RADIOLUCENT COMPOSITES PROVIDING HIGH RESISTANCE AGAINST STERILIZATION DECOMPOSITION

We present a study of radiolucent composite materials for use in medicine, providing suitable mechanical properties and high resistance against sterilization decomposition. The composites are composed of carbon (C), aramid or glass (R-glass) fabrics embedded in polydimethylsiloxane (PDMS), polyetheretherketone (PEEK) or polyphenylene sulfide (PPS) matrix. The effect of multiple steam sterilization processes on degrading the mechanical properties, structural integrity and hydrolytic decomposition of the composites was verified. The radiolucency of the composites was also investigated. The mechanical performance of ARAMID/PDMS composite is strongly influenced by the sterilization technique that is applied. The mechanical behavior of R-glass/PDMS composite during steam sterilization is negatively influenced by its porosity. The relatively high porosity of C/PDMS composite may lead to lower ultimate bending strength values, but in general its mechanical behavior is influenced only at a low rate by steam sterilization. On the basis of our analyses, we can state that both C/PEEK and C/PPS composites are good candidates for application as radiolucent materials providing resistance against sterilization decomposition

A State of the Art on Railway Simulation Modelling Software Packages and Their Application to Designing Baggage Transfer Services

There is a new baggage transfer service suggested in Newcastle Central Station. In order to prove that this service is feasible, a simulation model can be developed to test the concept and operating pattern behind. For the purposes of this paper, we intend to organize a literature review on simulation modelling software packages employed to study service design. Specifically, this paper has compared five different simulation software packages used by the railway industry to study service-related challenges. As a result, it is suggested that SIMUL8, a macroscopic discrete event-based software package, should be used among the five compared ones because of its simplicity and the ability to give practical results for the design and performance of such a baggage transfer system

A simple method of goal-directed lossy synthesis and network optimization

A simple method for synthesis of goal – directed lossy filters is described in the present paper. This method of synthesis is based on the application of optimization procedures used in usually accessible professional software for network analysis. The presented method of network optimization enable to improve network performance without requirement of special numerical programs what brings new possibility for many designers in area of network design and optimization

Anisotropy and Inhomogeneity in Extrudates of Aluminium Alloys

Anisotropy and inhomogeneity of mechanical properties and texture of microstructure originating in hot extrusion process depend not only on the type of the alloy, state of the billet and extrusion parameters, but also on the shape and size of extrudates. Tensile properties in longitudinal and transversal directions of model extrudates having simple cross-sections have been tested on four types of aluminium alloys. Values of ultimate strength and yield stress in longitudinal direction are higher up to 100 MPa as compared to those in transversal direction, whereas differences in elongation are small. Pronounced anisotropy and inhomogeneity of mechanical properties have been detected in cross-sections of the model extrudates. Quantitative metallography was used for determination of subgrain size, specific number of intermetallic phases, volume fraction of recrystallized grains and for assessment of metallographic texture. Certain implications for the die design based on obtained results are finaly presented

Development of Low-Cost Solder Paste Hand Dispenser

Nanášení pájecí pasty pomocí šablonového tisku je v případě prototypování a kusové výroby drahé a nelze rychle reagovat na změnu designu desky. V těchto případech se proto používají manuální nebo automatické dávkovače. Tato práce se zabývá vývojem nízko-nákladového ručního dávkovače, který využívá jednoduchý pružinový systém a plastovou konstrukci, uzpůsobenou pro výrobu metodou 3D tisku. Navrhované řešení umožňuje na rozdíl od jiných dávkovacích systémů kontinuální vytlačování pasty. Jak ukázal test, depozice pájecí pasty je stejně kvalitní jako u tlakového dávkovače, přitom ale výrobní náklady nečiní více než 1 euro, což je zanedbatelná částka oproti jiným, komerčním řešením.In prototyping and piece-production, stencil printing of the solder paste is expensive, and with the use of the stencil, it is not possible to react fast on changes in the design. Therefore, automatic or manual dispensers are used. This work aimed to develop a low-cost dispensing system based on a simple principle that uses torsion springs and its plastic construction is printable by a 3D printer. Unlike other dispensing systems, the presented dispenser allows continuous deposition of the solder paste. As the performance test showed, the deposition can be as good as with a commercial dispenser. Furthermore, the cost of the dispenser does not exceed 1€. In comparison with other commercial solutions, it is a negligible amount

Long-term population dynamics of the field vole from the Czech Republic

Tkadlec, E., Bejček, V., Flousek, J., Šťastný, K., Zima, J., Sedláček, F