Feed Point Research Articles

Three-dimensional numerical simulation of coal and papermaking trash co-combustion in a circulating fluidized bed

Circulating fluidized bed (CFB) combustion is a important method of waste treatment with the benefits of harmlessness, recycling, and energy recovery. Using the existing co-firing CFB boiler to dispose of waste can reduce investment in boilers and environmental protection equipment. However, there is currently limited research available on the co-combustion of coal and waste (especially for papermaking trash), and the mechanism of pollutant emissions during unit operation remains unclear. In this work, the co-combustion of coal and papermaking trash in a three-dimensional industrial-scale CFB are investigated by using the Dense Discrete Phase Model (DDPM) method. Both homogeneous reactions (such as fuel particle pyrolysis, combustion, and surface reaction) and non-homogeneous reactions (such as gas combustion and pollutant generation) are considered. The co-combustion characteristics are comprehensively analyzed in terms of gas distribution, chemical reaction rates, and bed temperature under various operating conditions, including fuel mixing ratio, secondary air arrangement, and excess air coefficient. The results are obtained by comparing the distribution profile along the height. By reducing the mixing ratio of papermaking trash, the excess air coefficient, and adjusting the secondary air arrangement in the lower region, an expanding, reducing atmosphere is observed in the vicinity of the fuel feeding point. This, in turn, leads to an increase in CO concentration and a decrease in NO emissions, which is attributable to the interplay of gas distribution, chemical reaction rates, and bed temperature. A reduction in NO gas emissions was achieved by adjusting the secondary air arrangement and the excess air coefficient. Overall, this work provides valuable insights into the co-combustion characteristics of coal and papermaking trash in an industrial-scale circulating fluidized bed boilers.

Effect of microbial growth types (suspended and attached) in anoxic zone of innovative one-stage anaerobic/anoxic/oxic bioreactor with airlift regime on nitrogen removal through combined mechanisms and phosphorous removal: A comparative study

The objective of this study was to treat different types of industrial wastewaters (milk processing wastewater, soft drink wastewater, and soybean oil plant wastewater) using modified configurations of a bioreactor called one-stage internal dual circulation airlift A2O (DCAL-A2O) bioreactor. The modification involved the use of physical barriers (baffle and packing media) to enhance the anoxic zone of the bioreactor. The study investigated the performance of bioreactors in simultaneously removing carbon, nitrogen, and phosphorus. The bioreactor was designed in three configurations: ordinary, baffled, and hybrid DCAL-A2O bioreactors, depending on the type of manipulation. Different operating conditions, such as hydraulic retention time (HRT), air flow rate (AFR), and anaerobic volume ratio (AVR), were examined simultaneously. The hybrid DCAL-A2O bioreactor was found to be highly suitable for wastewater treatment due to its superior biological performance, ease of operation, and cost-effectiveness when compared to two other bioreactors. The chosen bioreactor demonstrated high performance in terms of TCOD, TN, phosphorus removal efficiencies, and effluent turbidity. Specifically, it achieved removal efficiencies of 97.0% for TCOD, 92% for TN (with a concentration of 179.4 mg/L), 90% for phosphorus (with a concentration of 50.33 mg/L), and an effluent turbidity of 9 NTU. These results were obtained under optimal conditions, which included a HRT of 10 h, an AFR of 2 L/min, and an AVR of 0.464. The unique setup of the bioreactor demonstrated its undeniable ability to effectively treat wastewater from different feeding points. PCR tests confirmed the co-existence of multiple functional bacterial species, including AOB, NOB, denitrifying bacteria, anammox, PAOs, DPAOs, and GAOs. This provides strong evidence for concurrent removal of organics and nutrients in all three configurations of the integrated unit. In summary, this study emphasizes the need for ongoing research in energy efficiency to safeguard our environmental resources.

A Computer Vision Approach toward Verifying CFD Models of Stirred Tank Reactors.

Mixing is one of the most important nonchemical considerations in the design of scalable processes. While noninvasive imaging approaches to deliver a quantifiable understanding of mixing dynamics are well-known, the use of imaging to verify computational fluid dynamics (CFD) models remains in its infancy. Herein, we use colorimetric reactions and our kinetic imaging software, Kineticolor, to explore (i) the correlation of imaging kinetics with pH probe measurements, (ii) feed point sensitivity for Villermaux-Dushman-type competing parallel reactions, and (iii) the use of experimental imaging kinetic data to qualitatively assess CFD models. We report further evidence that the influences of the stirring rate, baffle presence, and feed position on mixing in a tank reactor can be informatively captured with a camcorder and help experimentally verify CFD models. Overall, this work advances scarce little precedent in demonstrating the use of computer vision to verify CFD models of fluid flow in tank reactors.

H-Shape Microstrip Patch Antenna: Design, Simulation, and Characterization

This paper presents the design, simulation, and characterization of an H-shape microstrip patch antenna intended for high-frequency applications. The proposed antenna is modeled using Computer Simulation Technology (CST) Microwave Studio, a powerful tool for simulating electromagnetic fields and optimizing antenna parameters. The H-shaped configuration is chosen to enhance the antenna's radiation characteristics, bandwidth, and gain, while minimizing size and surface wave effects. The design process involves parameter optimization, including substrate selection, patch dimensions, and feed point configuration, to achieve superior performance. Detailed simulation results are presented, demonstrating the antenna's return loss, VSWR, gain, and radiation pattern. The antenna operates efficiently with stable resonance, offering low return loss and high radiation efficiency. The simulation results confirm that the H-shape microstrip patch antenna is well-suited for various wireless communication systems, showing potential for integration in compact, high-performance devices. This paper serves as a step towards further optimization and practical implementation of H-shape microstrip antennas in advanced RF systems.

Design and Implementation of a Printed Circuit Model for a Wideband Circularly Polarized Bow-Tie Antenna

A crossed bow-tie antenna design for S- and C-Band (2.44–7.62 GHz) with a peak gain of 7.29 dBi is presented to achieve wideband radiation efficiency greater than 90% and circular polarization with a single feed point. The polarization of the antenna is modeled by the input admittance of crossed bow-ties, and the model predictions are validated by experiments. A wideband matching network is designed to be tightly integrated with the antenna and produce a 103% impedance bandwidth. The matching network is decomposed into an equivalent circuit model, and an analysis is presented to demonstrate the principles of the matching network design. A prototype of the optimized antenna design is fabricated and measured to validate the analysis.

Design and Modelling of a Modified High Gain Printed Vivaldi Antenna for EMC Measurements

This paper demonstrates the design, modeling, and analysis of a small size 180 × 165 × 1.6 mm3 printed broadband Vivaldi antenna for electromagnetic compatibility measurements. The proposed antenna is intended to be utilized as a reference antenna for emission and immunity tests inside the EMC Chamber through the band (0.8–5.5 GHz). Exponentially tapered slots were created based on mathematical equations to form an end-fire radiation antenna. Furthermore, microstrip and slot line stubs were employed to tune the impedance bandwidth. This antenna could be considered a 2-D Horn antenna with a size reduction of 64% and 67% since both antennas, Vivaldi and Horn are based on the same principle. Two rectangular slots were engraved near the feeding point to reshape and enhance the gain at lower frequency bands. Furthermore, the realized gain has been improved by approximately 3.5 dB and reached up to 10.7 dBi by introducing a pair of triangular reversal slots at the top edges of the structure. Moreover, this antenna has specifications that make it a suitable candidate to work as a reference antenna inside the EMC chamber compared to the classical Horn antenna offered for sale (PowerLOG® PRO 30800 and TBMA4).

Analytic Study for 66 kV Sub Transmission System Planning

The objective of this paper is to know the operationconditions of the system in terms of power flow, power losses and the weak points of the network. After which, solutionswere proposed for solving such problems. The strategic andmethodology for planning Criteria are chosen in a way thatmatches the general standards. A seventeen years plan isconsidered with short and long term planning applied andcomputed, system model was designed and a simulation forthis model was performed using NEPLAN software. A strategicplan for the 17 year next for 66 kV sub-transmission networkhas been obtained. The targeted network consists of four ringsfed from four 220KV feeding points and capable of providingan expected total demand of 253 MW.

DEVELOPMENT AND ASSESSMENT OF MANUAL AND AUTOMATED PID CONTROLLERS FOR THE OPTIMUM PRODUCTION OF ETHYLENE GLYCOL IN A CSTR

Industrially, one of the techniques used to enhance the optimum production of petrochemicals is the configuration of process control units such as gas chromatography (G.C. Analyzer) for concentration and thermocouple for temperature in the production system. This research focused on the application of the principles of mass and energy conservation in the development of dynamic or unsteady state models for predicting the behaviour of the system or process involved in the production of ethylene glycol from a reaction involving oxidation of ethylene-to-ethylene oxide which further undergoes hydrolysis to produce ethylene glycol in a continuous stirred tank reactor (CSTR). The high mathematical complexities of the mass and energy balance models of the Process as a result of the reaction kinetic scheme of the non-elementary reaction of the process which integrated both linear and non-linear terms into the models were resolved by the application of the principles of Taylor’s series expansion, Laplace Transform, partial fraction and matrix in the development of the dynamic models. Process simulation tool (Simulink) was utilized in the configuration of closed-loop systems with thermocouple and G. C. Analyzer, at the feed point of the reactor for process variables (temperature and concentration) control during the process using proportional, integral and derivative (PID) as controller parameters. The results of the process behaviour showed that manual tuning of different controller parameters experienced a high level of fluctuations and would not attain its stability or steady state even at a processing time above 16 seconds. Whereas, automatic tuning of desired controller gains of 1.361, 1.056 and 0.4109 for K P, K I and K D for temperature and pressure with a tuning time of 143.9 Seconds, requires a maximum time of 8 seconds for the system to attain stability. This study showed that automated tuning of the controller resulted in better performance characteristics for optimum production of ethylene glycol in a non-isotheral continuous stirred tank reactor within the shortest possible time.

Design, analysis and validation of a microstrip patch antenna with enhanced coupling for leaf moisture sensing: an IoT approach

An innovative IoT-based system utilizing a modified slotted microstrip patch antenna with enhanced coupling is presented for precise measurement of leaf moisture content. The antenna employs a rectangular slot above the feed point with an advanced coupling technique to enhance sensitivity. The antenna, fabricated on a 0.8 mm F4B substrate, is designed to resonate within the 2.40 to 3.0 GHz range under unloaded conditions. A parametric analysis focusing on leaf permittivity ranging from 20 to 30 is conducted to determine the antennas’ sensitivity. Experimental measurements of the reflection coefficient (S11) with respect to resonant frequency shift are performed with leaf samples as the samples under test (SUT). Experimental results reveal that the proposed patch antenna’s sensitivity is significantly enhanced, ranging from 0.57 to 1.67 times greater than that of traditional patch antennas for the five leaf samples tested. The antenna exhibits a sensitivity of 0.06 GHz and 0.02 GHz for the modified and enhanced coupling designs, respectively. The mean relative error between predicted and measured moisture content values is low at 0.038. The findings highlight the antenna’s increased sensitivity in detecting leaf moisture content and illustrate the potential of the proposed IoT-based system for real-time agricultural monitoring, marking an advancement in precision farming practices. The study validates the microstrip patch antenna’s capability as a moisture sensor through detailed sensitivity analysis, frequency shift measurements, and regression modeling.

Feeding intensity identification method for pond fish school using dual-label and MobileViT-SENet

Accurately identifying the fish feeding intensity is crucial for timely understanding the feeding demand, dynamically adjusting the feeding strategy, and reducing costs. For the variability and uncontrollability of the pond aquaculture environment, the densities of feeding fish schools aggregating to the feeding point exhibit significant variations. Consequently, different densities of fish schools present inconsistent characteristics in the image, even under the same feeding intensity, making the precise identification of feeding intensity difficult. To tackle this issue, a method for identifying the feeding intensity of pond fish schools based on dual-label and MobileViT-SENet (DL-MobileViT-SENet) was proposed. The fish school images were marked with labels indicating density and feeding intensity to establish the dual-label dataset. Subsequently, a proposed MobileViT-SENet network is trained using the dataset to obtain the dual-label pre-training weight incorporating both fish density and feeding intensity features. Two models are trained to identify density and feeding intensity based on the obtained weight. Finally, a dynamic feeding strategy for fish that integrates biomass, density, and feeding intensity is presented. The proposed method combines the density and feeding intensity labels to enhance the accuracy of identifying the feeding intensity of pond fish schools across various densities, and lays the groundwork for designing a dynamic feeding strategy. It was tested on authentic pond fish school images and yielded an accuracy of 97.95%. This value is superior to these comparison methods, demonstrating that this method can accurately identify the feeding intensity of pond fish and provide support for formulating a dynamic feeding strategy.

SIMULATION OF SOIL LOOSENING PROCESSES WITH COMPRESSED AIR

A model for describing soil loosening when exposed to compressed air is considered. The model allows you to calculate, depending on the compressed air pressure, the diameter of the hole and the depth of the feed point, the dilatancy zone (the area within which the created stresses will exceed the threshold and the loosening process will begin). The developed model is also used to describe soil loosening at several air supply points and at different jet directions.

Fractal Interpolation Function based Thin Wire Antennas

This paper presents an approach for the design of wire antennas based on fractal interpolation functions (FIFs). The interpolation points and the contraction factors of the FIFs are chosen as free parameters to modify the antenna geometry. The proposed structures’ gain and radiation pattern can be optimized using FIF parameters. Producible prefractal antennas obtained in the intermediate iterations of fractal generation have compact sizes compared to classical counterparts. The error in prefractal geometry and the original fractal is bounded, and can be determined in terms of the finest producible detail’s dimensions. The emerging structures have multiband behavior due to their self-similar and symmetric nature. To illustrate the approach, we have provided finite element based simulations for several prefractal antennas. |S11|, the gain, the radiation efficiency, the radiation patterns, and feed point impedances for the demonstrated antennas are calculated numerically. The results indicate that produced antennas can be used in applications that require limited mechanical size, multiple operating bands, and controlled radiation patterns.

Consensus-based secondary frequency control for parallel virtual synchronous generators

In off-grid operating modes, microgrids with Virtual Synchronous Generators (VSG) controlled inverters are limited to primary frequency control capabilities. When operating under the primary frequency control, if VSG's output frequency exceeds the safe operational range, it can adversely affect stable operation. Consequently, there is a need to implement a secondary frequency control strategy. This paper presents an analysis of the conventional secondary frequency regulation in VSGs. It reveals that when multiple VSGs in parallel to the Point of Common Coupling (PCC) with varied line impedances, the proportionate distribution of each VSG's active power output, post frequency control, does not align with predetermined ratios. In response to this challenge, the paper introduces a quasi-distributed secondary frequency control approach, tailored for systems with multiple feed-in points. This approach modifies the traditional method of compensating for frequency deviation through average ratio integral compensation, replacing it with a compensation based on a consensus algorithm. This negates the need for global communication and additional impedance measuring equipment. By facilitating information exchange between neighboring converters, it enables global control, effectively resolving the issue of line impedance parameters impacting the distribution of VSG's active power output. This decouples the previously strong correlation between line impedance and VSG's active power. The proposed method is characterized by its strong adaptability, scalability, and swift dynamic adjustments, significantly enhancing the fault tolerance of information exchange and the stability of microgrid operations. Finally, the correctness and effectiveness of the proposed improved control strategy are verified by simulation and HIL-based platform.

A Machine Learning Approach to Simulation of Mallard Movements

Machine learning (ML) is increasingly used in diverse fields, including animal behavior research. However, its application to ambiguous data requires careful consideration to avoid uncritical interpretations. This paper extends prior research on ringed mallards where sensors revealed their movements in southern Sweden, particularly in areas with small lakes. The primary focus is to distinguish the movement patterns of wild and farmed mallards. While well-known statistical methods can capture such differences, ML also provides opportunities to simulate behaviors outside of the core study span. Building on this, this study applies ML techniques to simulate these movements, using the previously collected data. It is crucial to note that unrefined application of ML can lead to incomplete or misleading outcomes. Challenges in the data include disparities in swimming and flying records, farmed mallards’ biased data due to feeding points, and extended intervals between data points. This research highlights these data challenges, while identifying discernible patterns, as well as proposing approaches to meet such challenges. The key contribution lies in separating incompatible data and, through different ML models, handle these separately to enhance the reliability of the simulation models. This approach ensures a more credible and nuanced understanding of mallard movements, demonstrating the importance of critical analysis in ML applications in wildlife studies.

Survival Estimation Using Multistate Cormack–Jolly–Seber Models—The Case of the Bearded Vulture Gypaetus barbatus in Spain

The bearded vulture (Gypaetus barbatus) is an endangered species with a specialist osteophagous (bone) diet. We estimated the survival and productivity of this vulture in the Aragonese Pyrenees, where the main population of the species in Europe is found. We used a database covering a period of 33 years (1987–2020). To estimate the probability of survival, we used Cormack–Jolly–Seber models with a Bayesian approach. Our models estimated a survival rate of 0.90 ± 0.08 in juveniles, 0.95 ± 0.04 in subadults and 0.92 ± 0.05 in adults. The survival probability increased over the study period in adults and subadults but not in juveniles. By contrast, productivity decreased over the same period. Our study provides updated information on the status of two demographic parameters of great importance to the species and allows us to identify the most vulnerable age classes and to plan conservation actions to improve the situation of the species in a territory that is a donor of specimens for reintroduction projects. The estimated survival values suggest that more caution should be exercised when planning these feeding points according to the use the species makes of them.

ITER ECH Transmission Line System Design and Status

The electron cyclotron (EC) heating & current drive (H&CD) system on ITER provides plasma heating by generating, transmitting, and launching high-intensity, high-frequency (170 GHz) electromagnetic wave energy steerable across the plasma cross-section. The transmission line (TL) subsystem connects the Matching Optics Unit (MOU) on each of the 24 gyrotrons to the 32 feed points in the four upper launchers and the 24 feed points in the equatorial launcher. Each TL must be able to operate at up to 1.2 MW of input power for up to 1 hour pulse lengths. The TL system contains 50 mm water-cooled corrugated waveguide, 90o miter bends, 140o miter bends, polarizer miter bend pairs, switches, expansion units, pumpouts, DC breaks, MOU-TL adapters, Radio Frequency (RF) loads, and isolation shutter valves. A detailed finite element analysis has been used to verify the thermo-mechanical performance of each component. The microwave performance has been analyzed using a 2-D electromagnetic code combined with a Monte Carlo code. This approach allows the impact of manufacturing and installation tolerances to be assessed and optimized to provide a high probability of achieving the system performance requirements. Prototypes of the waveguide and TL components have been fabricated and tested at high-power. Production contracts are now being issued for fabrication and delivery of the waveguide and components to ITER.

The improved stratified transformer for organ segmentation of Arabidopsis.

Segmenting plant organs is a crucial step in extracting plant phenotypes. Despite the advancements in point-based neural networks, the field of plant point cloud segmentation suffers from a lack of adequate datasets. In this study, we addressed this issue by generating Arabidopsis models using L-system and proposing the surface-weighted sampling method. This approach enables automated point sampling and annotation, resulting in fully annotated point clouds. To create the Arabidopsis dataset, we employed Voxel Centroid Sampling and Random Sampling as point cloud downsampling methods, effectively reducing the number of points. To enhance the efficiency of semantic segmentation in plant point clouds, we introduced the Plant Stratified Transformer. This network is an improved version of the Stratified Transformer, incorporating the Fast Downsample Layer. Our improved network underwent training and testing on our dataset, and we compared its performance with PointNet++, PAConv, and the original Stratified Transformer network. For semantic segmentation, our improved network achieved mean Precision, Recall, F1-score and IoU of 84.20, 83.03, 83.61 and 73.11%, respectively. It outperformed PointNet++ and PAConv and performed similarly to the original network. Regarding efficiency, the training time and inference time were 714.3 and 597.9 ms, respectively, which were reduced by 320.9 and 271.8 ms, respectively, compared to the original network. The improved network significantly accelerated the speed of feeding point clouds into the network while maintaining segmentation performance. We demonstrated the potential of virtual plants and deep learning methods in rapidly extracting plant phenotypes, contributing to the advancement of plant phenotype research.

Física eletromagnética da MPA: revisão abrangente das aplicações, projeto e análise de antenas de microfita para tecnologias 5G

This work presents a study focused on the electromagnetic evaluation of Microstrip Patch Antennas (MPAs) through electromagnetic simulation for 5G technology applications. The paper addresses two commonly used feeding structures – coaxial probe and transmission line. In our analysis, we observed the scattering and impedance matrices concerning feeding point variations. Additionally, a parametric study explored the impact of relative permittivity, length, width, and height on MPA electromagnetic performance for 5G frequency operation, understanding the physics of these antennas. The results revealed the following: varying the relative permittivity shifted the resonance frequencies and reduced gain; changing the patch length slightly shifted the resonance to lower frequencies without significant changes in the radiation pattern; adjusting the patch width maintained the resonance while increasing matching levels without significant radiation changes; and altering the substrate height shifted the resonance to lower frequencies.

Performance evaluation of a novel monofilar helical antenna with tapered cross-section wire fabricated via metal additive manufacturing

This paper presents a novel formulation for a generalized helical antenna that incorporates non-uniform helix diameters, non-uniform helix spacing, and non-uniform wire cross-section, providing additional degrees of freedom for optimization. By carefully defining the transition between the helix and the center feed point, a thicker wire was used at the base to enhance the antenna’s operating bandwidth capability and mechanical strength, eliminating the need for additional support structures. The fabrication process utilized metal additive manufacturing (MAM) with Maraging steel. The results demonstrate that the helical antenna with a tapered cross-section wire (with a thicker base and a thinner tip) exhibits significantly better performance compared to the control models for operation in the X-band. This design amalgamates impedance matching from antennas with uniform thick wires and radiation characteristics from antennas with uniform thin wires. The major contribution of this work is the demonstration that employing tapered wire cross-sections can enhance helical antenna performance, thereby introducing a new design parameter in metal additive manufacturing. Specifically, we present an eight-turn helical antenna that achieved a measured reflection coefficient less than −10 dB and axial ratio less than 1 dB over the X band, with a peak realized gain in RHCP of 10.8 dBic.

Experimental Study of Particle Transport and Deposition Distribution over Complex Terrains Based on Spherical Alumina

The transport and deposition of atmospheric particulate matter have attracted significant attention recently due to the increasing frequency of extreme disaster events, such as dust storms, volcanic eruptions, and extensive forest fires. The size distribution of the transported material and the conditions of the land–air interface are dominant factors in comprehending the detrimental potential of atmospheric particulate matter. However, it is still a challenge to understand the mechanism of dust deposition, especially over complex terrain. In an effort to investigate the deposition characteristics of particles over complex terrain, a series of experiments were conducted in a multifunctional environmental wind tunnel. The results show that the wind speed directly above the top of the mild slope model is significantly greater than that in the steep slope model, which indicates that a steep slope has a greater blocking effect on wind fields. At low wind speeds, the average wind speed at the top of the mild slope model is 17.8% higher than that at the top of the steep slope model, and at high wind speeds the average wind speed at the top of the mild slope model is 8.6% higher than that at the top of the steep slope model. The influence trend of the steep slope model and the combination model is basically the same, with both decreasing first and then increasing with the direction of wind velocity. The amount of surface deposition is greatly affected by the location of the feeding point and the microscale characteristics of the surface. In the steep slope model, the deposition is mainly distributed on the windward side, while the leeward side has a small amount of deposition. In the mild slope model, particles are deposited not only on the windward side, but also on the leeward side. The average rate of decline in deposition flux in the steep slope model is 88.4% and 75.1% in the mild slope model. The use of the combination model reduces the particle concentration at the back end compared with the single model. In three different models, the deposition on the windward side was shown to be significantly greater than that on the leeward side of the model. Our work increases understanding of the deposition of coarse dust particles over complex terrain and provides basic data for improving the accuracy of large-region particle transport and deposition simulations.