ANN-based prediction of surface and hole quality in drilling of AISI D2 cold work tool steel

This paper focuses on artificial neural network (ANN)-based modeling of surface and hole quality in drilling of AISI D2 cold work tool steel with uncoated titanium nitride (TiN) and titanium aluminum nitride (TiAlN) monolayer- and TiAlN/TiN multilayer-coated-cemented carbide drills. A number of drilling experiments were conducted at all combinations of different cutting speeds (50, 55, 60, and 65 m/min) and feed rates (0.063 and 0.08 mm/rev) to obtain training and testing data. The experimental results showed that the surface roughness (Ra) and roundness error (Re) values were obtained with the TiN monolayer- and TiAlN/TiN multilayer-coated drills, respectively. Using some of the experimental data in training stage, an ANN model was developed. To evaluate the performance of the developed ANN model, ANN predictions were compared with the experimental results. It was found that the determination coefficient values are more than 0.99 for both training and test data. Root mean square error and mean error percentage values were very low. ANN results showed that ANN can be used as an effective modeling technique in accurate prediction of the Ra and Re.     

Optimized real options-based approach for government guarantees in PPP toll road projects

The uncertainty associated with future traffic levels in Build–Operate–Transfer toll road projects lead to difficulties in obtaining finance and thus to unsuccessful bids. In order to increase the attractiveness of projects for investors, governments usually provide several types of guarantees such as Minimum Revenue Guarantees (MRGs). In many cases, challenges associated with the valuation of this uncertainty force governments to provide excessive guarantees, placing an increased burden on the public budget. Based on this problem, a real-option-based model is presented for the identification of optimum upper and lower boundaries of compound MRG and Maximum Revenue Cap (MRC) options which establish a fair risk allocation structure. The proposed model uses an optimization approach in which high levels of guarantees in initial years are compensated by the transfer of excess revenues obtained by the private investor in late years. The optimum upper and lower boundaries of compound MRG and MRC options are identified using the proposed model. Results reveal that the emerging net guarantee amount generated by using any pair values of the MRG and MRC that remain in the identified interval not only maintains the attractiveness of project for private investors but also restrains government contingent liabilities. Thus, the identified interval of MRG and MRC enables the structuring of a flexible bargaining environment for both parties.     

Re-employment,Housing Tenure and Squatter Settlements in Turkey: An Empirical Analysis

Although the change in the Turkish economy in the last 14 years is historical, the primary question for public and academic circles remains unanswered: why hasn’t the growth translated into more and better jobs? This paper intends to develop a better understanding about the dragging structural unemployment by investigating the contribution of a possible labour immobility to the unemployment in Turkey. This is the first study that examines the unemployment duration and its relation to residential mobility, more specifically housing tenure in Turkey. It uses the first and only longitudinal survey, Survey of Income and Living Conditions, which became publicly available in 2011. Unlike in developed countries, homeowners in Turkey are often migrants from rural to urban areas living in semi-illegal dwellings. We use this “squatter” effect to reduce the endogeneity problem in estimations, which indicate that residential immobility has a serious impact on unemployment durations in Turkey.     

Identification of boundary heat fluxes in a falling film experiment using high resolution temperature measurements

In this paper, we consider a three-dimensional inverse heat conduction problem (IHCP) in a falling film experiment. The wavy film is heated electrically by a thin constantan foil and the temperature on the back side of this foil is measured by high resolution infrared (IR) thermography. The transient heat flux at the inaccessible film side of the foil is determined from the IR data and the electrical heating power. The IHCP is formulated as a mathematical optimization problem, which is solved with the conjugate gradient method. In each step of the iterative process two direct transient heat conduction problems must be solved. We apply a one step θ-method and piecewise linear finite elements on a tetrahedral grid for the time and space discretization, respectively. The resulting large sparse system of equations is solved with a preconditioned Krylov subspace method. We give results of simulated experiments, which illustrate the performance and tuning of the solution method, and finally present the estimation results from temperature measurements obtained during falling film experiments.     

VARK Learning Style Classification Using Decision Tree with Physiological Signals

Learning style is deemed crucial for different types of age groups. It is essential, especially for individual learning achievement. Learning is a part of cognitive processes affecting the human central nervous system, which can be monitored by using the physiological signals. In this study, physiological signals thus are proposed as key attributes for the classification of learning styles to avoid biased data from completing the questionnaire and promote the real-time response in the classroom environment. More specifically, heart rate and blood pressure signals are chosen for this study. Following the VARK model, the physiological signals of learners are classified with the decision tree into four different types, including visual, aural, read and write, and kinesthetic learners. There are 40 primary school children and 30 university students involved in the whole study. The results show that the proposed factors obtain 85% and 90% classification accuracy for children and university students, respectively. Both heart rate and blood pressure are thus reasonably impacted as the classification attributes.

     

Synthesis and characterization of ferrocene end-capped poly(ε-caprolactone)s by a combination of ring-opening polymerization and “click” chemistry techniques

Ferrocene (Fc) end-capped linear and star-shaped poly(ε-caprolactone)s (PCLs) with different numbers of arms were synthesized by a combination of ring-opening polymerization (ROP) and “click” chemistry techniques in a four-step reaction procedure. In the first step, the polymer backbones were prepared via ROP of the ε-caprolactone (ε-CL) monomer in bulk by employing the compounds with different numbers of hydroxyl groups as the multisite initiators and stannous octoate (Sn(Oct)₂) as the coordination-insertion catalyst. The hydroxyl end-groups of the obtained PCLs were then converted into a bromides and azides consecutively. In the final step, the Fc moiety was attached to the termini of the PCLs using a Cu(I)-catalyzed 1,3-dipolar cycloaddition reaction between the azide end-groups of the PCLs and the acetylene group of ethynylferrocene under ambient conditions. In all cases, the FT-IR and ¹H NMR spectra indicated a successful and quantitative transformation of the desired end-functional groups. The electrochemical properties of the Fc end-capped PCLs were also investigated via cyclic voltammetry (CV).     

Thermoelastic Stability Analysis of Solidification of Pure Metals on a Coated Planar Mold of Finite Thickness

Metallurgical and Materials Transactions B - A theoretical model for investigating the thermoelastic instability/mechanism during pure metal solidification on a coated mold of finite thickness is...     

Extreme learning machine model for water network management

Neural Computing and Applications - A novel failure rate prediction model is developed by the extreme learning machine (ELM) to provide key information needed for optimum ongoing...     

Discrepancies in barrier heights obtained from current–voltage (IV) and capacitance–voltage (CV) of Au/PNoMPhPPy/n-GaAs structures in wide range of temperature

Journal of Materials Science: Materials in Electronics - Au/n-GaAs device was fabricated with an organic PNoMPhPPy thin polymer interfacial layer whose bandgap (Eg) was found as 2.95 eV...     

Risk assessment for sustainability in e-waste recycling in circular economy

Clean Technologies and Environmental Policy - E-waste is a hazardous concept for human health, environment and businesses, and therefore, risk assessment is essential to eliminate or reduce the...