667 research outputs found
A proposito di uso politico della paura
No full textTra le tante declinazioni della paura, si può indicare quella dell'uso politico della paura, insinuata da chi governa nei governati o nei sudditi, al fine di ottenere consensi per introdurre o rafforzare riforme, che, per lo più, tendono a limitare i diritti dei governati. Un rituale che è seguito in molti momenti della storia italiana fin dalla fine del XIX secolo
Optimum space diversità detection of weak signals in non-Gaussain noise employing both time and spatial sampling
No full textPhobos. La paura in Omero e i 'maestri di paura' in Platone
No full textAttraverso un breve itinerario letterario e filosofico, questo saggio intende offrire uno scorcio sull’universo antico della paura per mostrare alcuni dei modelli omerici che hanno inciso su quel sistema tradizionale di credenze che Platone ridiscute criticamente. Omero descrive la paura nel contesto della guerra di Troia e ne analizza la fenomenologia fissando nell’immaginario l’idea che la fuga sia sinonimo di paura. Platone rilegge filosoficamente alcuni episodi letterari, mitici e storici per offrire una nuova prospettiva da cui guardare alla fuga ed educare alla paura
Selection diversity reception of multilevel NCFSK systems in impulsive noise environments
No full textSelection diversity reception of multilevel NCFSK systems in impulsive noise environments
No full textOptimum space diversità detection of weak signals in non-Gaussain noise employing both time and spatial sampling
No full textPaura e consenso politico
No full textL'articolo propone un'analisi del rapporto tra paura, immaginazione e formazione delle credenze, mettendo in relazione la riflessione di Thomas Hobbes con alcune teorie contemporanee sul ruolo del "framing" e delle "narrazioni" nell'intreccio tra comunicazione politica e news media
The Role of the Widely Linear Processing in the Narrowband and Wideband Systems
No full textIn this thesis, the role of the Widely-Linear processing in the narrowband and wideband systems has been proposed. With reference to narrowband systems, we analyzed the linear (L) constant modulus (CM) cost function under the general assumptions that improper modulation schemes of practical interest are employed. This study allows one to determine a broad family of undesired minima of the CM cost function, which do not lead to perfect symbol recovery in the absence of noise. Successively, we applied widely linear (WL) approach to the same context, providing the mathematical conditions assuring perfect symbol recovery in the absence of noise. Furthermore, we enlightened that, similarly to the L-CM equalizer, the performances of WL-CM equalizers suffer from the presence of undesired global minima. To overcome this drawback we proposed to resort to a constraint WL-CM equalizer. In the context of wideband systems, with reference to direct-sequence CDMA (DS-CDMA) technique, we developed a performance comparisons among ideal and data-estimated WL- and L-MOE (minimum output energy) receivers. As regard to the ideal implementation, we investigated the relative performances of the WL-MOE and L-MOE receivers in the high-SNR regime. In such a case, we provided a necessary and sufficient condition on the spreading codes, which allows the WL-MOE receiver to achieve perfect multiple access interference (MAI) suppression. As regard the data-estimated versions of the WL-MOE and L-MOE receivers, we derived easily interpretable formulas, which allow one to obtain clear insights about the effects of different parameters on performances. In addition, we have extended the previous analysis accounting for the effects of channel-estimation errors. Specifically, we presented a comprehensive performance comparison between different versions of the data-estimate L- and WL-MOE receivers with blind channel estimation. We derived easily interpretable formula that suggest that when considering finite sample-size implementation, the WL-MOE receiver with channel estimation is able to assure a significant performance gain (for low-to-moderate values of the SNR) with respect to its linear counterpart only when it is built by resorting to a more sophisticated implementation. In such a case, for a given channel length, it allows one to work with an increased number of users which makes it a viable choice in heavily-congested DS-CDMA networks. Finally, in the last part of this thesis, we addressed the problem of deriving mathematical conditions guaranteeing perfect symbol recovery in the absence of noise for either cyclic-prefix (CP) based or zero-padding (ZP) based multicarrier-CDMA (MC-CDMA) downlink transmissions, which employ frequency-domain symbol-spreading. The conditions derived are channel-independent and are expressed in terms of relatively simple system design constraints, regarding the maximum number of allowable users and their spreading sequences. Specifically, it was first shown that, similarly to a ZP-based MC-CDMA downlink, L-zero-forcing (ZF) can be guaranteed for a CP-based MC-CDMA downlink, even when the channel transfer function exhibits nulls on some used subcarriers. On the other hand, when the information-bearing symbols are improper, it was shown that, for both CP- and ZP-based systems, WL-ZF allows one to successfully operate even in overloaded scenarios, by doubling the system capacity, regardless of the channel zero locations. However, such an increased throughput can be achieved as long as appropriate complex-valued spreading codes are use
Energy Saving in QoS Fog-supported Data Centers
No full textOne of the most important challenges that cloud providers face in the explosive growth of data is to reduce the energy consumption of their designed, modern data centers. The majority of current research focuses on energy-efficient resources management in the infrastructure as a service (IaaS) model through "resources virtualization" - virtual machines and physical machines consolidation. However, actual virtualized data centers are not supporting communication–computing intensive real-time applications, big data stream computing (info-mobility applications, real-time video co-decoding). Indeed, imposing hard-limits on the overall per-job computing-plus-communication delays forces the overall networked computing infrastructure to quickly adopt its resource utilization to the (possibly, unpredictable and abrupt) time fluctuations of the offered workload.
Recently, Fog Computing centers are as promising commodities in Internet virtual computing platform that raising the energy consumption and making the critical issues on such platform. Therefore, it is expected to present some green solutions (i.e., support energy provisioning) that cover fog-supported delay-sensitive web applications. Moreover, the usage of traffic engineering-based methods dynamically keep up the number of active servers to match the current workload. Therefore, it is desirable to develop a flexible, reliable technological paradigm and resource allocation algorithm to pay attention the consumed energy. Furthermore, these algorithms could automatically adapt themselves to time-varying workloads, joint reconfiguration, and orchestration of the virtualized computing-plus-communication resources available at the computing nodes. Besides, these methods facilitate things devices to operate under real-time constraints on the allowed computing-plus-communication delay and service latency.
The purpose of this thesis is: i) to propose a novel technological paradigm, the Fog of Everything (FoE) paradigm, where we detail the main building blocks and services of the corresponding technological platform and protocol stack; ii) propose a dynamic and adaptive energy-aware algorithm that models and manages virtualized networked data centers Fog Nodes (FNs), to minimize the resulting networking-plus-computing average energy consumption; and, iii) propose a novel Software-as-a-Service (SaaS) Fog Computing platform to integrate the user applications over the FoE. The emerging utilization of SaaS Fog Computing centers as an Internet virtual computing commodity is to support delay-sensitive applications.
The main blocks of the virtualized Fog node, operating at the Middleware layer of the underlying protocol stack and comprises of: i) admission control of the offered input traffic; ii) balanced control and dispatching of the admitted workload; iii) dynamic reconfiguration and consolidation of the Dynamic Voltage and Frequency Scaling (DVFS)-enabled Virtual Machines (VMs) instantiated onto the parallel computing platform; and, iv) rate control of the traffic injected into the TCP/IP connection.
The salient features of this algorithm are that: i) it is adaptive and admits distributed scalable implementation; ii) it has the capacity to provide hard QoS guarantees, in terms of minimum/maximum instantaneous rate of the traffic delivered to the client, instantaneous goodput and total processing delay; and, iii) it explicitly accounts for the dynamic interaction between computing and networking resources in order to maximize the resulting energy efficiency. Actual performance of the proposed scheduler in the presence of: i) client mobility; ii) wireless fading; iii) reconfiguration and two-thresholds consolidation costs of the underlying networked computing platform; and, iv) abrupt changes of the transport quality of the available TCP/IP mobile connection, is numerically tested and compared to the corresponding ones of some state-of-the-art static schedulers, under both synthetically generated and measured real-world workload traces
Performance of a square-law combiner for reception of Nakagami fading orthogonal signals in Spherically invariant noise
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