Search results for "Propagation"
showing 10 items of 676 documents
Performance Analysis of M-DPSK Modulation over Fast-Hoyt Fading Channels under Non-Isotropic Scattering Conditions
2021
In this paper, we analyze the symbol error probability (SEP) performance of M-ary differential phase shift keying (M-DPSK) modulation schemes over frequency-flat fast-varying Hoyt multipath fading channels. Assuming general non-isotropic scattering conditions, we first derive a finite-range integral expression for the probability density function (PDF) of the phase difference between two non-isotropic Hoyt vectors perturbed by additive white Gaussian noise (AWGN). Based upon the theory of M-DPSK modulation and the obtained PDF formula, the SEP of M-DPSK and its corresponding asymptotic behavior in non-isotropic fast-Hoyt fading channels are derived. Specifically, a double semi-finite range …
Reaction-diffusion on dynamic inhibition areas: A bio-inspired link scheduling algorithm
2014
We present the Dynamic Inhibition Areas Reaction-Diffusion (DIA-RD) algorithm, a distributed medium access control protocol that globally maximizes the spatial reusability (number of simultaneous transmissions per unit area) of wireless sensor networks. This algorithm is able, in consequence, to minimize the number of time slots needed to schedule the set of demanded links, making it very efficient to solve the Shortest Link Schedule problem. DIA-RD combines accurate interference management, provided by the use of dynamic inhibition areas based on the physical interference model; and global intelligent behavior, provided by the bio-inspired technique known as Reaction-Diffusion. This techni…
Functional design of power-split CVTs: An uncoupled hierarchical optimized model
2017
Abstract This paper provides a new model for the preliminary design of compound power-split CVTs. Unlike the existing models, the presented method allows the engineers to prioritize functionality and efficiency of the transmission, while delaying the choice of the involved gear sets’ layout as long as possible. The design approach follows a specific priority order, and each step deals with one particular issue, without mutual interference. A smart design-chart eases the assessment and the comparison of the only eligible alternatives, and eventually leads to a final feasible constructive scheme, which can be an excellent concept for further optimization and implementation. Moreover, the mode…
Multi-beam cooperative frequency reuse for coordinated multi-point transmission
2010
Coordinated multi-point (CoMP) joint transmission is considered in the 3rd generation partnership project (3GPP) long term evolution (LTE)-advanced as a key technique to mitigate inter-cell interference and improve the cell-edge performance. To effectively apply CoMP joint transmission, efficient frequency reuse schemes need to be designed to support resource management cooperation among coordinated cells. However, most of the existing frequency reuse schemes are not suitable for CoMP systems due to not considering multi-point joint transmission scenarios in their frequency reuse rules. In addition, the restrictions of frequency resources in those schemes result in a high blocking probabili…
Forecasting daily urban electric load profiles using artificial neural networks
2004
The paper illustrates a combined approach based on unsupervised and supervised neural networks for the electric energy demand forecasting of a suburban area with a prediction time of 24 h. A preventive classification of the historical load data is performed during the unsupervised stage by means of a Kohonen's self organizing map (SOM). The actual forecast is obtained using a two layered feed forward neural network, trained with the back propagation with momentum learning algorithm. In order to investigate the influence of climate variability on the electricity consumption, the neural network is trained using weather data (temperature, relative humidity, global solar radiation) along with h…
Exploiting the optical quadratic nonlinearity of zinc-blende semiconductors for guided-wave terahertz generation: A material comparison
2010
We present a detailed analysis and comparison of dielectric waveguides made of CdTe, GaP, GaAs and InP for modal phase matched optical difference frequency generation (DFG) in the terahertz domain. From the form of the DFG equations, we derived the definition of a very general figure of merit (FOM). In turn, this FOM enabled us to compare different configurations, by taking into account linear and nonlinear susceptibility dispersion, terahertz absorption, and a rigorous evaluation of the waveguide modes properties. The most efficient waveguides found with this procedure are predicted to approach the quantum efficiency limit with input optical power in the order of kWs.
Unknown order process emulation
2002
Approaches the emulation problem using feedforward neural networks of single input single output (SISO) processes, applying a backpropagation method with a higher convergence rate. In this kind of application, difficult problems appear when the system's order is a priori unknown. A search through the SISO processes space is proposed, aiming to find a favorable neural emulator over the training examples set.
ADC based measurements: Identification of the parameters for the uncertainty evaluation
2009
In the last years, many Authors have dealt with the uncertainty evaluation of the measurement performed by using an analog-to-digital converter, proposing different approach to analyze the uncertainty propagation. In all these studies, it is clearly pointed out that starting from the manufacturer specifications is the least expensive, the least time consuming and, often, the most accurate way to assess the uncertainties. However, the Authors, which have proposed methodologies for the uncertainty assessment, use different parameters as starting point. One of the main reasons which has caused this situation is the coexistent of various Standards concerning the characterization of the analog-t…
Ex vitro mycorrhization of vitro-derived plantlets of 'Carrizo' citrange [C. Sinensis (L.) Osb. × P. Trifoliata (L.) Raf.]
2015
In this study, vitro-derived plantlets of 'Carrizo' citrange were inoculated with Glomus intraradices during the acclimatization phase, from in vitro to in vivo. Plantlets were grown in presence (+M) and in absence of inoculum (-M) and in addition, in sterile and non-sterile substrate. After three months of culture, some vegetative parameters and the level of infection, varied greatly in the different theses. In particular, the highest formation of new branched roots has been observed in inoculated plantlets cultivated in sterile substrate. Good results were observed also in non-inoculated plantlets cultivated in non-sterile substrate, in presence of endemic inoculum. The same trend was obs…
The effects of benzyladenine and meta-Topolin on in vitro sprouting and regrowth after encapsulation of C35 citrange [Citrus sinensis (L.) Osb. × Pon…
2016
C35, a hybrid of ‘Ruby Blood’ sweet orange and trifoliate orange, is a promising Citrus rootstock, mainly due to its resistance to Citrus Tristeza Virus (CTV), one of the most serious pathology affecting citriculture. The use of resistant rootstocks, such as citranges, is an efficient tool to fight this plant disease. This implies a continuous increasing demand of resistant rootstocks, in order to carry out the turnover of sour orange, still the most used Citrus rootstock in Italy. Micropropagation, can provide innovative solutions to obtain, in a short time and in a small space, a number of plants higher than traditional propagation. Micropropagation efficiency is also affected by the cult…