Search results for " computing"
showing 10 items of 2075 documents
A comparative study of partitioning methods for crowd simulations
2010
The simulation of large crowds of autonomous agents with realistic behavior is still a challenge for several computer research communities. In order to handle large crowds, some scalable architectures have been proposed. Nevertheless, the effective use of distributed systems requires the use of partitioning methods that can properly distribute the workload generated by agents among the existing distributed resources. In this paper, we analyze the use of irregular shape regions (convex hulls) for solving the partitioning problem. We have compared a partitioning method based on convex hulls with two techniques that use rectangular regions. The performance evaluation results show that the conv…
Multi-user interference mitigation under limited feedback requirements for WCDMA systems with base station cooperation
2016
One of the techniques that has been recently identified for dealing with multi-user interference (MUI) in future communications systems is base station (BS) cooperation or joint processing. However, perfect MUI cancellation with this technique demands severe synchronization requirements, perfect and global channel state information (CSI), and an increased backhaul and signaling overhead. In this paper, we consider a more realistic layout with the aim of mitigating the MUI, where only local CSI is available at the BSs. Due to synchronization inaccuracies and errors in the channel estimation, the system becomes partially asynchronous. In the downlink of wideband code division multiple access …
Decentralized Coordination System for Multiple AGVs in a Structured Environment
2011
Abstract In this paper, we propose a decentralized coordination algorithm for safe and efficient management of a group of mobile robots following predefined paths in a dynamic industrial environment. The proposed algorithm is based on shared resources and proved to guarantee ordered traffic flows avoiding collisions and deadlocks. In consistency with the model of distributed robotic systems (DRS), no centralized mechanism, synchronized clock, shared memory or ground support is needed. A local inter-robot communication is required among a small number of spatially adjacent robotic units.
Cell-List based Molecular Dynamics on Many-Core Processors: A Case Study on Sunway TaihuLight Supercomputer
2020
Molecular dynamics (MD) simulations are playing an increasingly important role in several research areas. The most frequently used potentials in MD simulations are pair-wise potentials. Due to the memory wall, computing pair-wise potentials on many-core processors are usually memory bounded. In this paper, we take the SW26010 processor as an exemplary platform to explore the possibility to break the memory bottleneck by improving data reusage via cell-list-based methods. We use cell-lists instead of neighbor-lists in the potential computation, and apply a number of novel optimization methods. Theses methods include: an adaptive replica arrangement strategy, a parameter profile data structur…
Pairwise DNA Sequence Alignment Optimization
2015
This chapter presents a parallel implementation of the Smith-Waterman algorithm to accelerate the pairwise alignment of DNA sequences. This algorithm is especially computationally demanding for long DNA sequences. Parallelization approaches are examined in order to deeply explore the inherent parallelism within Intel Xeon Phi coprocessors. This chapter looks at exploiting instruction-level parallelism within 512-bit single instruction multiple data instructions (vectorization) as well as thread-level parallelism over the many cores (multithreading using OpenMP). Between coprocessors, device-level parallelism through the compute power of clusters including Intel Xeon Phi coprocessors using M…
Set-valued consensus for distributed clock synchronization
2009
This paper addresses the clock synchronization problem in a wireless sensor network (WSN) and proposes a distributed solution that consists of a form of consensus, where agents are able to exchange data representing intervals or sets. The solution is based on a centralized algorithm for clock synchronization, proposed by Marzullo, that determines the smallest interval that is in common with the maximum number of measured intervals. We first show how to convert such an algorithm into a problem involving only operations on sets, and then we convert it into a set–valued consensus. The solution is valid for more general scenarios where agents have uncertain measures of e.g. the position of an o…
Learning-automaton-based online discovery and tracking of spatiotemporal event patterns.
2013
Discovering and tracking of spatiotemporal patterns in noisy sequences of events are difficult tasks that have become increasingly pertinent due to recent advances in ubiquitous computing, such as community-based social networking applications. The core activities for applications of this class include the sharing and notification of events, and the importance and usefulness of these functionalities increase as event sharing expands into larger areas of one's life. Ironically, instead of being helpful, an excessive number of event notifications can quickly render the functionality of event sharing to be obtrusive. Indeed, any notification of events that provides redundant information to the…
Automated Synthesis of Application-layer Connectors from Automata-based Specifications
2019
Abstract Ubiquitous and Pervasive Computing, and the Internet of Things, promote dynamic interaction among heterogeneous systems. To achieve this vision, interoperability among heterogeneous systems represents a key enabler, and mediators are often built to solve protocol mismatches. Many approaches propose the synthesis of mediators. Unfortunately, a rigorous characterization of the concept of interoperability is still lacking, hence making hard to assess their applicability and soundness. In this paper, we provide a framework for the synthesis of mediators that allows us to: (i) characterize the conditions for the mediator existence and correctness; and (ii) establish the applicability bo…
Lambda+, the renewal of the Lambda Architecture: Category Theory to the rescue
2021
Designing software architectures for Big Data is a complex task that has to take into consideration multiple parameters, such as the expected functionalities, the properties that are untradeable, or the suitable technologies. Patterns are abstractions that guide the design of architectures to reach the requirements. One of the famous patterns is the Lambda Architecture, which proposes real-time computations with correctness and fault-tolerance guarantees. But the Lambda has also been highly criticized, mostly because of its complexity and because the real-time and correctness properties are each effective in a different layer but not in the overall architecture. Furthermore, its use cases a…
A systematic comparison of kinetic modelling methods generating parametric maps for [11C]-(R)-PK11195
2006
[(11)C]-(R)-PK11195 is presently the most widely used radiotracer for the monitoring of microglia activity in the central nervous system (CNS). Microglia, the resident immune cells of the brain, play a critical role in acute and chronic diseases of the central nervous system and in host defence against neoplasia. The purpose of this investigation was to evaluate the reliability and sensitivity of five kinetic modelling methods for the formation of parametric maps from dynamic [(11)C]-(R)-PK11195 studies. The methods we tested were the simplified reference tissue model (SRTM), basis pursuit, a simple target-to-reference ratio, the Logan plot and a wavelet based Logan plot. For the reliabilit…