Ni-Rhodanine Complex Supported on FSM-16 as Mesoporous Silica Support: Synthesis,Characterization and Application in Synthesis of Tri and Tetrasubstituted Imidazoles and 3,4-Dihydropyrimidine-2-(1H)-Ones

A new, efficient and recoverable heterogeneous catalyst was successfully synthesized by functionalization of mesoporous silica FSM-16. The FSM-16/CPTMS-Rh-     

Highly selective determination of perchlorate by a novel potentiometric sensor based on a synthesized complex of copper

In this paper, a highly selective poly (vinyl chloride) (PVC) membrane electrode based on (1, 9-dibenzyl-1, 3, 7, 9, 11, 15-hexaaza cyclohexa decane) copper(II) perchlorate; [Cu((benzyl)₂[16]aneN₆)](ClO₄)₂; as a synthesized ionophore, for perchlorate-selective electrode is reported. The influence of membrane composition, pH and possible interfering anions were investigated on the response properties of the electrode. The sensor responds to perchlorate ion in linear range from 1.0 × 10^? 6 to 1.0 × 10^? 1 M with a slope ? 59.4 ± 0.3 mV per decade. The limit of detection of the electrode was 4.0 × 10^? 7 M ClO₄^–. Selectivity coefficients indicate a good discriminating ability towards ClO₄^– ion in comparison to other anions. The proposed sensor has a fast response time of about 7 s and can be used for at least 2 months without any considerable divergence in potential. Due to importance of analysis of perchlorate in water samples, this selective electrode was applied as potentiometric sensor in determination of perchlorate ion in real samples.     

Simultaneous Determination of Pentaerythritol Tetranitrate and 2,4,6‐Trinitrotoluene by High Performance Thin Layer Chromatography and Partial Least Squares Regression (PLSR) Method

High performance thin layer chromatography (HPTLC) has been used for the simultaneous determination of pentaerythritol tetranitrate (PETN) and 2,4,6‐trinitrotoluene (TNT). With this aim, the spots were developed on silica gel 60 F₂₅₄ layers with petroleum ether–acetone (2 : 1 v/v). Both PETN and TNT compounds were separated from other constituent materials, and were developed at the same speed, by this solvent system. Then ultraviolet (UV) spectra of these materials were recorded with TLC‐scanner3 of CAMAG Company, and partial least squares regression‐2 (PLSR‐2) method was applied for the calibration and quantitative determination of these materials. The figure of merit (FOM) of this method was determined, and the method was applied for the analysis of an artificial sample.     

Determination of Binary Mixtures of Nitramines by aSpectrophotometric Method Using Partial Least Squares Multivariate Calibration

The UV‐absorption spectra of cyclo‐1,3,5‐trimethylene‐2,4,6‐trinitramine (RDX) and cyclo‐1,3,5,7‐tetramethylene‐2,4,6,8‐tetranitra mine (HMX) are strongly overlapping and do not allow their direct determination without previous separation by conventional methods. A partial least squares method (PLS) in a multicomponent analysis provides a sensitive and accurate technique for the analysis of complex mixtures with strong overlapping spectra. The experimental calibration matrix was designed with 15 samples. The concentration varied between 0.584 μg/ml and 10.220 μg/ml for HMX, and between 0.400 μg/ml and 8.000 μg/ml for RDX. The cross‐validation method was used to select the number of factors. To check the accuracy of the proposed method, the optimized model obtained by using PLS‐2 was applied to the determination of these compounds in industrial samples.     

Calculation of AC Magnetizing Loss of ReBCO Superconducting Tapes Subjected to Applied Distorted Magnetic Fields

In recent years, there are fast-increasing concerns on the utilizations of superconducting rotating electrical machines in different application areas, such as ship propulsion systems, aircraft drivers, and wind turbine generators, since these machines exhibit the merits of high current density, compact design, high power density, light weight, high torque density as well as high efficiency. One of the main limitations in front of the vast use of superconducting tapes in the fabrication of electrical machineries is AC magnetizing loss when tapes are exposed to an external magnetic field, which can decrease the critical current density of wires, as well. In the literature, most of the research works have been done on calculation of the AC magnetizing loss under a pure external magnetic field, while in reality, magnetic flux lines in AC electrical machines are usually distorted with harmonics because of different reasons such as distorted leakage flux, distributed coils of a winding in several slots, cogging fields, mechanical faults, etc. Since these distorted fields contain harmonics, then in this paper, the AC magnetizing loss of superconducting tapes has been electromagnetically modeled and calculated when they are subjected to nonsinusoidally distorted external magnetic fields. The magnetic field dependency of critical current density has been considered in a proposed finite element model. The results have shown that the AC magnetizing loss increases significantly under a distorted applied field compared with a sinusoidal one. In addition, the loss increase depends on the harmonic content which would increases drastically with total harmonic distortion of the applied magnetic field.     

Dynamic modeling and experimental evaluation of olefin copolymerization with vanadium‐based catalysts

In this study, we developed a mathematical model for olefin copolymerization using soluble Ziegler–Natta catalysts in a semibatch reactor to predict the reaction rate and polymer characteristics (i.e., molecular weight, polydispersity, and ethylene content) as functions of the reaction parameters (i.e., time, temperature, pressure, concentrations, and so on) accurately. The proposed model differs from others because it considers the olefin copolymerization as a dynamic process and applies double moments for two reactants (ethylene and propylene) in the presence of hydrogen. To establish the model validity, the copolymerization was performed with VOCl₃? Al₂Et₃Cl₃ systems with hydrogen as a molecular weight controlling agent. The dynamic model was able to reproduce the experimental data within experimental accuracy and accurately demonstrated the fundamental importance of the polymerization variables on the final properties of the polymer material in the copolymerization of ethylene and propylene with Al/V ratios of up to 28 before synthesis. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 3101–3110, 2006     

A reputation system for e-marketplaces based on pairwise comparison

Implementing a reputation system is an effective strategy to facilitate trust and security in an online environment. In addition to that, reputation systems can help online customers through decision-making process. However, in real-world situations, these systems have to deal with plenty of problems and challenges. This paper aims to solve four problems that are common to reputation systems in e-marketplaces, namely the subjectivity of ratings, inequality of transactions, multi-context reputation and dynamic behavior of users. The proposed model starts with the pairwise comparison, which is a powerful tool for removing bias from ratings. Then, we extend the concept of pairwise comparison to contests between users. A pairwise comparison has only a winner and a loser, but we can associate a score differential with a pairwise comparison when we consider it as a match. This score differential is adjusted in a way that three other problems can be solved. We implemented our model in a multi-agent simulation in which real-world data were also incorporated. We compared our model with some of previous reputation systems. Experiments show that our model outperforms previous ones when faced with real-world challenges.     

Separation of Conformers of Nitramines by High Performance Liquid Chromatography (HPLC)

Direct separation has been achieved between two isomers, which are conforming to each other. A conformeric mixture of C_3V and C_S conformers of RDX and α‐ and β‐conformers of HMX have been separated by High Performance Liquid Chromatography (HPLC) using a Nova‐Pak ^RC₁₈ column and MeOH‐H₂O mixtures (50 : 50 to 20 : 80) as mobile phase. The absolute configuration of each separated conformer has been investigated on the basis of the reported heat of formation and dipole moment.     

Scenario-based quasi-static task mapping and scheduling for temperature-efficient MPSoC design under process variation

Nowadays, employing the worst case analysis is the most common approach to provide unified static task mapping–scheduling plans on MPSoCs. Since the whole design space nor a subset of design space are not explored in the worst case methods, these approaches may fail to achieve efficient performance yield. In this paper, we present a temperature-aware quasi-static task mapping–scheduling framework under process variation for hard real-time and periodic systems on MPSoCs. By employing the stochastic optimization and scenario-based approaches, we explore a few representative scenarios in the whole design space of the chip using the probability density function of the problem random variables. Then, we obtain a compact set of near optimal mapping–scheduling of real-time tasks which targets performance-yield maximization and minimization of the expected values of peak temperature. Consequently, considering different chip parameter configurations, we construct the plan set as the solutions that attain the best variation-aware task mapping–scheduling that satisfy the deadline and minimize the temperature. This plan set can readily look up at run time by the system scheduler of the chip to find the proper plan of the tasks based on the run-time parameters. The experimental results demonstrate significant improvements in performance-yield and peak temperature for almost all of the test cases off homogenous and heterogeneous MPSoCs.