Mode Machining Research Articles

Robustly coordinated operation of a ship microgird with hybrid propulsion systems and hydrogen fuel cells

Increasing global greenhouse gas (GHG) emissions call for new operation strategies towards low-carbon marine transportation. This paper proposes a coordinated operation strategy for a ship micorgird with hybrid propulsion systems (HPSs) to minimize the whole-voyage operation cost within GHG emission limitations. Hydrogen fuel cells are integrated to the ship microgrid for further reduction of GHG emissions. Purchase costs of fuel, hydrogen and electricity and degradation costs of fuel cells (FCs) and batteries are considered in the calculation of whole-voyage operation cost. The proposed coordinated operation strategy consists of two stages. At the pre-voyage scheduling stage, the amount of purchased fuel, hydrogen and electricity, the power of diesel engines (DEs) and FCs, the charging/discharging states of batteries and the motor/shaft-generator modes of electric machines (EMs) are formulated to minimize the whole-voyage operation cost under the worst case of uncertain propulsion and auxiliary power. At the intra-voyage operation stage, power of batteries and EMs is optimized according to the short-leading-time prediction of propulsion and auxiliary power. Above coordinated operation strategy is formulated as a two-stage robust optimization model and solved by a two-level column-and-constraint-generation (C&CG) algorithm. Numerical simulations based on a practical voyage are carried out to validate the effectiveness of proposed strategy.

CEEMD-MR-hybrid model based on sample entropy and random forest for SO2 prediction

As the main output of industrial waste gas, SO2 is harmful to environment and human health. For reducing the hazards to human from SO2, it is urgent and necessary to control the atmospheric pollution. Atmospheric pollution forecasting can provide effective information for controlling atmospheric pollution, so this research proposes a CEEMD-MR-Hybrid model for SO2 forecasting, which employs CEEMD, machine learning models (CNN, PSOSVR, PSOBP) and mode refactor system (MR). The main feature of proposed model is to reconstruct the decomposed series using MR including random forest and sample entropy for hybrid forecasting. Sample entropy can combine decomposed series with similar characteristics by measuring the complexity of distinct decomposed series. Random forest can obtain decomposed sub-sequences high correlated with the original sequence by ranking characteristics importance. Five geographically diverse cities in China are selected to test the validation of the proposed model. Compared with previous CEEMD-RN-Hybrid models, the results of proposed hybrid models have higher consistency with actual data. Therefore, the innovative model can be utilized as an effective model for SO2 forecasting. Taking Shenzhen as an example, the MAPE values of all CEEMD-MR-Hybrid models are smaller than 10% for SO2 forecasting. Therefore, the innovative model provides a machine learning system which can efficiently refactor the decomposition series to improve the accuracy for hybrid model.

Analysis of the Granulometric Composition of the Feedstock Influence on Mechanical Properties of Iron Ore Pellets

The paper investigates the effect of high-temperature roasting and cooling modes of roasted iron ore pellets on their strength and porosity. These characteristics depend on the initial iron ore raw materials properties, the parameters of the raw pellets, the firing temperature, the holding time at this temperature, the heating and cooling rate, and take into account the change in these indicators in connection with the chemical and mineralogical compositions of the pellets. It has been established that the strength of iron ore pellets obtained at the optimum firing temperature depends on the characteristics of the initial finely dispersed iron ore raw material. The relationship between the content of draw rock and the strength of calcined pellets has been revealed. A significant influence of the raw pellets porosity on the strength of the calcined pellets was found. It is shown that the crushing strength of pellets cooled in air is higher than the strength of pellets cooled with water, and a decrease in the final cooling temperature leads to an increase in the strength of the pellets. It is substantiated that the heating rate should not exceed the rate of gas diffusion, and with a decrease in the size of finely dispersed iron ore raw materials, the shrinkage of the pellet layer increases during heating. It is shown that shrinkage appears at temperatures lower than the optimal calcining temperature and insignificantly affects the strength of the pellets. The results obtained can be used to substantiate resource-and-energy efficient operating modes of horizontal-grate machines in ferrous metallurgy.

Universal test bench for studying automatic systems to control operating modes of hydraulic drilling machines and hydraulic equipment

The paper presents hydraulic diagrams of the developed universal test bench for the practical study of designed automation tools, obtaining their output parameters, as well as for adjusting hydraulic liquid flow controllers and analyzing the operability of automatic systems for regulating the operating modes of drilling machines. The operating principle of test bench and technical characteristics of its main hydraulic devices are investigated.

Control loop oscillation detection and quantification using PRONY method of IIR filter design and deep neural network

Generally, the process industry is affected by unwanted fluctuations in control loops arising due to external interference, components with inherent nonlinearities or aggressively tuned controllers. These oscillations lead to production of substandard products and thus affect the overall profitability of a plant. Hence, timely detection of oscillations is desired for ensuring safety and profitability of the plant. In order to achieve this, a control loop oscillation detection and quantification algorithm using Prony method of infinite impulse response (IIR) filter design and deep neural network (DNN) has been presented in this work. Denominator polynomial coefficients of the obtained IIR filter using Prony method were used as the feature vector for DNN. Further, DNN is used to confirm the existence of oscillations in the process control loop data. Furthermore, amplitude and frequency of oscillations are also estimated with the help of cross-correlation values, computed between the original signal and estimated error signal. Experimental results confirm that the presented algorithm is capable of detecting the presence of single or multiple oscillations in the control loop data. The proposed algorithm is also able to estimate the frequency and amplitude of detected oscillations with high accuracy. The Proposed method is also compared with support vector machine (SVM) and empirical mode decomposition (EMD) based approach and it is found that proposed method is faster and more accurate than the later.

Study of a hadron monitor for long baseline neutrino facility

Hadron monitor (HM) plays an important role in inferring or estimating the properties of a neutrino beam by measuring the secondary hadrons in the beam. The HM is also used for the alignment of the primary beam on the production target and for the beam status monitoring during operation. Since HM is permanently placed in the beam line, it has to be robust enough to endure high-level radiation when beam is on. Considering very large dynamic ranges for the beam size and current in different machine modes at the Long Baseline Neutrino Facility (LBNF), an HM in multi-strip secondary electron emission (SEM) type was proposed to meet all the requirements. This paper presents a simulation study of several key issues related to the multi-strip HM, such as energy deposition, signal level estimation and vacuum in a long pipe. A test stand has been setup for measuring the sag in the strips at different temperature that imitates the energy deposition of beam in the strips. The measurements show that with appropriate tension applied, the sag can be easily controlled within a few micrometers.

THE ALGORITHM FOR MONITORING THE ASYMMETRIC MODES OF A THREE-PHASE SYNCHRONOUS MACHINE

The possibilities of monitoring and detecting malfunctions of a synchronous machine are analyzed. The necessity of using the most effective algorithm, which provides the possibility of analyzing a large number of data for monitoring the asymmetric modes of a synchronous machine in the case of phase short circuits is substantiated. An algorithm for monitoring the occurrence of asymmetric modes in a synchronous machine and a block diagram of the system have been developed.

Superior transient and stability performance of voltage regulation by battery-fed bidirectional converter for supporting various operational modes of PMDC machine

This paper presents a systematic procedure to design a voltage controller for achieving superior dynamic performance of a battery-fed bidirectional converter for supporting both motoring and regenerative operations of a permanent magnet direct current (PMDC) machine. In this respect, derivation of a small signal model of overall system is given. Next, the condition for absolute stability is calculated from the model on the basis of the Routh-Hurwitz criterion. Then, gains of the proportional-integral (PI) controller have been tuned using the Ziegler-Nichols tuning chart as per the conventional approach. But, the calculated gains from Ziegler-Nichols tuning chart do not provide satisfactory dynamic performance and sound stability margin under variable voltage conditions. Thus, performance of voltage regulation is deeply investigated and redesign of the voltage controller is emphasised through further mathematical analysis for achieving both superior dynamic performance and significantly stronger stability margin. Superiority of this proposed approach is verified in MATLAB-SIMULINK software based modelling of the physical system and also, in experimental platform.

Superior transient and stability performance of voltage regulation by battery-fed bidirectional converter for supporting various operational modes of PMDC machine

Superior transient and stability performance of voltage regulation by battery-fed bidirectional converter for supporting various operational modes of PMDC machine

Squat and countermovement jump performance across a range of loads: a comparison between Smith machine and free weight execution modes in elite sprinters.

The aims of this study were to: 1) provide and compare the height achieved during Smith machine (SM) and free weight (FW) loaded jumps executed over a wide spectrum of loads (40–120% of body mass [BM]); and 2) test the difference between loaded and unloaded squat jump (SJ) and countermovement jump (CMJ) attempts in ten highly trained male sprinters. On the first visit, athletes performed unloaded SJ and CMJ, loaded SJ with loads corresponding to 40, 60, 80, 100, and 120% BM, and loaded CMJ at 100% BM using an Olympic barbell (FW). On the second visit, they performed loaded SJ and CMJ tests under the same loading conditions on the SM device and, subsequently, a half-squat one-repetition maximum (1RM) assessment. The relative strength (RS = 1RM/BM) of the athletes was 2.54 ± 0.15. Loaded SJ performance was similar between SM and FW, and across all loading conditions. Differences in favour of CMJ (higher jump heights compared with SJ) were superior in the unloaded condition but decreased progressively as a function of loading. In summary, sprinters achieved similar SJ heights across a comprehensive range of loads, regardless of the execution mode (FW or SM). The positive effect of the countermovement on jump performance is progressively reduced with increasing load.

КОРРЕКЦИЯ РЕЖИМА ТОЧЕНИЯ В УСЛОВИЯХ НЕОПРЕДЕЛЕННОСТИ ТЕХНОЛОГИЧЕСКОЙ ИНФОРМАЦИИ С УЧЕТОМ ИЗМЕНЕНИЯ ПАРАМЕТРОВ ПРОЦЕССА ОБРАБОТКИ

The article presents a method for determining the machining mode, which provides for the correction of models linking the output and input parameters of the process according to the current information about the output parameters. A plan has been developed for varying the controlled parameters of the turning process, allowing these parameters to be brought closer to the optimal level. Software has been developed based on this methodology. Using the developed program, studies of the effectiveness of the developed technique in correcting the turning mode calculated according to the formulas of the cutting theory were carried out. The use of the adjusted mode allows to increase the processing performance while ensuring the required quality of the processed part.

Performance assessment of energy efficient and eco-friendly turning of Nimonic C-263: A comparative study on MQL and cryogenic machining

Nimonic C-263 is predominantly used in the manufacturing of heat susceptible intricate components in the gas turbine, aircraft, and automotive industries. Owing to its high strength, poor thermal conductivity, the superalloy is difficult to machine and causes rapid tool wear during conventional machining mode. Moreover, the unpleasant machining noise produced during machining severely disrupts the tool engineer’s concentration, thereby denying a precise and environment friendly machining operation. Hence, close dimensional accuracy, superior machined surface quality along with production economy, and pleasant work environment for the tool engineers is the need of an hour of the current manufacturing industry. To counter such issues, the present work attempts to compare and explore the machinability of two of the most popular machining strategies like minimum quantity lubrication (MQL) and cryogenic machining process during turning of Nimonic C-263 work piece in order to achieve an ideal machining environment. The machining characteristics are compared in terms of surface roughness (SR), power consumption (P), machining noise (S), nose wear (NW), and cutting forces (CF) to evaluate the impact of machining variables like cutting speed (Vc), feed (f), and depth of cut (ap) with a detailed parametric study and technical justification. Yet again, an investigation is conducted to compare both the machining strategies in terms of qualitative responses like chip morphology, total machining cost, and carbon emissions. The study revealed that cryogenic machining strategy is adequately proficient over MQL machining to deliver energy proficient and gratifying work environment for the tool engineers by reducing the cost of machining and improving their work efficiency.

Design of Optical Free-Form Surface Milling Machine Based on Mechanical Shunt and Dynamic Analysis

An optical free-form surface milling machine is designed according to the process characteristics and cutting force of optical components manufacturing. The Z-axis column of the milling machine is designed by a mechanical shunt. In this paper, based on the principle of multibody dynamics (MBD), a virtual prototype (VP) of the optical free-form surface milling machine was established by the ADAMS software. The Z-axis characteristics of the milling machine were simulated and studied, and a modal analysis was carried out to obtain the natural frequencies and vibration modes of the milling machine. The simulation results show that the Z-axis of the milling machine has excellent dynamic characteristics when the gravity balance device is not working. The average torque of the Z-axis motor is 0.5 N·m when the gravity balance device is working, the average torque of the Z-axis motor is 0.1 N·m, and the average torque is reduced by 80%; therefore, the gravity balance device can obviously lower the load of the Z-axis motor, and improve the efficiency of the milling machine.

Eco-friendly precision turning of superalloy Inconel 718 using MQL based vegetable oils: Tool wear and surface integrity evaluation

This work reports on the performance of eco-friendly spray-based approach employing vegetable oils to precision machine nickel based superalloy Inconel 718. Taguchi L9 (33) orthogonal array was used to evaluate two vegetable oils namely sunflower and castor oil for turning operation and their performance was compared with dry machining mode. Three levels of cutting speed (30, 50, 70 m/min.), feed rate (0.168, 0.281, 0.393 mm/rev.) and air pressure (2, 3.5, 5 bar) were used while keeping constant depth of cut (1) mm and spray standoff settings (50 mm). Tool wear, surface roughness and machined surface integrity were taken as response parameters. Tool wear analysis was further supplemented with scanning electron microscopy (SEM). The effects of the input variables on response parameters were quantified by analysis of variance (ANOVA). It was found that feed rate is the most contributing factor for surface roughness with a contribution of 95.71%, 97.86% and 93.19% for MQLSO, MQLCO and dry machining conditions respectively. As for the tool wear, cutting speed is the most contributing factor with a contribution of 76.55%, 80.87% and 69% for MQLSO, MQLCO and dry machining conditions respectively. Minimum tool wear was obtained with sunflower oil with lowest feed rate (0.168 mm/rev.) and cutting speed (30 m/min.) combination. Further insight on worst and least tool wear conditions via SEM images indicate grooving, incidences of adhered material and attrition/chipping to be observable for dry machining condition. On the other hand, lesser incidences of adhered chips and uniform wear which extended up-to the tool nose was observed for least tool wear condition obtained with MQLSO indicting its effectiveness. The minimum values for tool wear (116 μm) and surface roughness (0.43 μm) as obtained with MQLSO, were 26% and 52.09% better (respectively) when compared to the dry machining at same conditions. In the context of surface integrity, a strain hardened layer extending up to the depth of 270 μm was observed at optimum machining parameters. Approximately, 16% higher hardness value was observed closer to the machined surface, than that of bulk material.

Short-term electric load forecasting based on improved Extreme Learning Machine Mode

Aiming at the nonlinear characteristics of short-term electric load series, a short-term electric load forecasting model with improved Extreme Learning Machine (ELM) is proposed. This model is based on the data feature analysis of Ensemble Empirical Mode Decomposition (EEMD) and Long Short-Term Memory (LSTM). EEMD is used to decompose the load sequence into several regular modal components to reduce the error caused by the randomness of the sequence. LSTM and ELM are used to predict the high-frequency and low-frequency components respectively. After using the improved Extreme Learning Machine (ELM), the prediction results of each component are solved. Then the optimal results of power load forecasting are obtained. The results show that the proposed model can judge the overall change trend of the electric load and predict the details of the local change. The average absolute percentage error is 2.24% comparing to 4.78% of the best experiment result of single model, and it has better generality.

Determining the energy efficiency of a resonance single-mass vibratory machine whose operation is based on the Sommerfeld effect

This paper reports determining the energy efficiency of a vibratory machine consisting of a viscoelastically fixed platform that can move vertically, and a vibration exciter whose operation is based on the Sommerfeld effect. The body of the vibration exciter rotates at a steady angular speed while there are the same loads in the form of a ball, a roller, or a pendulum inside it. The load, being moved relative to the body, is exposed to the forces of viscous resistance, which are internal within the system. It was established that under the steady oscillatory modes of a vibratory machine's movement, the loads are tightly pressed to each other, thereby forming a combined load. Energy is productively spent on platform oscillations and unproductively dissipated due to the movement of the combined load relative to the body. With an increase in the speed of the body rotation, the increasing internal forces of viscous resistance bring the speed of rotation of the combined load closer to the resonance speed, and the amplitude of platform oscillations increases. However, the combined load, in this case, increasingly lags behind the body, which increases unproductive energy loss and decreases the efficiency of the vibratory machine. A purely resonant motion mode of the vibratory machine produces the maximum amplitude of platform oscillations, the dynamic factor, the total power of viscous resistance forces. In this case, the efficiency reaches its minimum value. To obtain vigorous oscillations of the platform with a simultaneous increase in the efficiency of the vibratory machine, it is necessary to reduce the forces of viscous resistance in supports with a simultaneous increase in the internal forces of viscous resistance. An algorithm for calculating the basic dynamic characteristics of the vibratory machine's oscillatory motion has been built, based on solving the problem parametrically. The accepted parameter is the angular speed at which a combined load gets stuck. The effectiveness of the algorithm has been illustrated using a specific example

Role of Riboflavin; Curcumin photosensitizers and Ozone when used as canal disinfectant on push-out bond strength of glass fiber post to radicular dentin.

AimTo assess the efficacy of photosensitizers (CP, riboflavin) and gaseous ozone in comparison to the conventional radicular dentin disinfectant (NaOCl) on push-out bond strength (PBS) of PFRC post cemented to radicular dentin. Material and methodHuman single-rooted teeth were collected, steriled implanted in polyvinyl pipes up to a cement-o-enamel junction and de coronated. Cleaning and shaping of the canal were performed using the crown down technique followed by obturation of the canal space. Canal space was prepared using peso reamers and samples were divided into four groups based on types of canal disinfectant protocols. Group 1: Riboflavin+ 17%EDTA; group 2: Curcumin Photosensitizer + 17% EDTA; group 3: Gaseous Ozone disinfection (O3) +17% EDTA and group 4 control 2.5% NaOCl +17% EDTA. Within the canal space, fiber post was cemented and cured, and thermocycled. PBS was evaluated using a Universal testing machine (UTM) and failure modes using a stereomicroscope at 40x magnification. One-way analysis of variance (ANOVA) was used to determine the mean and standard deviation of push-out bond strength (PBS). The Tukey multiple comparison tests (p = 0.05) was used to compare the means of PBS. ResultsThe highest PBS was displayed in group 2 CP+ 17% EDTA at all three root levels, coronal (8.81±0.61), middle (7.77±0.55), and apical (5.25±0.61). The lowest PBS was revealed in group 4, disinfected with 2.5% NaOCl +17% EDTA (control) at coronal (6.12±0.54), middle (5.46±0.84), and apical (3.00±1.88) levels. The most prevailed fracture mode was an adhesive failure (cement-dentin interface). ConclusionRadicular dentin disinfected with PDT using CP, riboflavin, and O3 displayed similar PBS at all root segments. NaOCl is a convenient, traditional, and commonly used disinfectant, and it's effects on PBS is still controversial.

Improving the Efficiency of Electrical Discharge Machining of Special-Purpose Products with Composite Electrode Tools.

The article is devoted to increasing the efficiency of electrical discharge machining of special-purpose items with composite electrode tools. The subject of research is the parameter of the roughness of the processed surface and the work of the electro-discharge machining (EDM) of 40Crsteel in various modes of electrical discharge machining. The aim of the work is to increase the efficiency of the process of copy-piercing electrical discharge machining of parts introduced into the composition of a special-purpose product and the use of electrode tools with the introduction of 20% graphite. Experimental studies were carried out using the method of a full factorial experiment with a subsequent regression analysis. The experiments were carried out using a copy-piercing Smart CNC EDM machine, a tool electrode, and a profile composite electrode. Empirical dependencies were established, reflecting the relationship between the processing modes, productivity, and surface roughness parameter after processing. A theoretical model for calculating the roughness parameter was developed, which makes it possible to predict the quality of the processed surface with a reliability of 10–15%. To ensure the required ratios of the quality of the processed surface at the maximum performance indicators, technological recommendations were obtained, as a result of which a 35% reduction in machine time was achieved when processing the “screw” part with the required indicators of surface quality.

Моделювання та програмний комплекс для дослідження функціонування ежектора в змінних режимах

One of the current directions of development of modern energy-saving and energy-efficient technologies for ship and stationery (including municipal) energy is the use of ejector refrigeration machines, which can be used for air conditioning systems together with an absorption refrigeration machine (cascade cycle) or vapor compressor refrigeration machine as part of cogeneration or trigeneration units. Such circuit solutions can be used together with ensuring the rational organization of work processes in the main elements of the refrigeration machine, in particular in the jet device - ejector, the appropriate design of which, in turn, will further increase the thermal coefficient. Improving the design of the ejector is a rather complex and long process and does not always give positive results. It is primarily because many tests are required on full-scale models. Therefore, computer simulation of the ejector operation at different variable input parameters, considering the geometric characteristics of the flow part and variable mode characteristics during operation is more attractive in terms of finding options for rational (optimal) design. The paper presents the results of software development for modeling hydrodynamic processes in the flowing part of the ejector, considering the variable operating modes of the ejector refrigeration machine. The existing method for calculating the pressure and circulation characteristics of jet devices is used. The developed software complex "RefJet" in the design mode defines the maximum achievable coefficients of ejection of a jet ejector. In the simulation mode - provides determination of the ejection coefficients of the already designed (certain sizes) ejector at variable values of pressure at the inlet and outlet in specific operating conditions, considering its operation at the limit and partial modes. The work of the software package was tested in the development and analysis of circuit solutions of ejector refrigeration machines as part of the heat recovery circuits of three-generation units based on internal combustion engines and gas turbine engines.

Технологическое повышение долговечности внутренних винтовых поверхностей

The methods and some ways of technological improvement of the durability of internal screw surfaces are given. To increase the durability, finishing and strengthening machining with surface plastic deformation and threading with a cutter of a variable average diameter are proposed. The dependences for the specification of machining modes and the results of experimental studies of the screw surface quality parameters and wear resistance of running nuts are given.