Bibliografias temáticas / Degrade Structures

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Literatura científica selecionada sobre o tema "Degrade Structures"

Autor: Grafiati

Publicado: 8 de março de 2025

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Artigos de revistas sobre o assunto "Degrade Structures"

Kumari, Alka, Doongar R. Chaudhary e Bhavanath Jha. "Marine microbe with potential to adhere and degrade plastic structures". Canadian Journal of Biotechnology 1, Special Issue (5 de outubro de 2017): 130. http://dx.doi.org/10.24870/cjb.2017-a116.

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Fu, Yuhua, Ningxie Chen, Ziying Wang, Shouqing Luo, Yu Ding e Boxun Lu. "Degradation of lipid droplets by chimeric autophagy-tethering compounds". Cell Research 31, n.º 9 (8 de julho de 2021): 965–79. http://dx.doi.org/10.1038/s41422-021-00532-7.

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AbstractDegrading pathogenic proteins by degrader technologies such as PROTACs (proteolysis-targeting chimeras) provides promising therapeutic strategies, but selective degradation of non-protein pathogenic biomolecules has been challenging. Here, we demonstrate a novel strategy to degrade non-protein biomolecules by autophagy-tethering compounds (ATTECs), using lipid droplets (LDs) as an exemplar target. LDs are ubiquitous cellular structures storing lipids and could be degraded by autophagy. We hypothesized that compounds interacting with both the LDs and the key autophagosome protein LC3 may enhance autophagic degradation of LDs. We designed and synthesized such compounds by connecting LC3-binding molecules to LD-binding probes via a linker. These compounds were capable of clearing LDs almost completely and rescued LD-related phenotypes in cells and in two independent mouse models with hepatic lipidosis. We further confirmed that the mechanism of action of these compounds was mediated through LC3 and autophagic degradation. Our proof-of-concept study demonstrates the capability of degrading LDs by ATTECs. Conceptually, this strategy could be applied to other protein and non-protein targets.

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De Gasperi, R., S. al Daher, B. G. Winchester e C. D. Warren. "Substrate specificity of the bovine and feline neutral α-mannosidases". Biochemical Journal 286, n.º 1 (15 de agosto de 1992): 55–63. http://dx.doi.org/10.1042/bj2860055.

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Neutral alpha-mannosidases were prepared from bovine and cat liver. The activities were distinguished from lysosomal and Golgi alpha-mannosidases by their neutral pH optima, relatively low Km for their synthetic substrate p-nitrophenyl alpha-D-mannoside, inhibition by Zn2+ and absence of inhibition by Co2+, EDTA, low concentrations of swainsonine, or deoxymannojirimycin. The cytosolic alpha-mannosidases were not retained by concanavalin A-Sepharose. They were able to degrade efficiently a variety of oligosaccharides with structures corresponding to certain high-mannose glycans or the oligomannosyl parts of hybrid and complex glycans. However, unlike lysosomal alpha-mannosidases from the same species these enzymes were not able to degrade Man9GlcNAc2 efficiently, and the bovine neutral alpha-mannosidase was not able to degrade a hexasaccharide with a structure analogous to Man5GlcNAc2-PP-dolichol. Sharp differences were noted for the bovine and cat enzymes with regard to the specificity of degradation. The bovine neutral alpha-mannosidase degraded the substrates by defined pathways, but the cat neutral alpha-mannosidase often produced complex mixtures of products, especially from the larger oligosaccharides. Therefore the bovine enzyme resembled the rat and human cytosolic alpha-mannosidases, but the cat enzyme did not. The bovine and cat neutral alpha-mannosidases, unlike the corresponding lysosomal activities, did not show specificity for the hydrolysis of the (1----3)- and (1----6)-linked mannose residues in the N-linked glycan pentasaccharide core.

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Álvarez-Barragán, Joyce, Lilianha Domínguez-Malfavón, Martín Vargas-Suárez, Ricardo González-Hernández, Guillermo Aguilar-Osorio e Herminia Loza-Tavera. "Biodegradative Activities of Selected Environmental Fungi on a Polyester Polyurethane Varnish and Polyether Polyurethane Foams". Applied and Environmental Microbiology 82, n.º 17 (17 de junho de 2016): 5225–35. http://dx.doi.org/10.1128/aem.01344-16.

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ABSTRACTPolyurethane (PU) is widely used in many aspects of modern life because of its versatility and resistance. However, PU waste disposal generates large problems, since it is slowly degraded, there are limited recycling processes, and its destruction may generate toxic compounds. In this work, we isolated fungal strains able to grow in mineral medium with a polyester PU (PS-PU; Impranil DLN) or a polyether PU (PE-PU; Poly Lack) varnish as the only carbon source. Of the eight best Impranil-degrading strains, the six best degraders belonged to theCladosporium cladosporioidescomplex, including the speciesC. pseudocladosporioides,C. tenuissimum,C. asperulatum, andC. montecillanum, and the two others were identified asAspergillus fumigatusandPenicilliumchrysogenum. The best Impranil degrader,C. pseudocladosporioidesstrain T1.PL.1, degraded up to 87% after 14 days of incubation. Fourier transform infrared (FTIR) spectroscopy analysis of Impranil degradation by this strain showed a loss of carbonyl groups (1,729 cm−1) and N—H bonds (1,540 and 1,261 cm−1), and gas chromatography-mass spectrometry (GC-MS) analysis showed a decrease in ester compounds and increase in alcohols and hexane diisocyanate, indicating the hydrolysis of ester and urethane bonds. Extracellular esterase and low urease, but not protease activities were detected at 7 and 14 days of culture in Impranil. The best eight Impranil-degrading fungi were also able to degrade solid foams of the highly recalcitrant PE-PU type to different extents, with the highest levels generating up to 65% of dry-weight losses not previously reported. Scanning electron microscopy (SEM) analysis of fungus-treated foams showed melted and thinner cell wall structures than the non-fungus-treated ones, demonstrating fungal biodegradative action on PE-PU.IMPORTANCEPolyurethane waste disposal has become a serious problem. In this work, fungal strains able to efficiently degrade different types of polyurethanes are reported, and their biodegradative activity was studied by different experimental approaches. Varnish biodegradation analyses showed that fungi were able to break down the polymer in some of their precursors, offering the possibility that they may be recovered and used for new polyurethane synthesis. Also, the levels of degradation of solid polyether polyurethane foams reported in this work have never been observed previously. Isolation of efficient polyurethane-degrading microorganisms and delving into the mechanisms they used to degrade the polymer provide the basis for the development of biotechnological processes for polyurethane biodegradation and recycling.

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Cao, Xian, Feng Gu, Hui Wang, Zhou Fang e Xian-ning Li. "The degradation of azo dye with different cathode and anode structures in biofilm electrode reactors". RSC Advances 7, n.º 27 (2017): 16854–60. http://dx.doi.org/10.1039/c7ra00108h.

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Wang, Jiawei, Guanhua Zhang, Jinliang Liu e Yanmin Jia. "Research on destructive test of pretensioning prestressed concrete hollow slab in service". International Journal of Structural Integrity 9, n.º 4 (13 de agosto de 2018): 429–41. http://dx.doi.org/10.1108/ijsi-07-2017-0043.

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Purpose During service period, the bridge structures will be affected by the environment and load, so the carrying capacity will decline. The purpose of this paper is to research on the bearing capacity of bridge structures with time. Design/methodology/approach Destructive test and non-linear finite element analysis are carried out by utilizing two pretensioning prestressed concrete hollow slabs in service for 20 years; using the structural test deflection value to simulate the stiffness degradation of the service bridge and the finite element calculation results verify the accuracy of the calculation. Findings The flexural rigidity of the main beam when the test beam is destructed is degraded to approximately 20 percent of that before the test, which agrees well with the result of finite element analysis and indicates that the method of deducing the flexural rigidity of the structure according to the measured deflection value can effectively simulate the rigidity degradation law of the bridge in service. The crack resistance property of the test beam degrades obviously and the ultimate bearing capacity of the bending resistance does not degrade obviously. Originality/value The research results truly reflect the destruction process, destructive form, bearing capacity and rigidity degradation law of the old beam of the concrete bridge in service for 20 years and can provide technical basis for optimization design of newly built bridges of the same type and maintenance and reinforcement design of existing old bridges.

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Xiao, Mei-Sheng, e Jeremy E. Wilusz. "An improved method for circular RNA purification using RNase R that efficiently removes linear RNAs containing G-quadruplexes or structured 3′ ends". Nucleic Acids Research 47, n.º 16 (3 de julho de 2019): 8755–69. http://dx.doi.org/10.1093/nar/gkz576.

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AbstractThousands of eukaryotic protein-coding genes generate circular RNAs that have covalently linked ends and are resistant to degradation by exonucleases. To prove their circularity as well as biochemically enrich these transcripts, it has become standard in the field to use the 3′-5′ exonuclease RNase R. Here, we demonstrate that standard protocols involving RNase R can fail to digest >20% of all highly expressed linear RNAs, but these shortcomings can largely be overcome. RNAs with highly structured 3′ ends, including snRNAs and histone mRNAs, are naturally resistant to RNase R, but can be efficiently degraded once a poly(A) tail has been added to their ends. In addition, RNase R stalls in the body of many polyadenylated mRNAs, especially at G-rich sequences that have been previously annotated as G-quadruplex (G4) structures. Upon replacing K+ (which stabilizes G4s) with Li+ in the reaction buffer, we find that RNase R is now able to proceed through these sequences and fully degrade the mRNAs in their entirety. In total, our results provide important improvements to the current methods used to isolate circular RNAs as well as a way to reveal RNA structures that may naturally inhibit degradation by cellular exonucleases.

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Deschamps, A. M. "Évaluation de la dégradation de deux types de tanin condensé par des bactéries isolées d'écorces en décomposition". Canadian Journal of Microbiology 31, n.º 5 (1 de maio de 1985): 499–502. http://dx.doi.org/10.1139/m85-092.

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Forty-eight bacterial strains isolated from decaying bark were cultivated in a mineral medium with added quebracho and mimosa tannin extracts as carbon sources. The degradation of the two condensed tannins by each bacterial strain was compared by means of two dosage methods permitting estimations of the astringent capacity losses and the attack of the flavane-3-ols groups. For an even incubation period, tannin from mimosa was more strongly degraded than that from quebracho, and depolymerization was much more important than the attack of monomeric structures. These results confirmed the aptitude of those bacteria to degrade condensed tannins, and thus practical utilisation can be foreseen for such strains.[Translated by the journal]

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Jing, Yanqiu, Qiang Lei, Chun Xia, Yu Guan, Yide Yang, Jixian He, Yang Yang, Yonghui Zhang e Min Yan. "Synthesis of Ag and AgCl co-doped ZIF-8 hybrid photocatalysts with enhanced photocatalytic activity through a synergistic effect". RSC Advances 10, n.º 2 (2020): 698–704. http://dx.doi.org/10.1039/c9ra10100d.

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Recently, Ag/AgCl composites with different structures have been widely studied and used as photocatalysts to degrade dye pollutants, due to their high separation efficiency of electron–hole pairs under visible light irradiation.

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Xiao, Zi Jun, Rui Qian Qi, Fang Fang Huo, Yun Ling Huang, Hai Xu e Jian R. Lu. "Co-Biodegradation of Multiple Monocyclic Phenolic Compounds by a Novel 2,3-Xylenol-Degrading Pseudomonas Isolate". Advanced Materials Research 354-355 (outubro de 2011): 1329–32. http://dx.doi.org/10.4028/www.scientific.net/amr.354-355.1329.

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Monocyclic phenolic compounds (MCPCs) from petroleum and coal sources mainly include phenol, cresols, and xylenols. A newly isolated 2,3-xylenol-degrading strain,Pseudomonassp. XQ23, was found to be capable of degrading up to 10 MCPCs for the first time. Addition of easy-to-degrade MCPCs such as phenol and cresols helped decompose hard-to-degrade xylenols and the sequential digestion of the phenolic substrates was highly dependent on their molecule structures. The action on multiple MCPCs by the new isolate XQ23 from this work revealed useful clues on the co-biodegradation of multiple pollutants.

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Mais fontes

Teses / dissertações sobre o assunto "Degrade Structures"

Zoll, Sebastian [Verfasser], e Thilo [Akademischer Betreuer] Stehle. "Crystal structures of the major staphylococcal Autolysin E : How autolysins recognize and degrade the Gram-positive cell wall / Sebastian Zoll ; Betreuer: Thilo Stehle". Tübingen : Universitätsbibliothek Tübingen, 2012. http://d-nb.info/1162699825/34.

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Medina, Mordan Victor Randy. "Développement des courbes de vulnérabilité probabiliste des structures dégradées soumises aux actions sismiques". Electronic Thesis or Diss., Normandie, 2024. http://www.theses.fr/2024NORMIR36.

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L’analyse de vulnérabilité sismique est essentielle en ingénierie pour évaluer la sensibilité des structures aux séismes, permettant ainsi de réduire les risques en identifiant les faiblesses des infrastructures. Facteurs tels que les conditions du sol et la dégradation des matériaux influencent la réponse structurelle, accentuant la vulnérabilité face aux événements sismiques. L’analyse de vulnérabilité, appliquée à des structures individuelles ou à des zones urbaines, informe les pratiques de conception, l’aménagement du territoire et les politiques de gestion des risques. Les infrastructures critiques, comme les hôpitaux et les barrages, nécessitent une évaluation rigoureuse pour garantir leur résilience pendant et après les séismes. Dans le chapitre 2, l'analyse statique non linéaire (NSA) est explorée pour simuler la réponse des structures aux forces sismiques. La NSA, par sa simplicité computationnelle, génère des courbes de capacité révélant les déformations inélastiques et la résistance résiduelle, facilitant ainsi les évaluations de performance. Ce chapitre met également en évidence l'importance de la flexibilité du sol et de la corrosion. Le modèle de Winkler est utilisé pour simuler l'interaction sol-structure, montrant comment les sols plus mous amplifient les déformations et augmentent la vulnérabilité sismique. Un modèle de corrosion uniforme démontre que la dégradation réduit la capacité des structures, rendant nécessaire la prise en compte de ces facteurs dans l’évaluation de la fragilité. Le chapitre 3 propose les modèles de substitution comme alternative aux simulations de Monte Carlo pour développer des courbes de fragilité. Ces courbes estiment la probabilité d’atteindre un état de dommage en fonction de l'intensité sismique, mais les méthodes traditionnelles sont coûteuses en calculs. Le modèle PC-Kriging (PCK), présenté dans ce chapitre, capte efficacement les événements rares, combinant l’expansion en chaos polynomial et le Kriging pour une représentation détaillée des réponses structurelles. Cette méthodologie optimise le temps de calcul, rendant l’évaluation de la fragilité plus accessible dans des contextes d’évaluation de risques. Le chapitre 4 approfondit l’évaluation de la fragilité sismique en intégrant la relation structure-sol et la corrosion. L’inclusion de ces facteurs complexes, souvent négligés, permet une représentation réaliste des comportements structurels. La méthodologie de substitution active, notamment le modèle PCK, permet d’intégrer ces paramètres sans coûts prohibitifs, offrant une vue plus complète de la vulnérabilité. Par exemple, dans des sols mous, la probabilité d’échec augmente, surtout sous des séismes de faible intensité fréquents. Cette avancée méthodologique assure des évaluations de fragilité précises et soutient une prise de décision en ingénierie sismique. En conclusion, cette recherche représente une contribution majeure à l’évaluation de la fragilité sismique, démontrant l’importance de la flexibilité du sol et de la corrosion. Les modèles de substitution offrent une approche efficace et précise, optimisant les ressources de conception et de maintenance pour renforcer la résilience des infrastructures face aux séismes. Cette thèse doctorale met en lumière le rôle fondamental de l'interaction sol-structure et de la corrosion, remettant en question l’hypothèse conventionnelle de base fixe et offrant une perspective intégrée sur la sécurité des structures dans les zones sismiques
Seismic fragility analysis is essential in engineering to assess structural responses to earthquakes, helping reduce infrastructure vulnerability by identifying weaknesses and environmental factors, like soil conditions and material degradation, which impact immediate and long-term resilience. Fragility analysis provides a comprehensive framework, applicable from individual buildings to urban zones, guiding design and risk management strategies. Chapter 2 introduces nonlinear static analysis (NSA) to evaluate structural behavior under seismic loads, generating capacity curves that represent structures' ability to withstand seismic forces. Additionally, the chapter addresses critical factors like soil-structure interaction and corrosion degradation. Using the Winkler model, soil flexibility is simulated, showing how softer soils amplify seismic deformations. A uniform corrosion model reveals that degradation reduces structural stiffness, emphasizing the need to include both factors in fragility evaluations. Chapter 3 explores surrogate models as an alternative to Monte Carlo simulations for generating fragility curves, which estimate the likelihood of specific damage states based on seismic intensity. The PC-Kriging (PCK) model accurately and efficiently captures rare events, combining polynomial chaos expansion with Kriging, making it well-suited for practical applications. Chapter 4 presents an advanced approach to seismic fragility by integrating soil-structure interaction and corrosion. These factors, traditionally omitted, offer a more realistic view of structural responses under seismic loads. The PCK model enables detailed and computationally feasible assessments of various seismic and degradation scenarios, overcoming limitations of conventional methods. In conclusion, this research enhances seismic fragility assessment by combining nonlinear modeling, degradation factors, and computational efficiency through surrogate models. The study highlights the importance of soil flexibility and corrosion in evaluations. This methodology enables precise, practical assessments, optimizing design and maintenance resources, thereby boosting structural resilience to earthquakes

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Durrant, Benedict Richard Fabian. "The meet property in local degree structures". Thesis, University of Leeds, 2014. http://etheses.whiterose.ac.uk/7548/.

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In this thesis we look at whether two different classes of local Turing degrees (the c.e. degrees, and the 1-generic degrees below 0') satisfy the meet property - where a degree a satisfies the meet property if it is incomputable and for all b < a there exists a non-zero degree c such that a ∧ c = 0. We first give a general discussion of the Turing Degrees and certain known results, before giving a brief introduction to priority arguments. This is followed by some more technical considerations (full approximation and minimal degree constructions) before the proof of two new theorems - the first concerning c.e. degrees and the meet property and the second concerning 1 − generic degrees and the meet property. Chapter 1 contains a broad introduction to the Turing Degrees, and Chapter 2 to the Local Degrees. In Chapter 3 we consider minimal degree constructions, which we use in Chapter 4 to prove our first new theorem - Theorem 4.2.1 Given any non-zero c.e. degree a and any degree b < a, there is a minimal degree m < a such that m ≰ b. From which we get Corollary 4.2.2 Every c.e. degree satisfies the meet property - answering a question first asked by Cooper and Epstein in the 1980s. In Chapter 5 we prove the second new theorem - Theorem 5.2.2 There exists a 1 − generic degree which does not satisfy the meet property - showing that a result from Kumabe in the 1990s does not extend to the case n = 1.

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Tann, David Bohua. "Retrofitting of mechanically degraded concrete structures using fibre reinforced polymer composites". Thesis, University of South Wales, 2001. https://pure.southwales.ac.uk/en/studentthesis/retrofitting-of-mechanically-degraded-concrete-structures-using-fibre-reinforced-polymer-composites(efce1110-34e1-457d-8ec5-3ef5da026018).html.

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This research involves the study of the short term loaded behaviour of mechanically degraded reinforced concrete (RC) flexural elements, which are strengthened with fibre reinforced polymer (FRP) composites. The two main objectives have been: (a) to conduct a series of realistic tests, the results of which would be used to establish the design criteria, and (b) to carry out analytical modelling and hence develop a set of suitable design equations. It is expected that this work will contribute towards the establishment of definitive design guidelines for the strengthening of reinforced concrete structures using advanced fibre composites. The experimental study concentrated on the laboratory testing of 30 simply supported, and 4 two-span continuous full size RC beams, which were strengthened by either FRP plates or fabric sheets. The failure modes of these beams, at ultimate limit state, were examined and the influencing factors were identified. A premature and extremely brittle collapse mechanism was found to be the predominant type of failure for beams strengthened with a large area of FRP composites. A modified semi-empirical approach was presented for predicting the failure load of such over strengthened beams. Despite the lack of ductility in fibre composites, it was found that the FRP strengthened members would exhibit acceptable ductile characteristics, if they were designed to be under strengthened. A new design-based methodology for quantifying the deformability of FRP strengthened elements was proposed, and its difference to the conventional concept of ductility was discussed. The available techniques for ductility evaluation of FRP strengthened concrete members were reviewed and a suitable method was recommended for determining ductility level of FRP strengthened members. A non-linear material based analytical model was developed to simulate the flexural behaviour of the strengthened and control beams, the results were seen to match very well. The parametric study provided an insight into the effects of various factors including the mechanical properties and cross sectional area of FRP composites, on the failure modes and ductility characteristics of the strengthened beams. Based on the findings of the experimental and analytical studies, design equations in the BS 8110 format were developed, and design case studies have been carried out. It was concluded that fibre composites could effectively and safely strengthen mechanically degraded reinforced concrete structures if appropriately designed. The modes of failure and the degree of performance enhancement of FRP strengthened beams depend largely on the composite material properties as well as the original strength and stiffness of the RC structure. If the FRP strengthened elements were designed to be under-strengthened, then the premature and brittle failure mode could be prevented and ductile failure mode could be achieved. It was also found that existing steel reinforcement would always yield before the FRP composite reached the ultimate strength. Furthermore, a critical reinforcement ratio, above which FRP strengthening should not be carried out, was defined. It was concluded that FRP strengthening is most suitable for reinforced concrete floor slabs, bridge decks, flanged beams and other relatively lightly reinforced elements. The study also revealed that to avoid a brittle concrete failure, existing doubly reinforced members should not be strengthened by FRP composites.

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He, Mingzhe. "Insight into galloping instability of a multi-degree-of-freedom slender structure with structural and aerodynamic couplings". Thesis, University of Bristol, 2016. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.705480.

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FADDA, MARIA LUISA. "Giudizio immediato sullo stato di degrado dei ponti in c.a. basato su indagini low-cost". Doctoral thesis, Università degli Studi di Cagliari, 2016. http://hdl.handle.net/11584/266696.

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The structural engineer is often involved to express an opinion on the state of efficiency of the existing structures. This is partly because, in Italy, a large part of structures was built before the middle of the last century. Indeed, the 14th General Census of Population and Housing in 2001, released by Istat, that counted 12.774.131 buildings and 38.397 building complexes, for a total of 12.812.528 units, shows that 19,2% (2.150.259) was built before 1919, 12,3% between 1919 and 1945, 50,0% between 1946 and 1981; 11,5% from 1982 to 1991 and 7,0% since 1991. In addition to building, the field of road infrastructure requires as well special attention. In recent years the efficiency of infrastructure has been questioned due to various phenomena such as the increase in traffic loads, increasing the speed of travel, the changes of the relevant legislation relating to safety standards. The functionality of the bridges depends closely on a good inspection activities, and the lack of a proper and timely maintenance, entails an increase of the deterioration and therefore higher costs of repair. The periodic assessment of the conditions of stability of infrastructures is part of the duties of the company and Agencies owners of the roads. They are therefore directly responsible for any damage suffered by road users in dependence of instability or collapse of the bridges. There is therefore the need to assess the reliability of the infrastructure, with particular attention to those who, although they have far exceeded their threshold of useful life, are still in operation. In recent years, many companies of management of road networks have turned their interest to the definition of systems of Bridge Management System (BMS). BMS is the set of inspection, investigation, maintenance, repair of a group of bridges, organized according to priority, with the support of computer databases and algorithms officers. The state of conservation is characterized by assigning qualitative judgments. Some BMS provide for the detection of the extension and intensity of the defects, others associate to each element a qualitative index relative to the condition in which is each element. The bibliographic study, showed that no existing method considers the location of the damage within the element in which it manifests itself, although it a fundamental parameter for a correct diagnosis as closely related to the kinematic mechanism of collapse. The goal of my research work has been to provide a useful decision support tool during the data analysis of inspection, identifying a mode of low-cost and immediate investigation, for concrete bridges, which achieves a reliable judgment on the static condition of the structure inspected. It has been given special attention to concrete structures, the most widely used material in the field of civil construction. Forty years ago, it was presented as a material with low maintenance and almost unlimited duration. Quite different is the situation that presents itself today to the industry, it is remarkable the presence in Italy of reinforced concrete structures subjected to situations of instability for which you need to make thorough checks to assess their strength. The process that we propose is based: on visual observation of the bridge and on the analysis of the data obtained by means of instrumental tests carried out on the material to be inspected. Assuming that to do a good structural diagnosis, we must find the right compromise between reliability and invasiveness, it has been chosen, as a primary investigation, non-destructive tests, ie the complex of tests and surveys that do not alter the material and do not require the destruction of the structure. In particular, among the various non-destructive techniques, I chose to use the rebound hammer and ultrasonic testing techniques. In order to verify the reliability of non-destructive testing, it has been arranged a campaign of experimental investigation of a series of mixtures, packaged with concrete class different to be able to evaluate a wide range of resistances. They were made a total of 100 cubic test pieces of side 15 cm. They were then subjected to non-destructive tests for the measurement of the ultrasonic velocity and the rebound number, and in the end they were subjected to a breaking test for the determination of the compressive strength. It was then studied the correlation between the non-destructive testing and compression testing. The classical approach for the study of the correlation is to calibrate the regression lines between the indirect properties and the material characteristics and constructional of interest. The proposed methodology is based instead on the use of neural networks, which is a simple and quick tool of correlation between the measured and the mechanical properties of the material. From this practical application it has been identified neural networks as a way to better predict the value of concrete strength investigated, starting from the use of the results obtained by the low-invasive investigations. The proposed method of assessment can be summarized into two steps: • Visual inspection: identification and classification of any degradations and failures on the structure, it must be targeted to the identification of critical points that present and guide the subsequent phases of diagnostic. During the visual inspection is to be assessed the condition of each structural element, identifying extension, intensity and localization of all types of defect present. • Instrumental analysis: mechanical characterization of materials based on low-invasive investigations (NDT). For each significant parameter is assigned a numeric value that will form the basis for the calculation of the function of judgment of the single element (Fe). Adding the evaluation carried out for every individual element that make up the bridge and comparing this value to the sum of the defects that may potentially occur in the observed structure, you obtain the function evaluation of the whole structure (Fs). The parameters for the assessment of the condition of the structure are therefore: • data observable during visual inspections; technical arguments made by experts about the static scheme of the structure from which flows the importance that can have the location of the defect within the element on which it appears, • the results of instrumental tests carried out on the material constituting the bridge. The innovative aspect of the proposal, compared to the existing methods, is the introduction of two factors by which you can evaluate the location of the damage (Li), and use the mechanical characterization of the material as a parameter of judgment (Ti). In support of the calculation method I proposed the Evaluation Tables to be completed during the visual inspections to note down observations. In this way you can make it clear how, starting from what was found during the inspection, for each structural element, it was possible to issue the final judgment. The applicability of the method was verified by means of application on three real structures. The first two are located in Pixina Manna (Pula) and the third structure is located a few kilometres far from the city of Cagliari. Application examples show that the method is an important aid to the evaluation of the structure, providing a guide for the technician who must carry out the survey and directing a uniformity of opinion.

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White, Jonathan Russell. "An inquiry into minimalist phrase structure". Thesis, University College London (University of London), 1999. http://discovery.ucl.ac.uk/1348851/.

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This thesis takes as its starting point the proposal in Kayne (1994) that all syntactic structures are underlyingly spec-head-complement, and that they are right-branching. I will investigate this proposal taking data from English degree constructions, namely result clauses and comparatives. A comparison will be made between these constructions and English VPs, on which the majority of the phrase structure debate in the literature has been based. The evidence for left-branching and for right-branching in VPs will be considered, and similar evidence sought for degree constructions. We will see that VPs have a mostly right-branching structure, although left-branching structures are required in restricted circumstances. Also reason and manner adjuncts are argued to be right-adjoined to the VP node, a conclusion that is re-inforced by considering the constituency of VP adjuncts and some PP sequences noted by Jackendoff (1973). In degree constructions too, we argue that both left-branching and right-branching structures are necessary. My conclusion will be that Kayne's proposal is too strong, even though it is ideal from the perspective of a minimalist approach to syntax.

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Heimberg, Lucas. "Complexity of Normal Forms on Structures of Bounded Degree". Doctoral thesis, Humboldt-Universität zu Berlin, 2018. http://dx.doi.org/10.18452/19205.

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Normalformen drücken semantische Eigenschaften einer Logik durch syntaktische Restriktionen aus. Sie ermöglichen es Algorithmen, Grenzen der Ausdrucksstärke einer Logik auszunutzen. Ein Beispiel ist die Lokalität der Logik erster Stufe (FO), die impliziert, dass Graph-Eigenschaften wie Erreichbarkeit oder Zusammenhang nicht FO-definierbar sind. Gaifman-Normalformen drücken die Bedeutung einer FO-Formel als Boolesche Kombination lokaler Eigenschaften aus. Sie haben eine wichtige Rolle in Model-Checking Algorithmen für Klassen dünn besetzter Graphen, deren Laufzeit durch die Größe der auszuwertenden Formel parametrisiert ist. Es ist jedoch bekannt, dass Gaifman-Normalformen im Allgemeinen nur mit nicht-elementarem Aufwand konstruiert werden können. Dies führt zu einer enormen Parameterabhängigkeit der genannten Algorithmen. Ähnliche nicht-elementare untere Schranken sind auch für Feferman-Vaught-Zerlegungen und für die Erhaltungssätze von Lyndon, Łoś und Tarski bekannt. Diese Arbeit untersucht die Komplexität der genannten Normalformen auf Klassen von Strukturen beschränkten Grades, für welche die nicht-elementaren unteren Schranken nicht gelten. Für diese Einschränkung werden Algorithmen mit elementarer Laufzeit für die Konstruktion von Gaifman-Normalformen, Feferman-Vaught-Zerlegungen, und für die Erhaltungssätze von Lyndon, Łoś und Tarski entwickelt, die in den ersten beiden Fällen worst-case optimal sind. Wichtig hierfür sind Hanf-Normalformen. Es wird gezeigt, dass eine Erweiterung von FO durch unäre Zählquantoren genau dann Hanf-Normalformen erlaubt, wenn alle Zählquantoren ultimativ periodisch sind, und wie Hanf-Normalformen in diesen Fällen in elementarer und worst-case optimaler Zeit konstruiert werden können. Dies führt zu Model-Checking Algorithmen für solche Erweiterungen von FO sowie zu Verallgemeinerungen der Algorithmen für Feferman-Vaught-Zerlegungen und die Erhaltungssätze von Lyndon, Łoś und Tarski.
Normal forms express semantic properties of logics by means of syntactical restrictions. They allow algorithms to benefit from restrictions of the expressive power of a logic. An example is the locality of first-order logic (FO), which implies that properties like reachability or connectivity cannot be defined in FO. Gaifman's local normal form expresses the satisfaction conditions of an FO-formula by a Boolean combination of local statements. Gaifman normal form serves as a first step in fixed-parameter model-checking algorithms, parameterised by the size of the formula, on sparse graph classes. However, it is known that in general, there are non-elementary lower bounds for the costs involved in transforming a formula into Gaifman normal form. This leads to an enormous parameter-dependency of the aforementioned algorithms. Similar non-elementary lower bounds also hold for Feferman-Vaught decompositions and for the preservation theorems by Lyndon, Łoś, and Tarski. This thesis investigates the complexity of these normal forms when restricting attention to classes of structures of bounded degree, for which the non-elementary lower bounds are known to fail. Under this restriction, the thesis provides algorithms with elementary and even worst-case optimal running time for the construction of Gaifman normal form and Feferman-Vaught decompositions. For the preservation theorems, algorithmic versions with elementary running time and non-matching lower bounds are provided. Crucial for these results is the notion of Hanf normal form. It is shown that an extension of FO by unary counting quantifiers allows Hanf normal forms if, and only if, all quantifiers are ultimately periodic, and furthermore, how Hanf normal form can be computed in elementary and worst-case optimal time in these cases. This leads to model-checking algorithms for such extensions of FO and also allows generalisations of the constructions for Feferman-Vaught decompositions and preservation theorems.

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Ho, Sunny Leung Ming. "Repair of degraded concrete structures with composites : columns and slabs with reduced steel area /". View Abstract or Full-Text, 2002. http://library.ust.hk/cgi/db/thesis.pl?CIVL%202002%20HO.

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Westin, Johan. "Ballistic Impact Properties of Fibre-Reinforced Composite Structures". Thesis, KTH, Farkost och flyg, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-39676.

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Livros sobre o assunto "Degrade Structures"

Ebeling, Robert M. Accuracy of response of single-degree-of-freedom systems to ground motion. Vicksburg, Miss: U.S. Army Engineer Waterways Experiment Station, 1997.

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C, Chamis C., e United States. National Aeronautics and Space Administration., eds. First-passage problems: A probabilistic dynamic analysis for degraded structures. [Washington, DC]: National Aeronautics and Space Administration, 1990.

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Tomasz, Parteka, ed. Transformacja zdegradowanych struktur przestrzennych metropolii polskich =: Transformation of degraded spatial structures of Polish metropolises. Warszawa: KPZK PAN, 2005.

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D, Pilkey Walter, e United States. National Aeronautics and Space Administration., eds. Final report on PhD degree for Neil J. Fergusson. [Washington, DC: National Aeronautics and Space Administration, 1992.

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Maymon, Giora. Some engineering applications in random vibrations and random structures. Reston, Va: American Institute of Aeronautics and Astronautics, 1998.

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N, Simons Rainee, Katehi Linda P. B e NASA Glenn Research Center, eds. Novel vertical interconnects with 180 degree phase shift for amplifiers, filters, and integrated antennas. [Cleveland, Ohio]: National Aeronautics and Space Administration, Glenn Research Center, 2001.

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Lazarova, Larisa, e Fatima Kairova. Final qualifying work: Master's degree. ru: INFRA-M Academic Publishing LLC., 2023. http://dx.doi.org/10.12737/1913592.

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The textbook contains recommendations and requirements for the structure and content of graduate qualification works of undergraduates, the main issues of the organization of their implementation. Special attention is paid to the solution of computational and analytical final qualifying works. Meets the requirements of the federal state educational standards of higher education of the latest generation. It is intended to provide methodological assistance in the process of performing the computational and analytical part of the final qualifying work to master's degree students studying in the field of preparation 38.04.08 "Finance and Credit", as well as scientific supervisors of final qualifying works, reviewers, members of state examination commissions.

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Department of Education & Science. South Bank Polytechnic: Degree course in civil and structural engineering : report by HMI. Stanmore: Department of Education and Science, 1991.

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Convegno "Siti minerari dismessi e fenomeni di degrado in rocce evaporitiche" (2007 Bergamo, Italy). Dissesti indotti dall'alterazione di rocce evaporitiche: Atti del Convegno "Siti minerari dismessi e fenomeni di degrado in rocce evaporitiche" : Bergamo, 28-29 settembre 2007. Bologna: Pàtron, 2009.

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Capítulos de livros sobre o assunto "Degrade Structures"

Wang, Lei. "Brief Description of Prestressed Concrete Structures". In Strand Corrosion in Prestressed Concrete Structures, 1–16. Singapore: Springer Nature Singapore, 2023. http://dx.doi.org/10.1007/978-981-99-2054-9_1.

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AbstractStrand corrosion can cause concrete cracking, degrade bond performance at the strand–concrete interface, lead to prestress loss, and deteriorate the capacity of prestressed concrete structures. This book clarifies the mechanical behavior of corroded prestressing strands, corrosion-induced cracking, bond degradation, prestress loss, and structural performance deterioration of prestressed concrete structures and proposes the corresponding prediction models, which has an important guidance for the durability and maintenance design of prestressed concrete structures.

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Wang, Lei. "Bearing Capacity Prediction of Corroded PT Beams Incorporating Grouting Defects and Bond Degradation". In Strand Corrosion in Prestressed Concrete Structures, 225–53. Singapore: Springer Nature Singapore, 2023. http://dx.doi.org/10.1007/978-981-99-2054-9_9.

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AbstractCorrosion can reduce the sectional area of strand, induce concrete cracking, and degrade bond strength, which can further decrease the bearing capacity of prestressed concrete beams. First, an analytical model is proposed to predict the flexural bearing capacity of partially ungrouted post-tensioned concrete beams. Then, a prediction model of corroded prestressed concrete beams is established to calculate the incompatible deformation between strand and concrete under different load conditions.

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Petrosian, Levon Gregory. "Multi-Degree-of-Freedom System". In Dynamics of Structures, 155–71. Cham: Springer Nature Switzerland, 2024. http://dx.doi.org/10.1007/978-3-031-63539-7_8.

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Laurent-Gengoux, Camille, Anne Pichereau e Pol Vanhaecke. "Higher Degree Poisson Structures". In Grundlehren der mathematischen Wissenschaften, 205–32. Berlin, Heidelberg: Springer Berlin Heidelberg, 2013. http://dx.doi.org/10.1007/978-3-642-31090-4_8.

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Wang, Hongnan, e Huabo Liu. "Evaluation and Repair of Steel Structure Damaged by Fire". In Lecture Notes in Civil Engineering, 335–41. Singapore: Springer Nature Singapore, 2023. http://dx.doi.org/10.1007/978-981-99-1748-8_30.

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AbstractIn recent years, steel structures have been widely used in buildings because of their advantages in self-weight and seismic performance. However, due to the great influence of temperature on steel structure, once a fire occurs, it may lead to the destruction of steel structure and even the collapse of the building. In this paper, through the assessment of a steel structure factory after fire, the damage degree of the components and structural integrity of the building are determined, which provides a reliable technical support for the subsequent repair and retrofit work. Based on the extent of damage identified, repairs are performed on the affected members. The analysis results of the rehabilitated structure show that this method is safe and effective.

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Kuhlmann, Marco. "Dependency Structures of Bounded Degree". In Dependency Structures and Lexicalized Grammars, 33–49. Berlin, Heidelberg: Springer Berlin Heidelberg, 2010. http://dx.doi.org/10.1007/978-3-642-14568-1_4.

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Paz, Mario. "Undamped Single Degree-of-Freedom System". In Structural Dynamics, 3–22. Boston, MA: Springer US, 1991. http://dx.doi.org/10.1007/978-1-4684-9907-0_1.

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Paz, Mario. "Damped Single Degree-of-Freedom System". In Structural Dynamics, 23–35. Boston, MA: Springer US, 1991. http://dx.doi.org/10.1007/978-1-4684-9907-0_2.

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Paz, Mario, e William Leigh. "Undamped Single Degree-of-Freedom System". In Structural Dynamics, 3–30. Boston, MA: Springer US, 2004. http://dx.doi.org/10.1007/978-1-4615-0481-8_1.

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Paz, Mario, e William Leigh. "Damped Single Degree-of-Freedom System". In Structural Dynamics, 31–48. Boston, MA: Springer US, 2004. http://dx.doi.org/10.1007/978-1-4615-0481-8_2.

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Trabalhos de conferências sobre o assunto "Degrade Structures"

So, F. F., S. R. Forrest, Y. Q. Shi e W. H. Steier. "Molecular semiconductor multilayer structures". In OSA Annual Meeting. Washington, D.C.: Optica Publishing Group, 1989. http://dx.doi.org/10.1364/oam.1989.mw6.

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Semiconductor quantum wells and superlattice structures have provided many unique properties which cannot be realized using bulk semiconductor materials. Many novel device structures have been developed based on semiconductor quantum well structures, such as semiconductor lasers and photodetectors. The fabrication of these structures is limited to a narrow range of materials which are lattice matched with the exception of stained-layer superlattices. Lattice mismatch induces strain at the semiconductor heterointerface and can create crystal defects such as dislocations which ultimately degrade device performance. On the other hand, molecules in organic semiconductors are held together by relatively weak Van der Waals forces. Therefore, it is possible to fabricate high quality molecular semiconductor multilayer structures where the strain at the heterointerface is small. Hence, a wide range of materials can be utilized for the fabrication of molecular semiconductor superlattice structures.

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Mandisloh, Kristin, Sven Achenbach, Timo Mappes, Tilmann Rogge e Roman Truckenmueller. "Submicron Polymer Flow Cells". In ASME 4th International Conference on Nanochannels, Microchannels, and Minichannels. ASMEDC, 2006. http://dx.doi.org/10.1115/icnmm2006-96147.

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This paper investigates the fabrication processes of polymer micro channels integrated into flow cells. The cross sectional dimensions of these flow cell channels are in the range of microns containing structures or structure details in the submicron range. Single-component and double-component cells are presented. Single-component cells are entirely made of one polymer. They are composed of a micro structured substrate and a cover plate to hermetically seal the subjacent microfluidic structures. Flexible fluidic ports are added to facilitate interfacing. Polymethylmethacrylate (PMMA) is used as an industrially prefabricated foil (HESA®Glas VOS; HESA®Glas HESAlite). Double-component cells are made of spincoated PMMA (MicroChem 950k PMMA A11; AllResist GmbH 950k PMMA A9) that is micro structured on glass substrates prior to sealing with a cover plate. PMMA enables high resolution direct lithographic patterning of the fluidic structures. We apply Deep UV Lithography (DUV) to photochemically degrade PMMA and subsequently dissolve the degraded areas in an organic solvent. This process had previously primarily been utilized to pattern polymer waveguides. For minimum feature size devices, initial samples have been fabricated applying Deep X-Ray Lithography (DXRL) instead of DUV. Final sealing with PMMA cover plates is performed using thermal and UV bonding or solvent welding.

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Cherry, Jeffery L. "Analyses of Containment Structures With Corrosion Damage". In ASME 1996 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 1996. http://dx.doi.org/10.1115/imece1996-0554.

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Abstract Corrosion damage to a nuclear power plant containment structure can degrade the pressure capacity of the vessel. For the low-carbon, low-strength steels used in containments, the effect of corrosion on material properties is discussed. Strain-to-failure tests, in uniaxial tension, have been performed on corroded material samples. Results from the tests were used to select strain-based failure criteria for corroded steel. Using the ABAQUS finite element analysis code, the capacity of a typical PWR Ice Condenser containment with corrosion damage has been studied. Multiple analyses were performed with the locations of the corrosion on the containment, and the amount of corrosion varied in each analysis.

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Stearns, D. G. "Theory of Nonspecular X-ray Scattering from Multilayer Structures". In Physics of X-Ray Multilayer Structures. Washington, D.C.: Optica Publishing Group, 1992. http://dx.doi.org/10.1364/pxrayms.1992.tua3.

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One important type of structural imperfection that can affect the properties of multilayer (ML) structures is interfacial roughness. In x-ray optical ML, roughness both decreases the reflectivity and introduces a background halo that can degrade the resolution of imaging optics. A promising technique for characterizing the roughness of surfaces and interfaces in ML structures is x-ray scattering. The use of x-ray scattering as a structural probe has several important advantages. It is inherently a non-invasive technique, well-suited for dynamic measurements including in situ growth studies. The penetration of x-rays allows both surfaces and buried interfaces to be directly probed. Furthermore, due to the short wavelength of x-rays, x-ray scattering can provide structural information on spatial scales ranging down to atomic dimensions. There is increasing interest to use nonspecular x-ray scattering to study the roughness of interfaces in x-ray ML structures. The first experimental results indicate that the x-ray scattering can exhibit a rich variety of behavior associated with the structural correlations between interfaces1-4. We present a simple theory that, within the limitations imposed by certain simplifying approximations, can provide a straightforward means of relating realistic interface structures to measurements of nonspecular scattering.

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Ng, C. H., N. Ajavakom e F. Ma. "On Response Prediction of Degrading Structures". In ASME 2005 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. ASMEDC, 2005. http://dx.doi.org/10.1115/detc2005-84916.

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All structures degrade when acted upon by cyclic forces associated with earthquakes, high winds, and sea waves. Identification and prediction of degradation is thus a problem of considerable practical significance in the field of engineering mechanics. Under cyclic excitations, system degradation manifests itself in the evolution of the associated hysteresis loops. In this paper, a robust identification algorithm is devised to generate hysteretic models of a deteriorating structure from its experimental load-displacement traces. This algorithm is based upon the generalized Bouc-Wen model and the latest theory of differential evolution, streamlined through global sensitivity analysis. It can account for strength degradation, stiffness degradation, and pinching characteristics in the evolution of hysteretic traces, whereby earlier studies in parametric identification of hysteresis are extended. In addition, it is shown experimentally that a hysteretic model obtained by identification can be used to predict the future performance of a degrading structure. Prediction of degradation through identification is a brute-force approach that offers a close representation of reality. There is not any method based upon the fundamental postulates of mechanics that can predict the response of a degrading structure well beyond its linear range.

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Bhunia, Avijit, Ya-Chi Chen e Chung-Lung Chen. "Impact of Surface Micro-Structures on Liquid Micro-Jet Array Impingement Cooling: Comparison Between Single-Phase and Phase Change Heat Transfer". In ASME/JSME 2011 8th Thermal Engineering Joint Conference. ASMEDC, 2011. http://dx.doi.org/10.1115/ajtec2011-44490.

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This article investigates liquid micro-jet array impingement cooling of a micro-structured surface. An array of 16 free-surface DI water jets, each 125 μm in diameter, and jet Reynolds number ranging between 816 and 2124, is used. A parametric study is carried out with micro-studs of varying size and spacing, implemented on a 1 cm2 base area surface. Based on the decades of research on heat transfer enhancement by surface modification, one would intuitively think that impingement cooling of a micro-structured surface will always be better than that of a plain surface. The current results are in contrary. The micro-structures actually degrade single-phase impingement heat transfer, compared to a plain surface. On the other hand, in the phase change regime they significantly enhance heat transfer, leading to a clear choice of optimal structure. The results are explained in the light of thin film dynamics, heat transfer surface area enhancement and nucleation site density.

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Kim, Hong-Il, Lae-Hyong Kang e Jae-Hung Han. "Measurement of the Thermal Expansion for Space Structures Using Fiber Bragg Grating Sensors and Displacement Measuring Interferometers". In ASME 2008 Conference on Smart Materials, Adaptive Structures and Intelligent Systems. ASMEDC, 2008. http://dx.doi.org/10.1115/smasis2008-479.

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Dimensional stability of the space structures, such as large telescope mirrors or metering substructures, is very important because even extremely small deformations of these structures might degrade the optical performances. Therefore, precise deformation data of the space structures according to environment change are required to design these structures correctly. Also, real-time deformation monitoring of these structures in space environment is demanded to verify whether these structures are properly designed or manufactured. FBG (fiber Bragg grating) sensors are applicable to real time monitoring of the space structure because they can be embedded onto the structures with minimal weight penalty. In this research, therefore, thermal deformation measurement system for the space structures, composed of FBG sensors for real time strain measurement and DMI (displacement measuring interferometers) for accurate specimen expansion data acquisition, is developed. Thermal strains measured by distributed FBG sensors are evaluated by the comparison with the strains obtained by highly accurate DMI.

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McMahan, Jerry A., e Ralph C. Smith. "Uncertainty Quantification for Robust Control Design of Smart Material Systems". In ASME 2013 Conference on Smart Materials, Adaptive Structures and Intelligent Systems. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/smasis2013-3166.

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The objective in robust control design is to provide mechanisms to achieve tracking or stabilization objectives in the presence of unmodeled dynamics. This is usually achieved by assuming worst case model discrepancies which can significantly degrade control authority if the uncertainty bounds are overly conservative. In this paper, we use uncertainty quantification techniques to construct densities for control outputs that can be used to derive optimal robust control designs. We illustrate the performance of these techniques in the context of systems with smart material actuators and sensors.

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Wang, Xintong, Zhaolong Yu e Jørgen Amdahl. "Investigations of Axially Compressed Tubular Structures Subjected to Lateral Indentations". In ASME 2024 43rd International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2024. http://dx.doi.org/10.1115/omae2024-121004.

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Abstract Tubular structures serve as fundamental designs in the offshore industry, indented to support dead weights and endure additional environmental loads. When such structures face potential lateral loads from events like ship collisions or falling objects, alongside working and environmental loadings, their unstable response in the post-buckling stage can lead to catastrophic consequences. It has been observed that existing compressive loads significantly degrade the energy absorption capacity of these structures. Investigations into axially compressed members subjected to lateral indentations are still necessary. In this study, nonlinear finite element methods were employed to explore the responses of typical offshore tubular structures, including a leg of jacket platforms and a monopile of offshore wind turbines. Scaled models were built to maintain consistent diameter/thickness and length/diameter ratios as practical structure. Initial imperfections were introduced in line with offshore standards. Uniaxial compression tests, and lateral indentation tests with varying levels of pre-compression were conducted. Numerical results were compared to predictions based on design rules and previous research. The findings were summarized and discussed.

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Stearns, M. B., e D. G. Stearns. "Optimization of Growth Conditions of Vapor Deposited Mo/Si Multilayers". In Physics of X-Ray Multilayer Structures. Washington, D.C.: Optica Publishing Group, 1992. http://dx.doi.org/10.1364/pxrayms.1992.md2.

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The dependence of the layer structure and interfaces of e-beam deposited Mo/Si multilayers (ML) on the growth conditions has been studied. The substrate temperature was varied over a range of 300-600°K at deposition rates of 1 and 3 Å/sec. The structure of the ML was determined using small-angle x-ray scattering, large-angle x-ray scattering, and cross-sectional high-resolution electron microscopy. The variation of the normal incidence reflectivity was measured as a function of soft x-ray wavelength using synchrotron radiation. We found that the ML structure has a strong dependence on the substrate temperature and a lesser dependence on the deposition rate. ML grown at a substrate temperature of 300°K have Mo layers composed of small crystallites and exhibit significant short wavelength roughness. The lateral extent of the Mo crystallites increases and the interfacial roughness decreases with increasing substrate temperature up to 525-550°K. We attribute the larger Mo crystallites, improved texture and suppression of columnar growth observed at higher substrate temperatures to the increased surface mobility of the adatoms. The optimum conditions to obtain smooth layers by e-beam deposition were found to be a substrate temperature of ~525°K and a deposition rate of ~1 Å/sec. Thus to a great extent the smaller adatom energies of e-beam deposition can be compensated for by increasing the substrate temperature. Above TS~575°K interdiffusion is observed to significantly degrade the ML structure.

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Relatórios de organizações sobre o assunto "Degrade Structures"

Moghimi, Gholamreza, e Nicos Makris. Response Modification of Structures with Supplemental Rotational Inertia. Pacific Earthquake Engineering Research Center, University of California, Berkeley, CA, janeiro de 2024. http://dx.doi.org/10.55461/tihv1701.

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Tall, multistory, buildings are becoming increasingly popular in large cities as a result of growing urbanization trends (United Nations Department of Economic and Social Affairs 2018). As cities continue to grow, many of them along the coasts of continents which are prone to natural hazards, the performance of tall, flexible buildings when subjected to natural hazards is a pressing issue with engineering relevance. The performance of structures when subjected to dynamic loads can be enhanced with various response modification strategies which have been traditionally achieved with added stiffness, flexibility, damping and strength (Kelly et al. 1972; Skinner et al. 1973, 1974; Clough and Penzien 1975; Zhang et al. 1989; Aiken 1990; Whittaker et al. 1991; Makris et al. 1993a,b; Skinner et al. 1993; Inaudi and Makris 1996; Kelly 1997; Soong and Dargush 1997; Constantinou et al. 1998; Makris and Chang 2000a; Chang and Makris 2000; Black et al. 2002, 2003; Symans et al. 2008; Sarlis et al. 2013; Tena-Colunga 1997). Together with the elastic spring that produces a force proportional to the relative displacement of its end-nodes and the viscous dashpot that produces a force proportional to the relative velocity of its end-nodes; the inerter produces a force proportional to the relative acceleration of its end-nodes and emerges as the third elementary mechanical element (in addition to the spring and dashpot) capable for modifying structural response. Accordingly, in this report we examine the seismic performance of multistory and seismically isolated structures when equipped with inerters. In view that the inerter emerges as the third elementary mechanical element for the synthesis of mechanical networks, in Chapter 2 we derive the basic frequency- and time-response functions of the inerter together with these of the two-parameter inertoelastic and inertoviscous mechanical networks. Chapter 3 examines the response of a two-degree-of-freedom (2DOF) structure where the first story is equipped with inerters. Both cases of a stiff and a compliant support of the inerters are examined. The case of two parallel clutching inerters is investigated and the study concludes that as the compliance of the frame that supports the inerters increases, the use of a single inerter offers more favorable response other than increasing the force transferred to the support frame. Chapter 4 examines the seismic response analysis of the classical two-degree-of-freedom isolated structure with supplemental rotational inertia (inerter) in its isolation system. The analysis shows that for the “critical” amount of rotational inertia which eliminates the participation of the second mode, the effect of this elimination is marginal on the structural response since the participation of the second mode is invariably small even when isolation systems without inerters are used. Our study, upon showing that the reaction force at the support of the inerter is appreciable, proceeds with a non-linear response analysis that implements a state-space formulation which accounts for the bilinear behavior of practical isolation system (single concave sliding bearings or lead-rubber bearings) in association with the compliance of the support of the inerter. Our study concludes that supplemental rotational inertia aggravates the displacement and acceleration response of the elastic superstructure and as a result, for larger isolation periods (Tb > 2.5s) the use of inerters in isolation systems is not recommended. Chapter 5 first examines the response analysis of a SDOF elastoplastic and bilinear structure and reveals that when the yielding structure is equipped with supplemental rotational inertia, the equal- displacement rule is valid starting from lower values of the pre-yielding period given that the presence of inerters lengthens the apparent pre-yielding period. The analysis concludes that sup- plemental rotational inertia emerges as an attractive response modification strategy for elastoplastic and bilinear SDOF structures with pre-yielding periods up to T1 = 1.5sec. For larger pre-yielding periods (say T1 > 2.0sec), the effectiveness of inerters to suppress the inelastic response of 2DOF yielding structures reduces; and for very flexible first stories; as in the case of isolated structures examined in chapter 4, the use of inerter at the first level (isolation system) is not recommended. Finally, chapter 6 shows that, in spite of the reduced role of inerters when placed at floor levels other than the first level (they no-longer suppress the induced ground acceleration nor they can eliminate the participation of higher modes), they still manifest a unique role since it is not possible to replace a structure with solitary inerters at higher levels with an equivalent traditional structure without inerters.

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Nagahi, Morteza, Niamat Ullah Ibne Hossain, Safae El Amrani, Raed Jaradat, Laya Khademibami, Simon Goerger e Randy Buchanan. Investigating the influence of demographics and personality types on practitioners' level of systems thinking skills. Engineer Research and Development Center (U.S.), março de 2022. http://dx.doi.org/10.21079/11681/43622.

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Although the application of systems thinking (ST) has become essential for practitioners when dealing with turbulent and complex environments, there are limited studies available in the current literature that investigate how the ST skills of practitioners vary with regard to demographic factors and personality types (PTs). To address this gap, this article uses a structural equation modeling approach to explore the relationship be-tween practitioners’ ST skills, PT, and a set of demographic factors. The demographic factors included in the study are education level, the field of the highest degree, organizational ownership structure, job experience, and current occupation type. A total of 99 engineering managers, 104 systems engineers (SEs), and 55 practitioners with other occupations participated in this article. Results showed that the education level, the field of the highest degree, PT, organizational ownership structure, and current job experience of practitioners influenced their level of ST skills. Additionally, the current occupation type of practitioners partially affects their level of ST skills. An in-depth analysis was also conducted using multiple group analysis to show how seven ST skills of the practitioners vary across their level of education. Taken together, the findings of the study suggest that PT and a set of demographic factors influence the overall ST skill of the practitioners.

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Gottzein, Ruediger. Future NATO Force Structures - Increased Degree of Multinationality? German Experiences and Perspectives. Fort Belvoir, VA: Defense Technical Information Center, janeiro de 2001. http://dx.doi.org/10.21236/ada403798.

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Mahmoud, Hussam, Emad Hassan e Guillermo Riveros. Experimental evaluation of steel beams with mechanical section reduction retrofitted with fiber polymers. Engineer Research and Development Center (U.S.), agosto de 2024. http://dx.doi.org/10.21079/11681/49188.

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Steel elements working in a harsh environment can be exposed to corrosion that degrades their performance and threatens the integrity of the whole structure. Recent studies propose using carbon (CFRP) and basalt (BFRP) fiber–reinforced polymers to repair corroded steel cross sections; however, most of these studies have not explored many of the structural characteristics, including ductility. In this study, we conduct a series of full-scale experimental tests to investigate the impact of corrosion, represented as mechanical section reduction, on steel beams as well as the impact of repairing the beams using CFRP and BFRP in enhancing the beams’ structural performance. Mechanical section reduction, introduced to the flange and web elements, is used to establish a baseline dataset that captures the impact of repairs in the absence of corrosion. Four-point bending loading conditions are utilized for all tested beams. The results show that the reduction of the flange and web section lowers the beams’ yielding load by 10% and 8%, respectively, compared with a beam with a full cross section. Utilizing CFRP and BFRP patches can partially restore the corroded beams’ ductility; however, the BFRP is outperforming the CFRP in improving their ultimate strength by 10% and enhancing their ductility by 10%.

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Gao, Elizabeth, David Pogue, Debbie Lawrence, Ashok Kumar, Christopher Boyd, Samantha Mabry, Paul Braun et al. Temperature-insensitive, high-density lithium-ion batteries. Engineer Research and Development Center (U.S.), dezembro de 2024. https://doi.org/10.21079/11681/49498.

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Lithium-ion (Li-ion) batteries are a preferred energy storage solution for their generation capacity and power density; however, their chemical in-stability at high temperature raises major concerns relating to their safety, reliability, and lifespan. Over time, natural temperature cycling of Li-ion batteries degrades the depth of discharge and degree of charge that can be achieved, limiting the cell performance and storage capacity as the micro-structure of the anode and cathode interfaces are altered. To ensure safe, continuous, and high-performance Li-ion batteries, improvements are needed to counteract the degradation of their electrochemically active and inactive chemical components. Using solid-state alternatives to Li-ion components, high performance may be maintained while improving the stability of the ion during charging. The synthesis, characterization, theory, simulation, and fabrication of dense high-voltage cathodes, solid electrolytes, and metal anodes are detailed in this report to establish the underpinning science and technology required to improve the stability of Li-ion batteries.

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Farrar, Charles, e Michael Todd. A Structural engineering Graduate Degree Program with specialization in structural health monitoring & non-destructive evaluation. Office of Scientific and Technical Information (OSTI), junho de 2022. http://dx.doi.org/10.2172/1874143.

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Brown, Alexander, Blake Lance, Michael Clemenson, Samuel jones, Michael Benson e Chris Elkins. Dispersion Validation for Flow Involving a Large Structure Revisited: 45 Degree Rotation. Office of Scientific and Technical Information (OSTI), setembro de 2020. http://dx.doi.org/10.2172/1670514.

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Petti, Jason P. Structural integrity analysis of the degraded drywell containment at the Oyster Creek Nuclear generating station. Office of Scientific and Technical Information (OSTI), janeiro de 2007. http://dx.doi.org/10.2172/903434.

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Nie, J., J. Braverman, C. Hofmayer, Y. Choun, M. Kim e I. Choi. Fragility Analysis Methodology for Degraded Structures and Passive Components in Nuclear Power Plants - Illustrated using a Condensate Storage Tank. Office of Scientific and Technical Information (OSTI), junho de 2010. http://dx.doi.org/10.2172/1015132.

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Villamil, Julie, Caique Lara, Anthony Abrahao, Aparna Arvelli, Guilherme Daldegan, Sharif Sarker e Dwayne McDaniel. Development of a Pipe Crawler Inspection Tool for Fossil Energy Power Plants. Florida International University, outubro de 2021. http://dx.doi.org/10.25148/mmeurs.009772.

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Fossil fuel power plants are complex systems containing multiple components that create extreme environments for the purpose of extracting usable energy. Failures in the system can lead to increased down time for the plant, reduction of power and significant cost for repairs. In the past, inspections and maintenance of the plant's superheater tubes has been predominantly manual, laborious, and extremely time consuming. This is due to the pipe's small diameter size (between 1.3 and 7.6 cm) and the coiled structure of the tubing. In addition, the tubes are often stacked close to each other, limiting access for external inspection. Detection of pipe degradation, such as increased levels of corrosion, creep, and the formation of micro-cracks is possible using standard non-destructive evaluation (NDE) methods, including ultrasonic, radiography and electromagnetic methods. However, when the access to the sub-systems is limited or the configuration of the structure is prohibitive, alternative methods are needed for deploying the NDE tools. This research effort considers a novel robotic inspection system for the evaluation of small pipes found in typical boiler superheaters that have limited access. The pipe crawler system is an internal inspection device that can potentially navigate through the entire pipe length using linear actuators to grip the walls and inch along the pipe. The modular nature of the system allows it to traverse through straight sections and multiple 90-degree and 180-degree bends. The crawler is also capable of providing visual inspections, ultrasonic thickness measurements, and generating inner diameter surface maps using LiDAR (light detection and ranging). Ultimately, the development of this robotic inspection tool can provide information regarding the structural integrity of key pipeline components in fossil fuel power plants that are not easily accessible

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