Experimental Studies of Moisture Transport in Grain Material and Individual Grain

The issue of moisture transfer in the total mass of the material and in a single grain is discussed taking into account the biological characteristics of the endosperm cells of the grain. Experimental studies of this process have been performed. The results of the oscillating mode with laying have been analyzed. It was found that during the time of laying, the moisture content of the grain shell increases significantly and the moisture content of the core decreases slightly, and during the implementation of the laying after the heating period, a larger amount of moisture moves from the core into the shell than after the cooling period.

Research of Self-Oscillating Processes in the Zone of Interaction of an Elastic Tire with a Solid Support Base

When two bodies interact in contact, self-oscillations or relaxation vibrations can occur, which are vibrations of parts of bodies relative to each other. The study of the processes occurring in the zone of an elastic tire interaction with a solid support base is of particular interest, since they directly affect the safety of movement of wheeled vehicles. The aim of the work is to study the conditions for the occurrence of self-oscillating processes in the zone of interaction of an elastic tire with a solid support base in three rolling modes: traction, driven, and braking. It has been established that the appearance of a self-oscillating mode in the zone of interaction of an elastic tire with a solid support base is a useful diagnostic feature providing recognition of the development of the process of losing adhesion of a wheel with a support base when the rear axle skids at early stages.

Design and Characterization of a Planar Motor Drive Platform Based on Piezoelectric Hemispherical Shell Resonators

In this study, a planar ultrasonic motor platform is presented that uses three half-side excited piezoelectric hemispherical shell resonators. To understand the working principle and the harmonic vibration behavior of the piezoelectric resonator, the trajectory of the friction contact was measured in free-oscillating mode at varying excitation frequencies and voltages. The driving performance of the platform was characterized with transport loads up to 5 kg that also serve as an influencing downforce for the friction motor. The working range for various transport loads and electrical voltages up to 30 V is presented. Undesirable noise and parasitic oscillations occur above the detected excitation voltage ranges, depending on the downforce. Therefore, minimum and maximum values of the excitation voltage are reported, in which the propulsion force and the speed of the planar motor can be adjusted, and noiseless motion applies. The multidimensional driving capacity of the platform is demonstrated in two orthogonal axes and one rotary axis in open-loop driving mode, by measuring forces and velocities to confirm its suitability as a planar motor concept. The maximum measured propulsion force of the motor was 7 N with a transport load of 5 kg, and its maximum measured velocity was 77 mm/s with a transport load of 3 kg.

Effect of K-wire Reuse and Drill Mode on Heat Generation in Bone

Background We examined the effect of Kirschner wire (K-wire) reuse and use of oscillating mode on heat generation within cortical bone. Methods Two trocar-tipped K-wires were drilled through the diaphysis of each of 30 human metacarpals and phalanges: one K-wire was inserted in rotary mode and another in oscillating mode. Each wire was reused once. Thermocouples placed within the dorsal and volar bone adjacent to the K-wire drill path measured temperatures throughout each test. Results Peak cortex temperatures were 25°C to 164°C. Rotary drilling achieves peak temperatures quicker (31 ± 78 seconds vs 44 ± 78 seconds, P = .19) than oscillating drilling, but insertion time is also less, resulting in lower overall heat exposure. This effect is also seen when the K-wire is reused (34 ± 70 seconds vs 41 ± 85 seconds, P = .4). The length of time that cortical bone was exposed to critical temperatures (47°C or more) was significantly higher when a wire was reused (36 ± 72 seconds vs 43 ± 82 seconds, P = .008). Peak temperatures greater than 70°C (a temperature associated with instantaneous cell death) were observed on many occasions. Conclusions Overall heat exposure may be higher if a K-wire is reused or inserted in oscillating mode. In the absence of external cooling, K-wire insertion into cortical bone can easily expose bone to temperatures that exceed 70°C and may increase the risk of osteonecrosis.

Расчет динамики границы аморфная фаза-кристалл при твердофазной взрывной кристаллизации

The nonlinear differential equation described a dynamics of solid-phase explosive crystallization front in a much larger parameters domain in comparison with the theoretical results available in literature was obtained. The features of the self-oscillating mode transition of the front motion to the mode of its self-propagation with a constant velocity was numerically studied in detail.

EVALUATION OF THE INFLUENCE OF VELOCITY ROTOR REGIMES ON ELECTRICITY CONSUMPTION DRIVED BY A VIBRATION DISC CRUSHER

Among a number of methods for intensifying the process of grinding grain material in the technology of compound feed preparation, one of the most promising can be considered the use of a vibration field, which contributes to the formation of optimal conditions for the timely withdrawal of the finished product from the grinding zone and ensures self-cleaning of the separation surfaces from the remnants of the crushed product (especially when using non-food classes grain), thereby ensuring the maximum throughput of the machine. Given that for grinding in feed production mainly use impact machines, which are adapted to the destruction of solid and at the same time fragile objects, as well as the economic feasibility of processing substandard feed grain, which has completely opposite physical and mechanical characteristics. scheme of vibrating-rotary disk crusher. The essence of the development is to provide a combined force on the material, namely, due to the rotational and vibratory motion of the impact elements of the crusher, a combination of impact destruction and cutting material, which will process both hard and wet material without significantly reducing equipment throughput. In addition, the oscillating mode of the working chamber and, as a consequence, the separation surface will facilitate the timely removal of the finished product from the grinding zone. The next stage of creating a vibrating-rotary crusher, which precedes the design and constructive implementation is to perform theoretical calculations of its parameters, including using the methods of mathematical modeling. Thus, in order to achieve high efficiency of the process of grinding feed by the designed machine, theoretical studies of the relationship between the values of kinematic parameters of the executive bodies and electricity consumption to drive them, the main results of which are presented in the article.

An Experimental Method for Generating Shear-Free Turbulence Using Horizontal Oscillating Grids

An experimental apparatus driven by horizontal oscillating grids in a water tank is proposed for generating shear-free turbulence, which is measured using Particle Image Velocimetry (PIV). The performances of the proposed apparatus are investigated through the instantaneous and root-mean-square (RMS) velocity, Reynolds stress, length and time scale, frequency spectra and dissipation rate. Results indicate that the turbulence at the core region of the water tank, probably 8 cm in length, is identified to be shear-free. The main advantage of the turbulence driven by horizontal oscillating mode is that the ratios of the longitudinal turbulent intensities to the vertical values are between 1.5 and 2.0, consistent with those ratios in open-channel flows. Additionally, the range of the length scale can span the typical sizes of suspended particles in natural environments, and the dissipation rate also agrees with those found in natural environments. For convenience of experimental use, a formula is suggested to calculate the RMS flow velocity, which is linearly proportional to the product of oscillating stroke and frequency. The proposed experimental method in this study appears to be more appropriate than the traditional vertical oscillating mode for studying the fundamental mechanisms of vertical migratory behavior of suspended particles and contaminants in turbulent flows.

A method for determining the local mechanical properties using nanoindentation in oscillating mode

A new method of processing of data obtained using atomic force microscopy (AFM) in the oscil-lating nanoindentation mode is proposed. The model of the AFM probe on elastic beam (canti-lever) interaction with a sample is developed. In addition to the static load, applied on a base of the cantilever, a force modulation, according to a harmonic law, is set. This approach makes possible to take into account not only the force of the probe-material interaction but also the phase shift of the cantilever oscillations with respect to a given harmonic signal on the cantilever base as well as the amplitudes ratio of these oscillations. This information allows the presence of the viscosity in the material evaluating. The advantage of the oscillatory regime over quasistatic indentation was shown. It consists in the possibility to exclude the influence of irreversible pro-cesses (plastic, brittle fracture in the material) on the result of the experiment and to reveal the presence of the time dependent behavior. It is shown that the model contains a small amount of constants; methods for their determination are proposed. The calculations, performed using the developed model, made it possible to make a number of recommendations on choosing the can-tilever stiffness to obtain the most informative experimental results. This approach seems per-spective in studying materials with a high degree of stiffness inhomogeneity, including the deter-mination of the local properties of filled nanocomposites near filler particles.