Adaptive Delay Research Articles

Passivity-based adaptive delay compensation for real-time hybrid tests

This article presents a novel passivity-based adaptive delay compensation scheme for cancelling actuator dynamics in real-time hybrid testing. This scheme uses the energy added to the system by actuation hardware, to quantify a variable delay, which is subsequently used for delay compensation. It offers the advantage of correcting for tracking errors and instability in hybrid tests and can be implemented without any information of the actuator’s dynamics. Thus, it offers an advantage over most conventional actuator dynamics mitigation schemes which require an accurate model of the actuator prior to testing. Experimental results compare the performance of passivity-based adaptive delay compensation with that of a state-of-the-art adaptive delay compensation scheme based on position. It was found that passivity-based adaptive delay compensation continuously updates the delay estimate while the position-based scheme only updates the delay when the system crosses zero. The performance of both schemes was found to be similar for sinusoidal inputs, mitigating phase lags of up to 35.6° at 10 Hz in the hybrid system tested. Passivity-based adaptive delay compensation requires no extra hardware as it can be run on the same hardware used to drive the actuator, enabling an affordable solution applicable to a wide range of hybrid tests.

Torque identification based on LMS adaptive delay inverse system method

In order to relieve the dependence of load estimation upon the prior knowledge of mechanical system, an adaptive delayed inverse model is proposed for identifying the torque time history based on adaptive delay inverse system identification method. The LMS (least mean square) algorithm was used to identify the inverse model of the rotating system, which instead of system characteristic matrix inversion in common determination methods and ill-posed problem is avoided consequently. The adaptive delayed inverse model was used to identify the time-domain torque by analyzing the angular acceleration response data of the working state. The single-point time-domain torque of the bare shaft was identified by the angular acceleration response in the case of noiseless interference. The simulation results illustrate that the recognition results of this method is satisfied. It is proved by the experiment that the method is also feasible to the shaft system with disk coupling. The proposed method can be applied in practical engineering as it is not necessary to grip the mathematical model and system parameters in advance.

Data-Driven Wide-Area Model-Free Adaptive Damping Control With Communication Delays for Wind Farm

The strong nonlinearity, time-varying structure, and complex operating conditions in interconnected power systems with the wind farm deteriorate the control performance of wide-area damping control (WADC) designed by conventional model-based methods. In this paper, an improved model-free adaptive control (MFAC), which employs the pseudo-partial derivative (PPD) to linearize the nonlinear power system dynamically, considering WADC requirements and system disturbances is proposed to damp out the inter-area oscillation for wind farm. In addition, to compensate for communication delays in a wide-area measurement system (WAMS), an adaptive delay compensator (ADC) is employed to reimbursed both constant and variable delays. The proposed controller depends only on online I/O data, which avoids the complicated system modeling process and can adapt to variations of system operating conditions and delay scenarios. Moreover, compared to existing MFAC damping approaches, the proposed approach provides additional advantages for wind farm on managing initial values and the stability region of PPD. The communication delays are compensated, which is not considered in other MFAC-based methods. Finally, case studies with various uncertainties and disturbances are conducted to validate the proposed control strategy.

P1488Autonomic nervous system optimized cardiac resynchronization therapy

Abstract Introduction. Traditional Cardiac Resynchronization Therapy, CRT, relies on bi-ventricular, bi-V, pacing. For left bundle branch block, LBBB, patients with good atrial-right ventricular conduction, A-RVc, alternatives have been proposed that use left-ventricular only pacing, LVoP, with adaptive atrio-ventricular delay, AVD, that is updated every minute from A-RVc measurements. The key advantage is extended device longevity since the RV pacing pulse is not emitted. Purpose. In this paper we present a CRT alternative using fixed AVD LVoP + RV sense trigger (an LV pulse is triggered when an RV depolarization is sensed), RVsT, that can be used with LBBB patients with good A-RVc. Intrinsic RV depolarization is used. The longevity of the device is expected to approach that of a dual chamber device since AVD adaption is not needed. Method. 5 CRT patients with LBBB and good A-RVc, previously programmed to bi-V pacing, were reprogrammed to fixed AVD LVoP + RVsT. The devices are standard CRT pacemakers, CRT-P, with RVsT. They are normally operated in LVoP mode. In response to atrial tachycardia, mode switching to bi-V will be required. So, 3 chamber devices are still required. Results. Nightly at about 02:00 the CRT-P collects Ax-Vs (Ax = As & Ap) statistics for 35 consecutive heart cycles with AVD of 300 ms, while the patient is asleep. A typical plot of these timing statistics at the time of reprogramming to LVoP is shown in Fig. 1. After a self-training period of 2 weeks to 9 months, these statistics coalesce in a narrow range of values, 20 ms wide, as illustrated in Fig. 2 for our super responder (2 weeks). This 20 ms wide pattern persisted for the next 9 months. In the case of the index patient this lasted 3+ years. This persistent A-RVc pattern across all 5 patient can only be explained by a tight dromotropic control by the Autonomic Nervous System, ANS. Fig. 3 illustrates RVsT. As the RVs arrives earlier than the LVp, there is no longer synchronicity improvement since the LVp now follows the RVs immediately. In Fig. 4, we see long periods with high %RVs associated with high heart rates. Increased hemodynamic demand can only be met by increased contractility. Thus inotropic modulation by the ANS is now active and effective. The patients were put on remote monitoring with nightly follow-ups. Over a period of 6.5 months RVs (pre LVp) statistics were collected. A daily median of 11% was reported for this patient. On a particular day, it can be as high as 50%. Dromotropic action to pull in the RVs cannot be explained without concurrent inotropic modulation. Conclusions. Traditional CRT leads to ineffective ANS modulation due to bi-V pacing for >95-98% of the cycles. In our 5 patients the fixed AVD LVoP + RVsT program has allowed nervous system remodeling and the ANS is back in control of hemodynamics. Thus we have ANS optimized CRT! It is an attractive CRT alternative for LBBB patients with good A-RVc since device longevity is also improved. Abstract Figure. Fixed delay LV-only + RVs trigger

Delay Compensation of Demand Response and Adaptive Disturbance Rejection Applied to Power System Frequency Control

In this paper, a modified frequency control model is proposed, where the demand response (DR) control loop is added to the traditional load frequency control (LFC) model to improve the frequency regulation of the power system. One of the main obstacles for using DR in the frequency regulation is communication delay which exists in transferring data from control center to appliances. To overcome this issue, an adaptive delay compensator (ADC) is used in order to compensate the communication delay in the control loop. In this regard, a weighted combination of several vertex compensators, whose weights are updated according to the measured delay, is employed. Generating the phase lead is the most important strategy for these compensators to eliminate the impact of communication delay. Moreover, to overcome the impact of disturbances and uncertainties in power system, an active disturbance rejection control (ADRC) is utilized as the load frequency controller. Being used instead of a PI controller, this robust controller employs an extended state observer to estimate the disturbances and uncertainties and uses a feedback controller to compensate them. The confined iterative rational Krylov algorithm (CIRKA) is employed to reduce the order of the detailed IEEE 39-bus test system model meticulously and facilitate the controller process design. Therefore, a DR control loop, ADC, and ADRC are employed in the LFC to regulate the frequency of the power system in a more efficient way. The simulation results confirm the effectiveness and robustness of the frequency control in presence of communication delay and model uncertainties.

An adaptive delay compensation method based on a discrete system model for real-time hybrid simulation

The identification of delays and delay compensation are critical problems in real-time hybrid simulations (RTHS). Conventional delay compensation methods are mostly based on the assumption of a constant delay. However, the system delay may vary during tests owing to the nonlinearity of the loading system and/or the behavioral variations of the specimen. To address this issue, this study presents an adaptive delay compensation method based on a discrete model of the loading system. In particular, the parameters of this discrete model are identified and updated online with the least-squares method to represent a servo hydraulic loading system. Furthermore, based on this model, the system delays are compensated for by generating system commands using the desired displacements, achieved displacements, and previous displacement commands. This method is more general than the existing compensation methods because it can predict commands based on multiple displacement categories. Moreover, this method is straightforward and suitable for implementation on digital signal processing boards because it relies solely on the displacements rather than on velocity and/or acceleration data. The virtual and real RTHS results show that the studied method exhibits satisfactory estimation smoothness and compensation accuracy. Furthermore, considering the measurement noise, the low-order parameter models of this method are more favorable than that the high-order parameter models.

Low Energy Less Area Less Delay Fixed Point LMS Method for Adaptive Noise Cancellation Filter

Present paper is about the high speed low complexity implementation derived by its architecture using least mean square (LMS) adaptive filtering. Here straight form LMS adaptive filter has almost the similar critical path as it is a reverse from of the counter path hoiver it has a fast coverage and also a loir register complication. Here critical path evaluation tells that no pipelining is necessary for implementation of straight form LMS adaptive filtering in most of the practical cases requires a realized extremely small adaptive delay and very high sampling rate. Here based on these finding LMS adaptive filtering is divided into 3 structural proposal designs. a) There is no adaption delay b) Only one adaption delay c) Only two adaption delay. Here first one includes least area and least energy per sample (EPS).

Physiologic heart rate dependency of the PQ interval and its sex differences

On standard electrocardiogram (ECG) PQ interval is known to be moderately heart rate dependent, but no physiologic details of this dependency have been established. At the same time, PQ dynamics is a clear candidate for non-invasive assessment of atrial abnormalities including the risk of atrial fibrillation. We studied PQ heart rate dependency in 599 healthy subjects (aged 33.5 ± 9.3 years, 288 females) in whom drug-free day-time 12-lead ECG Holters were available. Of these, 752,517 ECG samples were selected (1256 ± 244 per subject) to measure PQ and QT intervals and P wave durations. For each measured ECG sample, 5-minute history of preceding cardiac cycles was also obtained. Although less rate dependent than the QT intervals (36 ± 19% of linear slopes), PQ intervals were found to be dependent on underlying cycle length in a highly curvilinear fashion with the dependency significantly more curved in females compared to males. The PQ interval also responded to the heart rate changes with a delay which was highly sex dependent (95% adaptation in females and males after 114.9 ± 81.1 vs 65.4 ± 64.3 seconds, respectively, p < 0.00001). P wave duration was even less rate dependent than the PQ interval (9 ± 10% of linear QT/RR slopes). Rate corrected P wave duration was marginally but significantly shorter in females than in males (106.8 ± 8.4 vs 110.2 ± 7.9 ms, p < 0.00001). In addition to establishing physiologic standards, the study suggests that the curvatures and adaptation delay of the PQ/cycle-length dependency should be included in future non-invasive studies of atrial depolarizations.

The contributions of fetal growth restriction and gestational age to developmental outcomes at 12 months of age: A cohort study

BackgroundPreterm birth is a known risk factor for infant development but it is less clear whether fetal growth restriction (FGR) and early term birth between 37 and 39 weeks gestation are associated with risks for infant development. AimsThis study investigated risk factors for adverse developmental outcomes at 12 months of age in a population-based birth cohort. Study designCohort study. SubjectsParticipants in the Raine Study, which recruited 2900 women at 18 weeks of gestation (Gen1) and followed up infants longitudinally (Gen2). At 12 months, 1773 mothers provided developmental data for their infants. Outcome measureThe Ages and Stages Questionnaire (ASQ) was used to measure gross and fine motor, communication, adaptability and personal social development. Multivariate logistic regression analyses were used to estimate associations between FGR, gestational age, sex, breast feeding, parental age, socioeconomic factors and developmental delay at 12 months of age as measured with the ASQ. ResultsThe risk of any delay at 12 months of age, as well as gross motor, fine motor and adaptive delay, was slightly increased for infants born FGR. Preterm and early term birth and male sex were associated with poorer development at 12 months. Breast feeding was protective of developmental status. ConclusionsDevelopmental assessment using the ASQ of infants with FGR was mostly comparable to those born without FGR at 12 months, although finer-grained neurobehavioural assessments may yield capacity for earlier identification of developmental risk. Our data provide weight to the argument that surveillance of early term infants could enable earlier intervention for children at risk.

A novel beaconless routing algorithm based on EBGR algorithm for wireless sensor networks

The purpose of energy-efficient beaconless geographic routing (EBGR) algorithm is to reduce power consumption in the network. But it cannot select the best relay node in all conditions. Also, in the EBGR algorithm, the relay nodes send their data after receiving them, which creates an overhead in the network and decrease spectral efficiency in the network. We introduce an improved method to improve the performance of the EBGR algorithm. In our proposed method, we have divided the space into several subspaces. Each node prioritises the data transmission to the node that is located beneath its own space and along the source-to-destination direction. In order to reduce the slag on the grid, we have also considered adaptive delay. The advantage of this method is that if the network is ideal, the data arrives with the least delay and if the network has a lot of overhead, the delay rate will also increase.

A novel beaconless routing algorithm based on EBGR algorithm for wireless sensor networks

The purpose of energy-efficient beaconless geographic routing (EBGR) algorithm is to reduce power consumption in the network. But it cannot select the best relay node in all conditions. Also, in the EBGR algorithm, the relay nodes send their data after receiving them, which creates an overhead in the network and decrease spectral efficiency in the network. We introduce an improved method to improve the performance of the EBGR algorithm. In our proposed method, we have divided the space into several subspaces. Each node prioritises the data transmission to the node that is located beneath its own space and along the source-to-destination direction. In order to reduce the slag on the grid, we have also considered adaptive delay. The advantage of this method is that if the network is ideal, the data arrives with the least delay and if the network has a lot of overhead, the delay rate will also increase.

Adaptive Control of a Piezo-Positioning Mechanism With Hysteresis and Input Saturation Using Time Delay Estimation

In this paper, based on backstepping technique and time delay estimation (TDE) technique, an adaptive time delay compensation control scheme is developed for a class of piezoelectric positioning mechanical systems with Bouc-Wen hysteresis and input saturation constraint. The nonlinear part of the Bouc-Wen model is estimated online by TDE, and the TDE error introduced by TDE is compensated online by an adaptive law. Furthermore, an auxiliary variable system is used to deal with the input saturation constraint. Based on the Lyapunov method, the stability of the closed-loop system is analyzed and proved. Two simulation examples are given to demonstrate the effectiveness of the proposed control scheme.

A synchronous driving approach based on adaptive delay phase-locked loop for stitching CMOS image sensor

A synchronous driving approach based on adaptive delay phase-locked loop for stitching CMOS image sensor

Adaptive delay optimization of multicast-enabled coded caching in device-to-device networks

This letter investigates a delay optimization problem in device-to-device (D2D) networks where users have pre-downloaded subfiles following a coded caching rule. Due to acquiring rest subfiles, users may suffer both receiving and transmitting delays. To achieve the delay minimization, we first propose a delay-aware mode-selection strategy to adaptively choose multicast or D2D communications mode to reduce the receiving-caused delay. By matching these transmit modes with distinct subfile sizes, we further formulate a min-max optimization problem to minimize the delivery delay. Finally, numerical results prove that the proposed scheme outperforms existing ones in terms of both receiving and transmitting delays.

A 1–10-MHz Frequency-Aware CMOS Active Rectifier With Dual-Loop Adaptive Delay Compensation and &gt;230-mW Output Power for Capacitively Powered Biomedical Implants

This article presents a novel CMOS active rectifier for the emerging modality of capacitive wireless power transfer to biomedical implants with high power budgets. For operation versatility in terms of the input frequency, output power level, input voltage range, and load value, dual-loop adaptive delay compensation is utilized to provide both high resolution and high dynamic range in switched-offset currents of comparators that can be reconfigured for low- and high-speed operation modes for automatic adaptation to the input frequency. Fabricated in 0.18 $\mu \text{m}$ 1P/6M CMOS, the rectifier features power conversion efficiency (PCE) of >84.4% (peak of 91.5%) and voltage conversion ratio (VCR) of >88.6% (peak of 95.1%) when operating in 1–10 MHz and driving a load of 300 $\Omega $ . Moreover, for a load range of 20 $\Omega $ –1 $\text{k}\Omega $ at 5 MHz, PCE of 81%–91.8% and VCR of 78.4%–95.4% are achieved, with a maximum output power of ~232 mW at 50 $\Omega $ with a PCE of 90.1%. The active rectifier is also interfaced with a series-resonant capacitive link formed with coated flexible copper plates around a 3-mm-thick layer of muscle tissue, demonstrating an end-to-end power transfer efficiency of >40% in 2–10 MHz and with a load of 300 $\Omega $ .

Compliance with sedation analgesia protocols: Do clinical pharmacists have an impact?

The agreement between prescribed sedation objectives and sedation pump syringe rate adaptation is not optimal. Delays in adjustment of sedation doses are associated with an increased patient length of stay in the intensive care unit. Our objectives were to assess compliance with the approved sedation protocol and to evaluate the impact of a clinical pharmacist daily controlling sedation and analgesia scores and pump syringe rates on patients' outcomes in a critical care unit. Prospective before/after study involving 60 adult patients divided into two groups (non-intervention and intervention groups) who received mechanical ventilation and continuous infusions of sedative and analgesic drugs in an intensive care unit. In both groups, data were collected daily in 30 mechanically ventilated patients receiving a sedation/analgesia regimen during a 3-month period according to a standardized protocol. A pharmacist was in charge of intervening with physicians when the local sedation analgesia protocol was not followed. There were no significant differences between the groups in terms of demographic characteristics except a higher proportion of men in the intervention group (70% vs 40%, P=.019). In the control group, sedation and analgesia objectives were not prescribed in more than half the cases. Pharmacist intervention reduced sedation duration (5 [2-11] vs 2 [1-5.5]days, P=.019). The cumulative delay in adaptation of the sedation analgesia electric syringe pump was significantly decreased in the intervention group (8 [0-29.5] vs 28.5hours [11.1-68.4], P=.034). Total doses of sedatives (midazolam, propofol) and analgesics (sufentanil, remifentanil) per patient were decreased in the intervention group compared to the control group (respectively, P=.24, P=.0009, P=.0013 and P=.0007). Pharmacist intervention can decrease the sedation duration and the total dose of sedation medications and reinforce adherence to sedation/analgesia guidelines.

A Novel Time-Shared and LUT-Less Pipelined Architecture for LMS Adaptive Filter

This article presents a novel time-shared and lookup table (LUT)-less pipelined architecture for a least-mean-square (LMS) adaptive filter (ADF). The proposed approach first employs a time-shared architecture for the pipelined LMS ADF to compute each filter partial product and coefficient increment term using a single multiplier. Critical path analysis of this architecture is carried out to determine the pipeline requirements. Next, a novel LUT-less multiplier is suggested by exploiting the symmetries between the odd-multiples. Due to the symmetries between the odd-multiples, offset terms are added using an adder tree. For higher wordlength coefficients, only a few adders are required to generate the odd-multiples, and only one offset adder tree is required. Finally, a novel super-latch is developed to pipeline the LUT-less multiplier with adaptation delays of the pipelined LMS ADF. From the implementation results, it is found that the proposed design for the 32nd-order filter occupies 60.32% less area, consumes 61.93% less power, and utilizes 58.83% less sliced LUTs and 63.28% fewer flip-flops over the best existing design.

Will Adaptation Delay the Transition to Clean Energy Systems? An Analysis with AD-MERGE

Climate change is one of the greatest environmental challenges facing our planet in the foreseeable future, yet, despite international environmental agreements, global GHG emissions are still increasing. In this context, adaptation measures can play an important role in reducing climate impacts. These measures involve adjustments to economic or social structures to limit the impact of climate change without limiting climate change itself. To assess the interplay of adaptation and mitigation, we develop AD-MERGE, an integrated assessment model that includes both reactive (‘flow’) and proactive (‘stock’) adaptation strategies as well as a range of mitigation (energy) technologies. We find that applying adaptation optimally delays but does not prevent the transition to clean energy systems (carbon capture and sequestration systems, nuclear, and renewables). Moreover, applying both adaptation and mitigation is more effective than using just one.

A 13.56 MHz, 94.1% Peak Efficiency CMOS Active Rectifier With Adaptive Delay Time Control for Wireless Power Transmission Systems

In this paper, an adaptive delay time control (ADTC)-based CMOS active rectifier is proposed. Compared with previous active rectifiers, power-hungry comparators are eliminated in this structure. Instead, optimal on/off time of the power switches is generated by two current controlled delay lines (CCDLs), which enables drastic power reduction of the active rectifier. In addition, the multiple-pulsing problem is eliminated due to the introduced control mechanism. The high-precision on/off control at picosecond-level precision removes the reverse current of the rectifier and guarantees high voltage conversion rate (VCR) and power conversion efficiency (PCE). The active rectifier is fabricated with a standard 0.18- $\mu \text{m}$ CMOS process. The experimental results show that the quiescent power consumption of the rectifier is less than 230 $\mu \text{W}$ . The current conduction angle reaches the optimal state under different input and load conditions because of the adaptive adjustment. The peak PCE is 94.1% at the output power of 10.63 mW. The PCE is enhanced by 6.7% compared with the previous design. The maximum output power of 34.1 mW is achieved with input ac amplitude of 2.5 V. The proposed low-power high-efficiency active rectifier gives a favorable solution for the wireless power transmission systems.

Diagnostic accuracy of a novel predictive model for ischemic events based on small dense LDL-cholesterol concentration (SDLDL-C) and lipid characterization by NMR

Proper adaptation of ventricular repolarization (VR) to rapid heart rate (HR) increase is crucial for cardiac electro-mechanical function. The pattern and temporal aspects of this adaptation and its components (duration and dispersion) during normal conduction are, however, incompletely known in humans and were the topic of this study.The VR duration (QT & QTpeak) and dispersion (Tamplitude, Tarea & ventricular gradient; VG) responses were studied by continuous vectorcardiogram after a bolus injection of atropine 0.04 mg/kg b.w. in 31 healthy young adults (16 men). The primary measure (T90 End) was the time to reach 90% change from baseline to end value 300 s later.Mean (SD) of T90 End was 23 (9) s for a 41% RR decrease, 130 (35) s for a 16% QTend decrease and 110 (36) s for a 19% QTpeak decrease; the response was single-exponential for these measures. For 35–43% decreases of Tamplitude, Tarea & VG, mean (SD) of T90 End were 21 (10), 38 (20) and 40 (23) s and the response pattern was double-exponential with varying overshoot.VR duration and dispersion responses to a very rapid HR increase during normal conduction differed substantially. In contrast to the well-known single-exponential delay in VR duration adaptation the responses of VR dispersion measures were double-exponential and much more rapid. We describe a new and completely non-invasive phenotypic characterization of different components of VR adaptation.