(2021). Editor’s message: cooling evolution for validating microwave heating models. Journal of Microwave Power and Electromagnetic Energy: Vol. 55, No. 3, pp. 173-174.

Abstract In this study, sour cherry nectar and apple juice were concentrated using thermal concentration (75, 80, and 85 °C), and intermittent microwave concentration (180, 300, and 450 W) under vacuum condition (at 250 mbar). Thirteen different mathematical models were used to describe the concentration kinetics of the samples. The Midilli model exhibited the best fit to all experimental data (R2

Abstract The common practice of applying reflection loss to material is incorrect as it can only be applied to film. Also the dominant theory of impedance matching should be replaced by wave cancellation theory. Here, we show that experimental data obtained from microwave absorption by the film of the titled composite can be successfully analyzed theoretically from our new theories. Formulae for the

Abstract In this study, the drying kinetics and quality characteristics of microwave-assisted hot air dried beef chips were investigated. For this purpose, beef slices were treated with spice mixture (4 g/100 g beef) and then dried with 2 different air temperature (60 and 70 °C) and 3 different microwave power (0, 90 and 180 W at fixed product weight). Drying process was terminated when moisture content

Abstract The main aim of the present investigation is to develop and synthesis the precious nano-metals such as nano gold and its by product components such as nano copper, nano silver etc. The investigations were basically consisting of two level environmental friendly process i.e., recovering of the gold from discarded E-waste components and secondly with the proper reaction after boiling. The precious

Abstract The work attempts to investigate the dielectric properties and microwave drying characteristics of Yunnan lignite, so as to upgrade it. The effect of drying temperature, moisture content and microwave heating frequency on dielectric properties was measured using resonant cavity method. Results indicate that both the values of ε′ and ε″ presented two stage at the investigated temperatures.

(2021). Editor’s message: Substance of non-communication applications in JMPEE. Journal of Microwave Power and Electromagnetic Energy: Vol. 55, No. 2, pp. 91-92.

Abstract To effectively separate and recover the valuable elements iron and boron from ludwigite, this study investigated the magnetic properties and the magnetic separation efficiency. And the reactivity of boron component in the B-bearing tailing was studied. The results indicated that the saturation magnetization of ore samples was increased with the increase of microwave power and heating time

Abstract We present a new approach to the study of microwave efficiency (MW) and microwave susceptors in the process of obtaining high quality nanopowders. Susceptors accelerate the processing of various poorly absorbent materials in the microwave field, reduce processing time and energy consumption. We calculated the electric field by a three-dimensional modelling of a microwave applicator designed

Abstract This article proposed a new solution to do the plasma cleaning under low pressure based on a domestic microwave oven. A conical bottle was placed in the oven according to the electric field distribution calculated by finite element method and Helmholtz equation. A vacuum pump was employed to make a low pressure environment in the bottle to generate plasma. Experiments demonstrated that discharges

Abstract This study discusses development of a microwave-heated thin-panel metamaterial absorber (MA) for application in aircraft deicing. The base of the MA was selected to be high-silica glass cloth reinforced polyimide (GCRP), manufactured through the autoclave process. The material’s surfaces were sprayed with metal powder as per the absorber design. In simulation with an optimized parameter set

Abstract Triode-based circuits are still the less expensive and more reliable high power sources for industrial applications between 13.56 and 40.68 Mhz. Among them, self-excited oscillators feature the lower cost but with a frequency stability preventing them to address all ISM frequencies and applications. This article demonstrates the possibility to model numerically self-excited oscillators with

(2021). Editor’s message: Microwave imaging advances. Journal of Microwave Power and Electromagnetic Energy: Vol. 55, No. 1, pp. 1-2.

Abstract To effectively separate the valuable minerals in ludwigite, this study investigated the grinding fineness behaviour and liberation characteristics. The results indicated that the particle yield of −75 μm with a microwave power of 4 kW for 40 s was increased by 18.22% in comparison to that of raw ore. The D(50) and D(90) raw-ore grinding products reached 53.52 and 215.16 μm, both of which were

Abstract Non-uniform heating has been a challenging problem in microwave heating due to ‘standing wave pattern’ and ‘thermal runaway’ problems. Cycled microwave heating was used to improve microwave heating uniformity of frozen products, while a relatively new approach of inverter heating was claimed to help preserve food quality during thawing/heating. In this study, finite-element-method-based coupled

Abstract The dielectric properties and electromagnetic wave absorbing performance of granular polysilicon have important influences on microwave smelting efficiency. In this study, the dielectric parameters (dielectric constant, dielectric loss factor and loss tangent) of granular polysilicon were measured from room temperature (25 °C) to 800 °C at 2450 MHz by using the cylindrical cavity perturbation

Abstract Developing a mathematical model for the dielectric properties of water over a wide range of frequencies helps design, develop, model and optimize processes involving the interaction of electromagnetic waves with water containing materials. Based on large data sets (1744 published dielectric measurements) from literature and significant extensions to mathematical models, which have also been

Abstract To effectively separate the valuable minerals in ludwigite, this study investigated the grinding fineness behaviour and liberation characteristics. The results indicated that the particle yield of −75 μm with a microwave power of 4 kW for 40 s was increased by 18.22% in comparison to that of raw ore. The D(50) and D(90) raw-ore grinding products reached 53.52 and 215.16 μm, both of which were

Abstract The dielectric properties and electromagnetic wave absorbing performance of granular polysilicon have important influences on microwave smelting efficiency. In this study, the dielectric parameters (dielectric constant, dielectric loss factor and loss tangent) of granular polysilicon were measured from room temperature (25 °C) to 800 °C at 2450 MHz by using the cylindrical cavity perturbation

Many simulations employed in microwave heating simplify the geometric model of the microwave cavity to reduce the complexity of the model. Some detailed design features of the cavity, such as magne...

Both microorganisms and viruses are germs; the difference is that the first ones are alive while the viruses are a sort of capsules with genetic material that reproduce themselves by replication in...

Abstract Three-stub waveguides are common impedance matching devices which are essential for a wide range of high-power microwave applications. Based on equivalent circuit analysis method, this article presents a novel matching algorithm which can be applied for three-stub tuners to implement continuous, automatic and real-time impedance matching. Equivalent model of a stub waveguide is firstly established

Abstract In the present work, microwave energy was used for casting Al 7039 alloy at 2.45 GHz in the ambient cavity environment. Effects of input power and insulation of the mould assembly during irradiation on charge melting and mould preheating were studied. Five different casts were produced at 1000 W, 1200 W, 1400 W, 1400 W with an insulated pouring basin and 1400 W with insulated mould assembly

Abstract Dielectric properties of a set of glasses having the composition (70-x)%V2O5 - x%ZnO − 10%SrO − 20%FeO is studied in terms of their permittivity and electric modulus. The dielectric data are collected at the frequencies 120, 103, 104 and 105 Hz and in the temperature range 300 − 523 K. The electric moduli are treated with different theoretical models. Good fitting to the experimental data

Abstract The complex relative permittivity study of samples of liberdux® syrup dissolved in distilled–deionized water is presented. It should be mentioned that excess of this syrup as pharmaceutical residual in water is considered an emerging contaminant. The study covers liberdux® concentrations from 0% v/v to 100% v/v, which were measured from 500 MHz to 20 GHz. For each sample, the parameters of

(2020). Editor’s message: a glance to virtual conferences. Journal of Microwave Power and Electromagnetic Energy: Vol. 54, No. 3, pp. 183-185.

Abstract This paper presents a stable, accurate and wideband microwave fractional order differentiator (MFOD) based on infinite impulse response filter. The fractional order differentiator (FOD) design problem is formulated in the z-domain. This formulation alliances with the transmission line elements in cascading. Real coded genetic algorithm (RCGA), particle swarm optimization (PSO) and cuckoo search

Abstract The effects of different drying methods (hot air drying (HAD), microwave drying (MD), and hot air-microwave combined drying (HAMCD) processes) on the drying characteristics, rehydration ability, colour, texture, moisture state, microstructure, and energy characteristics of tilapia fillets have been investigated. The best rehydration and recovery ratios of tilapia fillets were obtained using

Abstract In order to exploit the use of remote sensing, microwave heating/drying and water stress in the agricultural sector, it is necessary to determine the dielectric properties of plant materials (branches, leaves, roots, fruits). In this way, the yield and quality of agricultural products can be increased. In this study, dielectric parameters of the sweet cherry and sour cherry leaves are measured

Abstract In this paper, the electromagnetic shielding effectiveness results of the plain weave composite fabric and the analytical solution of metal mesh were investigated. The composite fabric made of cotton yarns twisted with 50 µm copper filaments was used in the experiment. As the fabric was weaved and stretched, it had square shaped apertures which had length of 1.2 mm. The electromagnetic shielding

Abstract Microwave-assisted hydrodistillation and conventional hydrodistillation (MAHD and HD) were used for a comparative study of extraction Callistemon citrinus Skeels leaf essential oils. The time required for a MAHD method is 75 minutes that for HD method is 3.5 hours, so MAHD requires lesser time. The increases in yield of extracted oil by MAHD (0.84%) is found compared oil extracted by HD (0

Ancient technology was aimed to manufacture tools and other devices using materials chosen due to their good structural properties. Toughness was an important criterion, but with invention of new artefacts led to greater requirements so that new materials were sought. The problem was that available materials in nature did not fulfil such needs, hence it was no longer a matter of materials choice, but

Abstract This work aims to improve the uniformity and efficiency of microwave heating. A dual-port simulation model based on the finite element method was built, and two pins were applied to the heating cavity. The impact of dual frequency and pins on the coefficient of variation (COV) and heating efficiency were investigated. The results demonstrated that the uniformity of dual-frequency heating can

Abstract Little published information exists examining the effect of heating methods on nutrient retention in single-serve frozen meals, which can have instructions for conventional and microwave ovens. In peer-reviewed references, there are no recent studies that address this question. This work compares the effect of two reheating methods on nutrient retention of a frozen single-serve meal that has

Abstract The thin layer drying of Eri silkworm pupae using microwaves combined with hot air was conducted. Several empirical models simulating thin layer drying of Eri silkworm pupae were selected and analyzed. Microwave power between 100 and 200 W and drying temperatures between 50 and 70°C were used in the study. The comparison between experimental results and those of the models indicated that the

Abstract The use of polyols as green solvents in conjunction with microwave heating (MH) has become a very attractive synthetic protocol nowadays. However, among the needs of this area, as well as any other that uses MH, figure the electromagnetic properties of the materials. In this context, the contribution of this work is provide dielectric data of three polyols: glycerol, 1,2-propanediol and 1

Abstract There are five stages in acid coagulation of milk and most studies miss out on a stage or two depending on the experiments performed. Dielectric studies of milk and various physico-chemical studies on the formation of yogurt are well studied and established. However, most of the papers deal with either a limited range of frequencies in the dielectric studies and hence are unable to reflect

(2020). Editor’s message: experiments with microwave kitchen ovens. Journal of Microwave Power and Electromagnetic Energy: Vol. 54, No. 1, pp. 1-2.

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

Abstract This study aimed to understand the microwave thermal regeneration mechanism of asphalt pavement and improve its regeneration quality. Asphalt mixtures containing moisture were regarded as a porous medium to study the multi-physical distribution law of asphalt mixtures in the microwave heating process. Mass and heat transfer models of moisture and a heat transfer model of asphalt mixtures were

Abstract The ionic strength (I) of a solution is a measure of the concentration of ions or a measure of the intensity of the electric field in a solution. In water treatment, the ionic strength allows the determination of total dissolved solids concentrations. In this work, different concentrations of MgSO4*7H2O in water are considered. This produces several levels of ionic strength. This varies from

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

Abstract Ce-substituted strontium hexagonal M-type SrCexFe12-xO19 ferrites (x = 0.0, 0.03, 0.05, 0.07, and 0.1) and various concentrations of poly(N-vinilpyrrolidone) (PVP) polymer were prepared by citrate sol-gel auto-combustion route, and their structural and magnetic properties were studied. The Fourier transform infrared spectroscopy (FT-IR) revealed bands at 437, 549, and 598 cm−1, related to

(2019). Editor’s message: Communication applications and perception of microwave effect. Journal of Microwave Power and Electromagnetic Energy: Vol. 53, No. 4, pp. 213-214.

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

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

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

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

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

(2019). Editor’s message: applied science and engineering for solving society needs. Journal of Microwave Power and Electromagnetic Energy: Vol. 53, No. 3, pp. 143-144.

Abstract Microwave heating in white corn (Zea mays L.) against Sitotroga cerealella was applied as a post-harvest treatment. Power levels of 293, 390 or 475 W were applied to batches of 250 g until reaching the target temperature of 50 °C in the grain centre and held for 3 min, followed by air-forced cooling during 3.5 min. One batch was left as a control without treatment. Thermocouples and thermal

Abstract The present study investigates the treatment of membrane concentrate leachate by thermal-activated persulfate catalysed with Ag(I). Activation of persulfate was done by microwave/conventional heating. The persulfate activation with microwave (MW) and conventional heating (CH) processes was compared with Taguchi multi-response optimization as robust design approach. Parameters affecting the

Abstract The investigation of injection locking of cooker magnetron by a solid-state microwave power source is reported. Experimental results show that a 2.45 GHz cooker magnetron can be locked in continuous wave operation. In the frequency-locking bandwidth, the magnetron output frequency can be tuned by adjusting the injection source. The maximum frequency-locking bandwidth of 12 MHz and noise of

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

Abstract To liberate magnetite from ludwigite, the dielectric properties of ludwigite are investigated by cavity perturbation method at 2.45 GHz from 20 to 800 °C. The results show dielectric properties of ludwigite with temperature can be divided into three stages: at the first stage (20–200 °C), the dielectric constant (ε′), dielectric loss factor (ε″) and loss tangent (tan δ) increase approximately

The International Years, proclaimed by the General Assembly of the United Nations, are intended to increase awareness of the general public about topics and events that became milestones in the development of the society, and to motivate the new generations to pursue in the actions to enrich science and culture. The International Year of Physics (2005), Astronomy (2009), Chemistry (2011), Crystallography

Abstract In many agricultural and industrial applications, moisture content needs to be determined in real time while the material is moving. For granular and particulate materials, density-independent calibration functions were used in microwave moisture sensors to minimize the effect of bulk density changes. Three of these calibration functions expressed in term of the attenuation, phase shift and

Abstract This study is concerned with the development of model-free adaptive control (MFAC) of microwave heating process for the industry application of microwave energy. Precise control of the material's time–temperature profile is essential for preventing thermal runaway. To achieve good tracking performance a data-driven MFAC with input constrain is proposed since it is hard to establish an accurate

Abstract Dielectric properties of canola seeds, corn, paddy rice, soybean and wheat were studied to determine the dependence of dielectric properties on frequency, moisture content and density of powdered seeds. In this context, several tests were done to find the relationship between the dielectric properties of the seeds at different frequencies (0.6–3 GHz) and at different moisture contents. Experimental

Abstract Apertures and slots of the enclosures come into prominence for heat allocation, ventilation, I/O cable, etc. These slots and apertures induce the coupling route of electromagnetic interference (EMI) from the inside to outside. So, electromagnetic shielding is usually used to decrease the emissions or to the progress of equipment immunity. In this paper, an effect of an aperture shape on the