РИНЦ

Рассмотрены основные материалы для нанесения покрытий. Приведены результаты исследований эксплуатационных характеристик покрытий из этих материалов.

The development enterprise show dynamic transition from traditional polarities “market” versus “state,” „private“ versus „public“ towards more complex socio-economic models, such as social enterprise. Social enterprise invokes hybridity, that emerges from the integration of traditionally separate institutional logics, ecosystems, markets, and business models. The presented research analyzes how socio-economic elements manifests at social enterprises and social enterprise ecosystem in Lithuania.

In the introduction, it is indicated the main object of the study - the weighted harmonic mean of a certain special set of numbers in the k-dimensional Euclidean space. Basic definitions and notations are given. The aim of the paper is to study the extreme properties of the harmonic mean. The idea of writing the article arose in connection with three problems presented in the book of problems of G. Polia and S. Sege “Problems and theorems in analysis”. Let a set of points be arbitrarily fixed within a circle and one variable point runs through the boundary of this circle. The Euclidean distance between a variable point and each point of a given set is determined. From these distances the geometric, arithmetic and harmonic means are formed. It is stated that the geometric mean of the distances has a minimum not greater than the radius and a maximum not less than the radius of the circle. This property of the geometric mean of distances will be called the “duality” condition. For the arithmetic mean and the harmonic mean of distances, in the case of the circle, the term “duality” is not satisfied. The above assertions are proved in the book of problems with the use of the apparatus of analytic in the disk functions. Before the main part of the work auxiliary lemmas having independent interest are given. In the main part, a weighted harmonic mean of the distances in the space with different dimensions is considered. It is proved that the maximum of the harmonic mean of distances is greater or equal to the radius and the minimum is less or equal to the radius if and only if the dimension of the space is three, i.e. the “duality” condition is satisfied. It is noted that for the arithmetic mean of distances “duality” condition is met if the dimension of the space is equal to one. The concept of a “correct set” of vectors which is used in the formulations and proofs of theorems is introduced. In the work, it is emphasized that the properties of the average distances depend on the dimension of the Euclidean space, on the number and location of points in a given space, on the radius of the sphere, and on the values of the input parameters. In the conclusion, on the basis of all the above statements, it is defined that the results obtained can have quite justified scientific interest and stimulate further work on this topic.

В данной статье приводятся результаты экспериментального исследования способа ротационно-фрикционного растачивания (РФР) отверстия детали из стали 30ХГСА. Для обработки использован ротационно-фрикционный инструмент, оснащенный чашечным резцом наплавленной материалом STOODY M7-G. Определено влияние частоты вращения шпинделя и угла установки ротационно-фрикционного инструмента на показатели качества: шероховатость и твердость обработанной поверхности. Установлено, что с увеличением частоты вращения шпинделя показатели качества поверхности улучшаются. А увеличение угла установки инструмента отрицательно влияет на показатели качества. Оптимальным углом установки инструмента установлено βу=100. При βу=100 достигнуто: шероховатость поверхности в Ra=1,25 мкм; твердость поверхности НВ 220.

Building Information Modeling (BIM) is a new possibility to create virtual model of building. The precise geometry of building comes from the data of geodetic cadastral measurements, photogrammetry (image processing), laser scanning, etc. A history of BIM, the process of cadastral measurements of buildings in the Lithuania are presented in this article. BIM is a study subject of master program “Innovation solution in Geomatics” in Department of Geodesy and Cadaster, Vilnius Gediminas Technical University. The students create virtual building models based on cadastral measurements using software ArchiCad. The experimental work - example shown in this article. Therefore, the recommendations and some remarks are written in the conclusions.

Glass Fibre Reinforced concrete (GRC) is commonly used for production of various thin- walled concrete elements due to good flexural characteristics and high ductility. For decades, typical GRC matrix consisted of fine quartz sand and ordinary Portland cement (OPC) in which short glass fibers are dispersed. Recent studies in the fields of reactive powder concrete and durability mechanisms of GRC showed that there is a big potential in improving mechanical characteristics and durability of the composite when micro or Nano fillers are used. This article investigates workability, flexural toughness and ductility of several GRC compositions with different fillers (silica sand, fine granite, fine dolomite) and micro- additives (silica powder, metakaolin and dolomite powder). Ordinary CEM I 52,5R Portland cement (OPC) is used as a binder and polycarboxylate ether-based superplasticizer (PCE) is used as water- reducing agent. 12,7mm length alkali resistant glass fibers (ARG) are dispersed for matrix reinforcement.

В работе говорится о проблемах, возникающих в строительных вузах при подготовке специалистов по дистанционной модели обучения. Для повышения качества знаний у студентов предлагается более широкое использование электронных учебников, дающих возможность: любому студенту к самообучению и самоконтролю независимо от его начальной подготовки; внедрять прогрессивные методы передачи информации; учитывать неоднородность студенческой среды; определяться с требованиями по передаче учебной информации для различных дисциплин.