Search results for " propagation"

Micropropagation of bay laurel (Daphne gnidiumL.)

1996

SummaryProcedures have been developed for the micropropagation of Daphne gnidium, a shrub species of ecological interest, using explants of juvenile and adult origin. Shoot proliferation rates were significantly affected by both salt formulation and benzylade- nine concentration. Best results were obtained on WP medium with 5 µM BA. The presence of indoleacetic acid in the induction medium improved BA-induced axillary bud proliferation from juvenile explants. Rooting of shoots produced in culture was difficult, especially those of adult origin. Besides an absolute requirement for auxin, calcium concentration and the pH of the medium affected the formation of adventitious roots from regenera…

1972

The determination of reactivity ratios is simplified by using an excess of one monomer (M1) at a time large enough that the copolymers will have a very small content of the other monomer (M2). In this case chain propagation takes place almost exclusively by addition to polymer radicals with a terminal M1-unit (P) and monomer consumption by propagation of P may be neglected. One reactivity ratio (r1) is obtained from monomer conversions by means of a simple integrated equation which is valid up to high conversions. A calculation is proposed in order to account for the neglected propagation via P. The other reactivity ratio (r2) is obtained from copolymerizations with excess M2. As the new me…

1973

The mechanism of radiation-induced polymerizations in the solid state has been a subject mostly open to speculation. As radiation usually generates several kinds of active species (radicals and ions) it is difficult to find out, which of these actually causes polymerization. We have developped a method distinguishing between cationic and anionic active centers. Cationic polymerizations are terminated by addition of a base such as sodium alkoxide in a suitable solvent. The alkoxide is incorporated into the polymer as an endgroup. This endgroup is determined analytically after isolation and purification of the polymer. The incorporation of alkoxy endgroups into the polymer is a proof of the o…

Efficient checking of coherence and propagation of imprecise probability assessments

2000

We consider the computational difficulties in the checking of coherence and propagation of imprecise probability assessments. We examine the linear structure of the random gain in betting criterion and we propose a general methodology which exploits suitable subsets of the set of values of the random gain. In this way the checking of coherence and propagation amount to examining linear systems with a reduced number of unknowns. We also illustrate an example.

FLUMO: FLexible Underwater MOdem

2019

The last years have seen a growing interest in underwater acoustic communications because of its applications in marine research, oceanography, marine commercial operations, the offshore oil industry and defense. High-speed communication in the underwater acoustic channel has been challenging because of limited bandwidth, extended multipath, refractive properties of the medium, severe fading, rapid time variation and large Doppler shifts. In this paper, we show an implementation of a flexible Software-Defined Acoustic (SDA) underwater modem, where modulation parameters are completely tunable to optimize performance. In particular, we develop the system architecture following two key ideas. …

Specific calibration and predictive uncertainty evaluation strategies for flood propagation models

2009

Hydraulic models are an essential tool in many fields, e.g. civil engineering, flood hazard and risk assessments, evaluation of flood control measures, etc. Nowadays there are many models of different complexity regarding the mathematical foundation and spatial dimensions available, and most of them are comparatively easy to operate due to sophisticated tools for model setup and control. However, the calibration of these models is still underdeveloped in contrast to other models like e.g. hydrological models or models used in ecosystem analysis. This has basically two reasons: First, the lack of relevant data against the models can be calibrated, because flood events are very rarely monitor…

Flow of turbulent superfluid helium inside a porous medium

2009

The work deals with further developments of a study previously initiated, in which a macroscopic model of inhomogeneous superfluid turbulence, based on extended thermodynamics, has been formulated. The model choose as fundamental fields, beside the traditional fields, two extra variables: the averaged vortex line length per unit volume and the heat flux. Using this model the propagation of the fourth sound inside a superleak is investigated: it is shown that, if the configuration of the vortex tangle inside the superleak are not altered -on the average- by the presence of the walls, when the fourth sound is propagated, vibrations in the vortex line density are present, too.

Optimization of Linearized Belief Propagation for Distributed Detection

2020

In this paper, we investigate distributed inference schemes, over binary-valued Markov random fields, which are realized by the belief propagation (BP) algorithm. We first show that a decision variable obtained by the BP algorithm in a network of distributed agents can be approximated by a linear fusion of all the local log-likelihood ratios. The proposed approach clarifies how the BP algorithm works, simplifies the statistical analysis of its behavior, and enables us to develop a performance optimization framework for the BP-based distributed inference systems. Next, we propose a blind learning-adaptation scheme to optimize the system performance when there is no information available a pr…

Modeling and Mitigating Errors in Belief Propagation for Distributed Detection

2021

We study the behavior of the belief-propagation (BP) algorithm affected by erroneous data exchange in a wireless sensor network (WSN). The WSN conducts a distributed multidimensional hypothesis test over binary random variables. The joint statistical behavior of the sensor observations is modeled by a Markov random field whose parameters are used to build the BP messages exchanged between the sensing nodes. Through linearization of the BP message-update rule, we analyze the behavior of the resulting erroneous decision variables and derive closed-form relationships that describe the impact of stochastic errors on the performance of the BP algorithm. We then develop a decentralized distribute…

Approach to equilibrium of a quarkonium in a quark-gluon plasma

2018

We derive equations of motion for the reduced density matrix of a heavy quarkonium in contact with a quark-gluon plasma in thermal equilibrium. These equations allow in particular a proper treatment of the regime when the temperature of the plasma is comparable to the binding energy of the quarkonium. These equations are used to study how the quarkonium approaches equilibrium with the plasma, and we discuss the corresponding entropy increase, or free energy decrease, depending on the temperature regime. The effect of collisions can be accounted for by the generalization of the imaginary potential introduced in previous studies, and from which collision rates are derived. An important outcom…