Journal of Microwave Power and Electromagnetic Energy最新文献

{"title":"Measurement and modelling of soil dielectric properties as a function of soil class and moisture content","authors":"H. Kabir, M. Khan, G. Brodie, D. Gupta, Alexis Pang, M. Jacob, E. Antunes","doi":"10.1080/08327823.2020.1714103","DOIUrl":"https://doi.org/10.1080/08327823.2020.1714103","url":null,"abstract":"Abstract In this study, four textural classes of soil (Clay, Clay Loam, Loam, and Loamy Sand) were used to investigate the dielectric properties of soils, using a vector network analyser with an open-ended coaxial probe kit at room temperature (25 ± 2°C) in the 700–7000 MHz microwave frequency range. Four levels of soil moisture content (oven dry, 33% field capacity, 66% field capacity and 100% field capacity) were maintained to perform the experiment with three replication and three observation each. The results showed that, with increasing soil moisture, from oven dry conditions to 100% field capacity, both the real (Dielectric Constant) and imaginary (Loss Factor) components of the dielectric properties increased; however, the responses were not linear. The dielectric properties of oven dry soils were very low compared with the soils with higher moisture content. Therefore, soil moisture was the major contributor to the dielectric behaviour of soil. The dielectric properties of sandy soil were much lower than the other soils; however, the dielectric loss factor of the Dookie clay soil was higher compare with the other soils. Models were developed to explain the dielectric properties of soils as a function of frequency and moisture content. The goodness of fit (r2) for these models varies between 0.952 for the Dookie Sandy Soil to 0.997 for the Dookie Loam Soil, suggesting that these models were adequate to describe the dielectric properties of these soils over the range of frequencies and moisture contents assessed in this study. Another model was developed to estimate the expected penetration depth of electromagnetic waves in these soils, based on the model of the dielectric properties. It was clear that penetration decreases with both frequency and moisture content. Low frequencies penetrate further into the soils than higher frequencies. Similarly, dry soils allow further penetration than moist soils.","PeriodicalId":16556,"journal":{"name":"Journal of Microwave Power and Electromagnetic Energy","volume":"35 1","pages":"18 - 3"},"PeriodicalIF":1.5,"publicationDate":"2020-01-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85010588","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Editor’s message: experiments with microwave kitchen ovens","authors":"Juan Antonio Aguilar Garib","doi":"10.1080/08327823.2020.1715584","DOIUrl":"https://doi.org/10.1080/08327823.2020.1715584","url":null,"abstract":"A noticeable number of manuscripts present results of experiments conducted with arrangements based on microwave kitchen ovens for different applications. The use of this kind of ovens is attractive due to its accessibility and low cost, and with several modifications performed by the researchers, such as altering the cavity or instrumentation, there is no doubt about their usefulness in many cases. Although their operation is simple, one problem is that their nominal power is not always accurate, which in regular household applications is not an issue. Still, there are reports of meals that do not reach the necessary temperature to ensure killing bacteria, even following directions on the packets, because the meal amount and processing time are set accordingly to a power value that could be lower than expected. Other microwavable items, such as heat pads, infant formulas, and depilatory wax, are heated in these ovens, and if the opposite occurs, then overheating is also possible. When these ovens are in laboratory experimental arrangements, it is necessary to consider that microwave power varies even under service, so that sometimes only short tests with long cooling times between them are appropriated so that a given power condition is reproducible. Even so, real magnetron power is unknown while often the nominal value is reported as the applied power, without considering losses or cavity geometry. It is quite acceptable to conduct this kind of simple test for comparison purposes or confirming if a material can be heated or not with microwaves. However, often that it should, details regarding power stability, reliability and the nature of the performed changes in the ovens are not reported in the manuscripts, therefore, drawing conclusions or validating parameters related to power from these experiments is questionable. This journal is aimed at non-communication applications of microwaves and RF, meaning that they are employed for purposes such as drying, extracting, and cooking, among others, intended towards industrial-scale or mass production. Indeed, the kitchen oven is a response to the demand for fast food and it is one of the most representative non-communication applications of microwaves. Foundations of microwave engineering for design of systems and devices for processing materials and substances are given by multidisciplinary sciences and arts, that include studies on interaction matter-wave, transport phenomena, materials science, as well as knowledge about the physical, chemical, and biological nature, if applies, of the substances. The development of applications always requires experimentation, and the microwave kitchen oven is quite available, hence there are excellent examples of its application for researching. Then, mention of its limitations is not against this use, yet it is not acceptable to overrule them and formulate conclusions about kinetics and efficiency issues without discussing the modifications, limitations, and t","PeriodicalId":16556,"journal":{"name":"Journal of Microwave Power and Electromagnetic Energy","volume":"5 1","pages":"1 - 2"},"PeriodicalIF":1.5,"publicationDate":"2020-01-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80798991","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Selection and modeling of simultaneous cooled microwave system for polycondensation of L-lactic acid","authors":"Başak Temur Ergan","doi":"10.1080/08327823.2020.1714107","DOIUrl":"https://doi.org/10.1080/08327823.2020.1714107","url":null,"abstract":"Abstract In this study, a simultaneous cooled-microwave (MW) system operating in isothermal conditions under constant and continuous MW irradiation was designed using outside cooling for glycerin. To design an appropriate simultaneous cooled-MW experimental system, many simultaneous cooling methods, cooling liquids and MW experimental systems have been tried. Among these MW systems, the coil-cooled-MW system was considered most suitable experimental system. On the other hand, o-xylene was selected as the cooling liquid with the cooling efficiency (1.56°Cmin−1) for the MW system. Then, a basic mathematical relation was derived by means of a dynamic thermal model of the system to estimate required MW power (P) and to ensure isothermal conditions. Consequently, the time-dependent glycerin temperature was shown with an average model error of 2%. For further testing the validity of the model in reactive mediums, MW-assisted polycondensation reaction of LA was performed at 120 °C by applying 245 W MW power calculated from the model equation. The experiment revealed that the temperature (TR) was kept constant at desired value with an error of 5.7%. In addition, that, polymerization rate, yield of products and energy saving in the MW system were higher than conventional heating (CH) counterparts.   Abbreviations: MW: microwave; CH: conventional heating; FO: flouroptic sensor; IR: infrared sensor; LA: L-Lactic acid; PLLA: poly-(L-lactic acid); b.p.: boiling point (°C); pTsOH: p-Toluenesulfonic acid; DMP: direct melt polycondensation; ROP: ring opening polymerization","PeriodicalId":16556,"journal":{"name":"Journal of Microwave Power and Electromagnetic Energy","volume":"14 1","pages":"63 - 80"},"PeriodicalIF":1.5,"publicationDate":"2020-01-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75434366","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Experimental investigation and design of sectoral waveguide TM01 to TE11 mode converter","authors":"Vikram Kumar, S. Dwivedi, P. Jain","doi":"10.1080/08327823.2019.1677428","DOIUrl":"https://doi.org/10.1080/08327823.2019.1677428","url":null,"abstract":"Abstract In this paper, an all-metal sectoral waveguide (SWG) mode converter has been proposed for TM01 to TE11 mode conversion, suitable for high-power application with high mode conversion efficiency and beam stability. Describing its operating principle, electromagnetic (EM) analysis has been carried out to observe the propagation behaviour in the different structure regions of the mode converter. A comprehensive design methodology, experimental investigation along with its beam stability performance has been presented. This design methodology has been typically demonstrated for 2.9–3.1 GHz frequency device; the performance of the designed device has been carried out using a commercial simulation code. To validate our design methodology and simulation, the results have been compared with experimental results and found in agreement. The proposed SWG mode converter has exhibited high conversion efficiency (98.4%) along with EM beam stability, suiting for the high-power applications.","PeriodicalId":16556,"journal":{"name":"Journal of Microwave Power and Electromagnetic Energy","volume":"365 1","pages":"276 - 295"},"PeriodicalIF":1.5,"publicationDate":"2019-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80327595","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Editor’s message: Communication applications and perception of microwave effect","authors":"Juan Antonio Aguilar Garib","doi":"10.1080/08327823.2019.1682364","DOIUrl":"https://doi.org/10.1080/08327823.2019.1682364","url":null,"abstract":"According to publications on microwave conferences and journals, the interest in the field of not communication applications covers a wide range of topics, such as agriculture, biomedical, chemistry, dielectric properties, drying, energy, food, industrial and scale-up, modelling, ovens design, plasma, and solid state, among many others. Non-thermal microwave effect is still a controversial issue, at least in terms of its justification, although there are many well supported reports of higher rate reactions with microwaves compared to conventional heating. Activation of different reaction mechanisms, and either volumetric or selective heating, more energy into the system, could provide an explanation to this observed effect. The two-step sintering process where temperature is increased above the sintering set point for a short time could be a sort of example of thermal issues involved. Therefore, it is essential for non-thermal studies to accurately know the temperature profile in the sample, which often is difficult, so that values are calculated, or estimated, though modelling. Despite this inconvenience, there are reports with results that seriously challenges thermal explanations, and that is why this field of microwave research is active. However, some words regarding microwave effect have been taken, mostly in the internet and social networking, for claiming that microwaves are cause of illness, alter nutritional meal values, and have other effects against healthy life, including infertility. Even earlier than these generalized claims, safety has been an issue, regardless their impossibility due to nature of microwave energy being not energetical enough to break chemical bonding, and thermal regulation of mammals, to produce such consequences. These topics have been studied as they have arisen, quite before the commercial internet and, of course, internet social networking, which penetration power made almost any subject interesting to a wide audience. Regarding experiments to proof the effect of microwaves, there are some, even presented in fair science projects that although well prepared, have a scientific rigor accordingly to the student’s level. For instance, there is an experiment where plants were watered with water that was previously heated with microwaves and then left to cool down, against running water watering, with the comparation of the appearance of only two plants, they made conclusions about microwave effect. For public interest, this becomes a matter of perception rather than science, social networks offer the chance to cast conclusions directly, without any proof, leading understanding to the general knowledge and common sense of the readers. Table 1 shows a roughly ranking of the number of pdf documents found in internet from a google search combining different words about the subject. The number changes each time that the search is conducted, but they are within the same range and ranking remains the same. Counting of d","PeriodicalId":16556,"journal":{"name":"Journal of Microwave Power and Electromagnetic Energy","volume":"34 4","pages":"213 - 214"},"PeriodicalIF":1.5,"publicationDate":"2019-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72625675","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A computation-driven, energy-efficient and hybrid of microwave and conventional drying process for fast gooseberry candy production","authors":"Chanpreet Singh, N. Saluja, Rajeev Sharma","doi":"10.1080/08327823.2019.1677431","DOIUrl":"https://doi.org/10.1080/08327823.2019.1677431","url":null,"abstract":"Abstract The health benefits of Indian gooseberry have resulted in a tremendous growth in its consumption in the form of tasty candy and marmalade prepared by drying process. The candy production process is limited by high drying time and plant size requirements as most of the processing production plants are equipped with conventional drying methods. Hence, the paper presents computational model defining relation between electric field pattern with heating and moisture diffusion in the product simultaneously. The boundary value applies on Maxwell’s equation solution as defined by gooseberry electrical properties. The solution to heat and mass transfer equation offers thermodynamic properties and profiles of gooseberry by microwave heating. The optimised process of moisture diffusion to the surface of gooseberry, followed by conventional heating, dries the sample uniformly and speeds up the process. The established relation offers a valid model for defining time for microwave and conventional heating of fresh gooseberry that takes it as an input and dries gooseberry candy as an output, thereby reducing the time of drying from 17 hours to 0.5 hour. The electromagnetic and thermodynamic results are obtained using simulation and are followed by experimental verification.","PeriodicalId":16556,"journal":{"name":"Journal of Microwave Power and Electromagnetic Energy","volume":"114 1","pages":"259 - 275"},"PeriodicalIF":1.5,"publicationDate":"2019-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79392569","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effects of power input and food aspect ratio on microwave thawing process of frozen food in commercial oven","authors":"W. Klinbun, P. Rattanadecho","doi":"10.1080/08327823.2019.1677430","DOIUrl":"https://doi.org/10.1080/08327823.2019.1677430","url":null,"abstract":"Abstract This research studied the effects of power level and aspect ratio by numerical and experimental analysis in the microwave heating process. The sample was congee frozen rice. A three-dimensional model developed to solve Maxwell’s equations and Fourier’s heat equations using the finite element method in COMSOL Multiphysics software. The simulated temperature results were validated experimental results to measure five locations temperature by fibre-optic sensors. The surface temperature was captured by an infrared camera. From the results, the RMSE values of transient temperature were between ranges of 6.14 and 12.88 °C. The calculated temperature contours were in a good agreement for the 300-s heating. In addition, the increasing heating rate was 27% at the higher power level (1300–1800 W). The aspect ratio of sample change was significant change uniformity occurred. Finally, the expected results from the study will provide a conceptual framework, critical parameters, and distribution of microwave oven applicable temperature for specific frozen food and its packing.","PeriodicalId":16556,"journal":{"name":"Journal of Microwave Power and Electromagnetic Energy","volume":"34 1","pages":"225 - 242"},"PeriodicalIF":1.5,"publicationDate":"2019-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88516109","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Dielectric properties of pulque at different temperatures from 0.1 to 25 GHz","authors":"T. Kataria, M. Sosa‐Morales, J. Olvera-Cervantes, R. Rojas‐Laguna, A. Corona‐Chavez","doi":"10.1080/08327823.2019.1677432","DOIUrl":"https://doi.org/10.1080/08327823.2019.1677432","url":null,"abstract":"Abstract For industrialized processes, microwave techniques for quality control and pasteurization methods may be required. For this reason the precise knowledge of the dielectric characteristics of foods are of prime importance. In this paper, we present the dielectric properties of pulque, a Mexican traditional drink. Three different pulque flavors (natural, strawberry and coconut/pineapple) are reported from 100 MHz to 25 GHz using an open-ended-coaxial probe and a vector network analyzer. This characterization was carried out for temperatures ranging from 20 to 70° C in steps of 10° C.","PeriodicalId":16556,"journal":{"name":"Journal of Microwave Power and Electromagnetic Energy","volume":"1 1","pages":"215 - 224"},"PeriodicalIF":1.5,"publicationDate":"2019-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82785134","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Optimisation of Microwave-Assisted Extraction of Squalene from Amaranthus spp. Seeds","authors":"M. A. Lozano-Grande, G. Dávila-Ortíz, J. García-Dávila, Gabriel Ríos-Cortés, E. Espitia-Rangel, A. Martínez-Ayala","doi":"10.1080/08327823.2019.1677429","DOIUrl":"https://doi.org/10.1080/08327823.2019.1677429","url":null,"abstract":"Abstract Squalene is a triterpene of pharmaceutical interest, due to its antioxidant and anticancer properties. Amaranth oil is a source of plant origin with high squalene content which is extracted by conventional methods that involve high cost, time-consuming and create large amounts of waste by-products or CO2 emissions. In this study, the microwave-assisted extraction (MAE) was used to obtain amaranth oil rich in squalene under closed conditions. The optimization of squalene yield (SQ) was conducted using response surface methodology by a Box-Behnken design (BBD) with 33 factors: time (20, 25, 30 min), solvent–co-solvent (50:50, 60:40, 70:30 v/v) and temperature (40, 60, 80 °C). The effect of factors on yield was measured by gas chromatography-mass spectrometry followed by a comparison of the yield and chemical composition than those obtained by Soxhlet extraction (n-hexane during 6 h). Optimal conditions produced a squalene yield of 16,456 mg·100g−1 oil versus 7,967 mg·100g−1 oil for conventional extraction. The ratio solvent and heating time significantly affected the yield, but the chemical composition and quality of extract were not affected, there were no oxidation products derived from the heat treatment. MAE has proven to be an environmental-friendly option with a significant reduction in time, energy and avoids solvent consumption.","PeriodicalId":16556,"journal":{"name":"Journal of Microwave Power and Electromagnetic Energy","volume":"50 1","pages":"243 - 258"},"PeriodicalIF":1.5,"publicationDate":"2019-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91378618","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The influence of nickel ions on the electric behaviour of P2O5–ZnO–Na2O glassy system","authors":"Y. Elbashar, S. S. Moslem, D. Rayan, H. H. Hassan","doi":"10.1080/08327823.2019.1643649","DOIUrl":"https://doi.org/10.1080/08327823.2019.1643649","url":null,"abstract":"Abstract P2O5–ZnO–Na2O glasses doped with various concentrations of NiO in the range from 0 to 6 mol % are prepared. The measurements of the electric properties of the samples are studied at different temperatures and frequencies. It is found that the dielectric constant decreases with increasing frequency as well as the electric modulus shows relaxation behaviour. The effect of different NiO concentrations and their chemical states in the glass network appears in the analysis of the activation energy, where Ni2+ ions have octahedral and tetrahedral states. From the frequency exponent result, the present samples exhibit correlated barrier hopping (CBH) conduction mechanism. The results show that some samples have great dielectric properties.","PeriodicalId":16556,"journal":{"name":"Journal of Microwave Power and Electromagnetic Energy","volume":"663 1","pages":"184 - 194"},"PeriodicalIF":1.5,"publicationDate":"2019-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86721370","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}