Littérature scientifique sur le sujet « Crest distribution »
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Articles de revues sur le sujet "Crest distribution"
1
Kriebel, D. L., et T. H. Dawson. « Distribution of Crest Amplitudes in Severe Seas With Breaking ». Journal of Offshore Mechanics and Arctic Engineering 115, no 1 (1 février 1993) : 9–15. http://dx.doi.org/10.1115/1.2920097.
Texte intégralRésumé :
A theoretical model is presented for the probability distribution of wave crest amplitudes in severe seas states with wave breaking. As the severity of a sea state increases, nonlinearities cause an increase in the amplitudes of the largest wave crests with a subsequent modification of the distribution of wave crest amplitudes from the linear Rayleigh theory. In this paper, a theory for the probabilities of these nonlinear crest amplitudes is first reviewed based on earlier work. The further limitations on these nonlinear crest amplitudes by wave breaking are then considered. As a result, a theoretical model is presented to account for both: 1) the nonlinear increase in the highest wave crests, and 2) the selective reduction of some fraction of these high crests due to wave breaking. This model is then verified using several sets of laboratory data for severe breaking seas having approximate JONSWAP wave spectra.
2
Forristall, George Z., Stephen F. Barstow, Harald E. Krogstad, Marc Prevosto, Paul H. Taylor et Peter S. Tromans. « Wave Crest Sensor Intercomparison Study : An Overview of WACSIS ». Journal of Offshore Mechanics and Arctic Engineering 126, no 1 (1 février 2004) : 26–34. http://dx.doi.org/10.1115/1.1641388.
Texte intégralRésumé :
The Wave Crest Sensor Intercomparison Study (WACSIS) was designed as a thorough investigation of the statistical distribution of crest heights. Measurements were made in the southern North Sea during the winter of 1997–1998 from the Meetpost Noordwijk in 18 m water depth. The platform was outfitted with several popular wave sensors, including Saab and Marex radars, an EMI laser, a Baylor wave staff and a Vlissingen step gauge. Buoys were moored nearby to obtain directional spectra. Two video cameras viewed the ocean under the wave sensors and their signals were recorded digitally. The data analysis focused on comparisons of the crest height measurements from the various sensors and comparisons of the crest height distributions derived from the sensors and from theories. Some of the sensors had greater than expected energy at high frequencies. Once the measurements were filtered at 0.64 Hz, the Baylor, EMI and Vlissingen crest height distributions matched quite closely, while those from the other sensors were a few percent higher. The Baylor and EMI crest distributions agreed very well with the statistics from second order simulations, while previous parameterizations of the crest height distribution were generally too high. We conclude that crest height distributions derived from second order simulations can be used with confidence in engineering calculations. The data were also used in investigations of crest and trough shapes and the joint height/period distribution.
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Wang, Yongfei, Junru Li, Zhenyu Wu, Jiankang Chen, Chuan Yin et Kang Bian. « Dynamic Risk Evaluation and Early Warning of Crest Cracking for High Earth-Rockfill Dams through Bayesian Parameter Updating ». Applied Sciences 10, no 21 (29 octobre 2020) : 7627. http://dx.doi.org/10.3390/app10217627.
Texte intégralRésumé :
Crest cracking is one of the most common damage types for high earth-rockfill dams. Cracking risk of dam crest is closely related to the duration of abnormal deformation state. In this paper, a methodology for dynamic risk evaluation and early warning of crest cracking for high earth-rockfill dams is proposed and mainly consists of: (a) The discrimination of abnormal deformation state related to crest cracking, which is implemented by comparing the crest settlement inclination with the threshold value. (b) Computation of crest cracking probability and estimation of cracking time. The exponential distribution is adopted to represent the probability distribution of the duration TAS of abnormal state before crest cracking. Then the crest cracking probability in a given time can be computed by integration with respect to TAS. Inversely, the cracking time corresponding to a given probability can be estimated. (c) Determination of the values of probability adopted to early warn crest cracking, which are suggested to be selected by statistical analysis of the calculated probabilities at the observed cracking times. (d) Bayesian estimation and updating of probability distribution of the parameter λ in the PDF of TAS, according to observed durations of abnormal state before crest cracking. The methodology is illustrated and verified by the case study for an actual earth-rockfill dam, of which crest cracking and recracking events were observed during the periods of high reservoir level. According to the observed values of TAS, the probability distribution for λ is progressively updated and the dispersion of the distributions of λ gradually decreases. The crest cracking probability increases with the duration of abnormal state and the width of confidence interval of the estimated cracking probability progressively contracts with the updating of the distribution for λ. Finally, the early warning of crest cracking for the dam is investigated by estimating the lower limit of cracking time. It is shown that early warning of crest cracking can be issued from at least 20 days ahead of the occurrence of crest cracking event. The idea of using duration of abnormal state of crest settlement to evaluate crest cracking risk of the earth-rockfill dam in this paper may be applicable to other dams.
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Duband, J. L., et J. P. Thiery. « Distribution of laminin and collagens during avian neural crest development ». Development 101, no 3 (1 novembre 1987) : 461–78. http://dx.doi.org/10.1242/dev.101.3.461.
Texte intégralRésumé :
The distribution of type I, III and IV collagens and laminin during neural crest development was studied by immunofluorescence labelling of early avian embryos. These components, except type III collagen, were present prior to both cephalic and trunk neural crest appearance. Type I collagen was widely distributed throughout the embryo in the basement membranes of epithelia as well as in the extracellular spaces associated with mesenchymes. Type IV collagen and laminin shared a common distribution primarily in the basal surfaces of epithelia and in close association with developing nerves and muscle. In striking contrast with the other collagens and laminin, type III collagen appeared secondarily during embryogenesis in a restricted pattern in connective tissues. The distribution and fate of laminin and type I and IV collagens could be correlated spatially and temporally with morphogenetic events during neural crest development. Type IV collagen and lamin disappeared from the basal surface of the neural tube at sites where neural crest cells were emerging. During the course of neural crest cell migration, type I collagen was particularly abundant along migratory pathways whereas type IV collagen and laminin were distributed in the basal surfaces of the epithelia lining these pathways but were rarely seen in large amounts among neural crest cells. In contrast, termination of neural crest cell migration and aggregation into ganglia were correlated in many cases with the loss of type I collagen and with the appearance of type IV collagen and laminin among the neural crest population. Type III collagen was not observed associated with neural crest cells during their development. These observations suggest that laminin and both type I and IV collagens may be involved with different functional specificities during neural crest ontogeny. (i) Type I collagen associated with fibronectins is a major component of the extracellular spaces of the young embryo. Together with other components, it may contribute to the three-dimensional organization and functions of the matrix during neural crest cell migration. (ii) Type III collagen is apparently not required for tissue remodelling and cell migration during early embryogenesis. (iii) Type IV collagen and laminin are important components of the basal surface of epithelia and their distribution is consistent with tissue remodelling that occurs during neural crest cell emigration and aggregation into ganglia.
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FEDELE, FRANCESCO, et M. AZIZ TAYFUN. « On nonlinear wave groups and crest statistics ». Journal of Fluid Mechanics 620 (10 février 2009) : 221–39. http://dx.doi.org/10.1017/s0022112008004424.
Texte intégralRésumé :
We present a second-order stochastic model of weakly nonlinear waves and develop theoretical expressions for the expected shape of large surface displacements. The model also leads to an exact theoretical expression for the statistical distribution of large wave crests in a form that generalizes the Tayfun distribution (Tayfun, J. Geophys. Res., vol. 85, 1980, p. 1548). The generalized distribution depends on a steepness parameter given by μ = λ3/3, where λ3 represents the skewness coefficient of surface displacements. It converges to the Tayfun distribution in narrowband waves, where both distributions describe the crests of all waves well. In broadband waves, the generalized distribution represents the crests of large waves just as well whereas the Tayfun distribution appears as an upper bound and tends to overestimate them. However, the theoretical nature of the generalized distribution presents practical difficulties in oceanic applications. We circumvent these by adopting an appropriate approximation for the steepness parameter. Comparisons with wind-wave measurements from the North Sea suggest that this approximation allows both distributions to assume an identical form with which we can describe the distribution of large wave crests fairly accurately. The same comparisons also show that third-order nonlinear effects do not appear to have any discernable effect on the statistics of large surface displacements or wave crests.
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Cho, Yong Jun. « Joint Distribution of the Wave Crest and Its Associated Period for Nonlinear Random Waves of Finite Bandwidth ». Journal of Marine Science and Engineering 8, no 9 (25 août 2020) : 654. http://dx.doi.org/10.3390/jmse8090654.
Texte intégralRésumé :
The theoretical treatment of statistical properties relevant to nonlinear random waves of finite bandwidth, such as the joint distribution of wave crest and its associated wave period, is an overdue task hampered by the complicated form of the analytical model for sea surface elevation. In this study, we first derive the wave crest distribution based on the simplified version of the Longuet-Higgins’ wave model and proceed to derive the joint distribution of the wave crest and its associated period, and the conditional wave period distribution with a given wave crest, which are of great engineering value. It is shown that the bandwidth of the wave spectrum has a significant influence on the crest distribution, and the significant wave crest is getting larger in an increasing manner as nonlinearity is increased as expected. It also turns out that the positive correlation of wave crest height with its associated period is extended to more massive waves as nonlinearity is enhanced contrary to the general perception in the coastal engineering community that the wave crest is a statistically independent random process with wave period over large waves. The peak period decreases due to the destructive interference of second-order free harmonics.
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Mackie, E. J., R. P. Tucker, W. Halfter, R. Chiquet-Ehrismann et H. H. Epperlein. « The distribution of tenascin coincides with pathways of neural crest cell migration ». Development 102, no 1 (1 janvier 1988) : 237–50. http://dx.doi.org/10.1242/dev.102.1.237.
Texte intégralRésumé :
The distribution of the extracellular matrix (ECM) glycoprotein, tenascin, has been compared with that of fibronectin in neural crest migration pathways of Xenopus laevis, quail and rat embryos. In all species studied, the distribution of tenascin, examined by immunohistochemistry, was more closely correlated with pathways of migration than that of fibronectin, which is known to be important for neural crest migration. In Xenopus laevis embryos, anti-tenascin stained the dorsal fin matrix and ECM along the ventral route of migration, but not the ECM found laterally between the ectoderma and somites where neural crest cells do not migrate. In quail embryos, the appearance of tenascin in neural crest pathways was well correlated with the anterior-to-posterior wave of migration. The distribution of tenascin within somites was compared with that of the neural crest marker, HNK-1, in quail embryos. In the dorsal halves of quail somites which contained migrating neural crest cells, the predominant tenascin staining was in the anterior halves of the somites, codistributed with the migrating cells. In rat embryos, tenascin was detectable in the somites only in the anterior halves. Tenascin was not detectable in the matrix of cultured quail neural crest cells, but was in the matrix surrounding somite and notochord cells in vitro. Neural crest cells cultured on a substratum of tenascin did not spread and were rounded. We propose that tenascin is an important factor controlling neural crest morphogenesis, perhaps by modifying the interaction of neural crest cells with fibronectin.
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Lioutas, Anestis, Gregory M. Smith et Henk Jan Verhagen. « SPATIAL DISTRIBUTION OF OVERTOPPING ». Coastal Engineering Proceedings 1, no 33 (14 décembre 2012) : 63. http://dx.doi.org/10.9753/icce.v33.structures.63.
Texte intégralRésumé :
The scope of this research is to find an empirical formula to describe the distribution of wave overtopping in the region behind the crest. A physical model was set up in which irregular waves were generated. In order to find a formula which adequately describes the test observations, the influence of several parameters has been analysed. The proper determination of the crest freeboard, which is a dominant factor, has been investigated. Finally, the test results have been used to assess and compare the existing relevant computational methods.
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Perris, R., D. Krotoski, T. Lallier, C. Domingo, J. M. Sorrell et M. Bronner-Fraser. « Spatial and temporal changes in the distribution of proteoglycans during avian neural crest development ». Development 111, no 2 (1 février 1991) : 583–99. http://dx.doi.org/10.1242/dev.111.2.583.
Texte intégralRésumé :
In this study, we describe the distribution of various classes of proteoglycans and their potential matrix ligand, hyaluronan, during neural crest development in the trunk region of the chicken embryo. Different types of chondroitin and keratan sulfate proteoglycans were recognized using a panel of monoclonal antibodies produced against specific epitopes on their glycosaminoglycan chains. A heparan sulfate proteoglycan was identified by an antibody against its core protein. The distribution of hyaluronan was mapped using a biotinylated fragment that corresponds to the hyaluronan-binding region of cartilage proteoglycans. Four major patterns of proteoglycan immunoreactivity were observed. (1) Chondroitin-6-sulfate-rich proteoglycans and certain keratin sulfate proteoglycans were absent from regions containing migrating neural crest cells, but were present in interstitial matrices and basement membranes along prospective migratory pathways such as the ventral portion of the sclerotome. Although initially distributed uniformly along the rostrocaudal extent of the sclerotome, these proteoglycans became rearranged to the caudal portion of the sclerotome with progressive migration of neural crest cells through the rostral sclerotome and their aggregation into peripheral ganglia. (2) A subset of chondroitin/keratan sulfate proteoglycans bearing primarily unsulfated chondroitin chains was observed exclusively in regions where neural crest cells were absent or delayed from entering, such as the perinotochordal and subepidermal spaces. (3) A subset of chondroitin/keratan sulfate proteoglycans was restricted to the perinotochordal region and, following gangliogenesis, was arranged in a metameric pattern corresponding to the sites where presumptive vertebral arches form. (4) Certain keratan sulfate proteoglycans and a heparan sulfate proteoglycan were observed in basement membranes and in an interstitial matrix uniformly distributed along the rostrocaudal extent of the sclerotome. After gangliogenesis, the neural crest-derived dorsal root and sympathetic ganglia contained both these proteoglycan types, but were essentially free of other chondroitin/keratan-proteoglycan subsets. Hyaluronan generally colocalized with the first set of proteoglycans, but also was concentrated around migrating neural crest cells and was reduced in neural crest-derived ganglia. These observations demonstrate that proteoglycans have diverse and dynamic distributions during times of neural crest development and chondrogenesis of the presumptive vertebrae. In general, chondroitin/keratan sulfate proteoglycans are abundant in regions where neural crest cells are absent, and their segmental distribution inversely correlates with that of neural crest-derived ganglia.
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Thomson, Jim, et Andrew T. Jessup. « A Fourier-Based Method for the Distribution of Breaking Crests from Video Observations ». Journal of Atmospheric and Oceanic Technology 26, no 8 (1 août 2009) : 1663–71. http://dx.doi.org/10.1175/2009jtecho622.1.
Texte intégralRésumé :
Abstract A Fourier-based method is presented to process video observations of water waves and calculate the speed distribution of breaking crest lengths. The method has increased efficiency and robust statistics compared with conventional algorithms that assemble distributions from tracking individual crests in the time domain. The method is tested using field observations (video images of whitecaps) of fetch-limited breaking waves during case studies with low (6.7 m s−1), moderate (8.5 m s−1), and high (12.6 m s−1) wind speeds. The method gives distributions consistent with conventional algorithms, including breaking rates that are consistent with direct observations. Results are applied to obtain remote estimates of the energy dissipation associated with wave breaking.
Thèses sur le sujet "Crest distribution"
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Canard, Maxime. « Controlled generation of unidirectional irregular sea states in experimental and numerical wave tanks ». Electronic Thesis or Diss., Ecole centrale de Nantes, 2024. http://www.theses.fr/2024ECDN0001.
Texte intégralRésumé :
L’objectif de cette thèse est d’améliorer les procédures de génération et de qualification des vagues pour les études de génie océanique. Le cadre est limité aux états de mer unidirectionnels générés dans des bassins d’essais expérimentaux et numériques. Les campagnes expérimentales ont été réalisées dans les bassins de l’ECN et les études numériques à l’aide du solveur HOS-NWT développé par l’ECN. Dans la première partie de la thèse, la propagation des états de mer dans les bassins d’essais est abordée d’un point de vue théorique, expérimental et numérique. Une attention particulière est accordée à l’évolution spatiale du spectre et des statistiques. En outre, les incertitudes expérimentales sont étudiées endétail. La deuxième partie de la thèse se concentre sur le contrôle des champs de vague à n’importe quelle position cible dans le domaine. Tout d’abord, une procédure axée sur la qualité du spectre de houle est étudiée. Ensuite, face à l’influence de la position cible sur les statistiques, une nouvelle procédure est introduite. Elle permet de mieux contrôler les distributions statistiques, indépendamment de la position cibleThe objective of this thesis is to improve the wave generation and qualification procedures in the context of ocean engineering studies. The framework is limited to unidirectional irregular sea states generated in experimental and numerical wave tanks. Experiments were carried out using the ECN facilities and numerical studies were performed using the nonlinear potential wave solver HOS-NWT developed by ECN. In the first part of the thesis, the problem of irregular wave propagation in wave tank environments is addressed from theoretical, experimental, and numerical points of view. Paticular attention is paid to the evolution in space of the wave spectrum and statistics. In addition, experimental uncertainties arestudied in detail. The second part of the thesis focuses on developing methods to better control the wave fields at any target position in the domain. First, a procedure focusing on the quality of the wave spectrum is studied. Then, facing the dependence of the wave statistics on the target location, a new procedure is developed and tested to better control the statistical distributions independently of the target location
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Moore, Josephine. « Strain-Driven Elemental Re-Distribution during Hydration of the Mid-Lower Crust ». Thesis, Curtin University, 2020. http://hdl.handle.net/20.500.11937/79105.
Texte intégralRésumé :
Fluids are vital for the transport of mass and energy through the Earth’s crust and also for its thermodynamic re-equilibration in response to changes in pressure and temperature. Presented here are observations for the coupling between deformation and reaction, mass transport, and variations in trace-element composition and isotope ratios. Overall, this thesis communicates the importance of mid- to lower crustal deformation for mass transfer and in the attainment of equilibria in the presence of fluid.
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Santelli, Cara M. « Geomicrobiology of the ocean crust : the phylogenetic diversity, abundance, and distribution of microbial communities inhabiting basalt and implications for rock alteration processes ». Thesis, Massachusetts Institute of Technology, 2007. http://hdl.handle.net/1721.1/40967.
Texte intégralRésumé :
Thesis (Ph. D.)--Joint Program in Oceanography (Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences; and the Woods Hole Oceanographic Institution), 2007.Includes bibliographical references.
Basaltic ocean crust has the potential to host one of the largest endolithic communities on Earth. This portion of the biosphere, however, remains largely unexplored. In this study, we utilize molecular biological, microscopic, and geochemical tools to gain a better understanding of the geomicrobiology of the ocean crust. Specifically, we examine the phylogenetic diversity of microorganisms inhabiting basaltic lavas, the activities and abundances of these microorganisms, the spatial extent of the biosphere, and the potential effect that microbial activity has on the geochemistry of the ocean crust and overlying water column. Our study demonstrates that young, fresh volcanic lavas near mid-ocean ridges host an incredibly diverse and dense population of microorganisms dominated by Bacteria, quite distinct from the microbial communities found in surrounding deep seawater and hydrothermal vents. Furthermore, these communities may contribute to the elemental cycling of Fe, S, Mn, N, and C in this environment. The inability to definitively identify microorganisms in drill-cores of old (> 15 Ma) ocean crust, however, implies that these once prolific communities may become scarce as the crust ages and moves further away from the ridge axis. Finally, we provide evidence suggesting that these communities are fueled by oxidative alteration reactions occurring in the basaltic crust.
by Cara M. Santelli.
Ph.D.
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Wang, Qian. « A geological traverse across the Jack Hills Metasedimentary Belt, Western Australia : Isotopic constraints on the distribution of proterozoic rocks and the evolution of Hadean Crust ». Thesis, Curtin University, 2014. http://hdl.handle.net/20.500.11937/2275.
Texte intégralRésumé :
Samples of every rock type present along a traverse through the Jack Hills belt were examined and processed for zircon, monazite and xenotime isotopic study. Zircon U-Pb ages range from 1618±22 Ma to 4381±5 Ma, confirming the presence of both Archean and Proterozoic successions. Lutetium-Hf data for Hadean zircons imply a primitive source that was reworked with little juvenile input from the mantle. Monazite data confirm that the Archean rocks were metamorphosed at 2.65 Ga.
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Mendes, Luziane Montezoli Damon. « Aspectos bioecol?gicos dos caranguejos do g?nero Uca (Crust?cea, Decapoda, Ocypodidae) no manguezal de Itacuru??/Coroa Grande, Ba?a de Sepetiba, RJ ». Universidade Federal Rural do Rio de Janeiro, 2014. https://tede.ufrrj.br/jspui/handle/jspui/1383.
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Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico - CNPQ
Species of the genus Uca Leach 1814, have wide distribution in tropical, subtropical and temperate regions of the world, especially as a species excavators substrate, activity is important the processes of energy transfer and nutrient cycling, and is considered a keystone species in the ecosystem. This study was conducted with the aim of investigate the ecology distribution, population biology and somatic growth and natural mortality of the genus Uca in Itacuru??/Coroa Grande mangrove, Sepetiba Bay- RJ. Sampling was conducted in the right bank of the Draga river and Itingussu river during May/2010 to April/2011. The samplings were made monthly by two collectors during 10 minutes in low tide, digging sediment and removing crabs. Sediment samples were collected in 72 subareas of 5x5m, to determine the granulometry, organic matter, calcium, phosphor and metal zinco e manganese. They were studied seven species of the genus Uca: Uca cumulanta, Uca leptodactylus, Uca rapax, Uca thayeri, Uca uruguayensis, Uca mordax and Uca vocator. Uca cumulanta was the more abundant species and Uca vocator the rarer.The results indicated that distribution of the species was influenced by abiotic factors, being the main limiting factors: salinity, sediment grain size, organic matter, concentrations of phosphor and metals, zinc and manganese. Only air temperature presented correlatin with the abundance of the ovigerous females. During the study period was collected a total of 4234 crabs, with 2570 males and 1664 females (61 ovigerous females). The results of the mean size revealed the occurrence of significant differences between the sexes, with a predominance of larger males, for the most populations. Only the females of U. cumulanta presented larger mean size compared to males, and U. thayeri no difference between the sexes. The results of the growth dynamics revealed that a longevity for the study populations ranged from 3.27 to 4.22 years. U. thayeri was the species with the lowest difference in relation to longevity between the sexes, with 3.43 years for males and 3.53 years for females, and U. leptodactylus showed higher amplitude, with 3.43 years for males and 4 07 years for females. The coefficients of natural mortality showed no marked inter and intraspecific differences according to species and sexes, although the values of natural mortality have been higher on males than females
As esp?cies do g?nero Uca possuem ampla distribui??o nas regi?es tropicais, subtropicais e temperadas do mundo, destacando-se como esp?cies escavadoras do substrato, atividade importante para os processos de transfer?ncia de energia e ciclagem de nutrientes e ? considerada uma esp?cie-chave do ecossistema. Este trabalho foi realizado com objetivo de analisar a biologia populacional, distribui??o ecol?gica, crescimento som?tico e mortalidade natural das esp?cies do g?nero Uca no manguezal de Itacuru?a/Coroa Grande, Ba?a de Sepetiba ? RJ. A amostragem foi realizada ? margem direita do rio da Draga e do Rio Itingussu, em tr?s grades (0, 100 e 200 m), durante o per?odo de maio/2010 a abril/2011, mensalmente, durante a mar? baixa, por 10 minutos, atrav?s de coletas manuais escavando o sedimento e removendo os caranguejos. Amostras do sedimento foram coletadas nas 72 sub?reas de 5x5m, para determinar o tamanho das part?culas, mat?ria org?nica, teor de c?lcio, f?sforo e os metais, ferro, zinco e mangan?s. Foram capturadas sete esp?cies do g?nero Uca: Uca cumulanta, Uca leptodactylus, Uca rapax, Uca thayeri, Uca uruguayensis, Uca mordax e Uca vocator. A esp?cie mais abundante foi U. leptodactylus e U. vocator a mais rara.. As principais vari?veis limitantes da abund?ncia das esp?cies do g?nero Uca no manguezal de Itacuru??/Coroa Grande, foram a salinidade, tamanho dos gr?os do sedimento, teor de mat?ria org?nica, concentra??o de f?sforo e dos metais ferro, zinco e mangan?s. Para as f?meas ov?geras a vari?vel temperatura do ar foi a ?nica, que apresentou correla??o com a abund?ncia desses organismos. Durante o per?odo de estudo foi analisado um total de 4234 caranguejos, sendo 2570 machos e 1664 f?meas (61 f?meas ov?geras). A an?lise dos resultados do tamanho m?dio revelou a ocorr?ncia de diferen?as significativas entre os sexos, com predomin?ncia de machos maiores, para maioria das popula??es. Somente as f?meas de U. cumulanta apresentaram maior tamanho m?dio quando comparadas aos machos, j? U. thayeri n?o apresentou diferen?a significativa entre os sexos. Os resultados da din?mica de crescimento, revelaram que a longevidade para as popula??es em estudo, variou de 3,27 a 4,22 anos. U. thayeri foi a esp?cie que apresentou menor diferen?a em rela??o ? longevidade entre os sexos, com 3,43 anos para machos e 3,53 anos para f?meas, j? U. leptodactylus apresentou maior amplitude, com 3,43 anos para machos e 4,07 anos para f?meas. Os coeficientes de mortalidade natural n?o evidenciaram diferen?as inter e intraespecificas acentuadas de acordo com a esp?cie e o sexo, embora os valores de mortalidade natural tenham sido um pouco mais elevados sobre os machos, do que sobre as f?meas. Palavras-chave: Ba?a de Sepetiba, chama-mar?s, longevidade, padr?o de distribui??o, mortalidade.
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Carcolé, Carrubé Eduard. « Three-dimensional spatial distribution of scatterers in the crust by inversion analysis of s-wave coda envelopes. A case study of Gauribidanur seismic array site (Southern india) and Galeras volcano (South-western Colombia) ». Doctoral thesis, Universitat Ramon Llull, 2006. http://hdl.handle.net/10803/9321.
Texte intégralRésumé :
In this thesis, coda waves recorded by local seismographic networks will be analyzed to estimate the three-dimensional spatial distribution of scatterers (SDS). This will be done by using the single scattering approximation. This approach leads to a huge system of equations that can not be solved by traditional methods. For the first time, we will use the Simultaneous Iterative Reconstructive Technique (SIRT) to solve this kind of system in seismological applications. SIRT is slow but provides a means to carry out the inversion with greater accuracy. There is also a very fast non-iterative method that allows to carry out the inversion 102 times faster, with a higher resolution and reasonable accuracy: the Filtered Back-Projection (FBP). If one wishes to use this technique it is necessary to adapt it to the geometry of our problem. This will be done for the first time in this thesis. The theory necessary to carry out the adaptation will be developed and a simple expression will be derived to carry out the inversion.FBP and SIRT are then used to determine the SDS in southern India. Results are almost independent of the inversion method used and they are frequency dependent. They show a remarkably uniform distribution of the scattering strength in the crust around GBA. However, a shallow (0-24 km) strong scattering structure, which is only visible at low frequencies, seems to coincide with de Closepet granitic batholith which is the boundary between the eastern and western parts of the Dharwar craton.
Also, the SDS is estimated for the Galeras volcano, Colombia. Results reveal a highly non-uniform SDS. Strong scatterers show frequency dependence, which is interpreted in terms if the scale of the heterogeneities producing scattering. Two zones of strong scattering are detected: the shallower one is located at a depth from 4 km to 8 km under the summit whereas the deeper one is imaged at a depth of ~37 km from the Earth's surface. Both zones may be correlated with the magmatic plumbing system beneath Galeras volcano. The second strong scattering zone may be probably related to the deeper magma reservoir that feeds the system.
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Izadparast, Amir Hossein. « Semi-empirical Probability Distributions and Their Application in Wave-Structure Interaction Problems ». Thesis, 2010. http://hdl.handle.net/1969.1/ETD-TAMU-2010-12-8763.
Texte intégralRésumé :
In this study, the semi-empirical approach is introduced to accurately estimate
the probability distribution of complex non-linear random variables in the field of wavestructure
interaction. The structural form of the semi-empirical distribution is developed
based on a mathematical representation of the process and the model parameters are
estimated directly from utilization of the sample data. Here, three probability
distributions are developed based on the quadratic transformation of the linear random
variable. Assuming that the linear process follows a standard Gaussian distribution, the
three-parameter Gaussian-Stokes model is derived for the second-order variables.
Similarly, the three-parameter Rayleigh-Stokes model and the four-parameter Weibull-
Stokes model are derived for the crests, troughs, and heights of non-linear process
assuming that the linear variable has a Rayleigh distribution or a Weibull distribution.
The model parameters are empirically estimated with the application of the conventional
method of moments and the newer method of L-moments. Furthermore, the application
of semi-empirical models in extreme analysis and estimation of extreme statistics is discussed. As a main part of this research study, the sensitivity of the model statistics to
the variability of the model parameters as well as the variability in the samples is
evaluated. In addition, the sample size effects on the performance of parameter
estimation methods are studied.
Utilizing illustrative examples, the application of semi-empirical probability
distributions in the estimation of probability distribution of non-linear random variables
is studied. The examples focused on the probability distribution of: wave elevations and
wave crests of ocean waves and waves in the area close to an offshore structure, wave
run-up over the vertical columns of an offshore structure, and ocean wave power
resources. In each example, the performance of the semi-empirical model is compared
with appropriate theoretical and empirical distribution models. It is observed that the
semi-empirical models are successful in capturing the probability distribution of
complex non-linear variables. The semi-empirical models are more flexible than the
theoretical models in capturing the probability distribution of data and the models are
generally more robust than the commonly used empirical models.
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Nazareth, Julie Jeannine. « The Structure of the Crust and Distribution of Earthquakes in Southern California ». Thesis, 2002. https://thesis.library.caltech.edu/6821/1/Nazareth_jj_2002.pdf.
Texte intégralRésumé :
The lithologically and tectonically complex crust of southern California and the current broad deformation zone accommodating the relative motion between the Pacific
and North American plates, result in significant variations in style, depth distribution, and rate of earthquakes, and thus also in the seismic hazard across southern California.
Although the thickness of the seismogenic crust is an important parameter in seismic hazard analysis, it has never been determined systematically for southern California. Seismogenic thickness can be predicted by the depth distribution of the moment release of regional seismicity. The seismogenic thickness of southern California is highly variable, ranging from less than 10 km in the Salton Trough to greater than 25 km at the southwestern edge of the San Joaquin Valley. On average, the seismogenic thickness of southern California is 15.0 km. Seismogenic thickness along the major strike slip systems of southern California can vary significantly along strike. Fault segmentation based upon surface features does not correspond to the variation in seismogenic thickness and thus the potential down-dip width of the fault. A model of the broad scale features of the crust and upper
mantle structure of the borderland-continent transition zone adjacent to Los Angeles constrains the crustal thickness and the location and width of the transition zone. The data require the Moho to deepen significantly to the north, dramatically increasing the crustal thickness over a relatively short distance of 20-25 km. The Moho is coherent and laterally continuous beneath the Inner California Borderland and transition zone. The Inner Borderland seems to be modified and thickened oceanic crust, with the oceanic upper mantle intact beneath it. The static stress change triggering model has some validity and can be useful in explaining apparently triggered seismicity within one fault length of a large mainshock. However, because its applicability varies between different sequences, its general application to seismic hazard evaluation requires more refinement and the inclusion
of parameters such as tectonic regime, regional stress state, and fault strength.
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Redinger, Scott. « A study of subgrain diameter and circularity distributions for crept single crystal NaC1 ». 1997. http://catalog.hathitrust.org/api/volumes/oclc/37429097.html.
Texte intégralRésumé :
Thesis (M.S.)--University of Wisconsin--Madison, 1997.Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaf 47).
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Tian, Zhu. « Tracing on-axis diffuse fluids by chalcophile elements distribution in upper oceanic crust at Pito Deep, East Pacific Rise ». Thesis, 2016. http://hdl.handle.net/1828/7646.
Texte intégralRésumé :
Mid-ocean ridge hydrothermal systems play an important role in the cycling of energy and mass between the solid earth and oceans. The on-axis low-temperature diffuse fluids (temperature lower than ~100 °C) carry ~90% of the on-axis heat fluxes, but diffuse fluids generation is poorly constrained. This study uses the abundance of the chalcophile elements, which form metal-sulphides in the rock record, to test models for diffuse fluids generation. These include mixing between seawater and high-temperature hydrothermal fluids and conductive cooling of high- temperature hydrothermal fluids.
This thesis determined the concentrations of the elements of interest (As, Mo, Ag, Cd, Sn, and Tl) in geological reference materials using standard addition method in ICP-MS. These values were used to calibrate the analysis of samples from Pito Deep to trace the abundance of these elements within the upper oceanic crust. The results show that the Zn, Cu, As, Ag, Cd, Tl, and Pb are generally depleted in sheeted dikes and enriched in the lava unit and/or the transition zone, which is consistent with previous studies on fast-spreading EPR crust at Hole 504B, Hess Deep and Hole 1256D. The enrichment of these elements in the lava unit and/or the transition zone suggests that cooling high-temperature hydrothermal fluids to form diffuse fluids occurred in this
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iv area of the oceanic crust. Molybdenum and Sb are added into all units of the crust by
recharging seawater. The concentrations of chalcophile elements in diffuse fluids were calculated by a mass balance. The results of this study favored a diffuse fluids generation model that involves mixing of seawater and high-temperature hydrothermal fluids. Results also show that the observed concentrations of Mo and Sb requires extra input source besides recharging seawater and oceanic crust, possibly particulates in seawater.Graduate
juliatian2013@gmail.com
Livres sur le sujet "Crest distribution"
1
Jóźwiak, Waldemar. Stochastic inversion method for modeling the electrical conductivity distribution within the earth's mantle. Warszawa : Institute of Geophysics, PAS, 2001.
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Caputo, Michele. Altimetry data and the elastic stress tensor of subduction zones. [Washington, DC : National Aeronautics and Space Administration, 1985.
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Caputo, Michele. Altimetry data and the elastic stress tensor of subduction zones. Greenbelt, Maryland : National Aeronautics and Space Administration, Goddard Space Flight Center, 1987.
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Caputo, Michele. Altimetry data and the elastic stress tensor of subduction zones. [Washington, DC : National Aeronautics and Space Administration, 1985.
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Baad, Michael F. Geographic distribution of rare plants on public lands within the Red Mountain Study Area and a study of the population dynamics and reproductive biology of McDonald's rock-cress, Arabis mcdonaldiana Eastwood : Final report [for the Bureau of Land Management, Ukiah District Office]. ii, 89 leaves : illustrations, maps, charts, 1987.
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6
Carpenter, Ellen Malinin. An analysis of the migration, location, and distribution of neural crest-derived Schwann cells in chick embryos. 1988.
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Bethke, Craig M. Geochemical Reaction Modeling. Oxford University Press, 1996. http://dx.doi.org/10.1093/oso/9780195094756.001.0001.
Texte intégralRésumé :
Geochemical reaction modeling plays an increasingly vital role in several areas of geoscience, from environmental geochemistry and petroleum geology to the study of geothermal and hydrothermal fluids. This book provides an up-to-date overview of the use of numerical methods to model reaction processes in the Earth's crust and on its surface. Early chapters develop the theoretical foundations of the field, derive a set of governing equations, and show how numerical methods can be used to solve these equations. Other chapters discuss the distribution of species in natural waters; methods for computing activity coefficients in dilute solutions and in brines; the complexation of ions into mineral surfaces; the kinetics of precipitation and dissolution reactions; and the fractionation of stable isotopes. Later chapters provide a large number of fully worked calculation examples and case studies demonstrating the modeling techniques that can be applied to scientific and practical problems. Students in a variety of specialties from low-temperature geochemistry to groundwater hydrology will benefit from the wealth of information and practical applications this book has to offer.
Chapitres de livres sur le sujet "Crest distribution"
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Crocket, J. H. « Distribution of gold in the Earth’s crust ». Dans Gold metallogeny and exploration, 1–36. Boston, MA : Springer US, 1991. http://dx.doi.org/10.1007/978-1-4613-0497-5_1.
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Crocket, J. H. « Distribution of gold in the Earth’s crust ». Dans Gold Metallogeny and Exploration, 1–36. Dordrecht : Springer Netherlands, 1993. http://dx.doi.org/10.1007/978-94-011-2128-6_1.
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VaněK, Jiřř. « Upper Mantle Structure and Velocity Distribution in Eurasia ». Dans The Earth's Crust and Upper Mantle, 246–50. Washington, D. C. : American Geophysical Union, 2013. http://dx.doi.org/10.1029/gm013p0246.
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Čermák, Vladimír, et Louise Bodri. « On the vertical distribution of radiogenic heat production in the continental crust and the estimated Moho heat flow ». Dans Properties and Processes of Earth' Lower Crust, 235–42. Washington, D. C. : American Geophysical Union, 1989. http://dx.doi.org/10.1029/gm051p0235.
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Wei, Shanghai, Jingjing Liu, George Allan, Tania Groutso, John J. J. Chen et Mark P. Taylor. « Aluminium Smelter Crust—Phase Distribution and Structure Analysis of Top Zone Layer ». Dans Light Metals 2020, 644–52. Cham : Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-36408-3_87.
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Dyskin, Arcady V. « Mechanical Properties of the Earth’s Crust with Self-Similar Distribution of Faults ». Dans Lecture Notes in Computer Science, 845–54. Berlin, Heidelberg : Springer Berlin Heidelberg, 2003. http://dx.doi.org/10.1007/3-540-44863-2_83.
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Wang, Chi-Yuen, et Michael Manga. « Earthquakes Influenced by Water ». Dans Lecture Notes in Earth System Sciences, 61–82. Cham : Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-64308-9_4.
Texte intégralRésumé :
AbstractInjecting fluids in the crust, or their extraction, changes pore pressure and poroelastic stresses. Both pressure and stress changes can promote seismicity and, hence, the seismic events are called induced earthquakes. The filling of reservoirs on Earth’s surface can also induce earthquakes from some combination of surface loading and pore pressure changes. Attribution of any given earthquake to human activities, however, is not always straightforward. There remains debate about what controls the magnitude of induced earthquakes, the relative importance of pore pressure changes and poroelastic stresses, and how to best manage injection and extraction to minimize seismicity. As the scale and distribution of subsurface engineering expand globally, we should expect more and larger induced earthquakes in the future.
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Rosentreter, Roger, Himanshu Rai et Dalip Kumar Upreti. « Distribution Ecology of Soil Crust Lichens in India : A Comparative Assessment with Global Patterns ». Dans Terricolous Lichens in India, 21–31. New York, NY : Springer New York, 2013. http://dx.doi.org/10.1007/978-1-4614-8736-4_2.
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Unsworth, Martyn, et Stéphane Rondenay. « Mapping the Distribution of Fluids in the Crust and Lithospheric Mantle Utilizing Geophysical Methods ». Dans Lecture Notes in Earth System Sciences, 535–98. Berlin, Heidelberg : Springer Berlin Heidelberg, 2012. http://dx.doi.org/10.1007/978-3-642-28394-9_13.
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Schiøtte, Lasse. « On the Possible Role of Fluid Transport in the Distribution of U and Pb in an Archaean Gneiss Complex ». Dans Fluid Movements — Element Transport and the Composition of the Deep Crust, 299–317. Dordrecht : Springer Netherlands, 1989. http://dx.doi.org/10.1007/978-94-009-0991-5_25.
Texte intégralActes de conférences sur le sujet "Crest distribution"
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Li, Cuilin, Dingyong Yu, Yangyang Gao et Junxian Yang. « Crest-Height Distribution in Nonlinear Random Wave ». Dans ASME 2009 28th International Conference on Ocean, Offshore and Arctic Engineering. ASMEDC, 2009. http://dx.doi.org/10.1115/omae2009-79249.
Texte intégralRésumé :
Many empirical and theoretical distribution functions for wave crest heights have been proposed, but there is a lack of agreement. With the development of ocean exploitation, waves crest heights represent a key point in the design of coastal structures, both fixed and floating, for shoreline protection and flood prevention. Waves crest height is the dominant parameter in assessing the likelihood of wave-in-deck impact and its resulting severe damage. Unlike wave heights, wave crests generally appear to be affected by nonlinearities; therefore, linear wave theory could not be satisfied to practical application. It is great significant to estimate a new nonlinear wave crest height distribution model correctly. This paper derives an approximation distribution formula based on Stokes wave theory. The resulting theoretical forms for nonlinear wave crest are compared with observed data and discussed in detail. The results are shown to be in good agreement. Furthermore, the results indicate that the new theoretical distribution has more accurate than other methods presented in this paper (e.g. Rayleigh distribution and Weibull distribution) and appears to have a greater range of applicability.
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Scharnke, Jule, et Janou Hennig. « Statistical Analysis of a Set of Basin Waves ». Dans ASME 2011 30th International Conference on Ocean, Offshore and Arctic Engineering. ASMEDC, 2011. http://dx.doi.org/10.1115/omae2011-49974.
Texte intégralRésumé :
In a recent paper the effect of variations in calibrated wave parameters on wave crest and height distributions was analyzed (OMAE2010-20304, [1]). Theoretical distribution functions were compared to wave measurements with a variation in water depth, wave seed (group spectrum) and location of measurement for the same initial power spectrum. The wave crest distribution of the shallow water waves exceeded both second-order and Rayleigh distribution. Whereas, in intermediate water depth the measured crests followed the second order distribution. The distributions of the measured waves showed that different wave seeds result in the same wave height and crest distributions. Measured wave heights were lower closer to the wave maker. In this paper the results of the continued statistical analysis of basin waves are presented with focus on wave steepness and their influence on wave height and wave crest distributions. Furthermore, the sampling variability of the presented cases is assessed.
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Hennig, Janou, Jule Scharnke, Christian E. Schmittner et Joris van den Berg. « ShorTCresT : Directional Wave Measurements at MARIN ». Dans ASME 2015 34th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/omae2015-41169.
Texte intégralRésumé :
The objective of the ShortCresT JIP Joint Industry Project was to take into account short-crestedness in the design of offshore structures against extreme waves based on a good description of their spectral characteristics, statistics, kinematics, breaking and loading and to deliver a concrete (empirical) design methodology. The second order wave crest distribution showed to be a good basis for the estimation of a design wave crest. However, depending on sea state steepness and directional spreading, crests may exceed the second order distribution in some severe seas by around 10 %. On the other hand, the very highest crests may be limited by breaking and even fall below the second order model. This paper addresses experimental results from the MARIN where directional wave measurements were carried out in two dimensions. Conclusions with respect to evolution of wave spectra in the basin, directional analysis and calibration, sampling variability, local variability of measured crest heights and measured crest height distributions due to different types of spreading are evaluated. Furthermore, the influence of the type of instrumentation and the effect of the spectral high frequency tail on the crest distributions are assessed.
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Buchner, Bas, George Forristall, Kevin Ewans, Marios Christou et Janou Hennig. « New Insights in Extreme Crest Height Distributions : A Summary of the ‘CresT’ JIP ». Dans ASME 2011 30th International Conference on Ocean, Offshore and Arctic Engineering. ASMEDC, 2011. http://dx.doi.org/10.1115/omae2011-49846.
Texte intégralRésumé :
The objective of the CresT JIP was ‘to develop models for realistic extreme waves and a design methodology for the loading and response of floating platforms’. Within this objective the central question was: ‘What is the highest (most critical) wave crest that will be encountered by my platform in its lifetime?’ Based on the presented results for long and short-crested numerical, field and basin results in the paper, it can be concluded that the statistics of long-crested waves are different than those of short-crested waves. But also short-crested waves show a trend to reach crest heights above second order. This is in line with visual observations of the physics involved: crests are sharper than predicted by second order, waves are asymmetric (fronts are steeper) and waves are breaking. Although the development of extreme waves within short-crested sea states still needs further investigation (including the counteracting effect of breaking), at the end of the CresT project the following procedure for taking into account extreme waves in platform design is recommended: 1. For the wave height distribution, use the Forristall distribution (Forristall, 1978). 2. For the crest height distribution, use 2nd order distribution as basis. 3. Both the basin and field measurements show crest heights higher than predicted by second order theory for steeper sea states. It is therefore recommended to apply a correction to the second order distribution based on the basin results. 4. Account for the sampling variability at the tail of the distribution (and resulting remaining possibility of higher crests than given by the corrected second order distribution) in the reliability analysis. 5. Consider the fact that the maximum crest height under a complete platform deck can be considerably higher than the maximum crest at a single point.
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Hagen, O̸istein. « Wave Distributions and Sampling Variability ». Dans ASME 2007 26th International Conference on Offshore Mechanics and Arctic Engineering. ASMEDC, 2007. http://dx.doi.org/10.1115/omae2007-29584.
Texte intégralRésumé :
The paper describes the effect of sampling variability on the predicted extreme individual wave height and the predicted extreme individual crests height for long return periods, such as for the 100-year maximum wave height and 100-year maximum crest height. We show that the effect of sampling variability is different for individual crest or wave height as compared to for significant wave height. The short term wave statistics is modeled by the Forristall crest height distribution and the Forristall wave height distribution [3,4]. Samples from the 3-hour Weibull distribution are simulated for 100.000 years period, and the 100-year extreme values for wave heights and crest heights determined for respectively 20 minute and 3 hour sea states. The simulations are compared to results obtained by probabilistic analysis. The paper shows that state of the art analysis approaches using the Forristall distributions give about unbiased estimates for extreme individual crest or wave height if implemented appropriately. Direct application of the Forristall distributions for 3-hour sea state parameters give long term extremes that are biased low, and it is shown how the short term distributions can be modified such that consistent results for 20 minute and 3 hour sea states are obtained. These modified distributions are expected applicable for predictions based on hindcast sea state statistics and for the environmental contour approach.
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Buchner, Bas, Radboud van Dijk et Arjan Voogt. « The Spatial Analysis of an Extreme Wave in a Model Basin ». Dans ASME 2007 26th International Conference on Offshore Mechanics and Arctic Engineering. ASMEDC, 2007. http://dx.doi.org/10.1115/omae2007-29409.
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As a pilot study into the understanding of the occurrence of extreme waves, the spatial development of an extreme wave (Ac/Hs = 1.59) in a model basin was investigated. This wave occurred in a wave spectrum that was not extremely steep and non-linear. It is observed that the extreme wave develops in less than half the wavelength from a relatively normal wave into an extreme crest. The wave crest stays high and constant over a large distance (almost 75m). Linear dispersion is not able to predict the wave propagation towards the observed extreme wave crest. Second order theory improves the prediction of the crest amplitude, but not enough. The crest amplitude is still underestimated. This is confirmed by the plots of the probability of extremes. The linear Rayleigh distribution underestimates the crest amplitudes. The second order distribution follows the measurements much better, but also in this case typically the highest 10 crests in a 3 hours storm are underestimated.
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Huang, Zhenjia (Jerry), et Yu Zhang. « Semi-Empirical Single Realization and Ensemble Crest Distributions of Long-Crest Nonlinear Waves ». Dans ASME 2018 37th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/omae2018-78192.
Texte intégralRésumé :
In wave basin model test of an offshore structure, waves that represent the given sea states have to be generated, qualified and accepted for the model test. We normally accept waves in wave calibration tests if the significant wave height, spectral peak period and spectrum match the specified target values. However, for model tests where the responses depend highly on the local wave motions (wave elevation and kinematics) such as wave impact on hull, green water impact on deck and air gap tests, additional qualification checks may be required. For instance, we may need to check wave crest probability distributions to avoid unrealistic wave crest in the test. To date, acceptance criteria of wave crest distribution calibration tests of large and steep waves of three-hour duration (full scale) have not been established. Two purposes of the work presented in the paper are: 1. to define and clarify the wave crest probability distribution of single realization (PDSR) and the probability distribution of wave crest for an ensemble of realizations (PDER) of a given sea state in order to use them appropriately; and 2. to develop semi-empirical probability distributions of nonlinear waves for both PDSR and PDER for easy, practical use. We found that in current practice ensemble and single realization distributions have the potential to be misinterpreted and misused. Clear understanding of the two kinds of distributions will help appropriate offshore design and production unit performance assessments. The semi-empirical formulas proposed in this paper were developed through regression analysis of crest distributions from a large number of sea states and realizations. Wave time series from potential flow simulations, computational fluid dynamics (CFD) simulations and model test results were used to establish the probability distributions. The nonlinear wave simulations were performed for three-hour duration assuming that they were long-crested. The sea states are assumed to be represented by JONSWAP spectrum, where a wide range of significant wave height, peak period, spectral peak parameter, and water depth were considered. Coefficients of the proposed semi-empirical probability distribution formulas, comparisons among crest distributions from numerical simulations and the semi-empirical formulas are presented in this paper.
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Huang, Zhenjia (Jerry), et Qiuchen Guo. « Semi-Empirical Crest Distributions of Long-Crest Nonlinear Waves of Three-Hour Duration ». Dans ASME 2017 36th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/omae2017-61226.
Texte intégralRésumé :
In wave basin model test of an offshore structure, waves that represent the given sea states have to be generated, qualified and accepted for the model test. For seakeeping and stationkeeping model tests, we normally accept waves in wave calibration tests if the significant wave height, spectral peak period and spectrum match the specified target values. However, for model tests where the responses depend highly on the local wave motions (wave elevation and kinematics) such as wave impact, green water impact on deck and air gap tests, additional qualification checks may be required. For instance, we may need to check wave crest probability distributions to avoid unrealistic wave crest in the test. To date, acceptance criteria of wave crest distribution calibration tests of large and steep waves of three-hour duration (full scale) have not been established. The purpose of the work presented in the paper is to provide a semi-empirical nonlinear wave crest distribution of three-hour duration for practical use, i.e. as an acceptance criterion for wave calibration tests. The semi-empirical formulas proposed in this paper were developed through regression analysis of a large number of fully nonlinear wave crest distributions. Wave time series from potential flow simulations, computational fluid dynamics (CFD) simulations and model test results were used to establish the probability distribution. The wave simulations were performed for three-hour duration assuming that they were long-crested. The sea states are assumed to be represented by JONSWAP spectrum, where a wide range of significant wave height, peak period, spectral peak parameter, and water depth were considered. Coefficients of the proposed semi-empirical formulas, comparisons among crest distributions from wave calibration tests, numerical simulations and the semi-empirical formulas are presented in this paper.
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Forristall, George Z., Stephen F. Barstow, Harald E. Krogstad, Marc Prevosto, Paul H. Taylor et Peter Tromans. « Wave Crest Sensor Intercomparison Study : An Overview of WACSIS ». Dans ASME 2002 21st International Conference on Offshore Mechanics and Arctic Engineering. ASMEDC, 2002. http://dx.doi.org/10.1115/omae2002-28438.
Texte intégralRésumé :
The Wave Crest Sensor Intercomparison Study (WACSIS) was designed as a thorough investigation of the statistical distribution of crest heights. Measurements were made in the southern North Sea during the winter of 1997–1998 from the Meetpost Noordwijk in 18 m water depth. The platform was outfitted with several popular wave sensors, including Saab and Marex radars, an EMI laser, a Baylor wave staff and a Vlissingen step gauge. Buoys were moored nearby to obtain directional spectra. Two video cameras viewed the ocean under the wave sensors and their signals were recorded digitally. The data analysis focused on comparisons of the crest height measurements from the various sensors and comparisons of the crest height distributions derived from the sensors and from theories. Some of the sensors had greater than expected energy at high frequencies. Once the measurements were filtered at 0.64 Hz, the Baylor, EMI and Vlissingen crest height distributions matched quite closely, while those from the other sensors were a few percent higher. The Baylor and EMI crest distributions agreed very well with the statistics from second order simulations, while previous parameterizations of the crest height distribution were generally too high. We conclude that crest height distributions derived from second order simulations can be used with confidence in engineering calculations. The data were also used in investigations of crest and trough shapes and the joint height/period distribution.
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Arena, Felice, et Alfredo Ascanelli. « Nonlinear Crest Height Distribution in Three-Dimensional Ocean Waves ». Dans ASME 2008 27th International Conference on Offshore Mechanics and Arctic Engineering. ASMEDC, 2008. http://dx.doi.org/10.1115/omae2008-57944.
Texte intégralRésumé :
The interest and the studies on nonlinear waves are increased recently for their importance in the interaction with floating and fixed bodies. It is also well known that nonlinearities influence wave crest and wave trough distributions, both deviating from Rayleigh law. In this paper a theoretical crest distribution is obtained taking into account the extension of Boccotti’s Quasi Determinism theory, up to the second order for the case of three-dimensional waves, in finite water depth. To this purpose the Fedele & Arena [2005] distribution is generalized to three-dimensional waves on an arbitrary water depth. The comparison with Forristall second order model shows the theoretical confirmation of his conclusion: the crest distribution in deep water for long-crested and short crested waves are very close to each other; in shallow water the crest heights in three dimensional waves are greater than values given by long-crested model.
Rapports d'organisations sur le sujet "Crest distribution"
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Elseroad, Adrien, Joseph St. Peter et Maile Uchida. Biological soil crust distribution on the Boardman Conservation Area. The Nature Conservancy, mars 2010. http://dx.doi.org/10.3411/col.04072147.
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Connell, Sean D. Geologic map of the Albuquerque - Rio Rancho metropolitan area and vicinity, Bernalillo and Sandoval counties, New Mexico. New Mexico Bureau of Geology and Mineral Resources, 2008. http://dx.doi.org/10.58799/gm-78.
Texte intégralRésumé :
This is the most comprehensive compilation of the geology of the Albuquerque Basin to be printed in 30 years. The area covered by this new compilation, though not as large as the earlier map, is presented at a scale nearly four times the detail (1:50,000 scale compared to the earlier map's 1:190,000 scale). This new geologic map is a compilation of sixteen 7.5-min USGS quadrangle maps and encompasses an area from Tijeras Arroyo on the south to Santa Ana Mesa north of Santa Ana and San Felipe Pueblos, and from the crest of the Sandia Mountains westward across the Rio Grande and onto the Llano de Albuquerque (West Mesa) west of the city limits of Albuquerque and Rio Rancho.This geologic map graphically displays information on the distribution, character, orientation, and stratigraphic relationships of rock and surficial units and structural features. The map and accompanying cross sections were compiled from geologic field mapping and additionally from available aerial photography, satellite imagery, and drill-hole data (many published and unpublished reports, examination of lithologic cuttings, and from the interpretation of borehole geophysical log data).The map and accompanying cross sections represent the most informed interpretations of the known faults in the Albuquerque-Rio Rancho area that are presently available. In addition to the positions of many faults, the cross sections show the approximate vertical extent of poorly consolidated earth materials that may pose liquefaction hazards. This map also contains derivative maps selected to portray geologically important features in the metropolitan area, such as elevations of ground water levels, and the mostly buried boundary between generally poorly consolidated and saturated aquifer materials and the more consolidated underlying materials. The gravity anomaly map is a geophysical dataset that shows major geological structures buried beneath the metropolitan area and vicinity.
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King, E. L., A. Normandeau, T. Carson, P. Fraser, C. Staniforth, A. Limoges, B. MacDonald, F. J. Murrillo-Perez et N. Van Nieuwenhove. Pockmarks, a paleo fluid efflux event, glacial meltwater channels, sponge colonies, and trawling impacts in Emerald Basin, Scotian Shelf : autonomous underwater vehicle surveys, William Kennedy 2022011 cruise report. Natural Resources Canada/CMSS/Information Management, 2022. http://dx.doi.org/10.4095/331174.
Texte intégralRésumé :
A short but productive cruise aboard RV William Kennedy tested various new field equipment near Halifax (port of departure and return) but also in areas that could also benefit science understanding. The GSC-A Gavia Autonomous Underwater Vehicle equipped with bathymetric, sidescan and sub-bottom profiler was successfully deployed for the first time on Scotian Shelf science targets. It surveyed three small areas: two across known benthic sponge, Vazella (Russian Hat) within a DFO-directed trawling closure area on the SE flank of Sambro Bank, bordering Emerald Basin, and one across known pockmarks, eroded cone-shaped depression in soft mud due to fluid efflux. The sponge study sites (~ 150 170 m water depth) were known to lie in an area of till (subglacial diamict) exposure at the seabed. The AUV data identified gravel and cobble-rich seabed, registering individual clasts at 35 cm gridded resolution. A subtle variation in seabed texture is recognized in sidescan images, from cobble-rich on ridge crests and flanks, to limited mud-rich sediment in intervening troughs. Correlation between seabed topography and texture with the (previously collected) Vazella distribution along two transects is not straightforward. However there may be a preference for the sponge in the depressions, some of which have a thin but possibly ephemeral sediment cover. Both sponge study sites depict a hereto unknown morphology, carved in glacial deposits, consisting of a series of discontinuous ridges interpreted to be generated by erosion in multiple, continuous, meandering and cross-cutting channels. The morphology is identical to glacial Nye, or mp;lt;"N-mp;lt;"channels, cut by sub-glacial meltwater. However their scale (10 to 100 times mp;lt;"typicalmp;gt;" N-channels) and the unique eroded medium, (till rather than bedrock), presents a rare or unknown size and medium and suggests a continuum in sub-glacial meltwater channels between much larger tunnel valleys, common to the eastward, and the bedrock forms. A comparison is made with coastal Nova Scotia forms in bedrock. The Emerald Basin AUV site, targeting pockmarks was in ~260 to 270 m water depth and imaged eight large and one small pockmark. The main aim was to investigate possible recent or continuous fluid flux activity in light of ocean acidification or greenhouse gas contribution; most accounts to date suggested inactivity. While a lack of common attributes marking activity is confirmed, creep or rotational flank failure is recognized, as is a depletion of buried diffuse methane immediately below the seabed features. Discovery of a second, buried, pockmark horizon, with smaller but more numerous erosive cones and no spatial correlation to the buried diffuse gas or the seabed pockmarks, indicates a paleo-event of fluid or gas efflux; general timing and possible mechanisms are suggested. The basinal survey also registered numerous otter board trawl marks cutting the surficial mud from past fishing activity. The AUV data present a unique dataset for follow-up quantification of the disturbance. Recent realization that this may play a significant role in ocean acidification on a global scale can benefit from such disturbance quantification. The new pole-mounted sub-bottom profiler collected high quality data, enabling correlation of recently recognized till ridges exposed at the seabed as they become buried across the flank and base of the basin. These, along with the Nye channels, will help reconstruct glacial behavior and flow patterns which to date are only vaguely documented. Several cores provide the potential for stratigraphic dating of key horizons and will augment Holocene environmental history investigations by a Dalhousie University student. In summary, several unique features have been identified, providing sufficient field data for further compilation, analysis and follow-up publications.