A Comparative Analysis of Evolutionary Algorithms for Synthesis of Scanned Linear Array of Mutually Coupled Parallel Dipole Antennas

This paper presents a comparative analysis of threeevolutionary algorithms, namely, Backtracking Search Algorithm,Cuckoo Search Algorithm and Artificial Bee Colony Algorithms forsynthesis of a scanned linear array of uniformly spaced parallel halfwavelength dipole antennas. Here, antenna parameters, namely SideLobe Level, reflection coefficient and wide null depth are taken intoconsideration for comparison between algorithms. In addition to it,statistical parameters, namely best fitness value, mean and standarddeviation of the fitness values obtained from algorithms are compared.Mutual coupling that exists among the antenna elements is included inobtaining radiation patterns and the self-impedances along with themutual impedances are calculated by induced Electro-Motive Forcemethod. Two different examples are shown in this paper to validate theeffectiveness of the utilized approach. Although, this approach is appliedto a linear array of dipole antennas; this can be utilized for other arraygeometries as well

Aerosol optical properties and composition over a table top complex mining area in a monsoon trough region

Aerosol physiochemical properties over a varied mining plateau region at the eastern end of a monsoon trough are reported for the first time and analyzed at different time scales. Aerosol optical depth (single scattering albedo, SSA) is found to be 0.49 (0.9) in pre-monsoon, 0.4 (0.94) in monsoon, 0.46 (0.92) in post-monsoon, and 0.36 (0.89) in winter, with an annual mean of 0.43 (0.91). The volume-size distribution is tri-modal, with 0.02 (ultra-fine), 0.2 (accumulation) and 7 (coarse) µm, but with seasonal signatures. The angstrom exponent (AE) varies along with the AOD, especially in winter, although they are inversely related to each other during monsoons; the increase in size may be due to the effect of humidity. AODbc varies between 13.4%–4.7% of the total aerosols, with the highest contribution in March, when forest burning in the north east is at its peak. BC is the lowest in July, the mid monsoon month with the minimum biomass burning and brick-kiln activities. It is likely that the interactions of various minerals and intermittent rains help keep the aerosol size in a mixed state with regard to the relation between AE and AOD, although more work is needed to confirm this. The chemical composition of aerosols is derived from an aerosol chemical model based on the measured amount of black carbon and the assumed components

Aerosol optical properties and composition over a table top complex mining area in the Monsoon trough region

Aerosol physiochemical properties over a varied mining plateau region at the eastern end of a monsoon trough are reported for the first time and analyzed at different time scales. Aerosol optical depth (single scattering albedo, SSA) is found to be 0.49 (0.9) in pre-monsoon, 0.4 (0.94) in monsoon, 0.46 (0.92) in post-monsoon, and 0.36 (0.89) in winter, with an annual mean of 0.43 (0.91). The volume-size distribution is tri-modal, with 0.02 (ultra-fine), 0.2 (accumulation) and 7 (coarse) µm, but with seasonal signatures. The angstrom exponent (AE) varies along with the AOD, especially in winter, although they are inversely related to each other during monsoons; the increase in size may be due to the effect of humidity. AODbc varies between 13.4%–4.7% of the total aerosols, with the highest contribution in March, when forest burning in the north east is at its peak. BC is the lowest in July, the mid monsoon month with the minimum biomass burning and brick-kiln activities. It is likely that the interactions of various minerals and intermittent rains help keep the aerosol size in a mixed state with regard to the relation between AE and AOD, although more work is needed to confirm this. The chemical composition of aerosols is derived from an aerosol chemical model based on the measured amount of black carbon and the assumed components. These components are selected based on back trajectories and earlier reports from the region. Their concentrations are adjusted by constraining the model output AOD and SSA to match (±2% @ 500 nm) that observed by a sun-sky radiometer. The chemical compositions of the winter and post-monsoon months are similar, while pre-monsoon period has more coarse mode minerals, and the monsoon period has more sea-salt (accu.). The component mass concentrations were grouped into various size bins based on their modal radii, and the results indicate that PM1 is at its maximum in winter whereas PM2.5 is highest in the post-monsoon period. Monsoons leads to the effective washout of 2.5–10 µm sized particles

Approximation of excitonic absorption in disordered systems using a compositional component weighted CPA

Employing a recently developed technique of component weighted two particle Green's functions in the CPA of a binary substitutional alloy $A_cB_{1-c}$ we extend the existing theory of excitons in such media using a contact potential model for the interaction between electrons and holes to an approximation which interpolates correctly between the limits of weak and strong disorder. With our approach we are also able to treat the case where the contact interaction between carriers varies between sites of different types, thus introducing further disorder into the system. Based on this approach we study numerically how the formation of exciton bound states changes as the strengths of the contact potentials associated with either of the two site types are varied through a large range of parameter values.Comment: 27 pages RevTeX (preprint format), 13 Postscript figure file

Theory of optical spectra of polar quantum wells: Temperature effects

Theoretical and numerical calculations of the optical absorption spectra of excitons interacting with longitudinal-optical phonons in quasi-2D polar semiconductors are presented. In II-VI semiconductor quantum wells, exciton binding energy can be tuned on- and off-resonance with the longitudinal-optical phonon energy by varying the quantum well width. A comprehensive picture of this tunning effect on the temperature-dependent exciton absorption spectrum is derived, using the exciton Green's function formalism at finite temperature. The effective exciton-phonon interaction is included in the Bethe-Salpeter equation. Numerical results are illustrated for ZnSe-based quantum wells. At low temperatures, both a single exciton peak as well as a continuum resonance state are found in the optical absorption spectra. By contrast, at high enough temperatures, a splitting of the exciton line due to the real phonon absorption processes is predicted. Possible previous experimental observations of this splitting are discussed.Comment: 10 pages, 9 figures, to appear in Phys. Rev. B. Permanent address: [email protected]

Failure Correction of a Linear Array of Coupled Parallel Vertical Dipole Antennas, Journal of Telecommunications and Information Technology, 2020, nr 1

In this paper, a cuckoo search algorithm based on the combined characteristics of the brood parasite behavior and Levy flights is applied to correct the radiation pattern of a linear antenna array composed of parallel dipoles with faulty elements. An effort is made to restore the radiation pattern similar to one without any faulty elements, and the difference in the values of side lobe level and wide null depth of both patterns, as well as the voltage standing wave ratio obtained from the new voltage excitations become diminished. The examples presented in this paper show the effectiveness of this algorithm in correcting the radiation pattern of a linear array of 36 and 120 dipole antennas with four and ten failed elements, respectively. The results show that the matching condition and the wide null control produced by Cuckoo Search algorithm are more efficient in comparison with the benchmark failure correction algorithm. The approach adopted herein may be applied to other array configurations as wel

Design and Evaluation of HTTP Protocol Parsers for IPFIX Measurement

In this paper we analyze HTTP protocol parsers that provide a web traffic visibility to IP flow. Despite extensive work, flow meters generally fall short of performance goals due to extracting application layer data. Constructing effective protocol parser for in-depth analysis is a challenging and error-prone affair. We designed and evaluated several HTTP protocol parsers representing current state-of-the-art approaches used in today's flow meters. We show the packet rates achieved by respective parsers, including the throughput decrease (performance implications of application parser) which is of the utmost importance for high-speed deployments.Článek zkoumá syntaktické analyzátory HTTP protokolu, které rozšiřují síťové toky o informace z webového provozu. Výpočetně náročné získávání informací z aplikační vrstvy má vliv na výkon měřicích sond a může vést k výraznému poklesu jejich výkonu. Tvorba rychlého analyzátoru pro hloubkovou analýzu HTTP protokolu je náročný proces s ohledem na správné a včasné zpracování dat ze sítě. Článek porovnává naši implementaci vybraných metod pro analýzu HTTP provozu, které jsou v současnosti používány v sondách na měření síťových toků. Provedená měření ukazují množství paketů, které je sonda schopna zpracovat při zapnuté analýze HTTP a jak toto množství klesá oproti sondám, které analýzu aplikačních protokolů neprovádějí. Jedná se o významnou informaci pro nasazení měřicích sond ve vysokorychlostních sítích

Thermoelectric transport in Bi2Te3/Sb2Te3\text{Bi}_2\text{Te}_3/\text{Sb}_2\text{Te}_3 superlattices

The thermoelectric transport properties of $\text{Bi}_2\text{Te}_3/\text{Sb}_2\text{Te}_3$superlattices are analyzed on the basis of first-principles calculations and semi-classical Boltzmann theory. The anisotropy of the thermoelectric transport under electron and hole-doping was studied in detail for different superlattice periods at changing temperature and charge carrier concentrations. A clear preference for thermoelectric transport under hole-doping, as well as for the in-plane transport direction was found for all superlattice periods. At hole-doping the electrical transport anisotropies remain bulk-like for all investigated systems, while under electron-doping quantum confinement leads to strong suppression of the cross-plane thermoelectric transport at several superlattice periods. In addition, insights on the Lorenz function, the electronic contribution to the thermal conductivity and the resulting figure of merit are given