154,439 research outputs found
dOpenCL: Towards a Uniform Programming Approach for Distributed Heterogeneous Multi-/Many-Core Systems
Modern computer systems are becoming increasingly heterogeneous by comprising multi-core CPUs, GPUs, and other accelerators. Current programming approaches for such systems usually require the application developer to use a combination of several programming models (e. g., MPI with OpenCL or CUDA) in order to exploit the full compute
capability of a system.
In this paper, we present dOpenCL (Distributed OpenCL) – a uniform approach to programming distributed heterogeneous systems with accelerators. dOpenCL extends the OpenCL standard, such that arbitrary computing devices installed on any node of a distributed system can be used together within a single application. dOpenCL allows moving data and program
code to these devices in a transparent, portable manner. Since dOpenCL is designed as a fully-fledged implementation of the OpenCL API, it allows running existing OpenCL applications in a heterogeneous distributed environment without any modifications. We describe in detail the mechanisms that are required to implement OpenCL for distributed systems, including a device management mechanism for running multiple applications concurrently. Using three application studies, we compare the performance of dOpenCL with MPI+OpenCL and a standard OpenCL implementation
Time-and event-driven communication process for networked control systems: A survey
Copyright © 2014 Lei Zou et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.In recent years, theoretical and practical research topics on networked control systems (NCSs) have gained an increasing interest from many researchers in a variety of disciplines owing to the extensive applications of NCSs in practice. In particular, an urgent need has arisen to understand the effects of communication processes on system performances. Sampling and protocol are two fundamental aspects of a communication process which have attracted a great deal of research attention. Most research focus has been on the analysis and control of dynamical behaviors under certain sampling procedures and communication protocols. In this paper, we aim to survey some recent advances on the analysis and synthesis issues of NCSs with different sampling procedures (time-and event-driven sampling) and protocols (static and dynamic protocols). First, these sampling procedures and protocols are introduced in detail according to their engineering backgrounds as well as dynamic natures. Then, the developments of the stabilization, control, and filtering problems are systematically reviewed and discussed in great detail. Finally, we conclude the paper by outlining future research challenges for analysis and synthesis problems of NCSs with different communication processes.This work was supported in part by the National Natural Science Foundation of China under Grants 61329301, 61374127, and 61374010, the Royal Society of the UK, and the Alexander von Humboldt Foundation of Germany
Failover in cellular automata
A cellular automata (CA) configuration is constructed that exhibits emergent
failover. The configuration is based on standard Game of Life rules. Gliders
and glider-guns form the core messaging structure in the configuration. The
blinker is represented as the basic computational unit, and it is shown how it
can be recreated in case of a failure. Stateless failover using primary-backup
mechanism is demonstrated. The details of the CA components used in the
configuration and its working are described, and a simulation of the complete
configuration is also presented.Comment: 16 pages, 15 figures and associated video at
http://dl.dropbox.com/u/7553694/failover_demo.avi and simulation at
http://dl.dropbox.com/u/7553694/failover_simulation.ja
Static Safety for an Actor Dedicated Process Calculus by Abstract Interpretation
The actor model eases the definition of concurrent programs with non uniform
behaviors. Static analysis of such a model was previously done in a data-flow
oriented way, with type systems. This approach was based on constraint set
resolution and was not able to deal with precise properties for communications
of behaviors. We present here a new approach, control-flow oriented, based on
the abstract interpretation framework, able to deal with communication of
behaviors. Within our new analyses, we are able to verify most of the previous
properties we observed as well as new ones, principally based on occurrence
counting
Integration of heterogeneous devices and communication models via the cloud in the constrained internet of things
As the Internet of Things continues to expand in the coming years, the need for services that span multiple IoT application domains will continue to increase in order to realize the efficiency gains promised by the IoT. Today, however, service developers looking to add value on top of existing IoT systems are faced with very heterogeneous devices and systems. These systems implement a wide variety of network connectivity options, protocols (proprietary or standards-based), and communication methods all of which are unknown to a service developer that is new to the IoT. Even within one IoT standard, a device typically has multiple options for communicating with others. In order to alleviate service developers from these concerns, this paper presents a cloud-based platform for integrating heterogeneous constrained IoT devices and communication models into services. Our evaluation shows that the impact of our approach on the operation of constrained devices is minimal while providing a tangible benefit in service integration of low-resource IoT devices. A proof of concept demonstrates the latter by means of a control and management dashboard for constrained devices that was implemented on top of the presented platform. The results of our work enable service developers to more easily implement and deploy services that span a wide variety of IoT application domains
Stabilizing Consensus with Many Opinions
We consider the following distributed consensus problem: Each node in a
complete communication network of size initially holds an \emph{opinion},
which is chosen arbitrarily from a finite set . The system must
converge toward a consensus state in which all, or almost all nodes, hold the
same opinion. Moreover, this opinion should be \emph{valid}, i.e., it should be
one among those initially present in the system. This condition should be met
even in the presence of an adaptive, malicious adversary who can modify the
opinions of a bounded number of nodes in every round.
We consider the \emph{3-majority dynamics}: At every round, every node pulls
the opinion from three random neighbors and sets his new opinion to the
majority one (ties are broken arbitrarily). Let be the number of valid
opinions. We show that, if , where is a
suitable positive constant, the 3-majority dynamics converges in time
polynomial in and with high probability even in the presence of an
adversary who can affect up to nodes at each round.
Previously, the convergence of the 3-majority protocol was known for
only, with an argument that is robust to adversarial errors. On
the other hand, no anonymous, uniform-gossip protocol that is robust to
adversarial errors was known for
A mosaic of eyes
Autonomous navigation is a traditional research topic in intelligent robotics and vehicles, which requires a robot to perceive its environment through onboard sensors such as cameras or laser scanners, to enable it to drive to its goal. Most research to date has focused on the development of a large and smart brain to gain autonomous capability for robots. There are three fundamental questions to be answered by an autonomous mobile robot: 1) Where am I going? 2) Where am I? and 3) How do I get there? To answer these basic questions, a robot requires a massive spatial memory and considerable computational resources to accomplish perception, localization, path planning, and control. It is not yet possible to deliver the centralized intelligence required for our real-life applications, such as autonomous ground vehicles and wheelchairs in care centers. In fact, most autonomous robots try to mimic how humans navigate, interpreting images taken by cameras and then taking decisions accordingly. They may encounter the following difficulties
Nonuniform Coverage Control on the Line
This paper investigates control laws allowing mobile, autonomous agents to
optimally position themselves on the line for distributed sensing in a
nonuniform field. We show that a simple static control law, based only on local
measurements of the field by each agent, drives the agents close to the optimal
positions after the agents execute in parallel a number of
sensing/movement/computation rounds that is essentially quadratic in the number
of agents. Further, we exhibit a dynamic control law which, under slightly
stronger assumptions on the capabilities and knowledge of each agent, drives
the agents close to the optimal positions after the agents execute in parallel
a number of sensing/communication/computation/movement rounds that is
essentially linear in the number of agents. Crucially, both algorithms are
fully distributed and robust to unpredictable loss and addition of agents
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