Designing resilient networks using multicriteria metaheuristics

The paper deals with the design of resilient networks that are fault tolerant against link failures. Usually, fault tolerance is achieved by providing backup paths, which are used in case of an edge failure on a primary path. We consider this task as a multiobjective optimization problem: to provide resilience in networks while minimizing the cost subject to capacity constraint. We propose a stochastic approach, which can generate multiple Pareto solutions in a single run. The feasibility of the proposed method is illustrated by considering several network design problems using a single weighted average of objectives and a direct multiobjective optimization approach using the Pareto dominance concept.     

Smart antenna design for high‐speed moving vehicles with minimum return loss

The Internet of Things (IoT) is a connection amongst people and applications to another dimension of machine‐to‐machine communication. IoT scenario is unequivocally related with the development of the advancement of wireless sensor systems (WSNs) and radio‐frequency identification (RFID) frameworks. Owing to the technological advances around the world, energy demand is increasing exponentially. Energy proficiency has turned out to be one of the real worries in the present life that essentially influence every single human action. In communication system, return loss is a major issue for transmission process. Owing to return loss, a huge amount of power consumption occurs. This phenomenon is contemporary with transmission process, and it will initiate a serious problem for high‐speed moving substance like aircraft, rockets, and spaceship. To overcome this problem, a four‐element cylindrical antenna (conformal) array with better axial radiation is proposed. The four U‐shaped slots are uniformly wrapped around on a cylindrical surface, which produces tilted radiation. To enhance the axial radiation, four conformal elements are reefed by a one‐ to four‐microstrip feed network. The proposed conformal design has a bandwidth of 200 MHz (narrow bandwidth) at the center frequency of 3.9 GHz, covering the range of 3 to 3.9 GHz, with the gain of 4.9 dBic, and can be suitable for unmanned aerial vehicles (UAV), wireless avionics intra‐communication (WAIC), and so forth. The proposed design is low profile and can be used for high‐speed avionic applications. Finally, machine learning technique is explored to design a model for a smart antenna with optimistic parameters to reduce return loss and enhance the transmission rate.     

Highly efficient alkene epoxidation and aziridination catalyzed by iron(II) salt + 4,4',4'-trichloro-2,2':6',2'-terpyridine/4,4'-dichloro-4'-O-PEG-OCH3-2,2':6',2'-terpyridine

"Iron(II) salt + 4,4',4'-trichloro-2,2':6',2'-terpyridine" is an effective catalyst for epoxidation and aziridination of alkenes and intramolecular amidation of sulfamate esters. The epoxidation of allylic-substituted cycloalkenes achieved excellent diastereoselectivities up to 90%. ESI-MS results supported the formation of iron-oxo and -imido intermediates. Derivitization of Cl 3terpy to O-PEG-OCH 3-Cl 2terpy renders the terpyridine unit to be recyclable, and the "iron(II) salt + 4,4'-dichloro-4'- O-PEG-OCH 3-2,2':6',2'-terpyridine" protocol can be reused without a significant loss of catalytic activity in the alkene epoxidation.     

Front Cover: Enhancement of dielectrophoresis-based particle collection from high conducting fluids due to partial electrode insulation

Dielectrophoresis (DEP) is a successful method to recover nanoparticles from different types of fluid. The DEP force acting on these particles is created by an electrode microarray that produces a nonuniform electric field. To apply DEP to a highly conducting biological fluid, a protective hydrogel coating over the metal electrodes is required to create a barrier between the electrode and the fluid. This protects the electrodes, reduces the electrolysis of water, and allows the electric field to penetrate into the fluid sample. We observed that the protective hydrogel layer can separate from the electrode and form a closed domed structure and that collection of 100 nm polystyrene beads increased when this occurred. To better understand this collection increase, we used COMSOL Multiphysics software to model the electric field in the presence of the dome filled with different materials ranging from low-conducting gas to high conducting phosphate-buffered saline fluids. The results suggest that as the electrical conductivity of the material inside the dome is reduced, the whole dome acts as an insulator which increases electric field intensity at the electrode edge. This increased intensity widens the high-intensity electric field factor zone resulting in increased collection. This informs how dome formation results in increased particle collection and provides insight into how the electric field can be intensified to the increase collection of particles. These results have important applications for increasing the recovery of biologically-derived nanoparticles from undiluted physiological fluids that have high conductance, including the collection of cancer-derived extracellular vesicles from plasma for liquid biopsy applications.     

Rapid Estimation of Octanol–Water Partition Coefficient for Triazole Fungicides by MEKC with Sodium Deoxycholate as Surfactant

A rapid estimation of octanol–water partition coefficient (log P _ow) was developed for triazole fungicides by micellar electrokinetic chromatography (MEKC). Five standard compounds with known log P _ow values from 2.9 to 4.3 (cyproconazole, bromuconazole, epoxiconazole, bitertanol and difenoconazole) were used for constructing the calibration curve of the log P _ow against the MEKC retention factor, log k. A linear relationship was achieved between log P _ow and log k, in the MEKC system containing 40 mM sodium deoxycholate (SDC) and 4 mM borate buffer at pH 9.3, with a correlation of determination, r ² = 0.9905. The log P _ow values of four test compounds of triazole fungicides (triadimenol, myclobutanil, propiconazole and penconazole) were calculated based on the log k values measured by MEKC and the slope and intercept of the calibration curve. This MEKC method can give good estimation of the log P _ow of the four test compounds of triazole fungicides with the differences between the literature log P _ow values and estimated log P _ow from the MEKC method were from 0.15 to 0.23 log units.     

Hardness and Young's modulus of transcrystalline polypropylene by Vickers and Knoop microindentation

A study of the anisotropic microhardness and Young's modulus of transcrystalline isotactic polypropylene grown from the surface of high modulus carbon fibers is described. Static microindentation experiments were performed with Knoop and Vickers tips. The Young's moduli of the transcrystalline region were estimated from Knoop microindentation data by using a method recently developed in our laboratory. Data for the different lamellar directions were generated using the Knoop tip, which is sensitive to material anisotropy. We found that the hardness and Young's modulus of the transcrystalline layer are higher by up to 30% when the longer diagonal of the probing Knoop tip is perpendicular to the transcrystalline growth direction, compared to when the diagonal is parallel to that direction. © 1999 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 37: 523–530, 1999     

Experimental low energy values of CH4 transitions near 1.33 μm by absorption spectroscopy at 81 K

The high resolution absorption spectrum of methane has been recorded at liquid nitrogen temperature by direct absorption spectroscopy between 1.36 and 1.30 μm (7351-7655 cm⁻¹) using a cryogenic cell and a series of distributed feed back (DFB) diode lasers. The investigated spectral range corresponds to the high energy part of the icosad dominated by the ν₂+2ν₃ band near 7510 cm⁻¹. The positions and strengths at 81 K of 3473 transitions were obtained from the spectrum analysis. The minimum value of the measured line intensities (at 81 K) is on the order of 10⁻²⁶ cm/molecule, i.e. significantly lower than the intensity cut off of the HITRAN database in the region (4×10⁻²⁵ cm/molecule at 296 K). From the variation of the line strength between 81 and 296 K, the low energy values of 1273 transitions could be determined. They represent 69% and 81% of the absorbance in the region at 296 and 81 K, respectively. The obtained results are discussed in relation with the few rovibrational assignments previously reported in the region.