Process fluid as a technological system element of vibro-impact parts processing

Vibro-impact processing refers to finishing processing methods, which largely determine the operational part properties. It is shown that the parameter optimization of the vibro-impact processing is a very promising area of improving the part quality and reducing their manufacturing cost.One of the most important technological system elements is the process fluid. As a result of the priory information analysis, factors that determine the parameters of the vibro-impact processing were identified.Because of theoretical studies, the process fluid parameters and flushing mode influence degree on the process parameters and treated part quality indicators was determined. The process fluid is presented as a set of unit volumes that form an elastically deformable matrix. The necessary list of initial data for determining the maximum allowable process fluid amount in the mass load volume has been identified.The dependence for determining the minimum required process fluid volume is presented. A complex parameter that characterizes the change in the load mass volume in one oscillations cycle, together with the working chamber oscillation frequency and the process fluid fluidity, which determine both the fluid flow process nature (turbulent) and the flow rate inside the load mass is proposed. Based on the complex parameter, the load mass flushing speed is determined. It is shown that at this stage, the numerical value of the parameter can only be determined experimentally. Its theoretical definition is a promising area of further research.

Spectra, eigenstates and transport properties of a $\mathcal{PT}$-symmetric ring

We study, analytically and numerically, a simple $\mathcal{PT}$-symmetric tight-binding ring with an onsite energy $a$ at the gain and loss sites. We show that if $a\neq 0$, the system generically exhibits an unbroken PT -symmetric phase. We study the nature of the spectrum in terms of the singularities in the complex parameter space as well as the behavior of the eigenstates at large values of the gain and loss strength. We find that in addition to the usual exceptional points, there are “diabolical points”, and inverse exceptional points at which complex eigenvalues reconvert into real eigenvalues. We also study the transport through the system. We calculate the total flux from the source to the drain, and how it splits along the branches of the ring. We find that while usually the density flows from the source to the drain, for certain eigenstates a stationary “backflow” of density from the drain to the source along one of the branches can occur. We also identify two types of singular eigenstates, i.e. states that do not depend on the strength of the gain and loss, and classify them in terms of their transport properties.

Experimental tests of industrial-scale ripping of soil

Ripper attachments should ensure destruction of firm, frozen or rocky soil. Industrial rippers have the ability to forcibly penetrate the working body into soil in contrast to agricultural tillage machines. The ripper attachments have two-sided force closure. The resultant forces acting on the working tool from the side of soil depend on such ripping parameters as ripping depth and angle. Currently, these dependences are mainly studied experimentally. The article presents the experimental results on the ripping resistance force as a case-study of a tractor-mounted dozer–ripper manufactured at the Chelyabinsk Tractor Plant. The scope of the experiment covers three ripping depths and eight angles. It has been experimentally found that the dependence of the ripping resistance force on each of these parameters is quadratic. The authors propose to study the ripping process using a complex parameter which is a product of the ripping depth and the ripping angle. The use of the complex parameter in the two-factor analysis allowed reducing the degree of the studied dependence while preserving the required accuracy. The complex parameter reflects the relationship between the design parameters of the ripper tooth, ripping depth and angle. The article shows that the vertical penetration resistance linearly depends on the horizontal traction resistance. The authors obtained this dependence for loam of medium density. The authors’ approach makes it possible undertake optimization of ripping process subject to soil type.

ON WEIGHTED SOLUTIONS OF $\overline{\partial}$-EQUATION IN THE UNIT DISC

In the paper an equation $\partial g(z)/\partial \overline{z} = v(z)$ is considered in the unit disc $\mathbb{D}$. For $C^k$-functions $v$ $(k = 1,2,3,\dots, \infty)$ from weighted $L^p$-classes $(1 \leq p < \infty)$ with weight functions of the type $|z|^{2\gamma} (1-|z|^{2\rho})^{\alpha}$, $z \in \mathbb{D}$, a family $g_{\beta}$ of solutions is constructed ($\beta$ is a complex parameter).

Parameters affecting the mechanical refining process of plant raw materials using a jet-impingement method

Different types of rotor-stator and jet-impingement refining equipment are used depending on the methods of production of fibre semi-finished products and on the initial state of raw materials. This article examines various refining modes for jet-impingement devices and their influence on the physical and mechanical properties of the processed material. Main design parameters that affect the refining process in this type of plant were determined. It was shown that the time required to refine a fibre mass using this plant depends on the jet flow rate (from the nozzle to the barrier), i.e. as the jet flow rate increases, the time required to refine the fibre mass decreases. A dimensionless machine parameter was obtained that characterises the effectiveness of the refining process and the design of jet-impingement refining plants. Using the dimensional method, a functional dependence was observed of breaking length, bursting strength, folding strength, and tearing strength on the machine complex parameter. The numerical value of the machine complex parameter was determined, depending on refining duration.