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Number of results: 6
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Abstract

For the purpose of making of a solid body of an electric guitar the acoustic- and mechanical properties of walnut- (Juglans regia L.) and ash wood (Fraxinus excelsior L.) were researched. The acoustic properties were determined in a flexural vibration response of laboratory conditioned wood elements of 430 × 186 × 42.8 mm used for making of a solid body of an electric guitar. The velocity of shearand compression ultrasonic waves was additionally determined in parallel small oriented samples of 80 × 40 × 40 mm. The research confirmed better mechanical properties of ash wood, that is, the larger modulus of elasticity and shear modules in all anatomical directions and planes. The acoustic quality of ash wood was better only in the basic vibration mode. Walnut was, on the other hand, lighter and more homogenous and had lower acoustic- and mechanical anisotropy. Additionally, reduced damping of walnut at higher vibration modes is assumed to have a positive impact on the vibration response of future modelled and built solid bodies of electric guitars. When choosing walnut wood, better energy transfer is expected at a similar string playing frequency and a structure resonance of the electric guitar.
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Abstract

Effects from adsorption of organic species on the surface of nanomaterials have been investigated. Exposure to organic contaminants during material processing, handling and environmental exposure is unavoidable during the manufacturing process of nanoscale materials. In addition, at the nanoscale, surface area to volume ratios increase and surface effects will have an increasing influence on the material properties. Experimentally measured electrical properties of gold nanowires and composition will be presented. The results indicated that C, C—O—C and C=O are adsorbed at the surface of the gold nanowires. These surface contaminants are believed to cause the increase in measured resistivity. A theoretical study was performed to investigate diffusion of these contaminants into the first surface layer, which may act as scattering mechanisms for current flow.
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Abstract

Within the research, selected multilayer technological systems created as combinations of water-glass containing moulding sand with foundry tooling, were characterised on the grounds of their electrical properties. By measuring resonance frequency and quality factor of a waveguide resonance cavity, real component of permittivity εr′ and loss tangent tgδ were determined for multilayer foundry systems with various qualitative and quantitative compositions. It was demonstrated that combination of a sandmix and foundry tooling with known dielectric properties results in a system with different physico-chemical properties, whose relation to the parameters of individual components of the system is undefined at this research stage. On the grounds of measurement results, theoretical value of microwave heating power, dissipated in unit volume of the selected multilayer foundry system, was determined. Knowledge of theoretical heating power and evaluation of physical, chemical and structural changes occurring in moulding sands exposed to microwaves in such a technological system makes a ground for empirical modelling of the process of microwave heating of foundry moulds and cores.
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Abstract

In the paper presented are results of a research on influence of electrical and physico-chemical properties of materials being parts of multicomponent and multimaterial systems used in foundry practice on efficiency and effectiveness of microwave heating. Effectiveness of the process was evaluated on the grounds of analysis of interaction between selected parameters of permittivity and loss factor, as well as collective index of energy absorbed, reflected and transmitted by these materials. In the examinations used was a stand of waveguide resonance cavity for determining electrical properties and a stand of microwave slot line for determining balance of microwave power emitted into selected materials. The examinations have brought closer the possibility of forecasting the behaviour of multimaterial systems like e.g. model, moulding sand or moulding box in microwave field on the grounds of various electrical and physico-chemical properties. On the grounds of analysis of the results, possible was selecting a group of materials designed for building foundry instrumentation to be effectively used in electromagnetic field.
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Abstract

In this paper, explain the preparation of CaTiO3 ceramics synthesized by the solid-state reaction method. Calcium carbonate and titanium dioxide were high energy mixed in stoichiometric amounts, and the obtained mixture was calcined at different temperatures (800, 900, 1000 and 1300ºC) for 2 h. The obtained samples were characterized by measurement of particle size, Energy Dispersive X-Ray (EDX) Analysis; differential thermal analysis, X-ray diffraction and SEM images. XRD patterns indicated that CaTiO3 ceramics with the structure of perovskite is obtained from calcined powders at 1,300°C for 2 h. SEM images show the formation of a very fine and homogeneous morphology. The measured values of electrical resistivity were within the typical range of insulating materials and approach values corresponding to insulating ceramics.
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Abstract

This paper presents the concept and modern technological approach to the fabrication of discrete, integrated and integral micropassives. The role of these components in modern electronic circuits is discussed too. The material, technological and constructional solutions and their relation with electrical and stability properties are analyzed in details for linear and nonlinear microresistors made and characterized at the Faculty of Microsystem Technology, Wrocław University of Technology.
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