Engine failures due to fatigue have cost the Air Force an estimated $400 million dollars per year over the past two decades. Damping treatments capable of reducing the internal stresses of fan and turbine blades to levels where fatigue is less likely to occur have the potential for reducing cost while enhancing reliability. This research evaluates the damping characteristics of magnesium aluminate spinel, MgO+Al2O3, (mag spinel) on titanium plates from an experimental point of view. The material and aspect ratio were chosen to approximate the low aspect ratio blades found in military gas turbine fans. In the past, work has generally been performed on cantilever supported beams, and thus the two-dimensional features of damping were lost. In this study plates were tested with a cantilevered boundary condition, using electrodynamic shaker excitation. The effective test area of each specimen was 4.5 in × 4.5 in. The nominal plate thickness was 0.125 in. Mag spinel was applied to both sides of the plate, at a thickness of 0.01 in, and damping tests were run at room temperature. The effect of the coating was evaluated at the 2nd bending mode (mode 3) and the chord wise bending mode (mode 4). A scanning laser vibrometer revealed the frequency and shape of each mode for the plates. Sine sweeps were used to characterize the damping of the coated and uncoated specimens for the modes tested. The coating increased damping nonlinearly for both modes tested in which the general outcome was similar to that found in beams.Nomenclature σ = stress E = Young's modulus ε = strain δ = displacement v = velocity ω = frequency (radians/sec) ζ = damping ratio ∆ω = bandwidth (ω 2 − ω 1 )
In this paper, a novel approach is introduced for classifying curves into proper families, according to their similarity. First, a mathematical quantity we call plane curvature is introduced and a number of propositions are stated and proved. Proper similarity measures of two curves are introduced and a subsequent statistical analysis is applied. First, the efficiency of the curve fitting process has been tested on 2 shapes datasets of reference. Next, the methodology has been applied to the very important problem of classifying 23 Byzantine codices and 46 Ancient inscriptions to their writers, thus achieving correct dating of their content. The inscriptions have been attributed to ten individual hands and the Byzantine codices to four writers.
The challenge of text-reuseMost of the texts of ancient Greek literature are irremediably lost and preserved only through quotations and text-reuses by later authors. In the last two centuries scholars have been looking for traces of lost authors and works in surviving texts and they have been producing many collections of fragmentary authors and works.1 Based on a Thesaurus Linguae Graecae (TLG) search, for the period between the eighth century BC and the third century CE inclusive, 59% of the authors are preserved only in fragments, 12% are known both from entirely preserved works and fragmentary ones, while 29% are represented by surviving works.2 Such percentages reveal the great shipwreck of Greek ancient texts and the challenge of working with innumerable pieces of information about lost authors and works that are randomly preserved in our textual tradition.The term fragment is the result of a long tradition of print editorial practices, where the contexts preserving traces of lost authors and works are extracted from their sources and reprinted in separate collections. Even if such editorial workflow has made an incomparable contribution to the reconstruction of the personalities of lost intellectuals, the concept of the textual fragment remains quite problematic and misleading. As a matter of fact, it includes a wide range of many different kinds of text-reuse and it always implies a certain degree of originality, which is very difficult to assess because the original text from which the reuse derives is always influenced and determined by the cover text, i.e. by the intention of the quoting author and the characteristics of the context where the text-reuse is preserved.
As edições digitais na área de clássicas têm surgido como aliadas no rompimento de barreiras e no enfrentamento de desafios no ensino das línguas e culturas clássicas. O objetivo deste artigo é destacar algumas características específicas de edições digitais das Letras Clássicas, como possíveis elementos de gênero na sua produção e sua leitura digitais, supondo serem uma forma de contribuir para a mobilização da aprendizagem das línguas clássicas e a formação docente na área. Descrevemos, de um lado, os componentes essenciais no processo de uma edição digital nova do texto grego do Édipo Rei, de Sófocles, preparado na Universidade Furman, para um curso de graduação. De outro, apontamos de que modo as anotações de edições digitais, em alinhamentos, treebanking e geoanotações, na qualidade de experiências de aprendizagem, são potenciais instrumentos de desenvolvimento.
We describe a hierarchical approach to modeling text that allows machine-actionable canonical citation of text at many levels of specificity. This model address the problem of overlapping or mutually exclusive analyses. In turn, this flexibility in citation allows rich linking of textual transcriptions and other data to regions-of-interest on digital images, of particular value to codicological and paleographic study. Our examples are from work on Byzantine manuscripts containing Greek epic poetry and scholarly commentary, but our approach can apply to any image-based project in documenting books, manuscripts, inscriptions or other text-bearing surfaces.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.