Parameters Development for Optimum Deposition Rate in Laser DMD of Stainless Steel EN X3CrNiMo13-4

Laser Direct Metal Deposition (DMD) has been developed as a manufacturing process to deposit coatings on existing materials and proves advantageous in Additive Manufacturing (AM) of complex and precise components. However, it is necessary to carefully determine the proper process parameter combinations to make this method economically viable for industries. The intent of this study is to address enhancement in productivity of laser DMD of stainless steel EN X3CrNiMo13-4. Accordingly, the effects of the main laser process parameters of laser power P, scan speed v, powder flow rate $$\dot{\mathrm{m}}$$ m ˙ , and spot diameter s on track geometries and build-up rate are discussed. The regression analysis is conducted to derive correlations between the combined set of main parameters and deposition rate. The results show a good linear regression correlation of R2 >0.9 for the geometrical characteristic of aspect ratio, dilution, and deposition rate. The constructed processing map, using linear regression equations, presents proper process parameters selection in connection with deposition rate, aspect ratio, and dilution rate.

Diffusion approximations in population genetics and the rate of Muller's ratchet

Diffusion theory is a central tool of modern population genetics, yielding simple expressions for fixation probabilities and other quantities that are not easily derived from the underlying Wright-Fisher model. Unfortunately, the textbook derivation of diffusion equations as scaling limits requires evolutionary parameters (selection coefficients, mutation rates) to scale like the inverse population size---a severe restriction that does not always reflect biological reality. Here we note that the Wright-Fisher model can be approximated by diffusion equations under more general conditions, including in regimes where selection and/or mutation are strong compared to genetic drift. As an illustration, we use a diffusion approximation of the Wright-Fisher model to improve estimates for the expected time to fixation of a strongly deleterious allele, i.e. the rate of Muller's ratchet.

ПРОЕКТУВАННЯ СТУЛКОВОГО ВІДСІКУ ХВОСТОВИХ ВАНТАЖНИХ ЛЮКІВ ЛІТАКІВ ТРАНСПОРТНОЇ КАТЕГОРІЇ

The method for determining the main parameters of the tail cargo doors of transport category aircraft is developed. There have been prepared initial data and described the methodology for finding them. An example based on an existing transport aircraft is considered. The basic nomenclature of transported cargoes of the designed aircraft, its dimensions and weight, methods of loading and mooring, additional loading equipment were taken as initial data. As well as such necessary design, operational and regulatory parameters and data as landing gear type, its “kneeling” system, rails of the upper loading equipment for loading and unloading, cargo trajectories during loading and landing, requirements of international regulatory organizations FAR, CS, AP. The principle of determining the dimensions of the cargo compartment, cargo floor and the hitting platforms in the form of ramp with pressure door, ladders is presented, based on the initial data. Taking into account the loading and unloading, landing operations described the dependence of the ramp length on the length of the cargo floor. The correct formation of these parameters is one of the most important tasks, from the solution of which directly depend the operational characteristics of the future transport aircraft. A method for designing cargo door fairings in the transport category aircraft fuselage tail part is also presented. There have been determined the main features of the fairings compartment, its main components and their varieties, depending on the scheme of the cargo door. At the stage of preliminary design, the principles for determining the main parameters of the fairings compartments based on their design purpose are outlined.Also provided information on the fairings compartment structural elements parameters selection: the axes of the fairings hinge, the selection of control cylinders and their installation, the parameters of the open and closed position locks, pressurization and sealing of the fairings compartment. Considered the design features of the fuselage tail section various theories fairings compartment - made in cross-section with one radius (in the shape of a cylinder) and given in cross-section with two radii (double-deck).

Intelligent Algorithm for Variable Scale Adaptive Feature Separation of Mechanical Composite Fault Signals

With the development of modern industry and scientific technology, production equipment plays an increasingly important role in military and industrial production, and the fault detection signal of gears and bearings state in transmission equipment becomes very important. Therefore, this paper proposes a gear-bearing composite fault signal decomposition and reconstruction method, which combines the marine predator algorithm (MPA) and variational mode decomposition (VMD) technologies. For the parameters’ selection of VMD, the optimization algorithm allows us to quickly and accurately obtain the results with the best kurtosis correlation index after signal decomposition and reconstruction. The experiments demonstrate the excellent performance of our method in the field of separation and denoising mixed gear-bearing fault signals.

An Efficient Mixed Finite Element Perfectly Matched Layer with Optimal Parameters Selection for Two-Dimensional Time Domain Soil-Structure Interaction Analysis

Perfectly matched layer (PML) is known as one of the best methods to simulate infinite domains in many fields such as soil-structure interaction (SSI). The performance of PML is significantly affected by PML parameters selection. However, the way to select PML parameters still remains unclear. This study proposes a method for PML parameters determination for elastic wave propagation in two-dimensional (2D) media. The scaling and attenuation functions are developed in order to increase the accuracy and effectiveness of the PML. The proposed scheme is applied for a mixed PML in time domain. The finite element method (FEM) formulations of the PML are presented so that it can be easily applied to the existing codes. ABAQUS, a popular FEM code, is used for numerical applications in this study. The proposed PML is imported into ABAQUS by using a user-defined element (UEL) written in Fortran language. Six numerical analyses of SSI are implemented to prove the efficiency of the proposed PML. The numerical analyses cover many realistic problems, including free field, surface structure, and embedded structure problems. The results demonstrate the efficiency of the proposed PML in terms of the accuracy and computational cost.