The gray level aura matrices for textured image segmentation

Inspired by an intuitive analogy that exists between the gray level textures and the miscibility in the multiphase fluids, the aura concept was developed from set theory tools in order to modeling the texture image. The gray level aura matrix (GLAM) has been then proposed to generalize the gray level cooccurrence matrix (GLCM) which remains very popular in the texture analysis. The GLAM indicates how much each gray level is present in the neighborhood of each other gray level. The neighborhood is defined by a structuring element as one used in mathematical morphology. The GLAM is mainly used and studied in synthesis and classification of textures framework but very few works are devoted to the segmentation. The aim of this paper is to exploit the GLAM for the segmentation of textured images. Experiments results over synthetic and real images show the efficiency of the GLAM. The influence of the shape and the size of the structuring element on the segmentation results are also studied.     

Analysis of the semisynchronous carrier sense multiple access onthe bus topology

Consider an arbitrary number of stations equally spaced on a channel configured as a bus topology. The stations access the channel according to the nonpersistent CSMA protocol, which may be with or without collision detection. Users are synchronized to the propagation delay between two adjacent users, and are thus semisynchronized. Such a system with single-buffered users and an exponential backoff strategy, is modeled. The system throughput and the mean delay are evaluated, and it is shown how to obtain the distribution of the packet interdeparture time as well as the packet delay. It is shown that the rescheduling strategy has a profound effect on the station performance, and that it can be used to eliminate the difference between the performance of different stations at any given offered load. The model is also used to accommodate finer synchronization steps, as well as arbitrary topologies     

Investigation of directly suspended droplet micro extraction method for extraction of trihalomethane and halomethane in water samples

Simple and efficient directly suspended droplet micro extraction (DSDME) in conjunction with gas chromatography-electron capture detector (GC-ECD) has been developed for extraction and determination of Halomethane and Trihalomethane from water samples. In this technique a micro drop of n-hexane is delivered to the surface of an aqueous sample while being agitated by a stirring bar in the bulk of solution. Factors relevant to the extraction efficiency were studied and optimized. The optimized extraction conditions were extraction solvent: n- hexane; NaCl concentration: 1 M; solvent extraction volume: 50 μL; stirring rate: 720 rpm and the extraction time: 5 min. The detection limits of the method were in the range of 0.059–0.137 µg L^?1, relative standard deviation (n = 3) range were 0.019–0.048%. A good linearity (r² ≥ 0.997) and a relatively broad dynamic linear range (10–200 µg L^?1) were obtained and recoveries of method were in the range of 97.69–99.51%. Finally, the proposed method was successfully utilized for pre concentration and determination of halo methane in different real samples. Successfully DSDME technique combined with capillary GC-ECD for the analysis of THMs and HMs in the water investigated samples.     

Dearomatization of Diesel by Solvent Extraction: Influence of the Solvent Ratio and Temperature on Diesel Raffinate Properties

To comply with the stringent environmental regulations concerning the quality of fuels the production of ultra low sulfur fuels is obligatory. Consequently, the removal of aromatics from fuels has turned to be a serious issue. This is due to the fact that the presence of aromatics in fuel deters the ultra-low sulfur fuel production. Therefore the researcher’s interest has involved the dearomatization of fuels. As a result of the dearomatization, the quality of fuels improves tremendously. Here, solvent extraction was performed to dearomatize a feedstock sample with 20.1% aromatic and 166 ppm sulfur using acetonitrile. The extraction was performed at low temperature and ambient atmospheric pressure. The aromatic contents were determined via HPLC, while the ASTM methods were employed in other parameters determination. The results showed 72% minimum yield, 8.6% aromatic content, 58–64 cetane index, 73.2 ppm sulfur content, 5.4 viscosity, RI 1.4535, aniline point 82.15, specific gravity 0.824–0.812 with API 40.32–42.88 and flash point 70–78°C. The boiling range of the produced diesel fraction raffinate (172–373°C) that corresponds to C₈–C₂₄ cuts render it a potential candidate for other petrochemical applications.     

Tunable Thermoelectric Performance in Porous Armchair Graphene Nanoribbons as a Function of Strain,Pore Morphology and Temperature

In this paper, the thermoelectric performance of porous armchair graphene nanoribbons under tensile and compressive strain is investigated as a function of pore morphology and temperature. For all the porous structures irrespective of their pore size, the performance improves at a compressive strain of 10%, while for tensile nature, the minimum cut-off strain required for improved thermoelectric figure of merit (ZT) shows an inverse relation with the pore size. In addition, optimal pore shape geometry can yield better performance, even at lower values of strain. Further analysis reveals that tensile strain is not able to improve the performance at low and intermediate temperatures of around 300 K, whereas tensile/compressive strain is effective in enhancing the performance of porous armchair graphene nanoribbons at higher temperatures. Furthermore, the structures are found to be more sensitive to compressive strain than the tensile one since the effect of compressive strain is found to improve ZT more significantly. Our analysis based on Non-Equilibrium Green’s function calculations suggests a possible route for tailoring the functionality of nanomaterials so as to achieve great potentials for thermoelectric applications at various temperatures.     

A Comparison Study Between Pre-Equalization Schemes for Single and Multi Carrier Modulation Systems

In this paper, frequency domain pre-equalization (Pre-FDE) is developed for broadband cyclic prefix-code division multiple access (CP-CDMA) as a single carrier transmission scheme, and for multi carrier-CDMA (MC-CDMA) and orthogonal frequency division multiplexing (OFDM) as multi carrier transmission schemes. A comparison study is held between these schemes and the traditional equalization schemes. Experimental results show that pre-equalization improves significantly the performance of the single and multi carrier communication systems with a very low complexity at the receiver. The comparative study between MIMO pre-equalization for single carrier systems and for multi carrier systems shows that MIMO pre-equalization for single carrier systems outperforms that for multi carrier systems in terms of bit error rate (BER) performance since single carrier transmission has more frequency diversity than multi carrier transmission in the uncoded case.     

Signaling in emerging telecommunications and data networks

This paper discusses the evolution of signaling in modern telecommunications and data networks. It discusses the new capabilities introduced in both narrow-band and broad-band networks and their implications. This paper contrasts work being done in the telecommunications sector of the International Telecommunications Union, ATM Forum, and Internet Engineering Task Force and the motivations for different efforts in each group. The emerging network technologies and services pose a number of challenges in traffic characterization and analysis; these are also highlighted     

Tunable Injection Barrier in Organic Resistive Switches Based on Phase‐Separated Ferroelectric–Semiconductor Blends

Organic non‐volatile resistive bistable diodes based on phase‐separated blends of ferroelectric and semiconducting polymers are fabricated. The polarization field of the ferroelectric modulates the injection barrier at the semiconductor–electrode contact and, hence, the resistance of the comprising diodes. Comparison between the on‐ and off‐current of the switching diodes, with the current measured for semiconductor‐only diodes reveals that the switching occurs between bulk‐limited, i.e., space‐charge‐limited, and injection‐limited current transport. By deliberately varying the HOMO energy of the semiconductor and the work‐function of the metal electrode, it is demonstrated that injection barriers up to 1.6 eV can be surmounted by the ferroelectric polarization yielding on/off current modulations of more than five orders of magnitude. The exponential dependence of the current modulation with a slope of 0.25 eV/decade is rationalized by the magnitude of the injection barrier.     

Network coding-based protection of many-to-one wireless flows

This paper addresses the problem of survivability of many-to-one flows in wireless networks, such as wireless mesh networks (WMNs) and wireless sensor networks (WSNs). Traditional protection schemes are either resource-hungry like the (1+1) protection scheme, or introduce a delay and interrupt the network operation like the (1 : N) protection scheme. In this paper, we present a network coding-based protection technique that overcomes the deficiencies of the traditional schemes. We derive and prove the necessary and sufficient conditions for our solution on a restricted network topology. Then we relax these connectivity requirements and show how to generalize the sufficient and necessary conditions to work with any other topology. We also show how to perform deterministic coding with {0,1} coefficients to achieve linear independence. Moreover, we discuss some of the practical considerations related to our approach. Specifically, we show how to adapt our solution when the network has a limited min-cut; we therefore define a more general problem that takes this constraint into account, which prove to be NP-complete. Furthermore, we discuss the decoding process at the sink, and show how to make use of our solution in the upstream communication (from sink to sources). We also study the effect of the proposed scheme on network performance. Finally, we consider the implementation of our approach when all network nodes have single transceivers, and we solve the problem through a greedy algorithm that constructs a feasible schedule for the transmissions from the sources.