Synthesis of some novel antioxidant and anticorrosive additives for Egyptian gasoline motor oils

2‐Methyl‐benzo[d][1,3]oxazin‐4‐one ( 1 ) was used as a key intermediate for the synthesis of different benzoxazinone and quinazolinone derivatives. In order to evaluate the applicability of the synthesised benzoxazinones and quinazolinones as antioxidant additives for lube oil, these antioxidant additives decomposed the alkyl peroxide radicals and/or alkyl hydrogen peroxides to produce esters, ketone and hydroxy compounds rather than carboxylic acids. The compounds that showed antioxidant efficiency were tested as corrosion inhibitors using three types of metals: Cu, Al and Fe. Copyright © 2011 John Wiley & Sons, Ltd.     

Improved target detection with ultra wideband radars using efficient coded waveforms

Performance evaluation of ultra wideband (UWB) radar in terms of target detection, resolution, recognition, and clutter and interference rejection depends on the structure of the radar waveform. The chirp waveform, which is commonly used in radar applications, has high time sidelobes in the level of ??20 dB. Another limitation is the excessive range-Doppler cross coupling, which occurs, when the Doppler shifted signal is correlated with the original signal, and this gives a different time of arrival. In this paper, a wideband chirp-Gaussian waveform with phase coding is proposed to overcome these drawbacks. A mathematical formulation for the proposed waveform is introduced. Plots of the power spectral density, delay-Doppler Ambiguity Function (AF), and autocorrelation function are presented. These plots reveal that the chirp-Gaussian waveform reduces the sidelobe level to ??55 dB, and its AF has the property of low-level sidelobes resembling the “thumbtack” AF, the ideal ambiguity function for high resolution radar.     

Efficient SVD speech watermarking with encrypted images

This paper presents a new approach for speech signal watermarking using encrypted watermarks. The objective of this approach is to increase the degree of security of speech watermarking. In the proposed framework, watermark embedding is implemented with singular value decomposition due to its robustness to attacks. Moreover, two encryption schemes are tested for watermark image encryption; chaotic encryption due to its permutation nature and data encryption standard (DES) due to its diffusion nature. Overall and block-by-block watermarking scenarios are tested and compared for speech signal watermarking. Different modes of operation of the DES are investigated for watermark image encryption. These modes are the electronic code book, cipher block chaining, cipher feedback, and output feedback (OFB) modes. Simulation results reveal that the DES with OFB mode and the chaotic Baker map encryption make the system less sensitive to attacks with good quality of extracted watermarks.     

An efficient method for image forgery detection based on trigonometric transforms and deep learning

Multimedia Tools and Applications - Image forgery detection is the basic key to solve many problems, especially social problems such as those in Facebook, and court cases. The common form of image...     

Thermal radiation effects on oscillatory squeeze flow with a particle-fluid suspension

The study of squeezing flow has attracted considerable interest in recent years for its important applications in industrial, biomedical and engineering domains such as fibre-reinforced, cell squeeze technology. The aim of this study is to analyze the flow and heat transfer of a squeezed particle fluid with thermal radiation effects between parallel plates. The governing partial differentials are reduced to ordinary differential equations by a similarity transformation and solved numerically using the finite difference method. The effects of different physical parameters on the velocity and temperature profiles are discussed with the help of graphs coupled with comprehensive discussions. The results indicate that the thermal radiation parameter enhanced the fluid and particle temperature distribution and for the plate oscillation case, reverse flow is observed. To show the biological relevance of the analysis, the results obtained analyzed the influence of the squeezed artery wall on the suspension blood flow for normal and diseased blood using the experimental data from the published literature. Finally, a comparison between the present similarity solutions and previously published results shows the accuracy of the current results.     

Performance analysis of mid-symbol antenna transition spatial modulation approach over Rician fading channels

Wireless Networks - The mid-symbol antenna transition (MAT) approach reduces the number of transmitter antennas in spatial modulation (SM) systems. This paper studies the performance of MAT...     

Cooperative Space–Time Coding with Amplify-and- Forward Relaying

Cooperative diversity using distributed space-time codes has been recently proposed to form virtual antennas in order to achieve diversity gain. In this paper, we consider a multi-relay network operating in amplify-and-forward (AAF) mode. Motivated by protocol III presented in (Nabar et al. 2004), we propose a cooperative diversity protocol implementing space–time coding for an arbitrary number of relay nodes when the source-destination link contributes in the second phase. We consider the use of real-orthogonal and quasi-orthogonal designs of space–time codes as they give better performance than random linear-dispersion codes. The pairwise error probability (PEP) has been derived and the theoretical analysis demonstrates that the proposed protocol achieves a diversity of order N + 1, where N is the number of relay nodes. No instantaneous channel state information is required at the relay nodes. The optimum power allocation that minimizes the PEP is obtained with numerical and theoretical analysis. The aggregate system power constraint is considered in the optimization. Simulation results demonstrate an improvement over the existing orthogonal protocols for different source-destination channel conditions. The results also show that the proposed scheme is robust to the channel estimation errors     

The Evaluation of Some Heterocycles as Antioxidant Additives for Lubricating Oils

Abstract

2-Phenyl-4-thienylidene-2-oxazolin-5-one I was prepared and reacted with 2-aminothiazole, p-aminophenol, and p-aminoacetophenone in the presence of acetic acid containing catalytic amounts of freshly fused sodium acetate to give the corresponding imidazolone derivatives II, III, and IV, respectively. A Claisen reaction of IV with ethylacetate gave the corresponding imidazolone V, which on reaction with phenylhydrazine in ethanol afforded the corresponding pyrazolinoimidazolone VI. On the other hand, I reacted with o- and p-phenylenediamines in ethanol and yielded the corresponding o- and p-aminophenylcarboxamide of α-phenyl carboxamido-β-thiophenoacrylic acids VII and VIII, respectively. The prepared products were evaluated as antioxidant additives for Egyptian lube oils. Some of these products showed good results.     

A chaotic interleaving scheme for continuous-phase modulation-based orthogonal frequency-division multiplexing systems

In this article, we propose a chaotic interleaving scheme for continuous-phase modulation-based orthogonal frequency-division multiplexing (CPM-OFDM) systems. The idea of chaotic maps randomisation (CMR) is exploited in this scheme. CMR generates permuted sequences from the sequences to be transmitted with lower correlation among their samples, and hence a better Bit Error Rate (BER) performance can be achieved. The proposed CMR-CPM-OFDM system combines the advantages of frequency diversity and power efficiency from CPM-OFDM and performance improvement from chaotic interleaving. The BER performance of the CPM-OFDM system with and without chaotic interleaving is evaluated by computer simulations. Also, a comparison between chaotic interleaving and block interleaving is performed. Simulation results show that, the proposed chaotic interleaving scheme can greatly improve the performance of CPM-OFDM systems. Furthermore, the results show that the proposed chaotic interleaving scheme outperforms the traditional block interleaving scheme for CPM-OFDM systems. The results show also that, the proposed CMR-CPM-OFDM system provides a good trade-off between system performance and bandwidth efficiency.