10 research outputs found
Investigation of the influence of high hydrostatic pressure on the abrasive wear of hard-alloy materials
No full textCratonic conditions beneath Arkhangelsk, Russia: garnet peridotites from the Grib kimberlite
No full textМотивационные аспекты изучения математики студентами «гуманитарных» специальностей
Get PDFMathematical models, which are means to reflect almost all processes and phenomena, penetrate intensively into all life spheres and play an important role in both natural science, engineering research and humanities. In this regard, new requirements are being put forward for training future specialists of various qualifications, to form professional competencies of which it’s necessary to master mathematics foundations. The article substantiates the importance to form mathematical competence of students of humanitarian specialties. Under the humanitarian specialties here, we mean specialties related to business, such as «Trade», «Management», «Marketing», «Advertising and public relations», etc. At the same time, the authors note that each specialty has a component reflecting and modeling real situations in the industry, which is quite interesting and accessible to junior students of the listed specialties and can be demonstrated even in the math basic course. The article emphasize that the topic relevance is dictated by the transition to a competency-based learning model, which, among other things, implies the development of independent learning skills among university students. The paper shows that the introduction of professional orientation in teaching mathematical disciplines is complicated by the lack of appropriate technologies and standards, as well as by a drop in the level of school mathematics training. It analyzes some aspects of this issue and emphasizes that motivational aspects should be put at the forefront while developing mathematics courses for students of humanitarian specialties of the university. The authors conclude that the competent mathematics course elaboration for students studying in the humanities will help to understand the importance of mathematical foundations for their further growth, awaken their desire to analyze, highlight the main thing, reason, see many ways to solve professional problems.Математические модели, являющиеся средством отражения практически всех процессов и явлений, сильнее проникают во все сферы жизни и играют важную роль не только в естественно-научных и инженерно-технических исследованиях, но и гуманитарных. В связи с этим выдвигают новые требования к подготовке будущих специалистов разных квалификаций, для формирования профессиональных компетенций которых освоение основ математики является необходимым. В статье обоснована важность формирования математической компетентности студентов гуманитарных специальностей. Под гуманитарными специальностями имеются в виду специальности, так или иначе связанные с бизнесом, как, например, «Торговое дело», «Менеджмент», «Маркетинг», «Реклама и связи с общественностью» и пр. При этом отмечено, что в каждой специальности существует составляющая, которая, отражая и моделируя реальные ситуации в отрасли, достаточно интересна и доступна студентам младших курсов перечисленных специальностей и может быть продемонстрирована даже в базовом курсе математики. Подчеркнуто, что актуальность этой тематики продиктована переходом к компетентностной модели обучения, которая в том числе подразумевает развитие у студентов вузов навыков самостоятельного обучения. Отмечено, что внедрение профессиональной направленности обучения математическим дисциплинам осложняется отсутствием соответствующих технологий и стандартов, а также падением уровня школьной математической подготовки. Проанализированы некоторые аспекты этой проблемы и сделан акцент на том, что при разработке курсов математики для студентов гуманитарных специальностей вуза должны быть приоритетными мотивационные аспекты. Сделан вывод о том, что релевантное построение курса математики для студентов, обучающихся на гуманитарных специальностях, поможет понять важность математических основ для их дальнейшего роста, пробудить в них желание анализировать, выделять главное, рассуждать, видеть множество путей для решения профессиональных задач
Urban growth and heat islands: A case study in micro-territories for urban sustainability
Get PDF[EN] Rapid urbanization contributes to the development of phenomena such as climate variability, especially in tropical countries, which negatively impact ecosystems and humans, factors that influence urban sustainability. Additionally, the increase of building construction prevents the flow of wind streams contributing to the retention of pollutants and hot air masses, causing events such as urban heat islands (UHI). This study aimed to analyze from the micro-territorial level, the influence of urban growth on the UHI phenomenon over the last two decades (2000¿2020) in the locality of Kennedy, in Bogotá, Colombia. For this purpose, environmental and socio-economic factors were evaluated. For the former, Landsat satellite images and spectral indices were used to evaluate the spatial¿temporal variation in the quantity and quality of vegetation, bodies of water, urbanized areas, impervious surfaces, as well as to calculate the land surface temperature and its distribution in the study area. With regard to the socio-economic factors, the variables considered for analysis were population density and energy consumption. Lastly, a principal component analysis was carried out to identify possible associations between the variables and to identify the contribution of each micro-territory to the UHI phenomenon in the study area. 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Observer form of the hyperbolic type generalized Lorenz system and its use for chaos synchronization
Get PDFsummary:This paper shows that a large class of chaotic systems, introduced in [S. Čelikovský and G. Chen: Hyperbolic-type generalized Lorenz system and its canonical form. In: Proc. 15th Triennial World Congress of IFAC, Barcelona 2002, CD ROM], as the hyperbolic-type generalized Lorenz system, can be systematically used to generate synchronized chaotic oscillations. While the generalized Lorenz system unifies the famous Lorenz system and Chen’s system [G. Chen and T. Ueta: Yet another chaotic attractor. Internat. J. Bifur. Chaos 9 (1999)], the hyperbolic-type generalized Lorenz system is in some way complementary to it. Synchronization of two such systems is made through a scalar coupling signal based on nonlinear observer design using special change of coordinates to the so-called observer canonical form of the hyperbolic-type generalized Lorenz system. The properties of the suggested synchronization that make it attractive for the the secure encrypted communication application are discussed in detail. Theoretical results are supported by the computer simulations, showing viability of the suggested approach
О ВРЕМЕНИ ФОРМИРОВАНИЯ КАНДАЛАКШСКОГО И КЕРЕЦКОГО ГРАБЕНОВ ПАЛЕОРИФТОВОЙ СИСТЕМЫ БЕЛОГО МОРЯ В СВЕТЕ НОВЫХ ДАННЫХ ИЗОТОПНОЙ ГЕОХРОНОЛОГИИ
Get PDFInitially, the age and stratigraphic position of the Tersk formation were determined with respect to the fact that this formation overlaps the Early Proterozoic granitoids. Its top was marked by the rocks penetrated by the Late Devonian alkaline intrusions, including explosion pipes.This article presents the U-Pb isotopic dating of detrital zircon grains (dZr) from sandstones of the Tersk formation. It describes the geochemical compositions of the rocks and the Sm-Nd study results. In our study, the weighted average age of four youngest dZr grains from the sandstones of the Tersk formation is 1145±20 Ma, which suggests that the rocks above the studied rock layer (see the Tersk formation cross-section) are is not older than the end of the Middle Riphean. The U-Pb isotopic ages of dZr grains (provenance signals) from the sandstones of the Tersk formation were compared to the ages of other Upper Precambrian clastic strata in the northeastern East European platform (EEP) and adjacent areas. Our comparative analysis shows that these rocks significantly differ in age. This conclusion is in good agreement with the idea that at the end of the Middle and during the Late Riphean, several small (mainly closed) basins separated by uplifts dominated in the paleogeographic setting of the area wherein the White Sea rift system (WSRS) formed and developed. Temporal connections of these basins with the ocean were possible. Such paleogeographic setting does not favour the development of large rivers; this is why the grabens are mainly filled with local rock materials. The Keretsk and Kandalaksha grabens (WSRS) are filled with marine sediments eroded from the grabens walls. The local sediment sources include eclogite complexes (~1.9 Ga), which basic magmatism is dated at ~2.4–2.5 and ~2.7–2.9 Ga. Any potential primary sources for dZr grains are lacking in the area near the Keretsk graben. We suggest that such grains occurred due to recycling of the secondary sources of zircon, i.e. originated from ancient local sedimentary formations.На начальном этапе исследований возраст и стратиграфическое положение терской свиты ограничивались снизу ее налеганием на раннепротерозойские гранитоиды, а сверху – тем, что породы терской свиты вмещают позднедевонские щелочные интрузии (в том числе и трубки взрыва).В статье представлены результаты U-Pb изотопного датирования зерен детритового циркона (dZr) из песчаников терской свиты, дополненные определениями химического состава пород и результатами их изотопного Sm-Nd изучения. Полученный средневзвешенный возраст четырех наиболее молодых зерен dZr из песчаников терской свиты составил 1145±20 млн лет, что означает, что часть разреза терской свиты, залегающая выше изученного уровня, не может быть древнее конца среднего рифея. Сравнительный анализ полученного набора U-Pb изотопных датировок зерен dZr (провенанс-сигнала) из песчаников терской свиты и аналогичных данных по другим верхнедокембрийским обломочным толщам, распространенным на северо-востоке Восточно-Европейской платформы и в сопредельных регионах, выявил существенные различия. Это находится в хорошем соответствии с представлениями о том, что палеогеографическую обстановку, господствовавшую в конце среднего и в позднем рифее в области заложения и развития рифтовой системы Белого моря (РСБМ), можно рассматривать как совокупность небольших (часто бессточных) бассейнов, разделенных поднятиями. Эти бассейны могли время от времени иметь связь с Мировым океаном. Такая палеогеографическая ситуация не благоприятствовала развитию крупных рек, поэтому грабены заполнялись преимущественно материалом местного происхождения. Кандалакшский и Керецкий грабены РСБМ заполнены осадками морского генезиса, представляющими собой преимущественно продукты размыва вещественных комплексов, участвующих в строении бортов этих грабенов. Среди местных локальных источников идентифицированы эклогитовые комплексы с возрастом метаморфизма ~1.9 млрд лет и базитовового магматизма с возрастом ~2.4–2.5 и ~2.7–2.9 млрд лет. Попадание зерен dZr, для которых нет потенциальных близких первичных источников, расположенных около Керецкого грабена, произошло за счет рециклинга из вторичных источников циркона – местных древних осадочных образований
Generalized synchronization in the networks with directed acyclic structure
Get PDFsummary:Generalized synchronization in the direct acyclic networks, i.e. the networks represented by the directed tree, is presented here. Network nodes consist of copies of the so-called generalized Lorenz system with possibly different parameters yet mutually structurally equivalent. The difference in parameters actually requires the generalized synchronization rather than the identical one. As the class of generalized Lorenz systems includes the well-known particular classes such as (classical) Lorenz system, Chen system, or Lü system, all these classes can be synchronized using the presented approach as well. The main theorem is rigorously mathematically formulated and proved in detail. Extensive numerical simulations are included to illustrate and further substantiate these theoretical results. Moreover, during these numerical experiments, the so-called duplicated system approach is used to double-check the generalized synchronization
ВЗАИМОДЕЙСТВИЕ ГИБКОЙ КОЛЕСНОЙ ПАРЫ И РЕЛЬСОВ С ВОЛНООБРАЗНЫМ ИЗНОСОМ
Get PDFRailway track represents a periodic structure. In the presence of short-pitch rail corrugation, a wheel moving at high speed induces the vibrations whose frequency is greater than the frequency of the second symmetric flexural mode of a wheel-set. Therefore, the wheel-set cannot be regarded as a rigid body. In this study, the wheel-set is modeled by means of five lumped masses connected to a weightless flexible axle. These masses correspond to the boxes, to the wheels and to the wheel-set axle. Contact deformation due to a periodic contact force between the wheel and the rail causes an approach of the wheel centre to the rail centre-line. This approach is calculated by means of non-linear contact mechanics. The periodically varying curvature of the rail vertical profile causes periodic variation in the wheel-rail contact stiffness whose period equals the corrugation length. The above force is determined by means of Fourier series.Автор рассматривает особенности взаимодействия равномерно движущихся и равноотстоящих друг от друга колесных пар на рельсах с волнообразным износом. В качестве расчетного поля используется периодическая модель железнодорожного пути. Вычисления сделаны с помощью ряда Фурье. Исследуются качение колеса, гибкая колесная пара, различные модельные схемы. Сделанные расчеты позволяют внести существенные уточнения в теоретические положения, касающиеся высокочастотных колебаний рельсового пути.
Challenges and perspectives of the use of photovoltaic solar energy in Colombia
Get PDFThis article quantifies the development of photovoltaic solar energy in Colombia and its current development prospects. The high demand for electricity in Colombia is increasing since there is a large population, industrial, and business increase, which brings a higher energy consumption and consequently economic, social, and environmental problems. Faced with this situation, a possible solution is proposed, using solar energy, to supply the increase in demand and mitigate the problems caused by current electricity generation because Colombia has high levels of solar radiation in almost the entire territory. The objective of this research is based on the analysis of the behavior of the projects on photovoltaic solar systems presented to the mining-energy planning unit (UPME) in the last 14 years until September 30, 2020, as well such as the study of the areas with the most effective implementation of this technology and their respective radiation indices. In addition, a synthesis is made of the regulations, laws, and tax incentives that exist for the implementation of this technology and the different stages of execution of the projects approved and in performance
Estrategias sostenibles para proyectar espacios confortables mitigadores de la polución y promotores de los ODS, de acuerdo con los criterios LEED
No full textArtículo científicoEste artículo científico propone diversas pautas de diseño para crear un edificio con un entorno confortable y mimetizado con el ambiente por medio de la utilización óptima de los recursos, el aprovechamiento de espacios amplios y lugares naturales, el uso eficiente de energía y materiales, y un buen ambiente interno. Esto, basado en el sistema de calificación de liderazgo en energía y diseño ambiental (avalado internacionalmente), con el fin de contribuir al incremento de la proyección arquitectónica sustentable, de tal manera que las personas puedan habitar espacios ambientalmente responsables y mejore así tanto su calidad de vida, como la del aire, el agua y el suelo. Estas estrategias proyectuales serán evaluadas mediante el análisis de cuatro edificaciones, las cuales se ubican en Bogotá; tres de ellas son residenciales, y la cuarta es un centro de la felicidad desarrollado para una población vulnerable por lo que se busca dar resolución a varias problemáticas, entre estas: ambientales y socioeconómicas. (Tomado de la fuente).PregradoArquitectoINTRODUCCIÓN
Contaminación global
Casos por evaluar
ESTADO DEL ARTE
Planificación
Sustentabilidad
Energía neta cero
METODOLOGÍA
Bioclimática
Criterios LEED
Características de la Arquitectura Sostenible
Revitalización y desarrollo
RESULTADOS
Caso 1 Kubik Virrey
Caso 2 Hotel Grand Hyatt
Caso 3 Hotel Aloft Aeropuerto
Parque ecológico y C.E.F.E. Centro de la felicidad
DISEÑO SOSTENIBLE
Sitios sostenibles
Eficiencia de agua
Energía y atmósfera
Recursos materiales
Calidad ambiental interior
CONCLUSIONES
REFERENCIA
