3,096 research outputs found
A Chemistry-Inspired Framework for Achieving Consensus in Wireless Sensor Networks
The aim of this paper is to show how simple interaction mechanisms, inspired
by chemical systems, can provide the basic tools to design and analyze a
mathematical model for achieving consensus in wireless sensor networks,
characterized by balanced directed graphs. The convergence and stability of the
model are first proven by using new mathematical tools, which are borrowed
directly from chemical theory, and then validated by means of simulation
results, for different network topologies and number of sensors. The underlying
chemical theory is also used to derive simple interaction rules that may
account for practical issues, such as the estimation of the number of neighbors
and the robustness against perturbations. Finally, the proposed chemical
solution is validated under real-world conditions by means of a four-node
hardware implementation where the exchange of information among nodes takes
place in a distributed manner (with no need for any admission control and
synchronism procedure), simply relying on the transmission of a pulse whose
rate is proportional to the state of each sensor.Comment: 12 pages, 10 figures, submitted to IEEE Sensors Journa
Numerical simulations of mountain winds in an alpine valley
The meteorological model WRF is used to investigate the wind circulation in Valle Camonica, Italy, an alpine valley that includes a large subalpine lake. The aim was to obtain the information necessary to evaluate the wind potential of this area and, from a methodological point of view, to suggest how numerical modeling can be used to locate the most interesting spots for wind exploitation. Two simulations are carried out in order to analyze typical scenarios occurring in the valley. In the first one, the diurnal cycle of thermally-induced winds generated by the heating-cooling of the mountain range encircling the valley is analyzed. The results show that the mountain slopes strongly affect the low-level winds during both daytime and nighttime, and that the correct setting of the lake temperature improves the quality of the meteorological fields provided by WRF significantly. The second simulation deals with an event of strong downslope winds caused by the passage of a cold front. Comparisons between simulated and measured wind speed, direction and air temperature are also shown
Dense bidisperse suspensions under non-homogenous shear
We study the rheological behaviour of bidisperse suspensions in three
dimensions under a non-uniform shear flow, made by the superimposition of a
linear shear and a sinusoidal disturbance. Our results show that i) only a
streamwise disturbance in the shear-plane alters the suspension dynamics by
substantially reducing the relative viscosity, ii) with the amplitude of the
disturbance determining a threshold value for the effect to kick-in and its
wavenumber controlling the amount of reduction and which of the two phases is
affected. We show that, iii) the rheological changes are caused by the
effective separation of the two phases, with the large or small particles
layering in separate regions. We provide a physical explanation of the phase
separation process and of the conditions necessary to trigger it. We test the
results in the whole flow curve, and we show that the mechanism remains
substantially unaltered, with the only difference being the nature of the
interactions between particles modified by the phase separation
Production cost model of the multi-jet-fusion technology
© IMechE 2019. The paper presents a model of the production costs of the multi-jet-fusion technology that is based on a model of production costs of the selective laser sintering technology. The model is developed using the methodology of analysis of the event-driven process chain, which consists of modeling, batch assembly, setup, building, removal, and blasting activities. Production costs of each of the activities are separated to direct (labor, material, and energy) costs and indirect (equipment, overheads, and other indirect) costs. The developed model represents a basis for the development of algorithms and software tools for the calculation of the production costs of the multi-jet-fusion technology, since it defines all the necessary inputs and calculation procedures that enable the calculation of the total costs of a batch of products. Besides, the paper presents a procedure for the estimation of production costs that are attributed to a single product or product type.The authors wish to acknowledge the support of European Commission through the project “Advanced design rules for optimal dynamic properties of additive manufacturing products – A_MADAM”, which has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No 734455
Characterization of DNA methylation as a function of biological complexity via dinucleotide inter-distances
We perform a statistical study of the distances between successive
occurrencies of a given dinucleotide in the DNA sequence for a number of
organisms of different complexity. Our analysis highlights peculiar features of
the dinucleotide CG distribution in mammalian DNA, pointing towards a
connection with the role of such dinucleotide in DNA methylation. While the CG
distributions of mammals exhibit exponential tails with comparable parameters,
the picture for the other organisms studied (e.g., fish, insects, bacteria and
viruses) is more heterogeneous, possibly because in these organisms DNA
methylation has different functional roles. Our analysis suggests that the
distribution of the distances between dinucleotides CG provides useful insights
in characterizing and classifying organisms in terms of methylation
functionalities.Comment: 13 pages, 5 figures. To be published in the Philosophical
Transactions A theme issue "DNA as information
Evoluzione con la distanza delle proprietà non termiche degli ammassi di galassie
Questo percorso di tesi affronta lo studio dell'emissione radio da parte di aloni presenti in ammassi di galassie - ossia le strutture massive più estese dell'Universo in equilibrio viriale - a diversi valori di redshift, per indagare se e come le proprietà degli ammassi si distinguano a seconda della diversa distanza da noi. E' stato considerato un campione di ammassi catalogati fino al 2018, integrando un campione precedente risalente al 2011, per un totale di 83 ammassi in fase di merger con aloni radio al centro. In termini della potenza radio, della luminosità in X e della massima dimensione lineare radio non si evince una netta separazione in funzione dei redshift; tuttavia, gli aloni radio a redshift maggiori di z=0.30 presentano valori di potenza, luminosità in X e dimensione tendenzialmente maggiori rispetto agli aloni a redshift minori di z=0.30. Un ulteriore allargamento del campione e il miglioramento della sensibilità degli strumenti di osservazione consentiranno una analisi statistica più approfondita e dettagliata
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