Volume 4, Year 2013, Issue 3, July-September
Abstract: The interaction of internal and surface waves in a two-layer fluid with free surface has been considered. The stability of wave packets propagation on the contact surface and free surface of hydrodynamic system „layer with rigid bottom - layer with free surface” was investigated. The amplitudes of the second harmonics of the elevations of the contact surface and the free surface are investigated.
Keywords: internal waves, surface waves, fluid layer, multiple scales, stability
Area: Applied Mathematics
Abstract: Microfluidic systems are used in a wide range of applications, including medical diagnostics, cell engineering and bioanalytics. In this work we focused on “Lab-on-a-chip” microsystems for cell cultivation. A troublesome problem of gas bubbles entering microdevices causing signal interferences and cells damage was emphasized. A novel, integrated debubbler in the form of cylindrical traps covered with thin PDMS membrane was designed and manufactured. Demonstrated debubbler was successfully applied in a long-lasting culture of HT-29 cell aggregates.
Keywords: gas removing system, debubbler, debubbling system, lab-on-a-chip, microfluidics, long-term cell culture, cell spheroids, HT-29 cells
Area: Biomedical Engineering
Abstract: The paper is focused on nonmonotonicity in trust management models which provide access control mechanisms for distributed systems. The work explains what decentralised systems are, defines a notion of security model nonmonotonicity, presents its types and points out factors that causes trust management model to become nonmonotonic. A result of this analysis is a model for credential revocation in the RT Framework trust management model. When security model allows for credential revocation, it becomes nonmonotonic. Presented model allows to turn it to be temporally monotonic. It allows policy authors to define constraints for roles, and applies those values to credentials. When credential does not comply to defined requirements, it is disregarded. A model is evaluated against sample scenario, which demonstrates how it can be applied to real-life use cases.
Keywords: Software security, trust management, credential revocation, RT Framework, nonmonotonicity, credential chain, credential graph, freshness constraints, freshness graph
Area: Electronics and Information Technologies
Abstract: The questions of using materials for friction units, first of all, the antifriction materials in particular on the aluminium alloy-based metal matrix take a central place in general problem of increasing the polygraph knife-machines quality. Endurance of such equipment determines a level of printing output quality. This paper summarizes the recent developments of aluminium alloy AK12MMgN industrial grinding wastes-based usage for new antifriction materials and knowledge about their manufacturing technology; specific examples will be given. Research results of new composite material physical, mechanical and tribological properties in comparison with cast alloy have been presented. The principle possibility to use the valuable industrial grinding wastes of ferrous and color metals for manufacturing of an effective parts of polygraph machines was shown.
Keywords: powder metal grinding wastes, aluminium alloy AK12MMgN, making technology, microstructure, tribological characteristics, physical mechanical properties, friction parts for polygraphic knife-machines
Area: Nanotechnologies and Materials
Abstract: The aim of this study was to analyze the technological, textural, colour and sensory characteristics of model meat products produced with the addition of egg-yolk protein preparation (by-products of phospholipids extraction process at supercritical conditions). Model meat products consisted of pork class I, backfat class I and additives such a NaCl, NaNO2 and sodium isoascorbate. Functional additive (egg-yolk protein preparation) was added at different level of concentration: 0% (C), 2% (P1), 4% (P2) and 8% (P3). Experimental stuffings were heat treated in water bath and stored for 3 weeks under refrigeration. Thermal drip, yield of production process, NaCl, NaNO2 contents, texture profile analysis and physical parameters of colour (according to the CIE L*a*b* colour scale) were determined. Sensory assessment included: overall appearance, colour, odour and consistency of model meat products. It was observed that addition of egg yolk proteins to the model meat products influenced on increasing yield of the production process and on reducing mass losses caused by heat treatment. Furthermore, the addition of protein preparate resulted in increased accumulation of sodium nitrite in experimental products, what may be take into consideration in further studies on reducing the level of this substance in meat processing. The values of hardness, gumminess and chewiness of experimental samples were higher (α ≤ 0.05) than those obtained for control variant. After 3 weeks of storage model products produced with egg-yolk protein addition were characterized by lower (α ≤ 0.05) value of chewiness than control sample. Moreover, after 24 hours there were no statistical (α ≤ 0.05) differences beetwen b* (yellowness) values of P1 variant meat products and control sausages. All investigated variants after 3 weeks of storage did not differ significantly within L* (lightness) and a* (redness) values. Sensory assessment showed that P1 variant of experimental products obtained the highest scores of colour, consistency and overall appearance.
Keywords: egg-yolk protein, meat products, functional additives
Area: Natural Sciences
Abstract: The sense of security is being mentioned as one of the most essential human needs. By talking about safety, we understand a lot of factors and aspects that considered together prove its multidimensionality. E.g., you can refer safety to issues such as globalization, demographic changes or functioning of state services. These are examples of issues which, by virtue of the changing conditions of people’s living in contemporary world, never lose their topicality. One from crucial „dimensions” of safety aspect is the spatial information, which is functioning in the world of ICT and modern technologiesÂ and is often called geoinformation. Almost all aspects of life of the contemporary man depend on it. This is because almost every object or phenomenon has its location in space and time. Without adequate spatial information it is difficult to imagine a state security, industry or citizens. For example, appropriately presented road networks, power transmission lines, or actually conducted analyses of the transport efficiency or range of phenomena, have a substantial impact on the effectiveness of the public services and the economy. They constitute also a main component of strategic and crisis management. Very important is e.g. a proper coordination of services ensuring public and property safety, in emergency situations of natural phenomena danger (such as floods, landslides) or coordination of the units responsible for country’s infrastructure.
Keywords: integrated geodetic monitoring system, landslides, geomatic, SOPO
Area: Town and Urban Planning, Architecture and Building Engineering
Abstract: Problem of upgrading the power quality for household consumers electricity has been considered. It was recommended to use the noncontact thyristor controlled transformer with unidirectional current switches. We conducted a set of calculating the power supply system parameters. This allowed to perform of power supply system elements model tests and to create electric power distribution system simulation model in the program Matlab (Simulink). We conducted research of received model and completed the analysis of modeling results.
Keywords: power-supply system, power distribution system, TCT UCS, simulation model, voltage regulation
Area: Power Engineering