Practical Control Method Research Articles

Characterization and algicidal activity of bacteria from the phycosphere of the harmful alga Karenia mikimotoi.

Harmful algal blooms (HABs) are detrimental to aquatic ecosystems; thus, economical and practical HAB control methods are needed. We analyzed a microbial community closely related to the alga Karenia mikimotoi, which has HABs that can be toxic to aquatic environments. We studied the relationship between algicidal bacteria and the microbial community of K. mikimotoi culture using culture-dependent and culture-independent methods. Bacterial strains Marinobacter sp. (O-7) and Pseudomonas sp. (D-2) were isolated from a K. mikimotoi seawater culture containing a mixed microbial community and determined to have algicidal activity. Both strains produced alga-lysing substances that were toxic to K. mikimotoi. The algicidal extracellular substances produced by D-2 were stable at temperatures ranging from - 80 to 120°C but sensitive to strong acidic/alkaline conditions. The substances produced by O-7 were inactivated at high temperatures and strong alkaline conditions. Extracellular substances produced by O-7 and D-2 caused K. mikimotoi and Prorocentrum donghaiense cell lysis, but no changes or inhibitory effects occurred in two other chlorophyta groups. O-7 and D-2 exhibited significantly greater algicidal activity during the logarithmic growth phase of K. mikimotoi growth compared to the stationary phase. Culture-independent analysis of the microbial community in association with K. mikimotoi was made using Illumina MiSeq sequencing. Phylogenetic analysis showed that Proteobacteria was the dominant bacterial population in the phycosphere of K. mikimotoi, containing Marinobacter sp. and Pseudomonas sp.. The Marinobacter was abundant and accounted for 5.3% of the total. Our results indicate that certain bacterial species from K. mikimotoi culture might be effective for removal of HABs.

Experimental validation of a practical nonlinear control method for hydraulic flight motion simulator

The hydraulic flight motion simulator (HFMS), as a key equipment for hardware-in-the-loop (HWIL) simulation in the field of aerospace, is required to have the ability to accurately simulate the aircraft attitude in the laboratory. However, three model uncertainties including nonlinear friction torque, unbalanced gravity torque and time-varying inertia existing in the outer frame of the HFMS at the same time become a main obstacle to achieving its high-precision position control effect. In this paper, according to identification results of friction torque and gravity torque from experiments, combining with simulation result of time-varying inertia of the outer frame from virtual prototype, a disturbance-observer-based nonlinear robust controller with the model compensation was designed on the basis of the mathematical model. Here, since the model compensation has eliminated the main mismatched uncertainties, dual disturbance observers are only necessary to suppress unmodeled mismatched uncertainties and matched uncertainties. Furthermore, the zero bias of the servo valve was also considered to help controller implementation. Finally, the effectiveness and the practicability of the proposed control method were validated by comparative experiments, which demonstrates that the proposed control method is promising and can be applied in the high-precision position control for the HFMS.

Open-loop control of electrostatic levitation actuators to enhance the travel-range of optical switches

Command shaping is a driving technique for handling the large settling time of the high-Q-MEMS actuators. The strong nonlinearity due to the electrostatic actuation limits the linear operation range in cantilevered or torsional micro-mirrors where command shaping techniques can be applied for positioning. Experimental and simulation results of this research demonstrate the effectiveness of using electrostatic levitation to overcome the actuation nonlinearities and a significant increase in the operation range. The motivation for this research is that applying the nonlinear command shaping causes complexity in command manipulation and requires an accurate knowledge of the nonlinear terms involved in the system model. The large linear operation range generated by the levitating force allows using the practical simple command shaping methods for open-loop control.

Coordination control of frequency and voltage regulation for renewable energy generation

Renewable energy generation has weak disturbance resistance and has insufficient voltage and frequency regulation ability. Aiming at the grid-connected structure of the renewable energy unit converter, this paper analyses the typical control mode of the converter participating in the system voltage and frequency regulation respectively on the basis of the principle and demand of voltage regulation and frequency regulation. Then the practical priority control method is analysed by combining internal active power and reactive power current circle. After that, a coordination control strategy for voltage and frequency regulation is proposed. The strategy optimizes the allocation of active current and reactive current reference value during the operation. It improves the performance of the renewable energy generation, and effectively solves the problems of active power and frequency, reactive power support and voltage, thus enhancing the stability of the power system. Finally, the feasibility of the coordination control is verified by the simulation of permanent magnet synchronous generator in PSCAD/EMTDC.

Research on the Intelligent Control Strategy of the Fuel Cell Phase-Shifting Full-Bridge Power Electronics DC-DC Converter

With the aggravation of energy problems, the development and utilization of new energy has become the focus of all countries. As an effective new energy, the fuel cell has attracted the attention of scholars. However, due to the particularity of proton exchange membrane fuel cell (PEMFC), the performance of traditional PI controlled phase-shifted full-bridge power electronics DC-DC converter cannot meet the needs of practical application. In order to further improve the dynamic performance of the converter, this paper first introduces several main topologies of the current mainstream front-end DC-DC converter, and analyzes their performance in the fuel cell system. Then, the operation process of the phase-shifted full-bridge power electronics DC-DC converter is introduced, and the shortcomings of the traditional PI control are analyzed. Finally, a double closed-loop adaptive fuzzy PI controller is proposed, which is characterized by dynamically adjusting PI parameters according to different working states to complete the intelligent control of phase-shifted full-bridge DC-DC converter. The simulation results in MATLAB/Simulink show that the proposed algorithm has good a control effect. Compared with the traditional algorithm, the overshoot and stabilization time of the system are shorter. The algorithm can effectively suppress the fluctuation of the output current of the fuel cell converter, and is a very practical control method.

Plant-Mediated RNA Interference Expressing dsRNA in Cytoplasm for RNAi-Based Pest Control.

Currently, RNAi-based techniques have exhibited considerable potential for pest control, and considerable progress has been made in identifying a large number of potential target genes in the laboratory. However, applying potential target genes effectively in the field to control pests requires further research. At present, transgenic crops expressing dsRNA are widely recognized as the most practical and economical means of applying RNAi-based techniques using laboratory-identified target genes to control pests in the field. Among the three plant-mediated RNAi techniques, plant-mediated RNA interference expressing dsRNA in cytoplasm is most often considered to be an economical and practical RNAi method for pest control, both in the laboratory and inthe field. In this chapter, I describe the procedure for expressing dsRNA in plant cytoplasm for RNAi-based pest control.

Spacecraft attitude control: Application of fine trajectory linearization control

One of the simplest and most popular methods to design a model-based controller for a nonlinear dynamic system is to apply linear control theories to the linearized model of the nonlinear system. For linearization, first-order Taylor series expansion is a straightforward and widely used method. Although the related linearization method is fairly simple, unfortunately, it causes an error in the linearized model, especially in highly nonlinear systems. Different strategies have been proposed to increase the robustness of linearization-based control methods against the linearization error. All of the methods somehow look at the linearization error as uncertainty or disturbance, which has to be rejected. Generally speaking, the lack of the linearization technique reduces the quality of control. One area in which quality and simplicity of control can be necessary is spacecraft attitude control. For the purpose of spacecraft attitude control, this paper improves a well-known trajectory linearization control (TLC) method as a simple and practical nonlinear trajectory tracking control method using an error-less, fine linearization technique. The modified TLC is then used to develop a control law for spacecraft attitude control with only three tunable control parameters and an approximation of the spacecraft inertia matrix. Finally, due to the elimination of uncertainty caused by the linearization error, in a simple way, the novel attitude controller leads to better performance in comparison with the traditional method. The superiority of the new approach is illustrated in numerical simulations.

Preliminary study of the contraceptive effect of a self-assembling intrauterine device (iUPODs) in mares maintained in a paddock with a fertile stallion

There is an urgent need for practical methods of population control (i.e., contraception and/or sterilization) for free-roaming (i.e., “wild” or “feral”) horses and burros on Western Public Lands in the United States. The objective of this study was to evaluate the contraceptive efficacy of a novel self-assembling three-part polymer-coated magnetic intrauterine device termed as an intrauterine POD (self-assembling; iUPOD) when there are natural breeding conditions when iUPOD use was managed by veterinary professionals with no prior experience with the device. Six mares were administered an iUPOD and were then housed continuously with a fertile stallion for 91 days. The intrauterine POD retention and contraceptive efficacy were 100%. Two mares had prolonged corpus luteum function (for 37 and 91 days) immediately after iUPOD placement. For the estrous cycles of the other mares, the duration of diestrus was 7.8 ± 2.7 days (mean ± S.D.). Four of the mares (67%) became pregnant when in a paddock with the same stallion the year after iUPOD removal. These results are encouraging for use of the iUPOD as a practical and reversible method of fertility control in free-roaming horses and burros.

Noise control in laboratories

ASHRAE Ch. 49 is a leading industry reference in noise control, providing extensive guidance on background noise levels, as well as practical noise control methods. The design guideline for background noise criteria in laboratories ranges from NC 35 to 50 depending on the expected activity. Noise control guidance for laboratories predominantly addresses fume hood design. In practice, recent workplace projects have included laboratory spaces without fume hoods; and background noise levels that are not necessarily controlled by the HVAC systems. The modern definition of “lab” space can include machining and fabrication (makerspaces), workplace server labs (server / chip design), and R&D testing suites for consumer electronics with various microphones/speakers. Accurate estimate of the overall background sound level in the lab is critical in determining appropriate criteria and noise control and avoiding unnecessary cost additions to a project. In some cases (such as makerspaces), ambient noise levels of idling equipment may exceed general ASHRAE guidance and still be acceptable to the occupants, even for a teaching application. In other applications (such as R&D testing), appropriate noise criteria may be significantly lower than ASHRAE’s guidance. This presentation will discuss recent observation and design experiences in evaluating noise levels and noise sensitivity of makerspace, server chip design, and R&D laboratory spaces.

Accurate online MTPA control of IPMSM considering derivative terms

The conventional maximum torque per ampere (MTPA) operation usually neglects the derivative terms of interior permanent magnet synchronous motor (IPMSM) parameters, which significantly influences MTPA control accuracy. In this study, an MTPA control scheme that considers the derivative terms is developed, and a parameter identification strategy that considers the inverter to be non-ideal is developed for the calculation of the IPMSM parameters and derivative terms. In addition, the estimation accuracy of the motor parameters is further improved through the calibration of the nonlinear factors of the inverter. Finally, the effectiveness and accuracy of the proposed method is verified by simulation. This paper proposes practical methods for both inverter parameter estimation and accurate online MTPA control.

Based on minimum fuel consumption mode integrated optimal control of fixed-wing UAV flight propulsion system

Purpose In this paper, with the goal of reducing the fuel consumption of UAV, the engine performance optimization is studied and on the basis of aircraft/engine integrated control, the minimum fuel consumption optimization method of engine given thrust is proposed. In the case of keeping the given thrust of the engine unchanged, the main fuel flow of the engine without being connected to the afterburner is optimally controlled so as to minimize the fuel consumption. Design/methodology/approach In this study, the reference model real-time optimization control method is adopted. The engine reference model uses a nonlinear real-time mathematical model of a certain engine component method. The quasi-Newton method is adopted in the optimization algorithm. According to the optimization variable nozzle area, the turbine drop-pressure ratio corresponding to the optimized nozzle area is calculated, which is superimposed with the difference of the drop-pressure ratio of the conventional control plan and output to the conventional nozzle controller of the engine. The nozzle area is controlled by the conventional nozzle controller. Findings The engine real-time minimum fuel consumption optimization control method studied in this study can significantly reduce the engine fuel consumption rate under a given thrust. At the work point, this is a low-altitude large Mach work point, which is relatively close to the edge of the flight envelope. Before turning on the optimization controller, the fuel consumption is 0.8124 kg/s. After turning on the optimization controller, you can see that the fuel supply has decreased by about 4%. At this time, the speed of the high-pressure rotor is about 94% and the temperature after the turbine can remain stable all the time. Practical implications The optimal control method of minimum fuel consumption for the given thrust of UAV is proposed in this paper and the optimal control is carried out for the nozzle area of the engine. At the same time, a method is proposed to indirectly control the nozzle area by changing the turbine pressure ratio. The relevant UAV and its power plant designers and developers may consider the results of this study to reach a feasible solution to reduce the fuel consumption of UAV. Originality/value Fuel consumption optimization can save fuel consumption during aircraft cruising, increase the economy of commercial aircraft and improve the combat radius of military aircraft. With the increasingly wide application of UAVs in military and civilian fields, the demand for energy-saving and emission reduction will promote the UAV industry to improve the awareness of environmental protection and reduce the cost of UAV use and operation.

Adaptive Cylindrical Wireless Metasurfaces in Clinical Magnetic Resonance Imaging.

The signal-to-noise ratio (SNR) is one of the most important criteria for evaluating the image quality in magnetic resonance imaging (MRI), and metasurfaces with unique electromagnetic properties provide a novel method for SNR improvement. However, their applications in clinical MRI are highly restricted by the inhomogeneous enhancement of the magnetic field and interference in the radio frequency (RF) transmitting field. In this study, an adaptive cylindrical wireless metasurface (ACWM) with homogeneous field enhancement and adaptive resonant modes is reported. The ACWM automatically switches its resonant modes between the partial (transmitting period) and whole (receiving period) resonance, which enables it to not only eliminate the interference in RF transmitting field, but also greatly enhance the SNR. Its adaptability also makes the ACWM applicable to all common clinical sequences without any modifications in the scan parameters. The SNR of MRI images of the human wrist, acquired with ACWM, is two to four times compared with the conventional coil. This work offers a practical control method to fill the scientific knowledge gaps between the preclinical research and medical applications for metasurfaces, and suggests a novel and powerful tool for diagnosing and evaluating human diseases.

Controlled growth of in-plane graphene/h-BN heterostructure on a single crystal Ge substrate

In this study, we successfully demonstrate the growth of an in-plane graphene/h-BN (GBN) heterostructure on a single crystal Ge (110) substrate. A group IV semiconductor Ge is an appropriate catalyst for the epitaxial growth of both graphene and h-BN. Thus, by sequentially introducing ammonia borane (NH3-BH3) and methane using two-zone low-pressure chemical vapor deposition (LPCVD), we obtained an in-plane GBN heterostructure. Based on microscopic and spectroscopic analyses, we confirmed that the edge of the pre-synthesized h-BN domains provides plentiful nucleating sites for the lateral epitaxial growth of graphene. Furthermore, we systematically controlled the area and density of h-BN domains in GBN and observed a change in the electrical conductivity of GBN based on the ratio of conducting graphene and insulating h-BN. This result conforms to the percolation theory of two-dimensional materials (2DMs). We believe that our synthetic approach could be a practical method for large-scale synthesis and property control of in-plane heterostructures and can be applied to various types of 2D heterostructures—potentially useful in a wide range of electronic applications.

Surface roughness effect on cylinder vortex-induced vibration at moderate Re regimes

The marine riser is the key equipment connecting the floating platform with the seabed wellhead, and the vortex-induced vibration (VIV) is the main cause of its fatigue damage, which contains complex and substantial dynamics content. Marine risers are operated for a long time. As time goes by, marine organisms will attach on the marine riser surfaces, thus significantly affect their surface roughness of the riser. The increased surface roughness makes the dynamic characteristics of the riser VIV more abundant and complex, including jumping, multi-frequency vibration, broadband vibration, resonance and other dynamic contents. In this study, based on the bidirectional fluid-structure coupling method of computational fluid dynamics (CFD) and computational structure dynamics (CSD), the modified model of rough wall velocity gradient is introduced, and the calculation program of a rough cylinder wall velocity gradient is compiled and embedded into the numerical calculation program of a smooth cylinder VIV to construct the numerical calculation program of a rough cylinder VIV. The program is used to study effects of various key parameters, including surface roughness, and inflow velocities, on the vibration response characteristics, dynamic characteristics, wake vortex shedding patterns and vibration trajectories of a rough cylinder. The differences of VIV characteristics are systematically studied to reveal the nonlinear dynamic behavior of a rough cylinder VIV, such as jumping, multi-frequency vibration, resonance, etc. The influence mechanism of surface roughness on a cylinder VIV is explored to provide a scientific theoretical basis and a practical engineering method for vibration control of a rough marine riser.

An adaptive dynamic inversion control method based on improved piecewise constant for flight control system

To overcome the lack of robustness of the nonlinear dynamic inversion (NDI) control, a simple and practical adaptive NDI control method based on an improved piecewise constant is proposed in this paper to enhance its robustness to disturbances and improve the accuracy of response tracking. Firstly, reasonable assumptions and analyses are made for the system with the influence of disturbance. Secondly, an improved piecewise constant adaptive NDI control method suitable for general flight control systems is proposed. The stability of the control system with disturbance and the error convergence range of the improved piecewise constant adaptive control are proved and analyzed theoretically. Finally, taking into account the fighter actual control requirements, the angular rates control strategy is given, and the proposed method is applied to the angular rates flight controller design. Matlab simulations are carried out under the disturbance of the actuator failure and the sudden change of the center of gravity, and the robustness and dynamic performance of the controller designed based on the present method is compared and verified. The results illustrate that our present method has stronger robustness and higher control accuracy.

A novel oral rabies vaccine enhances the immunogenicity through increasing dendritic cells activation and germinal center formation by expressing U-OMP19 in a mouse model

ABSTRACT Rabies remains a public health threat in most parts of the world. Dogs, especially stray dogs, are the main sources of rabies transmission in developing countries, while wild animals are primarily responsible for the spread of rabies in developed countries and play an emerging role in rabies transmission in developing countries. Oral vaccination is the most practical method for rabies control in these animals, and the greatest challenge for oral vaccination is the hostile environment and large quantity of proteases in the gastrointestinal tract. In the present study, a promising adjuvant with potential protease inhibitory activity, unlipidated outer membrane protein 19 (U-OMP19), was inserted into the genome of the recombinant rabies virus (rRABV) strain LBNSE, designated LBNSE-U-OMP19, and the immunogenicity of LBNSE-U-OMP19 was investigated. LBNSE-U-OMP19 could potentially protect viral glycoprotein from digestion by gastrointestinal fluids in vitro. The expression of U-OMP19 attenuated viral pathogenicity by restricting viral replication in the central nervous system (CNS) and repressing the production of inflammatory chemokines and cytokines. After oral vaccination, LBNSE-U-OMP19 recruited dendritic cells (DCs), follicular helper T (TFH) cells and germinal center (GC) B cells, promoted the formation of GCs, and increased the population of plasma cells in immunized mice, resulting in higher levels of RABV-neutralizing antibodies and better protection in mice immunized with LBNSE-U-OMP19 than in those immunized with the parent virus LBNSE. Together, our data suggest that LBNSE-U-OMP19 is a promising candidate for oral rabies vaccines.

Trypanotolerance Sheko cattle: an option for sustainable control of bovine trypanosomiasis

Abstract Trypanosomiasis is an impediment to cattle production and other agricultural development in tsetse-infested areas. It is a severe parasitic disease that causes loss in the production and performance of cattle. Hence, the aim of this paper is to review trypanosomiasis control options with emphasis on the use of trypanotolerant Sheko cattle breed for sustainable management of bovine trypanosomiasis in tsetse infested areas. Several methods have been used to control trypanosomiasis through the use of trypanocidal drugs and the management of the vector, tsetse fly. Tsetse fly controls require expensive insecticides and have adverse environmental consequences. Trypanocidal drugs are commonly used and considered a practical trypanosomiasis control method. However, the rise in trypanocidal drug resistance has rendered this option ineffective. The possibility of developing and using a vaccine against trypanosomiasis currently remains out of reach as Trypanosoma periodically undergo antigenic variation. In the absence of a vaccine, presence of trypanocidal drug resistance, and the lack of sustainable tsetse fly control measures demand the need to use trypanotole-rant cattle breeds. The Sheko breed which is found only in southwestern Ethiopia displays considerable natural resistance to tsetse-transmitted trypanosomiasis. This genetic resource provides sustainable solution for challenges related to trypanosomiasis. These cattle have a low level of parasitemia and are able to maintain a good packed cell volume (PCV) compared to other indigenous breeds. As several trypanosomiasis control methods are ineffective, the use of trypanotolerance cattle like Sheko breed in tsetse-fly-challenged areas was suggested.

Factors influencing the occurrence of fall armyworm parasitoids in Zambia

Invasive alien species have environmental, economic and social impacts, disproportionally threatening livelihood and food security of smallholder farmers in low- and medium-income countries. Fall armyworm (FAW) (Spodoptera frugiperda), an invasive insect pest from the Americas, causes considerable losses on maize to smallholder farmers in Africa since 2016. The increased use of pesticides to control FAW in Africa raises concerns for health and environmental risks resulting in a growing interest in research on biological control options for smallholder farmers. In order to evaluate the occurrence of local natural enemies attacking FAW, we collected on a weekly basis FAW eggs and larvae during a maize crop cycle in the rainy season of 2018–2019 at four locations in the Lusaka and Central provinces in Zambia. A total of 4373 larvae and 162 egg masses were collected. For each location and date of collection, crop stage, the number of plants checked and amount of damage were recorded to analyse which factors best explain the occurrence of the natural enemy species on maize. Overall parasitism rates from local natural enemies at each location varied between 8.45% and 33.11%. We identified 12 different egg-larval, larval and larval-pupal parasitoid species. Location, maize growth stage, pest density and larval stage significantly affected parasitoid species occurrence. Our findings indicate that there is potential for increasing local populations of natural enemies of FAW through conservation biological control programmes and develop safe and practical control methods for smallholder farmers.

Optimised controlled charging of electric vehicles under peak power‐based electricity pricing

This study presents a practical control method for electric vehicle (EV) charging optimisation for detached and attached houses. The developed EV charging control method utilises real-time measurements to minimise charging costs of up to two EVs in a single household. Since some Finnish distribution system operators have already launched peak power-based distribution tariffs for small-scale customers and because there is a lot of discussion on this kind of tariff development, the control method considers peak power-based charges. Additionally, the proposed smart charging control method utilises charging current measurements as feedback to reallocate unused charging capacity if an EV does not utilise the whole capacity allocated for it. The control method is implemented and tested with commercial EVs. The conducted hardware-in-the-loop simulations and measurements confirm that the control method works as intended. The proposed smart charging control reduces EV charging electricity distribution costs around 60% when compared to the uncontrolled EV charging.

A QFT ROBUST CONTROLLER AS A REMEDY FOR TRMS

Control of a Twin Rotor Multi-input Multi-output System (TRMS) is not a simple work. Because it has complex nonlinear dynamics, cross-coupling, uncertainties, and instability. This paper provides a practical method for control of a TRMS, named Quantitative Feedback Theory (QFT) as one of the robust approaches. Firstly, the TRMS set and modeling procedure are introduced. Secondly, the nonlinear and linear equations of electrical and mechanical parts in both vertical and horizontal planes are presented. Next, using the QFT method, a controller is designed for motion in each plane. Finally, the robustness of the control strategy is illustrated by simulations of vertical and horizontal motions, including controller and pre-filter in the presence of uncertainties. The results demonstrate that the proposed robust controller can guarantee the system stabilization, as well as pitch and yaw tracking of TRMS.