Revista de Ciência e Engenharia Têxtil

A modified circuit for improving linearization of power amplifier based on the model of the Feed Forward circuit amplifier is proposed. With the help of mathematical model for the single power amplifier, the circuit is simulated and a demonstrator is fabricated and measured complex Taylor series are used for modeling the power amplifier by the approximation of the amplitude transfer function and the level-dependence of the transmission-phase of the power amplifier. This can be understood as a simplified form of volterra series. In our proof of concept experiment, we verified the concept but also found that the adjustment of the circuit is critically dependent on the drive conditions and linearization is achieved only for a narrow range of drive power. The proposed circuit in compared with the conventional Feed Forward amplifier in addition a significant increase in efficiency, to minimize the power of the distortion signal 3IMD-products at high drive levels.

It is known that to increase the cotton yield, getting the qualified fibre and other products depends on the preparation of cotton seed. After accepting the cotton harvest at the plant, it is initially dried up, cleaned from small and large demons and after it goes through a machine for separating cotton from its seeds. During the process of separating from its fibre seeds lose their natural quality. Prepared for planting cotton seeds under the main governmental standard UzDST663-2006/1/ and their growth depends on the degree of contamination and mechanical damage. In general, by separating the seeds with different mixes, not fully ginned and do not meet the standard of filament it is possible to prepare quality seeds.

This paper presents method of determination in the regularity change in the branches of a belt drive with an eccentric tensioning roller. On the basis of analysis in the research results identified the recommended belt transmission parameters.

Effective machining of modern day demands the new approach to designing of technology of machining which, allows considering all technological parameters of machining, as reduction of speed and reduction of giving depending on a material of an operating mode, features of the car, tools and material volume. Management of physical quantities of operations allows us to reach faster processes of machining when in comparison with old technologies of machining the current technology differs with high speed and also increases productivity. In manuscript showed energy effective method modeling and manufacturing of a new profile of a tooth of a saw.

The purpose of this research was to assess the effectiveness of two methods of reinforcing glass yarns, stitching and laminating methods, in a woven (1/1) polyethylene (PE) geotextile fabric used for fabric formwork. Both reinforcement methods improved the tensile properties when the holding load is within the combined breaking load of reinforced glass yarns. However, reinforcing by stitching method provided better tensile properties than the laminating method in respect to creep. The stitched specimens (S-1000 N) and (S-500 N) generated 7.04 mm and 0.53 mm creep respectively compared to the laminated specimens that has produced 7.56 mm (L-1000 N) and 3.11 mm (L- 500 N). A Hirsch’s model (combined effect of parallel model and series model) was used to predict the modulus of PE + glass yarn composite fabric for stitching method based on the 500 N holding load data. This modulus can be used to calculate the number of glass yarns that should be used in composite for a specific dimension of fabric formwork