Journal articles: 'Asynchronous Executions'

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HADDIX, F. FURMAN. "AN ORDER DEGREE ALTERNATOR FOR ARBITRARY TOPOLOGIES." Parallel Processing Letters 18, no. 02 (June 2008): 307–22. http://dx.doi.org/10.1142/s0129626408003405.

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An alternator is an arbitrary set of interacting processes that satisfies three conditions. First, if a process executes its critical section, then no neighbor of that process can execute its critical section at the same state. Second, along any infinite sequence of system states, each process will execute its critical section, an infinite number of times. Third, along any maximally concurrent computation, the alternator will stabilize to a sequence of states in which the processes will execute their critical sections in alternation. A principal reason for interest in alternators is their ability to transform systems correct under serial execution semantics to systems that are correct under concurrent execution semantics. An earlier alternator for arbitrary topology required 2q states where q is the dependency graph circumference and after stabilization would wait 2q steps between critical section executions. In a synchronous environment, this alternator requires only 2d+1 states where d is the degree of the graph of process dependencies for the system and after stabilization will require a wait of 2d+1 steps between critical section executions. In an asynchronous environment, the synchronization properties of this alternator must be supplemented with an asynchronous unison algorithm. The asynchronous unison algorithm requires expansion of the required number of states to dt, where t is the longest chordless cycle in the dependency graph; however, the required wait between critical section executions remains O(d).

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ANCEAUME, Emmanuelle. "EFFICIENT SOLUTION TO UNIFORM ATOMIC BROADCAST." International Journal of Foundations of Computer Science 13, no. 05 (October 2002): 695–717. http://dx.doi.org/10.1142/s0129054102001400.

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Chandra and Toueg proposed in 1993 a new approach to overcome the impossibility of reaching deterministically Consensus — and by corollary Atomic Broadcast — in asynchronous systems subject to crash failures. They augment the asynchronous system with a possibly Unreliable Failure Detector which provides some information about the operational state of processes. In this paper, we present an extension of the Consensus problem that we call Uniform Prefix Agreement. This extension enables all the processes to propose a flow of messages during an execution — instead of one as in the Consensus problem — and uses all these proposed messages to compose the decision value. Prefix Agreement is based on an Unreliable Failure Detector. We use repeated executions of Prefix Agreement to build an efficient Uniform Atomic Broadcast algorithm. This paper describes the Uniform Prefix Agreement and Uniform Atomic Broadcast algorithms, and provides proofs of their correctness.

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Raghavan, Hari K., and Sathish S. Vadhiyar. "Efficient asynchronous executions of AMR computations and visualization on a GPU system." Journal of Parallel and Distributed Computing 73, no. 6 (June 2013): 866–75. http://dx.doi.org/10.1016/j.jpdc.2013.03.002.

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Kallas, Konstantinos, Haoran Zhang, Rajeev Alur, Sebastian Angel, and Vincent Liu. "Executing Microservice Applications on Serverless, Correctly." Proceedings of the ACM on Programming Languages 7, POPL (January 9, 2023): 367–95. http://dx.doi.org/10.1145/3571206.

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While serverless platforms substantially simplify the provisioning, configuration, and management of cloud applications, implementing correct services on top of these platforms can present significant challenges to programmers. For example, serverless infrastructures introduce a host of failure modes that are not present in traditional deployments. Individual serverless instances can fail while others continue to make progress, correct but slow instances can be killed by the cloud provider as part of resource management, and providers will often respond to such failures by re-executing requests. For functions with side-effects, these scenarios can create behaviors that are not observable in serverful deployments. In this paper, we propose mu2sls, a framework for implementing microservice applications on serverless using standard Python code with two extra primitives: transactions and asynchronous calls. Our framework orchestrates user-written services to address several challenges, such as failures and re-executions, and provides formal guarantees that the generated serverless implementations are correct. To that end, we present a novel service specification abstraction and formalization of serverless implementations that facilitate reasoning about the correctness of a given application’s serverless implementation. This formalization forms the basis of the mu2sls prototype, which we then use to develop a few real-world microservice applications and show that the performance of the generated serverless implementations achieves significant scalability (3-5× the throughput of a sequential implementation) while providing correctness guarantees in the context of faults, re-execution, and concurrency.

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Kashyap, Amlesh, Sathish S. Vadhiyar, Ravi S. Nanjundiah, and P. N. Vinayachandran. "Asynchronous and synchronous models of executions on Intel® Xeon Phi™ coprocessor systems for high performance of long wave radiation calculations in atmosphere models." Journal of Parallel and Distributed Computing 102 (April 2017): 199–212. http://dx.doi.org/10.1016/j.jpdc.2016.12.018.

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MUSCALAGIU, IONEL, JOSE M. VIDAL, VLADIMIR CRETU, HORIA EMIL POPA, and MANUELA PANOIU. "EXPERIMENTAL ANALYSIS OF THE EFFECTS OF AGENT SYNCHRONIZATION IN ASYNCHRONOUS SEARCH ALGORITHMS." International Journal of Software Engineering and Knowledge Engineering 18, no. 05 (August 2008): 619–36. http://dx.doi.org/10.1142/s0218194008003799.

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The asynchronous searching techniques are characterized by the fact that each agent instantiates its variables in a concurrent way. Then, it sends the values of its variables to other agents directly connected to it by using messages. These asynchronous techniques have different behaviors in the case of delays in sending messages. This article presents the opportunity for synchronizing the execution of agents in the case of asynchronous techniques. It investigates and compares the behaviors of several asynchronous techniques in two cases: agents process the received messages asynchronously (the real situation) and the synchronous case, when a synchronization of the execution of agents is done, i.e. the agents perform a computing cycle in which they process a message from a message queue. After that, the synchronization is done by waiting for the other agents to finalize the processing of their messages. The experiments show that the synchronization of the agents execution leads to lower costs in searching for solutions. A solution for synchronizing the agents execution is suggested for the analyzed asynchronous techniques.

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Krämer, Bernd J., and Thomas Koch. "Distributed Systems Management Software-in-the-Loop." International Journal of Software Engineering and Knowledge Engineering 08, no. 01 (March 1998): 55–76. http://dx.doi.org/10.1142/s0218194098000066.

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IT experts expect open distributed processing to become the predominant computing infrastructure in the late nineties. All computer supported work places of large enterprises and organizations will then be networked and will be integrated into cross-regional and cross-sector business and information processes. The size and complexity of such applications, the local autonomy, distribution and heterogeneity of participating subsystems, and their asynchronous interaction, however, require new architectures, strategies, and tools for their technical management. In previous work we placed a production rule interpreter into the monitoring, decision, control action loop to provide flexible, operational semantics of well-understood management policies. In this article we extend this work in two directions. First we map the structure and dynamic behavior of policies into a graph representation. This semantic representation enables a systematic prediction of the effects of policy executions and allows for a better impact analysis in case of policy changes. Then we introduce a declarative event definition mechanism. It supports a causal and temporal correlation of individual events and serves to instantiate and adapt a predefined generic event handler to the specific needs of the actual management application. Such event handlers join in the interaction between monitoring agents and policy interpreter. By event correlation they may reduce the number of events triggering management actions significantly and help to filter secondary events.

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Gilbert, Martin S., and Ramalingam Sridhar. "AMEC — Asynchronous microprogram execution controller." Microprocessing and Microprogramming 36, no. 1 (November 1992): 9–25. http://dx.doi.org/10.1016/0165-6074(92)90003-p.

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Malloy, B. A., E. L. Lloyd, and M. L. Soffa. "Scheduling DAG's for asynchronous multiprocessor execution." IEEE Transactions on Parallel and Distributed Systems 5, no. 5 (May 1994): 498–508. http://dx.doi.org/10.1109/71.282560.

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Okumura, Keisuke, Yasumasa Tamura, and Xavier Défago. "Time-Independent Planning for Multiple Moving Agents." Proceedings of the AAAI Conference on Artificial Intelligence 35, no. 13 (May 18, 2021): 11299–307. http://dx.doi.org/10.1609/aaai.v35i13.17347.

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Typical Multi-agent Path Finding (MAPF) solvers assume that agents move synchronously, thus neglecting the reality gap in timing assumptions, e.g., delays caused by an imperfect execution of asynchronous moves. So far, two policies enforce a robust execution of MAPF plans taken as input: either by forcing agents to synchronize or by executing plans while preserving temporal dependencies. This paper proposes an alternative approach, called time-independent planning, which is both online and distributed. We represent reality as a transition system that changes configurations according to atomic actions of agents, and use it to generate a time-independent schedule. Empirical results in a simulated environment with stochastic delays of agents' moves support the validity of our proposal.

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Dig, Danny. "Refactoring for Asynchronous Execution on Mobile Devices." IEEE Software 32, no. 6 (November 2015): 52–61. http://dx.doi.org/10.1109/ms.2015.133.

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Kumar Sahu, Anil, Rashid Sheikh, and A. Surendar. "Ultra low power design approach of asynchronous delta sigma modulator." International Journal of Engineering & Technology 7, no. 1.1 (December 21, 2017): 84. http://dx.doi.org/10.14419/ijet.v7i1.1.8929.

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Asynchronous Delta Sigma Modulator (ADSM) is assuming an extremely vital part in the majority of conveying device and information convertor and in this manner requires the exceptional consideration in outlining. The execution of the vast majority of the device having DSM as an essential segment is described by the execution of the DSM hardware. This paper introduces the audit of work performed in planning of Asynchronous Delta Sigma Modulator. Latest trends are about the utilization of ADSM for various applications. Contrasting the execution of various ADSM circuits, an execution paradigm is settled for ADSM plan. The execution criteria basically think about the Low working voltages, low power utilization, high SNDR and better focus recurrence. At that point a strategy is suggested that characterizes the High execution ADSM that influence joined utilization of various methods to like inverse operation and mass driven MOS for ultra low power outline and enhancing the execution of an Asynchronous Delta Sigma Modulator.

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Mahmood, Ausif, and William I. Baker. "An Evaluation of Parallel Synchronous and Conservative Asynchronous Logic-Level Simulations." VLSI Design 4, no. 2 (January 1, 1996): 91–105. http://dx.doi.org/10.1155/1996/56545.

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A recent paper by Bailey [1] contains a theorem stating that the idealized execution times of unit-delay, synchronous and conservative asynchronous simulations are equal under the conditions that unlimited number of processors are available and the evaluation time of each logic element is equal. Further it is shown that the above conditions result in a lower bound on the execution times of both synchronous and conservative asynchronous simulations. Bailey's above important conclusions are derived under a strict assumption that the inputs to a circuit remain fixed during the entire simulation. We remove this limitation and, by extending the analyses to multi-input, multi-output circuits with an arbitrary number of input events, show that the conservative asynchronous simulation extracts more parallelism and executes faster than synchronous simulation in general. Our conclusions are supported by a comparison of the idealized execution times of synchronous and conservative asynchronous algorithms on ISCAS combinational and sequential benchmark circuits.

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Shudo, Kazuyuki, and Yoichi Muraoka. "Asynchronous migration of execution context in Java Virtual Machines." Future Generation Computer Systems 18, no. 2 (October 2001): 225–33. http://dx.doi.org/10.1016/s0167-739x(00)00100-x.

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Aumann, Yonatan, Michael A. Bender, and Lisa Zhang. "Efficient Execution of Nondeterministic Parallel Programs on Asynchronous Systems." Information and Computation 139, no. 1 (November 1997): 1–16. http://dx.doi.org/10.1006/inco.1997.2653.

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SRIVASTAVA, JAIDEEP, JAU-HWANG WANG, KUO WEI HWANG, and WEI TEK TSAI. "A TRANSACTION MODEL FOR PARALLEL RULE EXECUTION PART I: MODEL AND ALGORITHMS." International Journal on Artificial Intelligence Tools 02, no. 03 (September 1993): 395–429. http://dx.doi.org/10.1142/s0218213093000205.

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This paper introduces a transaction model for parallel production systems, where rules can be fired in a completely asynchronous parallel manner. A model is developed to describe two properties of a serial production system execution, namely, conditional dependence (a rule firing removes another from the conflict set) and prioritization (by the conflict resolution mechanism). These are used as the basis to define the correctness criteria for parallel production execution, namely, conditional serializability, prioritized serializability, and prioritized conditional serializability. A graph model is used to represent production system execution which provides a means of expressing correctness as graph acyclicity, which in turn is used as a basis to develop practical schedulers that manage the concurrent asynchronous production execution and ensure correctness. Two practical schedulers, namely, conditional strict two-phase locking and priority queue scheduler are developed for conditional serializability and prioritized serializability, respectively. They are combined for prioritized conditional serializability.

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UDDIN, M. IRFAN, MICHIEL W. VAN TOL, and CHRIS R. JESSHOPE. "HIGH LEVEL SIMULATION OF SVP MANY-CORE SYSTEMS." Parallel Processing Letters 21, no. 04 (December 2011): 413–38. http://dx.doi.org/10.1142/s0129626411000308.

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The Microgrid is a many-core architecture comprising multiple clusters of fine-grained multi-threaded cores. The SVP API supported by the cores allows for the asynchronous delegation of work to different clusters of cores which can be acquired dynamically. We want to explore the execution of complex applications and their interaction with dynamically allocated resources. To date, any evaluation of the Microgrid has used a detailed emulation with a cycle accurate simulation of the execution time. Although the emulator can be used to evaluate small program kernels, it only executes at a rate of 100K instructions per second, divided over the number of emulated cores. This makes it inefficient to evaluate a complex application executing on many cores using dynamic allocation of clusters. In order to obtain a more efficient evaluation we have developed a co-simulation environment that executes high level SVP control code but which abstracts the scheduling of the low-level threads using two different techniques. The co-simulation is evaluated for both performance and simulation accuracy.

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Hmid, Soukaina N., Jose G. F. Coutinho, and Wayne Luk. "A Transfer-Aware Runtime System for Heterogeneous Asynchronous Parallel Execution." ACM SIGARCH Computer Architecture News 43, no. 4 (April 22, 2016): 40–45. http://dx.doi.org/10.1145/2927964.2927972.

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Corsonello, Pasquale, Stefania Perri, and Giuseppe Cocorullo. "High performance mixed-logic asynchronous datapaths with overlapped execution circuits." International Journal of Electronics 87, no. 10 (October 2000): 1193–208. http://dx.doi.org/10.1080/002072100415648.

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Silva, Jorge, Ana Aguiar, and Fernando Silva. "Parallel Asynchronous Strategies for the Execution of Feature Selection Algorithms." International Journal of Parallel Programming 46, no. 2 (February 9, 2017): 252–83. http://dx.doi.org/10.1007/s10766-017-0493-2.

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Fatoohi, Rod, Nihar Gokhale, and Suja Viswesan. "iJob: an Internet-based job execution environment using asynchronous messaging." Information and Software Technology 47, no. 8 (June 2005): 565–74. http://dx.doi.org/10.1016/j.infsof.2004.10.007.

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Izadkhah, Habib. "Transforming Source Code to Mathematical Relations for Performance Evaluation." Annales Universitatis Mariae Curie-Sklodowska, sectio AI – Informatica 15, no. 2 (September 1, 2015): 7. http://dx.doi.org/10.17951/ai.2015.15.2.7-13.

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Assessing software quality attributes (such as performance, reliability, and security) from source code is of the utmost importance. The performance of a software system can be improved by its parallel and distributed execution. The aim of the parallel and distributed execution is to speed up by providing the maximum possible concurrency in executing the distributed segments. It is a well known fact that distributing a program cannot be always caused speeding up the execution of it; in some cases, this distribution can have negative effects on the running time of the program. Therefore, before distributing a source code, it should be specified whether its distribution could cause maximum possible concurrency or not. The existing methods and tools cannot achieve this aim from the source code. In this paper, we propose a mathematical relationship for object oriented programs that statically analyze the program by verifying the type of synchronous and asynchronous calls inside the source code. Then, we model the invocations of the software methods by Discrete Time Markov Chains (DTMC). Using the properties of DTMC and the proposed mathematical relationship, we will determine whether or not the source code can be distributed on homogeneous processors. The experimental results showed that we can specify whether the program is distributable or not, before deploying it on the distributed systems.

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Bahr, Patrick, and Rasmus Ejlers Møgelberg. "Asynchronous Modal FRP." Proceedings of the ACM on Programming Languages 7, ICFP (August 30, 2023): 476–510. http://dx.doi.org/10.1145/3607847.

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Over the past decade, a number of languages for functional reactive programming (FRP) have been suggested, which use modal types to ensure properties like causality, productivity and lack of space leaks. So far, almost all of these languages have included a modal operator for delay on a global clock. For some applications, however, a global clock is unnatural and leads to leaky abstractions as well as inefficient implementations. While modal languages without a global clock have been proposed, no operational properties have been proved about them, yet. This paper proposes Async RaTT, a new modal language for asynchronous FRP, equipped with an operational semantics mapping complete programs to machines that take asynchronous input signals and produce output signals. The main novelty of Async RaTT is a new modality for asynchronous delay, allowing each output channel to be associated at runtime with the set of input channels it depends on, thus causing the machine to only compute new output when necessary. We prove a series of operational properties including causality, productivity and lack of space leaks. We also show that, although the set of input channels associated with an output channel can change during execution, upper bounds on these can be determined statically by the type system.

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Ferringer, Markus. "On Self-Timed Circuits in Real-Time Systems." International Journal of Reconfigurable Computing 2011 (2011): 1–16. http://dx.doi.org/10.1155/2011/972375.

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While asynchronous logic has many potential advantages compared to traditional synchronous designs, one of the major drawbacks is its unpredictability with respect to temporal behavior. Having no high-precision oscillator, a self-timed circuit's execution speed is heavily dependent on temperature and supply voltage. Small fluctuations of these parameters already result in noticeable changes of the design's throughput and performance. Without further provisions this jitter makes the use of asynchronous logic hardly feasible for real-time applications. We investigate the temporal characteristics of self-timed circuits regarding their usage in real-time systems, especially the Time-Triggered Protocol. We propose a simple timing model and elaborate a self-adapting circuit which shall derive a suitable notion of time for both bit transmission and protocol execution. We further introduce and analyze our jitter compensation concept, which is a threefold mechanism to keep the asynchronous circuit's notion of time tightly synchronized to the remaining communication participants. To demonstrate the robustness of our solution, we perform different tests and investigate their impact on jitter and frequency stability.

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Wang, Xiaofeng, Yu Sun, and Naira Hovakimyan. "Asynchronous task execution in networked control systems using decentralized event-triggering." Systems & Control Letters 61, no. 9 (September 2012): 936–44. http://dx.doi.org/10.1016/j.sysconle.2012.05.010.

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Vokhmianin, H. Ia, O. O. Zhulkovskyi, I. I. Zhulkovska, V. A. Katan, V. Iu Klym, and I. I. Kuznietsov. "Evaluation of the efficiency of implementation of asynchronous computing algorithms using coroutines and threads in С++." System technologies 3, no. 146 (May 11, 2023): 53–60. http://dx.doi.org/10.34185/1562-9945-3-146-2023-06.

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Modern multi-core systems are most effective when used in large server centers and for cloud computing. However, despite the known complexity of software implemen-tation, parallel computing on multiprocessors is increasingly used in computer model-ling. Advanced mechanisms of synchronous and multithreaded programming are in-creasingly used to improve the productivity of numerical studies, reducing the time of computer models implementation. One such mechanism is coroutines, a convenient tool for managing asynchronous operations introduced in the C++20 standard. A special feature of coroutines is the ability to suspend a function at a certain stage, saving its state, and after some time resume its execution from the previous stop. The aim of this research is to improve the performance of computer modelling by using coroutines and data threads. As a result of the work, a test algorithm for multiplying a matrix by a vector and its modified asynchronous version using the coroutine mechanism and splitting into two data threads was developed, which allowed to achieve 1.94 times increase in the com-puting speed when the matrix dimension is 15000 (2.25×106 elements). It has been found that at a small matrix dimension, the developed asynchronous algorithm using coroutines and splitting into two threads is less efficient than the single thread algo-rithm. This is due to the fact that the compiler needs some time to create threads and start execution simultaneously. With a large dimensionality, the performance of the asynchronous algorithm increases significantly. With a matrix dimension of more than 1200, the use of an asynchronous algorithm divided into two threads is guaranteed to be more efficient than a single-threaded. The data obtained are consistent with the results of similar studies of the problem of increasing the efficiency of computer modelling using alternative software and hard-ware. The new method of solving the problems of asynchronous programming provides a more efficient and simple mechanism for managing asynchronous operations.

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Manning, S. M., and D. G. Meyer. "Analysis of Asynchronous Execution Streams with I-Caching in Massively Parallel Systems." Journal of Parallel and Distributed Computing 19, no. 3 (November 1993): 279–91. http://dx.doi.org/10.1006/jpdc.1993.1112.

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Uddin, Irfan. "One-IPC high-level simulation of microthreaded many-core architectures." International Journal of High Performance Computing Applications 31, no. 2 (July 28, 2016): 152–62. http://dx.doi.org/10.1177/1094342015584495.

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The microthreaded many-core architecture is comprised of multiple clusters of fine-grained multi-threaded cores. The management of concurrency is supported in the instruction set architecture of the cores and the computational work in application is asynchronously delegated to different clusters of cores, where the cluster is allocated dynamically. Computer architects are always interested in analyzing the complex interaction amongst the dynamically allocated resources. Generally a detailed simulation with a cycle-accurate simulation of the execution time is used. However, the cycle-accurate simulator for the microthreaded architecture executes at the rate of 100,000 instructions per second, divided over the number of simulated cores. This means that the evaluation of a complex application executing on a contemporary multi-core machine can be very slow. To perform efficient design space exploration we present a co-simulation environment, where the detailed execution of instructions in the pipeline of microthreaded cores and the interactions amongst the hardware components are abstracted. We present the evaluation of the high-level simulation framework against the cycle-accurate simulation framework. The results show that the high-level simulator is faster and less complicated than the cycle-accurate simulator but with the cost of losing accuracy.

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Fukuda, Hiroaki, and Paul Leger. "SyncAS: A Virtual Block Approach to Tame Asynchronous Programming." International Journal of Software Engineering and Knowledge Engineering 25, no. 05 (June 2015): 887–907. http://dx.doi.org/10.1142/s0218194015400252.

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Asynchronous programming has been widely adopted in domains such as Web development. This programming style usually uses callback methods, non-blocking operations, allowing high responsive user interactions even if an application works without multi-threading. However, this style requires the uncoupling of a module into two sub-modules at least, which are not intuitively connected by a callback method. The separation of modules spurs the birth of other issues: callback spaghetti and callback hell. This paper proposes a virtual block approach to address the previous two issues. This approach enables a programmer to virtually block a program execution and restart it at arbitrary points in the program. As a result, programmers do not need to uncouple a module even if non-blocking operations are adopted; therefore, callback dependencies disappear. Using aspect-oriented programming, this approach uses aspects to control the execution of a program in an oblivious manner. As a consequence, programmers do not need to be concerned whether pieces of code use blocking or non-blocking operations. We implement a proof-of-concept for this approach, called SyncAS, for ActionScript3. In addition, we apply our proposal to a toy application and conduct experiments to show its modular application, flexibility, and performance.

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Kovalenko, N. S. "Macropipelined execution of asynchronous processes competing for a limited number of transfer channels." Cybernetics and Systems Analysis 34, no. 5 (September 1998): 759–65. http://dx.doi.org/10.1007/bf02667050.

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Ghosh, Sumit. "An asynchronous approach to efficient execution of programs on adaptive architectures utilizing FPGAs." Journal of Network and Computer Applications 20, no. 3 (July 1997): 223–52. http://dx.doi.org/10.1006/jnca.1997.0052.

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Xiaoguang, Ren, and Xu Xinhai. "AP-IO: Asynchronous Pipeline I/O for Hiding Periodic Output Cost in CFD Simulation." Scientific World Journal 2014 (2014): 1–12. http://dx.doi.org/10.1155/2014/273807.

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Computational fluid dynamics (CFD) simulation often needs to periodically output intermediate results to files in the form of snapshots for visualization or restart, which seriously impacts the performance. In this paper, we present asynchronous pipeline I/O (AP-IO) optimization scheme for the periodically snapshot output on the basis of asynchronous I/O and CFD application characteristics. InAP-IO, dedicated background I/O processes or threads are in charge of handling the file write in pipeline mode, therefore the write overhead can be hidden with more calculation than classic asynchronous I/O. We design the framework ofAP-IOand implement it in OpenFOAM, providing CFD users with a user-friendly interface. Experimental results on theTianhe-2supercomputer demonstrate thatAP-IOcan achieve a good optimization effect for the periodical snapshot output in CFD application, and the effect is especially better for massively parallel CFD simulations, which can reduce the total execution time up to about 40%.

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Rhea, Vanessa Cristina, Marinez Meneghello Passos, and Sergio De Mello Arruda. "Remote Teacher Actions of Mathematics Teachers in Higher Education." Acta Scientiae 24, no. 1 (January 7, 2022): 30–56. http://dx.doi.org/10.17648/acta.scientiae.6801.

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Background: the investigation of teacher actions in face-to-face teaching has become a fertile line of research both in mathematics and in other areas. The pandemic moment that Brazil has been going through since March 2020, which forced teaching to take place remotely, provided conditions for the research to be extended to this type of teaching. Objectives: investigate teacher’s actions in remote education to understand what teachers actually did and do in their classes in this teaching format. Design: This research is characterised as qualitative, with the focus of observation on synchronous and asynchronous classes held by teachers. Setting and Participants: Eleven teachers who teach mathematics in higher education remotely at different institutions in the state of Paraná participated in the research. Data collection and analysis: Data were collected through interviews conducted via Google Meet, recorded, transcribed and analysed using discursive textual analysis. Results: From the analysis, the remote teaching actions were grouped into two moments, called Poscênio [Backstage] and Execution. The Backstage covered a set of seven actions (Self-education, Acquire, Organise, Elaborate, Send, Communicate, and Evaluate) that involved 35 different microactions, when the teacher carried out the preparation of the discipline and classes, as well as their closings asynchronously. The Execution moment comprised six actions (Operationalise, Write, Explain, Answer, Wait, and Interrupt) and 24 microactions, in which the teacher synchronously put into practice what was prepared in Backstage. Conclusions: Based on the results (large number of actions and micro-actions in Backstage), we conclude that remote teaching has required a great effort from teachers in the search for information and elaborate planning for the realisation of classes, which perhaps explains the anxieties revealed by them during interviews.

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Yasuda, Gen'ichi. "Design and Implementation of Distributed Autonomous Coordinators for Cooperative Multi-Robot Systems." International Journal of System Dynamics Applications 5, no. 4 (October 2016): 1–15. http://dx.doi.org/10.4018/ijsda.2016100101.

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The paper presents a systematic method of the design of cooperative task planning and execution for complex robotic systems using multiple robots. Because individual robots can autonomously execute their dedicated tasks, in cooperative multi-robot systems, robotic activities should be designed as discrete event driven asynchronous, concurrent processes. Further, since robotic activities are hierarchically defined, control requirements should be specified in a proper and consistent manner on different levels of control abstraction. In this paper, Petri nets are adopted as a specification tool for task planning and execution by multiple robots. Based on place/transition Petri nets, control conditions for inter-robot cooperation with synchronized interaction are represented, and control rules to achieve distributed autonomous coordinated activities with synchronous and asynchronous communication are proposed. An implementation of net based control software on hierarchical and distributed architecture is presented for an example multi-robot cell, where the higher-level controller executes a global net model of task plan representing cooperative behaviors performed by the robots, and the parallel activities of the individual robots are synchronized through the transmission of requests and the reception of status between the associated lower-level local controllers.

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Roberge, Vincent, Mohammed Tarbouchi, and Francis Okou. "Collaborative Parallel Hybrid Metaheuristics on Graphics Processing Unit." International Journal of Computational Intelligence and Applications 14, no. 01 (March 2015): 1550002. http://dx.doi.org/10.1142/s1469026815500029.

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Metaheuristics are nondeterministic optimization algorithms used to solve complex problems for which classic approaches are unsuitable. Despite their effectiveness, metaheuristics require considerable computational power and cannot easily be used in time critical applications. Fortunately, those algorithms are intrinsically parallel and have been implemented on shared memory systems and more recently on graphics processing units (GPUs). In this paper, we present highly efficient parallel implementations of the particle swarm optimization (PSO), the genetic algorithm (GA) and the simulated annealing (SA) algorithm on GPU using CUDA. Our approach exploits the parallelism at the solution level, follows an island model and allows for speedup up to 346× for different benchmark functions. Most importantly, we also present a strategy that uses the generalized island model to integrate multiple metaheuristics into a parallel hybrid solution adapted to the GPU. Our proposed solution uses OpenMP to heavily exploit the concurrent kernel execution feature of recent NVIDIA GPUs, allowing for the parallel execution of the different metaheuristics in an asynchronous manner. Asynchronous hybrid metaheuristics has been developed for multicore CPU, but never for GPU. The speedup offered by the GPU is far superior and key to the optimization of solutions to complex engineering problems.

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Ben-Asher, Yosi, and Esti Stein. "Basic Algorithms for the Asynchronous Reconfigurable Mesh." VLSI Design 15, no. 1 (January 1, 2002): 441–54. http://dx.doi.org/10.1080/106551402100002057.

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Many constant time algorithms for various problems have been developed for the reconfigurable mesh (RM) in the past decade. All these algorithms are designed to work with synchronous execution, with no regard for the fact that large size RMs will probably be asynchronous. A similar observation about the PRAM model motivated many researchers to develop algorithms and complexity measures for the asynchronous PRAM (APRAM). In this work, we show how to define the asynchronous reconfigurable mesh (ARM) and how to measure the complexity of asynchronous algorithms executed on it. We show that connecting all processors in a row of an n×n ARM (the analog of barrier synchronization in the APRAM model) can be solved with complexity Θ(nlog⁡n). Intuitively, this is average work time for solving such a problem. Next, we describe general a technique for simulating T -step synchronous RM algorithms on the ARM with complexity of Θ(T⋅n2log⁡n). Finally, we consider the simulation of the classical synchronous algorithm for counting the number of non-zero bits in an n bits vector using (k<n)×n RM. By carefully optimizing the synchronization to the specific synchronous algorithm being simulated, one can (at least in the case of counting) improve upon the general simulation.

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García-Valdez, Mario, Alejandra Mancilla, Oscar Castillo, and Juan Julián Merelo-Guervós. "Distributed and Asynchronous Population-Based Optimization Applied to the Optimal Design of Fuzzy Controllers." Symmetry 15, no. 2 (February 9, 2023): 467. http://dx.doi.org/10.3390/sym15020467.

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Designing a controller is typically an iterative process during which engineers must assess the performance of a design through time-consuming simulations; this becomes even more burdensome when using a population-based metaheuristic that evaluates every member of the population. Distributed algorithms can mitigate this issue, but these come with their own challenges. This is why, in this work, we propose a distributed and asynchronous bio-inspired algorithm to execute the simulations in parallel, using a multi-population multi-algorithmic approach. Following a cloud-native pattern, isolated populations interact asynchronously using a distributed message queue, which avoids idle cycles when waiting for other nodes to synchronize. The proposed algorithm can mix different metaheuristics, one for each population, first because it is possible and second because it can help keep total diversity high. To validate the speedup benefit of our proposal, we optimize the membership functions of a fuzzy controller for the trajectory tracking of a mobile autonomous robot using distributed versions of genetic algorithms, particle swarm optimization, and a mixed-metaheuristic configuration. We compare sequential versus distributed implementations and demonstrate the benefits of mixing the populations with distinct metaheuristics. We also propose a simple migration strategy that delivers satisfactory results. Moreover, we compare homogeneous and heterogenous configurations for the populations’ parameters. The results show that even when we use random heterogeneous parameter configuration in the distributed populations, we obtain an error similar to that in other work while significantly reducing the execution time.

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Dewangan, Ram Kishan, Anupam Shukla, and W. Wilfred Godfrey. "A solution for priority-based multi-robot path planning problem with obstacles using ant lion optimization." Modern Physics Letters B 34, no. 13 (March 18, 2020): 2050137. http://dx.doi.org/10.1142/s0217984920501377.

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This paper provides a Priority-based Optimized-Hybrid Asynchronous Centralized and Decentralized (POHACD) algorithm for multi-robot path planning (MRPP) issue, where multiple robots communicate with each other, as well as through collision check makes their decision. The priority-based approach provides priority to each robot thus bypassing another robot in conflict situation. Optimization lies in terms of minimal path length. The proposed hybrid asynchronous algorithm leverages the centralized approach to improve the overall system efficiency and distributed approach to reduce communication overhead, which automatically reduces execution time. This algorithm prevents unnecessary communication by transmitting global information and in the meantime limits specific information that is only in the interest of certain robots. By carrying out the simulations, it has been demonstrated that the ant lion optimization for prioritized planning performs better in all the roadmaps.

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Mesin, Luca, Usman Ghani, and Imran Khan Niazi. "Non-Linear Adapted Spatio-Temporal Filter for Single-Trial Identification of Movement-Related Cortical Potential." Electronics 12, no. 5 (March 5, 2023): 1246. http://dx.doi.org/10.3390/electronics12051246.

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The execution or imagination of a movement is reflected by a cortical potential that can be recorded by electroencephalography (EEG) as Movement-Related Cortical Potentials (MRCPs). The identification of MRCP from a single trial is a challenging possibility to get a natural control of a Brain–Computer Interface (BCI). We propose a novel method for MRCP detection based on optimal non-linear filters, processing different channels of EEG including delayed samples (getting a spatio-temporal filter). Different outputs can be obtained by changing the order of the temporal filter and of the non-linear processing of the input data. The classification performances of these filters are assessed by cross-validation on a training set, selecting the best ones (adapted to the user) and performing a majority voting from the best three to get an output using test data. The method is compared to another state-of-the-art filter recently introduced by our group when applied to EEG data recorded from 16 healthy subjects either executing or imagining 50 self-paced upper-limb palmar grasps. The new approach has a median accuracy on the overall dataset of 80%, which is significantly better than that of the previous filter (i.e., 63%). It is feasible for online BCI system design with asynchronous, self-paced applications.

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Foldi, Tamas, Chris von Csefalvay, and Nicolas A. Perez. "JAMPI: Efficient Matrix Multiplication in Spark Using Barrier Execution Mode." Big Data and Cognitive Computing 4, no. 4 (November 5, 2020): 32. http://dx.doi.org/10.3390/bdcc4040032.

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The new barrier mode in Apache Spark allows for embedding distributed deep learning training as a Spark stage to simplify the distributed training workflow. In Spark, a task in a stage does not depend on any other tasks in the same stage, and hence it can be scheduled independently. However, several algorithms require more sophisticated inter-task communications, similar to the MPI paradigm. By combining distributed message passing (using asynchronous network IO), OpenJDK’s new auto-vectorization and Spark’s barrier execution mode, we can add non-map/reduce-based algorithms, such as Cannon’s distributed matrix multiplication to Spark. We document an efficient distributed matrix multiplication using Cannon’s algorithm, which significantly improves on the performance of the existing MLlib implementation. Used within a barrier task, the algorithm described herein results in an up to 24% performance increase on a 10,000 × 10,000 square matrix with a significantly lower memory footprint. Applications of efficient matrix multiplication include, among others, accelerating the training and implementation of deep convolutional neural network-based workloads, and thus such efficient algorithms can play a ground-breaking role in the faster and more efficient execution of even the most complicated machine learning tasks.

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Han, Jian Ping, Xiao Yang Li, Da Xing Zhang, and Bo Ting Geng. "Fast Background Subtraction Based on GPU." Advanced Materials Research 341-342 (September 2011): 737–42. http://dx.doi.org/10.4028/www.scientific.net/amr.341-342.737.

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In this paper, a fast background subtraction algorithm using codebook model is presented to extract moving objects from surveillance videos. The time for stopped objects being absorbed into the background can be controlled to deal with different applications and have nothing to do with the complexity of the scene. We implement the algorithm on GPU using CUDA, and optimize the implementation using pinned memory and asynchronous execution techniques. Experimental results are provided to demonstrate the accuracy, effectiveness, and efficiency of the proposed algorithm.

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López, Mario Rossainz, Ivo H. Pineda-Torres, Ivan Olmos Pineda, and José Arturo Olvera López. "Parallel Object Compositions for the Search of Sequences DNA Strings in the Construction of Gnomes." International Journal of Privacy and Health Information Management 7, no. 1 (January 2019): 18–44. http://dx.doi.org/10.4018/ijphim.2019010102.

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Within an environment of parallel objects, an approach of structured parallel programming and the paradigm of the orientation to objects show a programming method based on high level parallel compositions or HLPCs to solve two problems of combinatorial optimization: grouping fragments of DNA sequences and the parallel exhaustive search (PES) of RNA strings that help the sequence and the assembly of DNAs. The pipeline and farm models are shown as HLPCs under the object orientation paradigm and with them it is proposed the creation of a new HLPCs that combines and uses the previous ones to solve the cited problems. Each HLPC proposal contains a set of predefined synchronization constraints between processes, as well as the use of synchronous, asynchronous and asynchronous future modes of communication. This article shows the algorithms that solve the problems, their design and implementation as HLPCs and the performance metrics in their parallel execution using multicores and video accelerator card.

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Simões, David, Nuno Lau, and Luís Paulo Reis. "Multi Agent Deep Learning with Cooperative Communication." Journal of Artificial Intelligence and Soft Computing Research 10, no. 3 (July 1, 2020): 189–207. http://dx.doi.org/10.2478/jaiscr-2020-0013.

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AbstractWe consider the problem of multi agents cooperating in a partially-observable environment. Agents must learn to coordinate and share relevant information to solve the tasks successfully. This article describes Asynchronous Advantage Actor-Critic with Communication (A3C2), an end-to-end differentiable approach where agents learn policies and communication protocols simultaneously. A3C2 uses a centralized learning, distributed execution paradigm, supports independent agents, dynamic team sizes, partially-observable environments, and noisy communications. We compare and show that A3C2 outperforms other state-of-the-art proposals in multiple environments.

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Albert, Elvira, Nikolaos Bezirgiannis, Frank de Boer, and Enrique Martin-Martin. "A Formal, Resource Consumption-Preserving Translation from Actors with Cooperative Scheduling to Haskell*." Fundamenta Informaticae 177, no. 3-4 (December 10, 2020): 203–34. http://dx.doi.org/10.3233/fi-2020-1988.

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We present a formal translation of a resource-aware extension of the Abstract Behavioral Specification (ABS) language to the functional language Haskell. ABS is an actor-based language tailored to the modeling of distributed systems. It combines asynchronous method calls with a suspend and resume mode of execution of the method invocations. To cater for the resulting cooperative scheduling of the method invocations of an actor, the translation exploits for the compilation of ABS methods Haskell functions with continuations. The main result of this article is a correctness proof of the translation by means of a simulation relation between a formal semantics of the source language and a high-level operational semantics of the target language, i.e., a subset of Haskell. We further prove that the resource consumption of an ABS program extended with a cost model is preserved over this translation, as we establish an equivalence of the cost of executing the ABS program and its corresponding Haskell-translation. Concretely, the resources consumed by the original ABS program and those consumed by the Haskell program are the same, considering a cost model. Consequently, the resource bounds automatically inferred for ABS programs extended with a cost model, using resource analysis tools, are sound resource bounds also for the translated Haskell programs. Our experimental evaluation confirms the resource preservation over a set of benchmarks featuring different asymptotic costs.

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Morrow, Tom M., and Sumit Ghosh. "DIVIDE: Distributed visual display of the execution of asynchronous, distributed algorithms on loosely coupled parallel processors." Computers & Graphics 18, no. 6 (November 1994): 849–59. http://dx.doi.org/10.1016/0097-8493(94)90012-4.

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Wolfmann, Gustavo. "Parallel Execution on HeterogeneousMultiprocessors from Algorithm Models Based on Petri Nets." EQUATIONS 1 (July 14, 2021): 47–54. http://dx.doi.org/10.37394/232021.2021.1.7.

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Current supercomputers are composed by nodes containing a combination of general purpose computing units (CPUs) and specific mathematical coprocessors. In this way, GPGPUs or Xeon Phi cards are attached to the nodes to improve its performance. Both types of processors, CPUs and coprocessors, have many differences, like their architecture, the clock rate of the processors and the operation of the related memory. These are the main factors that conform an heterogeneous multiprocessor. A parallel program that wants to achieve the sum of the performance of both types of processors, must consider not only the complexity of the parallel algorithm, but also the differences in the architecture of processors, increasing its complexity. As a contribution on this problem, this paper presents a model of parallel execution based on Petri Nets, called PN-PEM, that is used not only to model a parallel algorithm, but also to execute it directly on a computer with heterogeneous multiprocessors. An asynchronous execution of tasks and a dynamic scheduler are the main characteristics that allow execute a parallel program on this type of parallel computer. Tests done on a multicore computer with two Xeon Phi cards reach the aggregate performance of both type of processors, confirming the quality of the model used.

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ANTOY, SERGIO, and MICHAEL HANUS. "FUNCTIONAL PEARL Concurrent distinct choices." Journal of Functional Programming 14, no. 6 (October 27, 2004): 657–68. http://dx.doi.org/10.1017/s095679680400509x.

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An injective finite mapping is an abstraction common to many programs. We describe the design of an injective finite mapping and its implementation in Curry, a functional logic language. Curry supports the concurrent asynchronous execution of distinct portions of a program. This condition prevents passing from one portion to another a structure containing a partially constructed mapping to ensure that a new choice does not violate the injectivity condition. We present some motivating problems and we show fragments of programs that solve these problems using our design and implementation.

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Karasinski, John A., Isabel C. Torron Valverde, Holly L. Brosnahan, Jack W. Gale, Ron Kim, Melodie Yashar, and Jessica J. Marquez. "Designing Procedure Execution Tools with Emerging Technologies for Future Astronauts." Applied Sciences 11, no. 4 (February 10, 2021): 1607. http://dx.doi.org/10.3390/app11041607.

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NASA’s human spaceflight efforts are moving towards long-duration exploration missions requiring asynchronous communication between onboard crew and an increasingly remote ground support. In current missions aboard the International Space Station, there is a near real-time communication loop between Mission Control Center and astronauts. This communication is essential today to support operations, maintenance, and science requirements onboard, without which many tasks would no longer be feasible. As NASA takes the next leap into a new era of human space exploration, new methods and tools compensating for the lack of continuous, real-time communication must be explored. The Human-Computer Interaction Group at NASA Ames Research Center has been investigating emerging technologies and their applicability to increase crew autonomy in missions beyond low Earth orbit. Interactions using augmented reality and the Internet of Things have been researched as possibilities to facilitate usability within procedure execution operations. This paper outlines four research efforts that included technology demonstrations and usability studies with prototype procedure tools implementing emerging technologies. The studies address habitat feedback integration, analogous procedure testing, task completion management, and crew training. Through these technology demonstrations and usability studies, we find that low- to medium-fidelity prototypes, evaluated early in the design process, are both effective for garnering stakeholder buy-in and developing requirements for future systems. In this paper, we present the findings of the usability studies for each project and discuss ways in which these emerging technologies can be integrated into future human spaceflight operations.

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Peng, Zeshun, Yanfeng Zhang, Qian Xu, Haixu Liu, Yuxiao Gao, Xiaohua Li, and Ge Yu. "NeuChain." Proceedings of the VLDB Endowment 15, no. 11 (July 2022): 2585–98. http://dx.doi.org/10.14778/3551793.3551816.

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Blockchain serves as a replicated transactional processing system in a trustless distributed environment. Existing blockchain systems all rely on an explicit ordering step to determine the global order of transactions that are collected from multiple peers. The ordering consensus can be the bottleneck since it must be Byzantine-fault tolerant and can scarcely benefit from parallel execution. In this paper, we propose an ordering-free architecture that makes ordering implicit through deterministic execution. Based on this novel architecture, we develop a permissioned blockchain system NeuChain. A number of key optimizations such as asynchronous block generation and pipelining are leveraged for high throughput and low latency. Several security mechanisms are also designed to make our system robust to malicious attacks. Our geo-distributed experimental results show that NeuChain can achieve 47.2--64.1X throughput improvement over HyperLedger Fabric and 1.6--12.2X throughput improvement over the state-of-the-art high performance blockchains.

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Pérez-Carro, Pascual, Francisco Grimaldo, Miguel Lozano, and Juan M. Orduña. "Characterization of the Jason Multiagent Platform on Multicore Processors." Scientific Programming 22, no. 1 (2014): 21–35. http://dx.doi.org/10.1155/2014/576907.

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Multiagent platforms need to be evaluated focusing on the underlying computer architecture in order to allow developers to exploit the parallelism available in multicore processors. This paper presents the characterization of Jason, a well-known Java-based multiagent platform, when executed on distributed shared memory architectures. Since this kind of architecture is already present in current multicore processors, this should be the first step for the characterization of this platform on distributed systems. To this end, we propose the execution of a set of benchmarks recently proposed for evaluating multiagent platforms. The results obtained show that Jason can be used to program CPU-intensive multiagent applications without loosing the Java scalability over multicore processors. Though, Jason's performance for communication-intensive applications depends on the traffic pattern generated by the agents, the layout of the cores and the selected execution mode (i.e. synchronous or asynchronous).

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Journal articles on the topic 'Asynchronous Executions'

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