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Abstract

The present study aimed to determine the role of job components and individual parameters on the raised blood pressure among male workers of textile industry who were exposed to continuous high noise level. Information of all eligible subjects including demographic and individual characteristics, medical history and job characteristics were obtained by direct interview and referring to the medical records. All blood pressure measurements were done using mercury sphygmomanometer in the morning before work. The 8-hours equivalent A-weighted sound pressure level, the level of blood cholesterol and triglyceride, and noise annoyance was determined for each worker. As the result of weighted regression in path analysis (direct effect), only the work shift did not have a significant effect on blood pressure among the studied variables. It can be seen that variables including the level of triglyceride, cholesterol, and noise exposure have the most direct effects on blood pressure. The results of total effects showed that variables, including using the hearing protection device, age, work experience and visibility of sound source, did not have a significant effect on blood pressure. The results of this study indicate that occupational noise exposure alone and combined with other job components and individual parameters is associated with raised blood pressure. However, noise exposure was probably a stronger stressor for increased blood pressure.
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Abstract

In the paper, a general topology of continuous-time Active-RC filter is presented. The model includes all possible Active-RC filter structures as particular cases and allows us to analyze them using a unified algebraic formalism. This makes it suitable for use in computeraided analysis and design of Active-RC filters. By its construction, the model takes into account the finite DC gain and the finite bandwidth as well as non-zero output resistance of operational amplifiers. Filters with ideal OPAMPs can be treated as particular cases. Sensitivity and noise analysis of Active-RC filters is also performed in the proposed general setting. The correctness of the model is verified by comparison with SPICE simulation.
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Abstract

The area of environmental protection concern minimises the impact that technical objects have on the environment. Usually the most effective way of protecting the environment is to influence the source of the problem. For this reason studies are conducted to modify the construction of machines, power machines in particular, so as to minimise their impact on the environment. In the case of environmental protection from noise it is most convenient to carry out measurements in an anechoic chamber. Unfortunately, this is possible only in very limited circumstances. In all other cases measurements are performed using an engineering method or the survey method, both of which are described in the standards and by taking into account the so-called environmental corrections. The obtained results are burdened with greater error than those of measurements in an anechoic chamber. Therefore, it would seem advantageous to develop a method of obtaining similar and reliable results as those in an anechoic chamber, but in a reverberant field. The authors decided to use numerical modelling for this purpose. The main objective of this work is a comprehensive analysis of the numerical model of a laboratory designed for acoustic tests of selected power machines. The geometry of a room comprising an area of analysis is easy to design. The main difficulty in modelling the phenomena occurring in the analysed area can be the lack of knowing the boundary conditions. Therefore, the authors made an attempt to analyse the sensitivity of various acoustic parameters in a room in order to change these boundary conditions depending on the sound absorption coefficient
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