Asynchronous Running Research Articles

Comparison of Concurrent and Asynchronous Running Kinematics and Kinetics From Marker-Based and Markerless Motion Capture Under Varying Clothing Conditions.

As markerless motion capture is increasingly used to measure 3-dimensional human pose, it is important to understand how markerless results can be interpreted alongside historical marker-based data and how they are impacted by clothing. We compared concurrent running kinematics and kinetics between marker-based and markerless motion capture, and between 2 markerless clothing conditions. Thirty adults ran on an instrumented treadmill wearing motion capture clothing while concurrent marker-based and markerless data were recorded, and ran a second time wearing athletic clothing (shorts and t-shirt) while markerless data were recorded. Differences calculated between the concurrent signals from both systems, and also between each participant's mean signals from both asynchronous clothing conditions were summarized across all participants using root mean square differences. Most kinematic and kinetic signals were visually consistent between systems and markerless clothing conditions. Between systems, joint center positions differed by 3cm or less, sagittal plane joint angles differed by 5° or less, and frontal and transverse plane angles differed by 5° to 10°. Joint moments differed by 0.3N·m/kg or less between systems. Differences were sensitive to segment coordinate system definitions, highlighting the effects of these definitions when comparing against historical data or other motion capture modalities.

Implementation of Asynchronous Distributed Gauss-Newton Optimization Algorithms for Uncertainty Quantification by Conditioning to Production Data

Summary Previous implementation of the distributed Gauss-Newton (DGN) optimization algorithm ran multiple optimization threads in parallel, employing a synchronous running mode (S-DGN). As a result, it waits for all simulations submitted in each iteration to complete, which may significantly degrade performance because a few simulations may run much longer than others, especially for time-consuming real-field cases. To overcome this limitation and thus improve the DGN optimizer’s execution, we propose two asynchronous DGN (A-DGN) optimization algorithms in this paper. The two A-DGN optimization algorithms are (1) the local-search algorithm (A-DGN-LS) to locate multiple maximum a-posteriori (MAP) estimates and (2) the integrated global-search algorithm with the randomized maximum likelihood (RML) method (A-DGN + RML) to generate hundreds of RML samples in parallel for uncertainty quantification. We propose using batch together with a checking time interval to control the optimization process. The A-DGN optimizers check the status of all running simulations after every checking time frame. The iteration index of each optimization thread is updated dynamically according to its simulation status. Thus, different optimization threads may have different iteration indices in the same batch. A new simulation case is proposed immediately once the simulation of an optimization thread is completed, without waiting for the completion of other simulations. We modified the training data set updating algorithm using each thread’s dynamically updated iteration index to implement the asynchronous running mode. We apply the modified QR decomposition method to estimate the sensitivity matrix at the best solution of each optimization thread by linear interpolation of all or a subset of the training data to avoid the issue of solving a linear system with a singular matrix because of insufficient training data points in early batches. A new simulation case (or search point) is generated by solving the Gauss-Newton (GN) trust-region subproblem (GNTRS) using the estimated sensitivity matrix. We developed a more efficient and robust GNTRS solver using eigenvalue decomposition (EVD). The proposed A-DGN optimization methods are tested and validated on a 2D analytical toy problem and a synthetic history-matching problem and then applied to a real-field deepwater reservoir model. Numerical tests confirm that the proposed A-DGN optimization methods can converge to solutions with matching quality comparable to those obtained by the S-DGN optimizers, saving on the time required for the optimizer to converge by a factor ranging from 1.3 to 2 when compared to the S-DGN optimizer depending on the problem. The new A-DGN optimization algorithms improve efficiency and robustness in solving history-matching or inversion problems, especially for uncertainty quantification of subsurface model parameters and production forecasts of real-field reservoirs by conditioning production data.

Sampled-point-based partition control of linear switched systems with a novel asynchronous switching rule

This paper investigates the aperiodic sampling stabilisation problem for a class of switched linear systems under asynchronous switching. Based on a novel dynamic sampling rule, a sampling-point-based partition-dependent discontinuous Lyapunov functions control approach are developed to make the considered closed-loop switched systems be globally asymptotically stable. Compared with the existing results, the proposed control method permits frequent switching in a sampling interval for subsystems. But the frequent information transmission to the matched controllers and the negative effect of long asynchronous running on system performance can be nicely handled in this paper. Moreover, the partitioned Lyapunov functions are allowed to increase in some segments of the synchronous operating intervals. Tighter synchronous duration and switching number which are determined by more than affine functions make the switching signal more flexible. Finally, simulation analyses of two examples show the advantages of the developed control strategy.

Musical information increases physical performance for synchronous but not asynchronous running

Given that physical performance is enhanced by listening to music, what information in the music is the active ingredient? Here, we varied the amount of music information in an otherwise identical piece of music, from only the rhythm, through a synthesized and scaled down version, to the full original version. Twenty-two university students (11 males and 11 females) ran for 10 minutes to each of eight conditions, two with white noise, three with music that facilitated synchronization with the running pace, and three with tempi where synchronization was impossible. Dependent variables were distance run and the number of steps, from which stride length was computed. Heart rate and mood (PANAS) were also measured for control purposes. Participants tended to run a greater distance when there was more music information, which was mainly an effect of longer strides rather than a faster stride rate. This effect was stronger in the synchronous conditions. The results suggest that the motivational effects of music information during running is mostly related to richer temporal information conveyed by faster metrical levels, when attempting to synchronize with the beat in the music

ALAR-Ts automatic facility for liquidation of asynchronous operating conditions

The operating principle and main performance characteristics of a digital device ALAR-Ts for automatic liquidation of asynchronous running are considered. The device is based on a new approach to determining asynchronous operation in its initial phase before the angle δ between the electromotive forces of the equivalent generators of two parts of a dividing power system attains 180° and does not require prescription of any setting dependent on the composition and operating conditions of the power system. Oscillograms of transient processes are presented, which illustrate the operation of the device.

A Method for Automatic Suppression of Asynchronism

Variation of electrical quantities, in particular, of the voltage and current frequencies, detected in the Armenian Power System in the process of appearance and occurrence of asynchronous operating conditions, which was superimposed on an extended fault, confirms the known laws of the theory of asynchronous running. The voltage frequency varies in the asynchronous mode by a nonlinear dependence having a well-manifested peak that increases as the electrical angle a approaches 180° and the electric swing center (ESC) approaches the point of measurement. The mean frequency of rotation of the current vector in a line per period of asynchronous running is equal to the mean frequency of rotation of the voltage vector at the higher-voltage end of the line. At the other end of the line the difference in the mean values of the voltage and current frequencies in the line is equal to the mean value of slip of the asynchronous running. The phases of variation of the voltage frequency at the opposite ends of the line with ESC are opposite; at the opposite ends of adjacent lines these phases are similar. These features are used for creating guides for automatic suppression of asynchronous running (ASA).

Application of higher‐order spectra for signal processing in electrical power engineering

During recent years, higher order statistics (HOS) have found a wide applicability in many diverse fields, e.g. biomedicine, harmonic retrieval and adaptive filtering. In power spectrum estimation, the signal under consideration is processed in such a way that the distribution of power among its frequency is estimated and phase relations between the frequency components are suppressed. Higher order statistics and their associated Fourier transforms reveal not only amplitude information about a signal, but also phase information. If a non‐Gaussian signal is received along with additive Gaussian noise, a transformation to higher order cumulant domain eliminates the noise. These are some methods for estimation of signal components, based on HOS. In the paper we apply the MUSIC method both for the correlation and the fourth order cumulant, to investigate the state of asynchronous running of synchronous machines and the fault operation of inverter‐fed induction motors. When the investigated signal is distorted by a coloured noise, more exact results can be achieved by applying cumulants.

Effects of slots on eddy currents in solid iron rotors

The presence of slots in the solid rotors of asynchronously running turboalternators is shown to have a significant influence on the eddy-current distribution in the rotor. The theory presented in a previous paper is extended to cover the effects of the rotor slots, and agreement with torque values observed with a model machine and with a large turboalternator is obtained. The theoretical results are also utilised to predict the behaviour of the model machine when it is resynchronised from a condition of steady asynchronous running.