The Effect of Coatings on Cutting Force in Turning of C45 Steel

This article focuses on the development of a mathematical model of a cutting force that is applicable for coated and uncoated cutting tool inserts and aims to enable more accurate calculation of the cutting force. Two common PVD coatings, AlTiN and TiAlCrN, were used. Firstly, a mathematical model of the cutting force based on the specific cutting force and cutting area is proposed. This mathematical model considers the cutting speed and coating correction factor as well as the real cutting edge geometry, i.e., it includes both the straight and rounded parts of the cutting edge. For this proposed model, material constants for C45 steel, which was machined with uncoated inserts, were obtained. Before determining an equation for a coating correction factor and implementing it into the model, experimental cutting force data for coated and uncoated inserts were compared using a paired t-test. The result was that the difference between them was statistically significant. Their percentage difference was found to be up to 4%. The correction factor equation that was obtained and implemented into the mathematical model was applied to compare the calculated and experimental data of the coated inserts, also using a paired t-test. The result was that the difference between them was insignificant. Moreover, their percentage difference was found to be up to 0.6%.

The magnetic field dependent displacement effect and its correction in reference and relative dosimetry

Objective This study investigates the perturbation correction factors of air-filled ionization chambers regarding their depth and magnetic field dependence. Focus has been placed on the displacement or gradient correction factor Pgr. Besides, the shift of the effective point of measurement Peff that can be applied to account for the gradient effect has been compared between the cases with and without magnetic field. Approach The perturbation correction factors have been simulated by stepwise modifications of the models of three ionization chambers (Farmer 30013, Semiflex 3D 31021 and PinPoint 3D 31022, all from PTW Freiburg). A 10 cm x 10 cm 6 MV photon beam perpendicular to the chamber’s axis was used. A 1.5 T magnetic field was aligned parallel to the chamber’s axis. The correction factors were determined between 0.4 and 20 cm depth. The shift of Peff from the chamber's reference point Pref, ∆z, was determined by minimizing the variation of the ratio between dose-to-water Dw(zref+∆z) and the dose-to-air Dair(zref) along the depth. Main Results The perturbation correction factors with and without magnetic field are depth dependent in the build-up region but can be considered as constant beyond the depth of dose maximum. Additionally, the correction factors are modified by the magnetic field. Pgr at the reference depth is found to be larger in 1.5 T magnetic field than in the magnetic field free case, where an increase of up to 1% is obserbed for the largest chamber (Farmer 30013). The magnitude of ∆z for all chambers decreases by 40% in a 1.5 T magnetic field with the sign of ∆z remains negative. Significance In reference dosimetry, the change of Pgr in a magnetic field can be corrected by applying the magnetic field correction factor kB Qmsr when the chamber is positioned with its Pref at the depth of measurement. However, due to the depth dependence of the perturbation factors, it is more convenient to apply the ∆z-shift during chamber positioning in relative dosimetry.

OPTIMIZATION OF METHODS AND PARAMETERS OF PRE-START THERMAL PREPARATION OF THE ENGINE FOR STARTING DEPENDING ON THE AMBIENT TEMPERATURE

Due to the lack of a generally accepted methodology for calculating the starting processes of automotive diesel engines, today it is not possible to calculate their temperature parameters with a sufficient degree of accuracy during start-up, which determine the condition of a guaranteed start-up process. The main problem in applying theoretical calculations is that they take into account the compression ratio of the engine. But the compression ratio and the value of the actual pressure in the engine cylinders during the start-up are completely different indicators. The purpose of this work is to correct the generally accepted dependencies for determining the temperature parameters of a diesel engine by introducing a correction factor that takes into account the reduced pressure in the engine cylinders during start-up, as well as calculating the temperature parameters during start-up according to the proposed calculation method. The correction factor is determined experimentally and depends on the engine temperature. When applying the correction factor, it becomes possible to accurately calculate the temperature of the fuel-air mixture, which determines the possibility of a guaranteed start-up process and at the same time allows you to set the minimum necessary requirements for the means of thermal pre-start preparation. A group of graduate students and teachers (Izhevsk State Agricultural Academy and Kazan Agrarian University) conducted a number of practical studies on the basis of one of the leading agricultural enterprises of the Udmurt Republic JSC "Ilyich's Way". The MTZ-82 tractor was taken as the object of the study. The subject of the study was the launch of its D-243 engine at low temperatures in real operating conditions. The choice of this model of diesel engine is due to its wide application on tractors. The studies were carried out according to the approved test program, which consists in starting the D-243 engine of the MTZ-82 tractor at temperatures from - 30 ° C with an interval of 5 ° C to +5 ° C (engine temperature is equal to ambient temperature), as well as from +5 ° C to +90 ° C with an interval of 20 ° C (ambient temperature +20 ° C). Measurements were carried out to determine the amount of compression in the engine cylinders and the speed of rotation of the crankshaft at certain temperatures. The experiments were carried out using a starter charger that provides the full electric power of the diesel starter. As a result of the experimental work carried out, a change in the value of the correction coefficient from the engine temperature was established, and in accordance with the modified methodology of theoretical calculations, the values of the temperature of the fuel-air mixture at the end of the compression stroke of the diesel engine at start-up are given. It is established that the minimum required pre-start temperature of the diesel engine should be at least +5 ° C. Based on the results of the analysis of calculations, the directions of ensuring a guaranteed start of the diesel engine by simultaneously heating the coolant and engine oil are proposed. These requirements can be provided by a thermal storage system that does not require additional energy sources for its operation

Investigating The Efficiency Of The VPR And COFFE Area Models In Predicting The Layout Area Of FPGA Lookup Tables

A single tile in a mesh-based FPGA includes both the routing block and the logic block. The area estimate of a tile in an FPGA is used to determine the physical length of an FPGA’s routing segments. An estimate of the physical length of the routing segments is needed in order to accurately assess the performance of a proposed FPGA architecture. The VPR (Versatile Place and Route) and the COFFE (Circuit Optimization for FPGA Exploration) tools are widely used meshbased FPGA exploration environments. These tools map, place, and route benchmark circuits on FPGA architectures. Subsequently, based on area and delay measurements, the best architectural parameters of an FPGA are decided. The area models of the VPR and COFEE tools take only transistor size as input to estimate the area of a circuit. Realistically, the layout area of a circuit depends on both the transistor size and the number of metal layers that are available to route the circuit. This work measures the effect of the number of metal layers that are available for routing on FPGA layout area through a series of carefully laid out 4-LUTs (4-input Lookup Tables). Based on measured results, a correction factor for the COFFE area equation is determined. The correction factor is a function of both the transistor drive strength and the number of metal layers that are available for routing. Consequently, a new area estimation equation, that is based on the COFFE area model, is determined. The proposed area equation takes into consideration the effect of both the transistor drive strength and the number of metal layers that are available for routing on layout area. The area prediction error of the proposed area equation is significantly less than the area prediction errors of the VPR and COFFE area models.

Investigating The Efficiency Of The VPR And COFFE Area Models In Predicting The Layout Area Of FPGA Lookup Tables

A single tile in a mesh-based FPGA includes both the routing block and the logic block. The area estimate of a tile in an FPGA is used to determine the physical length of an FPGA’s routing segments. An estimate of the physical length of the routing segments is needed in order to accurately assess the performance of a proposed FPGA architecture. The VPR (Versatile Place and Route) and the COFFE (Circuit Optimization for FPGA Exploration) tools are widely used meshbased FPGA exploration environments. These tools map, place, and route benchmark circuits on FPGA architectures. Subsequently, based on area and delay measurements, the best architectural parameters of an FPGA are decided. The area models of the VPR and COFEE tools take only transistor size as input to estimate the area of a circuit. Realistically, the layout area of a circuit depends on both the transistor size and the number of metal layers that are available to route the circuit. This work measures the effect of the number of metal layers that are available for routing on FPGA layout area through a series of carefully laid out 4-LUTs (4-input Lookup Tables). Based on measured results, a correction factor for the COFFE area equation is determined. The correction factor is a function of both the transistor drive strength and the number of metal layers that are available for routing. Consequently, a new area estimation equation, that is based on the COFFE area model, is determined. The proposed area equation takes into consideration the effect of both the transistor drive strength and the number of metal layers that are available for routing on layout area. The area prediction error of the proposed area equation is significantly less than the area prediction errors of the VPR and COFFE area models.

Analytical solution of the problem of dynamic synthesis of a six-link straight-line converting mechanism of the sucker-rod pumping drive

The paper presents an analytical solution to the problem of optimal dynamic balancing of the six-link converting mechanism of the sucker-rod pumping unit. This problem is solved numerically using a computer model of dynamics, namely by selecting the value of the correction factor k. Here we will consider an analytical method for solving this problem, that is, we find the location of the counterweight on the third link of the six-link converting mechanism for balancing. To solve the problem, we use the principle of possible displacement and write an equation where we express the torque through the unknown parameter of the counterweight. Further, such a value of the unknown parameter is found, at which the minimum of the root-mean-square value of torque M is reached. From the condition of the minimum of the function, we obtain an equation for determining the location of the counterweight. Thus, we obtain an analytical solution to the problem of optimal dynamic balancing of the six-link converting mechanism of the sucker-rod pumping drive in various settings. According to the results, it was found that with the combined balancing method, the value of the maximum torque M and the value of the maximum power are reduced by 20 % than when the counterweight is placed on the third link of the converting mechanism, as well as when the value of the maximum torque is determined through the correction factor k. In practice, balancing is carried out empirically by comparing two peaks of torque M on the crank shaft per cycle of the mechanism movement. Solving the analytical problem, we determine the exact location of the counterweight.

The Method to Determine the Turns Ratio Correction of the Inductive Current Transformer

This paper presents the method for evaluation of the turns ratio correction of the inductive current transformer using the magnetization curves determined at the non-load state and in the load conditions. The presented method may be applied to determine even a fractional winding correction factor. The standard IEC 61869-2 provides the method to determine the turns ratio correction of the tested CT from the measured rms values of voltages on its primary and secondary winding in the non-load state. However, this approach is limited in determining the significant changes in the number of turns of the secondary winding. Moreover, the paper presents the influence of the applied turns ratio correction on the frequency characteristics of the current error and phase displacement of the inductive current transformers evaluated for the transformation of the distorted current.

ALGORITHM FOR DETERMINATION OF BRAKE EFFICIENCY OF INDUSTRIAL RAILWAY TRAINS

The main differences between the operating conditions of industrial railway transport from the main-line ones, which feature the performance of technological transportation, i.e., the transportation of goods within the local boundaries of enterprises (domestic technological transportation), and import (export) of goods to other modes of transport (external transportation). Industrial railway transport plays an important role at mining enterprises, as the working conditions of these enterprises are not constant and getting continuously more complicated during the entire period of field development. In this regard, one of the most important factors in ensuring the train safety is the braking efficiency. The calculation of the braking efficiency of a quarry train is performed according to special rules, and the parameters of the braking process that affect the braking distance are set by coefficients. As an estimated characteristic of braking efficiency for industrial railway transport, the maximum speed is taken, at which the braking distance should be no more than 300 m, regardless of the magnitude of the slope of the railway track. For the first time it is proposed to determine the allowable speed by the iterative method using a correction factor, the choice of which is due to the fact that the relationship between speed and braking distance is described by a quadratic function. The calculation showed that in five iterations the difference between the calculated and normative values of the braking distance of 0.01 m (1 cm) is achieved, which indicates the efficiency effect of the proposed determination procedure. The software allows you to automatically perform calculated studies for a given range of values of the slopes. The results of the train calculation in a specified range of slope values are given, as well as an analytical expression for determining the maximum speed for a given arbitrary slope value. Key words: allowable speed, braking distance, iterative process, correction factor, algorithm.