Direct Control Research Articles

Investigation of predictive direct torque control of Double Star permanent magnet synchronous machine (DSPMSM)

Investigation of predictive direct torque control of Double Star permanent magnet synchronous machine (DSPMSM)

Computational analysis of a four-flap valveless micropump (FFVM) for low reynolds number applications in microfluidic systems

Microfluidic systems are crucial in various fields including biological fluid handling and microelectronic cooling. Micropumps play a vital role in microfluidics. Valveless micropumps are the preferred choice in microfluidics because of their ability to minimize the risk of clogging and gently handle biological materials. In this comprehensive Four-Flap Valveless Micropump (FFVM) simulation, the fluid flow and associated deformation in the valveless micropump are analyzed. The oscillatory fluid motion generated by a straightforward reciprocating pumping mechanism is transformed into a unidirectional net flow by the micropump. This pump eliminates the need for intricate actuation mechanisms found in valve-based pumps while offering precise direction control. The input is given in terms of the Reynolds number or inflow velocity. In this study, the Reynolds numbers were changed from 16 to 50, which resulted in a positive correlation with the net flow rates, yielding a maximum net flow rate of 20.81 μl min−1 at a Reynolds number of 50. The influence of the average flow velocity is evident, with a peak net flow rate of 29.16 μl min−1 at 50 cm s−1. The FFVM showcases adaptability by delivering fluid within microfluidic pathways, holding promising applications in precision drug delivery systems.

Protective Effects of Lactoferrin Treatment Against Sodium Arsenite Exposure-Induced Nephrotoxicity.

It is said that a wide range of renal functions are at risk from arsenic exposure. We examined how lactoferrin administration may mitigate inflammation, apoptosis, redox imbalance, and fibrosis in order to counteract arsenic-induced nephrotoxicity. Accordingly, male C57BL/6 mice (6weeks) were divided into six experimental groups with six mice in each group. The first and second groups were intragastrically administered normal saline and sodium arsenite (NaAsO2) at 5mg/kg body weight concentrations as the negative control (NC) and NaAsO2 groups. The third, fourth, and fifth groups were intragastrically administered lactoferrin at concentrations of 100, 200, and 400mg/kg body weight in addition to NaAsO2 at concentrations of 5mg/kg body weight. The sixth group was intragastrically administered lactoferrin at a concentration of 200mg/kg body weight with the experimental group set as the lactoferrin group. After daily drug administration for 4weeks, the lactoferrin concentrations were optimized based on the results of renal index and renal function. Histopathological, biochemical, and gene expression analyses were performed to evaluate the status of renal tissue architecture, redox imbalance, inflammation, apoptosis, and fibrosis to confirm the alleviative effect of lactoferrin treatment against the NaAsO2 exposure-induced nephrotoxicity. The results confirmed that the 200mg/kg lactoferrin treatment mitigated these arsenic effects and maintained the normal renal frameworks. Conclusively, disrupting the renal redox balance and triggering inflammation, apoptosis, along with fibrosis is a milieu that arsenic, robustly exerts its nephrotoxic effect. Lactoferrin, probably by its direct and indirect control mechanism on these said pathways, can mitigate the nephrotoxicity and preserve the normal renal health.

Pain and subjective well-being among older adults in the developing world : A comprehensive assessment based on the WHO Study on Global Ageing and Adult Health

This paper studies the association of pain with subjective well-being (SWB) and time use among older adults in five low- and middle-income countries using data from the first wave of the WHO Study on Global Ageing and Adult Health. We suggest a novel use of anchoring vignettes as direct control functions to account for potentially correlated reporting behaviors such as correlated response scales when analyzing the relationship between subjective variables such as self-reported pain and SWB. Exploiting detailed data on individual time use and several complementary measures of SWB, including fine-grained activity-specific affective experiences derived from an abbreviated version of the Day Reconstruction Method, we find that both evaluative and experienced well-being are markedly lower for people living with pain compared to those without pain. These disparities persist even after controlling for possible confounding from reporting behaviors through the use of anchoring vignettes. Differences in experienced utility by pain status appear to be exclusively due to worse affective experiences during daily activities for those with pain, which seem to be partially mediated through changes in their functional limitations. Pain-related differences in time use, in turn, seem to provide only small compensating effects, underscoring important challenges to the use of changed activity patterns as a viable coping strategy for individuals enduring pain.

Fault tolerant control of permanent magnet synchronous motor based on hybrid control strategies DTC-SVM with second order sliding mode control using multi-variable filter

This paper describes direct torque control (DTC) of a permanent magnet synchronous machine (PMSM) powered by a two-level voltage inverter whose switching of switches is based on the Space Vector Modulation. To overcome the robustness of the control to the presence of a fault, we included an improvement of the direct torque control with Space vector modulation (DTC-SVM) by the use of the filters for the flux and the torque and compared to the direct torque control of the DTC-SVM, the PI controllers are replaced with sliding mode blocks, This control method allows giving a new structure DTC -SVM with sliding mode control. The analysis of the results shows good performances for the speed and a considerable reduction of the fluctuations at the level of the torque and the flux.

The wind turbine's direct power control of the doubly-fed induction generator

The study suggests a comprehensive approach to modeling and controlling variable-speed wind turbine systems that utilize doubly fed induction generators (DFIGs). To make sure that energy is transferred efficiently between the DFIG rotor and the grid, a two-level inverter with perfect bidirectional switches is used. Using the tip speed ratio algorithm and taking into consideration the randomness in wind speed, the maximum power at the wind turbine is optimized. Then, the control strategy utilizes direct power control (DPC) due to its various advantages. The advantages of employing this control technique are manifold. Firstly, it eliminates the necessity for rotor current control loops. Secondly, it obviates the need for controllers such as PI controllers to manage torque and flux. Furthermore, it has yielded exceptional simulation results when implementing direct power control (DPC) within the MATLAB/Simulink environment, specifically in the context of a doubly fed induction generator (DFIG) wind power system.

Can airports be a catalyst for reducing aviation’s effect on the climate?

The aviation ecosystem is increasingly coming under pressure to decarbonise from the public and governments. Airports are at the leading edge of transforming their operations, alongside airlines and aerospace companies. While, however, the levers to reduce Scope 1 and 2 airport emissions are well understood, how to address Scope 3 emissions (which account for the bulk of an airport’s emissions) remains a major challenge. This paper provides an overview of potential Scope 3 decarbonisation levers across aircraft operations, ground transport and infrastructure construction. The paper then assesses the potential impact on emissions, and ease of implementation of these levers, highlighting aircraft operations as the area with highest potential to reduce ecosystem emissions. Next, the paper looks at how some of these levers have been implemented in practice, based on the case study of Geneva Airport, focusing on supporting sustainable mobility, energy support for aircraft and financial incentives for airlines to use latest-generation aircraft. The paper then identifies and discusses key barriers that must be overcome, including the ability of airports to influence domains outside their direct control, competing governmental policies and need for investment, highlighting the need for collaboration between a wide range of stakeholders. Based on this, the paper suggests a number of actions that airports should take to satisfy stakeholders and catalyse the aviation ecosystem towards its goal of achieving net zero.

Torque Ripple Minimization of Six-Phase Switched Reluctance Motor Based on Enhanced Direct Instantaneous Torque Control

Torque Ripple Minimization of Six-Phase Switched Reluctance Motor Based on Enhanced Direct Instantaneous Torque Control

EMG-Constrained and Ultrasound-Informed Muscle-Tendon Parameter Estimation in Post-Stroke Hemiparesis.

Secondary morphological and mechanical property changes in the muscle-tendon unit at the ankle joint are often observed in post-stroke individuals. These changes may alter the force generation capacity and affect daily activities such as locomotion. This work aimed to estimate subject-specific muscle-tendon parameters in individuals after stroke by solving the muscle redundancy problem using direct collocation optimal control methods based on experimental electromyography (EMG) signals and measured muscle fiber length. Subject-specific muscle-tendon parameters of the gastrocnemius, soleus, and tibialis anterior were estimated in seven post-stroke individuals and seven healthy controls. We found that the maximum isometric force, tendon stiffness and optimal fiber length in the post-stroke group were considerably lower than in the control group. We also computed the root mean square error between estimated and experimental values of muscle excitation and fiber length. The musculoskeletal model with estimated subject-specific muscle tendon parameters (from the muscle redundancy solver), yielded better muscle excitation and fiber length estimations than did scaled generic parameters. Our findings also showed that the muscle redundancy solver can estimate muscle-tendon parameters that produce force behavior in better accordance with the experimentally-measured value. These muscle-tendon parameters in the post-stroke individuals were physiologically meaningful and may shed light on treatment and/or rehabilitation planning.

Closed-Loop Direct Power Control of Brushless DC Motor in Field Weakening Region

Closed-Loop Direct Power Control of Brushless DC Motor in Field Weakening Region

A Novel Switching-Table-Based Direct Torque Control With Improved Current and Torque Steady-State Performance for Dual Three-Phase PMSM

A Novel Switching-Table-Based Direct Torque Control With Improved Current and Torque Steady-State Performance for Dual Three-Phase PMSM

Enhancing of single-stage grid-connected photovoltaic system using fuzzy logic controller

The power generated by photovoltaic (PV) systems is influenced by environmental factors. This variability hampers the control and utilization of solar cells' peak output. In this study, a single-stage grid-connected PV system is designed to enhance power quality. Our approach employs fuzzy logic in the direct power control (DPC) of a three-phase voltage source inverter (VSI), enabling seamless integration of the PV connected to the grid. Additionally, a fuzzy logic-based maximum power point tracking (MPPT) controller is adopted, which outperforms traditional methods like incremental conductance (INC) in enhancing solar cell efficiency and minimizing the response time. Moreover, the inverter's real-time active and reactive power is directly managed to achieve a unity power factor (UPF). The system's performance is assessed through MATLAB/Simulink implementation, showing marked improvement over conventional methods, particularly in steady-state and varying weather conditions. For solar irradiances of 500 and 1,000 W/m<sup>2</sup>, the results show that the proposed method reduces the total harmonic distortion (THD) of the injected current to the grid by approximately 46% and 38% compared to conventional methods, respectively. Furthermore, we compare the simulation results with IEEE standards to evaluate the system's grid compatibility.

Functional traits of predators and decomposer prey determine context dependency in trophic control over ecosystems.

Research Highlight: Piccoli, G. C. d. O., Antiqueira, P. A. P., Srivastava, D. S., & Romero, G. Q. (2024). Trophic cascades within and across ecosystems: The role of anti-predatory defences, predator type and detritus quality. Journal of Animal Ecology, 00, 1-14. https://doi.org/10.1111/1365-2656.14063. Ecosystem functioning is controlled by the interplay between bottom-up supply of limiting nutrients and top-down animal feedback effects. However, the degree of animal versus nutrient control is context-dependent. A key challenge lies in characterizing this context dependency which is hypothesized to depend on differences in animal functional traits. Reporting on an important experiment, Piccoli etal. (2014) evaluate how interactions among functionally different predators and decomposer prey create context dependency in top-down control of a model system-tropical bromeliad tank ecosystems. Bromeliad plants hold water in their tanks supporting microcosm ecosystems containing terrestrial and aquatic insect larvae and arachnids. The ecosystems are supported by nutrients in plant litter that rains down from forest canopies into the tanks. Nutrients are released after litter is decomposed by a functionally diverse community of larval insect decomposers that differ in feeding mode and antipredator defence strategy. This decomposer community is preyed upon by an exclusively narrowly ranging aquatic insect larval predator and widely ranging spider predator that crosses between the aquatic and surrounding terrestrial ecosystems. Experimental manipulation of the animal community to test for the degree of control by predators mediated by the functionally diverse prey community included four treatments: (i) a control with the detritivores composing different function groups but without predators, (ii) the cross-ecosystem spider predator added, (iii) the purely aquatic damselfly larvae predator added and (iv) both predator types added to capture their interacting effect on ecosystem function (decomposition, nutrient release, and plant growth). Notably, the study resolved the causal pathways and strengths of direct and indirect control using structural equation modelling. These findings reveal how context dependency arises due to different capacities of the predators alone and together to overcome prey defences and control their abundances, with attendant cascading effects that diminished as well as enhanced decomposition and nutrient release to support bromeliad plant production. The study reveals that predators have a decided, albeit qualitatively and quantitatively different, hand in shaping the degree of bottom-up control through feedback effect on the release of limiting nutrients. This ground-breaking study provides a way forward in understanding the mechanisms determining context dependency in the control over ecosystem functioning.

A Direct Optimal Input Determination Data-Based Predictive Current Control for PMSM Drives Without System Identification

A Direct Optimal Input Determination Data-Based Predictive Current Control for PMSM Drives Without System Identification

Research on cooperative control of vehicle path tracking and lateral stability

Abstract This study presents a novel trajectory tracking control approach integrating steering angle and wheel torque output. Unlike conventional hierarchical methods, it considers front wheel steering angle and direct swing torque control simultaneously. Utilizing Model Predictive Control for autonomous vehicles, the system employs path tracking deviation as the state variable, front wheel steering angle, and overall additional yaw moment as control inputs. The coordinated control strategy enhances vehicle stability and contributes to heading angle changes, improving trajectory tracking accuracy. Simulation results in Matlab/Simulink demonstrate the validity and superiority of the proposed method in trajectory tracking and vehicle stability.

Joint Beam Direction Control and Radio Resource Allocation in Dynamic Multi-Beam LEO Satellite Networks

Joint Beam Direction Control and Radio Resource Allocation in Dynamic Multi-Beam LEO Satellite Networks

Spatial evolution of the proton-coupled Mott transition in correlated oxides for neuromorphic computing.

The proton-electron coupling effect induces rich spectrums of electronic states in correlated oxides, opening tempting opportunities for exploring novel devices with multifunctions. Here, via modest Pt-aided hydrogen spillover at room temperature, amounts of protons are introduced into SmNiO3-based devices. In situ structural characterizations together with first-principles calculation reveal that the local Mott transition is reversibly driven by migration and redistribution of the predoped protons. The accompanying giant resistance change results in excellent memristive behaviors under ultralow electric fields. Hierarchical tree-like memory states, an instinct displayed in bio-synapses, are further realized in the devices by spatially varying the proton concentration with electric pulses, showing great promise in artificial neural networks for solving intricate problems. Our research demonstrates the direct and effective control of proton evolution using extremely low electric field, offering an alternative pathway for modifying the functionalities of correlated oxides and constructing low-power consumption intelligent devices and neural network circuits.

Direct Yaw Moment Control for Distributed Drive Electric Vehicles Based on Hierarchical Optimization Control Framework

Direct Yaw Moment Control for Distributed Drive Electric Vehicles Based on Hierarchical Optimization Control Framework

Directional control of electromagnetic parameters of Fe@Ni nanowires for ultrathin and low-frequency microwave absorbing

How to prepare materials according to the target properties has been a hot research topic. In this paper, the target electromagnetic parameters are obtained according to the performance requirements, and the nanoflower rod-like, low-density mulberry-like and high-density mulberry-like one-dimensional (1D) core–shell structured Fe@Ni(x) nanowires (NWs) are prepared by liquid-phase reduction method. The effective absorption bandwidth (EAB) of sample Fe@Ni(40) in the low-frequency (2–8 GHz) is up to 1.89 GHz (3.1 mm). Sample Fe@Ni(60) is able to reach a maximum EAB of 3.18 GHz at a thickness of 0.9 mm. Concisely, the sample has the ability to absorb microwaves in low frequency bands and ultra-thin thicknesses. The reason can be attributed to the strong magnetic coupling brought by the bimetallic composition to strengthen the resonance level and the excellent 1D core–shell structure to enhance the efficiency of polarization loss. In conclusion, Fe@Ni(x) provides a technological route for the preparation of low-frequency and ultra-thin-thickness absorbers.

Random access vision: an imaging method to observe arbitrary and multiple gaze directions in frame-by-frame manner

In robot vision, it is often desired to measure an area larger than the field of view of the camera, so the camera tends to be mounted on a mechanical pan/tilt platform. However, such mechanisms have a non-negligible response time compared to the frame rate of the camera. In this paper, we describe what we believe to be a new method that allows arbitrary and multiple gaze directions to be observed in a frame-by-frame manner based on a resonant mirror and a lock-in pixel image sensor. In the proposed method, while the gaze direction oscillates due to the resonance mirror, the image sensor makes an exposure of several hundreds of nanoseconds every time the gaze passes through the direction to be captured, and accumulates the captured signals. A prototype system was developed using a lock-in pixel image sensor with four image storage units called taps and a resonant mirror with a resonant frequency of 12 kHz. The system achieved both arbitrary control of the gaze direction in a frame-by-frame manner, and simultaneous capturing of four images with arbitrary gaze directions also in a frame-by-frame manner.