A comparative evaluation of crumb rubber and devulcanized rubber modified binders

One of the most prominent uses of ground tire rubber (GTR) is in rubber-modified asphalt industry. Besides improving performance properties of binders, GTR induces some drawbacks like weak storage stability and inferior low temperature (LT) performance. This study sought to rectify these shortcomings through using devulcanized rubber (DVR) in place of common GTR. Binder performance grading, multiple stress creep and recovery, and storage stability tests were conducted. More resistance against traffic loads at high temperatures was observed as DVR's advantages over GTR, while its weaker LT characteristics and lower storage stability can prevent it from being a viable alternative.     

Effect of temperature on geosynthetic rutting performance in asphalt pavement

In this research study, a 3D finite element model using ABAQUS software is used to evaluate the rutting performance of reinforced asphalt pavement. In this research study, the effects of three types of geosynthetic layers on the optimum location are studied at temperatures of 20°C, 40°C, and 50°C. According to the model analysis, the middle of asphalt layer is determined as the optimized location of geosynthetic layers in the pavement structure. The results showed that the effect of geosynthetic layers on rutting performance increased with increasing elastic modulus of geosynthetic at high temperature of pavement.     

3D FEM analysis,dynamic modeling,and performance assessment of transverse flux PMSG for small‐scale gearless wind energy conversion systems

The transverse flux permanent magnet synchronous generator has a great potential for use in direct‐drive wind energy conversion systems due to its large pole numbers, high torque, and power density. This research work develops dynamic model of a single‐side transverse flux permanent magnet synchronous generator for use in a small‐scale gearless wind energy conversion system. For acquiring the parameters of the considered generator, required for dynamic modeling, 3D finite element model of the machine is developed and analyzed in both magneto‐static and transient modes. Field‐oriented control approach is employed for tracking maximum power point from the variable wind speed. The simulation results illustrate an accurate response of the system to the wind speed variation and proper performance of the developed dynamic model and control approach of the system. Copyright © 2015 John Wiley & Sons, Ltd.     

Effect of Channel Estimation Error on Time Reversal UWB Communication System

In this paper, effects of channel estimation error on time reversal (TR) UWB systems are investigated. In time reversal, a signal is prefiltered by using a time reversed complex conjugate of the channel impulse response as a transmitter prefilter. To investigate the effect of channel estimation error, an error function is added to TR-UWB prefilter. Analytical and simulation results show that channel estimation error degrade the performance. The signal-to-interference plus noise ratio decreases with increasing error variance. It is shown that the channel performance is degraded about 0.5 dB in CM1 and 1.3 dB in CM4 channel.     

System specification with the SpecCharts language

The SpecCharts language, which builds on VHDL to meet the unique requirements of system-level specification and design, is described. With an underlying model of behavioral hierarchy, SpecCharts modeling constructs enable designers to capture system specifications simply and precisely. SpecCharts constructs facilitate system-level design tasks by permitting high-level communication, maintaining information, and allowing design modification at an easy-to-comprehend level. The results of system-level design tasks are reflected in a modified SpecCharts, enabling the designer to evaluate the quality of each step. A detailed example demonstrates the use of SpecCharts     

Distance transform algorithm for measuring nanofiber diameter

This paper describes a new distance transform method used for measuring fiber diameter in electrospun nanofiber webs. In this algorithm, the effect of intersection is eliminated, which brings more accuracy to the measurement. The method is tested by a series of simulated images with known characteristics as well as some real webs obtained from electrospinning of PVA. Our method is compared with the distance transform method. The results obtained by our method were significantly better than the distance transform, indicating that the new method could successfully be used to measure electrospun fiber diameter.     

A mathemathical model for the calculation of the concentration at the outlet of an ozone generator

A mathematical model was generated to predict the composition of the outlet gas of ozone generators. In order to make the modelling possible it was important to predict the occurrence time and the exact location of each individual discharge zone. This was done by connecting a specially constructed ozone generator, which would locate the discharge zones, to a nanosecond pulse generator which would impose regular occurrence times for discharge columns. The experimental and theoretical outlet concentrations of this ozone generator were compared. The result was an excellent match which justified the assumptions made in the model. The mathematical model was also used to study the effect of different factors affecting the production of ozone.     

Synthesis and characterization of exfoliated poly(styrene‐co‐methyl methacrylate) nanocomposite via miniemulsion atom transfer radical polymerization: an activators generated by electron transfer approach

Exfoliated poly(styrene‐co‐methyl methacrylate) nanocomposites were synthesized using activators generated by electron transfer for atom transfer radical polymerization (AGET ATRP). Miniemulsion polymerization was used for its abundant advantages to encapsulate inorganic materials and eliminate organic solvents from products for environmentally friendly purposes. Cetyltrimethylammonium bromide (CTAB) as a cationic surfactant, which is an effective surfactant at higher temperatures, was used to stabilize the miniemulsion system. Successful miniemulsion AGET ATRP was carried out by using 4,4'‐dinonyl‐2,2'‐bipyridine (dNbPy) as a hydrophobic ligand. Formation of monodispersed droplets and particles with sizes in the range of 200nm was examined by dynamic light scattering (DLS). Conversion and molecular weight study were also carried out using gravimetry and gel permeation chromatography, respectively. By adding clay content, a decrease in the conversion and molecular weight of the nanocomposites are observed. However, an increase in the PDI values of nanocomposites was observed by the addition of nanoclay content. Thermogravimetric analysis results demonstrate that thermal stability of all the nanocomposites in comparison with the neat copolymer increases. Differential scanning calorimetry results show that T_g decreases by increasing clay content. Monodisperse distribution of spherical shape particles with sizes in the range of ∼ 200 nm was demonstrated by using scanning electron microscopy images of nanocomposite containing 1 wt% of nanoclay, which is more compiled with DLS results. Transmission electron microscopy results shows well‐dispersed exfoliated clay layers in the polymer matrix of PSMNM 1, which is coincidence with X‐ray diffraction data. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers     

Application of the PSO–SVM model for recognition of control chart patterns

Control chart patterns are important statistical process control tools for determining whether a process is run in its intended mode or in the presence of unnatural patterns. Accurate recognition of control chart patterns is essential for efficient system monitoring to maintain high-quality products. This paper introduces a novel hybrid intelligent system that includes three main modules: a feature extraction module, a classifier module, and an optimization module. In the feature extraction module, a proper set combining the shape features and statistical features is proposed as the efficient characteristic of the patterns. In the classifier module, a multi-class support vector machine (SVM)-based classifier is proposed. For the optimization module, a particle swarm optimization algorithm is proposed to improve the generalization performance of the recognizer. In this module, it the SVM classifier design is optimized by searching for the best value of the parameters that tune its discriminant function (kernel parameter selection) and upstream by looking for the best subset of features that feed the classifier. Simulation results show that the proposed algorithm has very high recognition accuracy. This high efficiency is achieved with only little features, which have been selected using particle swarm optimizer.