Exact Controllability Research Articles

Exact Boundary Controllability of Nodal Profile for Nonautonomous Quasilinear Hyperbolic Systems

Exact Boundary Controllability of Nodal Profile for Nonautonomous Quasilinear Hyperbolic Systems

Exact Null Controllability of String Equations with Neumann Boundaries

This article focuses on the exact null controllability of a one-dimensional wave equation in noncylindrical domains. Both the fixed endpoint and the moving endpoint are Neumann-type boundary conditions. The control is put on the moving endpoint. When the speed of the moving endpoint is less than the characteristic speed, we can obtain the exact null controllability of this equation by using the Hilbert uniqueness method. In addition, we get a sharper estimate on controllability time that depends on the speed of the moving endpoint.

Exact boundary controllability of nodal profile for the system of one-dimensional adiabatic flow

In this paper, we study the exact boundary controllability of nodal profile for the system of one-dimensional adiabatic flow by means of the specificity of the entropy S which is constant about the time t. By a constructive method, we realize the exact boundary controllability of nodal profile by controlling the velocity or the pressure on the side without the nodal profile. Moreover, for the case of the infinite time interval, under the suitable assumption, we can obtain that if the nodal profile and the given boundary function possess an exponential or polynomial decaying property, the boundary control possesses the same exponential or polynomial decaying property.

Efficiency and PF Improving Techniques with a Digital Control for Totem-Pole Bridgeless CRM Boost PFC Converters

A totem-pole bridgeless boost converter is one of the most promising topologies for the power factor correction (PFC) stage in high-power applications due to its high efficiency and small number of components. However, due to the totem-pole structure of the field-effect transistor (FET), very high switching loss occurs via the reverse recovery current of the body diode. To solve these problems, critical mode (CRM) control is a good solution to achieve the valley switching technique. With valley switching of CRM control, the switching loss decreases drastically with decreasing turn-on voltage. But, although the CRM control enables valley switching, it is hard to make an exact valley switching control with general zero-voltage detection circuits. In addition, when a frequency limitation scheme is applied to prevent a very high frequency, the switch can operate with hard switching at the boundary of the frequency limitation. Furthermore, the CRM boost PFC has a low PF and high total harmonic distortion (THD) under light-load conditions due to the large negative current resulting from resonance between the inductor and parasitic capacitance. It becomes worse at near-zero input voltage since the resonance current becomes larger near zero-input voltage. Therefore, in this paper, a totem-pole bridgeless boost PFC converter with high efficiency, high PF, and low THD is developed using TMS320F28377 by Texas Instruments. Based on the basic digital structure of the totem-pole bridgeless converter, the proposed controls help with exact valley switching, PF and THD improvement, and frequency limitation. The prototype converter is verified using 90–264 VAC input voltages and 450 V/3.3 kW output specifications.

Design and experiment of high-speed and precise positioning seeding control system for rice seedlings based on dual-position feedback adjustment (DPFA)

To improve the alignment accuracy of the mechanical drum-type rice bowl seedling raising precision seeding line under the high-speed sowing operation state between the seed outlet and the bowl hole. This paper proposes a high-speed and precise positioning seeding control system for rice seedlings based on dual position feedback adjustment (DPFA). Based on Siemens PLC controller, through sensor selection and installation, controller parameter acquisition and calculation, and human–computer interaction software development. We have completed the design of the high-speed and precise alignment seeding control system for rice pot seedlings. Realize the dual position detection of the mechanical drum-type seed wheel and the 406-hole tray. Applying the fuzzy PID controller optimized the dual-position feedback regulation rice pot seedling high-speed and precise alignment planting control system. The response time was shortened to 0.0432 s, the overshoot was 4.5 %, and the adjustment time was 0.1105 s. The sowing test was conducted with sowing speed and height as the main influencing factors and sowing uniformity, leakage rate, and sowing pass rate as the evaluation indexes. The test results show that the sowing speed is within 500 trays/h ∼ 600 trays/h, the sowing uniformity is higher than 65 %, the missed seeding rate is less than 1.5 %, and the qualified rate of sowing is above 94 %. Among them, the maximum sowing uniformity was 66.27 %, the minimum value of missing seeding was 0.89 %, and the sowing qualification rate was 97.06 %. The accuracy rate of material shortage alarms is 100 %. The DPFA-based high-speed and precise alignment sowing control system for rice pot seedlings can realize the exact alignment control function of the mechanical drum-type seedling raising and sowing line.

Controllability of Hilfer Fractional Semilinear Integro-Differential Equation of Order α ∊ (0, 1), β ∊ [0, 1

In this paper, Hilfer fractional differential equation is studied. Firstly, we used Laplace transform and semigroup theory to find the mild solution of the system. Then exact controllability of proposed system is established using the Arzela-Ascoli theorem and Schauder fixed point theorem. To illustrate the developed theory we provide an example at the end.

Exact internal controllability and exact internal synchronization for a kind of first order hyperbolic system

In this paper we investigate the exact controllability and exact synchronization in L2 space for a 1-D first order linear hyperbolic system with internal controls located on some part of the domain. Based on the exact boundary controllability theory, we first use the constructive method to establish the exact controllability by internal controls for a time reversible system with inhomogeneous boundary conditions. The method is then adapted to prove the exact internal null controllability for a general system with homogeneous boundary conditions. These results can be then used to establish the exact internal synchronization for the system, and related subjects are further studied.

Photocatalytic degradation of indigo carmine dye by hydrothermally synthesized graphene nanodots (GNDs): investigation of kinetics and thermodynamics.

Graphene nano dots (GNDs) are an intriguing emerging class of materials at the nano scale with distinctive characteristics and exciting potential applications. Graphene oxide was synthesized in a lab setting using a modified version of Hummers' approach and used as a precursor for synthesis of graphene nano dots. Graphene oxide is then treated through hydrothermal treatment to produce GNDs with exact control over their size and form. Synthesized graphene nano dots were subjected to various instruments to study morphology, crystallinity, size and other properties. UV-visible spectroscopy was used to detect the maximum absorbance of light. For functional group identification, FTIR analysis was conducted. X-ray diffraction analysis explained structural composition and various other parameters i.e., crystal size and diameter, which was further verified by Vesta software. Surface morphology of GNDs was analyzed by scanning electron microscopy. AFM analysis of GNDs demonstrates the topography of the surface. The photo degradation of the indigo carmine dye by the GNDs also demonstrates their superiority as UV-visible light driven photo catalysts. To evaluate the results, the thermodynamics and kinetics of the degradation reactions are examined. The effects of several factors, such as temperature, initial concentration, time, pH and catalyst concentration, are also investigated. The data will be analyzed statistically by regression and correlation analysis using dependent and independent variables, regression coefficient and other statistical techniques.

Syn‐rift tectono‐stratigraphic development of the Thebe‐0 fault system, Exmouth Plateau, offshore NW Australia: The role of fault‐scarp degradation

AbstractThe syn‐rift architecture of extensional basins records deposition from and interactions between footwall‐, hangingwall‐, and axially‐derived systems. However, the exact controls on their relative contributions and the overall variable depositional architecture, and how their sediment volume varies through time, remains understudied. We undertook a quantitative approach to determine temporal and spatial changes in the contribution of fault‐scarp degradation to the syn‐rift tectono‐stratigraphic development of the Thebe‐0 fault system on the Exmouth Plateau (NW Shelf, offshore Australia), using high‐quality 3D seismic reflection and boreholes data. The magnitude of footwall erosion was measured in terms of vertical (VE) and headward (HE) erosion by calculating the volume of eroded material along the footwall scarp. A detailed seismic‐stratigraphic and facies analysis allowed us to constrain the architectural variability of the hangingwall depositional systems and the types of resulting deposits (i.e., fault‐controlled base‐of‐scarp, settling from suspension, and hangingwall‐derived). After addressing the syn‐rift tectono‐stratigraphic framework, we suggest that periods of significant erosion along the Thebe‐0 fault scarp are related to the accumulation of fault‐controlled base‐of‐scarp deposits characterised by comprising a lower wedge with chaotic to low‐continuity reflections. Footwall‐derived deposits characterised by an upward decrease in stratigraphic dip are interpreted as related to periods of reduced fault activity and sustained sediment delivery sourced from the footwall scarp and systems beyond it (e.g., antecedent systems). We then analysed the tectono‐stratigraphic framework and the volumetric comparison between material eroded from the fault‐scarp and accumulated in the basin, aiming to estimate the contribution of fault‐scarp degradation to the hangingwall syn‐rift fill. Our results suggest periods of enhanced fault activity control fault‐scarp degradation variability through time, and we agree with that described by previous researchers—fault throw variability along‐strike regulates the variability in the magnitude of erosion. However, we propose that fault‐scarp degradation timing and its spatial variability are also influenced by the interaction and linkage with adjacent normal faults and by sea level variations. Lastly, we determine broader similarities and differences with a system located in the same fault array (i.e., Thebe‐2 fault system), aiming to give insights into the tectono‐stratigraphic evolution of a broader area and the spatial variability in fault‐scarp degradation.

On the controllability results of semilinear delayed evolution systems involving fractional derivatives in Banach spaces

<abstract><p>The paper investigated the exact controllability of delayed fractional evolution systems of order $ \alpha\in (1, 2) $ in abstract spaces. At first, the exact controllability result is obtained when the nonlinear term $ f $ is locally Lipschitz continuous. Then, the certain compactness conditions and the measure of noncompactness conditions were applied to demonstrate the exact controllability of the concerned problem. The discussion was based on the fixed point theorems and the cosine family theory.</p></abstract>

Inducing Anaesthesia via Exact Feedback Linearization control

The necessity of painless surgery and delivering an accurate dose of drug to induce anaesthesia to the patient is indubitable. Delivering a higher dose to the patient may lead to adverse effects and postoperative complications, while a lower dose obviously leads the patient to regain consciousness during the surgery and in extreme cases even to surgery failure. To overcome such complications during surgeries several research studies revolve around the design of a computer-controlled system to deliver an accurate dose of drug to induce anaesthesia. Therefore this paper aims to introduce an exact linearization of the drug administration model in anaesthesia, without losing too much information about the internal dynamics. This is realised by creating a linear map between the input and output. The control law uses this model and is designed to ensure performances of no overshoot and minimum steady-state error. The control loop is tested on a system with parametric uncertainties (related to patient intra/inter-variability). The simulation results validate the proposed approach and demonstrate its robustness.

Variable-Gain Robust Exact Differentiator-Based Neuro-Adaptive Control Design for Dynamic Wind Power Optimization

Variable-Gain Robust Exact Differentiator-Based Neuro-Adaptive Control Design for Dynamic Wind Power Optimization

Flow-controlled air-jet for in vivo quasi steady-state and dynamic elastography with MHz optical coherence tomography.

Optical coherence elastography (OCE) has been introduced for several medical applications to determine tissue mechanical parameters. However, in order to measure sensitive healthy tissue like brain in vivo, the excitation force needs to be carefully controlled and as low as possible (under 100 μN). Preferably, the excitation should be applied in a non-contact manner. In this work, an air-jet excitation source for this specific purpose has been developed and characterized. The design focus was set on the exact measurement and control of the generated excitation force to better comply with in vivo medical safety requirements during surgery. Therefore, an excitation force control and measurement system based on the applied gas flow was developed. This system can generate short, high dynamic air-puffs lasting fewer than 5 ms, as well as quasi-static excitation forces lasting 700 ms. The force range covers 1μN to 40 mN with a force error margin between 0.1% and 16% in the relevant range. The excitation source, in conjunction with a 3.2 MHz optical coherence system, enables phase-based, dynamic, and quasi steady-state elastography, as well as robust non-contact classical indentation measurements. The presented system is a preliminary prototype intended for further development into a clinical version to be used in situ during brain tumor surgery.

Exact linearization and control of a mobile robot for the inspection of soil resources in Solanum tuberosum crops.

In recent years, the development of robots for agro-industrial applications, such as the cultivation of Solanum tuberosum potatoes, has aroused the interest of the academic and scientific communities. This is due, at least in part, to the complexity of modeling and robustly controlling some dynamics inherent to nonlinear behaviors normally attributed to the different technologies associated with the movement of these autonomous vehicles and their non-holonomic constraints. The different nonlinear dynamics of mobile robots are usually represented by state-space models. However, given some equilibrium and stability characteristics, the implementation of effective controllers for the robust parametric tracking and variation problem requires techniques that allow the operability of robots around regions of stable equilibrium. Feedback linearization control is one such technique that attempts to mathematically eliminate nonlinear expressions from the plant model. However, this technique requires an observable and controllable mathematical model. If there is some relationship between the model inputs and a controlled output that allows the relative degree of the control law to be determined, the controller design and implementation are posed as a linear issue. Flat filters developed from the generalized proportional integral control approach are an alternative that could facilitate the design of controllers for these linearized systems. From these flat filters, it is possible to obtain the transfer function of a controller without relying on the derivatives of the system output. This work proposes the design of a controller via exact linearization and its equivalent flat filter for a robot inspector of the soil resource of S. tuberosum crops in the department of Cundinamarca, Colombia. The actuator motion constraints resulted in a robot with two degrees of mobility and one non-holonomic constraint. Numerical validation of this system suggests that it can be an effective solution to the problem of tracking control at changing references by providing a system capable of navigating through crop rows. The results suggest correct tracking for linear and circular trajectories. However, the control lacks the ability to track spiral-type trajectories.

Exact Consensus Control of Nonlinearly Parameterized Multi-Agent Systems With Unknown Control Directions

Exact Consensus Control of Nonlinearly Parameterized Multi-Agent Systems With Unknown Control Directions

Null controllability of Hilfer fractional stochastic differential equations with nonlocal conditions

<p style='text-indent:20px;'>This paper assesses a class of nonlocal Hilfer fractional stochastic differential equations (NHFSDEs) governed by fractional Brownian motion (fBm). New sufficient condition of exact null controllability for this stochastic setting has been investigated using fractional calculus, fixed point theory and a theory of resolvent operator. The derived result is new because it generalizes several of previously published results. However, the obtained results are proven by an illustration using stochastic partial differential equations to demonstrate the present application characteristic of null controllability. A filter example is demonstrated to make use of resolvent operator in a practical way.</p>

Exact controllability for nonlocal wave equations with nonlocal boundary conditions

Exact controllability for nonlocal wave equations with nonlocal boundary conditions

Green metal matrix composites: a multi-faceted study on Al alloy composites with egg shell powder and silicon carbide as reinforcements

This article is about Green Metal Matrix Composites (GMMCs) produced with aluminum alloys and reinforcements include silicon carbide and eggshell powder. The GMMCs offer a new approach to sustainable materials through the use of ecofriendly reinforcements. A novel class of composites results from a combination of silicon carbide, which has superior mechanical properties, and agricultural waste based eggshell powder. Furthermore, eggshell powder mainly comprised of calcium carbonate lowers its density as well as serves as long-term reinforcement. Silicon carbide enhances their mechanical properties in terms of strength and hardness respectively. This report involves a systematic study using mechanical testing and scanning electron microscopy to explain microstructural evolution and evaluate performance during mechanical loading. Further, wear resistance gives indications on suitability for different industrial applications. Variations in reinforcement contents were done so as to include 3–12% silicon carbide, and 2–8% eggshell powders in the aluminum alloys. Production strictly adhered to guidelines that controlled some variables such as stirring speed and duration which was aimed at achieving exact control. These cast composites were subjected to wear tests, tensile tests, and hardness tests as well as microstructural analysis. EDS-SEM results demonstrate successful incorporation of the reinforcements into the hybrid composites. Unveiling a surprising evenness of distribution of reinforcements throughout the Aluminum matrix through Microstructural examination is amazing. Unique wear behavior trends are presented here. The matrix alloys show mainly adhesive wear while the composites display abrasive wear mediated by reinforcements. This research proposes an eco-friendly method for metal matrix composites, thus advancing sustainable materials and offering hope for strong yet lightweight green materials suitable for aerospace, automotive and other engineering sectors.

Exact controllability of wave equations with internal control in moving boundary domain

Exact controllability of wave equations with internal control in moving boundary domain

An approximation method for exact controls of vibrating systems with numerical viscosity

We analyze a method for the approximation of exact controls of a second order infinite dimensional system with bounded input operator. The algorithm combines Russell’s “stabilizability implies controllability” principle and a finite elements method of order θ with vanishing numerical viscosity. We show that the algorithm is convergent for any initial data in the energy space and that the error is of order θ for sufficiently smooth initial data. Both results are consequences of the uniform exponential decay of the discrete solutions guaranteed by the added viscosity and improve previous estimates obtained in the literature. Several numerical examples for the wave and the beam equations are presented to illustrate the method analyzed in this article.