Current Control Method Research Articles

The use of silver nanoparticles against aflatoxin contamination in crops – mechanism, challenges and future scope

Abstract Certain Aspergillus spp. release harmful byproducts known as aflatoxins. These carcinogenic toxins contaminate crops, such as groundnut, maize, and rice. This contamination poses a significant health risk and economic burden. Current control methods have limitations. This review explores the potential of silver nanoparticles (AgNPs) as a novel strategy to mitigate aflatoxin contamination (AC). The review highlights the advantages of AgNPs, such as (1) antimicrobial properties against Aspergillus flavus and Aspergillus parasiticus, the aflatoxin producers; (2) effectiveness at concentrations that do not inhibit fungal growth, potentially reducing aflatoxin production; and (3) potential for eco-friendly synthesis using plant extracts. The review also discusses the potential drawbacks of AgNPs viz. (a) environmental concerns regarding accumulation and impact on beneficial soil microbes; and (b) cytotoxicity towards various organisms, requiring further research on safety. Studies suggest AgNPs can inhibit aflatoxin synthesis by disrupting the transcription of aflatoxin biosynthesis genes, damaging the fungal cell membrane and causing leakage of cellular components, and interfering with the secondary metabolism pathway. The review concludes that AgNPs offer a promising approach for aflatoxin control. However, further research is needed to address cytotoxicity concerns and optimise their safe and effective application in agricultural settings.

Predictive Current Control and Current Balance Method for Interleaved Buck EDM Pulse Generator

Predictive Current Control and Current Balance Method for Interleaved Buck EDM Pulse Generator

Grapefruit-derived nootkatone potentiates GABAergic signaling and acts as a dual-action mosquito repellent and insecticide.

Humanity has long battled mosquitoes and the diseases they transmit-a struggle intensified by climate change and globalization, which have expanded mosquito ranges and the spread of associated diseases.1 Additionally, widespread insecticide resistance has reduced the efficacy of current control methods, necessitating new solutions.2,3 Nootkatone, a natural compound found in grapefruit, shows promise as both a mosquito repellent and an insecticide.4,5 However, its mechanism of action remains unclear. Our study demonstrates that nootkatone acts as a potent spatial and contact repellent against multiple mosquito species. Nootkatone-induced spatial aversion, which is influenced by human odor, is in Aedes aegypti partially mediated by Orco- and ionotropic receptor (IR)-positive neurons, while contact aversion is robust and likely mediated via the proboscis and independent of TRPA1 and IRs. We further find that nootkatone potentiates γ-aminobutyric acid (GABA)-mediated signaling by modulating the broadly expressed major insect GABA-gated chloride channel resistant to dieldrin (Rdl). At low doses, the chemosensory-mediated spatial and contact repellency is likely strengthened by nootkatone's disruption of synaptic transmission in select mosquito sensory neurons. At higher doses, nootkatone induces paralysis and death, presumably through broad-range synaptic transmission disruption. These findings reveal nootkatone's unique mode of action and highlight its potential as an effective mosquito control agent. Its dual role as a repellent and an insecticide, combined with low-to-no toxicity to humans and a pleasant smell, underscores nootkatone's promise as a future tool in mosquito control efforts.

Effects of copper nanoparticles synthesized from the entomopathogen Metarhizium robertsii against the dengue vector Aedes albopictus (Skuse, 1894).

Aedes albopictus, known as the Asian tiger mosquito, is a significant vector for dengue fever, chikungunya, zika virus, yellow fever. Current control methods rely on chemical insecticides, which face challenges such as resistance, environmental harm, and impact on non-target species Eudrilus eugeniae and Artemia salina. This study evaluates the toxic effects of biogenic copper nanoparticles (CuNPs) synthesized using Metarhizium robertsii intracellular extract obtained from our previous research. The CuNPs were tested against A. albopictus and non-target species at 24 and 48 hours post-treatment. Results demonstrated that entomopathogenic fungi-derived CuNPs exhibited potent mosquitocidal activity, resulting in 97.33% mortality in larvae, 93.33% in pupae, and 74.66% in adults at 48 hours post-treatment. The CuNPs derived from M. robertsii showed lower LC50 values of 74.873 mg/L in larvae, 76.101 mg/L in pupae, and 136.645 mg/L in adults at 48 hours post-treatment. Additionally, 12 hours post-treatment, catalase (an antioxidant enzyme) activity decreased 1.5-fold in a dose-dependent manner, while glutathione S-transferase (a detoxification enzyme) activity increased 7.8-fold. CuNPs demonstrated lower toxicity to non-target species, with 24% mortality in A. salina and 24.44% mortality in E. eugeniae at 24 hours post-treatment. The LC50 values were 634.747 mg/L for A. salina and 602.494 mg/L for E. eugeniae at 24 hours post-treatment. These findings indicate that entomopathogenic fungi-derived CuNPs are a promising, target-specific candidate for controlling A. albopictus at various life stages (larvae, pupae, and adults).

Framework and case study for the assembly accuracy prediction of prefabricated buildings using BIM and TLS

ABSTRACT Tolerance management in the Architecture, Engineering, and Construction (AEC) sector faces challenges due to a lack of systematic scientific methods and tools. Quality issues in construction, coupled with inefficiencies, rework, and waste arising from deviation problems, hinder the sustainable development of the AEC sector. Current deviation control methods in the AEC field rely on compliance inspections and on-site rework, which are reactive and costly. In contrast, the manufacturing industry, closely linked to AEC, has developed highly automated methods for tolerance management. Although prefabricated buildings are manufactured off-site with high precision, the on-site assembly precision remains low, failing to fully leverage manufacturing industry capabilities. This research proposes a framework for predicting assembly accuracy of prefabricated buildings during the design and early construction stages. The framework, based on tolerance analysis methods from the manufacturing industry, integrates Building Information Modeling (BIM) and Terrestrial 3D Laser Scanning (TLS) technologies. This innovative approach offers a computer-aided method for conducting tolerance analysis in prefabricated buildings. A completed prefabricated building project serves as a case study, utilizing the framework to predict variations in critical dimensions, and the predictions align with measured results, demonstrating the feasibility of the proposed framework.

High-precision reconstruction of a heat flux boundary via a programmable scanning electron beam controlled by the voltage waveform design method

A scanning electron beam can be used to construct heat flux boundaries (HFBs). However, the long current response time in the deflection coil using a current control method (CCM) cause the deviation of the current waveform, potentially reducing the accuracy of the reconstructed HFB relative to the target HFB. The impact of the current response time on the reconstruction accuracy increases as the field frequency increases, and the accuracy can be reduced from 0.89 to 0.69. To shorten the current response time and improve the reconstruction accuracy, a voltage waveform design method (VWDM) is introduced as a replacement for the CCM. The result indicates that the accuracy of the HFB reconstructed by a scanning electron beam controlled by the VWDM can reach 0.91. Additionally, increasing the maximum output voltage of the power amplifier used to generate the voltage can further improve the reconstruction accuracy of the HFB with the VWDM. This study provides a new approach for the accurate construction of HFBs for rapid thermal processing, additive manufacturing and thermal assessment of hypersonic vehicles.

Analysis and control of the equilibrium position in bare electrodynamic tether systems

This study focuses on the calculation of the equilibrium position of the bare electrodynamic tether (BEDT) and the implementation of stable control during the de-orbiting process. A novel method for calculating the equilibrium position of the BEDT system is proposed, utilizing integral variable substitution. This approach provides an analytical expression for the equilibrium position, thereby addressing the limitations of numerical curve-fitting methods and facilitating further dynamic analysis and controller design. To address the influence of variations in geomagnetic field strength and electron density on the tether attitude during deorbiting, a sliding mode controller based on prescribed performance is designed to stabilize the BEDT around its equilibrium position by adjusting the tether length. This adjustment simultaneously regulates angular momentum and current on the tether. In contrast to conventional current switching methods, the proposed strategy effectively mitigates undesired transient responses and additional system disturbances, and accurately stabilizing the BEDT system around the equilibrium position. Numerical simulations show that the analytical equilibrium calculations closely match the nonlinear model, with an error margin of less than 5%. Additionally, the tether length adjustment strategy successfully stabilizes the system around the equilibrium position, achieving an angular deviation of less than 0.2 degrees and enhanced deorbit efficiency compared to the current switching control method.

Deadbeat predictive current control for high-speed permanent magnet synchronous motor based on extended state observer

Abstract Addressing the serious issue of delays in the high-speed controlling area and the impact of motor parameter mismatches on current loop performance, this paper proposes a high-speed PMSM current control method based on an extended state observer (ESO). To improve the angle delay, a leading phase angle is introduced for compensation. Additionally, a one-step-ahead predictive compensation for time delay is included in the control method to reduce the time delay. The ESO is also employed to estimate electrical parameters and compensate for control errors, enhancing the robustness. The simulation validates the effectiveness of the method.

A novel control strategy for PWM rectifier based on underactuated characteristics

In this paper, a double closed loop controller based on equivalent input disturbances (EID) error perturbation is proposed to solve the problem of abnormal operation of three-phase pulse width modulation (PWM) rectifier caused by load and external conditions. By analysing the buffeting problem and response time problem caused by traditional sliding mode in the current control process, a new current control method of terminal fuzzy sliding mode is designed. The system error is estimated by EID error estimation, and fuzzy control is introduced to improve the accuracy of error estimation, which solves the current buffeting and response problem. In order to solve the problem of response rate and harmonics in the voltage controller design, the extended state observer (ESO) in active disturbance rejection control (ADRC) control is improved, EID error estimation is introduced, the response rate and anti-disturbance ability of the system are further improved, and the harmonics of the system are suppressed. The experimental results show the effectiveness and superiority of the proposed method.

Wind effects on individual male and female Bactrocera jarvisi (Diptera: Tephritidae) tracked using harmonic radar.

Wind affects the movement of most volant insects. While the effects of wind on dispersal are relatively well understood at the population level, how wind influences the movement parameters of individual insects in the wild is less clear. Tephritid fruit flies, such as Bactrocera jarvisi, are major horticultural pests worldwide and while most tephritids are nondispersive when host plants are plentiful, records exist for potentially wind-assisted movements up to 200 km. In this study, harmonic radar (HR) was used to track the movements of both male and female lab-reared B. jarvisi in a papaya field. Overall flight directions were found to be correlated with wind direction, as were the subset of between-tree movements, while within-tree movements were not. Furthermore, the effect of wind direction on fly trajectories varied by step-distance but not strongly with wind speed. Mean path distance, step distance, flight direction, turning angle, and flight propensity did not vary by sex. Both male and female movements are well fit by 2-state hidden Markov models further supporting the observation that B. jarvisi move differently within (short steps with random direction) and between (longer more directional steps) trees. Data on flight directionality and step-distances determined in this study provide parameters for models that may help enhance current surveillance, control, and eradication methods, such as optimizing trap placements and pesticide applications, determining release sites for parasitoids, and setting quarantine boundaries after incursions.

A Force Control Method Integrating Human Skills for Complex Surface Finishing

Force control is one of the core modules for surface finishing such as grinding, polishing and sanding. However, the current force control methods based on human skills lack in-depth analysis of data patterns or are only applicable to flat surfaces. In addition, surface finishing is mainly performed by hand, resulting in low processing efficiency and poor product consistency. Therefore, this paper proposes a force control method that incorporates human skills to achieve relatively accurate force skill transfer and complex surface finishing. Firstly, human skills consisting of the force skill and the motion skill are learned. The force skill is used to generate the desired force. Then, a series of discrete poses are obtained based on human demonstration and combined with the motion skill to generate the desired trajectory. Finally, a computed-torque impedance control method is proposed to achieve relatively accurate force skill transfer and complex surface finishing by incorporating the desired trajectory and the desired force. The experiments are conducted on a platform composed of a 7-DOF collaborative robot manipulator from Franka Emika and a complex violin surface. The results demonstrate that the proposed force control method can achieve relatively accurate force skill transfer and improve the surface quality of the workpiece.

Model Predictive Current Control for Six-Phase PMSM with Steady-State Performance Improvement

The application of finite control set model predictive control (FCS-MPC) in six-phase permanent magnet synchronous motors (PMSMs) often faces a trade-off between computational burden and accurate voltage vector selection, as well as challenges related to harmonic components and torque generation. This paper introduces an improved model predictive current control (MPCC) method to address these problems. Firstly, 12 virtual voltage vectors are synthesized to improve torque output performance while suppressing harmonic currents. Then, to generate symmetrical switching signals and reduce switching loss, the largest basic vector used to synthesize the virtual vector is replaced by two medium vectors. Secondly, to solve the problem of the increased computational burden caused by the increase in discrete virtual vectors, a two-step vector selection method is proposed. In this method, each part is divided into several parts according to N, and the traditional cost function is also replaced by two-step functions. Different control performances can be achieved according to different values of N. Experimental results show that the proposed control scheme not only achieves stable current quality but also significantly improves steady-state performance throughout the entire speed range.

Research on an improved deadbeat model predictive current control of double three-phase open-winding permanent magnet motor

Model predictive current control has high control accuracy and good control performance, and has been widely applied in the control strategy of dual three-phase permanent magnet synchronous motors. This article proposes an improved deadbeat model predictive current control (DMPCC) method by analyzing the mathematical model of a dual three-phase open-winding permanent magnet synchronous motor. One inverter predicts and calculates the optimal voltage vector through the deadbeat model, while the other inverter calculates the optimal voltage vector through the value function rolling optimization. This method reduces the computational workload of the controller, avoids the delay problem of the traditional model predictive current control (MPCC) method, improves the system's response speed, effectively suppresses the current in the harmonic sub-plane, and reduces torque ripple. The simulation results have verified the accuracy and speed of the above control method.

Future semiochemical control of codling moth, Cydia pomonella

Codling moth (CM), Cydia pomonella, is a significant pest of apple (Malus domestica) and other orchard crops worldwide, posing challenges due to the decrease in registered insecticides, rising resistance, and a changing climate. The pest exhibits a strong resistance capacity to both synthetic and natural insecticides, while shifting seasonal temperatures disrupt the reliability of phenology-temperature models for predicting targeted control strategies. Alternative control strategies are necessary to future-proof control of this pest. Current control methods primarily rely on chemical insecticide sprays or granulosis virus applications during egg hatching. This review focuses explicitly on semiochemical-based manipulation of CM adults and larvae for control in orchards. Topics covered include the role of semiochemicals in integrated pest management, area-wide control, mating disruption, female attractants, larval kairomones, and incorporation into monitoring and control strategies. The potential of CM repellents in a push–pull strategy is also discussed. Primary sources for identifying relevant literature included GoogleScholar and ResearchGate, with a focus on papers published since 2013 but also include relevant papers from 2003. Nine review papers and 119 papers were reviewed. The review emphasizes that effective control necessitates an area-wide approach targeting all life stages (eggs, larvae, pupae, and adults). Comprehensive monitoring is crucial for identifying CM “hot-spots” and enhancing targeted interventions. Growers must consider landscape context when designing control programs. Lastly, recommendations are provided for future research and CM management strategies. There are opportunities to explore and exploit female kairomone attractants and repellents in control strategies and modify monitoring traps to be more attractive and autonomous.

Research on Decoupling Duty Cycle Optimization Control Method of a Multiport Converter for Dual-Port Direct Drive Wave Power Generation System

Dual-port direct drive wave energy power generation systems (DP-DDWEPGS) have received widespread attention due to their smooth and zero-free output power, compared to single-port direct drive wave energy power generation systems (SP-DDWEPGS) which have the disadvantage of large out-put power fluctuations. To further enhance the performance of the DP-DDWEPGS, optimal power capture control is proposed to achieve maximum power point tracking. Meanwhile, a multiport converter is applied to the DP-DDWEPGS to solve the problem caused by an excessive number of switching devices in the overall system converter. The multiport converter fulfills all the functional requirements of the DP-DDWEPGS while reducing the number of switching devices. However, switch multiplexing of the multiport converter also introduces coupling relationships between each port and the wave force exhibits time-varying characteristics, necessitating advanced control methods with superior fast-tracking capability. Therefore, in this paper, a decoupling duty cycle optimization model predictive control for DP-DDWEPGS is proposed. Based on the characteristics of switching multiplexing, NSC finite control set model predictive control (FCS-MPC) decouples the current prediction and the cost function, reduces the number of candidate voltage vectors in each operation, and shortens the operation time by 70%. To address the issues of high ripple value and increased error due to decoupling in FCS-MPC, duty cycle optimization control is added, greatly reducing the fluctuations in electromagnetic force and power of the permanent magnet linear generator (PMLG). Based on the established simulation model, the feasibility and superiority of the multiport converter and decoupling duty cycle optimization model predictive current control method are verified.

Model predictive current control method of dual three-phase permanent magnet synchronous motor based on improved SVPWM

Model predictive current control method of dual three-phase permanent magnet synchronous motor based on improved SVPWM

From biological potency absorbed components to artificial intelligence mining: A review of analytical strategies for the discovery and validation of quality marker in traditional Chinese medicine in the past decade

Quality control of Traditional Chinese Medicine (TCM) is fundamental to ensuring its clinical efficacy, with TCM formulas being the primary form used in clinical practice. Current quality control methods for TCM formulas often rely on pharmacopoeial standards for individual medicinal materials, typically encompassing only characteristic or partial active ingredients. These methods fail to fully reflect the clinical efficacy of TCM formulas. Consequently, exploring the multiple efficacious components in TCM formulas and establishing the correlation between multi-component content and efficacy has become an urgent issue in the modern quality assessment of TCM formulas. The quality marker (Q-marker) has emerged as a crucial standard in this field, achieving notable success in recent years. This paper reviews recent progress in the development of the Q-marker system in TCM by highlighting strategies based on the correlation between efficacy and constituents, using analytical techniques to investigate the material basis and efficacy of TCM. However, the aforementioned methods inevitably involve human selection factors. With the widespread application of artificial intelligence (AI) learning algorithms, it is now possible to develop a modern quality evaluation method for the multi-component “efficacy-quality” correlation in TCM formulas. This approach leverages AI techniques to explore novel and quantifiable methods for scientific and rational quality control in TCM formulas. In this paper, important future directions and questions in this field are also discussed.

Model-Free Current Predictive Control Method for Switched Reluctance Motors

Model-Free Current Predictive Control Method for Switched Reluctance Motors

Reconfigurable metasurface design via coplanar self-biasing structure

Reconfigurable metasurface enriches the functional integrated design into the originally limited space. Electrical control, through the external power supply to control the electromagnetic response control, is a common and simple control method. However, current methods of electrical control require external biasing circuits and even metallized through-holes to power the metasurface, thus leading the design and machining of the metasurface more complicated. In order to address this problem, we propose a coplanar self-biasing structure with feeder-structure multiplexing. Metasurface design is generated under connectivity control, and the electromagnetic responses under different voltage states are searched. The designed metasurface is fabricated and verified by measurement, which can prove that the metasurface can control one-dimensional far-field scattering beams. Moreover, the deicing function of the metasurface with integrated biasing line is verified by infrared measurement. All the measured results are consistent well with the expected targets, which shows the effectiveness of our ideas. Importantly, our design opens up a new way to simplify the reconfigurable metasurfaces design, which has a wide application value in the dynamic control of metasurfaces.

Improved Circulating Current Control Method to Reduce Energy Storage and Current Rating Requirements in MMC

Improved Circulating Current Control Method to Reduce Energy Storage and Current Rating Requirements in MMC