Исследование эффективности сглаживающих реакторов РЖФА‑6500

DC traction power supply systems have become widespread in several countries. Electricity consumption by traction power supply systems has pronounced seasonal and daily peaks. The peak nature of consumption leads to additional heating of live parts since time constants of transient thermal and electrophysical processes differ by several orders of magnitude, therefore, reducing ohmic resistance of electrical equipment, other things being equal, is an extremely important task.Within the framework of solving the problem of increasing energy efficiency of equipment of DC traction substations, smoothing reactor filter devices with an armoured radial-cylindrical magnetic core with low ohmic resistance, named RZhFA‑6500, were developed and manufactured.In 2018, two blocks of RZhFA‑6500 smoothing reactors were put into pilot operation at one of the most heavily loaded sections of DC electrified railways, providing traffic of trains weighing up to 9000 tons and traffic volume of about a hundred pairs of trains per day.To determine comparative indicators of energy efficiency, data on consumption of electric power for traction of trains for the compared periods before and after introduction of smoothing reactors of a new type were requested. The data received from JSC Russian Railways contained information on the traffic volume, type of rolling stock, and weight of the transported goods in accordance with the executed traffic schedule through section under consideration. The resulting set of data served as the basis for development of a multivariate methodology for assessing energy efficiency of reactors of a new type, as well as their contribution to efficiency of train operation over the considered comparative time interval. Since efficiency of power equipment also depends on the ambient temperature, the average integral parameter of average daily temperature was introduced into the calculation methodology, which, as it turned out, during processing initial data and construction of characteristic graphical dependencies, has a comparative difference of less than one percent for the same monitored periods.Accurate quantitative accounting of the data on consumption of electrical energy provided for traction of trains, exchange of reactive energy with the supply network, volume of transportation allowed to obtain an objective comparison of contribution of smoothing reactors of a new type to increasing efficiency of train operation and reducing consumption of electrical energy for traction of trains.Системы тягового электроснабжения постоянного тока получили своё распространение в ряде стран. Потребление электроэнергии системами тягового электроснабжения имеет явно выраженные сезонные и суточные пики. Пиковый характер потребления приводит к дополнительному нагреву токоведущих частей в связи с тем, что постоянные времени переходных тепловых и электрофизических процессов различаются на несколько порядков, поэтому снижение омического сопротивления электрооборудования при прочих равных условиях является чрезвычайно важной задачей.В рамках решения проблемы повышения энергоэффективности оборудования тяговых подстанций постоянного тока были разработаны и изготовлены сглаживающие реакторы фильтр-устройства с бронестержневой радиально-цилиндрической магнитной системой с пониженным омическим сопротивлением, получившие название РЖФА‑6500.В 2018 году два блока реакторов РЖФА‑6500 введены в опытно-промышленную эксплуатацию на одном из самых грузонапряжённых участков магистральных железных дорог постоянного тока, обеспечивающем пропуск поездов массой до 9000 тонн с размерами движения порядка ста пар поездов в сутки.В целях определения сравнительных показателей энергоэффективности были запрошены данные по расходу электрической энергии на тягу поездов за аналогичные периоды до внедрения сглаживающих реакторов нового типа и после. От ОАО «РЖД» получены данные относительно размеров движения, типа подвижного состава и массы перевезённых грузов, согласно исполненному графику движения поездов на рассматриваемом участке. Полученная совокупность данных послужила основой для разработки многофакторной методики оценки энергоэффективности реакторов нового типа, а также их вклада в эффективность поездной работы на рассматриваемом сравнительном интервале времени. Ввиду того, что эффективность энергосилового оборудования зависит также от температуры окружающей среды, в методику расчёта был введён среднеинтегральный параметр среднесуточной температуры, который, как оказалось в ходе обработки исходных данных и представления их в виде характерных графических зависимостей, имеет сравнительное отличие – менее одного процента за аналогичные периоды наблюдений.Точный количественный учёт расхода электрической энергии на тягу поездов, обмена реактивной энергии с питающей сетью, объёмов выполненных перевозок позволил провести объективное сравнение вклада сглаживающих реакторов нового типа в повышение эффективности поездной работы и снижение расходов электрической энергии на тягу поездов

The relationship between auroral hiss at high altitudes over the polar caps and the substorm dynamics of aurora

Strong variations of intensity and cutoff frequency of the auroral hiss were observed by INTERBALL-2 and POLAR satellites at high altitudes, poleward from the auroral oval. The hiss intensifications are correlated with the auroral activations during substorms and/or pseudo-breakups. The low cutoff frequency of auroral hiss increases with the distance between the aurora and the satellite footprint. Multicomponent wave measurements of the hiss emissions on board the POLAR spacecraft show that the horizontal component of the Poynting flux of auroral hiss changes its direction in good accordance with longitudinal displacements of the bright auroras. The vertical component of the Poynting flux is directed upward from the aurora region, indicating that hiss could be generated by upgoing electron beams. This relationship between hiss and the aurora dynamics means that the upgoing electron beams are closely related to downgoing electron beams which produce the aurora. During the auroral activations the upgoing and downgoing beams move and change their intensities simultaneously.<br><br> <b>Keywords.</b> Magnetospheric physics (Auroral phenomena; Plasma waves and instabilities; Storms and substorms

Stability and Electronic Properties of TiO2 Nanostructures With and Without B and N Doping

We address one of the main challenges to TiO2-photocatalysis, namely band gap narrowing, by combining nanostructural changes with doping. With this aim we compare TiO2's electronic properties for small 0D clusters, 1D nanorods and nanotubes, 2D layers, and 3D surface and bulk phases using different approximations within density functional theory and GW calculations. In particular, we propose very small (R < 0.5 nm) but surprisingly stable nanotubes with promising properties. The nanotubes are initially formed from TiO2 layers with the PtO2 structure, with the smallest (2,2) nanotube relaxing to a rutile nanorod structure. We find that quantum confinement effects - as expected - generally lead to a widening of the energy gap. However, substitutional doping with boron or nitrogen is found to give rise to (meta-)stable structures and the introduction of dopant and mid-gap states which effectively reduce the band gap. Boron is seen to always give rise to n-type doping while depending on the local bonding geometry, nitrogen may give rise to n-type or p-type doping. For under coordinated TiO2 surface structures found in clusters, nanorods, nanotubes, layers and surfaces nitrogen gives rise to acceptor states while for larger clusters and bulk structures donor states are introduced

Mutual Validation of GNSS Height Measurements and High-precision Geometric-astronomical Leveling

The method of geometric-astronomical leveling is presented as a suited technique for the validation of GNSS (Global Navigation Satellite System) heights. In geometric-astronomical leveling, the ellipsoidal height differences are obtained by combining conventional spirit leveling and astronomical leveling. Astronomical leveling with recently developed digital zenith camera systems is capable of providing the geometry of equipotential surfaces of the gravity field accurate to a few 0.1 mm per km. This is comparable to the accuracy of spirit leveling. Consequently, geometric-astronomical leveling yields accurate ellipsoidal height differences that may serve as an independent check on GNSS height measurements at local scales. A test was performed in a local geodetic network near Hanover. GPS observations were simultaneously carried out at five stations over a time span of 48 h and processed considering state-of-the-art techniques and sophisticated new approaches to reduce station-dependent errors. The comparison of GPS height differences with those from geometric-astronomical leveling shows a promising agreement of some millimeters. The experiment indicates the currently achievable accuracy level of GPS height measurements and demonstrates the practical applicability of the proposed approach for the validation of GNSS height measurements as well as the evaluation of GNSS height processing strategies

Regulation of peripheral blood flow in Complex Regional Pain Syndrome: clinical implication for symptomatic relief and pain management

Background. During the chronic stage of Complex Regional Pain Syndrome (CRPS), impaired microcirculation is related to increased vasoconstriction, tissue hypoxia, and metabolic tissue acidosis in the affected limb. Several mechanisms may be responsible for the ischemia and pain in chronic cold CPRS. Discussion. The diminished blood flow may be caused by either sympathetic dysfunction, hypersensitivity to circulating catecholamines, or endothelial dysfunction. The pain may be of neuropathic, inflammatory, nociceptive, or functional nature, or of mixed origin. Summary. The origin of the pain should be the basis of the symptomatic therapy. Since the difference in temperature between both hands fluctuates over time in cold CRPS, when in doubt, the clinician should prioritize the patient's report of a persistent cold extremity over clinical tests that show no difference. Future research should focus on developing easily applied methods for clinical use to differentiate between central and peripheral blood flow regulation disorders in individual patients

Natural masers and two point wave studies in the forthcoming RESONANCE project

The only natural masers that can be studied experimentally in-situ are magnetospheric masers. Concept of the magnetospheric cyclotron maser has been derived from the self-consistent theory of the radiation belts. In this natural maser energetic charged particles serve as an active substance, and an electro-dynamic system is formed by the magnetic flux tube filled with the background plasma and corresponding ionospheric footprint. The forthcoming RESONANCE project will provide the opportunity for multipoint measurements of waves and plasma processes involved in magnetospheric masers phenomenon. It will allow detailed in-situ studies of resonant wave-particle interactions that excite pearl and whistler waves in the inner magnetosphere. Methods of linear and nonlinear processes identification that quantify the dynamics of plasma waves generated by magnetopsheric masers are considered. The proposed technique allows differentiating between the linear wave-particle interaction and nonlinear processes of energy transfer in plasma turbulence

High-accuracy analysis of nanoscale semiconductor layers using beam-exit Ar-ion polishing and scanning probe microscopy

A novel method of sample cross-sectioning, beam-exit Ar-ion cross-sectional polishing, has been combined with scanning probe microscopy to study thin AlxGa1-xAs/GaAs layers. Additional contrast enhancement via a citric acid/hydrogen peroxide etch allows us to report the observation of layers as thin as 1 nm. Layer thickness measurements agree with transmission electron microscopy (TEM) data to 0.1 ± 0.2 nm, making this a very promising low-cost method for nanoscale analysis of semiconductor heterostructures

AKR bursts and substorm field line excitation

International audienceA new manifestation of the Auroral Kilometric Radiation is put in evidence through the observations of the POLRAD wave experiment of the INTERBALL mission, the Wide Band Bursts of the AKR, or WBB AKR. It consists in bursts of radiation with a very broad bandwidth, typically 100 - 800 kHz. The whole frequency range is excited at once or in less than a few minutes. This corresponds to the excitation of long segments of auroral field lines in a time often less than one minute. The sources of the emission are stretched along the field lines between altitudes ranging from 2000 to 20000 km. The relationship of these bursts to the development of auroral bulges, in the UV spectral range, is shown by comparison of the POLRAD wave observations and those of the UV imager of the POLAR mission. It is shown that these bursts are generated during fast expansion of the auroral bulge. An accurate timing of the burst events is made with the time evolution of the frequency integrated wave energy flux. It shows that the bursts have a rise time of a few minutes, which is followed by an exponential relaxation with a characteristic time of a few tens of minutes. The source of the bursts first expands along the field lines then it shrinks during the relaxation phase. The bursts are triggered a few minutes before the maximum intensity of the UV auroral bulge. It is also shown that the bursts actually consist of a large number of individual broad bandwidth elements, each lasting for less than a few seconds