Microwave Technology Research Articles

Demonstration of a Josephson vortex-based memory cell with microwave energy-efficient readout

The ongoing progress of superconducting logic systems with Josephson junctions as base elements requires the development of compatible cryogenic memory. Long enough junctions subject to magnetic field host quantum phase 2π-singularities—Josephson vortices. Here, we report the realization of the superconducting memory cell whose state is encoded by the number of present Josephson vortices. By integrating the junction into a coplanar resonator and by applying a microwave excitation well below the critical current, we are able to control the state of the system in an energy-efficient and non-destructive manner. The memory effect arises due to the presence of the natural edge barrier for Josephson vortices. The performance of the device is evaluated, and the routes for creating scalable cryogenic memories directly compatible with superconducting microwave technologies are discussed.

Structural and cation distribution analysis of Nickel-Copper/Nickel-Magnesium Substituted Lithium Ferrites

Lithium ferrite (Li0.5Fe2.5O4) shows significant promise in electrical and electronic engineering. It possesses a crystal spinel crystal structure denoted as AB2O4, with "A" and "B" representing specific tetrahedral and octahedral lattice sites respectively. Analysis of X-ray diffraction (XRD) patterns aligns well with the JCPDS card (no. 38-0259), confirming the spinel structure with the Fd3m space group. However, an additional peak at 211 in the basic lithium ferrite suggests a subtle Fd3m to the P4132 phase change with a minor secondary hematite phase. Investigating the cation distribution in these ferrites is crucial for further exploration of their magnetic and dielectric properties. These ferrites find widespread applications in microwave technology and magnetic and electric energy storage devices.

Synthesis and Insecticidal Evaluation of 3,5-Dicyanopyridines Against Cotton Aphids via Microwave-Assisted Multicomponent Reactions.

Certain 2-amino-6-alkoxy-4-arylpyridine-3,5-dicyanide 1a-e were prepared via a straightforward process using microwave technology rather than conventional methods. This involved reaction of arylidenemalononitrile thru propanedinitrile in the occurrence of sodium alkoxide under MW. While, their positional isomer 4-amino-6-alkoxy-2-arylpyridine-3,5-dicyanide 3a-j have been separated from the reaction of aryl aldehydes with 2-aminoprop-1-ene-1,1,3-tricarbonitrile 2 in the presence of sodium alkoxide using microwave technic. Furthermore, the insecticidal properties of all synthesized compounds were observed with respect to Cotton aphid nymphs and adults. Neonicotinoid pesticides are indicated as the most effective pesticides toward aphids and many other pests. Many insecticides are discovered as novelties. As a result, several pyridine compounds were chemical method synthesized to serve as equivalents of neonicotinoids, a broad class of insecticides. With LC50 value of 0.03 mg/L, components 3g exhibit the highest insecticidal bioactivity. This work discusses how to find new chemicals that could be used as insecticidal agents in the future.

IEEE Microwave and Wireless Technology Letters Information for Authors

IEEE Microwave and Wireless Technology Letters Information for Authors

IEEE Microwave and Wireless Technology Letters publication

IEEE Microwave and Wireless Technology Letters publication

A novel microwave Doppler method for mass estimation of machine-picked seed cotton

Obtaining information on cotton yields and creating a spatial map of cotton production is the starting point for implementing precision agriculture. Microwave technology has been used for yield estimation in China for crops such as corn and soybeans and has shown strong applicability. However, research on cotton yield estimation using microwave technology is weak. Therefore, this paper proposes a method for seed cotton mass estimation based on the microwave Doppler method and designs bench tests to prove the feasibility of the method. First, a seed cotton speed estimation model was established based on the microwave Doppler effect and fast Fourier transform. On this basis, a seed cotton velocity estimation experiment was designed to study the effects of sensor installation angle and position, pipe collision friction, air resistance, and the interaction force between the seed cotton on the seed cotton movement velocity. The power spectral density (PSD) of the acquired microwave data is then estimated using the modified periodogram method. The least squares method was used to establish a linear regression model between seed cotton mass and the corresponding PSD, and finally the free-fall mass experiment and pneumatic conveying mass experiment yielded that the estimation errors of seed cotton mass were 7.30% and 6.17%, respectively. The experimental results show that the estimation error is small when using microwave technology for seed cotton mass estimation, which meets the requirements of actual operation.

Optimization bio-oil production from Chlorella sp. through microwave-assisted pyrolysis using response surface methodology

Optimization can streamline experimental trials by evaluating the parameters and parameter interactions used as the basis for a more optimal downstream process. This study aims to optimize the microwave-assisted pyrolysis process in producing bio-oil from microalgae using response surface methodology (RSM) complemented by an investigation of the reaction mechanisms. A number of key parameters (microwave power, absorbent-to-microalgae ratio, and pyrolysis time) were fine-tuned using a face-centered central composite design. The result showed that microwave technology in slow pyrolysis could produce the bio-oil from microalgae 12 times shorter than conventional heating and quadratic model with a high precision (R2 = 0.9832, R2adj = 0.9616) from RSM optimization in predicting experimental values yielded a peak bio-oil yield of 19.11% under specific conditions: 20 min of pyrolysis time, a 0.19 (w/w) microwave absorber to microalgae ratio, and 583 W power. As the complex biomass, the reaction mechanism in chlorella sp. towards this technology including decarboxylation, decarbonylation, dehydration, cracking, deoxygenation, and esterification was proved in GCMS analysis, revealing the presence of key functional groups such as aliphatic, aromatics, alcohols, nitrogenous compounds, fatty acid methyl esters (FAME) and Polycyclic Aromatics Hydrocarbons (PAHs).

Research on preparation of high activity and durable carbon-supported platinum catalyst for methanol electro-oxidation by a facile continuous microwave pipeline method

In methanol oxidation reaction (MOR), it is crucial for the catalyst that Pt particles uniformly cover the surface of the carrier and the Pt surface active sites can effectively remove the binding with CO. This article develops a simple and effective continuous microwave technology. Carbon loaded nano platinum was synthesized by rapidly and uniformly heating a ethylene glycol mixture containing carbon black (CB) H2PtCl6 using microwave radiation, with a Pt content of 49.5%. The experimental results indicate that platinum particles are uniformly loaded onto the carbon surface, with uniform shape and size, and an average particle size of 3.02 nm. And the Pt/C catalyst prepared by continuous microwave technology showed enhanced electrocatalytic activity (peak current density of 76.95 mA/cm2) in MOR after heating at appropriate temperature in N2 atmosphere, which exceeded the commercial catalyst TKK (47.07 mA/cm2) by 63.6%. And the catalyst's resistance to CO toxicity and durability; Higher than commercial Pt/C catalysts. Compared with traditional methods, continuous microwave technology exhibits higher energy utilization efficiency and faster reaction speed in the catalyst preparation process. This technology also has the ability to achieve continuous preparation, which is one of the effective technological approaches to achieve large-scale catalysts production.

Advanced Microwave Strategies Facilitate Structural Engineering for Efficient Electrocatalysis.

In the dynamic realm of energy conversion, the demand for efficient electrocatalysis has surged due to the urgent need to seamlessly integrate renewable energy. Traditional electrocatalyst preparation faces challenges like poor controllability, elevated costs, and stringent operational conditions. The introduction of microwave strategies represents a transformative shift, offering rapid response, high-temperature energy, and superior controllability. Notably, non-liquid-phase advanced microwave technology holds promise for introducing novel models and discoveries compared to traditional liquid-phase microwave methods. This review examines the nuanced applications of microwave technology in electrocatalyst structural engineering, emphasizing its pivotal role in the energy paradigm and addressing challenges in conventional methods. The ensuing discussion explores the profound impact of advanced microwave strategies on electrocatalyst structural engineering, highlighting discernible advantages in optimizing performance. Various applications of advanced microwave techniques in electrocatalysis are comprehensively discussed, providing a forward-looking perspective on their untapped potential to propel transformative strides in renewable energy research. It provides a forward-looking perspective, delving into the untapped potential of microwaves to propel transformative strides in renewable energy research.

Microwave Treatment of Minerals and Ores: Heating Behaviors, Applications, and Future Directions

The application of microwave technology in mineral metallurgy is a transformative approach to ore processing that offers new ideas about the current progressive depletion of resources and the environmental impact of mineral processing. This review delves into the principles, applications, and future directions of microwave treatment in mineral and ore processing. Microwave technology, characterized by its unique advantages such as rapid and uniform heating, selective heating, and energy efficiency, stands in contrast to traditional heating methods. It directly interacts with materials at the molecular level, enabling volumetric heating. The review encompasses a wide range of applications, including ore pre-treatment, drying, mineral processing, hydrometallurgy, smelting, and reduction. It highlights the role of microwave treatment in enhancing metal recovery, reducing energy consumption, and improving processing speeds. Future research directions are identified, focusing on enhanced equipment design, process optimization, integration with conventional methods, and technological innovations. The comprehensive overview assists researchers, engineers, and decision-makers in understanding the potential of microwave technology in mineral metallurgy, emphasizing its contribution to innovation and sustainability in the sector.

Analysis and research on the teaching reform of electromagnetic wave and microwave technology under the background of new business form

This paper studies the higher education in the national economic form change, college students learning state new form, education and industry, education information under the background, for profound theory, experimental equipment expensive, experimental conditions, in the student theory of weak, try to need the education teaching reform direction and reform measures. Among them, the education and teaching reform of microwave technology curriculum was piloted as an example. For the weak theoretical foundation of electromagnetic field and insufficient mathematical foundation, the course adopts the strategy of light theory requirement, heavy phenomenon cognition, and guiding the application of knowledge to practice. Through virtual simulation, the invisible electromagnetic field and electromagnetic wave make it easier for students to understand the knowledge context to form the knowledge system; Through online and offline mixed teaching, stress response teaching, promote students 'participation in classroom teaching, improve students' independent thinking ability and judgment and analysis ability, attract students' attention in classroom learning, and interest in the corresponding knowledge content. And then promote the students' self-study ability, research ability and design ability.

IEEE Microwave and Wireless Technology Letters publication

IEEE Microwave and Wireless Technology Letters publication

IEEE Microwave and Wireless Technology Letters Information for Authors

IEEE Microwave and Wireless Technology Letters Information for Authors

Accurate identification of cadmium pollution in peanut oil using microwave technology combined with SVM-RFE

A qualitative identification method of heavy metal cadmium concentration in peanut oil with microwave detection technology was presented. Initially, on the basis of national standards, the configured samples were classified into three categories: negative, which did not exceed the national standard; weak positive, which slightly exceeded the national standard; and strong positive, which far exceeded the national standard. Then, the obtained transmission index was subjected to data dimensionality reduction, using three feature dimensionality reduction methods, namely Principal component analysis (PCA) strategy, recursive feature elimination (RFE) algorithm, and RFE-PCA algorithm, respectively, and the dimensionality-reduced data were used as inputs to establish the random forest (RF) classification model, and the results showed that the three feature dimensionality reduction methods could achieve better prediction results. Among them, the RFE-PCA-RF model has the best prediction performance, at this time, the RFE algorithm retains 35 feature points and number of principal components (PCs) is 7. Next, the structure of RFE model is optimized, and the SVM-RFE-PCA-RF model is constructed by using support vector machines (SVM) as its weight allocator and the analysis of the results of its running 50 times reveals that the discriminative accuracy of the prediction set reaches 100% for 31 times, which meets the requirement of high-precision qualitative identification of three types of samples. Therefore, using microwave equipment for qualitative identification of cadmium content in peanut oil is feasible, and the SVM-RFE-PCA dimensionality reduction strategy proposed in this paper is also worth considering in the future.

Improved Simulated Annealing Algorithm on the Design of Satellite Orbits for Common-View Laser Time Transfer

Laser Time Transfer (LTT) has proven to be able to improve remote time transfer accuracy compared to microwave technology. The impact of satellite clock errors and atmospheric delays during LTT will be further reduced in the common-view mode. The challenge is presented as an optimization problem that is limited by satellite trajectories. This paper introduces an improved simulated annealing algorithm designed to maximize the common-view possibility among various station pairs within regional Satellite Laser Ranging (SLR) networks by optimizing satellite orbit trajectories. The study proposes a system model that integrates LTT principles with satellite visibility considerations. The simulated annealing algorithm is improved with new annealing strategies that incorporate control strategies, and modify the cooling function. Comparative simulation analyses demonstrate the effectiveness of the algorithm, resulting in a significant reduction in computation time by over 10 times. The optimized orbits exhibit common-view windows between 3.337 and 8.955 times longer than existing orbits. Further simulations are conducted to optimize the orbits, and common-view models are established for 45 pairs among 10 stations. The optimizations result in common-view times ranging from 6.183 to 60.633 min in the Asia-Pacific region and from 5.583 to 61.75 min in the Europe-to-Asia region. This can provide valuable references for designing satellite constellations.

Convective Drying of Apple Enhanced with Microwaves and Ultrasound—Process Kinetics, Energy Consumption, and Product Quality Approach

This research explores the drying kinetics of apples, evaluating the impact of convective drying (CV), ultrasonically assisted convective drying (CVUS), and convective–microwave processes (CVMW1 and CVMW2) on energy consumption, drying time, temperature profiles, and product quality. Ultrasound-assisted convective drying (CVUS) exhibited a 10% reduction in drying time and a distinct “heating effect”. Convective–microwave processes (CVMW1 and CVMW2) significantly reduced drying times (47% and 66%, respectively, compared to CV), raising concerns about potential deteriorative processes due to elevated temperatures. Numerical analysis, using the Midilli–Kucuk model, highlighted its robust fit and emphasized the influence of microwave and ultrasound on the effective diffusion coefficient. Quality assessment indicated enhancements in polyphenolic compounds, particularly in convective–microwave processes. The convective–microwave process at higher power (CVMW2) emerged as a balanced option, displaying improved kinetics, energy efficiency, and product quality. The findings underscore the potential of judiciously applying microwave and ultrasound technologies for significant energy reduction and process enhancement, with a recommendation for further exploration of new parameters. This study emphasizes the importance of considering both drying kinetics and product quality in evaluating drying processes for fruits and vegetables, providing valuable insights for industrial applications.

Preparation of Metal–Organic-Framework-Derived Fe-CN@CoCN Nanocomposites and Their Microwave Absorption Performance

Microwave technology is commonly used in many fields such as wireless communication and medical treatment, which are closely related to social development. However, electromagnetic pollution caused by microwaves is gradually increasing and the demand for high-performance microwave absorption materials is also increasing. Porous materials obtained by the pyrolysis of metal–organic frameworks (MOFs) at high temperatures exhibit good conductivity and magnetism, and the original skeleton structure of MOFs can be maintained; thus, MOF-derived materials can be considered viable candidates of microwave absorption materials. In this paper, Fe-CN@CoCN materials were prepared by pyrolyzing a ferrocene (Fc)-doped core–shell zeolite imidazole framework (Fc-ZIF-8@ZIF-67) at 700, 800, and 900 °C for 2 h in an Ar atmosphere. The obtained Fe-CN@CoCN-0.25-700 nanocomposite exhibited excellent microwave absorption (MA) performance with a minimum reflection loss (RLmin) of −42.27 dB at 5.68 GHz and an effective absorption bandwidth (EAB, RL < −10 dB) of 4.80 GHz at a thickness of 2.5 mm. The Fe-CN@CoCN-0.25-800 nanocomposite possessed optimized MA properties with an RLmin of −40.78 dB at 12.56 GHz and an EAB of 4.16 GHz at relatively low thickness of 2 mm. Fe-CN@CoCN nanocomposites are expected to be efficient materials for microwave absorption coatings.

Microwave Treatment of Three Different Types of Sewage Sludge Based on Their Solar Drying Exposure Time: Effect on Microorganisms, Water Content and Agronomic Aspects

This study aimed to treat sewage sludge through microwave irradiation at a laboratory scale. The objective was to investigate the effect of microwave irradiation on microorganisms, water content, organic matter, and agronomic nutrients present in sewage sludge. Three types of sewage sludges obtained from a full-scale wastewater treatment plant were considered: Sludge A (raw sludge), Sludge B (subjected to 15 days of solar exposure, achieving 48% dryness), and Sludge C (exposed to solar conditions and left open to the air for 23 months, reaching 94% dryness). These diverse sludges were exposed to microwave irradiation at various power levels (analysed variables: ε (Watts/g), θ (°C), T (min)). The specific exposure powers and temperature levels for the water reduction analysis were: 555, 955, 1355, and 1500 Watts/g and 55, 75, 95, and 105 °C, respectively. On the other hand, microbiological and agronomic nutrient analyses were conducted at 75 °C–1355 W and 95 °C–1355 W. After microwave exposure experiments, the results demonstrated the high effectiveness of microwave technology in eradicating indicator microorganisms of faecal contamination and reducing sludge volume while not affecting trace elements of significant agricultural value. The reduction in Escherichia Coli revealed that 4 min of irradiation was necessary to completely eliminate it to 0 ulog, indicating a 100% reduction, in Sludge A. In Sludges B and C, an additional 1 min was needed under conditions of 75 °C and 1355 W for a mass of 50 g. Moreover, Sludge A (46.27 × 105 or 4.80 ulog of dry matter), Sludge B (1.29 × 106 or 6.11 ulog of dry matter), and Sludge C (8.77 × 104 or 4.94 ulog of dry matter) were heavily contaminated with faecal coliforms. It took 6 min to reduce faecal coliforms to below the detection threshold.

Unraveling the impact of microwave-assisted techniques in the fabrication of yttrium-doped TiO2 photocatalyst

In this study, we investigate the role of microwave technology in the fabrication of yttrium-doped TiO2 through a comparative analysis of hydrothermal techniques. Microwave-assisted hydrothermal synthesis offers advantages, but a comprehensive comparison between microwave-assisted and conventional methods is lacking. Therefore, in our investigation, we systematically evaluate and compare the morphological, structural, and optical properties of yttrium-doped TiO2 samples synthesized using both techniques. The X-ray diffraction (XRD) patterns confirm the anatase tetragonal structure of the synthesized TiO2-Y systems, while the larger ion radius of yttrium (Y3+) compared to titanium (Ti4+) presents challenges for yttrium to incorporate into the TiO2 lattice. The X-ray Photoelectron Spectroscopy (XPS) revealed a significant difference in the atomic content of yttrium between the TiO2-Y systems synthesized using microwave-assisted and conventional methods. This finding suggests that the rapid microwave method is more effective in successfully doping TiO2 with rare earth metals such as yttrium. The photo-oxidation of carbamazepine (CBZ) using TiO2-Y systems demonstrated high efficiency under UV-LED light. Microwave-synthesized TiO2-Y demonstrates improved photo-oxidation efficiency of CBZ, attributed to enhanced absorption, charge transfer, surface area, and crystallite size. Overall, the microwave-synthesized TiO2-Y systems showed promising performance for the photo-oxidation of CBZ, with improved efficiency compared to conventional synthesis methods.

Mechanistic insights into microwave-accelerated permeation through graphene-based membranes

Two-dimensional (2D) membranes, composed of stacked 2D nanomaterials, are increasingly utilized in separation fields due to their structured interlayer channels and ease of modification. The application of microwave technology to 2D membrane separation enhances permeability, but the unclear strengthening mechanism limits the further applications of this technique. This study aims to elucidate the fundamental principle behind microwave-accelerated permeability by investigating the performance of two distinct 2D membranes in response to microwaves: a microwave-transparent graphene oxide (GO) membrane and a microwave-absorbing GO-based membrane doped with molybdenum disulfide (MoS2-GO). Experimental results demonstrate that compared to conventional heating, microwave irradiation amplifies water and ethanol permeation flux through the GO membrane by 122% and 154%, respectively, without observed changes in membrane structure via SEM, XRD, and Raman analyses. In addition, the microwave accelerated permeation also occurs (by 110%) when Rhodamine B - aqueous solution was used as feed liquid, while the rejection rate was remained at above 99%, indicating the promising applications of microwave technology in sewage treatment. Further experiments show that the microwave-induced augmentation of water/ethanol permeation through the GO membrane was primarily governed by the dielectric loss values of the feed liquid. In contrast, this dependence vanished in the MoS2-GO membrane, indicating that accelerated permeation was mainly determined by the interaction between microwaves and diffusing molecules in the 2D channels, disrupted by microwave absorbing MoS2 in the latter case. These findings offer comprehensive insights into the enhancement of membrane permeation induced by microwave irradiation.