1,721,111 research outputs found
Geomorphologic and palynologic studies along the low course of the Adda River - The Pra'Marci section (Cremona, Italy)
No full textThe Holocene evolution of a Central Po Plain sector is reconstructed by means of geomorphological studies and pollen analyses on a peat horizon buried below fluvial sediments. The 14C age (5540 ± 190 y. B.P.) suggests that no large erosional phenomena along the main alpine rivers have occurred after the Atlantic climatic phase. Biostatic conditions are documented also by pollen spectra: the wood vegetation in the area was similar to the present potential forests (oak-hornbean mesophilous formations and alder hygrophilous formations). An important question is discussed about the beech presence, which is not included in the present potential vegetation of the Central Po Plain. This suggests more oceanic conditions in the late Atlantic bioclimate
Rinoceronte di Hundsheim, Stephanorhinus cf. S. hundsheimensis (Toula, 1902)
No full textSi descrivono i resti di rinoceronte rinvenuti nei depositi di Pianico-Seller
Le aree umide come archivi paleoambientali e archeologici tra tardiglaciale e Olocene antico: esempi e metodi di ricerca sul Cansiglio e al Palù di Livenza.
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On the design of structured stabilizers for lti systems
No full textDesigning a static state-feedback controller subject to structural constraint achieving asymptotic stability is a relevant problem with many applications, including network decentralized control, coordinated control, and sparse feedback design. Leveraging on the projection lemma, this letter presents a new solution to a class of state-feedback control problems, in which the controller is constrained to belong to a given linear space. We show through extensive discussion and numerical examples that our approach leads to several advantages with respect to existing methods: first, it is computationally efficient; second, it is less conservative than previous methods, since it relaxes the requirement of restricting the Lyapunov matrix to a block-diagonal form
Bayesian identification of distributed vector autoregressive processes
No full textThe identification of vector autoregressive (VAR) processes from partial samples is a relevant problem motivated by several applications in finance, econometrics, and networked systems (including social networks). The literature proposes several estimation algorithms, leveraging on the fact that these models can be interpreted as random Markov processes with covariance matrices satisfying Yule-Walker equations. In this paper, we address the problem of identification of distributed vector autoregressive (DVAR) processes from partial samples. The DVAR theory builds on the assumption that several processes are evolving in time, and the transition matrices of each process share some common characteristics. First, we discuss different models for describing the coupling among single processes. Subsequently, we propose an estimator for the transition matrices of the DVAR processes adopting an Empirical Bayes approach. More precisely, the local parameters are treated as random variables with a partially-unknown a priori density function, chosen as the conjugate family of distributions defined over symmetric, nonnegative-definite matrix-valued random variables and parameterized by suitable unknown hyperparameters. We develop an optimization algorithm to obtain the maximum likelihood estimates of the hyperparameters. The main feature of the proposed approach is that it does not require exact knowledge of the model describing the coupling between the different VAR processes, and it proves particularly well suited in scenarios in which the number of samples are allowed to be highly inhomogeneous or incomplete. The proposed techniques are validated on a numerical problem arising in social networks estimation
Paleoenvironmental dynamics in high alpine valleys: the correlation between landslide activity records and paleobotanical evidence.
No full textPrimula integrifolia L. sul crinale orobico: distribuzione, inquadramento autoecologico e sociologico.
No full textPollen analysis of marine sedimentary successions in the Etna region (E-Sicily, Italy) to evaluate the impact of volcanic explosive activity during the Holocene.
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