Microwave-Circuit Optimization with Parallel Enhanced Fast Messy Genetic Algorithm (pefmGA)

Fast messy genetic optimization is found suitable for complex microwave circuit design. Increase in computation speed is achieved using several ordinary computers connected to a network. Calculations are running on background so that computers can be used for other purposes at the same time. Dynamic change of bounds, search space segmentation and gradient incorporation have significantly improved convergence rate. The new method has found global minimum in each run, while classic methods failed for some starting points

FDTD Stability: Critical Time Increment

A new approach suitable for determination of the maximal stable time increment for the Finite-Difference Time-Domain (FDTD) algorithm in common curvilinear coordinates, for general mesh shapes and certain types of boundaries is presented. The maximal time increment corresponds to a characteristic value of a Helmholz equation that is solved by a finite-difference (FD) method. If this method uses exactly the same discretization as the given FDTD method (same mesh, boundary conditions, order of precision etc.), the maximal stable time increment is obtained from the highest characteristic value. The FD system is solved by an iterative method, which uses only slightly altered original FDTD formulae. The Courant condition yields a stable time increment, but in certain cases the maximum increment is slightly greater [2]

Arbitrary Q-factor Dielectric Resonator

New circuit component, active resonator, is proposed for use in microwave and millimetrewave circuits. It consists of a common resonator and an amplifier, compensating for losses in the resonator. Properly designed, such an arrangement behaves as a (passive) resonator with dramatically increased quality factor. High quality factors can be achieved even at millimetrewave frequencies, where common resonators suffer from losses due to small skin depths. Viability of the component is experimentally verified at microwave region using a TE01 dielectric resonator and an oscillator

Seven State PTP for Vector Network Analyzer

A new, seven-state switched perturbation two-port (PTP) for vector reflection measurement based on scalar measurement only was designed and realized in microstrip structure using PIN diodes. The structure was experimentally tested by means of vector measurements of different impedances in frequency band with relative bandwidth of 2.5 octaves. Good agreement with data obtained using a precise vector network analyzer was achieved. The new calibration method for the PTP was designed and tested on real measured data

Aerogel-based metasurfaces for perfect acoustic energy absorption

[EN] The unusual viscoelastic properties of silica aerogel plates are efficiently used to design subwavelength perfect sound absorbers. We theoretically, numerically and experimentally report a perfect absorbing metamaterial panel made of periodically arranged resonant building blocks consisting of a slit loaded by a clamped aerogel plate backed by a closed cavity. The impedance matching condition is analyzed using the Argand diagram of the reflection coefficient, i.e., the trajectory of the reflection coefficient as a function of frequency in the complex plane. The lack or excess of losses in the system can be identified via this Argrand diagram in order to achieve the impedance matching condition. The universality of this tool can be further exploited to design more complex metasurfaces for perfect sound absorption, thus allowing the rapid design of novel and efficient absorbing metamaterials.This work was funded by the RFI Le Mans Acoustique, Region Pays de la Loire. This article is based upon work from COST Action DENORMS CA15125, supported by COST (European Cooperation in Science and Technology). N.J. acknowledges financial support from Generalitat Valenciana through Grant No. APOSTD/2017/042. J.-P.G and V.R.G. gratefully acknowledge the ANR-RGC METARoom (No. ANR-18-CE08-0021) project and the HYPERMETA project funded under the program Etoiles Montantes of the Region Pays de la Loire. J.S-D. acknowledges the support of the Ministerio de Economia y Competitividad of the Spanish government and the European Union FEDER through Project No. TEC2014-53088-C3-1-RFernandez-Marin, AA.; Jimenez, N.; Groby, J.; Sánchez-Dehesa Moreno-Cid, J.; Romero García, V. (2019). Aerogel-based metasurfaces for perfect acoustic energy absorption. Applied Physics Letters. 115(6):061901-1-061901-5. https://doi.org/10.1063/1.5109084S061901-1061901-51156Gesser, H. D., & Goswami, P. C. (1989). Aerogels and related porous materials. Chemical Reviews, 89(4), 765-788. doi:10.1021/cr00094a003Herrmann, G., Iden, R., Mielke, M., Teich, F., & Ziegler, B. (1995). On the way to commercial production of silica aerogel. Journal of Non-Crystalline Solids, 186, 380-387. doi:10.1016/0022-3093(95)90076-4Fricke, J., Lu, X., Wang, P., Büttner, D., & Heinemann, U. (1992). Optimization of monolithic silica aerogel insulants. International Journal of Heat and Mass Transfer, 35(9), 2305-2309. doi:10.1016/0017-9310(92)90073-2Gerlach, R., Kraus, O., Fricke, J., Eccardt, P.-C., Kroemer, N., & Magori, V. (1992). Modified SiO2 aerogels as acoustic impedance matching layers in ultrasonic devices. Journal of Non-Crystalline Solids, 145, 227-232. doi:10.1016/s0022-3093(05)80461-2Gibiat, V., Lefeuvre, O., Woignier, T., Pelous, J., & Phalippou, J. (1995). Acoustic properties and potential applications of silica aerogels. Journal of Non-Crystalline Solids, 186, 244-255. doi:10.1016/0022-3093(95)00049-6Ma, G., Yang, M., Xiao, S., Yang, Z., & Sheng, P. (2014). Acoustic metasurface with hybrid resonances. Nature Materials, 13(9), 873-878. doi:10.1038/nmat3994Yang, M., Meng, C., Fu, C., Li, Y., Yang, Z., & Sheng, P. (2015). Subwavelength total acoustic absorption with degenerate resonators. Applied Physics Letters, 107(10), 104104. doi:10.1063/1.4930944Romero-García, V., Theocharis, G., Richoux, O., Merkel, A., Tournat, V., & Pagneux, V. (2016). Perfect and broadband acoustic absorption by critically coupled sub-wavelength resonators. Scientific Reports, 6(1). doi:10.1038/srep19519Li, Y., & Assouar, B. M. (2016). Acoustic metasurface-based perfect absorber with deep subwavelength thickness. Applied Physics Letters, 108(6), 063502. doi:10.1063/1.4941338Jiménez, N., Huang, W., Romero-García, V., Pagneux, V., & Groby, J.-P. (2016). Ultra-thin metamaterial for perfect and quasi-omnidirectional sound absorption. Applied Physics Letters, 109(12), 121902. doi:10.1063/1.4962328Peng, X., Ji, J., & Jing, Y. (2018). Composite honeycomb metasurface panel for broadband sound absorption. The Journal of the Acoustical Society of America, 144(4), EL255-EL261. doi:10.1121/1.5055847Yang, M., Ma, G., Yang, Z., & Sheng, P. (2013). Coupled Membranes with Doubly Negative Mass Density and Bulk Modulus. Physical Review Letters, 110(13). doi:10.1103/physrevlett.110.134301Yang, Z., Mei, J., Yang, M., Chan, N. H., & Sheng, P. (2008). Membrane-Type Acoustic Metamaterial with Negative Dynamic Mass. Physical Review Letters, 101(20). doi:10.1103/physrevlett.101.204301Lee, S. H., Park, C. M., Seo, Y. M., Wang, Z. G., & Kim, C. K. (2010). Composite Acoustic Medium with Simultaneously Negative Density and Modulus. Physical Review Letters, 104(5). doi:10.1103/physrevlett.104.054301Zhang, J., Romero-García, V., Theocharis, G., Richoux, O., Achilleos, V., & Frantzeskakis, D. (2016). Second-Harmonic Generation in Membrane-Type Nonlinear Acoustic Metamaterials. Crystals, 6(8), 86. doi:10.3390/cryst6080086Zhang, J., Romero-García, V., Theocharis, G., Richoux, O., Achilleos, V., & Frantzeskakis, D. J. (2017). Bright and gap solitons in membrane-type acoustic metamaterials. Physical Review E, 96(2). doi:10.1103/physreve.96.022214Stinson, M. R. (1991). The propagation of plane sound waves in narrow and wide circular tubes, and generalization to uniform tubes of arbitrary cross‐sectional shape. The Journal of the Acoustical Society of America, 89(2), 550-558. doi:10.1121/1.400379Kergomard, J., & Garcia, A. (1987). Simple discontinuities in acoustic waveguides at low frequencies: Critical analysis and formulae. Journal of Sound and Vibration, 114(3), 465-479. doi:10.1016/s0022-460x(87)80017-2M. J. Powell , in Numerical Analysis ( Springer, 1978) pp. 144–157.Groby, J.-P., Huang, W., Lardeau, A., & Aurégan, Y. (2015). The use of slow waves to design simple sound absorbing materials. Journal of Applied Physics, 117(12), 124903. doi:10.1063/1.4915115Jiménez, N., Groby, J.-P., Pagneux, V., & Romero-García, V. (2017). Iridescent Perfect Absorption in Critically-Coupled Acoustic Metamaterials Using the Transfer Matrix Method. Applied Sciences, 7(6), 618. doi:10.3390/app706061

Electrostatically driven synthetic microjet arrays as a propulsion method for micro flight

A propulsion system based on acoustic streaming generated by Helmholtz resonators is presented. High frequency (>60 kHz) electrostatically driven micromachined Helmholtz resonators constitute the basic unit of the system. Microjets produced at the exit of these resonators can be combined to form a distributed propulsion system. A high yield (>85%) fabrication process is introduced for fabrication of individual as well as arrays of resonators. The fabrication results for ten different designs are presented. About 1000 resonators of similar design cover the surface of a 4-in. wafer, effectively converting it to a distributed propulsion system. A number of characterization methods such as monitoring the harmonics of the drive current, laser interferometry, hot-wire anemometry, acoustic spectrum measurement and video particle imaging are used to determine the structural and fluidic behavior of different resonator designs. Collapse and recovery times of the diaphragm in the electrostatic actuator of the resonator are characterized and reduced to less than 10 μs by optimizing the perforation design. The occurrence of acoustic streaming in the micron-scale is verified via video particle imaging. The jet streams produced with pulse drive at low frequencies (~1 kHz) are spatially profiled and jet velocities exceeding 1 m/s are measured at the exit of the resonators. It has been verified that the resonance frequencies of the device at 50 and 175 kHz can be closely predicted by modeling.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/47854/1/542_2005_Article_600.pd

Système membrane - couche d'air mince chez transducteurs électrostatiques et piézoplastiques

System membrane - air gap of an electrostatic and piezopolymer transducer. This paper describes analog models of electromechanical transducers with a diaphragm and the thin air film based on the electrostatic and piezoelectric (with piezopolymer membrane) principles