed load, as well as full-scale tests of experimental artificial feet with such springs used as a load absorber. The functionality of the feet was determined by the subjective assessment of the comfort of the prosthesis by the patient and the result of the analysis of pressure dynamics under the feet. Results. The results of bench tests showed that leaf springs made of steel 2 mm thick, titanium alloy 3 mm and carbon fiber (carbon) 5.7 mm are unsuitable for use as a shock absorber in the foot of the prosthesis in terms of deflection in the longitudinal and transverse directions under load, in contrast to springs made of 3 mm steel and 4 mm titanium alloy. Field tests of experimental feet with shock-absorbing modules made of steel 3 mm thick and titanium alloy 4 mm showed their suitability for use as part of a prosthesis, which was confirmed by a positive assessment of their comfort by patients, as well as an increase in the symmetry coefficient of the duration of the roll over the artificial and intact feet when walking with experimental foot design compared to industrially manufactured.Discussion. The 4mm titanium alloy leaf spring outperforms the 3mm steel spring in terms of buckling under load, but biomechanical studies have not shown a clear preference for the experimental foot with one of these materials over the other. At the same time, each of them turned out to be more functional than the commercially manufactured foot chosen for the study. But the high corrosion resistance and low specific gravity of the titanium alloy, higher mechanical strength per unit mass compared to steel, give advantages to this material for the manufacture of shock-absorbing modules in atypical prostheses. The choice of the thickness of the elastic element can and should be calculated taking into account the weight of the disabled person.Conclusion. The manufacture of elastic elements from titanium alloys is promising when used in artificial feet for atypical prostheses that require high corrosion resistance and mechanical strength with a small mass of the product. A positive factor in the use of titanium alloys for the manufacture of foot shock absorbers in the form of leaf springs is the simplicity and low cost of the design

ВЕРОЯТНОСТНО-СТАТИСТИЧЕСКАЯ ОЦЕНКА ШЕРОХОВАТОСТИ ПОВЕРХНОСТИ ЭЛЕКТРОИМПУЛЬСНО ПОЛИРОВАННЫХ ДЕТАЛЕЙ

The paper presents methodology and results of investigations pertaining to profilograms of specimen surfaces being polished using electric pulse method and being made of steel 10 и 20Х13 with the help of correlative transformation. It has been established that in the process of polishing topography formation is initiated due to simultaneous surfacing of micro- and sub-micro-irregularities with equal probability and equal intensity. The obtained mechanism for topography formation is justified by the fact that break-down of gas-vapor shell takes place with equal probability as on the micro-profile top so in its cavities on the polished surface in the zones of accidental  non-homogeneity of electric field.Приведены методика и результаты исследования профилограмм электроимпульсно полированных поверхностей образцов из сталей 10 и 20Х13 с помощью корреляционного преобразования. Установлено, что в процессе полирования формирование топографии поверхности происходит за счет одновременного с равной вероятностью и равной интенсивностью сглаживания микро- и субмикронеровностей поверхности. Выявленный механизм формирования топографии обусловлен тем, что пробой парогазовой оболочки происходит с равной вероятностью как на вершинах, так и во впадинах микропрофиля обрабатываемой поверхности в областях случайных неоднородностей электрического поля.

Laboratory experiments on the interaction of a buoyant coastal current with a canyon : application to the East Greenland Current

Author Posting. © American Meteorological Society, 2009. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Physical Oceanography 39 (2009): 1258-1271, doi:10.1175/2008JPO4028.1.This paper presents a set of laboratory experiments focused on how a buoyant coastal current flowing over a sloping bottom interacts with a canyon and what controls the separation, if any, of the current from the upstream canyon bend. The results show that the separation of a buoyant coastal current depends on the current width W relative to the radius of curvature of the bathymetry ρc. The flow moved across the mouth of the canyon (i.e., separated) for W/ρc > 1, in agreement with previous results. The present study extends previous work by examining both slope-controlled and surface-trapped currents, and using a geometry specific to investigating buoyant current–canyon interaction. The authors find that, although bottom friction is important in setting the position of the buoyant front, the separation process driven by the inertia of the flow could overcome even the strongest bathymetric influence. Application of the laboratory results to the East Greenland Current (EGC), an Arctic-origin buoyant current that is observed to flow in two branches south of Denmark Strait, suggests that the path of the EGC is influenced by the large canyons cutting across the shelf, as the range of W/ρc in the ocean spans those observed in the laboratory. What causes the formation of a two-branched EGC structure downstream of the Kangerdlugssuaq Canyon (68°N, 32°W) is still unclear, but potential mechanisms are discussed.This work was partially funded by NSF Grant OCE-0450658. DS also received support from the Academic Programs Office of the Woods Hole Oceanographic Institution, while CC had partial support from NSF OCE-0350891

The East Greenland Coastal Current : structure, variability, and forcing

Author Posting. © Elsevier B.V. , 2008. This is the author's version of the work. It is posted here by permission of Elsevier B.V. for personal use, not for redistribution. The definitive version was published in Progress In Oceanography 78 (2008): 58-77, doi:10.1016/j.pocean.2007.09.006.The subtidal circulation of the southeast Greenland shelf is described using a set of high-resolution hydrographic and velocity transects occupied in summer 2004. The main feature is the East Greenland Coastal Current (EGCC), a low-salinity, high-velocity jet with a wedge-shaped hydrographic structure characteristic of other surface buoyancydriven currents. The EGCC was observed along the entire Greenland shelf south of Denmark Strait, while the transect north of the strait showed only a weak shelf flow. This observation, in conjunction with water mass considerations and other supporting evidence, suggests that the EGCC is an inner branch of the East Greenland Current (EGC) that forms south of Denmark Strait. It is argued that bathymetric steering is the most likely reason why the EGC apparently bifurcates at this location. Repeat sections occupied at Cape Farewell between 1997 and 2004 show that the alongshelf wind stress can have a strong influence on the structure and strength of the EGCC and EGC on timescales of 2-3 days. Accounting for the wind-induced effects, the volume transport of the combined EGCC/EGC system is roughly constant (~2 Sv) over the study domain, from 68°N to Cape Farewell near 60°N. The corresponding freshwater transport increases by roughly 60% over this distance (59 to 96 mSv, referenced to a salinity of 34.8). This trend is consistent with a simple freshwater budget of the EGCC/EGC system that accounts for meltwater runoff, melting sea-ice and icebergs, and net precipitation minus evaporation.This work was funded by the National Science Foundation grant OCE-0450658. DS was also partially supported by the Woods Hole Oceanographic Institution Academic Programs Office

ВЛИЯНИЕ ТЕХНОЛОГИЧЕСКИХ ПРИМЕСЕЙ НА ВОЛЬТ-АМПЕРНЫЕ ХАРАКТЕРИСТИКИ БИПОЛЯРНОГО n–p–n-ТРАНЗИСТОРА

Contamination of the monocrystal silicon with technological impurities in the devices fabrication process exerts a considerable influence on the electro-physical characteristics of the bipolar n–p–n-transistors. Revelation of the causes of the labile reproducibility of the basic characteristics of the bipolar planar n–p–n-transistors is vital for the purpose of establishing the factors, determining reliability and stability of the operational parameters of the integrated circuits. There were investigated I–V characteristics of the various lots of the bipolar n–p–n-transistors, fabricated under the epitaxialplanar technology as per the similar process charts with the identical used technological materials, however, at different times. It is established that the electro-physical characteristics of the bipolar n–p–n-transistors substantially depend on the contents of the technological impurities in the substrate material. Availability of the high concentration of the generation-recombination centers, related to the metallic impurities, results both in increase of the reverse current of the collector – base junction of the transistors and the significant reduction of the breakdown voltage of the collector junction. The most probable cause of deterioration of the electro-physical parameters of the bipolar n–p–n-transistors is the material contamination with the technological impurities (such, as Fe, Cl, Ca, Cu, Zn and others) during the production process of the devices fabrication. The sources of impurity may be both the components and sub-assemblies of the technological units and the materials and reagents under usage.Загрязнение монокристаллического кремния технологическими примесями в процессе изготов- ления приборов оказывает существенное влияние на электрофизические характеристики биполярных n–p–n-тран- зисторов. Выявление причин лабильной воспроизводимости основных характеристик биполярных планарных n–p–n-транзисторов является актуальным с целью установления факторов, определяющих надежность и стабильность эксплуатационных параметров интегральных микросхем. Исследованы вольт-амперные характеристики различных партий биполярных n–p–n-транзисторов, изготовленных по эпитаксиально-планарной технологии по аналогичным технологическим маршрутам, при идентичных используемых технологических материалах, однако в различное время. Установлено, что электрофизические характеристики биполярных n–p–n-транзисторов существенным образом зависят от содержания технологических примесей в материале подложки. Наличие высокой концентрации генерационно-рекомбинационных центров, связанных с металлическими примесями, приводит как к увеличению обратного тока через переход коллектор–база транзисторов, так и к существенному снижению напряжения пробоя коллек- торного перехода. Наиболее вероятной причиной ухудшения электрофизических параметров биполярных n–p–nтранзисторов является загрязнение материала технологическими примесями (такими, как Fe, Cl, Ca, Cu, Zn и др.) во время производственного процесса изготовления приборов. Источниками загрязнений могут служить как детали и узлы технологических установок, так и используемые материалы и реактивы