MoMo: a group mobility model for future generation mobile wireless networks

Existing group mobility models were not designed to meet the requirements for accurate simulation of current and future short distance wireless networks scenarios, that need, in particular, accurate, up-to-date informa- tion on the position of each node in the network, combined with a simple and flexible approach to group mobility modeling. A new model for group mobility in wireless networks, named MoMo, is proposed in this paper, based on the combination of a memory-based individual mobility model with a flexible group behavior model. MoMo is capable of accurately describing all mobility scenarios, from individual mobility, in which nodes move inde- pendently one from the other, to tight group mobility, where mobility patterns of different nodes are strictly correlated. A new set of intrinsic properties for a mobility model is proposed and adopted in the analysis and comparison of MoMo with existing models. Next, MoMo is compared with existing group mobility models in a typical 5G network scenario, in which a set of mobile nodes cooperate in the realization of a distributed MIMO link. Results show that MoMo leads to accurate, robust and flexible modeling of mobility of groups of nodes in discrete event simulators, making it suitable for the performance evaluation of networking protocols and resource allocation algorithms in the wide range of network scenarios expected to characterize 5G networks.Comment: 25 pages, 17 figure

Consonant gemination in Italian: the affricate and fricative case

Consonant gemination in Italian affricates and fricatives was investigated, completing the overall study of gemination of Italian consonants. Results of the analysis of other consonant categories, i.e. stops, nasals, and liquids, showed that closure duration for stops and consonant duration for nasals and liquids, form the most salient acoustic cues to gemination. Frequency and energy domain parameters were not significantly affected by gemination in a systematic way for all consonant classes. Results on fricatives and affricates confirmed the above findings, i.e., that the primary acoustic correlate of gemination is durational in nature and corresponds to a lengthened consonant duration for fricative geminates and a lengthened closure duration for affricate geminates. An inverse correlation between consonant and pre-consonant vowel durations was present for both consonant categories, and also for both singleton and geminate word sets when considered separately. This effect was reinforced for combined sets, confirming the hypothesis that a durational compensation between different phonemes may serve to preserve rhythmical structures. Classification tests of single vs. geminate consonants using the durational acoustic cues as classification parameters confirmed their validity, and highlighted peculiarities of the two consonant classes. In particular, a relatively poor classification performance was observed for affricates, which led to refining the analysis by considering dental vs. non-dental affricates in two different sets. Results support the hypothesis that dental affricates, in Italian, may not appear in intervocalic position as singletons but only in their geminate form.Comment: Submitted to Speech Communication. arXiv admin note: substantial text overlap with arXiv:2005.0696

A Range-Normalization Model of Context-Dependent Choice: A New Model and Evidence

Most utility theories of choice assume that the introduction of an irrelevant option (called the decoy) to a choice set does not change the preference between existing options. On the contrary, a wealth of behavioral data demonstrates the dependence of preference on the decoy and on the context in which the options are presented. Nevertheless, neural mechanisms underlying context-dependent preference are poorly understood. In order to shed light on these mechanisms, we design and perform a novel experiment to measure within-subject decoy effects. We find within-subject decoy effects similar to what have been shown previously with between-subject designs. More importantly, we find that not only are the decoy effects correlated, pointing to similar underlying mechanisms, but also these effects increase with the distance of the decoy from the original options. To explain these observations, we construct a plausible neuronal model that can account for decoy effects based on the trial-by-trial adjustment of neural representations to the set of available options. This adjustment mechanism, which we call range normalization, occurs when the nervous system is required to represent different stimuli distinguishably, while being limited to using bounded neural activity. The proposed model captures our experimental observations and makes new predictions about the influence of the choice set size on the decoy effects, which are in contrast to previous models of context-dependent choice preference. Critically, unlike previous psychological models, the computational resource required by our range-normalization model does not increase exponentially as the set size increases. Our results show that context-dependent choice behavior, which is commonly perceived as an irrational response to the presence of irrelevant options, could be a natural consequence of the biophysical limits of neural representation in the brain

Progetto di un edificio commerciale a Latina: soluzioni strutturali ed energetiche

Questa tesi di laurea specialistica descrive le soluzioni adottate nella progettazione di tipo strutturale ed energetica di un fabbricato commerciale, di nuova costruzione sito nel comune di Latina, eseguita rispettando i vincoli imposti dalla normativa vigente in ciascun campo. La progettazione strutturale e quella energetica degli edifici, negli ultimi due anni, ha visto cambiare in modo radicale il quadro normativo, grazie all’emanazione di due norme che hanno portato notevoli cambiamenti rispetto al passato: le Nuove Norme Tecniche per le Costruzioni (NTC 2008) e le UNI 11300:2008-1/2/3/4. L’introduzione di queste due norme ha modificato il tipo di approccio alla progettazione in entrambi i campi, risultando queste ultime molto più severe e restrittive rispetto a quelle precedenti. Questa esigenza del legislatore è nata per far fronte alle nuove esigenze del Paese in termini di aumento della sicurezza strutturale degli edifici, soprattutto alla luce dei recenti eventi sismici verificatisi in Abruzzo, e di risparmio energetico, con l’obiettivo di sensibilizzare l’opinione pubblica ed i tecnici del settore a costruire edifici più efficienti energeticamente e nell’intento comune di ridurre l’utilizzo di petrolio a favore di energie alternative. L’esperienza progettuale svolta ha come obiettivo principale quello di interfacciarsi con queste nuove realtà progettuali, confrontandosi con due normative che, a due anni dall’entrata in vigore, sono tutt’ora soggette a modifiche e precisazioni. Il tutto tenendo presente la progettazione architettonica quale punto di partenza al quale si vanno ad affiancare ed integrare le soluzioni di carattere strutturale ed energetico ai fini di una corretta progettazione integrata dell’edificio

How choice reveals and shapes expected hedonic outcome

Humans tend to modify their attitudes to align with past action. For example, after choosing between similarly valued alternatives, people rate the selected option as better than they originally did, and the rejected option as worse. However, it is unknown whether these modifications in evaluation reflect an underlying change in the physiological representation of a stimulus' expected hedonic value and our emotional response to it. Here, we addressed this question by combining participants' estimations of the pleasure they will derive from future events, with brain imaging data recorded while they imagined those events, both before, and after, choosing between them. Participants rated the selected alternatives as better after the decision stage relative to before, whereas discarded alternatives were valued less. Our functional magnetic resonance imaging findings reveal that postchoice changes in preference are tracked in caudate nucleus activity. Specifically, the difference in blood oxygenation level-dependent (BOLD) signal associated with the selected and rejected stimuli was enhanced after a decision was taken, reflecting the choice that had just been made. This finding suggests that the physiological representation of a stimulus' expected hedonic value is altered by a commitment to it. Furthermore, before any revaluation induced by the decision process, our data show that BOLD signal in this same region reflects the choices we are likely to make at a later time

Uncertainty Principles and Balian-Low type Theorems in Principal Shift-Invariant Spaces

In this paper, we consider the time-frequency localization of the generator of a principal shift-invariant space on the real line which has additional shift-invariance. We prove that if a principal shift-invariant space on the real line is translation-invariant then any of its orthonormal (or Riesz) generators is non-integrable. However, for any $n\ge2$, there exist principal shift-invariant spaces on the real line that are also \nZ-invariant with an integrable orthonormal (or a Riesz) generator $\phi$, but $\phi$ satisfies $\int_{\mathbb R} |\phi(x)|^2 |x|^{1+\epsilon} dx=\infty$ for any $\epsilon>0$ and its Fourier transform $\hat\phi$ cannot decay as fast as $(1+|\xi|)^{-r}$ for any $r>1/2$. Examples are constructed to demonstrate that the above decay properties for the orthormal generator in the time domain and in the frequency domain are optimal