A new nitrite ionic liquid (IL-ONO) as a nitrosonium source for the efficient diazotization of aniline derivatives and in-situ synthesis of azo dyes

A new task-specific nitrite containing ionic liquid derived from the O-nitrosation of N-methyl-N-hydroxybutylimidazolinium chloride was synthesized and used as a source of nitrosonium ion to affect the efficient diazotization of arylamines. The diazonium salts thus obtained were coupled, using standard experimental procedures, to a range of tertiary anilines, phenols and naphthols to afford the requisite azo dyes in good yield. The diazotization and subsequent azo-coupling generated the related azo dyes at 0-5 °C in short reaction times with a simple experimental procedure.     

Design,Synthesis, and Fabrication of Chitosan/Hydroxyapatite Composite Scaffold for Use as Bone Replacement Tissue by Sol–Gel Method

Journal of Inorganic and Organometallic Polymers and Materials - Injuries or bone defects are phenomena that are harmful to human health. In the field of bone scaffold tissue engineering,...     

Effect of carbon nanotube network morphology on thin film transistor performance

The properties of electronic devices based on carbon nanotube networks (CNTNs) depend on the carbon nanotube (CNT) deposition method used, which can yield a range of network morphologies. Here, we synthesize single-walled CNTs using an aerosol (floating catalyst) chemical vapor deposition process and deposit CNTs at room temperature onto substrates as random networks with various morphologies. We use four CNT deposition techniques: electrostatic or thermal precipitation, and filtration through a filter followed by press transfer or dissolving the filter. We study the mobility using pulsed measurements to avoid hysteresis, the on/off ratio, and the electrical noise properties of the CNTNs, and correlate them to the network morphology through careful imaging. Among the four deposition methods thermal precipitation is found to be a novel approach to prepare high-performance, partially aligned CNTNs that are dry-deposited directly after their synthesis. Our results provide new insight into the role of the network morphologies and offer paths towards tunable transport properties in CNT thin film transistors.      

GA and ICA approaches to job rotation scheduling problem: considering employee’s boredom

This paper presents a new model dealing with the job rotation scheduling problem, which is less studied, focusing on human characteristics such as boredom. Existing literature on conceptualizing boredom shows that researchers evaluate boredom in terms of exposure to the same tasks. We developed it to “exposure to similar tasks” and defined its functionality based on the need of assigning jobs with more similarity to each worker in the smallest period of planning which lowers the external interruption effect on worker’s concentration. To address the imbalance between number of jobs and that of workers in many industrial settings, we developed a multi-period imbalance assignment model. The proposed model is to rotate workers during a given planning horizon such that the total cost including assignment and boring cost will be minimized. The applicability of the model is described by presenting some real cases and validated through solving several randomly produced test problems by using Lingo software. Two search algorithms, genetic algorithm (GA) and imperialist competitive algorithm (ICA), designed to conquer the algorithmic complexity of model and their parameters adjusted using Taguchi’s method were used. The efficiency of algorithms is shown, comparing it with Lingo computation times, and it is shown that ICA solutions have better quality than GA solutions as well.     

Thermally Activated Aromatic Ionic Dopants (TA-AIDs) Enabling Stable Doping,Orthogonal Processing and Direct Patterning

Doping plays a critical role in organic electronics, and dopant design has been central in the development of functional and stable doping. In this study, there is departure from conventional molecular dopants and a new class of dopants are reported – aromatic ionic dopants (AIDs). AIDs consist of a pair of aromatic cation and anion that are responsible for molecular doping reaction and charge balancing separately. It is shown that the first AID made from cycloheptatrienyl (tropylium) cation and pentacyanocyclopentadienide anion (PCCp), abbreviated as T-PCCp, can function as an effective p-type dopant to dope polydioxythiophenes. Here, tropylium cation induces the doping reaction while the PCCp anion stabilizes the generated polarons and bipolarons. With T-PCCp, a highly doped (≈120 S/cm) and stable system is achieved up to 150 °C, an orthogonal (sequential)solution processing resulting from the immiscibility of the dopant and the polymer host, and a high-resolution direct micropatterning with laser writing resulted from a thermally activated doping process.     

Study on forcing schemes in the thermal lattice Boltzmann method for simulation of natural convection flow problems

The present study addresses the effect of various schemes for applying an external force term on the accuracy and performance of the thermal lattice Boltzmann method (LBM) for simulation of free convection problems. Herein, the forcing schemes of Luo, shifted velocity method, Guo, and exact difference method are applied by considering three velocity discrete models of D2Q4, D2Q5, and D2Q9. The accuracy and performance of these schemes are evaluated with the simulation of three natural convection problems, namely, free convection in a closed cavity, in a square enclosure with a hot obstacle inside, and the Rayleigh-Benard problem. The obtained results based on the present thermal LBM with different forcing schemes and velocity discrete models are compared with the existing experimental and numerical data in the literature. This comparison study indicates that imposing all employed forcing schemes leads to similar performance for the simulation of free convection problems studied at the middle range of Rayleigh numbers. It is found that the Luo forcing scheme is simple for implementation in comparison with the other three forcing schemes and provides the results with acceptable accuracy at moderate Rayleigh numbers. At higher Rayleigh numbers, however, the Guo scheme is not only numerically stable but a more precise forcing scheme in comparison with the other three methods. It is illustrated that employing the discrete velocity model of D2Q4 has more appropriate numerical stability along with less computational cost in comparison with two other discrete velocity models for simulation of natural convection heat transfer.     

Evaluation of driver drowsiness using respiration analysis by thermal imaging on a driving simulator

In this paper, a new non-intrusive driver drowsiness detection method is introduced based on respiration analysis using facial thermal imaging. Drowsiness is the cause of many driving accidents all over the world. Drivers’ respiration system undergoes significant changes from wakefulness to drowsiness and can be used to detect drowsiness. Current respiration measurement methods are intrusive and uncomfortable making respiration the least measured vital sign during driving. In this paper, a new method is presented based on facial thermal imaging to analyze drivers’ respiration signal non-intrusively. Thirty subjects are tested in a car simulator. They are fully awake at the beginning and experience drowsiness during the tests. The mean and the standard deviation of the respiration rate and the inspiration-to-expiration time ratio are extracted from the subjects’ respiration signal. To detect drowsiness, the Support Vector Machine (SVM) and the K-Nearest Neighbor (KNN) classifiers are used. The Observer Rating of Drowsiness method is used for scoring the drowsiness level and validating the proposed method. The performance and the results of both methods are presented and compared. The results indicate that drowsiness can be detected with the accuracy of 90%, sensitivity of 92%, specificity of 85%, and precision of 91%.

     

Preparation of low-platinum-loading electrocatalysts using electroless deposition method for proton exchange membrane fuel cell systems

One promising preparative method that offers the potential for improved platinum (Pt) dispersion of electrocatalysts is electroless deposition (ED). In this study, the effects of multiwalled carbon nanotubes (MWCNTs) pretreatment and synthesis procedure on properties of the four catalysts, synthesized by ED method, have been considered. The results of energy-dispersive X-ray spectroscopy (EDS), X-ray dot-mapping, X-ray fluorescence (XRF) and cyclic voltammetry (CV) analyses showed that using palladium (Pd) precursor during two-step sensitization-activation coating procedure gives uniform Pt particles distribution on MWCNTs with low aggregation and high specific surface area (∼80 m² g⁻¹). In addition, to investigate the performance of the synthesized catalysts in experimental fuel cell system, thin-film method was used to fabricate the membrane electrode assemblies (MEAs). Obtaining the polarization curves for the fabricated MEAs (Pt loading ∼0.4 mg cm⁻²) and a commercial MEA (ElectroChem, Pt loading ∼1 mg cm⁻²) demonstrated that the catalyst prepared by two-step sensitization-activation coating procedure possesses a good performance despite of its lower Pt content.     

On the self-scheduling of a power producer in uncertain trading environments

This work presents a scenario-based approach to the self-scheduling problem of a price taker power producer in a DA market. It concentrates on three categories of uncertainty including price, forced outage and generation reallocation and analyses their effects on the producer revenue. To tackle the uncertainties a set of price scenarios are so generated that their means and covariance matrix are the same as the base-case scenario. Forced outage and generation reallocation of generator for each price scenario are appropriately modeled through a probabilistic methodology. In this work Downside Risk (DR) is employed as the risk measure which quantifies the downside violations from a specified target. A risk-constrained self-scheduling problem is therefore formulated and solved as a mixed integer linear programming problem. Numerical results for a case study are discussed.     

A hardware/software platform for QoS bridging over multi-chip NoC-based systems

Recent embedded systems integrate a growing number of intellectual property cores into increasingly large designs. Implementation, prototyping, and verification of such large systems has become very challenging. One of the reasons is that chips/FPGAs resources are limited and therefore it is not always possible to implement the whole design in the traditional system-on-a-chip solutions. The state-of-the-art is to partition such systems into smaller sub-systems to implement each on a separate chip. Consequently, it requires interconnecting separate chips/FPGAs. Since Networks-on-Chip (NoCs) have become common interconnection solutions in embedded designs, we propose to bridge NoC-based SoCs enabling a generic multi-chip systems interconnection. In this context, the contribution of this paper is threefold, (i) we explore the NoC protocol stack to determine the best layer for implementing the off-chip bridge, (ii) we propose a generic hardware architecture for the bridge, and (iii) we develop a new software architecture enabling seamless configuration and communication of multi-chip NoC-based SoCs. Finally, we demonstrate performance, i.e., bandwidth and latency, of the bridge in a multi-FPGA platform, while the bridge guarantees QoS of traffic. The synthesis results indicate the implementation area cost of the bridge is only 1% of Xilinx Virtex6 FPGA.