Search results for "Tipa"

2014

Here we investigate the connection between topological order and the geometric entanglement, as measured by the logarithm of the overlap between a given state and its closest product state of blocks. We do this for a variety of topologically-ordered systems such as the toric code, double semion, color code, and quantum double models. As happens for the entanglement entropy, we find that for sufficiently large block sizes the geometric entanglement is, up to possible sub-leading corrections, the sum of two contributions: a bulk contribution obeying a boundary law times the number of blocks, and a contribution quantifying the underlying pattern of long-range entanglement of the topologically-…

Repeated pull-through surgery for complicated Hirschsprung's disease--principles derived from clinical experience.

2007

Abstract Background In some patients, an initial pull-through procedure for Hirschsprung's disease fails, and obstructive symptoms persist or recur. Then a repeated pull-through operation may be necessary. Methods Seventeen patients with Hirschsprung's disease aged 2 to 9 years (median, 4.6 years) have undergone a repeated pull-through procedure because of unresponsive symptoms after an initial operation. The initial procedure was Soave in 3 patients, Rehbein in 13 patients, and Duhamel in 1 patient. Surgical revision was indicated by incomplete resection of the transition zone in 16 patients, anastomotic strictures in 9 patients, and fistulas in 2 patients. All 17 patients have undergone R…

Precision Physics in Penning Traps Using the Continuous Stern-Gerlach Effect

2021

Abstract“A single atomic particle forever floating at rest in free space” (H. Dehmelt) would be the ideal object for precision measurements of atomic properties and for tests of fundamental theories. Such an ideal, of course, can ultimately never be achieved. A very close approximation to this ideal is made possible by ion traps, where electromagnetic forces are used to confine charged particles under well-controlled conditions for practically unlimited time. Concurrently, sensitive detection methods have been developed to allow observation of single stored ions. Various cooling methods can be employed to bring the trapped ion nearly to rest. Among different realisations of ion traps we con…

Cost-Efficient On-Chip Routing Implementations for CMP and MPSoC Systems

2011

[EN] The high-performance computing domain is enriching with the inclusion of networks-on-chip (NoCs) as a key component of many-core (CMPs or MPSoCs) architectures. NoCs face the communication scalability challenge while meeting tight power, area, and latency constraints. Designers must address new challenges that were not present before. Defective components, the enhancement of application-level parallelism, or power-aware techniques may break topology regularity, thus, efficient routing becomes a challenge. This paper presents universal logic-based distributed routing (uLBDR), an efficient logic-based mechanism that adapts to any irregular topology derived from 2-D meshes, instead of usi…

Power-constrained sensor selection and routing for cooperative detection in cognitive radios

2012

Given a spectrum-sensing network, a set of active nodes jointly aggregate sensed data at a preset frequency-band and simultaneously route this information to an arbitrarily chosen querying node through a power-constrained multi-hop path. Locally, each sensor node is assumed to be an energy-based detector. This work focuses on deriving algorithms that jointly optimize sensor selection and cooperative detection from which a power-efficient route to the querying node can be established, and then, a tree routing structure spanning the chosen nodes is constructed under a power budget constraint. Sensor information is sequentially aggregated along this optimized routing structure up to the queryi…

Distributed routing and channel allocation in multi-channel multi-hop ad hoc networks

2013

In this paper, we propose a novel routing protocol which is integrated with channel assignment for multi-channel multi-hop wireless ad hoc networks. In such a network, each node is equipped with three transceivers. One is always tuned on a control channel which is responsible for control and broadcast messages, and the other two perform as transmitter and receiver respectively for traffic flows on different data channels. The routing protocol works in an on-demand manner, and the proposed routing discovery process selects a path that potentially traverses nodes with lighter traffic load and lower number of carried flows. With a given number of non-overlapping channels, the optimal solution …

A combined relay-selection and routing protocol for cooperative wireless sensor networks

2012

International audience; In wireless sensor networks several constraints decrease communications performances. In fact, channel randomness and energy restrictions make classical routing protocols inefficient. Therefore, the design of new routing protocols that cope with these constraints become mandatory. The main objective of this paper is to present a multi-objective routing algorithm RBCR that computes routing path based on the energy consumption and channel qualities. Additionally, the channel qualities are evaluated based on the presence of relay nodes. Compared to AODV and AODV associated to a cooperative MAC protocol, RBCR provides better performances in term of delivery ratio, power …

Distance Constrained Mapping to Support NoC Platforms Based on Source Routing

2010

Efficient NoC is crucial for communication among processing elements in a highly parallel processing systems on chip. Mapping cores to slots in a NoC platform and designing efficient routing algorithms are two key problems in NoC design. Source routing offers major advantages over distributed routing especially for regular topology NoC platforms. But it suffers from a serious drawback of overhead since it requires whole communication path to be stored in every packet header. In this paper, we present a core mapping technique which helps to achieve a mapping with the constraint over the path length. We have found that the path length constraint of just 50% is sufficient in most cases. We als…

A Network Protocol to Enhance Robustness in Tree-Based WSNs Using Data Aggregation

2007

This paper proposes a data gathering strategy for wireless sensor networks and an implementation based on the IEEE 802.15.4 standard. The algorithm combines the benefits of single-path and multi-path routing strategies in a hybrid solution which makes use of alternative paths when necessary. We adopt a caching and retransmission technique, which exploits some peculiar features of data aggregation, with the use of implicit acknowledgments of reception. The paper also discusses simulation results that show how the mentioned techniques, combined with exploitation of the features of the IEEE 802.15.4 standard have been used to obtain an efficient protocol that takes energy consumption into acco…

Accurate reliability and availability models for direct interconnection networks

2001

Fault tolerance in multicomputer interconnection networks has been traditionally studied by determining the worst possible combination of faulty components that causes its failure and then assuming that this will occur. But, the probability of the worst possible combination is usually low, and the routing algorithm may be able to find a route between source and destination nodes. The network dependability parameters computed according to this approach will be underestimated. In this paper we propose a methodology for accurately evaluating interconnection network dependability. In addition, we apply it to obtain an accurate estimation of the reliability and availability parameters in a 2-D m…