433 research outputs found
Nel Segno di Masaccio: L invenzione della prospettiva. (In the Traces of Masaccio. The Invention of Perspective.)
Exhibit revie
The Cambridge Companion to Piero della Francesca
Jeryldene M. Wood, ed. The Cambridge Companion to Piero della Francesca Cambridge: Cambridge University Press, 2002 Reviewed by JoĆ£o Pedro Xavie
Photogrammetric characterization of the scour cavity time evolution around a complex bridge pier
Design of Inverter Based CMOS Amplifiers in Deep Nanoscale Technologies
In this work, it is proposed a fully differential ring amplifier topology with a deadzone
voltage created by a CMOS resistor with a biasing circuit to increase the robustness over PVT
variations.
The study focuses on analyzing the performance of the ring amplifier over process,
temperature, and supply voltage variations, in order to guarantee a viable industrial employment
in a 7 nm FinFET CMOS technology node for being used as residue amplifier in ADCs.
A ring amplifier is a small modular amplifier, derived from a ring oscillator. It is simple
enough that it can quickly be designed using only a few inverters, capacitors, and switches. It can
amplify with rail-to-rail output swing, competently charge large capacitive loads using slew-based
charging, and scale well in performance according to process trends.
In typical process corner, a gain of 72 dB is achieved with a settling time of 150 ps.
Throughout the study, the proposed topology is compared with others presented in literature
showing better results over corners and presenting a faster response. The proposed topology isnāt
yet suitable for industry use, because it presents one corner significantly slower than the rest,
namely process corner FF 125 Ā°C, and process corner FS -40 Ā°C with a small oscillation
throughout the entire amplification period.
Nevertheless, it proved itself to be a promising technique, showing a high gain and a fast
settling without oscillation phase, with room for improvement.Neste trabalho, Ć© proposta uma topologia de ring amplifier com a deadzone a ser criada
atravĆ©s de uma resistĆŖncia CMOS com um circuito de polarizaĆ§Ć£o para aumentar a robustez para
as variaƧƵes PVT.
O estudo foca-se em analisar a performance do ring amplifier nas variaƧƵes de processo,
temperatura e tensĆ£o de alimentaĆ§Ć£o, de forma a garantir um uso viĆ”vel em indĆŗstria na tecnologia
de 7 nm FinFET CMOS, para ser usado como amplificador de resĆduo em ADCs.
Um ring amplifier Ć© um pequeno amplificador modular, derivado do ring oscillator. Ć
simples o suficiente para ser facilmente projetado usando apenas poucos inversores,
condensadores e interruptores. Consegue amplificar com rail-to-rail output swing, carregar
grandes cargas capacitivas com carregamento slew-based e escalar bem em termos de
performance de acordo com o processo.
No typical process corner, foi obtido um ganho de 72 dB com um tempo de estabilizaĆ§Ć£o
de 150 ps. Durante o estudo, a topologia proposta Ć© comparada com outras presentes na literatura
mostrando melhores resultados over corners e apresentando uma resposta mais rƔpida. A
topologia proposta ainda nĆ£o estĆ” preparada para uso industrial uma vez que apresenta um corner
significativamente mais lento que os restantes, nomeadamente, process corner FF 125 Ā°C, e outro
process corner, FS -40 Ā°C, com uma pequena oscilaĆ§Ć£o durante todo o perĆodo de amplificaĆ§Ć£o.
Todavia, provou ser uma tƩcnica promissora, apresentando um ganho elevado e uma rƔpida
estabilizaĆ§Ć£o sem fase de oscilaĆ§Ć£o, com espaƧo para melhoria
D-ADMM: A Communication-Efficient Distributed Algorithm For Separable Optimization
We propose a distributed algorithm, named Distributed Alternating Direction
Method of Multipliers (D-ADMM), for solving separable optimization problems in
networks of interconnected nodes or agents. In a separable optimization problem
there is a private cost function and a private constraint set at each node. The
goal is to minimize the sum of all the cost functions, constraining the
solution to be in the intersection of all the constraint sets. D-ADMM is proven
to converge when the network is bipartite or when all the functions are
strongly convex, although in practice, convergence is observed even when these
conditions are not met. We use D-ADMM to solve the following problems from
signal processing and control: average consensus, compressed sensing, and
support vector machines. Our simulations show that D-ADMM requires less
communications than state-of-the-art algorithms to achieve a given accuracy
level. Algorithms with low communication requirements are important, for
example, in sensor networks, where sensors are typically battery-operated and
communicating is the most energy consuming operation.Comment: To appear in IEEE Transactions on Signal Processin
Distributed Optimization With Local Domains: Applications in MPC and Network Flows
In this paper we consider a network with nodes, where each node has
exclusive access to a local cost function. Our contribution is a
communication-efficient distributed algorithm that finds a vector
minimizing the sum of all the functions. We make the additional assumption that
the functions have intersecting local domains, i.e., each function depends only
on some components of the variable. Consequently, each node is interested in
knowing only some components of , not the entire vector. This allows
for improvement in communication-efficiency. We apply our algorithm to model
predictive control (MPC) and to network flow problems and show, through
experiments on large networks, that our proposed algorithm requires less
communications to converge than prior algorithms.Comment: Submitted to IEEE Trans. Aut. Contro
Distributed Basis Pursuit
We propose a distributed algorithm for solving the optimization problem Basis
Pursuit (BP). BP finds the least L1-norm solution of the underdetermined linear
system Ax = b and is used, for example, in compressed sensing for
reconstruction. Our algorithm solves BP on a distributed platform such as a
sensor network, and is designed to minimize the communication between nodes.
The algorithm only requires the network to be connected, has no notion of a
central processing node, and no node has access to the entire matrix A at any
time. We consider two scenarios in which either the columns or the rows of A
are distributed among the compute nodes. Our algorithm, named D-ADMM, is a
decentralized implementation of the alternating direction method of
multipliers. We show through numerical simulation that our algorithm requires
considerably less communications between the nodes than the state-of-the-art
algorithms.Comment: Preprint of the journal version of the paper; IEEE Transactions on
Signal Processing, Vol. 60, Issue 4, April, 201
The Roman Villa in RabaƧal and Ćlvaro Siza
The residential area of the Roman villa in RabaƧal is a rare example of a house with an octagonal peristyle remarkable by its design coherence at all architectural levels, from the overall scale to decorative motifs. Everything is regulated by proportions derived from its octagonal plan naturally based in ad quadratum geometry. Recently, Siza was challenged to design covers and a visit tour in order to preserve this invaluable patrimony. Quite aware of the quality of the architecture displayed in this Roman villa he must have recognized in-situ many of his own architectural concerns. The sketchbook was opened, and the drawing search led him to propose two wood rectangular grid covers which, in spite of their modernity and technical sophistication, are still shapes with formal affinities with each part of the villa
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