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Surface Quality Evaluation of Various Metals After Grinding with Aluminum Oxide Grinding Wheel
Get PDFDifferent metals can respond differently when grinding using the same abrasive grinding wheel, especially in terms of surface quality. In this context, this work aims give a contribution to the metalworking industry by presenting the results of surface finishing after grinding the following metals: VP Atlas steel grade, Gray Cast Iron and two superalloys, Inconel 718 and Ti-6Al-4V. Tests were performed with the aluminum oxide grinding wheel and with following parameters: cutting speed of 37.6 m/s and workspeed of 10 m/min. Two values of depth of cut (15 μm and 30 μm) were tested. The surface roughness (Ra and Rz parameters) were analyzed and SEM images of the machined surfaces were taken and analyzed in order to identify the cutting mechanisms and provide better results discussion. The results showed that the surface roughness increased with the depth of cut; Ra values kept below 0.48 μm for all metals tested. Regarding the machined surface quality, some cracks were observed on the gray cast iron and Ti-6Al-4V surfaces, thereby indicating their relative lower grindability compared to VP Atlas steel under the investigated conditions. No visual thermal damage was observed in the machined surfaces of the samples
The Effect of Atmospheric Pollution on Building Materials in the Urban Environment
Get PDFNowadays atmospheric pollution affects not only the urban environment in general, but building materials, which leads to their corrosion, in particular. The article discusses the regularities of the adhesion process of particulate matter (dust) on the vertical surfaces of buildings and structures, which are made of various building materials. On the basis of experimental studies, regression dependences of the adhesion of urban dust on different vertical surfaces from random determining factors were obtained. Thus, by studying the regularities of pollution of urban environment objects, made of various building materials, it is possible to achieve their preservation, since they demonstrate the architectural and design features of various historical periods of the country's development
The Effect of Rapid Solidification on Microstructure and Corrosion of Advanced Biomaterial Co-Cr-Mo-C Alloy
Get PDFIn this research, the microstructure and corrosion properties of rapidly solidified Co-Cr-Mo-C alloy as an advanced biomaterial alloy were studied. The use of rapid solidification casting method represents significant changes in not only the amount of formed e-HCP phase, which is strongly influenced by rapid solidification, but also in electrochemical behavior and solidified structure. In this research, rapid solidified Co-Cr-Mo-C alloy is studied using OM, SEM, EDS, XRD, and dynamic potentiostate. Co-alloy ingots were melted into an induction furnace filled by argon gas and casted into a V-shape sand and chill copper molds to prepare rapid solidified samples and its properties were measured in different cooling rates. The microstructure examination demonstrating the structure of alloy is mainly consist of columnar dendritic structure with the distribution of carbides within primary and secondary dendrites arms and finer dendritic structure along with modified carbide distribution will be achieved by rapid solidification. This structure will improve alloy’s corrosion behavior and reduces its corrosion rate when it is tested in Ringer’s solution as an electrolyte
Investigation of Roll-to-Roll Gravure Printing for Printed Electronics with Fine Features
Get PDFGravure printing is known to be cost competitive in manufacturing of printed electronic devices due to its capability to mass produce at lower costs. Current standard of gravure printed feature sizes is in a range of around 50 μm down to sub-10 μm, predominantly through small scale setups and specialized engraving. However, reliance on gravure cell design limits the scalability of printing over a large area due to the setup cost. In this study, ink viscoelastic behavior was modified to improve replication of gravure printed features over a large printing area of 300 mm web-width without a reduction in gravure cell dimension. Fine lines were printed using a high viscosity ink with a good replication of the nominal line width. Control over the printed features was performed through the variation of printing speed and the alteration of ink viscosity. The effects of ink viscosity and printing speed on the printed ink particle distribution and size were also examined. New methodologies of characterizing ink transfer were also developed to help understand the ink transfer processes: mass transfer and particle transfer. A deeper understanding of the thixotropic effect and shear recovery behavior of inks was achieved through simulations of shearing conditions
Optimal Portfolio Insurance under Nonlinear Transaction Costs
Get PDFThe minimization of the costs related to portfolio insurance is a very important investment strategy. In this article, by adding the transaction costs to the classical minimum cost portfolio insurance (MCPI) problem, we define and study the MCPI under transaction costs (MCPITC) problem as a nonlinear programming (NLP) problem. In this way, the MCPI problem becomes more realistic. Since such NLP problems are commonly solved by heuristics, we use the Beetle Antennae Search (BAS) algorithm to provide a solution to the MCPITC problem. Numerical experiments and computer simulations in real-world data sets confirm that our approach is an excellent alternative to other evolutionary computation algorithms
Effect of Excess Air Levels on PAHs Content in Smoke During Charcoal Combustion in Grilling Process
Get PDFCharcoal grilling may lead to carcinogenic PAHs contamination of grilled food from incomplete combustion of charcoal. The objective of this study was to determine the effect of complete combustion of charcoal on PAHs content in smoke during the grilling process. Firstly, proximate and ultimate compositions of the charcoal were determined to identify the amount of air required for combustion according to stoichiometry. Different excess air levels consisting of stoichiometric air, 60, 100 and 150% excess air during combustion of charcoal on 16 PAHs released in smoke were studied. Moreover, CO and CO2 concentrations were measured. The use of excess air decreased the emission factor of CO and increased the emission factor of CO2. The 16 PAHs contents in smoke produced from charcoal combusted with stoichiometric air, 60, 100 and 150% excess air were 73.62, 51.78, 27.68 and 19.23 μg/kg dry charcoal, respectively. The use of excess air during charcoal combustion resulted in significantly lower PAHs contents in the smoke. Therefore, the use of excess air during charcoal grilling is one way to reduce the risk of PAHs contamination in grilled food
Forecasting of Summer Monsoon Rainfall over Gangetic West Bengal, India Utilising Intrinsic Mode Functions, Linear and Neural Regression
Get PDFThe South West Monsoon rainfall data of the meteorological subdivision number 6 of India enclosing Gangetic West Bengal is shown to be decomposable into eight empirical time series, namely Intrinsic Mode Functions. This leads one to identify the first empirical mode as a nonlinear part and the remaining modes as the linear part of the data. The nonlinear part is modeled with the technique Neural Network based Generalized Regression Neural Network model technique whereas the linear part is sensibly modeled through simple regression method. The different Intrinsic modes as verified are well connected with relevant atmospheric features, namely, El Nino, Quasi-biennial Oscillation, Sunspot cycle and others. It is observed that the proposed model explains around 75% of inter annual variability (IAV) of the rainfall series of Gangetic West Bengal. The model is efficient in statistical forecasting of South West Monsoon rainfall in the region as verified from independent part of the real data. The statistical forecasts of SWM rainfall for GWB for the years 2012 and 2013 are108.71 cm and 126.21 cm respectively, where as corresponding to the actual rainfall of 93.19 cm 115.20 cm respectively which are within one standard deviation of mean rainfall
Thermodynamic Analysis of Moisture Adsorption of Taraxacum Officinale’ Powder
Get PDFThis work aims to model the adsorption isotherms and study the essential thermodynamic properties of Taraxacum Officinale’ powder during the moisture adsorption phenomenon at three temperatures 30, 40, and 50°C. The results have been determined by the application of the thermodynamics physical principles to the equilibrium data, which are experimentally measured. The estimated values of the isokinetic and harmonic temperatures and the Gibbs free energy change revealed that the sorption process is non-spontaneous and enthalpy driven
Fuzzy Interactive Approach for a Multi-objective Supplier Selection Problem under Robust Uncertainty
Get PDFIn this paper, the authors proposed a multi-objective Mixed Integer Linear Programming (MILP) model for supplier selection problems. The main aim of the system under the investigation is to plan the companies to supply goods to achieve financial benefit by minimizing the total costs and satisfying the customers with on-time delivery and minimizing rejected items. In this case, some restrictions such as multi-product and multi-period conditions, shortage inventory constraints, and discount circumstances simultaneously are considered. Despite these efforts, due to the uncertainty nature of the problem, some parameters are considering as uncertainty data. For this aim, applying robust counterparts for uncertain parameters plays an essential role in real-world applications of this case. It is concluded that the feasibility and optimality properties of the usual solutions of real-world LPs can be severely affected by small changes of the data and that the robust optimization (RO) methodology can be successfully used to overcome this phenomenon
Using Machine Learning Algorithms on Prediction of Stock Price
Get PDFIn this paper, we investigate analysis and prediction of the time-dependent data. We focus our attention on four different stocks are selected from Yahoo Finance historical database. To build up models and predict the future stock price, we consider three different machine learning techniques including Long Short-Term Memory (LSTM), Convolutional Neural Networks (CNN) and Support Vector Regression (SVR). By treating close price, open price, daily low, daily high, adjusted close price, and volume of trades as predictors in machine learning methods, it can be shown that the prediction accuracy is improved