ISOLATION OF MICROPLASTICS FROM FRESHWATER MACROINVERTEBRATES IN THE DANUBE RIVER

The study was conducted on the Danube River, within the project Joint Danube Survey 3 (JDS3). The main aim was to estimate the quantity of microplastics in aquatic ecosystems through passive biological monitoring. Three freshwater species were used for microplastic (MP) isolation from different taxonomic groups of organisms: Mollusca, Oligochaeta, and Chironomidae (Diptera), with the following species: Lithoglyphus naticoides (C. Pfeiffer, 1828), Limnodrilus hoffmeisteri (Claparede, 1862), and Chironomus acutiventris (Wülker, Ryser & Scholl, 1983), respectively. The samples were collected from 6 sites along the Danube River where 540 specimens were examined. The samples were digested by alkaline method (incubation in 10% KOH solution at 60 ⁰C for 24 h) and filtered through a mill silk, 10 µm mesh size. Collected particles were categorized as: fibre, hard plastic, nylon, rubber, or miscellaneous. Categories were divided into subcategories based on the coloration of the particles. Particles ingested by organisms were represented mostly by fibres and fragmented hard plastics, within the size range were from 0.03 to 4.87 mm. A total of 678 MP particles were collected with an average of 4.64 ± 1.59; 1.64 ± 0.46 and 1.24 ± 0.34 items/organism isolated from L. hoffmeisteri, L. naticoides and C. acutiventris, respectively. According to results, L. hoffmeisteri, L. naticoides and C. acutiventris could be used as proper bioaccumulators of MP pollution in the Danube River

Active disturbance rejection control for unmanned tracked vehicles in leader-follower scenarios: discrete-time implementation and field test validation

This paper presents a systematic design of an active disturbance rejection control (ADRC) system for unmanned tracked vehicles (UTVs) in leader-follow formation. Two ADRC controllers are designed for the lateral and the longitudinal channels of the UTV based on control errors in the cross-track and the along-track directions. Through simulations, the proposed ADRC approach is first shown to outperform the conventional PI/PID controllers in scenarios involving sudden changes in the leader motion dynamics, slippage disturbances, and measurement noise. Then, a comprehensive experimental validation of the proposed leader-follower control is performed using a laboratory UTV equipped with a camera and laser sensors (to enable the calculation of error signals). In order to provide more effective interaction between the human (leader) and the UTV (follower) during the leader-follower task, a camera-based subsystem for human pose recognition is developed and deployed. Finally, the experimental results obtained outdoors demonstrate that the proposed ADRC-based leader-follower UTV control system achieves high tracking capabilities, robustness against slippage disturbances, and adaptability to changing environmental conditions

FUZZY MODEL REFERENCE ADAPTIVE CONTROL OF VELOCITY SERVO SYSTEM

The Implementation of fuzzy model reference adaptive control of a velocity servo system is analysed in this paper. Designing the model reference adaptive control (MRAC) and the problem of choosing adaptation gain is considered. Tuning the adaptation gain by fuzzy logic subsystem and a simple synthesis procedure of fuzzy MRAC are proposed. Several simulation runs show the advantages of fuzzy MRAC approach. Experimental validation on laboratory speed servo is realized by the acquisition system. Results confirm benefits of proposed controller comparing to standard MRAC

Nonlinear Extended State Observer based Active Disturbance Rejection Control of a Laser Seeker System

In this paper, the laser seeker control problem is solved in the framework of active disturbance rejection control (ADRC). The considered problem, which consists of laser seeker stabilisation and target tracking, is expressed here as a regulation problem. A nonlinear extended state observer (NESO) with varying gains is used to improve the performance of linear ESO (LESO), and thus enable better control performance in both transient period and steady-state, with lower control effort. Based on a detailed analysis of system disturbances, a special ADRC tuning method is proposed. The stability of the overall control structure is analysed with a description function method. Through comparative simulations LESO-based and the introduced NESO-based ADRC for the laser seeker system, the advantages of the proposed scheme are shown

Microplastics in the Danube River and Its Main Tributaries - Ingestion by Freshwater Macroinvertebrates

This study was carried out at the Danube River and its tributaries during the Joint Danube Survey 4 (JDS4) expedition. Three freshwater benthic species were used to estimate the quantity of microplastics (MPs): Corbicula spp., Limnodrilus hoffmeisteri (Claparede, 1862), and Polypedilum nubeculosum (Meigen, 1804). Following the kick and sweep technique, individuals were sampled using a hand net or dredge. In order to estimate the number of MP articles/individual particles/g wet body mass, the body mass and total length of all specimens were measured. Alkaline (Corbicula spp.and L. hoffmaisteri) and enzymatic (P. nubeculosum) protocols were performed for tissue degradation. All samples were filtered through glass microfiber filters (mesh size 0.5 μm). The particles were photographed, measured, and counted. A total of 1904, 169, and 204 MPs were isolated from Corbicula spp., L. hoffmaisteri, and P. nubeculosum, respectively. To confirm the chemical composition of isolated MPs, a subsample of 46 particles of the fragmented particles from 14 sampling sites was analysed via μ-ATR-FTIR spectroscopy analysis. The particles were characterised as polycarbonate (PC), polyethylene terephthalate (PET), polypropylene–polyethylene copolymer (PP-PE), nylon (polyamide-PA) and cellophane, with the domination of PET

Projektovanje i realizacija upravljačkih sistema sa aktivnim potiskivanjem poremećaja

Active Disturbance Rejection Control (ADRC) is a recently proposed concept, which features high control performances and the minimal dependence on knowledge of the process model. Hence, ADRC represents a suitable solution for the industrial control applications, where the precise mathematical modeling of the process is limited. This dissertation deals with the design and realization of the ADRC controllers. The contribution of the research is reflected in the proposed modifications of the existing ADRC structures, which enable more efficient sinusoidal disturbances rejection and the sinusoidal reference tracking. The high performances and the robustness of the developed algorithms are demonstrated through the frequency domain analysis. Further, the optimal controller parameters tuning method, which is based on the genetic algorithm, is proposed. Compared to the conventional parameter tuning, it has been shown that the optimally tuned system, for the same robustness and noise sensitivity indexes, provides significantly better performances in terms of the external disturbance rejection and the reference tracking. The practical realization of the control systems, using Field Programmable Gate Array (FPGA) hardware, is analyzed. In this context, the features of the modern FPGA chips are considered and a detailed methodology for the control algorithm implementation, by the graphical system-level software tools, is suggested. In this way, the practical realization of the control system and the selection of the optimal hardware structure, as a tradeoff between the system performances and resource occupancy, are simplified. Consequently, the proposed methodology contributes to reducing the gap between FPGA technology and the control system designers. The developed control system solutions are experimentally tested in the laboratory environment on the three-axis didactic radar platform. The obtained results of the axes tracking performances confirm the efficiency of the proposed control algorithm and its FPGA realization

Application of the acquisition card in the identification of position servo

The application of the acquisition card in the identification of the transfer functions of complete position servo systems and their components is described in this paper. A servo system was realized in the laboratory and the acquisition card was used for recording appropriate step responses. The results were processed in the programme package MATLAB in order to get the transfer functions of the components. The open loop and closed loop transfer functions, which are of the crucial importance in the qualitative analysis of control systems, were derived. The verification of the model was done with a comparative analysis of the results from the laboratory and from computer simulations

The behavior of polypyrrole doped with different anions as an ion‐selective electrode

Polypyrrole (PPy) films were electrochemically deposited on glassy carbon from aqueous solutions of different sodium salts (F−, Cl−, NO 3−, HSO 4−). Methods applied were potentiostatic polymerization or cyclic voltammetry. The electrochemical behavior of such electrodes was studied by cyclic voltammetry. The results obtained show that the reaction is localized at the electrode surface for polypyrrole doped with CI− and NO 3−, anions and diffusion‐controlled for F− anions. The polypyrrole films, examined as ion‐selective electrodes in solutions of anions corresponding to the dopant ones, exhibit lower or higher deviation from the Nernstian response depending on the dopant. When polypyrrole doped with HSO 4− was tested, a cationic response was obtained. The chemical exchange process of dopant anion was studied. The results show that this process depends on the nature of the dopant anion and the anion from the solution

On Dealing with Harmonic Uncertainties in the Class of Active Disturbance Rejection Controllers

Informa UK Limited, trading as Taylor & Francis Group. In this work, the problem of governing systems subjected to harmonic uncertainties is addressed. An active disturbance rejection control (ADRC) framework is proposed here with a key component being a novel resonant extended state observer (RESO). In contrary to the conventional ADRC-based solutions, the introduced one gives the ability to directly estimate and mitigate the influence of harmonic uncertainties. By structuring the whole observer-centred control topology into one degree-of-freedom, compact, feedback error-form (similar to industry-proven PID), the proposed approach can be straightforwardly implemented and commissioned across popular industrial control platforms. Its effectiveness is systematically analysed in terms of tracking accuracy, disturbance rejection and noise sensitivity. The new technique is generalised for the class of nonlinear control-affine systems and expressed with three special forms, each one providing certain advantages to control design. Additionally, an experimental case study is conducted, showing superior performance of the proposed solution against a conventional one. Finally, the stability of the developed approach is rigorously proved using singular perturbation theory

Active Disturbance Rejection Control of Torsional Plant with Unknown Frequency Harmonic Disturbance

In this work, a new robust control algorithm is introduced for uncertain systems with harmonic disturbances of unknown frequencies. The proposed solution works under the active disturbance rejection control (ADRC) framework and utilizes a specialized observer for sinusoidal uncertainties, aided with an on-line harmonic disturbance frequency estimator. The entire governing structure is derived in a convenient error-based domain, easily deployable in various industrial control software. The idea behind the introduced approach is general, but is conveyed here using solely a three degrees-of-freedom torsional system, which is considered a benchmark for vibration phenomenon in many mechanical systems. The efficacy of the proposed control scheme is validated with a set of experiments on a laboratory testbed and a theoretical analysis based on theory of singular perturbation