Dynamic measurement of dielectric properties of food snack pellets during microwave expansion

[EN] The in situ dielectric properties of a starch-based food pellet have been measured during microwave expansion. A dual-mode cylindrical cavity allowed simultaneous microwave heating and dielectric measurements of a single pellet inside a quartz tube, ensuring uniform heating during microwave processing. The cavity included additional measurement devices to correlate the dielectric properties with the main parameters of the expansion process, such as temperature, expansion time, pellet volume and absorbed power. A commercially available snack food pellet was Used as the test material for expansion experiments. Results indicated that dielectric constant (epsilon') and loss factor (epsilon") increased during heating, reaching a threshold value of epsilon' = 12.5 and epsilon" = 5.2, around a temperature of 115 degrees C when the material expanded and the dielectric properties dropped abruptly due to the loss of water content and the increase in size. This measurement procedure may provide useful material science information to improve the overall design of starch-based food pellets processed by microwaves. (C) 2017 Elsevier Ltd. All rights reserved.The work presented in this paper was funded by PepsiCo R&D.Gutiérrez Cano, JD.; Catalá Civera, JM.; Bows, J.; Penaranda-Foix, FL. (2017). Dynamic measurement of dielectric properties of food snack pellets during microwave expansion. Journal of Food Engineering. 202:1-8. https://doi.org/10.1016/j.jfoodeng.2017.01.021S1820

An Accurate and Compact High Power Monocycle Pulse Transmitter for Microwave Ultra-Wideband Radar Sensors with an enhanced SRD model: Applications for Distance Measurement for lossy Materiel

[EN] In This paper, a high power sub-nanosecond pulse transmitter for Ultra-wideband radar sensor is presented. The backbone of the generator is considered as a step recovery diode and unique pulse injected into the circuit, which gives rise to an ultra-wide band Gaussian pulse. The transistor driver and transmission line pulse forming the whole network are investigated in detail. The main purpose of this work is to transform a square waveform signal to a driving pulse with the timing and the amplitude parameters required by the SRD to form an output Gaussian pulse, and then into high monocycle pulses. In simulation aspect, an improved output response is required, in this way a new model of step recovery diode has been proposed as a sharpener circuit. This proposition was applied to increase the rise-time of the pulses. For a good range radar, a high amplitude pulse is indispensable, especially when it comes to penetrate thick lossy materiel. In order to overcome this challenge, a simple technique and useful solution is introduced to increase the output amplitude of the transmitter. This technique consists to connect the outputs of two identical pulse generators in parallel respecting the restrictions required. The pulse transmitter circuit is completely fabricated using micro-strip structure technology characteristics. Waveforms of the generated monocycle pulses over 10V in amplitude with 3.5 % in overshoot have been obtained. Good agreement has been achieved between measurement and simulation results.The author gratefully acknowledges the financial support provided by Pierre and Marie Curie University under the EMMAG Scholarship. This study was supported by DIMAS group, ITACA institute at City Polytechnic of innovation from university Polytechnic of Valencia.Ahajjam, Y.; Aghzout, O.; Catalá Civera, JM.; Penaranda-Foix, FL.; Driouach, A. (2019). An Accurate and Compact High Power Monocycle Pulse Transmitter for Microwave Ultra-Wideband Radar Sensors with an enhanced SRD model: Applications for Distance Measurement for lossy Materiel. Advanced Electromagnetics. 8(3):76-82. https://doi.org/10.7716/aem.v8i3.676S76828

Improvement of microstructural properties of 3Y-TZP materials by conventional and non-conventional sintering techniques

3 mol% Y2O3-stabilized zirconia nanopowders were fabricated using various sintering techniques; conventional sintering (CS) and non-conventional sintering such as microwave (MW) and pulsed electric current-assisted-sintering (PECS) at 1300 °C and 1400 °C. A considerable difference in the densification behaviour between conventional and non-conventional sintered specimens was observed. The MW materials attain a bulk density 99.4% theoretical density (t.d.) at 1300 °C, while the CS materials attain only 92.5% t.d. and PECS 98.7% t.d. Detailed microstructural evaluation indicated that a low temperature densification leading to finer grain sizes (135 nm) could be achieved by PECS followed by MW with an average sintered grain size of 188 nm and CS 225 nm. It is believed that the high heating rate and effective particle packing are responsible for the improvements in these properties. © 2011 Published by Elsevier Ltd and Techna Group S.r.l. All rights reserved.This work has been carried out with programme to support research and development of the Polytechnic University of Valencia (U.P.V) under multidisciplinary projects PAID-05-09 and PAID-05-10. A. Borrell, acknowledges the Spanish Ministry of Science and Innovation for her FPI Ph.D. grant and the people from Institute Technological of Materials (ITM) of the U.P.V for helping us with the microwave experiments during a stay in 2010-2011. Felipe L. Pefiaranda-Foix wants to thank the Generalitat Valenciana for the grant obtained in the frame of the Program BEST/2010, because some results of this paper have been possible with this help.Borrell Tomás, MA.; Salvador Moya, MD.; Rayón Encinas, E.; Penaranda-Foix, FL. (2012). Improvement of microstructural properties of 3Y-TZP materials by conventional and non-conventional sintering techniques. Ceramics International. 38(1):39-43. https://doi.org/10.1016/j.ceramint.2011.06.035S394338

Permittivity Spectrum of Low-Loss Liquid and Powder Geomaterials Using Multipoint Reentrant Cavities

[EN] Permittivity is a useful tool to characterize the composition and quality of many geomaterials. In general, the non-resonant permittivity measurement methods exhibit a higher degree of uncertainty than their resonant counterparts. In resonant measurements, the reduction in uncertainty comes typically with a loss in broadband. This article describes the theory, design, and application of multipoint coaxial reentrant resonant cavities applied to low-loss geomaterials at different temperatures. Specifically, a full-wave method based on circuit analysis is developed and applied for a circular corrugated waveguide. Moreover, the mode-matching method is applied to calculate the generalized admittance matrix (GAM). Two multipoint cavities and software were built and validated. The first cavity has five resonant frequencies, between 170 MHz and 2.3 GHz, and the second has four resonant frequencies, between 1.3 and 8.6 GHz. Thus, this method allows for ¿broadband-resonant¿ measurements. The permittivity values of liquid hydrocarbons, powdered kerogen, and pyrite are shown.Alvarez, JO.; Penaranda-Foix, FL.; Catalá Civera, JM.; Gutiérrez Cano, JD. (2020). Permittivity Spectrum of Low-Loss Liquid and Powder Geomaterials Using Multipoint Reentrant Cavities. IEEE Transactions on Geoscience and Remote Sensing. 58(5):3097-3112. https://doi.org/10.1109/TGRS.2019.2948052S3097311258

Directional Coupler Calibration for Accurate Online Incident Power Measurements

© 2021 IEEE. Personal use of this material is permitted. Permissíon from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertisíng or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.[EN] This letter proposes a calibration method to properly measure the incident power in a directional coupler (DC) when the measurement configuration has low directivity. The proposed method is based on measurements of short-circuits placed at different distances to calibrate the DC response. Results show that the method is clearly robust and provides accurate measurements even for directivities as low as 10 dB.This work was supported by the European Regional Development Fund (ERDF) through the Valencia Region 2014-2020 Operational Program under Project IDIFEDER/2018/027.Penaranda-Foix, FL.; Catalá Civera, JM.; Gutiérrez Cano, JD.; García-Baños, B. (2021). Directional Coupler Calibration for Accurate Online Incident Power Measurements. IEEE Microwave and Wireless Components Letters. 31(6):624-627. https://doi.org/10.1109/LMWC.2021.3070788S62462731

Detection of Anti-Counterfeiting Markers through Permittivity Maps Using a Micrometer Scale near Field Scanning Microwave Microscope

[EN] This paper describes the use of microwave technology to identify anti-counterfeiting markers on banknotes. The proposed method is based on a robust near-field scanning microwave microscope specially developed to measure permittivity maps of heterogeneous paper specimens at the micrometer scale. The equipment has a built-in vector network analyzer to measure the reflection response of a near-field coaxial probe, which makes it a standalone and portable device. A new approach employing the information of a displacement laser and the cavity perturbation technique was used to determine the relationship between the dielectric properties of the specimens and the resonance response of the probe, avoiding the use of distance-following techniques. The accuracy of the dielectric measurements was evaluated through a comparative study with other well-established cavity methods, revealing uncertainties lower than 5%, very similar to the accuracy reported by other more sophisticated setups. The device was employed to determine the dielectric map of a watermark on a 20 EUR banknote. In addition, the penetration capabilities of microwave energy allowed for the detection of the watermark when concealed behind dielectric or metallic layers. This work demonstrates the benefits of this microwave technique as a novel method for identifying anti-counterfeiting features, which opens new perspectives with which to develop optically opaque markers only traceable through this microwave technique.This paper has been financially supported through the grant reference BES-2016-077296 of the call Convocatoria de las ayudas para contratos predoctorales para la formacion de doctores de 2016 by Ministerio de Economia y Competitividad (MINECO) and by European Social Funds (ESF) of European Union, and the project SEDMICRON-TEC2015-70272-R (MINECO/FEDER) supported by Ministerio de Economia y Competitividad (MINECO) and by European Regional Development Funds (ERDF) of European Union.Gutiérrez Cano, JD.; Catalá Civera, JM.; Plaza González, PJ.; Penaranda-Foix, FL. (2021). Detection of Anti-Counterfeiting Markers through Permittivity Maps Using a Micrometer Scale near Field Scanning Microwave Microscope. Sensors. 21(16):1-14. https://doi.org/10.3390/s21165463S114211

Full-wave analysis of dielectric-loaded cylindrical waveguides and cavities using a new four-port ring network

“© 2012 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.”In this paper, a full-wave method for the electromagnetic analysis of dielectric-loaded cylindrical and coaxial waveguides and cavities is developed. For this purpose, a new four-port ring network is proposed, and the mode-matching method is applied to calculate the generalized admittance matrix of this new structure. A number of analyses on dielectric-loaded waveguide structures and cavities have been conducted in order to validate and to assess the accuracy of the new approach. The results have been compared with theoretical values, numerical modeling from the literature, and data from commercial electromagnetic simulators. The method has been also applied to the accurate determination of dielectric properties, and we provide an example of these measurements as another way to validate this new method. © 1963-2012 IEEE.This work was supported by the Ministry of Science and Innovation of Spain under Project MONIDIEL (TEC2008-04109). The work of F. L. Penarada-Foix was supported by the Conselleria de Educacion of the Generalitat Valenciana for economic support (BEST/2010/210).Penaranda-Foix, FL.; Janezic, MD.; Catalá Civera, JM.; Canós Marín, AJ. (2012). Full-wave analysis of dielectric-loaded cylindrical waveguides and cavities using a new four-port ring network. IEEE Transactions on Microwave Theory and Techniques. 60(9):2730-2740. https://doi.org/10.1109/TMTT.2012.2206048S2730274060

Microwave Sintering of zirconia materials: Mechanical and microstructural properties

Commercially, 3mol% Y2O3-stabilized tetragonal zirconia (7090nm) compacts were fabricated using a conventional and a nonconventional sintering technique; microwave heating in a resonant mono-mode cavity at 2.45GHz, at temperatures in the 11001400 degrees C range. A considerable difference in the densification behavior between conventional (CS) and microwave (MW) sintered materials was observed. The MW materials attain a full density of 99.9% of the theoretical density (t.d.) at 1400 degrees C/10min, whereas the CS reach only 98.0% t.d. at the same temperature and 1h of dwelling time. Therefore, the MW materials exhibit superior Vickers hardness values (16.0GPa) when compared with CS (13.4GPa).This work has been carried out under program to support research and development of the Polytechnic University of Valencia (U.P.V) under multidisciplinary projects, PAID-05-09 and PAID-05-10. A. Borrell acknowledges the Spanish Ministry of Science and Innovation for her FPI Ph.D. grant and the people from Institute Technological of Materials (ITM) of the U.P.V for helping us with the microwave experiments during a stay in 2010-2011. Felipe L. Penaranda-Foix thanks the Generalitat Valenciana for the grant in the frame of the Program BEST/2010 because some results of this paper have been possible with this help.Borrell Tomás, MA.; Salvador Moya, MD.; Penaranda-Foix, FL.; Catalá Civera, JM. (2012). Microwave Sintering of zirconia materials: Mechanical and microstructural properties. International Journal of Applied Ceramic Technology. 10(2):313-320. https://doi.org/10.1111/j.1744-7402.2011.02741.xS313320102Deville, S., Gremillard, L., Chevalier, J., & Fantozzi, G. (2005). A critical comparison of methods for the determination of the aging sensitivity in biomedical grade yttria-stabilized zirconia. Journal of Biomedical Materials Research Part B: Applied Biomaterials, 72B(2), 239-245. doi:10.1002/jbm.b.30123Binner, J., Annapoorani, K., Paul, A., Santacruz, I., & Vaidhyanathan, B. (2008). Dense nanostructured zirconia by two stage conventional/hybrid microwave sintering. Journal of the European Ceramic Society, 28(5), 973-977. doi:10.1016/j.jeurceramsoc.2007.09.002Anselmi-Tamburini, U., Garay, J. E., & Munir, Z. A. (2006). Fast low-temperature consolidation of bulk nanometric ceramic materials. Scripta Materialia, 54(5), 823-828. doi:10.1016/j.scriptamat.2005.11.015MENDELSON, M. I. (1969). Average Grain Size in Polycrystalline Ceramics. Journal of the American Ceramic Society, 52(8), 443-446. doi:10.1111/j.1151-2916.1969.tb11975.xChen, X. ., Khor, K. ., Chan, S. ., & Yu, L. . (2004). Overcoming the effect of contaminant in solid oxide fuel cell (SOFC) electrolyte: spark plasma sintering (SPS) of 0.5wt.% silica-doped yttria-stabilized zirconia (YSZ). Materials Science and Engineering: A, 374(1-2), 64-71. doi:10.1016/j.msea.2003.12.028Trunec, M., Maca, K., & Shen, Z. (2008). Warm pressing of zirconia nanoparticles by the spark plasma sintering technique. Scripta Materialia, 59(1), 23-26. doi:10.1016/j.scriptamat.2008.02.015Mazaheri, M., Hesabi, Z. R., Golestani-Fard, F., Mollazadeh, S., Jafari, S., & Sadrnezhaad, S. K. (2009). The Effect of Conformation Method and Sintering Technique on the Densification and Grain Growth of Nanocrystalline 8 mol% Yttria-Stabilized Zirconia. Journal of the American Ceramic Society, 92(5), 990-995. doi:10.1111/j.1551-2916.2009.02959.xGoldstein, A., Travitzky, N., Singurindy, A., & Kravchik, M. (1999). Direct microwave sintering of yttria-stabilized zirconia at 2·45GHz. Journal of the European Ceramic Society, 19(12), 2067-2072. doi:10.1016/s0955-2219(99)00020-5Upadhyaya, D. D., Ghosh, A., Gurumurthy, K. R., & Prasad, R. (2001). Microwave sintering of cubic zirconia. Ceramics International, 27(4), 415-418. doi:10.1016/s0272-8842(00)00096-1Mizuno, M., Obata, S., Takayama, S., Ito, S., Kato, N., Hirai, T., & Sato, M. (2004). Sintering of alumina by 2.45 GHz microwave heating. Journal of the European Ceramic Society, 24(2), 387-391. doi:10.1016/s0955-2219(03)00217-6Kuo, C.-T., Chen, C.-S., & Lin, I.-N. (2005). Microstructure and Nonlinear Properties of Microwave-Sintered ZnO-V2O5 Varistors: I, Effect of V2O5 Doping. Journal of the American Ceramic Society, 81(11), 2942-2948. doi:10.1111/j.1151-2916.1998.tb02717.xCong, L., Zheng, X., Hu, P., & Dan-feng Sun. (2007). Bi2O3Vaporization in Microwave-Sintered ZnO Varistors. Journal of the American Ceramic Society, 90(9), 2791-2794. doi:10.1111/j.1551-2916.2007.01848.xWang, J., Binner, J., Vaidhyanathan, B., Joomun, N., Kilner, J., Dimitrakis, G., & Cross, T. E. (2006). Evidence for the Microwave Effect During Hybrid Sintering. Journal of the American Ceramic Society, 89(6), 1977-1984. doi:10.1111/j.1551-2916.2006.00976.xMazaheri, M., Zahedi, A. M., & Hejazi, M. M. (2008). Processing of nanocrystalline 8mol% yttria-stabilized zirconia by conventional, microwave-assisted and two-step sintering. Materials Science and Engineering: A, 492(1-2), 261-267. doi:10.1016/j.msea.2008.03.023Ebadzadeh, T., & Valefi, M. (2008). Microwave-assisted sintering of zircon. Journal of Alloys and Compounds, 448(1-2), 246-249. doi:10.1016/j.jallcom.2007.02.032García-Gañán, C., Meléndez-Martínez, J. J., Gómez-García, D., & Domínguez-Rodríguez, A. (2006). Microwave sintering of nanocrystalline Ytzp (3 Mol%). Journal of Materials Science, 41(16), 5231-5234. doi:10.1007/s10853-006-0433-9Cheng, J., Agrawal, D., Zhang, Y., & Roy, R. (2002). Microwave sintering of transparent alumina. Materials Letters, 56(4), 587-592. doi:10.1016/s0167-577x(02)00557-8Nightingale, S. A., Dunne, D. P., & Worner, H. K. (1996). Sintering and grain growth of 3 mol% yttria zirconia in a microwave field. Journal of Materials Science, 31(19), 5039-5043. doi:10.1007/bf00355903Nightingale, S. A., Worner, H. K., & Dunne, D. P. (2005). Microstructural Development during the Microwave Sintering of Yttria-Zirconia Ceramics. Journal of the American Ceramic Society, 80(2), 394-400. doi:10.1111/j.1151-2916.1997.tb02843.xJanney, M. A., Calhoun, C. L., & Kimrey, H. D. (1992). Microwave Sintering of Solid Oxide Fuel Cell Materials: I, Zirconia-8 mol% Yttria. Journal of the American Ceramic Society, 75(2), 341-346. doi:10.1111/j.1151-2916.1992.tb08184.xANSTIS, G. R., CHANTIKUL, P., LAWN, B. R., & MARSHALL, D. B. (1981). A Critical Evaluation of Indentation Techniques for Measuring Fracture Toughness: I, Direct Crack Measurements. Journal of the American Ceramic Society, 64(9), 533-538. doi:10.1111/j.1151-2916.1981.tb10320.xNiihara, K., Morena, R., & Hasselman, D. P. H. (1982). Evaluation ofK Ic of brittle solids by the indentation method with low crack-to-indent ratios. Journal of Materials Science Letters, 1(1), 13-16. doi:10.1007/bf00724706Yucheng, W., & Zhengyi, F. (2002). Study of temperature field in spark plasma sintering. Materials Science and Engineering: B, 90(1-2), 34-37. doi:10.1016/s0921-5107(01)00780-2Acierno, D., Barba, A. A., & d’ Amore, M. (2003). Heat transfer phenomena during processing materials with microwave energy. Heat and Mass Transfer, 40(5), 413-420. doi:10.1007/s00231-003-0482-4Thostenson, E. T., & Chou, T.-W. (1999). Microwave processing: fundamentals and applications. Composites Part A: Applied Science and Manufacturing, 30(9), 1055-1071. doi:10.1016/s1359-835x(99)00020-2Matsui, K., Yoshida, H., & Ikuhara, Y. (2009). Isothermal Sintering Effects on Phase Separation and Grain Growth in Yttria-Stabilized Tetragonal Zirconia Polycrystal. Journal of the American Ceramic Society, 92(2), 467-475. doi:10.1111/j.1551-2916.2008.02861.xWilson, J., & Kunz, S. M. (1988). Microwave Sintering of Partially Stabilized Zirconia. Journal of the American Ceramic Society, 71(1), C-40-C-41. doi:10.1111/j.1151-2916.1988.tb05778.xUpadhyaya, D. D., Ghosh, A., Dey, G. K., Prasad, R., & Suri, A. K. (2001). Journal of Materials Science, 36(19), 4707-4710. doi:10.1023/a:1017966703650Winnubst, A. J. A., Keizer, K., & Burggraaf, A. J. (1983). Mechanical properties and fracture behaviour of ZrO2-Y2O3 ceramics. Journal of Materials Science, 18(7), 1958-1966. doi:10.1007/bf0055498

Bibliography, Background and Overview of UWB radar sensor

Due to the lack of studies in the literature that address the issue of UWB radar sensors, and also because of the great importance of this technology, which is gaining heavily in new application areas, such as the process industry and automotive engineering. A brief summary of the biography of UWB radar sensors have been treated and presented in this article, specifying the difference between pulsed radar sensors regarding CW radar sensor, and two subcategories SFCW FMCW, and highlight the benefits of each.Younes, A.; Catalá Civera, JM.; Penaranda-Foix, FL.; Driouech, A. (2014). Bibliography, Background and Overview of UWB radar sensor. International Journal of Engineering Research and Applications. 4(11):37-40. http://hdl.handle.net/10251/63314S374041