1,721,131 research outputs found
The metamorphoses of the EUR Water Tower, Rome, between autarchy and economic miracle (1940–59)
No full textIn a 1961 article, the engineer Roberto Colosimo Sr described his iconic water tower at EUR, Rome (1957–59, also known as ‘the mushroom’), recalling a previous 1940 project, unexecuted due to the entry of Italy into World War II. This paper analyses the transition between the two towers as a sort of animal metamorphosis, largely conditioned by the different scientific and cultural contexts. The first design maximized the strength through form-resistant structures. Its image would have evoked late antique architecture, in which firmness was entrusted to mass and geometry. The continuous and bold structures of the first solution, conceived during the autarchy imposed by the Fascist government, became more discrete in the 1957 project. The second solution, built in reinforced concrete, transformed the massive buttress of the autarchic design in punctual supports, intertwined in a stellar arrangement of shelves, which showed the high technological level and creative genius of post-war Italian engineering. The paper refers to archival documents to jointly study the two projects, revealing the metamorphoses that took place between two projects conceived for the same place and by the same author, but within different political and economic conditions
Intraprotocol fairness and interprotocol friendliness of TFRC congestion control algorithm
No full textThe TCP-friendly rate control (TFRC) algorithm has been proposed
for supporting applications such as video streaming or telephony over
the Internet, where a relative smooth sending rate is of importance.
The fairness and friendliness of TFRC over scenarios with multiple
congested routers is evaluated. Results obtained using the ns-2
simulator show that while TFRC improves network utilisation with
respect to Reno TCP, it exhibits a significant degree of unfairness and
unfriendliness towards Reno TCP
Object-oriented image analysis using the CNN Universal Machine: New analogic CNN algorithms for motion compensation, image synthesis and consistency observation
No full textVisual poetics: sight as a design tool in the drawings of Luigi Moretti
No full textThis chapter investigates the theory of visual perception applied by the Italian architect Luigi Moretti (1906-1973) to the analysis and design of architectural works. In particular, Moretti’s personal optical and perspective approach to design is explored through the analysis of his extraordinary drawings. Unlike the architectural drawings produced before or during his career, Moretti’s designs often show visual cones, and sometimes angles in numbers, in plan and section, which are also supported by written considerations on their role in the definition of the project
Channel Gain Lower Bound for IRS-Assisted UAV-Aided Communications
No full textThe Multiple-Input-Multiple-Output (MIMO) capabilities of an Intelligent Reflective Surface (IRS) combined with the inherent versatility of an Unmanned Aerial Vehicle (UAV) can significantly enhance the communication quality between a Ground User (GU) and a Base Station (BS). This work proposes a composite channel gain expression for performance analysis in IRS-assisted UAV-aided networks under Rician fading conditions. Differently from the present literature, the proposed formulation takes into account wave interference among surface elements and with the receiver. Moreover, Orthogonal Frequency Multiple Access (OFDMA) is employed to cope with spatial-and frequency-selective fading, enabling direct application in multi-user multi-drone scenarios. Numerical results demonstrate that the proposed model provides an underestimate, as expected from theoretical analysis, from which a lower bound for the data rate can be obtained, to be practically employed for system design and assessment
Quantum scheduling optimization for UAV-enabled IoT networks
No full textQuantum computing is a promising technology which is able to speed up computation, by several orders of magnitude, with respect to classical systems. In particular, quantum optimization can be employed to solve complex problems in many engineering fields. In this work, it is proposed to use Quantum Annealing (QA) to solve a binary optimization problem to derive an optimal scheduling plan in an Unmanned Aerial Vehicle (UAV)-enabled Internet of Things (IoT) network. Based on specific design criteria, specific problem formulation can be cast, thus providing real-time solutions
Using Combined Deterministic-Stochastic Average-Based-Spectra Approach in Operational Modal Analysis
No full textScheduling Channel Time Allocations in 802.15.3 WPANs for Supporting Multimedia Applications
No full textThe 802.15.3 standard is a reference point for high data-rate wireless personal area networks (WPANs), being able to support also multimedia applications with specific quality of service (QoS) requirements. In a 802.15.3 piconet, a single piconet co-ordinator (PNC) distributes channel time allocations (CTAs) to devices (DEVs) associated to it, in order to provide the expected QoS. The 802.15.3 standard does not specify how this allocation should be done. To bridge this gap, we propose a dynamic CTA scheduling scheme that provides bounded average delays to multimedia applications. The algorithm is based on a control theoretic approach and acts in two steps: (1) each single DEV computes its transmission needs by applying a control algorithm that targets empty transmission queues; (2) the PNC collects requests of DEVs and allocates CTAs by taking into account the capacity constraints of the wireless channel. The main properties and the tuning rules of the algorithm have been theoretically investigated. Moreover, in order to provide a comprehensive performance evaluation of the proposed approach, realistic scenarios with video, voice, and FTP flows have been simulated using ns-2. Results confirm that our scheduler is able to satisfy the expected delay bounds in a wide range of traffic loads
On optimizing drones' communications under different radio coverage conditions
No full textThe Internet of Drones (IoD) architecture is quickly gaining momentum thanks to its inherent ability to capitalize the pros of both Unmanned Aerial Vehicles (UAVs) and networking technologies. This work discusses a scenario involving a drone carrying out a surveying mission along a predefined path. With the aim of maximizing the gathered and transmitted high resolution video signals, a comparative study is proposed, encompassing two different radio coverage conditions. The resulting optimization problems are solved with different techniques: one of them is solved in closed-form expression, while the other one is approached using Linear Programming (LP). Simulation results are also presented to demonstrate the effectiveness of the proposed solutions
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