Properties of model rubber compounds with different vulcanization activators

Influence of various vulcanization activators on properties of unfilled elastomeric compositions based on synthetic polyisoprene and oil-extended butadiene-styrene rubbers is investigated. Plastoelastic and relaxation properties, and also scorching resistance and kinetics of curing of rubber mixes with traditional and composite vulcanization activators are defined. As the composite vulcanization activator “Vulkativ-FC” was used. Its feature is the lowered content of zinc oxide and presence in the composition saturated fatty acids. The correlation of elastic and strength properties of vulcanizates with type and containing of the applied activator is established

Influence of fractional structure of the granulated nanofibrous carbon filler on electrophysical properties of epoxy composites

The effect of fractional structure of the granulated nanofiber carbon filler on the electrical properties of epoxy resin composites has been investigated in this article. The conductivity and permittivity of composite materials has been measured in the frequency range of 100 Hz – 1 MHz. It was shown that the grain-size distribution of the applied filler effects the electrical properties of epoxy resin / carbon nanofiber composites

Coherent interactions between phonons and exciton or exciton-polariton condensates

We analyse the interaction of exciton and exciton-polariton condensates in semiconductor microcavity with a coherent acoustic wave. An analytical solution for the dispersion of excitations of coupled condensate-phonon system is found in the approximation of k-independent interactions. Accounting for k-dependence results in a stronger modification of the dispersion, and even in the appearance of the "roton instability" region

The Outer Tracker Detector of the HERA-B Experiment Part I: Detector

The HERA-B Outer Tracker is a large system of planar drift chambers with about 113000 read-out channels. Its inner part has been designed to be exposed to a particle flux of up to 2.10^5 cm^-2 s^-1, thus coping with conditions similar to those expected for future hadron collider experiments. 13 superlayers, each consisting of two individual chambers, have been assembled and installed in the experiment. The stereo layers inside each chamber are composed of honeycomb drift tube modules with 5 and 10 mm diameter cells. Chamber aging is prevented by coating the cathode foils with thin layers of copper and gold, together with a proper drift gas choice. Longitudinal wire segmentation is used to limit the occupancy in the most irradiated detector regions to about 20 %. The production of 978 modules was distributed among six different laboratories and took 15 months. For all materials in the fiducial region of the detector good compromises of stability versus thickness were found. A closed-loop gas system supplies the Ar/CF4/CO2 gas mixture to all chambers. The successful operation of the HERA-B Outer Tracker shows that a large tracker can be efficiently built and safely operated under huge radiation load at a hadron collider.Comment: 28 pages, 14 figure

Students of the Middle Urals: The Transformation from Classical to Digital Community (Research Prospects)

Students are one of the most studied communities within the sociology context and especially the youths’ sociology and the sociology of education. Today, students are viewed both as the intellectual avant-garde force, leaders of social initiatives of the Russian youths and as a specific educational community. This study is based on the traditional method of document analysis, which allows us to identify key fields of the research. The research is devoted to the problems of changing students in the information society. The authors substantiate the need and prospects for studying students as a ’digital community’. A review of the social, political, sociocultural and other aspects of comprehensive students was conducted. Keywords: Actual culture, modernization of higher education, social transformation, social resource, students, digital communit

Monitoring international migration flows in Europe. Towards a statistical data base combining data from different sources

The paper reviews techniques developed in demography, geography and statistics that are useful for bridging the gap between available data on international migration flows and the information required for policy making and research. The basic idea of the paper is as follows: to establish a coherent and consistent data base that contains sufficiently detailed, up-to-date and accurate information, data from several sources should be combined. That raises issues of definition and measurement, and of how to combine data from different origins properly. The issues may be tackled more easily if the statistics that are being compiled are viewed as different outcomes or manifestations of underlying stochastic processes governing migration. The link between the processes and their outcomes is described by models, the parameters of which must be estimated from the available data. That may be done within the context of socio-demographic accounting. The paper discusses the experience of the U.S. Bureau of the Census in combining migration data from several sources. It also summarizes the many efforts in Europe to establish a coherent and consistent data base on international migration. The paper was written at IIASA. It is part of the Migration Estimation Study, which is a collaborative IIASA-University of Groningen project, funded by the Netherlands Organization for Scientific Research (NWO). The project aims at developing techniques to obtain improved estimates of international migration flows by country of origin and country of destination