Dynamic aspects of design and maintenance of the rotating machinery applied in the mining industry

In the paper a dynamic behaviour of the selected typical group of rotating machines applied in the mining industry is investigated. These are the beater mills and crushers as well as blowers and compressors, all driven by the asynchronous motors. In particular, there is considered an influence of various types of machine working tool loadings on the system lateral steady-state dynamic responses as well as a mutual torsional electromechanical interaction between the driving motor and the driven machine in transient operational conditions. The theoretical calculations have been performed by means of the advanced structural mechanical models. The conclusions drawn from computational results can be very useful during design phase of these devices as well as helpful for their users during regular maintenance.

Left ventricle: cardiac mechanics and left ventricular performance

The complexity of left ventricular (LV) function(s) assessment in heart failure patients is related to the complexity of heart anatomy, but also to the complexity of electromechanical interaction, and to the load dependency of all the parameters that could be applied in clinical practice. Three perpendicular axes orienting the global geometry of the LV define the local cardiac coordinate system: radial, circumferential, and longitudinal. Speckle tracking is the technique of choice for quantifying myocardial deformation (regional and global). Longitudinal LV deformation, which is predominantly governed by the subendocardial region, is the most vulnerable component of LV mechanics and therefore most sensitive to the presence of myocardial disease.

Heart failure: left ventricular systolic dysfunction

Heart failure (HF) is a growing problem worldwide and poses an especially large public health burden. It represents a new epidemic of cardiovascular disease, affecting nearly 5.8 million people in the United States, and over 23 million worldwide. Nevertheless, in Europe, fears of an impending HF ‘epidemic’ could not be confirmed in this analysis of trends in prevalence for the period 1990-2007 in patients hospitalized with HF in Sweden. An overall slight decrease in age-adjusted prevalence was observed from 2002. The prevalence in patients under 65 years increased markedly. In absolute numbers, there was a substantial increase among the very old, consistent with demographic changes. The complexity of left ventricular function(s) assessment in HF patients is related to the complexity of heart anatomy, but also to the complexity of electromechanical interaction, and to the load dependency of all the parameters that could be applied in clinical practice.

Fractional Order Model of Broadband Piezoelectric Energy Harvesters

This paper presents a factional model for broadband piezoelectric energy harvesting systems. Piezoelectric materials pay a significant role in harvesting ambient vibration energy. Due to their inherent characteristics and electromechanical interaction effect, piezoelectric energy harvesting exhibits the hysteresis characteristic under sweeping environmental vibration. Fractional order model of piezoelectric energy harvesting could capture the hysteresis characteristics. Simulation and experimental results show that fractional model of piezoelectric energy harvesting is more effective in describing the system dynamic.