Viscoelastic fatigue resistance of asphalt binders modified with crumb rubber and styrene butadiene polymer

In the present research study, the fatigue behavior of modified asphalt with crumb rubber (CR) and styrene-butadiene-styrene (SBS) are investigated. Each of these additives was mixed with a 85–100 neat bitumen at two different dosages. The time sweep test was used to investigate the viscoelastic fatigue properties of asphalt binders in terms of energy dissipation. Linear amplitude sweep tests were conducted to study the fatigue life of asphalt binders under varying loads based on the concepts of viscoelastic continuum damage mechanics. Results showed that adding CR and SBS can enhance the fatigue resistance of modified asphalts based on the energy approach and viscoelastic continuum damage analysis.     

Evaluation of numerical schemes for capturing shock waves in modeling proppant transport in fractures

In petroleum engineering, the transport phenomenon of proppants in a fracture caused by hydraulic fracturing is captured by hyperbolic partial differential equations (PDEs). The solution of this kind of PDEs may encounter smooth transitions, or there can be large gradients of the field variables. The numerical challenge posed in a shock situation is that high-order finite difference schemes lead to significant oscillations in the vicinity of shocks despite that such schemes result in higher accuracy in smooth regions. On the other hand, first-order methods provide monotonic solution convergences near the shocks, while giving poorer accuracy in the smooth regions. Accurate numerical simulation of such systems is a challenging task using conventional numerical methods. In this paper, we investigate several shock-capturing schemes. The competency of each scheme was tested against onedimensional benchmark problems as well as published numerical experiments. The numerical results have shown good performance of high-resolution finite volume methods in capturing shocks by resolving discontinuities while maintaining accuracy in the smooth regions. These methods along with Godunov splitting are applied to model proppant transport in fractures. It is concluded that the proposed scheme produces non-oscillatory and accurate results in obtaining a solution for proppant transport problems.     

Hybrid composite using recycled polycarbonate/waste silk fibers and wood flour

In this work, hybrid composite materials were made from the combination of waste silk fibers (WSFs) and poplar wood flour (PWF) as reinforcement, recycled polycarbonate (RPC) as polymer matrix, and silane as coupling agent. RPC was obtained from waste compact discs. The effects of fiber type and loading on the mechanical and physical properties of the composites were studied. Experimentally, it was found that the weight content of PWF is a key parameter that would substantially influence the mechanical properties of the samples. The obtained results showed that tensile and flexural strengths and moduli of the composites were significantly enhanced with the addition of biofibers in both types (fiber and flour), as compared with neat RPC. However, the increase in WSFs and PWF contents substantially improved the notched Izod impact strength, but reduced the thermal stability. The significant improvements in mechanical properties of the composites with the incorporation of WSF and PWF were further supported by scanning electron microscopy micrographs. Composites containing more fraction of WSF exhibited higher water absorption (WA) compared with PWF‐filled composites. In addition, composite with higher WSF and PWF (30 wt%) loading showed maximum WA during the whole duration of immersion. POLYM. COMPOS., 37:1667–1673, 2016. © 2014 Society of Plastics Engineers     

Microgrid dynamic responses enhancement using artificial neural network‐genetic algorithm for photovoltaic system and fuzzy controller for high wind speeds

The microgrid (MG) is described as an electrical network of small modular distributed generation, energy storage devices and controllable loads. In order to maximize the output of solar arrays, maximum power point tracking (MPPT) technique is used by artificial neural network (ANN), and also, control of turbine output power in high wind speeds is proposed using pitch angle control technic by fuzzy logic. To track the maximum power point (MPP) in the photovoltaic (PV), the proposed ANN is trained by the genetic algorithm (GA). In other word, the data are optimized by GA, and then these optimum values are used in ANN. The simulation results show that the ANN‐GA in comparison with the conventional algorithms with high accuracy can track the peak power point under different insolation conditions and meet the load demand with less fluctuation around the MPP; also it can increase convergence speed to achieve MPP. Moreover, pitch angle controller based on fuzzy logic with wind speed and active power as inputs that have faster responses which leads to have flatter power curves enhances the dynamic responses of wind turbine. The models are developed and applied in Matlab/Simulink. Copyright © 2015 John Wiley & Sons, Ltd.     

Hybrid classifier for fault location in active distribution networks

This paper presents a fast hybrid fault location method for active distribution networks with distributed generation (DG) and microgrids. The method uses the voltage and current data from the measurement points at the main substation, and the connection points of DG and microgrids. The data is used in a single feedforward artificial neural network (ANN) to estimate the distances to fault from all the measuring points. A k-nearest neighbors (KNN) classifier then interprets the ANN outputs and estimates a single fault location. Simulation results validate the accuracy of the fault location method under different fault conditions including fault types, fault points, and fault resistances. The performance is also validated for non-synchronized measurements and measurement errors.     

Response surface modeling,isotherm, thermodynamic and optimization study of arsenic (V) removal from aqueous solutions using modified bentonite-chitosan (MBC)

Arsenic contamination, a worldwide concern, has received a great deal of attention due to its toxicity and carcinogenicity. In the present study, we focused on the combined application of modified bentonite and chitosan (MBC) for the removal of As(V). Arsenic removal experiments were carried out to determine the amount of As(V) adsorbed as a function of pH (2-8), sorbent dosage (0.1-1.5 g/L), As(V) concentration (20-200mg/L) and time (60-240 min). The system was optimized by means of response surface methodology. The analysis of variance (ANOVA) of the quadratic model demonstrated that the model was highly significant (R²≈97.3%). Optimized values of pH, sorbent dosage, initial As(V) concentration and time were found to be 3.7, 1.40 g/L, 69mg/L, and 167min, respectively. The results reveal that the prepared adsorbent has a high adsorption capacity (122.23mg/g) for As(V) removal. Among the isotherm models used, the Langmuir isotherm model was the best fit for the obtained data. The adsorption kinetics following a pseudo-second-order kinetic model was involved in the adsorption process of As(V). Thermodynamic studies confirmed the spontaneous and endothermic character of adsorption process.     

Design of a Tangible Data Visualisation

In this paper we describe the design of DNA Jewelry, which is a wearable tangible data representation of personal DNA profile data. An iterative design process was followed to develop a 3D form-language that could be mapped to standard DNA profile data, with the aim of retaining readability of data while also producing an aesthetically pleasing and unique result in the area of personalised design. The work explores design issues with the production of data tangibles, contributes to a growing body of research exploring tangible representations of data and     

Capacitive behavior of nanostructured MnO2 prepared by sonochemistry method

Nanostructured manganese dioxide has been successfully prepared by a sonochemical method from an aqueous solution of potassium bromate and manganese sulfate. Changing the proportions of reagents leads either to γ- or layered structures of MnO₂. The capacitive characteristics of the samples were systematically investigated in aqueous electrolytes through means of cyclic voltammetry and chronopotentiometry methods. The electrochemical properties of MnO₂ were strongly affected by the pH of electrolyte employed and this material exhibited ideally capacitive behavior in 0.5 M aqueous Na₂SO₄ solution. A maximum specific capacitance of 344 F g⁻¹ was obtained for the layered structure determined via cyclic voltammetry at a scan rate of 5 mV s⁻¹ in 0.5 M aqueous Na₂SO₄ solution at pH 3.3. Excellent electrochemical reversibility of the materials was also demonstrated.Layered structure MnO₂ showed higher energy density at high power density than the γ-structure material.Impedance spectroscopy studies revealed that charge transfer resistance of the γ-structure oxide has higher value than that of the layered structure.     

Sequestration of glucosinolates by harlequin bug Murgantia histrionica

Murgantia histrionica, the harlequin bug, is an aposematic pentatomid that feeds on toxic crucifer plants. By performing predator trials, we found that the bugs are distasteful to several species of bird predators. Given this, we tested the hypothesis that the bugs sequester toxins from the crucifer plants they feed on for use in defense against predation. We used high-pressure liquid chromatography for analyses and tested if M. histrionica sequesters toxic chemicals from its crucifer diet. We found that M. histrionica sequesters mustard oil glycosides, precursors to zootoxic mephitic nitriles, and that sequestration is characteristic of the plant species fed upon. Glucosinolate titers in M. histrionica bodies were 20–30 times higher than in their guts. We found that cabbage-fed M. histrionica had higher titers of cabbage glucosinolates than bugs that were fed on a cabbage diet and then switched to a diet of garden nasturtium. This indicates that M. histrionica immediately sequesters chemicals from whichever plant it feeds upon. The study shows that M. histrionica can sequester glucosinolates from its host plants for use in defense against predation and that the bugs can retain the glucosinolates for an extended period of time.     

Systematic Approach for Design of Broadband,High Efficiency,High Power RF Amplifiers

This paper demonstrates a systematic approach for the design of broadband, high efficiency, high power, Class‐AB RF amplifiers with high gain flatness. It is usually difficult to simultaneously achieve a high gain flatness and high efficiency in a broadband RF power amplifier, especially in a high power design. As a result, the use of a computer‐aided simulation is most often the best way to achieve these goals; however, an appropriate initial value and a systematic approach are necessary for the simulation results to rapidly converge. These objectives can be accomplished with a minimum of trial and error through the following techniques. First, signal gain variations are reduced over a wide bandwidth using a proper pre‐matching network. Then, the source and load impedances are satisfactorily obtained from small‐signal and load‐pull simulations, respectively. Finally, two high‐order Chebyshev low‐pass filters are employed to provide optimum input and output impedance matching networks over a bandwidth of 100 MHz–500 MHz. By using an EM simulation for the substrate, the simulation results were observed to be in close agreement with the measured results.