Optimal controller placement in large scale software defined networks based on modified NSGA-II

Software Defined Network (SDN) is an emerging approach to overcome challenges of traditional networks. One particularly important issue in SDN architectures is that of controller placement problem (CPP), i.e., deploying a desired number of controllers within a network while some possibly conflicting requirements have to be fulfilled. A single optimal placement may not be possible and decision makers need to seek for an appropriate trade-off among the metrics. Although an exhaustive evaluation of all possible placements can be practically performed well for small and medium-sized networks, regarding realistic time and resource restrictions, heuristic approaches are required for large-scale networks. Hence, a heuristic called Multi-Start Hybrid NSGA-II (MHNSGA-II) is introduced which yields faster computation times and needs reasonable memory to perform. The obtained results on several topologies extracted from Internet Topology Zoo showed the efficiency of the proposed approach.     

BiTE: a dynamic bi-level traffic engineering model for load balancing and energy efficiency in data center networks

Applied Intelligence - With the recent significant growth of virtualization and cloud services, the data center network (DCN) as the underlying infrastructure is more important. The increasing and...     

Quality changes of fish burgers prepared from deep flounder (Pseudorhombus elevatus Ogilby, 1912) with and without coating during frozen storage (−18 °C)

In the present study, chemical and sensory qualities of fish burgers prepared from deep flounder (Pseudorhombus elevatus Ogilby, 1912) with and without coating (Group A and Group B, respectively) or batter and breading materials were determined during frozen storage at ?18 °C for 5 months. According the statistical results, Total volatile base nitrogen of two groups increased significantly (P < 0.05) but a significant decrease (P < 0.05) was observed at the third month for Group A. Thiobarbituric acid value of Group A decreased significantly (P < 0.05) with the storage time from 1.01 to 0.22, whereas a significant increase (P < 0.05) was observed for Group B from 0.15 to 0.62 at the end of storage time. There were significant differences of pH in either the Group A or Group B between the beginning and end of the storage periods (P < 0.05). Parameters of colour, texture, taste and general acceptability for two groups decreased (P < 0.05) but Group B indicated better scores than Group A at the end of the storage period.     

A novel multicast traffic engineering technique in SDN using TLBO algorithm

In recent years, multicast communication is widely used by network providers to deliver multimedia contents. Quality of service (QoS) provisioning is one of the most important issues while transmitting multimedia contents using multicast. Traditional IP multicasting techniques suffer from reliability, scalability and have limitations to provide appropriate QoS for multimedia applications based on service level agreement (SLA). Nowadays, the advent of software defined networking (SDN), enables network providers to manage their networks dynamically and guarantee QoS parameters for customers based on SLA. SDN provides capabilities to monitor network resources and allows to dynamically configure desired multicasting policies. In this paper, we proposed a novel multicasting technique to guarantee QoS for multimedia applications over SDN. To deliver multimedia contents in an efficient manner, our proposed method models multicast routing as a delay constraint least cost (DCLC) problem. As DCLC problem is NP-Complete, we proposed an approximation algorithm using teaching–learning-based optimization to solve this problem. We evaluated our proposed method under different topologies. Experimental results confirmed that our proposed method outperforms IP multicast routing protocol, and it achieves a gain of about 25% for peak signal-to-noise ratio.     

ZnO 3D flower-like nanostructure synthesized on GaN epitaxial layer by simple route hydrothermal process

The 3D type, flower-like ZnO nanostructures from particle to flower-like or chestnut bur are fabricated on the GaN epitaxial layer substrate through the simple-route hydrothermal process. Structural characterization was made for the ZnO 3D nanostructures synthesized in different pH ranging from 9.5 to 11.0. The growth model was proposed and discussed regarding the fabrication mechanism and morphology of ZnO 3D flower-like nanostructure. The flower-like ZnO is composed of many thin single crystals ZnO nanorods. Bigger and thicker ZnO structure is fabricated with the increase of pH in solution. The enhanced UV emission in the PL measurement and the spectra in the Raman spectroscopy for ZnO–GaN heterojunction material were discussed.     

Band-structure-engineered high-gain LWIR photodetector based on a type-Ⅱ superlattice

The LWIR and longer wavelength regions are of particular interest for new developments and new approaches to realizing long-wavelength infrared(LWIR)photodetectors with high detectivity and high responsivity.These photodetectors are highly desirable for applications such as infrared earth science and astronomy,remote sensing,optical communication,and thermal and medical imaging.Here,we report the design,growth,and characterization of a high-gain band-structure-engineered LWIR heterojunction phototransistor based on type-Ⅱ superlattices.The 1/e cut-off wavelength of the device is 8.0 pm.At 77 K,unity optical gain occurs at a 90 mV applied bias with a dark current density of 3.2×10^-7A/cm².The optical gain of the device at 77 K saturates at a value of 276 at an applied bias of 220 mV.This saturation corresponds to a responsivity of 1284 A/W and a specific detectivity of 2.34×10¹³cm Hz^1/2/W at a peak detection wavelength of~6.8 pm.The type-Ⅱ superlattice-based high-gain LWIR device shows the possibility of designing the high-performance gain-based LWIR photodetectors by implementing the band structure engineering approach.     

Highly regioselective,base-catalyzed,biginelli-type reaction of aldehyde,phenylacetone and urea/thiourea kinetic vs. thermodynamic control

An efficient one-pot regioselective synthesis of various novel 3,4-dihydropyrimidin-2(1H)-one (DHPMs) via a three-component Biginelli-type condensation of aldehyde, phenylacetone and urea/thiourea under two different based-catalyzed conditions is described. In kinetic control path, lithium N, N-diisopropylamide (LDA-20 mol % generated in situ from n-BuLi and diisopropylamine) was used as the base, in tetrahydroforane (THF) as the solvent at 0°C. Thermodynamic control path was run with NaH as the base, in EtOH as the solvent under reflux status. The simple procedure, mild base-catalytic reaction conditions, no column chromatography and good to high yields are important features of this protocol.     

An efficient synthesis of novel sulfonyl[3.3.3]heteropropellanes from sulfonylacetamidines and ninhydrin-malononitrile adduct

The synthesis in good yields of a novel class of sulfonyl[3.3.3]heteropropellanes via a one pot, five-component reaction between sodium arylsulfinates, trichloroacetonitrile, primary amines, and the malononitrile-ninhydrin adduct in H₂O at room temperature has been reported.     

Analysis of antibiotic resistance patterns and detection of mecA gene in Staphylococcus aureus isolated from packaged hamburger

Presence of Staphylococcus aureus, antibiotic resistance pattern and PCR detection of mecA gene in isolated strains were investigated in total of 256 packaged hamburgers in Iran-Tehran. For this purpose we used standard disk-diffusion method and sensitive and specific PCR technique, respectively. Results showed that 25% of samples were positive for S. aureus. Resistance to meticillin, erythromycin, penicillin G, cefazolin, ciprofloxasin, vacomycin and amoxiclave was determined 89%, 20.3%, 18.7%, 15.6%, 14%, 26.6% and 12.5%, respectively. According to the obtained results from PCR analysis of methicillin-resistant S. aureus (MRSA), mecA gene was present in 100% of the resistant isolates, 0% of intermediate-resistance isolates and 25% of susceptible isolates. The results obtained from PCR detection of mecA gene showed high correlation with standard disk diffusion test.