Echo Control Research Articles

Adaptive fuzzy echo state network optimal synchronization control of hybrid–order chaotic systems via reinforcement learning

In this paper, a novel optimal synchronization control scheme for fractional–integer hybrid–order chaotic systems is formulated. To deal with the fractional–order (FO) constraint, a transformation programme is developed and then the master system considered as an FO chaotic system is transformed into an integer–order one. A fuzzy echo state network (FESN) with the advantages of both fuzzy logic system and echo state network is introduced to approximate system uncertainty. Simultaneously, to alleviate the resource pressure, an optimal synchronization control is proposed in the light of the reinforcement learning mechanism, in which critic–actor update laws are constructed through the negative gradient of a positive function with regard to Bellman residual. Compared to typical fuzzy synchronization control, the devised FESN synchronization scheme with the same computational complexity possess superior approximation ability and synchronization performance. Ultimately, three simulation cases are exhibited to check the validity of the proposed approach.

Echo cancellation using Artificial Intelligence technique

To improve the audio quality in telecommunication, echo cancellation was proposed to prevent signals from re-appearing. Generally speaking, the echo canceler first recognizes the original transmitted signal that appears again due to delay in the transmitted or recieved signal. Then, the echo canceler subtracts the echo in the signals. Commonly, echo cancelers are calledacoustic echo cancellation (AEC) in general, whether they aim for acoustic echo, line echo, or both. However, in modern times, new problems have been emerging which require more innovative, more advanced methods to tackle the echo issue. Thus, the paper reviews methods regarding Artificial Intelligence (AI) to improve the current means for echo cancellation. In this paper, we mainly discuss the approaches to echo cancellation, the identification of echo using adaptive AI and the usage of adaptive filters and neural network for echo cancellation. For instance, deep learning approaches can facilitate the issues of AEC (active echo control) and ANC (active noise control),the optimization of LMS algorithm can be achieved by combining Swarm Intelligence (SI), combining adaptive digital filter and recurrent neural network for acoustic echo cancellation etc. Using AI in echo cancellation can help us achieve high-quality, full-duplex telecommunication in modern telephony system.

Echo state network-based adaptive control for nonstrict-feedback nonlinear systems with input dead-zone and external disturbance

This paper addressed the adaptive control problem for non-strict-feedback nonlinear systems with dead-zone and external disturbances. The design methodology integrated the backstepping technique with the approximation of unknown functions using an echo state network (ESN), enabling real-time adjustments. A comprehensive Lyapunov stability study was conducted to confirm the semi-globally uniformly ultimately boundedness (SGUUB) of all signals in the closed-loop system, ensuring that the tracking error converged to a small neighborhood of the origin. The effectiveness of the proposed method was further demonstrated through two examples, and error assessment criteria were utilized for comparisons with existing controllers.

Convergence and Performance Analysis of Classical, Hybrid, and Deep Acoustic Echo Control

Convergence and Performance Analysis of Classical, Hybrid, and Deep Acoustic Echo Control

Alcohol ablation of the heart – Case report

Abstract
 Alcohol septal ablation (ASA) is a minimally invasive, non-surgical treatment for hypertrophic cardiomyopathy. This condition causes the heart tissue to thicken, restricting blood flow. Reduced blood flow causes symptoms such as shortness of breath and fatigue. Alcohol septal ablation restores normal blood flow by damaging and shrinking the thickened tissue. The procedure does not damage normal tissue. Providers perform this procedure on people who have HCM and, despite medication, have symptoms of shortness of breath and/or fatigue with exertion.1
 Alcohol ablation has been successfully used in the ablation of ventricular tachycardiaventricular fibrillation, and atrial fibrillation. 2
 Material and Methods
 The procedure is performed under the control of the Toshiba Infinix discoscope, in the coronary angiography program. Diascopy parameters are 86 kVp, 800 mA, fluoroscopy: 5 fr/sec, radiography 10 fr/sec, pulse width 12 bit, matrix size 1024x1024. The procedure was performed in the RAO 30° CRANIAL 30° projection, and with a magnification of 20 cm. Visipaque 320 contrast agent was used, which was injected via the MEDRAD Avanta automatic injector. Contrast injection parameters were flow rate 2 ml/s and volume 4 ml. A total of 120 ml of contrast agent was given. To confirm the results of AA, ultrasound contrast agent SONOVIEW was used. Monitoring of contrast flow through the myocardium was done with a SIEMENS ultrasound device.
 Case study
 The patient, 65 years old, is hospitalized at the Department of Interventional Cardiology for an invasive cardiac procedure under the diagnosis of hypertrophic obstructive cardiomyopathy. Echocardiography after the procedure: The left atrium is dilated and elongated. Mitral valve morphologically sclerotically changed, functionally mild to moderate MR 2+ (VC 4 min) Left ventricle of regular dimensions, concentrically hypertrophic walls. Type 3 SAM is being verified. Preserved left ventricular systolic function (EF 60%).
 Conclusion
 We present the case of an elderly patient with symptomatic obstructive hypertrophic cardiomyopathy. Despite the modification of drug therapy, significant obstructive pressure in the outflow tract of the left ventricle still persisted. After adequate preparation, septal alcohol ablation is performed with echo control of the procedure. Postprocedurally, the dynamics of cardioselective enzymes are monitored with ultrasound verified hypokinesis of the S2 irrigation area. Due to intermittent complete AV block, a permanent electrostimulator is implanted. At the

Consensus of multiagent with interaction distortions via echo control

This paper studies the discrete-time multiagent consensus problem with kinds of diverse interaction distortions which are related to the states of agents, and a novel dual switching control strategy is proposed, named echo control, to make the system achieve state consensus. The main feature of the echo control strategy is that agents resend the information flows (received from neighbors) to the corresponding neighbor, just like the reflecting of sound waves. In other words, every individual under the echo control strategy is not only the sender and receiver of the information flows, but also the reflector of its neighbors’ messages. In this way, a negative feedback loop is constructed between every two agents, which is designed to ensure the stability of the multiagent system (MAS), and then the agents’ states will converge to a common value. The effectiveness of the echo control protocol is theoretically analyzed, and numerical simulations validate the correctness of the relevant results.

Reinforcement Learning Impedance Control of a Robotic Prosthesis to Coordinate With Human Intact Knee Motion

This study aims to demonstrate reinforcement learning tracking control for automatically configuring the impedance parameters of a robotic knee prosthesis. While our previous studies involving human subjects have focused on tuning the impedance control parameters to meet a fixed, subjectively prescribed target motion profile to enable continuous walking with human-in-the-loop, in this paper we develop a new tracking control solution for a robotic knee to mimic the motion of the intact knee. As such, we replaced the prescribed target knee motion by an automatically generated profile based on the intact knee. As the profile of the intact knee varies over time due to human adaptation, we are presented with a challenging tracking control problem in the context of classical control theory. By formulating the “echo control” of the robotic knee as a reinforcement learning problem, we provide a promising new tool for real-time tracking control design without explicitly representing the underlying dynamics using a mathematical model, which can be difficult to obtain for a human-robot system. Additionally, our results may inspire future studies and new robotic prosthesis impedance control designs that can potentially coordinate between the intact and the robotic limbs toward daily use of the robotic device.

GMA phased array for active echo control of underwater target

Aiming at the special requirements of low-frequency echo control of underwater targets in high pressure environment, a low-frequency miniaturized active control unit with thickness less than 50 mm was designed based on Terfenol-D, a giant magnetostrictive material. Based on that, a kind of light and thin underwater large plate smart acoustic structure was constructed. It was used for low-frequency active echo control of underwater targets. The active control unit was constructed into a flat smart acoustic structure using a 4 × 4 array distributed design. The active control system based on multi-channel adaptive filter was used to test the echo control performance of the flat active acoustic structure, which can achieve significant noise reduction level in less than one second. And the sound absorption coefficient of 0.8 or more can be achieved at a high pressure of 1 MPa. When the sound wave was incident on the surface of the underwater target obliquely from −10° to +10°, the phased array method was used to make the pointing angle of the GMA array consistent with the incident angle, which could control the surface echo of the active structure very well, and the sound absorption coefficient is close to 0.9. The giant magnetostrictive smart structure combined with the active control system is a new type of low-frequency underwater noise reduction technology.

Echo state network-based online optimal control for discrete-time nonlinear systems

This paper investigates the online optimal control problem of discrete-time nonlinear systems using echo state network (ESN)-based adaptive dynamic programming (ADP) method. An online iterative learning algorithm is proposed to solve the partial differential Hamilton–Jacobi–Bellman (HJB) equation in real time. A novel neural networks (NN) critic-actor architecture is presented using two ESNs to implement the ADP method. Then, two online learning laws of the output weights are designed for searching the optimal cost function and control policy. The stability of system and output weights is analysed using Lyapunov approach. Three simulations are given to show the feasibility and effectiveness of the designed algorithm.

Self Made Bio-conduit using the Edwards INSPIRIS RESILIA: A Modern Alternative to Mechanical Prosthesis

Objective: Ascending aortic conduit with mechanical aortic valve prosthesis was the standard therapy for younger people suffering from severe aortic stenosis in combination with aortic aneurysm over many years. In times of TAVI, new concepts of aortic valve therapy are developing. Especially biological valves in younger patients get into focus avoiding lifelong anticoagulation therapy. We report about implantation of a self made bio-conduit using the Edwards INSPIRIS RESILIA biological valve in younger patients. Methods: From 1/2018 until 7/2019 we implanted a self made bio conduit consisting of an Edwards INSPIRIS RESILIA biological valve 23 – 27 mm sewed in a Vascutek vascular prosthesis 2mm oversized onsite in the OR. Patient cohort consisted of 15 patients (11 male, 4 female) aged 55 to 64 years. Conduits were implanted in a typically Bentall procedure with coronary reimplantation. TEE/TTE control examinations were done 7 days and three months after operation. Results: Implantation was uneventful in all patients, intraoperative TEE showed no stenosis, regurgitation or paravalvular leakage. Postoperative course was uncomplicated in 13 cases, we saw one renal insufficiency and one pneumonia, both in regression until discharge. Echo control examinations 7 days and 3 months p.o showed good valve function with low gradients comparable to measured gradients of patients with single AVR using Edwards INSPIRIS RESILIA biological valve. Patients got no anticoagulation therapy with exception of 6 CHD patients treated with ASS. Conclusions: Self made bio-conduit for Bentall procedure using Edwards INSPIRIS RESILIA biological valve in younger patients is a good alternative avoiding need of lifelong anticoagulation therapy, especially in times of TAVI as a low risk redo procedure in case of bioprosthesis failure. KEYWORD: e-PD-39 The authors do not declare any conflict of interest.

P231 Cardiac metastasis mimicking a myocardial infarction

Abstract We present the case of a 79 years old male patient affected by a lung squamous cell carcinoma (T4 N0 M1a) diagnosed in december 2018 with a 5x5 cm mass in the inferior lobe of the left lung close to the pericardium and a second 5 cm mass in the apical lobe of the right lung. TT echocardiography at that time was normal. Treatment with gemcitabine was scheduled with slight progression of the disease at the CT scan control in april 2019 when initial invasion of the left inferior pulmonary vein was detected. An ECG performed during routine control revealed the presence of q waves and ST segment elevation in the inferior leads. The patient was asymptomatic about the heart but the blood tests revealed a slight increase of HS Troponin I. We decided to repeat the TT echo, which showed the presence of a rounded mobile mass of about 3x2.5 cm in the left atrium close to the upper left pulmonary vein and another formation of about 5x2 cm infiltrating the inferior wall of the left ventricle that appeared akynetic. Both metastatic and thrombotic origins were debated and anticoagulant therapy with LMWH was started. We chose to perform a TE echocardiography, which confirmed the presence of the rounded mass in the left atrium, enlarged as compared to the TT evaluation. At the 3D reconstruction, it appeared to come from the left inferior pulmonary vein, completely occluding it, and expanding to the left superior vein, narrowing but not closing its orifice. The mass was well delimitated, disomogenous and vacuolated, thus confirming its likely neoplastic origin. From the trans-gastric view, we confirmed the large infiltration of the inferior wall of the left ventricle. General conditions of the patients quickly deteriorated and he experienced an ischemic stroke. At the TT echo re-evaluation the mass in the left atrium was greatly reduced as compared to the previous control. Cardiac metastases are a rare and frequently clinically silent occurrence; However, in a minority of cases they may present with ECG alterations such as ST-T segment modifications. In neoplastic patients an ischaemic ECG pattern not following its typical progression, without typical symptoms of ischaemia should rise the suspicion of a cardiac metastasis. In our case the abnormalities could be caused by a loss of viable myocardium secondary to the infiltrating mass or by a compression of the right coronary artery. In this context the echocardiography, both TT and especially TE, is a valuable tool that allow to recognize the real cause of these abnormalities and provides useful informations that enable to distinguish neoplastic mass from a thrombus. The ischaemic stroke was probably due to an embolization of the mass from the left atrium, as confirmed by its important reduction at the last echo control. Abstract P231 Figure. ECG abnormalities and TE echo alteration

An Echo State Gaussian Process-Based Nonlinear Model Predictive Control for Pneumatic Muscle Actuators

Pneumatic muscle actuators (PMAs), a kind of soft/compliant actuators, have been attracted a great deal of attention in the studies of rehabilitation robots. However, the nonlinearities, uncertainties, hysteresis, and time-varying features of PMAs bring a lot of difficulties in their high-precision trajectory tracking tasks. In this paper, an echo state Gaussian process-based nonlinear model predictive control (ESGP-NMPC) is designed for the PMAs. The proposed strategy is comprised of an ESGP, which is suitable for modeling unknown nonlinear systems as well as measuring their uncertainties, and a gradient descent optimization algorithm for calculating the control signal sequences. Based on the Lyapunov theorem, characteristics of the closed-loop system are analyzed to guarantee the asymptotical stability. Both simulations and physical experiments are carried out to illustrate the validity of the proposed control strategy. Compared with other conventional methods, the ESGP-NMPC can achieve a better model fitting for the PMA and control performance for the high-precision tracking tasks. Note to Practitioners —High-precision control of pneumatic muscle actuators (PMAs) is a vital problem when PMAs are utilized as actuators of rehabilitation robots since the patient’s safety and the performance of rehabilitation tasks are largely dependent on the accuracy of the actuators. Conventional model-based control approaches usually require relatively accurate identification of system parameters, which is difficult for the PMA, owing to its strong nonlinear and time-varying characteristics. This paper proposes a new model predictive control method based on an echo state Gaussian process that can describe the unknown dynamics of a PMA due to its universal approximation property. Through the optimization method, the controller can be efficiently realized and presents better performances than some comparatives. By applying this approach, it is possible to achieve not only high-precision control of PMAs but also a certain degree of robustness to the load.

Low-Complexity Multi-Microphone Acoustic Echo Control in the Short-Time Fourier Transform Domain

Many modern communication and smart devices are equipped with several microphones, in addition to one or more loudspeakers. Each microphone not only acquires sounds produced in the near-end room, i.e., desired near-end speech, background noise, and other interferences, but also a far-end signal that is reproduced by the loudspeaker(s). This particular type of acoustic coupling, commonly denoted as acoustic echo, can be reduced in a distortionless manner by employing multi-microphone acoustic echo cancellation (MM-AEC) techniques. However, under noisy conditions, the performance of AEC is limited by the echo-to-noise ratio, and additional echo reduction is needed. Further, to ensure high-quality end-to-end communication in noisy environments, background noise has to be reduced as well. To achieve the latter, multi-microphone speech enhancement techniques, such as beamforming (BF), are often used as they are capable of reducing undesired signal components while causing little distortion to the desired near-end speech. In spite of its high computational cost, the most effective solution to reduce acoustic echoes and background noise is to cascade MM-AEC and BF. In this work, a low-complexity multi-microphone echo controller is introduced, which not only combines low-complexity MM-AEC with BF, but also integrates residual echo reduction into the beamformer design.

State-Space Adaptive Nonlinear Self-Interference Cancellation for Full-Duplex Communication

Full-duplex transmission comprises the ability to transmit and receive at the same time on the same frequency band. It allows for more efficient utilization of spectral resources, but raises the challenge of strong self-interference (SI). Cancellation of SI is generally implemented as a multi-stage approach. This work proposes a novel adaptive SI cancellation algorithm in the digital domain and a comprehensive analysis of state-of-the-art adaptive cancellation techniques. Inspired by recent progress in acoustic echo control, we introduce a composite state-space model of the nonlinear SI channel in cascade structure. We derive a SI cancellation algorithm that decouples the identification of linear and nonlinear elements of the composite state. They are estimated separately and consecutively in each adaptation cycle by a Kalman filter in DFT domain. We show that this adaptation can be supported by a-priori signal orthogonalization and decoding of the signal-of-interest (SoI). In our simulation results, we analyze the performance by evaluating residual interference, system identification accuracy and communication rate. Based on the results, we provide recommendations for system design. In case of input orthogonalization, our Kalman filter solution in cascade structure delivers best performance with low computational complexity. In this configuration, the performance lines up with that of the monolithic (parallel) Kalman filter or the recursive-least squares (RLS) algorithms. We show that the Kalman-based algorithm is superior over the RLS under time-variant conditions if the SoI is decoded and in this way the covariance information required by the Kalman filter can be provided to it.

Adaptive echo state network control for a class of pure-feedback systems with input and output constraints

Abstract In this paper, an adaptive echo state network control scheme is proposed for a class of constrained pure-feedback systems, in which both input and output constraints are considered simultaneously. A prescribed performance function characterizing convergence rate, maximum overshoot and steady-state error is employed to enhance the transient tracking performance. Moreover, an improved dynamic surface sliding mode approach is developed by incorporating high-order sliding mode (HOSM) differentiators into each step of controllers design, such that the sluggish effect of the filter performance in conventional dynamic surface control (DSC) can be eliminated. Finally, the unknown nonlinearities including the input saturation dynamics are estimated by using an echo state network, which is easily trained without adjusting the weights between the input layer and the hidden layer. Comparative simulations are provided to illustrate the effectiveness and superior performance of the proposed method.

Management strategy during neonatal/paediatric VV ECMO run

Introduction: Strategy during extracorporeal membrane oxygenation (ECMO) support is guided by available outcome data. Boundaries limiting selection of cases are shifting with advances in ECMO technology, conventional support, and destination therapies. Evolution: Neonatal respiratory ECMO numbers continue to decline due to improved conventional therapies, whereas infants historically excluded from ECMO (for example, ex-premature infants with O2-dependent chronic lung disease and severe RSV) are now successfully supported. ECMO for bridging of children to lung transplant is now established.1 Advances are also being made in mobile ECMO,2 long duration of ECMO support, and ECMO while wide awake. Initiation: Flow requirements and patient or vessel size govern cannula choice. Percutaneous cannulation of vessels with ultrasound guidance is described in all sizes of children, including small infants.3 Serial imaging and ECHO control are needed for optimisation of cannula position and orientation. Transoesophageal ECHO is preferable to transthoracic where available. Reconfiguration of the circuit may prove necessary in some cases and is better done early in the run.4Troubleshooting: Protocol and bundle adherence are the keys to preventing complications. Detection requires vigilance and rigorous checks along with comprehensive handover and tight teamwork. Management is about appropriate escalation and pathway utilisation. Simulation is an essential component of staff training and a powerful tool for reinforcing these points.5Lung recovery: ECMO can be considered the ultimate in “lung rest” techniques. Enhancing lung recovery during the rest provided by ECMO is mainly achieved by attention to fluid balance, pulmonary toilet, and adoption of ventilator rest settings. Bronchoscopy is also particularly useful in this context.6 Other therapies such as prone position, steroid use, surfactant, perfluorocarbon,7 and even individual lung ventilation2 have a role in selected cases. De-cannulation: Patience can be needed when timing the end to VV ECMO support. Removing the sweep gas from the oxygenator can be done simply without having to wean ECMO flow. In more difficult situations, 12–24 h trial off can be used. Radiological lung clearance, improving lung compliance, reduction of sweep gas requirements, and oxygen challenges are all informative in the run up to a decision to trial off. Lung biopsy8 or genetic test results are useful when recovery is absent to help establish futility. Earlier de-cannulation can be indicated in the setting of an intractable or severe complication. Summary: Strategy for management of VV ECMO support is evolving with improvements in ECMO techniques and advances in supporting therapies. A proactive, rigorous but flexible approach to individual cases can deliver excellence.

Performance Evaluation of OSPF and RIP on IPV4 & IPV6 Technology Using G.711 Codec

Migration from IPv4 to IPv6 is still visibly slow, mainly because of the inherent cost involved in the implementation, hardware and software acquisition. However, there are many values IPv6 can bring to the IP enabled environment as compared to IPv4, particularly for Voice Over Internet Protocol (VoIP) solutions. Many companies are drifting away from circuit based switching such as PSTN to packet based switching (VoIP) for collaboration. There are several factors determining the effective utilization and quality of VoIP solutions. These include the choice of codec, echo control, packet loss, delay, delay variation (jitter), and the network topology. The network is basically the environment in which VoIP is deployed. State of art network design for VoIP technologies requires impeccable Interior Gateway routing protocols that will reduce the convergence time of the network, in the event of a link failure. Choice of CODEC is also a main factor. Since most research work in this area did not consider a particular CODEC as a factor in determining performance, this paper will compare the behaviour of RIP and OSPF in IPv4 and IPv6 using G.711 CODEC with riverbed modeller17.5.

Active control of low-frequency underwater echoes using an array of tile projectors

With the introduction of low-frequency active sonar in anti-submarine warfare, there is a growing need for a novel underwater invisibility device that could replace the existing passive anechoic tiles. In this talk, we describe an experiment on active reduction of underwater echoes at low frequencies using an array of tile-shaped projectors. Each tile projector was designed with the aid of finite-element computations and tested in an acoustic tank for transmit voltage sensitivity and directivity. An array of tile projectors, covering a scale model submarine in a large acoustic tank, were driven by control signals that were intended to produce the impedance match between water and the object. Depending on the frequency of the incident wave, echo reduction as large as 6 dB was achieved. [This work has been supported by the Low Observable Technology Research Center program of Defense Acquisition Program Administration and Agency for Defense Development.]

Control of Quantum Echo and Bell State Swapping of Two Atomic Qubits in the Two-Mode Vacuum Field Environment

We investigate quantum echo control and Bell state swapping for two atomic qubits (TAQs) coupling to two-mode vacuum cavity field (TMVCF) environment via two-photon resonance. We discuss the effect of initial entanglement factor 𝜃 and relative coupling strength R=g 1/g 2 on quantum state fidelity of TAQs, and analyze the relation between three kinds of quantum entanglement(C(ρ a ),C(ρ f ),S(ρ a )) and quantum state fidelity, then reveal physical essence of quantum echo of TAQs. It is shown that in the identical coupling case R=1, periodic quantum echo of TAQs with π cycle is always produced, and the value of fidelity can be controlled by choosing appropriate 𝜃 and atom-filed interaction time. In the non-identical coupling case R≠1, quantum echoes with periods of π, 2π and 4π can be formed respectively by adjusting R. The characteristics of quantum echo results from the non-Markovianity of TMVCF environment, and then we propose Bell state swapping scheme between TAQs and two-mode cavity field.

On the Equivalence of Direct Strain Feedback and Lumped Parameter Wave Echo Control for Oscillation Damping of Elastic-Link Arms

The work discusses two control concepts. Both approach oscillation damping for elastic link robotic arms from fundamentally different theoretical directions. Despite their principal difference, the work consolidates both control schemes by mathematically deriving the equivalence of the resulting control laws. This letter demonstrates the practical application of the oscillation damping on a multi-elastic-link experimental setup. With a special emphasis on the influence of static deflections due to gravity, the letter finally compares the damping action as a modulation to the joint position, joint velocity, and joint motor current reference. The comparison leads to recommendations for strain-based oscillation damping of elastic-link arms under gravitational influence.