Multiscale Surrogate Modeling and Uncertainty Quantification for Periodic Composite Structures

Computational modeling of the structural behavior of continuous fiber composite materials often takes into account the periodicity of the underlying micro-structure. A well established method dealing with the structural behavior of periodic micro-structures is the so- called Asymptotic Expansion Homogenization (AEH). By considering a periodic perturbation of the material displacement, scale bridging functions, also referred to as elastic correctors, can be derived in order to connect the strains at the level of the macro-structure with micro- structural strains. For complicated inhomogeneous micro-structures, the derivation of such functions is usually performed by the numerical solution of a PDE problem - typically with the Finite Element Method. Moreover, when dealing with uncertain micro-structural geometry and material parameters, there is considerable uncertainty introduced in the actual stresses experienced by the materials. Due to the high computational cost of computing the elastic correctors, the choice of a pure Monte-Carlo approach for dealing with the inevitable material and geometric uncertainties is clearly computationally intractable. This problem is even more pronounced when the effect of damage in the micro-scale is considered, where re-evaluation of the micro-structural representative volume element is necessary for every occurring damage. The novelty in this paper is that a non-intrusive surrogate modeling approach is employed with the purpose of directly bridging the macro-scale behavior of the structure with the material behavior in the micro-scale, therefore reducing the number of costly evaluations of corrector functions, allowing for future developments on the incorporation of fatigue or static damage in the analysis of composite structural components.Comment: Appeared in UNCECOMP 201

Iron–sulfur clusters: from metals through mitochondria biogenesis to disease

Iron–sulfur clusters are ubiquitous inorganic co-factors that contribute to a wide range of cell pathways including the maintenance of DNA integrity, regulation of gene expression and protein translation, energy production, and antiviral response. Specifically, the iron–sulfur cluster biogenesis pathways include several proteins dedicated to the maturation of apoproteins in different cell compartments. Given the complexity of the biogenesis process itself, the iron–sulfur research area constitutes a very challenging and interesting field with still many unaddressed questions. Mutations or malfunctions affecting the iron–sulfur biogenesis machinery have been linked with an increasing amount of disorders such as Friedreich’s ataxia and various cardiomyopathies. This review aims to recap the recent discoveries both in the yeast and human iron–sulfur cluster arena, covering recent discoveries from chemistry to disease

Genetic factors affecting the response of skeletal muscle to strength training

The aim of this study was to investigate the influence of Angiotensin-I 3 Converting Enzyme (ACE) genotype and the influence of circulating ACE activity 4 on the extent of muscle growth and strength development achieved during 5 strength training. It was hypothesized that ACE Deletion (D) allele carriers would 6 have higher force output values before and after the 12 week strength training 7 programme. Forty male Caucasian recreationally active volunteers were 8 genotyped for ACE Insertion/Deletion (I/D) polymorphism, but only eighteen 9 subjects identified with the DD or the II genotype were qualified to participate. 10 Eleven II and seven DD subjects underwent a 12 week strength training program 11 for the quadriceps muscle group of the trained leg, with both legs assessed 12 weekly by isokinetic dynamometry at joint angles of 30°, 60° and 90°(isometric 13 knee extension) and 60°/sec and 180°/sec (isokinetic maximal torque). Biopsy 14 samples were obtained from the vastus lateralis of the trained leg pre- and post-15 training, and they were analyzed using light microscopy and computer-based 16 planimetry to identify the cross-sectional area of each major fiber type as an 17 index of hypertrophy. A number of histochemical staining methods (H&E, SDH, 18 GPDH, IHC, mATPases) were used for delineation of the fiber types. Circulating 19 ACE activity was determined in blood samples and DNA samples were extracted 20 from saliva for genotyping. ACE genotype was not associated with circulating 21 ACE activity, with DD individuals presenting similar plasma ACE activity levels 22 with II individuals (39.7 ± 40 and 40.5 ± 3.30 respectively, P = 0.89 pre-training, 23 41.9 ± 3.7 and 35.5 ± 4.30 respectively, P = 0.30 post-training). ACE activity did 24 not change significantly with training (40.2 ± 2.5 nmol His-Leu/min/mL pre-25 training, 38.1 ± 3 nmol His-Leu/min/mL post training, P = 0.41) and correlated 26 significantly with baseline isometric force of the untrained leg at 5° (r = 0.46, P 27 = 0.05) and isokinetic strength at 180°/sec (r = 0.52, P = 0.03). When strength 28 was presented as force production per kilogram of body mass, the above 29 correlations became non-significant. Isometric force at 60º post-training 30 revealed a significant effect of the genotype, in favour of the DD individuals, on 31 the trained leg F (1, 64) = 4.242, P = 0.04, observed power = 0.53, partial eta 32 squared = 0.062). The effect persisted after adjustment for weight, but when it 33 was adjusted for body mass index and physical activity (assessed by 34 questionnaires), the effect became non-significant (F (1, 63) = 3.13391, P = 0.08, 35 5 partial eta squared = 0.047, observed power = 0.41); and F (1, 63) = 3.1628, P = 1 0.08, partial eta squared = 0.048, observed power = 0.42, respectively).The 2 average cross-sectional area (AVECSA) of Type IIA fibres for the DD individuals 3 increased significantly post-training (4070 ± 506 μm² pre-training, 4674 ± 399 4 μm² post-training, t (6) = -2.999, P = 0.02) and so did the AVECSA of the Type I 5 fibers of II individuals (3345 ± 207 μm² pre-training, 3988 ± 239 μm² post-6 training, t (10) = -3.063, P = 0.01). The finding shows that the strength training 7 programme applied resulted in muscle hypertrophy, but the changes in AVECSA 8 were not genotype-related. In conclusion, our findings suggest a possible role for 9 ACE gene polymorphism in the regulation of human skeletal muscle strength, but 10 limited statistical power and confounding factors prevented us from drawing 11 clear conclusions

Control Shift

The legacy of industrialisation counts only a few decades of being accepted as cultural heritage. The change of perceptions over its connotation and significance, from a menace to historic landscapes to an outstanding historical resource, took place in an era of massive sociocultural and economic upheavals. Those far-reaching developments reshaped both the theory and the practice of heritage conservation. Since the 1970s, new conservation approaches started emerging and being employed, next to the long established strategies of preservation and restoration. Adaptive reuse was included in the repertoire of conservation and quickly gained ground, as a strategy which allowed both the preservation of heritage values and sustainable development. The incorporation of adaptive reuse as an alternative conservation approach marked a noteworthy shift in heritage care. Contemporary conservation seized aiming at the prevention of change. Instead, it embraced it, following the new axiom: ‘Managing change’. This dissertation, positioned in the crossroads of the heritage conservation, architectural and spatial planning fields, focuses on Industrial Heritage Reuse practice in Europe. Despite widely employed in the last half century, Industrial Heritage Reuse still remains particularly challenging and highly confusing, hiding internal and external risks. Those resonate from the conditions of present times, the ambiguities of the contemporary framework of conservation, the embedded dilemmas of the Reuse practice as well as from the particularities of this special heritage group. This vastly complex yet fascinating topic has not yet been studied holistically under the circumstances dictated by the contemporary era. A deeper and broader understanding of the practice has assumed greater urgency in the 21st century, as it is the stepping stone for the enhancement of the practice -a demand that is increasingly stressed by academic and professional circles. The aim of this dissertation is to explore the potential of enhancement of the Industrial Heritage Reuse through the identification and analysis of its influencing Aspects, under the light of the contemporary theoretical conservation concepts, the current demands of the field of practice and the rising challenges of the 21st century context. This research addresses a topical issue, drawing from the concepts of the contemporary theory of conservation, challenging outdated theoretical notions and conventional practical and methodological applications. Furthermore, it sheds light to a hazy and confusing subject, addressing the tensions and the unresolved issues, highlighted by the existing literature on multiple disciplines. It revisits and reinterprets the standing axiom ‘Managing Change’, providing the scientific community with missing answers on the way, the Actors and the criteria based on which this can be achieved. Drawing upon both theory and practice on an international level, this inquiry gives a holistic and multileveled view on the subject under investigation, stimulating further thought and debate. Apart from extending the academic body of knowledge, the intention of this doctoral research is also to become a useful springboard for the practitioners that engage with Industrial Heritage Reuse. In order to achieve that, this dissertation presents an international and retrospective review of Industrial Heritage care, allowing experience drawn from one country to inform approaches on safeguarding via Reuse on other countries. Furthermore, it offers inspiration and raises awareness through the ‘ReIH’ online knowledge platform (http://reindustrialheritage.eu/projects) and the analysis of twenty cases studies of best practice. Lastly, taking into account the pressing issues of sustainability, equality and multilateralism, it offers guidance, providing a much needed alternative framework for the conservation of Industrial Heritage. This framework is capable of practical implementation and can contribute to an enhanced, more responsive, more sustainable, more inclusive, more value-driven and more holistic practice

The discourse of mathematical ability: an archaeological approach

This article is an effort to understand and analyze the discourse of mathematical ability through an archaeological approach. We recognize and discuss the association between the discourse of mathematical ability and the three following discourses: standardizing as a means of effectiveness, the distinction between manual and intellectual labor and the “superiority” of mathematical engagement. Moreover, we distinguish between two forms of the discourse of mathematical ability: the biological determination of giftedness and the notion of ability within a meritocratic context. These discourses function as an obstacle in the formation of positive identities in relation to mathematics for students of certain backgrounds. We argue that the deconstruction of these discourses is a necessary condition for an equitable mathematics education

Δυναμικός Προγραμματισμός

Εθνικό Μετσόβιο Πολυτεχνείο--Μεταπτυχιακή Εργασία. Διεπιστημονικό-Διατμηματικό Πρόγραμμα Μεταπτυχιακών Σπουδών (Δ.Π.Μ.Σ.) “Εφαρμοσμένες Μαθηματικές Επιστήμες