Search results for " Low"
showing 10 items of 972 documents
How Low Can Approximate Degree and Quantum Query Complexity Be for Total Boolean Functions?
2012
It has long been known that any Boolean function that depends on n input variables has both degree and exact quantum query complexity of Omega(log n), and that this bound is achieved for some functions. In this paper we study the case of approximate degree and bounded-error quantum query complexity. We show that for these measures the correct lower bound is Omega(log n / loglog n), and we exhibit quantum algorithms for two functions where this bound is achieved.
On the effect of analog noise in discrete-time analog computations
1998
We introduce a model for analog computation with discrete time in the presence of analog noise that is flexible enough to cover the most important concrete cases, such as noisy analog neural nets and networks of spiking neurons. This model subsumes the classical model for digital computation in the presence of noise. We show that the presence of arbitrarily small amounts of analog noise reduces the power of analog computational models to that of finite automata, and we also prove a new type of upper bound for the VC-dimension of computational models with analog noise.
Ultra-Low Power Wake-up Radio for 5G IoT
2019
5G Internet of Things (5G IoT), which is currently under development by 3GPP, paves the way for connecting diverse categories of devices to the IoT via cellular networks. For battery-powered low-cost IoT devices, wake-up radio (WuR) appears as an eminent technique for prolonging the lifetime of such devices, thanks to its outstanding energy consumption performance. However, only some small-size battery-powered IoT devices are able to transmit to a cellular IoT base station (BS) directly. In this article, we present W2B-IoT, a prototype implementation of a WuR-based two-tier system, which bridges cellular IoT BS and WuR via a Bluetooth low energy (BLE)-enabled Android smartphone. Such a WuR-…
High Precision Conservative Surface Mesh Generation for Swept Volumes
2015
We present a novel, efficient, and flexible scheme to generate a high-quality mesh that approximates the outer boundary of a swept volume. Our approach comes with two guarantees. First, the approximation is conservative, i.e., the swept volume is enclosed by the generated mesh. Second, the one-sided Hausdorff distance of the generated mesh to the swept volume is upper bounded by a user defined tolerance. Exploiting this tolerance the algorithm generates a mesh that is adapted to the local complexity of the swept volume boundary, keeping the overall output complexity remarkably low. The algorithm is two-phased: the actual sweep and the mesh generation. In the sweeping phase, we introduce a g…
Dynamic Channel Aggregation Strategies in Cognitive Radio Networks with Spectrum Adaptation
2011
In cognitive radio networks, channel aggregation techniques which combine several channels together as one channel have been proposed in many MAC protocols. In this paper, spectrum adaptation is proposed in channel aggregation and two strategies which dynamically adjust channel occupancy of ongoing traffic flows are further developed. The performance of these strategies is evaluated using continuous time Markov chain models. Moreover, models in the quasi-stationary regime are analyzed and the closed-form capacity expression is derived in this regime. Numerical results demonstrate that the capacity of the secondary network can be improved by using channel aggregation with spectrum adaptation.
Parameter optimization for amplify-and-forward relaying systems with pilot symbol assisted modulation scheme
2009
Article published in the journal:Wireless Sensor Network Also available from publisher: http://dx.doi.org/10.4236/wsn.2009.11003 Cooperative diversity is a promising technology for future wireless networks. In this paper, we consider a cooperative communication system operating in an amplify-and-forward (AF) mode with a pilot symbol assisted modulation (PSAM) scheme. It is assumed that a linear minimum mean square estimator (LMMSE) is used for the channel estimation at the receiver. A simple and easy-to-evaluate asymptotical upper bound (AUB) of the symbol-error-rate (SER) is derived for uncoded AF cooperative communication systems with quadrature amplitude modulation (QAM) constellations. …
Automated detection of lung nodules in low-dose computed tomography
2007
A computer-aided detection (CAD) system for the identification of pulmonary nodules in low-dose multi-detector computed-tomography (CT) images has been developed in the framework of the MAGIC-5 Italian project. One of the main goals of this project is to build a distributed database of lung CT scans in order to enable automated image analysis through a data and cpu GRID infrastructure. The basic modules of our lung-CAD system, consisting in a 3D dot-enhancement filter for nodule detection and a neural classifier for false-positive finding reduction, are described. The system was designed and tested for both internal and sub-pleural nodules. The database used in this study consists of 17 low…
Seismic Performance of Earthquake-Resilient RC Frames Made with HSTC Beams and Friction Damper Devices
2021
Seismic behavior of RC frames with hybrid steel-trussed concrete beams is affected by panel zone damage due to a large amount of longitudinal reinforcement. Here the seismic efficiency of innovative frames characterized by friction damper devices (FDDs) at beam-to-column connections is compared against traditional frame. Three configurations are investigated: FDDs alone; FDDs with column-to-foundation connections having preloaded threaded bars and disk springs; FDDs with self-centering friction devices. Non-linear analyses show that FDDs alone prevent plastic hinge formation at beam ends and beam–column joint damage. FDDs with self-centering friction devices effectively limit both peak and …
Thermal properties in low dimensional structures below 1 K
2009
In this thesis thermal properties of low dimensional structures were experimentally studied at low temperatures with the help of tunnel junction thermometry and the Joule heating technique. The main objects of study were electron-phonon coupling in disordered thin metal films and phonon transport in suspended silicon nitride membranes. Our aim has been to clarify the effect of the phonon dimensionality, i.e. the effect of boundaries to the phonon modes and the transition from 3D to 2D phonons. The dimensionality cross over had not been observed before this work even though it is fabricationally a standard procedure to create the low dimensional environments for nanoscale applications and de…
1D ferrimagnetism in homometallic chains
1990
The magnetic properties of the cobalt zigzag chain Co(bpy)(NCS)2 (bpy=2,2′‐bipyridine) are discussed on the basis of an Ising‐chain model that takes into account alternating Landé factors. It is emphasized, for the first time, that a homometallic chain containing only one type of site can give rise to a 1D ferrimagneticlike behavior. Juan.J.Borras@uv.es , Eugenio.Coronado@uv.es