Asynchronous Integration Research Articles

Delocalized, asynchronous, closed-loop discovery of organic laser emitters.

Contemporary materials discovery requires intricate sequences of synthesis, formulation, and characterization that often span multiple locations with specialized expertise or instrumentation. To accelerate these workflows, we present a cloud-based strategy that enabled delocalized and asynchronous design-make-test-analyze cycles. We showcased this approach through the exploration of molecular gain materials for organic solid-state lasers as a frontier application in molecular optoelectronics. Distributed robotic synthesis and in-line property characterization, orchestrated by a cloud-based artificial intelligence experiment planner, resulted in the discovery of 21 new state-of-the-art materials. Gram-scale synthesis ultimately allowed for the verification of best-in-class stimulated emission in a thin-film device. Demonstrating the asynchronous integration of five laboratories across the globe, this workflow provides a blueprint for delocalizing-and democratizing-scientific discovery.

Energy-conserving interface dynamics with asynchronous direct time integration employing arbitrary time steps

The derivation and implementation of an asynchronous direct time integration scheme for domain-decomposed finite element models is presented. To maximize clarity in the description of the proposed asynchronous integration, the scheme is restricted to the linear-elastic stress wave propagation case. The proposed method allows the integration of individual subdomains with independent time steps. There is no requirement for an integer time steps ratio of the interacting domains while maintaining zero interface energy. The subdomains are connected by the condition of the continuity of the acceleration field at the interface. In addition, the a posteriori technique is applied to satisfy the continuity of the displacement and velocity fields. Another important contribution of this paper lies in the description of the implementation — we offer the reader a general description of the implementation of the case of any number of subdomains with any number of constraints between them, while the basics of the algorithm are explained on a single domain pair. The functionality of the asynchronous integrator is verified by solving selected problems and comparing with analytical solutions and experimental measurements obtained using a Split Hopkinson pressure bar setup.

Direct Observation of Oxygen Ion Dynamics in a WO3‐x based Second‐Order Memristor with Dendritic Integration Functions

AbstractDirect observation of oxygen dynamics in an oxide‐based second‐order memristor can provide the valid evidence to clarify the memristive mechanism, however, which is still limited for now. In this study, the migration and diffusion of oxygen ions in the region of Pt/WO3‐x Schottky interface are observed in the WO3‐x second‐order memristor by using the technique of in situ transmission electron microscopy (TEM) and the electron energy loss spectroscopy. Interestingly, the coexistence of memristive and memcapacitive switching can be implemented in this memristor. Combined with the analysis of depth‐profile X‐ray photoelectron spectroscopy (XPS), an interface‐barrier‐modulation second‐order memristive model is proposed based on the above results. Notably, temporally correlative oxygen dynamics in the memristor offers the platform to integrate signals from multiple inputs, enabling the realization of the dendritic functions of synchronous and asynchronous integration for the application of logic operations with fault‐tolerance capability and associative learning. These findings provide the experimental evidence to in‐depth understanding of oxygen dynamics and switching mechanism in second‐order memristor, which can support the optimization of memristive performance and the achievement of biorealistic synaptic functions.

The influence of the cross-modal emotional pre-preparation effect on audiovisual integration.

Previous studies have shown that the cross-modal pre-preparation effect is an important factor for audiovisual integration. However, the facilitating influence of the pre-preparation effect on the integration of emotional cues remains unclear. Therefore, this study examined the emotional pre-preparation effect during the multistage process of audiovisual integration. Event-related potentials (ERPs) were recorded while participants performed a synchronous or asynchronous integration task with fearful or neutral stimuli. The results indicated that, compared with the sum of the unisensory presentation of visual (V) and auditory (A) stimuli (A+V), only fearful audiovisual stimuli induced a decreased N1 and an enhanced P2; this was not found for the neutral stimuli. Moreover, the fearful stimuli triggered a larger P2 than the neutral stimuli in the audiovisual condition, but not in the sum of the combined (A+V) waveforms. Our findings imply that, in the early perceptual processing stage and perceptual fine processing stage, fear improves the processing efficiency of the emotional audiovisual integration. In the last cognitively assessing stage, the fearful audiovisual induced a larger late positive component (LPC) than the neutral audiovisual. Moreover, the asynchronous-audiovisual induced a greater LPC than the synchronous-audiovisual during the 400-550 ms period. The different integration effects between the fearful and neutral stimuli may reflect the existence of distinct mechanisms of the pre-preparation in terms of the emotional dimension. In light of these results, we present a cross-modal emotional pre-preparation effect involving a three-phase emotional audiovisual integration.

An asynchronous integration method for accelerated finite element analysis

Elasto-plastic boundary value problems involving heterogeneous geometry, material properties and/or loading can have localized deformation, stress, and, plastic flow. The Finite Element Method (FEM) finds wide spread usage to solve such boundary value problems. However due to localized deformation, the speed of FEM simulation can be extremely slow owing to the need of small time steps to ensure convergence. The difficulty in convergence can arise due to the large spatio-temporal gradient and strong non-linearity in the region of localization. The issue of increased computational time can be alleviated by the use of asynchronous integration wherein different sub-domains are evolved with different time step sizes and synchronization after certain time interval. However, the speedup and accuracy of the solution is strongly influenced by the interface constraint condition, sub-domain selection and the disparity in time step sizes required in the sub-domains. In the present work, an asynchronous integration method is proposed for quasi-static problems with material non-linearity and geometric imperfection. The interfaces between the sub-domains are constrained such that the incremental energy is balanced over the largest time increment. The performance of the method is evaluated for one and two-dimensional boundary value problems with viscoplastic material behavior. In both the cases geometric imperfections are introduced to obtain localization. Different sub-domain sizes and tolerance values are considered to evaluate their impact on accuracy and computational speed up.

A real-time human-robot interaction framework with robust background invariant hand gesture detection

Abstract In the light of factories of the future, to ensure productive and safe interaction between robot and human coworkers, it is imperative that the robot extracts the essential information of the coworker. We address this by designing a reliable framework for real-time safe human-robot collaboration, using static hand gestures and 3D skeleton extraction. OpenPose library is integrated with Microsoft Kinect V2, to obtain a 3D estimation of the human skeleton. With the help of 10 volunteers, we recorded an image dataset of alpha-numeric static hand gestures, taken from the American Sign Language. We named our dataset OpenSign and released it to the community for benchmarking. Inception V3 convolutional neural network is adapted and trained to detect the hand gestures. To augment the data for training the hand gesture detector, we use OpenPose to localize the hands in the dataset images and segment the backgrounds of hand images, by exploiting the Kinect V2 depth map. Then, the backgrounds are substituted with random patterns and indoor architecture templates. Fine-tuning of Inception V3 is performed in three phases, to achieve validation accuracy of 99.1% and test accuracy of 98.9%. An asynchronous integration of image acquisition and hand gesture detection is performed to ensure real-time detection of hand gestures. Finally, the proposed framework is integrated in our physical human-robot interaction library OpenPHRI. This integration complements OpenPHRI by providing successful implementation of the ISO/TS 15066 safety standards for “safety rated monitored stop” and “speed and separation monitoring” collaborative modes. We validate the performance of the proposed framework through a complete teaching by demonstration experiment with a robotic manipulator.

Study on Control Strategy of Hydropower Asynchronous Integration Coupling with DC Emergency Power Support

The hydropower group is a kind of weak AC system while hydropower asynchronous interconnected with main network through VSC-HVDC (Voltage Source Converter based High Voltage Direct Current). Thus, VSC-HVDC should be taken part into the system voltage and frequency control, which can enhance the transient stability of power grid while reduce the conventional control costs at the same time. The transfer function of turbine governor is introduced to expound the principle of hydraulic turbine unit participating in DC power support. Different kinds of DC power modulation have been compared which show the difference of power angle recovery after fault between VSC-HVDC and LCC-HVDC (Line Commutated Converter based High Voltage Direct Current) power support, thus the modulation priority of different kinds of DC in the emergency control should be taken into consideration. The DC power support quantity calculation method after fault is proposed in this paper. The emergency coordination control strategy can be formulated by considering with both priority and DC power support quantity under different fault.

Traffic Multiresolution Modeling and Consistency Analysis of Urban Expressway Based on Asynchronous Integration Strategy

The paper studies multiresolution traffic flow simulation model of urban expressway. Firstly, compared with two-level hybrid model, three-level multiresolution hybrid model has been chosen. Then, multiresolution simulation framework and integration strategies are introduced. Thirdly, the paper proposes an urban expressway multiresolution traffic simulation model by asynchronous integration strategy based on Set Theory, which includes three submodels: macromodel, mesomodel, and micromodel. After that, the applicable conditions and derivation process of the three submodels are discussed in detail. In addition, in order to simulate and evaluate the multiresolution model, “simple simulation scenario” of North-South Elevated Expressway in Shanghai has been established. The simulation results showed the following.(1)Volume-density relationships of three submodels are unanimous with detector data.(2)When traffic density is high, macromodel has a high precision and smaller error and the dispersion of results is smaller. Compared with macromodel, simulation accuracies of micromodel and mesomodel are lower but errors are bigger.(3)Multiresolution model can simulate characteristics of traffic flow, capture traffic wave, and keep the consistency of traffic state transition. Finally, the results showed that the novel multiresolution model can have higher simulation accuracy and it is feasible and effective in the real traffic simulation scenario.

Active fantasy sports: rationale and feasibility of leveraging online fantasy sports to promote physical activity.

BackgroundThe popularity of active video games (AVGs) has skyrocketed over the last decade. However, research suggests that the most popular AVGs, which rely on synchronous integration between players’ activity and game features, fail to promote physical activity outside of the game or for extended periods of engagement. This limitation has led researchers to consider AVGs that involve asynchronous integration of players’ ongoing physical activity with game features. Rather than build an AVG de novo, we selected an established sedentary video game uniquely well suited for the incorporation of asynchronous activity: online fantasy sports.ObjectiveThe primary aim of this study was to explore the feasibility of a new asynchronous AVG—active fantasy sports—designed to promote physical activity.MethodsWe conducted two pilot studies of an active fantasy sports game designed to promote physical activity. Participants wore a low cost triaxial accelerometer and participated in an online fantasy baseball (Study 1, n=9, 13-weeks) or fantasy basketball (Study 2, n=10, 17-weeks) league. Privileges within the game were made contingent on meeting weekly physical activity goals (eg, averaging 10,000 steps/day).ResultsAcross the two studies, the feasibility of integrating physical activity contingent features and privileges into online fantasy sports games was supported. Participants found the active fantasy sports game enjoyable, as or more enjoyable than traditional (sedentary) online fantasy sports (Study 1: t 8=4.43, P<.01; Study 2: t 9=2.09, P=.07). Participants in Study 1 increased their average steps/day, t 8=2.63, P<.05, while participants in Study 2 maintained (ie, did not change) their activity, t 9=1.57, P=.15). In postassessment interviews, social support within the game was cited as a key motivating factor for increasing physical activity.ConclusionsPreliminary evidence supports potential for the active fantasy sports system as a sustainable and scalable intervention for promoting adult physical activity.

An asynchronous solver for systems of ODEs linked by a directed tree structure

This paper documents our development and evaluation of a numerical solver for systems of sparsely linked ordinary differential equations in which the connectivity between equations is determined by a directed tree. These types of systems arise in distributed hydrological models. The numerical solver is based on dense output Runge–Kutta methods that allow for asynchronous integration. A partition of the system is used to distribute the workload among different processes, enabling a parallel implementation that capitalizes on a distributed memory system. Communication between processes is performed asynchronously. We illustrate the solver capabilities by integrating flow transport equations for a ∼17,000km2 river basin subdivided into 305,000 sub-watersheds that are interconnected by the river network. Numerical experiments for a few models are performed and the runtimes and scalability on our parallel computer are presented. Efficient numerical integrators such as the one demonstrated here bring closer to reality the goal of implementing fully distributed real-time flood forecasting systems supported by physics based hydrological models and high-quality/high-resolution rainfall products.

Toward high-quality modal contact sound

Contact sound models based on linear modal analysis are commonly used with rigid body dynamics. Unfortunately, treating vibrating objects as "rigid" during collision and contact processing fundamentally limits the range of sounds that can be computed, and contact solvers for rigid body animation can be ill-suited for modal contact sound synthesis, producing various sound artifacts. In this paper, we resolve modal vibrations in both collision and frictional contact processing stages, thereby enabling non-rigid sound phenomena such as micro-collisions, vibrational energy exchange, and chattering. We propose a frictional multibody contact formulation and modified Staggered Projections solver which is well-suited to sound rendering and avoids noise artifacts associated with spatial and temporal contact-force fluctuations which plague prior methods. To enable practical animation and sound synthesis of numerous bodies with many coupled modes, we propose a novel asynchronous integrator with model-level adaptivity built into the frictional contact solver. Vibrational contact damping is modeled to approximate contact-dependent sound dissipation. Results are provided that demonstrate high-quality contact resolution with sound.

Asynchronous multi-domain variational integrators for nonlinear hyperelastic solids

We present the asynchronous multi-domain variational time integrators with a dual domain decomposition method for the initial hyperbolic boundary-value problem in hyperelasticity. Variational time integration schemes, based on the principle of minimal action within the Lagrangian framework, are constructed for the equation of motion and implemented into a variational finite element framework, which is systematically derived from the three-field de Veubeke-Hu-Washizu variational principle to accommodate the incompressibility constraint present in an analysis of nearly-incompressible materials. For efficient parallel computing, we use the dual domain decomposition method with local Lagrange multipliers to ensure the continuity of the displacement field at the interface between subdomains. The α-method for time discretization and the multi-domain spatial decomposition enable us to use different types of integrators (explicit vs. implicit) and different time steps on different parts of a computational domain, and thus efficiently capture the underlying physics with less computational effort. The energy conservation of our nonlinear, midpoint, asynchronous integration scheme is investigated using the Energy method, and both local and the global energy error estimates are derived. We illustrate the performance of proposed variational multi-domain time integrators by means of three examples. First, the method of manufactured solutions is used to examine the consistency of the formulation. In the second example, we investigate energy conservation and stability. Finally, we apply the method to the motion of a heterogeneous plane domain, where different integrators and time discretization steps are used accordingly with disparate material data of individual parts.

Sarmatia-Volgo-Uralia junction zone: Isotopic-geochronologic characteristic of supracrustal rocks and granitoids

The geochronologic (U-Pb isotopic system of zircons) and isotopic-geochemical (Sm-Nd isotopic system of the bulk rock) studies were performed along the profile extending from the eastern Sarmatia (in the west) to the Middle Volga megablock of Volgo-Uralia (in the east), i.e., across the entire junction zone for dating the integration of Sarmatia and Volgo-Uralia, representing two segments of the East European Craton. It is established that the examined rocks are characterized by the Paleoproterozoic Nd isotopic model age, which varies from 2.1 and 2.4 Ga, except for some samples indicating a similar age of the crust through the entire Sarmatia-Volgo-Uralia junction zone. The highly metamorphosed complexes of the granulite and amphibolite facies constituting the southwestern margin of Volgo-Uralia are Paleoproterozoic, not Archean, in age, contrary to previous views. Two Early Paleoproterozoic lithotectonic complexes are defined in Volgo-Uralia: South Volga metasedimentary and Tersa metasedimentary-volcanogenic. The obtained data confirm the asynchronous integration of individual segments into the East European Craton: the integration of Sarmatia and Volgo-Uralia approximately 2100-2000 Ma ago was followed by the conjunction of this newly-formed continent with Fennoscandia ca. 1800 Ma ago.

The Asynchronous Integration of Digital Resources in Different Systems Based on AJAX

The Asynchronous Integration of Digital Resources in Different Systems Based on AJAX

Multi-scale gas discharge simulations using asynchronous adaptive mesh refinement

The breakdown of a gas gap at high products of pd (pressure × distance) is a multi-scale phenomenon in both time and space. This is especially true when the plasma is interacting with a gas flow, a problem of considerable recent interest in the context of aerodynamic applications of surface discharges. This paper presents a contribution to the numerical modeling of such discharges. We describe here a new approach for adaptive meshing which is suitable for use with the explicit asynchronous integration scheme described in our previous publication. Rather than relying on a family of nested grids as is commonly done, this technique is based on a single unstructured mesh with possible non-conforming cells at the interface between coarse and fine areas. Substantial computational time saving has been achieved for a surface dielectric barrier discharge configuration of the kind proposed as plasma actuators for flow control.

Asynchronous multi‐domain variational integrators for non‐linear problems

AbstractWe develop an asynchronous time integration and coupling method with domain decomposition for linear and non‐linear problems in mechanics. To ensure stability in the time integration and in coupling between domains, we use variational integrators with local Lagrange multipliers to enforce continuity at the domain interfaces. The asynchronous integrator lets each domain step with its own time step, using a smaller time step where required by stability and accuracy constraints and a larger time step where allowed. We show that in practice the time step is limited by accuracy requirements rather than by stability requirements. Copyright © 2008 John Wiley &amp; Sons, Ltd.

Asynchronous neural integration: Compensation or computational tolerance and skill acquisition?

AbstractNijhawan argues that neural compensation is necessary to account for couplings of perception and action. Although perhaps true in some cases, computational tolerance for asynchronously arriving continuous information is of more importance. Moreover, some of the everyday venues Nijhawan uses to argue for the relevance of prediction and compensation can be better ascribed to skill.

DJIA Index Membership and the Flow of Information Between Stock Returns

We contribute to the limited literature on interactions between individual stocks at the market microstructure level by utilizing an asynchronous multi-asset data integration methodology. For the periods before and after the Dow Jones Industrial Average (DJIA) revisions in 1999 and 2004, we investigate effects of membership in the DJIA on the changes in the relative speed of price adjustment to common information. Although, for the analyzed stocks, index membership in many cases is associated with a higher relative speed of price adjustment, it is neither a necessary nor a sufficient condition for having a lead in price movement.

An asynchronous scheme with local time stepping for multi-scale transport problems: Application to gas discharges

This paper presents an asynchronous integration scheme with local time stepping for transport problems. The concept consists in associating refresh time tags to the interface fluxes between cells and to the source terms within the cells rather than to the cell themselves. This scheme is less diffusive numerically than its synchronous equivalent. This method is very effective in terms of computation time for problems with localized sharp minima in the CFL condition. The method is then applied to dielectric barrier discharges for aerodynamic flow control.

An asynchronous integration and event detection algorithm for simulating multi-agent hybrid systems

A simulation algorithm is presented for multi-agent hybrid systems---systems consisting of many sets of nonsmooth differential equations---such as systems involving multiple rigid bodies, vehicles, or airplanes. The differential equations are partitioned into coupled subsystems, called "agents"; and the conditions which trigger the discontinuities in the derivatives, called "events", may depend on the global state vector. Such systems normally require significant computational resources to simulate because a global time step is used to ensure the discontinuity is properly handled. When the number of systems is large, forcing all system to be simulated at the same rate creates a computational bottleneck, dramatically decreasing efficiency. By using a control systems approach for selecting integration step sizes, we avoid using a global time step. Each subsystem can be simulated asynchronously when the state is away from the event. As the state approaches the event, the simulation is able to synchronize each of the local time clocks in such a way that the discontinuities are properly handled without the need for "roll back". The algorithm's operation and utility is demonstrated on an example problem inspired by autonomous highway vehicles. Using a combination of stochastic modelling and numerical experiments we show that the algorithm requires significantly less computation time when compared with traditional simulation techniques for such problems, and scales more favorably with problem size.