201 research outputs found

    Extension of the Wu-Jing equation of state (EOS) for highly porous materials: thermoelectron based theoretical model

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    A thermodynamic equation of state (EOS) for thermoelectrons is derived which is appropriate for investigating the thermodynamic variations along isobaric paths. By using this EOS and the Wu-Jing (W-J) model, an extended Hugoniot EOS model is developed which can predict the compression behavior of highly porous materials. Theoretical relationships for the shock temperature, bulk sound velocity, and the isentrope are developed. This method has the advantage of being able to model the behavior of porous metals over the full range of applicability of pressure and porosity, whereas methods proposed in the past have been limited in their applicability.Comment: 18 pages, 1 figure, appeared at J. Appl. Phys. 92, 5924 (2002

    Equation of state SAHA-S meets stellar evolution code CESAM2k

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    We present an example of an interpolation code of the SAHA-S equation of state that has been adapted for use in the stellar evolution code CESAM2k. The aim is to provide the necessary data and numerical procedures for its implementation in a stellar code. A technical problem is the discrepancy between the sets of thermodynamic quantities provided by the SAHA-S equation of state and those necessary in the CESAM2k computations. Moreover, the independent variables in a practical equation of state (like SAHA-S) are temperature and density, whereas for modelling calculations the variables temperature and pressure are preferable. Specifically for the CESAM2k code, some additional quantities and their derivatives must be provided. To provide the bridge between the equation of state and stellar modelling, we prepare auxiliary tables of the quantities that are demanded in CESAM2k. Then we use cubic spline interpolation to provide both smoothness and a good approximation of the necessary derivatives. Using the B-form of spline representation provides us with an efficient algorithm for three-dimensional interpolation. The table of B-spline coefficients provided can be directly used during stellar model calculations together with the module of cubic spline interpolation. This implementation of the SAHA-S equation of state in the CESAM2k stellar structure and evolution code has been tested on a solar model evolved to the present. A comparison with other equations of state is briefly discussed. The choice of a regular net of mesh points for specific primary quantities in the SAHA-S equation of state, together with accurate and consistently smooth tabulated values, provides an effective algorithm of interpolation in modelling calculations. The proposed module of interpolation procedures can be easily adopted in other evolution codes.Comment: 8 pages, 5 figure

    Увеличение скорости сообщения на регулярных автобусных маршрутах

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    The article outlines the currently relevant directions for increasing the efficiency of passenger transportation by urban transport, achievable through using modern digital technologies for monitoring and controlling congestion of the road network, traffic management, and assessing reliability of thetransportation process.The objective of the study was to develop theoretical base and practical recommendations for increasing speed of traffic on regular urban bus routes during periods of high load of the urban road network using alternate roads. Theoretical studies were based on the analysis of scientific and regulatory sources, and on the system analysis of transportation processes. Experimental studies were carried out in laboratory and road conditions using mathematical modelling, methods of mathematical statistics, technical, economic and system analysis of transportation processes, analysis of passenger flows, field observations.The dependences of the flow rate of vehicles on traffic intensity, technical speed of buses on alternate roads on the flow rate of fixed-route vehicles are obtained. The economic effect resulting from implementation of recommendations was calculated for the conditions of the city of Magnitogorsk, since redirecting the buses to alternate roads during peak load periods for road network allows to increase their route speed by 7 km/h and hence to reduce the need in bus fleet by 2 units, obtaining the target economic effect.В статье обозначены актуальные направления повышения эффективности перевозок пассажиров городским транспортом за счёт использования современных цифровых технологий контроля и управления загруженностью дорожной сети, организации уличного движения, оценки надёжности перевозочного процесса.Цель работы – развитие теоретической базы и разработка практических рекомендаций  по повышению скорости сообщения на регулярных автобусных маршрутах городского  транспорта в периоды загрузки городской дорожной сети за счёт использования дополнительных дорог. Теоретические исследования выполнены на основе анализа научной и нормативно-технической литературы, системного анализа транспортных процессов. Экспериментальные исследования выполнялись в лабораторных и дорожных условиях с использованием математического моделирования, методов математической статистики, технико-экономического и системного анализа транспортных процессов, анализа пассажиропотоков, натурных наблюдений.Получены зависимости скорости потока транспортных средств от интенсивности движения, технической скорости движения автобуса по дополнительным дорогам от интенсивности потока маршрутных транспортных средств. Для условий г.  Магнитогорска рассчитан экономический эффект от практической реализации предлагаемых рекомендаций. Так, посредством перенаправления автобусов на дороги-дублёры в период пиковой загрузки дорожной сети обоснована возможность увеличения скорости сообщения на 7 км/ч, что позволит сократить потребности в автобусах на 2 единицы и получить расчётный экономический эффект

    Identity of electrons and ionization equilibrium

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    It is perhaps appropriate that, in a year marking the 90th anniversary of Meghnad Saha seminal paper (1920), new developments should call fresh attention to the problem of ionization equilibrium in gases. Ionization equilibrium is considered in the simplest "physical" model for an electronic subsystem of matter in a rarefied state, consisting of one localized electronic state in each nucleus and delocalized electronic states considered as free ones. It is shown that, despite the qualitative agreement, there is a significant quantitative difference from the results of applying the Saha formula to the degree of ionization. This is caused by the fact that the Saha formula corresponds to the "chemical" model of matter.Comment: 9 pages, 2 figure

    PYRUS ZANGEZURA (ROSACEAE) AT SAINT PETERSBURG

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    Pyrus zangezura Maleev (Rosaceae) is a rare species representing the native vegetation of Armenia (Southern Transcaucasus). It was first described in 1936. P. zangezura has been cultivated at the Peter the Great Botanical Garden of the Komarov Botanical Institute (St. Petersburg, Russia) since 1949, where it has reached the height of 8,0 m. For many years, it was in its vegetative state. The first flowering was observed in 2016 (the plant entered the reproductive state). The first progeny from seed was obtained in April 2019. Fruit size was assessed for P. zangezura plants in the dynamics of their development. The studied plants of P. zangezura in the environments of St. Petersburg have demonstrated a high fruiting potential – on average, 109 flowers per 1 m of a shoot. Observations have shown that not all ovules in the opened flowers of P. zangezura are fertilized and produce fruits and seeds. A significant part of the opened flowers, a few days after the onset of flowering, dry up and fall off. On average, 7 fruits are set on 1 m of the shoot in P. zangezura. The reasons for the low flower setting may be variable: impaired pollination processes and insufficient fertility of pollen, underdevelopment of the flower morphological structures, or lack of pollinating insects due to adverse weather conditions. An X-ray analysis of the seeds from the harvests of 2016, 2017 and 2018 showed that the number of plump and fully developed seeds (grades IV and V) in fruits has been growing year by year. As an ornamental plant, P. zangezura may adorn any botanical garden, but it is also promising for urban landscaping, for example, in St. Petersburg. Even in the vegetative state, its elongated lanceolate glossy leaves make it appreciably different from the common P. communis L., and it is especially ornamental during flowering and fruiting. It is as winter-hardy as the common pear-tree, demonstrates resistance to diseases and pests, and may be of importance for breeding programs aimed at the development of resistant cultivars for the Northwest of Russia

    Идентификация невостребованных в транспортном процессе производственных ресурсов

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    For the English full text of the article please see the attached PDF-File (English version follows Russian version).ABSTRACT The relationship between reliability of road transportation and presence of an excess amount of production resources in the transport process is indicated. In order to reduce resource intensity of the transport process and the cost of transport work, a number of methodological recommendations on identification of spare parts, fuel and tires reserves accumulated and unclaimed during road transportation have been proposed. Examples of practical implementation of the proposed recommendations are given. Particular emphasis is placed on the fact that the funds used do not require additional costs from carriers and bring obvious economic benefits. Keywords: road transportation, transport process, consumption rates, material resources, production efficiency.Полный текст на англ. языке находится в прилагаемом файле ПДФ (англ. версия следует после русской версии).Обозначена связь надёжности автомобильных перевозок с наличием в транспортном процессе избыточного количества производственных ресурсов. С целью снижения ресурсоёмкости транспортного процесса и себестоимости транспортной работы предложен ряд методических рекомендаций по идентификации накопленных и невостребованных в ходе автомобильных перевозок резервов запасных частей, топлива и автошин. Приведены примеры практической реализации предлагаемых рекомендаций. Особый упор при этом делается на том, что используемые средства не требуют от перевозчиков дополнительных затрат и приносят очевидную экономическую выгоду

    NOVOSIBIRSK REGION PROGRAM OF THE LIVER TRANSPLANTATION IN CHILDREN

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    The aim of the study was to analyze the early and late outcomes of pediatric liver transplantation (LTx) program in the Novosibirsk region. Material and Methods. The retrospective study included 24 patients aged 72 ± 74.8 months (from 4 to 212 months, median – 20 months) with a body weight of 21.7 ± 18.1 kg (from 4.5 to 55 kg, median – 12.5 kg). Two (8.3 %) cadaveric whole liver grafts, 19 (79.2 %) living donor liver grafts, and 3 (12.5 %) cadaveric liver fragments (reduced-size or split-liver) were transplanted. Results. The features of vascular and biliary reconstruction in different types of LTx are discussed. The incidence of vascular and biliary complications was 8.3 and 20.8%, respectively. The patients stayed in the intensive care unit for 9 ± 5.1 days (from 4 to 22 days, median 8 days) and total length of hospital stay was for 40 ± 25.4 days (from 19 to 136 days, median 32 days). Two (8.3 %) recipients had early graft dysfunction. Perioperative mortality (up to 90 days) was absent. The overall 5-year patient and graft survival rates were 95 and 88 %, respectively. Conclusion. The Novosibirsk region has a pediatric LTx program with outcomes comparable to the data of the leading world and Russian centers

    Способ оценки качества точечного сварного соединения

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    The method of spot weld quality assurance of assemblies of sheets of high-strength stainless steels is developed. The X-ray optical scheme of shooting of a welding point is described. The algorithm of definition of a depth of a cast core of a spot weld is offered.Разработан способ оценки качества точечного сварного соединения сборок листов высокопрочных нержавеющих сталей. Описана рентгенооптическая схема съемки сварной точки. Предложен алгоритм определения глубины залегания литого ядра сварной точки
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