Search results for "Threshold"
showing 10 items of 688 documents
Joint Optimization of Detection Threshold and Resource Allocation in Infrastructure-based Multi-band Cognitive Radio Networks
2012
[EN] Consider an infrastructure-based multi-band cognitive radio network (CRN) where secondary users (SUs) opportunistically access a set of sub-carriers when sensed as idle. The carrier sensing threshold which affects the access opportunities of SUs is conventionally regarded as static and treated independently from the resource allocation in the model. In this article, we study jointly the optimization of detection threshold and resource allocation with the goal of maximizing the total downlink capacity of SUs in such CRNs. The optimization problem is formulated considering three sets of variables, i.e., detection threshold, sub-carrier assignment and power allocation, with constraints on…
Signal Restoration via a Splitting Approach
2012
International audience; In the present study, a novel signal restoration method from noisy data samples is presented and is termed as "signal split (SSplit)" approach. The new method utilizes Stein unbiased risk estimate estimator to split the signal, the Lipschitz exponents to identify noise elements and a heuristic approach for the signal reconstruction. However, unlike many noise removal techniques, the present method works only in the non-orthogonal domain. Signal restoration was performed on each individual part by finding the best compromise between the data samples and the smoothing criteria. Statistical results are quite promising and suggest better performance than the conventional…
Experimental study on triangular central baffle flume
2019
Abstract In this paper the results of the experiments performed to study the flow through a Triangular Central Baffle Flume (TCBF) are reported. The investigated flume consists of a triangular baffle of the apex angle of 75° with a given base width. The theoretical stage-discharge formula was deduced by applying the Buckingham's Theorem and incomplete self-similarity hypothesis and was calibrated using the laboratory measurements carried out in this investigation. The proposed stage-discharge formula is characterized by a mean absolute relative error of 7.4% and 72% of the data points are in an error range of ±5%. The results indicate that TCBF flume is characterized by a flow capacity high…
Predicting rainfall erosivity by momentum and kinetic energy in Mediterranean environment
2018
Abstract Rainfall erosivity is an index that describes the power of rainfall to cause soil erosion and it is used around the world for assessing and predicting soil loss on agricultural lands. Erosivity can be represented in terms of both rainfall momentum and kinetic energy, both calculated per unit time and area. Contrasting results on the representativeness of these two variables are available: some authors stated that momentum and kinetic energy are practically interchangeable in soil loss estimation while other found that kinetic energy is the most suitable expression of rainfall erosivity. The direct and continuous measurements of momentum and kinetic energy by a disdrometer allow als…
Nonlinear conductance and heterogeneity of voltage-gated ion channels allow defining electrical surface domains in cell membranes
2015
Abstract The membrane potential of a cell measured by typical electrophysiological methods is only an average magnitude and experimental techniques allowing a more detailed mapping of the cell surface have shown the existence of spatial domains with locally different electric potentials and currents. Electrical potentials in non-neural cells are regulated by the nonlinear conductance of membrane ion channels. Voltage-gated potassium channels participate in cell hyperpolarization/depolarization processes and control the electrical signals over the cell surface, constituting good candidates to study basic biological questions on a more simplified scale than the complex cell membrane. These ch…
Spontaneous symmetry-breaking pathways: time-resolved study of agarose gelation
1996
Abstract Extensive time-resolved studies of self-assembly of agarose gels, performed with the use of a variety of techniques allowed identification of the initial break of symmetry and the actual path leading to self-assembly at concentrations well below the random percolation threshold. The overall process is seen to occur through the following sequence: (i) break of symmetry in the sol, causing the spontaneous generation of mesoscopic polymer-rich and solvent-rich regions; (ii) percolation, or nearly percolation [see (iv) below], of polymer-rich regions through the sample, still in the sol state; (iii) start of polymer cross-linking within polymer-rich regions; (iv) progress of cross-link…
Interfaces as design tools for the InAs/GaSb/InSb short-period superlattice for mid-infrared emission
2011
We use a standard 8 × 8 envelope-function approximation (EFA) formalism taking into account the effect of anisotropic and other interface (IF) interactions to investigate the electronic and optical properties of short-period superlattice laser structures (InAs/GaSb/InSb)×N grown on a GaSb substrate. We find that the band gaps numerically calculated at different temperatures give a good fitting with the experimental data confirming the model used. The calculated modal gain demonstrates that it is possible to achieve lasing operation at room temperature for N > 12 and for a reasonable total optical loss αt = 25 cm−1. Therefore, the 8 × 8 EFA formalism with IF design serves as a tool to model…
Identification of Synaptic Integration Mode in CA3 Pyramidal Neuron Model
2019
International audience; A morphologically realistic and anisotropic model of CA3 pyramidal neuron was developed to determine the synaptic integration modes the neuron is able to perform. Linearity and nonlinearity were identified in different synaptic locations with varying active mechanisms such as the presence of ionic channels in the dendritic arbor and the types of receptors in the synapse. Quantification of synaptic integration was performed using paired-pulse stimulation protocol and subthreshold input/output (sI/O) transformation. Results show that the mode of synaptic integration is location-dependent while the linearity or nonlinearity in the integration is mainly influenced by the…
Repetitive TMS temporarily alters brain diffusion
2004
The authors investigated whether repetitive transcranial magnetic stimulation (rTMS) at 1 Hz (12 minutes; 90% of motor threshold) to the primary motor cortex (M1) leads to changes in diffusion-weighted imaging (DWI). After the rTMS train, there was a temporary small restriction in diffusion within the targeted left M1 that disappeared after 5 minutes. These findings provide a physiologic correlate to the reported behavioral consequences of off-line 1-Hz rTMS and reveal the transitory nature of the effects.
P27-S Sex differences and cortical excitability in healthy adolescents
2019
Background Sex is known to influence brain development. However, sex differences in cortical excitability and their relationship to motor functions is unclear. Aim We examined the sex related differences in the degree of handedness, left and right motor cortex excitability and manual dexterity. Methods 28 healthy adolescents (age 16–19 years,19 girls) were studied. The degree of right-handedness was determined by the Waterloo Handedness Questionnaire. Motor threshold (MT) of the abductor pollicis brevis was measured on both hemispheres. Box and block test (BBT) was used for manual dexterity. Independent samples t-test was used in statistical analysis. Results There were no differences betwe…