Optimal input cross-power spectra in shake table testing of asymmetric structures

The study considers earthquake shake table testing of bending-torsion coupled structures under multi-component stationary random earthquake excitations. An experimental procedure to arrive at the optimal excitation cross-power spectral density (psd) functions which maximize/minimize the steady state variance of a chosen response variable is proposed. These optimal functions are shown to be derivable in terms of a set of system frequency response functions which could be measured experimentally without necessitating an idealized mathematical model to be postulated for the structure under study. The relationship between these optimized cross-psd functions to the most favourable/least favourable angle of incidence of seismic waves on the structure is noted. The optimal functions are also shown to be system dependent, mathematically the sharpest, and correspond to neither fully correlated motions nor independent motions. The proposed experimental procedure is demonstrated through shake table studies on two laboratory scale building frame models.

The Feedback Capacity of the Binary Erasure Channel With a No-Consecutive-Ones Input Constraint

The input-constrained erasure channel with feedback is considered, where the binary input sequence contains no consecutive ones, i.e., it satisfies the (1, infinity)-RLL constraint. We derive the capacity for this setting, which can be expressed as C-is an element of = max(0 <= p <= 0.5) (1-is an element of) H-b (p)/1+(1-is an element of) p, where is an element of is the erasure probability and Hb(.) is the binary entropy function. Moreover, we prove that a priori knowledge of the erasure at the encoder does not increase the feedback capacity. The feedback capacity was calculated using an equivalent dynamic programming (DP) formulation with an optimal average-reward that is equal to the capacity. Furthermore, we obtained an optimal encoding procedure from the solution of the DP, leading to a capacity-achieving, zero-error coding scheme for our setting. DP is, thus, shown to be a tool not only for solving optimization problems, such as capacity calculation, but also for constructing optimal coding schemes. The derived capacity expression also serves as the only non-trivial upper bound known on the capacity of the input-constrained erasure channel without feedback, a problem that is still open.

Datas comemorativas

Apresenta as datas comemorativas do Brasil criadas por normas e também as datas costumeiras e populares.

Datas comemorativas e outras datas significativas

A publicação inaugura uma série comemorativa aos 190 anos da Independência do Brasil. Apresenta um levantamento das datas comemorativas e dos feriados nacionais que vigoram no território brasileiro. Estão elencadas principalmente aquelas instituídas por norma jurídica ou documentos oficiais. Inclui também, as datas comemoradas de modo costumeiro ou popular, apesar de haver divergências quanto à precisão das informações obtidas. Traz datas comemorativas instituídas na esfera internacional que buscam encorajar a cooperação entre governos e promover ações mundiais conjuntas voltadas para o bem-estar dos povos e do planeta. Estão incluídas ainda, as semanas comemorativas e as datas variáveis, que são aquelas comemoradas em dias não fixos. A pesquisa contemplou as datas comemorativas de maior significação e importância.