Short- and long-term rheological and chemical characteristics of nanomodified asphalt binder

Due to the special characteristics of nanoparticles, pavement engineers have used nanoparticles as an additive in asphalt pavement to improve pavement performance. This study focuses on characterizing modified asphalt performance using nanoclay particles compared to the unmodified asphalt binder. For this evaluation, 3% of nanoclay particles were added to a neat binder to prepare the nanomodified binder. Then, the modified and unmodified binders underwent a short- and long-term aging process using the Rolling Thin Film Oven (RTFO) and two cycles of Pressure Aging Vessel (PAV). Finally, the Dynamic Shear Rheometer (DSR), Bending Beam Rheometer (BBR), and Fourier-Transform Infrared Spectroscopy - Attenuated Total Reflection (FTIR-ATR) tests were carried out in each aging step to assess and monitor the rutting, fatigue, low-temperature performance, durability, and chemical changes of binders during the aging process. The results of this study proved the enhanced properties and performances of the nanomodified binder compared to the unmodified binder. These results can pave the path with the use of nanomodified binders in the recycling of aged pavement and construction of roads that experience poor weather conditions and high traffic loads.     

An efficient technique for dairy wastewater treatment

The aim of this study was to consider the efficiency of the electro‐Fenton process for organic compound reduction in an industrial dairy effluent. Experiments were conducted to evaluate the effect of several parameters, such as reaction time, pH, H₂O₂/Fe²⁺ molar ratio and volume fraction of H₂O₂ to dairy wastewater (mL/L), on the process performance. The Taguchi technique was applied to investigate the optimum operating conditions. The optimum chemical oxygen demand removal (93.24%) was experimentally obtained at a pH value of 7.58, reaction time of 87.13, current density of 58.5, H₂O₂/Fe²⁺ molar ratio of 3.62 and volume fraction of H₂O₂ to dairy wastewater of 1.39 mL/L.     

Effect of solvent and temperature on the preparation of potassium niobate by hydrothermal-assisted sol–gel processing

In this study the preparation of potassium niobate powder, a material with high electro-optic and nonlinear optical coefficients, by hydrothermal-assisted sol–gel processing from potassium-niobium ethoxide [KNb(OC₂H₅)₆] have been performed. The development of potassium niobate phases by hydrothermal hydrolysis of potassium niobium ethoxide at 100 and 200 °C in ethanol, toluene, and a mixture of benzene and ethanol was pursued by X-ray diffraction. Selected powders obtained from hydrothermal-assisted sol–gel processing were characterized by X-ray powder diffraction, thermal analysis (TGA/DSC), and scanning electron microscopy (SEM). X-ray diffraction results showed that the hydrothermal hydrolysis of potassium-niobium ethoxide in ethanol at 100 and 200 °C results in the formation of cubic phase KNbO₃. Hydrolysis in a mixture of benzene/ethanol and toluene at 200 °C produces an orthorhombic phase KNbO₃, which is a mixture of the potassium deficient phase, K₄Nb₆O₁₇, and cubic and orthorhombic KNbO₃ phases. The potassium niobate powder prepared by the hydrothermal method had the advantage of low weight loss during calcination. SEM micrographs showed that the shape of particles prepared by hydrothermal-assisted sol–gel processing is more uniform when compared with the sample prepared by conventional sol–gel processing.     

A comparative study of slab deformation under heavy width reduction by sizing press and vertical rolling using FE analysis

A detailed comparison between the quality of slabs formed by sizing press and vertical rolling mill is presented. ABAQUS/explicit commercial finite element software with elasto-viscoplastic constitutive model for material is used to study the geometric characteristics and deformation pattern during width reduction in these processes. Finite element models developed for both sizing press and vertical rolling processes are validated by comparing their results with experimental data available in literature. Parametric studies are performed using validated finite element models for sizing press mill to determine the effect of input process parameters such as initial slab width and thickness, width reduction and transfer pitch on the process outputs such as dogbone formation, head and end fishtail profiles, width necking at the leading end of the slab and slab edge quality. Similarly, developed finite element models for vertical rolling are used to investigate the effects of different input parameters on the slab deformation after passing through a vertical rolling stand with the aim of comparing the two width reduction processes. According to the results, benefits and drawbacks of each width reduction method are discussed. The enhancing effect of subsequent horizontal rolling after sizing press and vertical rolling processes on the final slab thickness is also presented.     

Correlating cutting efficiency and debris retention of endodontic files to their design features using AutoCAD measurements

This study aims at evaluating the deformation changes on three types of root canal rotary instruments with different designs; the Pro-Taper Universal, the V-Taper, and the Liberator systems after clinical use. Measurements were made before and after the instruments were used for treating four human root canals by developing stereo-microscopic images for a number of instruments from the three systems at the same position. All images were transformed to AutoCAD to evaluate changes in measurements before and after use. The results showed that the majority of the tested instruments were subjected to significant deformations along the length of the working parts of the instruments. These deformations were only detected by the AutoCAD program but went unnoticed by either visual or microscopic examinations. The results suggest that AutoCAD could be a ground of developing a chair side “computer image analysis program” to predict and justify discarding of a piece before or during operation. In addition, considerations should be given to the material of construction and new approaches of ion implants, such as electro-polishing, that could improve or at least assist in enhancing the wear resistance of the instruments against the dentine surface.     

Oxidation Properties of a Beta-Stabilized TiAl Alloy Modified by Rare Earth Elements

This paper explores the effects of adding rare earth elements (lanthanum or erbium) on the oxidation properties of Ti–43.5Al–4Nb–1Mo–0.1B (TNM) alloy. Isothermal oxidation tests were performed under air atmosphere at 900 and 1000 °C. Mass gain was measured in several steps during the oxidation test, and the oxidized specimens were characterized by XRD and FE-SEM. The results showed that while adding 0.1 at.% rare earth elements (REEs) reduced oxidation rate of the TNM alloy, 0.2 at.% REEs addition increased the mass gain of the alloys. The oxidation curves were fitted by a power-law equation; the results showed that the oxidation kinetic curves of all alloys obeyed parabolic growth kinetics (n = 2). Meanwhile, the activation energy of oxidation was in the range of 40–50 kCal/mol, thereby suggesting that the scale growth was controlled by mass transport in the TiO₂ layer. Also, the results of the scale characterization showed that addition of REEs at low level (e.g., 0.1 at.%) could reduce diffusion rate in the scale. However, addition of the higher amounts of La or Er (e.g., 0.2 at.%) due to the lower valency (+ 3) of these elements, as compared with Ti (+ 4), could lead to the increased anion diffusion, the formation of hillocks in the scale and a rise of the oxidation rate.     

Prediction of geotechnical properties of treated fibrous peat by artificial neural networks

Bulletin of Engineering Geology and the Environment - This paper concentrates on measuring the geotechnical properties of cement peat mixed with different dosages of well-graded sand as filler....     

Using affective human-machine interface to increase the operation performance in virtual construction crane training system: A novel approach

In the construction industry, some progress have been achieved by researchers to design and implement environments for task training using VR technology and its derivatives such as Augmented and Mixed Reality. Although, these developments have been well recognized at the application level, however crucial to the virtual training system is the effective and reliable measurement of training performance of the particular skill and handling the experiment for long-run. It is known that motor skills cannot be measured directly, but only inferred by observing behaviour or performance measures. The typical way of measuring performance is through measuring task completion time and accuracy, but can be supported by indirect measurement of some other factors. In this paper, a virtual crane training system has been developed which can be controlled using control commands extracted from facial gestures and is capable to lift up loads/materials in the virtual construction sites. Then, we integrate affective computing concept into the conventional VR training platform for measuring the cognitive load and level of satisfaction during performance using human's forehead bioelectric-signals. By employing the affective measures and our novel control scheme, the designed interface could be adapted to user's affective status during the performance in real-time. This adaptable user interface approach helps the trainee to cope with the training for long-run performance, leads to gaining more expertise and provides more effective transfer of learning to other operation environments. The detailed methodology of the affective control is presented in the paper. The results and future applications of the proposed method for disabled users, especially from neck down are discussed.