Double-loop System Research Articles

Intelligent finite-time formation control for flapping wing micro aerial vehicles

This paper investigates the intelligent finite time formation control for multiple Flapping wing micro aerial vehicles (FWMAVs) system. Firstly, the translational and the rotational attitude motion equations are proposed based on the Lagrangian equation for FWMAVs. The motion system is decouple into an internal and an external dual loop subsystems. An adaptive neural network estimation algorithm is proposed based on the internal and external double loop system of the coupled model to effectively estimate the uncertainties and the external disturbances of the model. In addition, two effective intelligent control protocols are presented for the translational and the rotational attitude motion subsystem, respectively, by utilizing potential energy function, generalized inverse matrix, and finite-time stability. The main contribution of this paper is the case that, four control objectives are achieved for multiple FWMAVs system, including the estimation of uncertainties, collision avoidance, connectivity preservation, and finite time convergence. Finally, a simulation example of formation tracking control is given by using matlab software in the numerical simulation part, and the effectiveness of the obtained results and the superiority of the control protocol are verified.

Comparison of the effectiveness of thriple-loop and double-loop systems of active shielding of a magnetic field in a multi-storey old buildings

Aim. The issues of comparing the effectiveness of reducing the level of the magnetic field in a five-storey old buildings generated by a single-circuit overhead power transmission lines with a triangular suspension of wires using a thriple-loop and double-loop systems of active screening, which respectively contain three or two compensating windings are considered. Methodology. Spatial location coordinates of the compensating windings and the currents in the shielding windings were determined during the design of systems of active screening based on solution of the maximin vector optimization problem, in whith the vector of objective function is calculated based on Biot-Savart's law. The solution of this problem is calculated based on algorithms of multi-swarm multi-agent optimization. Results. The results of theoretical and experimental comparing the effectiveness of reducing the level of the magnetic field in a five-storey old generated by a single-circuit overhead power transmission lines with a triangular suspension of wires using a thriple-loop and double-loop systems of active screening, which respectively contain three or two compensating windings are presented. Originality. For the first time, the comparison the effectiveness of reducing the level of the magnetic field in a five-storey old using a thriple-loop and double-loop systems of active screening are considered. Practical value. From the point of view of the practical implementation it is shown the possibility to reduce the level of magnetic field induction in a five-storey old buildings to the sanitary standards of Ukraine for real overhead power transmission lines currents with the help of a synthesized double-loop systems of active screening. A double-loop active screening system is simpler in comparison with a thriple-loop active screening system when implementing.

Healthcare Monitoring System for Lymphatic Treatment of Leg Pain: Finding the Related Evidence

To reviews whether healthcare-monitoring systems for lymphatic treatment of leg pain fits any requirement related on its selected classification. Some reviewed articles will be asses to provide a relatable explanation regarding computational intelligence, double-loop feedback theory, healthcare system and healthcare monitoring system. Each criteria provide a basic strength to fit in healthcare monitoring system for lymphatic treatment of leg pain issues. The article comparison will produce profound results with proper justification to be embed in healthcare monitoring system for lymphatic treatment of leg pain. If the comparisons fit certain requirement on healthcare system, it will be applied into the system in a meantime.

Исследование и оптимизация систем управления объектами атомной энергетики на основе имитационных моделей

Matters concerned with development of a fully variable nonlinear simulation model of a double-loop system for automatically controlling the steam pressure in the main steam header (MSH) of a VVER type reactor based NPP power unit’s secondary circuit are considered. A two-stage procedure for optimizing the control system dynamic tuning is described, which uses the linear system frequency analysis method at the first stage and a numerical simulation and optimization method at the second stage, which takes into account the nonlinearities of the control equipment and control object. An evolutionary algorithm of multiparametric optimization with respect to a complex optimality indicator than takes into account the specific requirements for the system is used. The system performance efficiency in a wide range of the power unit outputs has been studied.

Double Loop Network for Combined Heating and Cooling in Low Heat Density Areas

This study investigated a double loop network operated with ultra-low supply/return temperatures of 45/25 °C as a novel solution for low heat-density areas in Denmark and compared the proposed concept with a typical tree network and with individual heat pumps to each end-users rather than district networks. It is a pump-driven system, where the separate circulation of supply and return flow increased the flexibility of the system to integrate and displace heating and cooling energy along the network. Despite the increased use of central and local water pumps to operate and control the system, the simulated overall pump energy consumption was 0.9% of the total energy consumption. This was also an advantage at the design stage as the larger pressure gradient, up to 570 Pa/m, allowed minimal pipe diameters. In addition, the authors proposed the installation of electrically heated vacuum-insulated micro tanks of 10 L on the primary side of each building substation as a supplementary heating solution to meet the comfort and hygiene requirements for domestic hot water (DHW). This, combined with supply water circulation in the loop network, served as a technical solution to remove the need for bypass valves during summer periods with no load in the network. The proposed double loop system reduced distribution heat losses from 19% to 12% of the total energy consumption and decreased average return temperatures from 33 °C to 23 °C compared to the tree network. While excess heat recovery can be limited due to hydraulic issues in tree networks, the study investigated the double loop concept for scenarios with heat source temperatures of 30 °C and 45 °C. The double loop network was cost-competitive when considering the required capital and operating costs. Furthermore, district networks outperformed individual heat pump solutions for low-heat density areas when waste heat was available locally. Finally, although few in Denmark envisage residential cooling as a priority, this study investigated the potential of embedding heating and cooling in the same infrastructure. It found that the return line could deliver cold water to the end-users and that the maximum cooling power was 1.4 kW to each end-user, which corresponded to 47% of the total peak heat demand used to dimension the double loop network.

Research on design method of double-loop electric servo loading system with high-frequency band based on H∞ control strategy

In the hardware-in-the-loop simulation, the goal of electric loading is to realize the accurate tracking of the torque signal and test the performance of the aircraft actuator system. For some high dynamic aircraft, it is necessary to reduce the influence of the surplus torque to increase the system frequency band. This paper introduces a new electric loading system which adopts a double-loop servo motor as the torque loading mechanism. It applies two loops to track the position of the rudder and the aerodynamic load spectrum respectively. For the purpose of reducing the disturbance between two loops of the scheme, a two-DOF H∞ robust controller is designed, which improves the robustness of the system effectively. The simulation results show that the new system increases the upper limit of 25 Hz frequency band of the traditional single-loop system with PID control to the maximum of 40 Hz. The double-loop system thereby meets the technical requirements of the hardware-in-the-loop simulation experiment for high dynamic aircrafts.

Superconducting ‘twin’ qubit

We study a flux qubit consisting of a symmetrical pair of superconducting loops, with two Josephson junctions in each, joined by a common Josephson junction---a `twin' flux qubit. The qubit is capacitively coupled to a transmission line, which allows us to characterize the spectrum of the device by measuring the scattering of propagated electromagnetic waves. We perform a detailed analytical analysis of the double-loop system, revealing its properties, and compare experimental results with numerical simulations. At half-flux quantum bias of both loops, the qubit is protected against global and local magnetic field fluctuations with much less sensitivity to the global field in the second order. The system selection rules allow even-odd transitions and prohibit transitions between even-even or odd-odd levels due to the symmetry of the device.

Theoretical basis of energy efficiency criterion-based optimal control of arc steel-melting furnace modes taking into account 3-dimensional phase current distribution

The purpose of the article is to develop a method for synthesis of the operative adaptive optimal control of the electric mode (EM) of an arc steel-melting furnace (ASF) by energy efficiency criteria based on three-dimensional (3-D) distribution of arc currents. The basis of the created method is the use of operative information on the parameters of 3-D distribution of arc currents and the search for the appropriate optimal control – set points for arc currents of a double-loop system of controlling the electric mode of an arc steel-melting furnace. There have been obtained partial optimality criteria to minimize the specific energy consumption, the steel price per ton, and to maximize the hourly productivity of an arc furnace, as well as an algorithm for operational synthesis and implementation of the optimal control vector according to the chosen criterion, taking into account the model of 3-D current distribution. For the first time, based on the operative on-line control of 3-D arc currents distribution, partial criteria have been obtained for the synthesis of adaptive optimal control of the electric mode of an arc furnace, which makes it possible to comprehensively improve the energy efficiency and electromagnetic compatibility of the arc furnace modes and the electric supply network. The implementation of the created method of adaptive optimal control and the algorithm for its implementation in the structure of a double-loop control system of electric melting mode will allow us, in comparison with the known single-loop control structures, to improve the indices of electrotechnological efficiency and electromagnetic compatibility, and to obtain higher dynamic accuracy of stabilization the electric mode coordinates at the level of the operatively synthesized optimal arc current set points.

A linear ADRC-based robust high-dynamic double-loop servo system for aircraft electro-mechanical actuators

Compared with traditional hydraulic actuators, an Electro-Mechanical Actuator (EMA) is small in size and light in weight, so it has become more widely used. Aerodynamic load on aircraft control surface varies dramatically, and a change of flight environment leads to uncertainties of motor parameters. Therefore, high-dynamic response and strong anti-disturbance capability of an EMA are of great significance for aircraft rudder control and flight attitude adjustment. In order to improve dynamic response and disturbance rejection of an EMA and simplify control parameters tuning, a robust high-dynamic servo system based on Linear Active Disturbance Rejection Control (LADRC) is proposed for an EMA employing a Permanent Magnet Synchronous Motor (PMSM). Firstly, total disturbances of the EMA are analyzed, including parameter uncertainties, load variation, and static friction. A disturbance observer based on a reduced-order Extended State Observer (ESO) is designed to improve the anti-interference ability and dynamic performance. Secondly, the servo control architecture is simplified to a double-loop system, and a composite control of position and speed with acceleration feed-forward is presented to improve the EMA frequency bandwidth. Thirdly, the ideal model of the EMA is transformed into a simple cascade integral form with a disturbance observer, which makes it convenient to analyze and design the controller. Robustness performance comparisons are realized in frequency domain. Finally, simulation and experimental results have verified the effectiveness of the proposed strategy for EMAs.

Investigation of Steady-State Heat Extraction Rates for Different Borehole Heat Exchanger Configurations from the Aspect of Implementation of New TurboCollector™ Pipe System Design

When considering implementation of shallow geothermal energy as a renewable source for heating and cooling of buildings, special care should be taken in the hydraulic design of the borehole heat exchanger system. Laminar flow can occur in pipes due to the usage of glycol mixtures at low temperature or inadequate flow rates. This can lead to lower heat extraction and rejection rates of the exchanger because of higher thermal resistance. Furthermore, by increasing the flow rate to achieve turbulent flow and satisfactory heat transfer rate can lead to an increase in the pressure drop of the system and oversizing of the circulation pump which leads to impairment of the seasonal coefficient of performance at the heat pump. The most frequently used borehole heat exchanger system in Europe is a double-loop pipe system with a smooth inner wall. Lately, development is focused on the implementation of a different configuration as well as with ribbed inner walls which ensures turbulent flow in the system, even at lower flow rates. At a location in Zagreb, standard and extended thermal response tests were conducted on three different heat exchanger configurations in the same geological environment. With a standard TRT test, thermogeological properties of the ground and thermal resistance of the borehole were determined for each smooth or turbulator pipe configuration. On the other hand, extended Steady-State Thermal Response Step Test (TRST) incorporates a series of power steps to determine borehole extraction rates at the defined steady-state heat transfer conditions of 0/−3 °C. When comparing most common exchanger, 2U-loop D32 smooth pipe, with novel 1U-loop D45 ribbed pipe, an increase in heat extraction of 6.5% can be observed. Also, when the same comparison is made with novel 2U-loop D32 ribbed pipe, an increase of 18.7% is achieved. Overall results show that heat exchangers with ribbed inner pipe wall have advantages over classic double-loop smooth pipe designs, in terms of greater steady-state heat extraction rate and more favorable hydraulic conditions.

A robust force feed-forward observer for an electro-hydraulic control loading system in flight simulators

A robust feed-forward observer is proposed for feel force control of an electro-hydraulic control loading system in flight simulators. Combining a velocity feed-forward compensator, the proposed control structure can effectively reduce a disturbance force caused by the control displacement of a pilot to further improve control performances. The electro-hydraulic control loading system is described as a force–displacement impedance system, including a mechanical system and a hydraulic control system, and its dynamic model is established as a double-loop system. Implementation of the proposed controller includes observer model design and filter optimization. Aiming at a force closed-loop which is always a non-minimum-phase system, an effective design method of an approximated inverse model is presented for obtaining an observer model, and it is an biregular transfer function. With the particular observer model, an optimization for the filter of feed-forward observer structure is carried out, by transforming the original structure into a control structure with consideration of modeling error between the obtained observer model and the actual inverse model, which is a 2-independent-controllers structure. Then, an H∞ controller is employed to optimize the transformed structure to indirectly obtain an optimized filter. In order to ensure existence of the H∞ controller for the transformed structure of the feed-forward observer with a biregular observer model, some dynamic characteristics are analyzed and proved. Based on the characteristics, a nominal model modification method is presented to obtain a well-posed H∞ control structure. For designing a performance weighting function, an optimize goal is discussed and its proof is given, and then an algorithm using a bisection method is proposed to further improve the robust performance of the proposed controller. To verify the efficiency of the proposed controller, control performances of the electro-hydraulic control loading system are evaluated in experiments and are compared with those of other controllers, including the proportional–integral–derivative controller, the velocity feed-forward compensator, and the H∞ controller. Experimental results show that the proposed controller can effectively reduce the disturbance force of the electro-hydraulic control loading system, and its impedance characteristics are closer to the ideal force feel model than the other controllers.

Broken-symmetry phases of interacting nested Weyl and Dirac loops

We study interaction-induced broken symmetry phases that can arise in metallic or semimetallic band structures with two nested Weyl or Dirac loops. The odered phases can be of the charge or (pseudo)spin density wave type, or superconductivity from interloop pairing. A general analysis for two types of Weyl loops is given, according to whether a local reflection symmetry in momentum space exists or not, for Hamiltonians having a global PT symmetry. The resulting density-wave phases always have lower total energy, and can be metallic, insulating, or semimetallic (with nodal loops), depending on both the reflection symmetry of the loops and the symmetry transformation that maps one loop onto the other. We extend this study to nested $\mathbb{Z}_2$ nodal lines, for which the ordered phases include also nodal point and nodal chain semimetals, and to spinful Dirac nodal lines. Superconductivity from interloop pairing can be fully gapped only if the initial double loop system is semimetallic.

Flow field optimization for the solar parabolic trough receivers in direct steam generation systems by the variational principle

Direct steam generation (DSG) systems with parabolic trough solar receivers have higher operation temperature and lower investment than double-loop systems. However, they have not been widely employed in commercial plants due to some reasons including the unreliability of solar receivers. In this contribution, in order to improve the reliability, we apply the minimum circumferential temperature difference on the absorber of a solar parabolic trough receiver as the optimization objective, and set the continuity equation, the energy conservation equation and prescribed viscous dissipation rates as constrains to construct a Lagrange function. Then, the variational principle is used to derive the optimization equations that the optimal flow field should satisfy to minimize the circumferential temperature difference. Finally, the convective heat transfer processes in a typical receiver are optimized by the newly derived optimization equations to show the applications. The results show that generating longitudinal vortexes along the main flow in the receiver reduce the circumferential temperature difference effectively, e.g. from 69K to 42K (39% reduction), which provides a guidance for the structural optimization of practical receivers to improve the reliability.

The Research on the System of Double-Holding Water Tank Liquid Level Control with the PID Control

Double tank level control system is the combined control with the host computer and basic instrument, and it realizes the communicative function through monitoring and management. The object of this topic is mainly on double-tank system, then gets the theoretical parameters PID through measuring the characteristic curves of the water level, and finally use MCGS configuration software on PC, for further interaction interface to the parameters tuning of double-holding water tank system and to set the parameters. After reaching the expected target, on the base of routine control PID, we can improve the system function by forming the double loop system and control the liquid level of the water bank better. The two tank liquid level control is made as the core control system by computer and as one kind of fashionable trends.

Fuzzy-Sliding Mode Controller Design for Electric Bicycles

The control system is the core of an electric bicycles. Properties of the controller are among the most important factors determining the performance of the Electric bicycles. In this paper, we design a new energy regenerating brake controller based on the driving and regenerating circuit topology for permanent brushless DC motor (BLDCM). A Fuzzy-Sliding Mode Control (Fuzzy-SMC) algorithm is applied to the inner loop (current loop) of the closed speed-current double loop system to improve the stability and reliability. Experiments and simulations show that the Fuzzy-Sliding Mode controller is superior to the traditional PID controller on many performance measurements including perturbation resistancesteady-state errorresponse speed and the extended driving distance per battery charge.

Noise-immunity of the double-loop system of automatic control

Dynamic transients in a double-loop system of automatic control are under investigations exemplified #by the double-loop frequency-phase system of automatic frequency control. An algorithm of noise-immunity determination of such a system is described. As an example, the pulse and transient characteristics of the double-loop frequency-phase system of automatic frequency control are calculated. The system contains a third-order elliptic low-pass filter, which allows increasing of the system’s noise immunity. Results are obtained both with the help of direct solution of the nonlinear differential equation of the dynamic system in the Mathcad environment and using simulation in the Matlab Simulink environment.

Design of PMSM Servo Control System Based on TMS320F2812DSP

This paper presents a design of PMSM (Permanent Magnet Synchronous Motor) double-loop servo system based on TMS2812DSP hardware platform, programmed by C language in Q format, and using the theory of vector control along with the technique of SVPWM ( Space Vector Pulse-width Modulation). This system can get widely used in the area of motor digital control system, automatic production line, etc, which demands highly precise servo control.

A comment on consecutive-2-out-of- n systems

In 1986, Du and Hwang proved that the probability of failure in a cyclic double-loop system is always minimized by using some fixed arrangement σ ∗ of the items. This arrangement σ ∗ does not depend on the exact values of the failure probabilities of the items, but only on their relative ordering. In 1957, Supnick proved that the travelling salesman problem with certain specially structured distance matrices is always solved to optimality by the same permutation σ ∗ of the cities. We show that the occurrence of the permutation σ ∗ in the statement of both results is not a sheer coincidence: The result of Du and Hwang may be interpreted as a simple special case of Supnick's result.

Ion-chromatographic determination of trace anions with direct sample injection

The influence of the sample volume on the ion-chromatographic determination of anions was examined using various separation columns. Unlike conventionally used columns, Akvilain Al columns exhibit higher capacity factors for weakly retained anions. Thus, increasing the injected sample volume does not result in the masking of peaks of weakly retained anions by the negative system peak. The determination of anions at a level of several Μg/L is possible over a wide pH range. A double-loop system was used to eliminate the effect of residual ions in water used for the preparation of calibration solutions.

EFFECT OF RADICAL PROSTATECTOMY ON SENSORY THRESHOLD AND PRESSURE TRANSMISSION

The mechanisms involved in post-radical prostatectomy incontinence remain unclear despite previous anatomical and functional studies. In addition, the factors responsible for the restoration of continence are not well studied. To improve our understanding of the alterations in continence mechanisms, we prospectively investigated the temporal changes in urodynamic parameters after radical prostatectomy. Cystometry, urethral pressure profilometry and posterior urethral sensory threshold measurements were performed in patients undergoing radical prostatectomy. Preoperative pressure transmission was determined by the maximal urethral pressure divided by the maximal abdominal pressure during cough maneuvers at a bladder volume of 200 ml. Postoperative sensory threshold, pressure transmission (% of pressure transmission), maximal urethral closure pressure and functional sphincter length were measured 6 weeks and 6 months after prostatectomy. These parameters were compared between continent and incontinent patients. Preoperative and postoperative urodynamic studies were completed in 34 patients. The continence rate after 6 weeks was 18% (6 patients) and improved to 82% (28) after 6 months. Preoperatively sensory threshold was 16 +/- 11 mA. After 6 weeks and 6 months, respectively, sensory threshold was significantly higher in incontinent (84 +/- 11 mA., 70 +/- 8 mA.) compared to continent (65 +/- 8 mA., 41 +/- 12 mA.) patients. Preoperative proximal urethral sensory threshold was not correlated with degree of postoperative incontinence determined by pad tests. Pressure transmission was not different in continent and incontinent patients postoperatively. After 6 weeks and 6 months, respectively, pressure transmission was 77% and 91% in continent, and 37% and 58% in incontinent patients (p = 0.04, p = 0.03). Maximal urethral closure pressure was significantly higher in continent patients (35 +/- 6 cm. H2O) compared to incontinent patients (11 +/- 9 cm. H2O). Sphincter length decreased from 50 mm. preoperatively to 24 mm. after 6 weeks and 25 mm. after 6 months. There was no difference in sphincter length between continent and incontinent patients. Posterior urethral sensitivity and pressure transmission are impaired immediately after prostatectomy. An improvement in these parameters after 6 months is associated with the restoration of continence. These observations suggest that urinary continence after radical prostatectomy depends on the integrity of posterior urethral sensation and the efficiency of pressure transmission.