INVESTIGATION OF VIBRATIONS OF A LIGHTWEIGHT GRATE ON ELASTIC SUPPORTS OF A COARSE LITTER CLEANER WITH RANDOM DISTURBANCE FROM RAW COTTON

The article discusses the results of theoretical studies of vibrations of a plastic grate on elastic supports of a coarse litter cleaner under accidental exposure to raw cotton. Graphical dependences of changes in displacements and vibration rate of the grate on changes in the coefficients of stiffness, dissipation and on the disturbing load from raw cotton at various values of the grate mass are constructed. Based on the analysis of the obtained graphical dependencies, the values of the system parameters are recommended. KEYWORDS: plastic grates, elastic supports, raw cotton, plastic pipes, mass, polyethylene, stiffness coefficient.

Coupling Properties of Chain Drive System under Various and Eccentric Loads

The chain drive system is a core subsystem of heavy scraper conveyors. During operation, violent oscillations of fluctuating loads on the chain and uneven loads at the two chain sides are observed, thus intensifying chain wear and even causing chain breakage. The dynamic properties of a chain drive system under various load and eccentric load were discussed thoroughly by combining dynamic and discrete element coupling analyses to improve the reliability of the scraper conveyor. Based on the discrete element method and multibody dynamic theory, a coupling analysis model of a scraper conveyor was constructed, and a simulation analysis on coal conveying process under various load and eccentric load was carried out. Simulation results demonstrate that the transverse vibration of the chain is positively related to coal conveying quantity, whereas longitudinal vibration is negatively correlated to coal conveying quantity. The transverse vibration rate under full loads is 513.62 % higher than that under idle condition, while the longitudinal vibration rate is 53.44 % lower. The effects of coals on transverse vibration and longitudinal vibration of a chain ring are opposite.

Inelastic rate coefficients based on an improved potential energy surface for N2 + N2 collisions in a wide temperature range

Vibration-to-translation and vibration-to-vibration rate coefficients for N2–N2 inelastic scattering are calculated on an improved potential including high temperature regimes.

Analysis Technique for the Spectral Characteristic of Acoustic Emission Signals

AE method of nondestructive check is based on exertion waves radiation and their registration during fast local material structure reorganization. It is used as a means of analysis of materials, constructions, productions control and diagnosis during operating time. When registering signal amplitude it is required to consider its frequency distribution connecting each amplitude rate with the corresponding vibration rate. With the purpose to reduce the measurement error it is required to perform receiving piezoelectric converters calibration right on the tested unit and in the process of test analysis consider “unit-converter” transfer characteristic.

Hemodynamic and ventilatory effects of manual respiratory physiotherapy techniques of chest clapping, vibration, and shaking in an animal model

Chest clapping, vibration, and shaking were studied in 10 physiotherapists who applied these techniques on an anesthetized animal model. Hemodynamic variables (such as heart rate, blood pressure, pulmonary artery pressure, and right atrial pressure) were measured during the application of these techniques to verify claims of adverse events. In addition, expired tidal volume and peak expiratory flow rate were measured to ascertain effects of these techniques. Physiotherapists in this study applied chest clapping at a rate of 6.2 ± 0.9 Hz, vibration at 10.5 ± 2.3 Hz, and shaking at 6.2 ± 2.3 Hz. With the use of these rates, esophageal pressure swings of 8.8 ± 5.0, 0.7 ± 0.3, and 1.4 ± 0.7 mmHg resulted from clapping, vibration, and shaking respectively. Variability in rates and “forces” generated by these techniques was <20% in average coefficients of variation. In addition, clinical experience accounted for 76% of the variance in vibration rate ( P = 0.001). Cardiopulmonary physiotherapy experience and layers of towel used explained ∼79% of the variance in clapping force ( P = 0.004), whereas age and clinical experience explained >80% of variance in shaking force ( P = 0.003). Application of these techniques by physiotherapists was found to have no significant effects on hemodynamic and most ventilatory variables in this study. From this study, we conclude that chest clapping, vibration, and shaking 1) can be consistently performed by physiotherapists; 2) are significantly related to physiotherapists' characteristics, particularly clinical experience; and 3) caused no significant hemodynamic effects.

Gas holdup in a reciprocating plate bioreactor: Non-Newtonian - liquid phase

The gas holdup was studied in non-newtonian liquids in a gas-liquid and gas-liquid-solid reciprocating plate bioreactor. Aqueous solutions of carboxy methyl cellulose (CMC; Lucel, Lucane, Yugoslavia) of different degrees of polymerization (PP 200 and PP 1000) and concentration (0,5 and 1%), polypropylene spheres (diameter 8.3 mm; fraction of spheres: 3.8 and 6.6% by volume) and air were used as the liquid, solid and gas phase. The gas holdup was found to be dependent on the vibration rate, the superficial gas velocity, volume fraction of solid particles and Theological properties of the liquid ohase. Both in the gas-liquid and gas-liquid-solid systems studied, the gas holdup increased with increasing vibration rate and gas flow rate. The gas holdup was higher in three-phase systems than in two-phase ones under otter operating conditions being the same. Generally the gas holdup increased with increasing the volume fraction of solid particles, due to the dispersion action of the solid particles, and decreased with increasing non-Newtonian behaviour (decreasing flow index) i.e. with increasing degree of polymerization and solution concentration of CMC applied, as a result of gas bubble coalescence.