Good Control Strategy Research Articles

Effective biological control of chickpea rabies (Ascochyta rabiei) through systemic phytochemical defenses activation by Trichoderma roots colonization: From strain characterization to seed coating

Chickpea (Cicer arietinum) is a legume of great economic and agricultural importance worldwide, whose crop is severely affected by rust or Ascochyta blight, caused by the fungus Ascochyta rabiei. The fungal genus Trichoderma includes several species widely characterized as effective biological control agents against crop pathogens. First, this work characterized several species of the genus Trichoderma as potential biological control agents of A. rabiei directly (in vitro confrontation) or indirectly in chickpea plants (activation of systemic resistance), selecting T. harzianum EN1 as the most efficient strain. Subsequently, different materials were tested as coatings to apply the T. harzianum conidia on chickpea seeds, determining that gum arabic at 1 % concentration was the one that most promoted the germination of conidia and seeds. The third phase of the study was based on the application of the coating and T. harzianum conidia on chickpea seeds and to study plant survival after infection with the pathogen A. rabiei, characterizing root colonization by Trichoderma and systemic hormonal and metabolic changes related to the induction of systemic defenses. The treatment of chickpea seeds with gum arabic and T. harzianum conidia was found to increase Trichoderma-root colonization and to improve plant survival. The induction of systemic ethylene- and melatonin-mediated resistance, which led to the accumulation of nicotinic acid in plant tissues, was considered the cause of such a protection. Therefore, T. harzianum applied as seed coating with gum arabic could be a good biological control strategy against A. rabiei on chickpea, due to the induction of systemic resistance.

Complex dynamics of a nonlinear impulsive control predator-prey model with Leslie-Gower and B-D functional response

<abstract><p>A good pulse control strategy should depend on the numbers of pests and natural enemies as determined via an integrated pest control strategy. Taking this into consideration, here, a nonlinear impulsive predator-prey model with improved Leslie-Gower and Beddington-DeAngelis functional response terms is qualitatively analyzed. The existence of a periodic solution for pest eradication has been obtained and the critical condition of global asymptotic stability has been established by using the impulsive differential equation Floquet theory. Furthermore, the conditions for the lasting survival of the system has been proved by applying a comparison theorem for differential equations. Additionally, a stable positive periodic solution has been obtained by applying bifurcation theory. To understand how nonlinear pulses affect the dynamic behavior of a system, MATLAB was used to conduct numerical simulations to show that the model has very complex dynamical behavior.</p></abstract>

An Objective Holographic Feedback Linearization Based on a Sliding Mode Control for a Buck Converter with a Constant Power Load

As a typical load, the constant power load (CPL) has negative impedance characteristics. The stability of the buck converter system with a mixed load of CPL and resistive load is affected by the size of the CPL. When the resistive load is larger than the CPL, the buck converter with the output voltage as an output function is a non-minimum phase nonlinear system, because its linear approximation has a right-half-plane pole. The non-minimum phase characteristic limits the application of many control techniques, but the objective holographic feedback linearization control (OHFLC) method is a good control strategy that can bypass the non-minimum phase system and make the system stable. However, the traditional OHFLC method, in designing the controller, generally uses a linear optimal quadratic design method to obtain a linear feedback control law. It requires a state quantity component with a one-order relative degree to the system. But it is not easy to find such a suitable state quantity with a one-order relative degree to the system. In this paper, an improved OHFLC method is proposed for Buck converters with a mixed loads of CPL and resistive loads, using the sliding mode control (SMC) theory to design the controller, so that the output state quantity components with different relative degrees to the system can be used in the holographic feedback linearization method. Finally, the simulation and experimental results also demonstrate that this method has the same, or even better, dynamic response performance and robustness than the traditional OHFLC method.

Work Ethics Practices and Employee Retention Towards Economic Recovery in the Brewery Industries of Lagos Metropolis, Nigeria

The study investigated work ethics practices and employee retention in the manufacturing industries in Lagos, Nigeria with focus on the Nigerian Breweries, Lagos as the unit of analysis. The study identified work ethics practices found operational to include integrity accountability, professionalism, and respectfulness. The corresponding relationship between these work ethics practices and employee retention was also evaluated with the view to providing information on how work ethics practices influence employee retention. The study made use of primary data with the aid of a structured questionnaire administered to 300 respondents randomly to elicit information from the selected respondents. It was found that integrity as a practice was prevalent among other practices found to be operational in the area of study and also found that there exists a significant positive relationship among all the variables of work ethics practices and employee retention where accountability practice with employee retention (r = 0.546, p 0.05), respectfulness practice with employee retention (r = 0.677, p 0.05), professionalism practice with employee retention (r = 0.658, p 0.05) and integrity practice with employee retention (r = 0.748, p 0.05). it was concluded that work ethics practice is a good cost control strategy to sustain employee retention without incurring additional costs, especially in the wake of economic recession and recovery. Thus, recommended that the management of the Nigerian Breweries should institutionalise work ethics practices and educate employees of the organisation on the essence of the practices.

Sliding Mode with Equivalent Control for Induction Motor Drive Based on Multi-Pulse VSC

In this work, the application of a sliding mode equivalent control for an induction motor drive based on a multi-pulse Voltage Source Converter is proposed. This is accomplished by transforming the squirrel-cage induction motor mathematical model into a block control form. The equivalent control method is applied to the sliding manifold, where the voltages are obtained in the stationary reference frame to control the angular velocity of the motor. In addition, a proportional-integral control is designed and applied to the motor represented in this form in order to make performance comparisons with the equivalent control method. Multi-pulse converters of 6, 12, and 84 pulses are used directly to feed the plant that is being controlled. The outcomes of using these power electronics devices are used to perform comparisons among the velocity tracking performance, control voltages in stationary reference frame, tracking errors, and rejection of external disturbances. Furthermore a dynamic and steady-state analysis of the velocity tracking performance is executed. The energy profiles for the startup, torque variations, and steady-state are also obtained. Additionally, total harmonic distortion values are added. All comparisons are carried out using the established plan for the motor, both with and without the use of power electronics converters, and with both control algorithms. The obtained results demonstrate that the use of a high-quality voltage source converter, along with a good control strategy, allows for a general improvement in the overall system and a significant reduction in energy usage, whilst also reducing controller complexity.

Spatial and temporal variations of the flow characteristics at a tidal stream power site: A high-resolution numerical study

The upcoming commercial development of tidal stream power requires a profound knowledge of tidal streams. In this article, the spatial and temporal variations of the flow characteristics are investigated through numerical simulations, at fine spatial and temporal resolutions. The study highlights the necessity of local site characterisation prior to turbine installation, due to the high spatial variability of the flow characteristics over distances of less than 100 m. The high variability in space and time of the flow characteristics at the scale of a turbine and its impact on the blade angle of attack underscore the relevance of a good blade pitch control strategy. The study of extreme events in term of maximal flow velocity and variations in the flow direction gives insight for the structural dimensioning of future tidal stream power devices.

AFD-Net: Apple Foliar Disease multi classification using deep learning on plant pathology dataset

BackgroundPlant diseases significantly affect the crop, so their identification is very important. Correct identification of these diseases is crucial for establishing a good disease control strategy to avoid time and financial losses. In general, machines can greatly reduce the possibility of human error. In particular, computer vision techniques developed through deep learning have paved a way to detect and diagnose these plant diseases on the leaf.MethodsIn this work, the model AFD-Net was developed to detect and identify various leaf diseases in apple trees. The dataset is from Kaggle 2020 and 2021 and was financially supported by the Cornell Initiative for Digital Agriculture. An AFD-Net was proposed for leaf disease classification in apple trees and the results of the efficiency of the model are compared with other state-of-the-art deep learning approaches.ResultsThe results of the experiments in the validation dataset show that the proposed AFD-Net model achieves the highest values of 98.7% accuracy for Plant Pathology 2020 and 92.6% for Plant Pathology 2021 compared to other deep learning models in the original and extended datasets.DiscussionThe results also indicate the efficiency of the proposed model in identifying leaf diseases on apple trees for major and minor classes, i.e., for multiple classification.

Simulation and analysis of sag control of microgrid inverters

A good inverter control strategy helps to maintain the stable operation of microgrid, and sag control is a common control strategy. Since the traditional sag control has the problem of difficult to stabilize the voltage frequency when switching the load. In this paper, we propose an improved sag control by introducing fuzzy control and linear self-rejecting control techniques into the voltage and current dual-loop structure of sag control, respectively, and build the simulation in Matlab/Simulink. The simulation comparison results show that the linear self-rejecting control has the best performance in stabilizing the voltage and frequency and tracking the reference value during load switching of the microgrid with better robustness than the PI control in the traditional sag control and the improved fuzzy control.

Design and Analysis of ECVT on Electric Powered Vehicles for Determining the Speed Ratio

Electronics Continuous Variable Transmission (ECVT) is a smart transmission that has unlimited gear ratios. By analyzing vehicle conditions, ECVT can choose the most efficient gear ratio. ECVT mode requires a Planetary Gear Set (PGS) as a power splitter. This research will use PGS and double electric motor to combine the ECVT mode with electric vehicles to determine the desired speed ratio. The PGS was designed by an analytical model and simulated using CAD software. The simulation will provide several input variations to get the right speed ratio, such as speed variations and rotational direction. The analytical model obtained a PGS ratio of 1:6 with 19 sun gear teeth, 95 ring gear teeth, 38 planet gear teeth, and a motor power of 47 kW. Simulation results will be applied to build the prototype that will be made with a 3D printer. This study shows that ECVT can be a transmission system for electric vehicles with 2 to 5 levels of transmission, and using double electric motors with small power can replace an electric motor with large power. To obtain maximum efficiency, a good control strategy is needed. The control strategy will be discussed in further research.

Modelling of fouling in a plate heat exchanger with high temperature pasteurisation process

This article discusses the steady-state and transient performances of continuous High-Temperature-Pasteurisation-Process (HTST) - milk plant. The plant comprises of integrated three-stage sections (regeneration, heating and cooling) counter-current gasketted-Plate-Heat-Exchanger (PHE) along with holding-tank, boiler, chiller unit and holding-tube. The conservation of mass and energy principle is applied in modelling the plant. Modelling of heat-exchanger is improved using Log-Mean-Temperature-Difference (LMTD) approach. Using this approach, where a rise of about 1 °C has been observed in the temperature of the heat-exchanger’s heating section, and the transient representation of heat-exchanger is thus improved. Fouling is a major issue in a dairy industry, as it incurs additional energy and cost. Moreover, problems due to fouling of exchangers lead to abnormal flow and temperature profile. This makes the pasteurisation difficult to control. Thus, fouling prediction is vital in grass-root design and even more, in retrofit applications. Therefore, the dynamic-behavior of the plant is also augmented by introducing one-dimensional predictive fouling-model (around a thickness of 2.8 x 10-5 m) in the overall integrated plant. It is observed that the reduction of 0.5 °C in pasteurised milk temperature approximately, reduces the quality of milk. The dynamic-model of HTST process is validated with experimental plant data. The sensitivity analysis of the model is also presented. The results of the integrated model are useful in constructing a good control strategy to improve the overall performance, reliability, efficiency, quality-control and economic benefits of the dairy farm.

Research on the Power Distribution Method for Hybrid Power System in the Fuel Cell Vehicle

The power distribution strategy of hybrid power sources is an important issue for fuel cell vehicles. A good power distribution control strategy can realize the optimal control of the vehicle energy, which can save energy and improve the operating conditions of the power source. Therefore, this article proposes a power distribution strategy. First, in order to solve the problems existing in the existing fuel cell model and the lithium-ion battery model, an improved hybrid power system model with better dynamic performance was established in the Simulink. Second, in order to ensure the durability of the power system, operation constraints are added to the distribution strategy. Finally, the power allocation is regarded as a nonlinear programming optimization problem and solved by a nonlinear programming algorithm. The nonlinear programming algorithm selects the BFGS algorithm. The simulation results of other control strategies in MATLAB show that the proposed power distribution strategy greatly improves the durability of the vehicle and has good adaptability under urban conditions. This distribution method can provide support for the actual application of offline control strategies.

Design and Optimization of Control Strategy to Reduce Pumping Power in Dynamic Liquid Cooling

Abstract Data centers are a large group of networked servers used by organizations for computational and storage purposes. In 2014, data centers consumed an estimated 70 billion kWh in the United States alone. It is incumbent on thermal engineers to develop efficient methods in order to minimize the expenditure at least toward cooling considering the limited available power resources. One of the key areas where electronic cooling research has been focusing, is addressing the issue of nonuniform power distribution at the rack, server and even at package levels. Nonuniform heating at the chip level creates hotspots and temperature gradients across the chip which in turn significantly increases the cost of cooling, as cooling cost is a function of the maximum junction temperature. This challenge has increased the use of temperature sensing mechanisms to help in finding ways to mitigate the gradients. A very effective way to conserve pumping power and address hotspots on the single or multichip modules is by targeted delivery of liquid coolant. One way to enable such targeted delivery of coolant is by using dynamic cold plates coupled with self-regulating flow control device that can control flow rate based on temperature. This novel technology will have more effective implementation coupled with a good control strategy. This paper addresses the development and testing of such control strategy with minimal sensors along with less latency and optimization of the same.

Comparative study of two predatory mites Amblyseius swirskii Athias-Henriot and Transeius montdorensis (Schicha) by predator-prey models for improving biological control of greenhouse cucumber

Suppression of the whitefly Bemisia tabaci (Gennadius) and the thrips Frankliniella occidentalis (Pergande) by the predatory mite Amblyseius swirskii Athias-Henriot on greenhouse cucumbers can be considerably affected by cooler conditions in winter. In this study, this well known mite was tested simultaneously with a more recent predatory mite Transeius montdorensis (Schicha), to find out which of them was better at controlling pests on cucumbers in winter in Mediterranean greenhouses. We developed a mathematical predator-prey model which involved releasing both predators with populations of the two naturally occurring pests in a greenhouse cucumber trial. T. montdorensis provided pest control that was similar to and as effective as that by A. swirskii. T. montdorensis exhibited higher populations than A. swirskii, specifically when climatic conditions were colder. However, as the weather became warmer, the A. swirskii population increased quickly. Therefore, releasing T. montdorensis in winter, followed with releases of A. swirskii in spring, may be a good pest control strategy for greenhouse cucumbers.

Effects of the essential oil from Cymbopogon citratus on mortality and morphology of the tick Haemaphysalis longicornis (Acari: Ixodidae).

Haemaphysalis longicornis is one of the most prevalent tick species across eastern Asia, Australia, and New Zealand, and has been implicated as a vector of several pathogenic agents. This study evaluated the in vitro acaricidal efficacy of Cymbopogon citratus (lemongrass) essential oil on unfed H. longicornis using the adult and nymph immersion test, and the larval packet test. Six concentrations with three replications each of 10, 20, 30, 40, 50 and 60 mg/mL (adults and nymphs) were used, and 2.5, 5, 10, 20, 40 and 80 mg/mL (larvae), with control group (50% ethanol). The adult and nymph mortality rates were 98 and 100% at 50 mg/mL, and 95 and 100% at 60 mg/mL, respectively, whereas the larval mortality rate was 94 and 96% at 40 and 80 mg/mL, respectively. Mortality of adult, nymph and larva increased significantly in a dose-dependent manner. The LC50 for adult, nymph, and larva, were 29.21 (95% confidence interval 25.90-32.58), 28.18 (23.78-32.25), and 28.06 (25.57-30.90) mg/mL, respectively. Scanning electron microscopy and light microscopy revealed a disjointed sensilla base from the sockets, cuticular cracks, blocked aeropyles, and shrinking of the midgut. These results showed that C. citratus essential oil could be a good eco-friendly alternative control strategy against ectoparasites like ticks due to its high acaricidal efficacy.

Simulation Evaluation of Threshold-Based Bus Control Strategy Under the Mixed Traffic Condition

Implementing operational strategies is a sustainable and effective way for providing good bus serviceability, but the effects of the strategies on other traffic participants, e.g., cars, have drawn little attention. This paper thus aims to explore the effects of the mutual interference between buses and private cars, when applying a bus control strategy to a regular transit line. Three threshold-based strategies are compared, including (a) holding control (HC); (b) limited boarding control (LBC) and (c) holding combined with limited boarding control (H-LBC). A cellular automaton based model is proposed to depict the interaction between cars and buses, and the model parameters are calibrated using data collected from a real-life bus route in Beijing, China. The control strategies are evaluated by their benefits for three stakeholders involved in the system, including passengers, bus operator and car drivers. Simulation results show that a good bus control strategy does not only improve the efficiencies of bus operating and passenger travel, but also speed up the car running by alleviating traffic congestion. In turn, the car volume is an important factor when setting the optimal parameter for control strategies. Moreover, the comparison suggests that H-LBC outperforms the other two strategies in improving the service level for passengers, buses as well as cars, especially under crowded scenarios.

Active Suspension Control Based on Particle Swarm Optimization

Background: The active suspension can be adjusted in real time according to the change of road condition and vehicle state to enhance the performance of active suspension that has received widespread attention. Suspension control strategies and actuators are the key issues of the active suspension, and are the main research directions for active suspension patents. Objective: The numerical analysis method is proposed to study the performance characteristics of the active suspension controlled by different controllers. Methods: The active suspension control model and control strategy based on particle swarm optimization are established, and two active suspensions controlled by the sliding mode controller and the fuzzy PID controller are proposed. Moreover, two active suspension systems are optimized by particle swarm optimization. Results: The results of the analysis show that the performance of the active suspension is significantly improved compared with the passive suspension when the vehicle runs on the same road. The ride comfort of the active suspension controlled by the fuzzy PID controller has the best adaptive performance when the vehicle runs on different grade roads or white noise roads. The active suspension controlled by the fuzzy PID controller has the best ride comfort. Conclusion: A good control strategy can effectively improve the performance of the active suspension. To improve the performance of the active suspension, it can be controlled by utilizing different control strategies. The results lay a foundation for the active suspension experiments, the dynamic analysis and the optimization design of suspension structure.

Application of Dynamic Programming Algorithm Based on Model Predictive Control in Hybrid Electric Vehicle Control Strategy

A good hybrid vehicle control strategy cannot only meet the power requirements of the vehicle, but also effectively save fuel and reduce emissions. In this paper, the construction of model predictive control in hybrid ele... | Find, read and cite all the research you need on Tech Science Press

Energy Efficient Operation of Light Rail Transit (LRT) System for Kelana Jaya Line via Train Headway Time in Malaysia

With the advancement of new technologies in the rail system, there is a possibility that the energy consumption in the rail system will increase if no efforts are taken to ensure sustainability in the Light Rail Transit (LRT). Therefore, efforts on reducing energy consumption in LRT through optimizing train operational with a good control strategy is crucial to achieve energy saving whilst ensuring efficient use of energy. Train operations such as unchanged dwell time, increase in the length of journey, increase number of trains and train weight are few factors that may increase the traction energy consumption of the LRT system. However, due to frequent changes in passengers commuting between stations, controlling energy consumption will be a challenge as energy consumption keeps fluctuating most of the time coupled with signal delays at intersection and unexpected problem occur along the line. One of the energy saving measures is to control the train headway time. In the context of this research, headway time is defined as the time interval of the tip of one train to the tip of the next one behind it. The regularity of the headway time can be improved by adjusting the dwell time or running time between stations for each train. This paper presents a potential of energy saving at various headway time with increase number of car-train scheduled. Based on the simulation analysis, it indicates that there is a possibility that energy consumption per day can be reduced by5.9% with a reduction of 5% of the current headway time

Study on multi-axis sine vibration test control techniques

This paper describes several key aspects about multi-axis sine vibration test control techniques including the identification of the system frequency response function, synchronization of the input and output signals, the generation of the sinewave, the control algorithm, etc. A multi-axis sine vibration controller is developed based on these key techniques and the major framework of the controller is introduced. Finally, a dual axial experiment is carried out by the controller. The test results show the feasibility of the control algorithm and the good control strategy of the multi-axis sine vibration controller in which the key techniques are realized.

Field and controlled conditions screenings of some faba bean (Vicia faba L.) genotypes for resistance to the parasitic plant Orobanche crenata Forsk. and investigation of involved resistance mechanisms

The parasitic weed Orobanche crenata is a serious constraint to legumes crops in Mediterranean area. In Morocco, heavy O. crenata infestation level was reported in many faba bean fields. Development of resistant faba bean genotypes remains a good long-term control strategy. So, identification of proper resistance sources remains a first step to attend this goal. In this perspective, six faba bean genotypes were subjected to field and controlled conditions (pot and Petri dishes experiments) evaluation for resistance/tolerance to Moroccan O. crenata. Root exudates and their implication on resistance/susceptibility to O. crenata were also investigated. Results showed a wide range of resistance but no complete resistance was detected. Thus, Giza 843, Misr1, and Misr3 genotypes showed good resistance level as compared to both susceptible genotypes Lobab and Aguadulce. Despite infection, the average yield of the three resistant genotypes was two to fourfold higher than the susceptible genotypes. Resistance of faba bean genotypes to O. crenata seems to occur at different levels of the parasite life cycle through: (1) developing lower host root density, (2) reduced attachment of O. crenata on host roots, and (3) delayed development of infection events on host roots. Furthermore, low induction of O. crenata seed germination could not be taken as an indicator of resistance. Based on low infection level and low impact of parasitism on yield and vegetative growth of host plants, Giza 843 was selected as a promising source of resistance to O. crenata which could be introduced into Moroccan faba bean breeding program.