Full dynamic reactions in the main links of big band saw machines

In this study, the full dynamic reactions in the bearing supports of the leading wheel of big band saw machines are determined. These reactions are caused by both the external loads and the kinematic and mass characteristics of the rotating disk. Expressions for calculating the dynamic reactions caused by external forces and moments that occur in the operating mode are obtained. The influence of the kinematic and mass characteristics of the rotating disk is studied and expressions for calculating the dynamic reactions caused by these characteristics are obtained. Expressions for calculating the full dynamic reactions that load the bearing supports of the leading wheel are obtained. With the help of these expressions, the parameters of the band saw machine can be selected in such a way as to ensure a minimum load on the shaft and bearings.

Coupled flow and heat transfer of power-law Nanofluids on a non-isothermal rough rotary disk subject to magnetic field

In this paper, we study coupled flow and heat transfer of power-law nanofluids on a non-isothermal rough rotating disk subject to a magnetic field. The problem is formulated in terms of specified curvilinear orthogonal coordinate system. An improved BVP4C algorithm is proposed and numerical solutions are obtained. The influence of volume fraction, types and shapes of nanoparticles, magnetic field and power-law index on the flow and heat transfer behavior are discussed.<br/>Results show that the power-law exponents (PLE), nanoparticle volume fraction (NVF) and magnetic field inclination angle (MFIA) are almost no effects on velocities in wave surface direction, but have small or significant effects on azimuth direction. NVF have remarkable influence on local Nusselt number (LNN) and friction coefficients (FC) in radial and azimuth directions (AD). LNN increases with NVF while FC in AD decrease. The types of nanoparticles, magnetic field strength and inclination have small effects on LNN, but they have remarkable effects on the friction coefficients with positively correlated while the inclination is negatively correlated with heat transfer rate. The size of the nanoparticle shape factor is positively correlated with LNN.

Hall effect on the entropy optimization of radiative magnetized Jeffrey nanofluid flow with homogeneous and heterogeneous reaction by rotating stretching disk

Purpose: The goal of this study is to investigate the entropy optimization of Jeffrey nanofluid flow with the homogeneous and heterogeneous reaction by stretching the rotating disk. The impact of Hall current is also being considered. The process of heat transmission is carried out. For heat transfer coefficient, temperature, concentration, velocity, Bejan number, and entropy generation rate and relevant equations are computed. The implications of various characteristics are investigated. The effect of emerging parameters of nanofluid flow is discussed and represented by a graph. To reduce partial differential equations into ordinary differential equations by using effective similarity transformation. The achieved non-linear system is resolved by the Homotopy analysis technique (HAM) to found the convergent solution of the designated flow problem. The impact of various pertinent parameters, i.e thermal radiations parameter, Brinkman number, Reynolds number, magnetic parameter, Hall Effects parameter, Jeffrey nanofluid parameters are discussed and presented by the graph. Engineering quantities such as Nusselt number and skin friction are also taken into account.

Spray-Pyrolytic Tunable Structures of Mn Oxides-Based Composites for Electrocatalytic Activity Improvement in Oxygen Reduction

Hybrid nanomaterials based on manganese, cobalt, and lanthanum oxides of different morphology and phase compositions were prepared using a facile single-step ultrasonic spray pyrolysis (USP) process and tested as electrocatalysts for oxygen reduction reaction (ORR). The structural and morphological characterizations were completed by XRD and SEM-EDS. Electrochemical performance was characterized by cyclic voltammetry and linear sweep voltammetry in a rotating disk electrode assembly. All synthesized materials were found electrocatalytically active for ORR in alkaline media. Two different manganese oxide states were incorporated into a Co3O4 matrix, δ-MnO2 at 500 and 600 °C and manganese (II,III) oxide-Mn3O4 at 800 °C. The difference in crystalline structure revealed flower-like nanosheets for birnessite-MnO2 and well-defined spherical nanoparticles for material based on Mn3O4. Electrochemical responses indicate that the ORR mechanism follows a preceding step of MnO2 reduction to MnOOH. The calculated number of electrons exchanged for the hybrid materials demonstrate a four-electron oxygen reduction pathway and high electrocatalytic activity towards ORR. The comparison of molar catalytic activities points out the importance of the composition and that the synergy of Co and Mn is superior to Co3O4/La2O3 and pristine Mn oxide. The results reveal that synthesized hybrid materials are promising electrocatalysts for ORR.

Investigation of wear conditions of a composite material based on an anti-friction alloy AO20-1 reinforced with Ti particles

Сomposite material samples were obtained by the method of reaction casting by mixing titanium particles to obtain intermetallic phases Al3Ti. Dry sliding wear tests were carried out using a fixed sleeve (steel 45) against a rotating disk (sample) at sliding speeds from 0.25 to 0.75 m/s and loads from 0.5 to 3.5 MPa.There were constructed maps of wear rate, which determine the friction modes during testing. There were shown boundaries and conditions of changing wear modes.