45 research outputs found

    Development of a non-iterative macromodeling technique by data integration and least square method

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    In this paper, a new method is introduced to synthesize the original data obtained from simulation or measurement results in the form of a rational function. The integration of the available data is vital to the performance of the proposed method. The values of poles and residues of the rational model are determined by solving the system of linear equations using conventional Least Square Method (LSM). To ensure the stability condition of the provided model, a controller coefficient is considered. Also, using this parameter, the designer can increase the stability margin of a system with poor stability conditions. The introduced method has the potential to be used for a wide range of practical applications since there is no specific restriction on the use of this method. The only requirement that should be considered is Dirichlet condition for the original data, usually the case for physical systems. To verify the performances of the proposed method, several application test cases were investigated and the obtained results were compared with those gathered by the well-known vector fitting algorithm. Also, the examinations showed that the method is efficient in the presence of noisy data

    An Efficient Beam Steerable Antenna Array Concept for Airborne Applications

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    Deployment of a satellite borne, steerable antenna array with higher directivity and gain in Low Earth Orbit makes sense to reduce ground station complexity and cost, while still maintaining a reasonable link budget. The implementation comprises a digitally beam steerable phased array antenna integrated with a complete system, comprising the antenna, hosting platform, ground station, and aircraft based satellite emulator to facilitate convenient aircraft based testing of the antenna array and ground-space communication link. This paper describes the design, development and initial successful interim testing of the various subsystems. A two element prototype used in this increases the signal-to-noise ratio (SNR) by 3 dB which is corresponding to more than 10 times better bit error rate (BER)

    An Efficient Multi-Beam Array Architecture for L-Band Secondary Surveillance Radars

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    In this paper, the design and fabrication of a large array antenna with three required, Sum, Difference and Control beams for a monopulse Secondary Surveillance Radar (SSR) is presented. A special array element, which is a high gain dual dipole structure, is designed and tested. This element has 9.6 dB gain in 1060 MHz and does not need any balun. The main challenge of extracting three beams out of one beam feeding networks (BFN) has been resolved efficiently by maximum integration of all three in one network, reducing the number of required modules to one half. The complete 33-element array, working in 1030 MHz and 1090 MHz is designed based on the Taylor array factor. The complex feed network of this 6-meter long array has successfully been synthesized as modular as possible. Sum pattern was designed for 2.7o azimuth beam width and -20 dB side lobe level and Diff pattern with a deep null in the boresight of the Sum pattern. The Ctrl beam was also designed in order to cover the Sum beam except in the direction of the main lobe

    Optimization of lipase production by solid-state fermentation of olive pomace: from flask to laboratory-scale packed-bed bioreactor

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    Lipases are versatile catalysts with many applications and can be produced by solid-state fermentation (SSF) using agro-industrial wastes. The aim of this work was to maximize the production of Aspergillus ibericus lipase under SSF of olive pomace (OP) and wheat bran (WB), evaluating the effect on lipase production of C/N ratio, lipids, phenols, content of sugars of substrates and nitrogen source addition. Moreover, the implementation of the SSF process in a packed-bed bioreactor and the improvement of lipase extraction conditions were assessed. Low C/N ratios and high content of lipids led to maximum lipase production. Optimum SSF conditions were achieved with a C/N mass ratio of 25.2 and 10.2% (w/w) lipids in substrate, by the mixture of OP:WB (1:1) and supplemented with 1.33% (w/w) (NH4)2SO4. Studies in a packed-bed bioreactor showed that the lower aeration rates tested prevented substrate dehydration, improving lipase production. In this work, the important role of Triton X-100 on lipase extraction from the fermented solid substrate has been shown. A final lipase activity of 223 ± 5 U g1 (dry basis) was obtained after 7 days of fermentation.Felisbela Oliveira acknowledges the ïŹnancial support from Fundação para a CiĂȘncia e Tecnologia (FCT) of Portugal through grant SFRH/BD/87953/2012. JosĂ© Manuel Salgado was supported by grant CEB/N2020–INV/01/2016 from Project ‘‘BIOTECNORTE-Underpinning Biotechnology to foster the north of Portugal bioeconomy’’ (NORTE-01-0145-FEDER-000004). Luı ÂŽs Abrunhosa was supported by grant UMINHO/BPD/51/2015 from project UID/BIO/04469/2013 ïŹnanced by FCT/MEC (OE). This study was supported by the Portuguese Foundation for Science and Technology (FCT) under the scope of the strategic funding of UID/BIO/04469/2013 unit and COMPETE 2020 (POCI-01-0145-FEDER006684) and BioTecNorte operation (NORTE-01-0145-FEDER000004) funded by the European Regional Development Fund under the scope of Norte2020–Programa Operacional Regional do Norte. Noelia PĂ©rez-RodrĂ­guez acknowledges the ïŹnancial support of FPU fellowship from the Spanish Ministry of Education, Culture and Sports. The authors thank the Spanish Ministry of Economy and Competitiveness for the ïŹnancial support of this work (Project CTQ2015-71436-C2-1-R), which has partial ïŹnancial support from the FEDER funds of the European Union.info:eu-repo/semantics/publishedVersio

    Development of a new method for modeling a physical system in a rational expression

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    The presented paper shows a new method for modeling of a physical system in a rational expression. The method is based on a hybrid combination of the conventional least square method (LSM) and a robust recursive procedure. In the first step of the method, a sampling function is employed to establish a system of linear equations. Then, the QR decomposition method and a very fast iterative technique are simultaneously used to determine the unknown parameters. Also, it is shown that by regarding a scalar gain parameter, the stability of the final model can be controlled. To verify the performance of the presented method, several theoretical and practical examples are examined and the obtained results are compared with the simulation and measurement data

    IEEE Transactions on Antennas and Propagation: Vol. 6, No. 1, January 2014

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    1. An efficient method for antenna design optimization based on evolutionary computation and machine learning technique / B. Liu, et al. 2. Design method for circularly polarized fabry-perot cavity antennas / R. Orr, G. Goussetis, V. Fusco 3. Mirror-integrated dielectric resonator antenna / N. Yang, K.W. Leung, E.H. Lim 4. A Broad-band conductively-loaded slot antenna for pulse radiation / W. Kang, K. Kim, W. Kim 5. Hemispherical dielectric resonantor antenna based on apollonian gasket of circles-a fractal approach / B. Mukherjee, P. Patel, J. Mukherjee 6. Wind profiler radar antenna sidelobe reduction / B. Lindseth, et al. 7. A Band-reconfigurable antenna based on directed dipole / L. Ge, K.-M. Luk 8. Knowledge-based antenna pattern interpolation / M. Robinson 9. Frequency-reconfigurable antenna using metasurface / H.L. Zhu, et al. 10. Analysis and design of a 45 slant-polarized omnidirectional antenna / X.L. Quan, et al. 11. Modeling and Applications of a Chemical-Loaded UHF RFID Sensing Antenna With Tuning Capability / S. Manzari, G. Marrocco 12. UWB All-textile Antenna with Full Ground Plane for Off-Body WBAN Communications / P.B. Samal, P.J. Soh, G.A.E. Vandenbosch 13. Compact Dual-Band WLAN Diversity Antennas on USB Dongle Platform / W.-J. Liao, et al. 14. On the Analysis and Design of Reconfigurable Multimode MIMO Microstrip Antennas / C. Redondo, L. de Haro 15. Three Dimensional Dual-Polarized Frequency Selective Structure with Wide Out of-Band Rejection / B. Li, Z. Shen 16. Adjusment of Beamwidth and Side-Lobe Level of Large Phased-Arrays Using Particle Swarm Optimization / S.-H. Yang, J.-F. Kiang 17. Series-Fed MicrostripAntenna Lattice With Switched Polarization Utilizing Butler Matrix / I. Slomian K. Wincza, S. Gruszczynski 18. Energy Storage and Radiation Q of Infinite Planar Dipole Phased Arrays / D.-H. Kwon, D.M. Pozar Etc

    Beam shaping of X-band stepped choke ring antenna for LED satellite applications

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