Articoli di riviste: "Successioni numeriche"

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Winkler, Dániel. "Ecological Succession of Breeding Bird Communities in Deciduous and Coniferous Forests in the Sopron Mountains, Hungary". Acta Silvatica et Lignaria Hungarica 1, n. 1 (1 gennaio 2005): 49–58. http://dx.doi.org/10.37045/aslh-2005-0004.

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The relationship between breeding bird communities and different phases of secondary succession of deciduous (sessile oak – Quercus petraea) and coniferous (spruce – Picea abies) forests in the Sopron Mountains was studied. The bird censi have been carried out in 5 different successional stages using the “double-visit fixed-radius point count technique”. A total of 38 bird species were encountered. There are typical bird communities to order to different stages of forest succession, containing unique bird species or species appearing predominantly in that successional stage. The study has shown structural changes in breeding bird communities during the succession. Bird species richness, density and diversity showed the same trends. Their numerical values were the lowest in the clear-cut areas with young (1-2 year old) plantations, and the highest in the mature stands. After a starting increase (shrub stage) there is a slight decline (10-12 year old stands) because of the canopy closure of the young trees. Further decrease can be observed in the low pole stands, as these habitats are no longer appropriate for species nesting in shrubs and not yet suitable for the hole-nesting ones. Species richness, density and diversity were lower in early pole and older spruce stands than in the corresponding oak stands.

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Monga, Priyanka, Madhav Kumar, Vandana Prasad e Yogesh Joshi. "Palynostratigraphy, palynofacies and depositional environment of a lignite-bearing succession at Surkha Mine, Cambay Basin, north-western India". Acta Palaeobotanica 55, n. 2 (1 dicembre 2015): 183–207. http://dx.doi.org/10.1515/acpa-2015-0010.

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Abstract The paper reports palynology and palynofacies studies of lignite-bearing sediments exposed in an opencast mine succession at Surkha, Bhavnagar District, in the coastal region of Gujarat, India. The study examined the relationships between the palynoflora, sedimentary organic matter and environment at the time of deposition of lignite and associated sediments. Based on dinoflagellate cyst biostratigraphy, the sedimentary succession is dated as early Eocene (Ypresian). Palynofacies studies helped reveal the palaeoenvironmental fluctuations. The dominance of angiosperm pollen grains, freshwater algae, microthyraceous fungi and a large share of land debris in the lower part of the succession suggests a freshwater swamp environment of deposition for the basal lignite facies. Two cenozones - Matanomadiasulcites maximus and Lakiapollis ovatus - were identified in the lower lignite facies, determined from the dominance of these pollen grains in the palynological assemblages. The presence of angiosperm pollen grains and pteridophyte spores in the carbonaceous shale horizon above the lignite facies indicates a change in the depositional regime from freshwater swamp to lagoonal. This was identified as the Arecipites wodehousei cenozone due to its numerical abundance in the assemblage. Dinoflagellate cyst abundance and diversity, and microforaminiferal test linings along with well-sorted terrestrial debris in the mudstone in the upper part of the succession suggest a more open marine estuarine type of depositional environment. The Homotryblium complex along with Cordospheridium fibrospinosum, Kenleyia sp., and Thalassiphora pelagica dinoflagellate cysts are the main representatives of this zone, determined as the Homotryblium tenuispinosum cenozone. The changing depositional settings (freshwater swamp-lagoonal-estuarine) along the vertical succession indicate a marine transgression in this region. Results from palynological studies of early Palaeogene successions of the Cambay and Kutch basins correlate well with the present findings.

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Ma, Wei, Shen Lei, Yujun Sun e Jason Grabosky. "Forest succession in post-agricultural Larix olgensis plantations in northeast China". Journal of Forestry Research 31, n. 6 (11 luglio 2019): 2495–505. http://dx.doi.org/10.1007/s11676-019-00960-7.

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Abstract In order to understand the management of regional vegetation, numerical classification and ordination are widely used to investigate community distribution and vegetation features. In particular, two-way indicator-species analysis programs (TWINSPAN) classifies plots and species into different groups. De-trended correspondence analysis (DCA) and canonical correspondence analysis (CCA) reflects the relationship between community and site conditions. Afforestation with Larix olgensis Herry. Plantations is a suitable restoration strategy on post-agricultural fields in the Lesser Khingan Mountains. The results of this study show how these plantations develop over time to establish a reliable pathway model by measuring and clarifying the succession process. Twenty-eight L. olgensis plantations along a 48-year chronosequence of afforestation were investigated with a quadrat sampling method. Species composition, community structure attributes of diversity, and site conditions were analyzed. Communities were classified by TWINSPAN into five successional stages: immature, juvenile, mid-aged, near-mature and mature. Classifications were validated by DCA and CCA analysis. Site conditions such as soil and litter thickness, soil organic matter, soil density, and pH were measured. Successional stages varied in community composition and species population, accompanied by time from afforestation and a gradient of site conditions. This gradient showed changes in vegetation occurrence and diversity coinciding with changes in soil conditions. The study showed that L. olgensis plantations had marked predominance in growth and were associated with improved soil fertility and the formation of a stable plant community.

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Salugin, A. N. "NUMERICAL MODELING OF SUCCESSIONAL TRANSITIONS IN AGROECOLOGY". Rossiiskaia selskokhoziaistvennaia nauka, n. 1 (2020): 62–65. http://dx.doi.org/10.31857/s2500-2627-2020-1-62-65.

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Salugin, A. N. "Numerical Modeling of Successional Transitions in Agroecology". Russian Agricultural Sciences 46, n. 2 (marzo 2020): 187–91. http://dx.doi.org/10.3103/s1068367420020172.

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Fischer, Martin H., e Richard A. Mills. "A spatial perspective on numerical concepts". Behavioral and Brain Sciences 31, n. 6 (dicembre 2008): 651–52. http://dx.doi.org/10.1017/s0140525x08005670.

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AbstractThe reliable covariation between numerosity and spatial extent is considered as a strong constraint for inferring the successor principle in numerical cognition. We suggest that children can derive a general number concept from the (experientially) infinite succession of spatial positions during object manipulation.

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Chang, Li, Yuanqing He, Taibao Yang, Jiankuo Du, Hewen Niu e Tao Pu. "Analysis of Herbaceous Plant Succession and Dispersal Mechanisms in Deglaciated Terrain on Mt. Yulong, China". Scientific World Journal 2014 (2014): 1–13. http://dx.doi.org/10.1155/2014/154539.

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Ecological succession itself could be a theoretical reference for ecosystem restoration and reconstruction. Glacier forelands are ideal places for investigating plant succession because there are representative ecological succession records at long temporal scales. Based on field observations and experimental data on the foreland of Baishui number 1 Glacier on Mt. Yulong, the succession and dispersal mechanisms of dominant plant species were examined by using numerical classification and ordination methods. Fifty samples were first classified into nine community types and then into three succession stages. The three succession stages occurred about 9–13, 13–102, and 110–400 years ago, respectively. The earliest succession stage contained the association ofArenaria delavayi +Meconopsis horridula. The middle stage contained the associations ofArenaria delavayi + Kobresia fragilis,Carex capilliformis +Polygonum macrophyllum,Carex kansuensis, and alsoPedicularis rupicola. The last stage included the associations ofKobresia fragilis + Carex capilliformis,Kobresia fragilis,Kobresia fragilis+Ligusticum rechingerana, andKobresia fragilis + Ligusticum sikiangense. The tendency of the succession was from bare land to sparse vegetation and then to alpine meadow. In addition, three modes of dispersal were observed, namely, anemochory, mammalichory, and myrmecochory. The dispersal modes of dominant species in plant succession process were evolved from anemochory to zoochory.

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Catelli, Marika, Angelica Di Domenico, Carlo Mina e Monica Treppiedi. "Alla scoperta dei numeri che ci circondano". Didattica della matematica. Dalla ricerca alle pratiche d’aula, n. 11 (18 maggio 2022): 69–94. http://dx.doi.org/10.33683/ddm.22.11.4.

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L’articolo presenta dei percorsi didattici finalizzati all’apprendimento numerico in prima elementare, attraverso la ricerca e la conoscenza dei numeri con cui i bambini si confrontano nella quotidianità. I percorsi sono incentrati su attività di scoperta, di stampo laboratoriale e ludico, che hanno la finalità di promuovere le competenze numeriche di base, fondamentali per questo anno scolastico, proponendo anche sviluppi per ampliare e consolidare tali apprendimenti anche negli anni scolastici successivi. Per ogni percorso, vengono presentati alcuni possibili legami con i materiali creati all’interno del progetto MaMa – Matematica per la scuola elementare, che possono aiutare il docente per la progettazione di tali percorsi, consentendo di alternare attività di scoperta, concrete e manipolative, con momenti di riflessione e allenamento.

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CHERRUAULT, Y. "Some numerical methods for resolution of non-linear integral equations". MAUSAM 36, n. 3 (6 aprile 2022): 319–22. http://dx.doi.org/10.54302/mausam.v36i3.1924.

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We suggest several methods which bring back the resolution of non-linear integral equations to a succession of linear integral equations or to a linear algebraic system. All these methods have been tested numerically.

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Blajer, W. "Aircraft program motion along a predetermined trajectory Part II. Numerical simulation with application of spline functions to trajectory definitions". Aeronautical Journal 94, n. 932 (febbraio 1990): 53–58. http://dx.doi.org/10.1017/s0001924000022430.

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Aspects of numerical simulation of aircraft program flight along a predetermined trajectory are presented. An emphasis is laid on the problem of describing the required trajectory by means of a succession of defined points. A spline function method is used for interpolation and smoothing routines. Some numerical illustrations of aircraft trajectory flight simulation (only planar motion) are demonstrated and discussed.

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Yu, Andy, G. T. Lumpkin, Ritch L. Sorenson e Keith H. Brigham. "The Landscape of Family Business Outcomes". Family Business Review 25, n. 1 (12 dicembre 2011): 33–57. http://dx.doi.org/10.1177/0894486511430329.

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To promote theoretical development in family business research, this research identified 327 dependent/outcome variables used in 257 empirical family business studies in 1998-2009. In four studies, the authors categorized outcome variables, developed a numerical taxonomy with seven clusters (performance, strategy, social and economic impact, governance, succession, family business roles, and family dynamics) plotted along two dimensions (business–family and short-term–long-term), validated their research, and identified missing outcome variables and variables that deserve more attention. Experts agree that family business roles, succession, and family dynamics make the family business domain unique and that noneconomic performance and family-specific topics deserve more attention.

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Torres Montes de Oca, Carlos Alberto, José Eduardo Rosas Valencia e Oswaldo Aldair Pérez Jarquín. "Numerical-vector succession for the graphic structural analysis of masonry historic buildings with arches and symmetrical systems". Revista ALCONPAT 14, n. 2 (15 maggio 2024): 191–210. http://dx.doi.org/10.21041/ra.v14i2.717.

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Many historic buildings have symmetry in their geometric configuration. The objective of this research is to denote the application of numerical-vector succession in the structural analysis of historical masonry buildings, with arches and symmetrical systems, including mathematical processes in ancient graphic analysis, emphasizing the importance of loads in the structural stability. We based the analysis on three fundamental stages: recognition of the construction system of the heritage object, geometric discretization of the system and vector analysis under different physical considerations. Hence, the thrust lines are affected by the loads, boundary conditions and history of structural behaviour. Numerical and computational tools offer faster and more accurate graphic analysis processes. Many historic buildings have symmetry in their geometric configuration. The objective of this research is to denote the application of numerical-vector succession in the structural analysis of historical masonry buildings, with arches and symmetrical systems, including mathematical processes in ancient graphic analysis, emphasizing the importance of loads in the structural stability. We based the analysis on three fundamental stages: recognition of the construction system of the heritage object, geometric discretization of the system and vector analysis under different physical considerations. Hence, the thrust lines are affected by the loads, boundary conditions and history of structural behaviour. Numerical and computational tools offer faster and more accurate graphic analysis processes.

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Ding, Xuesong, Tristan Salles, Nicolas Flament e Patrice Rey. "Quantitative stratigraphic analysis in a source-to-sink numerical framework". Geoscientific Model Development 12, n. 6 (28 giugno 2019): 2571–85. http://dx.doi.org/10.5194/gmd-12-2571-2019.

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Abstract. The sedimentary architecture at continental margins reflects the interplay between the rate of change of accommodation creation (δA) and the rate of change of sediment supply (δS). Stratigraphic interpretation increasingly focuses on understanding the link between deposition patterns and changes in δA∕δS, with an attempt to reconstruct the contributing factors. Here, we use the landscape modelling code pyBadlands to (1) investigate the development of stratigraphic sequences in a source-to-sink context; (2) assess the respective performance of two well-established stratigraphic interpretation techniques: the trajectory analysis method and the accommodation succession method; and (3) propose quantitative stratigraphic interpretations based on those two techniques. In contrast to most stratigraphic forward models (SFMs), pyBadlands provides self-consistent sediment supply to basin margins as it simulates erosion, sediment transport and deposition in a source-to-sink context. We present a generic case of landscape evolution that takes into account periodic sea level variations and passive margin thermal subsidence over 30 million years, under uniform rainfall. A set of post-processing tools are provided to analyse the predicted stratigraphic architecture. We first reconstruct the temporal evolution of the depositional cycles and identify key stratigraphic surfaces based on observations of stratal geometries and facies relationships, which we use for comparison to stratigraphic interpretations. We then apply both the trajectory analysis and the accommodation succession methods to manually map key stratigraphic surfaces and define sequence units on the final model output. Finally, we calculate shoreline and shelf-edge trajectories, the temporal evolution of changes in relative sea level (proxy for δA) and sedimentation rate (proxy for δS) at the shoreline, and automatically produce stratigraphic interpretations. Our results suggest that the analysis of the presented model is more robust with the accommodation succession method than with the trajectory analysis method. Stratigraphic analysis based on manually extracted shoreline and shelf-edge trajectory requires calibrations of time-dependent processes such as thermal subsidence or additional constraints from stratal terminations to obtain reliable interpretations. The 3-D stratigraphic analysis of the presented model reveals small lateral variations of sequence formations. Our work provides an efficient and flexible quantitative sequence stratigraphic framework to evaluate the main drivers (climate, sea level and tectonics) controlling sedimentary architectures and investigate their respective roles in sedimentary basin development.

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Li, Ying, Gui Zhang Zhao, Lei Zeng e Cun Liang Wang. "Vegetation-Groundwater Relationship Model for Subei Lake Watershed and Prediction of Vegetation Succession Rules under Exploitation". Advanced Materials Research 518-523 (maggio 2012): 4315–20. http://dx.doi.org/10.4028/www.scientific.net/amr.518-523.4315.

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Located in an arid and semi-arid region with low rainfall and high evaporation, the Subei Lake watershed has fragile ecological environment; the impact of groundwater level recession on vegetation ecology is the key problem for the exploitation and utilization of groundwater resource in this region. In this paper, a succession model for vegetation and burial depth of groundwater level was constructed through field survey, and was used along with numeric simulation to predict the change in burial depth of groundwater level in the study area under exploitation and to analyze and predict the vegetation succession rules and processes. It is believed from the study that, while groundwater level falls constantly, the burial depth of groundwater level will increase gradually, and succession will occur gradually from aquatic vegetation to mesophytic and xerophytic vegetations, from Carex L. and Iris ensata Thunb shoaly lands to Achnatherum splendens shoaly lands, from Salix psammophila shrubs to Artemisia desterorum Spreng shrubs, and from Populus simonii to Salix matsudana.

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Xie, Xizhuang, e Meixiang Chen. "Global stability of a tridiagonal competition model with seasonal succession". Mathematical Biosciences and Engineering 20, n. 4 (2023): 6062–83. http://dx.doi.org/10.3934/mbe.2023262.

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<abstract><p>In this paper, we investigate a tridiagonal three-species competition model with seasonal succession. The Floquet multipliers of all nonnegative periodic solutions of such a time-periodic system are estimated via the stability analysis of equilibria. Together with the Brouwer degree theory, sufficient conditions for existence and uniqueness of the positive periodic solution are given. We further obtain the global dynamics of coexistence and extinction for three competing species in this periodically forced environment. Finally, some numerical examples are presented to illustrate the effectiveness of our theoretical results.</p></abstract>

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Iqbal, Naveed, Muhammad Tajammal Chughtai e Nehad Ali Shah. "Numerical simulation of fractional-order two-dimensional Helmholtz equations". AIMS Mathematics 8, n. 6 (2023): 13205–18. http://dx.doi.org/10.3934/math.2023667.

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<abstract><p>In this paper, we investigate the exact solutions of several fractional-order Helmholtz equations using the homotopy perturbation transform method. We specify sufficient requirements for its convergence and provide error estimations. The homotopy perturbation transform method yields a quickly converging succession of solutions. Solutions for various fractional space derivatives are compared to present approaches and explained using figures. Appropriate parameter selection produces approximations identical to the exact answer. Test examples are provided to demonstrate the proposed approach's precision and competence. The results demonstrate that our system is appealing, user-friendly, dependable, and highly effective.</p></abstract>

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Abd, Nada, e Shatha Salman. "The Similarity Between Two DNA Successions by Proposed Distance Estimations". International Journal of Mathematics and Computer Science 20, n. 1 (12 luglio 2024): 67–78. http://dx.doi.org/10.69793/ijmcs/01.2025/shatha.

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The specific growth requirement for normal growth is nuclear tolerance called helical DNA due to a wide range of cells and is also known to be associated with special harvesting genetics. The aim of this research is to study the similarity between my series and consciousness. The control carried out in our current review is on the chains that control the body of humans, orangutans and gorillas. The graph hypothesis was used to examine genetic association and is a numerical approach. This methodology commenced by regarding the DNA clusters of each element as a coordinate graph. Hence, the proximity network was defined, and the network vector was generated for each graph. Distance estimations like correlation, Euclidean, and cosine can be utilized to detect the degree of similarity between two sets of DNA using vectors.

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Ha, Kyoung-Sook, e Sa-Whae Gu. "Literary Review Lyrics of the New Modern Age [Numerical song(數字歌)]and the Succession of Numerical Songs". EASTERN CLASSIC STUDIES 43 (31 agosto 2020): 213–38. http://dx.doi.org/10.25086/hsdy.2020.43.213.

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McDougall, I., e R. T. Watkins. "Potassium–argon ages of volcanic rocks from northeast of Lake Turkana, northern Kenya". Geological Magazine 125, n. 1 (gennaio 1988): 15–23. http://dx.doi.org/10.1017/s001675680000933x.

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AbstractThe Asille Group, a 1500 m succession comprising dominantly basaltic lavas but with interbedded sediments and silicic volcanics, lies unconformably upon metamorphosed basement northeast of Lake Turkana. Concordant K–Ar ages on alkali feldspars from pantelleritic units in the succession show that the Langaria Formation erupted 26.9±0.3 Ma ago in late Oligocene time, that Gum Dura Formation volcanism occurred at 15.8±0.2 Ma (early Miocene), and that there was widespread middle Miocene silicic volcanism at 13.0±0.3 Ma. Younger basaltic volcanism producing the flood lavas of the Gombe Group commenced at least 6.16±0.09 Ma ago in late Miocene time. These results, based upon 20 K–Ar age determinations, provide good numerical age control for much of the sequence developed within a little known sector of the Eastern Rift of Africa between the Ethiopian and Kenyan domes.

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Timmermann, Axel, Kyung-Sook Yun, Pasquale Raia, Jiaoyang Ruan, Alessandro Mondanaro, Elke Zeller, Christoph Zollikofer et al. "Climate effects on archaic human habitats and species successions". Nature 604, n. 7906 (13 aprile 2022): 495–501. http://dx.doi.org/10.1038/s41586-022-04600-9.

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AbstractIt has long been believed that climate shifts during the last 2 million years had a pivotal role in the evolution of our genus Homo1–3. However, given the limited number of representative palaeo-climate datasets from regions of anthropological interest, it has remained challenging to quantify this linkage. Here, we use an unprecedented transient Pleistocene coupled general circulation model simulation in combination with an extensive compilation of fossil and archaeological records to study the spatiotemporal habitat suitability for five hominin species over the past 2 million years. We show that astronomically forced changes in temperature, rainfall and terrestrial net primary production had a major impact on the observed distributions of these species. During the Early Pleistocene, hominins settled primarily in environments with weak orbital-scale climate variability. This behaviour changed substantially after the mid-Pleistocene transition, when archaic humans became global wanderers who adapted to a wide range of spatial climatic gradients. Analysis of the simulated hominin habitat overlap from approximately 300–400 thousand years ago further suggests that antiphased climate disruptions in southern Africa and Eurasia contributed to the evolutionary transformation of Homo heidelbergensis populations into Homo sapiens and Neanderthals, respectively. Our robust numerical simulations of climate-induced habitat changes provide a framework to test hypotheses on our human origin.

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DONG, S., e X. ZHENG. "Direct numerical simulation of spiral turbulence". Journal of Fluid Mechanics 668 (13 dicembre 2010): 150–73. http://dx.doi.org/10.1017/s002211201000460x.

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In this paper, we present results of three-dimensional direct numerical simulations of the spiral turbulence phenomenon in a range of moderate Reynolds numbers, in which alternating intertwined helical bands of turbulent and laminar fluids co-exist and propagate between two counter-rotating concentric cylinders. We show that the turbulent spiral is comprised of numerous small-scale azimuthally elongated vortices, which align into and collectively form the barber-pole-like pattern. The domain occupied by such vortices in a plane normal to the cylinder axis resembles a ‘crescent moon’, a shape made well known by Van Atta with his experiments in the 1960s. The time-averaged mean velocity of spiral turbulence is characterized in the radial–axial plane by two layers of axial flows of opposite directions. We also observe that, as the Reynolds number increases, the transition from spiral turbulence to featureless turbulence does not occur simultaneously in the whole domain, but progresses in succession from the inner cylinder towards the outer cylinder. Certain aspects pertaining to the dynamics and statistics of spiral turbulence and issues pertaining to the simulation are discussed.

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Zhuravlev, Andrey. "Numerical modelling of primary bioproductivity of the Palaeozoic pelagic ecosystems". Vestnik of geosciences, n. 8 (10 novembre 2022): 38–43. http://dx.doi.org/10.19110/geov.2022.8.4.

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The article considers an approach to the reconstruction of the bioproductivity of Palaeozoic pelagic ecosystems based on the numeric modelling of the carbon isotope fractionation. The model uses information on the carbon dioxide content in atmosphere, water temperature, and carbon isotopic composition of carbonates and conodont elements. The developed model is tested on the material from the Upper Devonian — Lower Carboniferous of the northern Cis-Urals (successions of carbonate platform and slope of intrashelf depression). It allows reconstructing of the primary productivity of the Palaeozoic pelagic ecosystems and their dynamics on the basis of limited data. The results of the modelling are considered as rather qualitative than quantitative. The carbon isotope composition of total organic carbon was used for controlling the quality of the model.

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Zhang, Zizhen, e Limin Song. "Dynamics of a Computer Virus Propagation Model with Delays and Graded Infection Rate". Advances in Mathematical Physics 2017 (2017): 1–13. http://dx.doi.org/10.1155/2017/4514935.

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A four-compartment computer virus propagation model with two delays and graded infection rate is investigated in this paper. The critical values where a Hopf bifurcation occurs are obtained by analyzing the distribution of eigenvalues of the corresponding characteristic equation. In succession, direction and stability of the Hopf bifurcation when the two delays are not equal are determined by using normal form theory and center manifold theorem. Finally, some numerical simulations are also carried out to justify the obtained theoretical results.

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Hsieh, Tung-Yu, Chun-Jheng Yang, Feng Li e Chyi-Rong Chiou. "Numerical Ecology and Social Network Analysis of the Forest Community in the Lienhuachih Area of Taiwan". Diversity 15, n. 1 (3 gennaio 2023): 60. http://dx.doi.org/10.3390/d15010060.

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In this study, the integration of useful statistical methods from different disciplines for analyzing the forest community of the Lienhuachih area of central Taiwan was attempted. We employed a seriated heat map to confirm the presence of multiple community patterns in the area and used the gap statistics and a clustplot to confirm the number and structure of the patterns, respectively. A minimum spanning tree was used to display a succession series among the quadrats, and Renyi diversity was used to indicate the species composition of these patterns. The results confirmed the existence of six patterns with different biodiversity structures in which pattern C was the succession prototype of the local community patterns. Next, we used the patterns as nodes of a social network to perform bipartite network analysis. The results showed that a community network consisted of 108 taxa and six syntaxa. The syntaxa were highly vulnerable to extinction; therefore, the optimal conservation strategy for local species would be to first protect the syntaxa. The random forest method and bipartite modularity were used to analyze the dominant characteristic species of the six syntaxa. The results showed that these two methods are useful for detecting characteristic species of the syntaxa. Therefore, this study proposed a new nomenclature system, namely the Mathematic Code of Syntaxonomic Nomenclature, to support the results of numerical vegetation analysis. Finally, the potential for an apparently competitive network was examined, the role of an apparently competitive network in the local structuring community was explored, and six new associations in the Lienhuachih area were described.

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Hollohan, Brendan T., Patrick E. Dabinett e John A. Gow. "Bacterial succession during biodegradation of the kelp Alaria esculenta (L.) Greville". Canadian Journal of Microbiology 32, n. 6 (1 giugno 1986): 505–12. http://dx.doi.org/10.1139/m86-092.

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In northern latitudes large quantities of kelp can be dislodged by ice scouring during spring and early summer. Quantities of kelp are then available to enter the detrital food chain. Bacterial succession, on decaying fronds of the brown macroalga Alaria esculenta, was investigated. There was a loss of approximately 70% of the algal mass during late spring and summer. During this time Vibrio dominated the heterotrophic bacterial population. Species of marine Pseudomonas comprised about 10–30% of the population, depending upon the occasion of isolation. By using numerical taxonomy it was shown that the strains of Vibrio formed distinct and separate clusters according to the occasion on which they were isolated. Among Pseudomonas strains a more gradual change was observed, but by the time of the final isolation, the Pseudomonas strains were different from those isolated at the beginning of the study. The results of characterization tests showed that strains from all clusters were suited to growth on substrates which are components of brown algae and that a succession of bacterial species, of more than one genus and family, occurred during the decay process.

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Yokoyama, Yujiro, Tomoyuji Mizukoshi, Itsuo Ishigami e Tateo Usui. "Numerical Analysis and Control of Gas Carburizing under Changes in Gas Compositions". Materials Science Forum 522-523 (agosto 2006): 589–94. http://dx.doi.org/10.4028/www.scientific.net/msf.522-523.589.

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Low carbon steel, S15CK, was carburized at 1203K up to 12.93ks in a commercial furnace where RX gas converted from propane was employed as carrier gas. Gas compositions in the furnace were changed intentionally; consequently carbon potential changed from 0.8 to 1.2 mass%. The carbon content profiles were determined by a succession of grindings and carbon analyses of the ground surfaces with a vacuum type emission spectrometer. A mathematical model for calculation of carbon content profiles is proposed to describe carburizing behavior under time-variant gas compositions in a furnace. The calculated profiles were in good agreement with the experimental ones except the surface and its vicinity. This result indicates that the present model can be applied to gas carburizing in the furnace where gas compositions were changed.

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Derekx, Q., P. Bacchin, D. Veyret, K. Glucina e P. Moulin. "Simulation of particle capture in a microfiltration membrane". Water Science and Technology 64, n. 6 (1 settembre 2011): 1368–73. http://dx.doi.org/10.2166/wst.2011.349.

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The present study takes an interest in the description of the fouling mechanisms by a numerical approach at the microscopic scale. At first, an X-ray tomography has enabled the modelling of the membrane structure for the numerical simulations. Next, for different particle size, a same volume of particles has been sent in the modelled membrane and the final permeability has been computed. Thus, the influence of the particle size on the fouling has been seen. An observation of the particles penetration in the membrane has been realised to detail this influence. The Hermia relations were used in order to determinate the predominant fouling mechanism or the succession of predominant fouling mechanisms. But, without an accurate calculation of the first derivative, it is not possible to define cleanly the predominant fouling mechanism for a low filtered volume. Nevertheless, the perspectives of the local approach with the numerical simulation seem interesting.

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Yakovlev, P. A. "Fast trie-based method for multiple pairwise sequence alignment". Доклады Академии наук 484, n. 4 (5 maggio 2019): 401–4. http://dx.doi.org/10.31857/s0869-56524844401-404.

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A method for efficient comparison of a symbol sequence with all strings of a set is presented, which performs considerably faster than the naive enumeration of comparisons with all strings in succession. The procedure is accelerated by applying an original algorithm combining a prefix tree and a standard dynamic programming algorithm searching for the edit distance (Levenshtein distance) between strings. The efficiency of the method is confirmed by numerical experiments with arrays consisting of tens of millions of biological sequences of variable domains of monoclonal antibodies.

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Porta, P. A., L. M. Hoffer, H. Grassi e G. L. Lippi. "Control of Turn-On in Class B Lasers". International Journal of Bifurcation and Chaos 08, n. 09 (settembre 1998): 1811–19. http://dx.doi.org/10.1142/s0218127498001522.

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A very simple technique, which uses a succession of two different but constant levels in the pump parameter, is shown to be quite effective in controlling the turn-on transient of a class B laser. In particular,a drastic reduction in the delay time, as well as a lowering of the intensity overshoot under suitable conditions, has been observed both in numerical simulations and in experiments on a CO 2 laser. Such a straightforward, nonfeedback technique may have very promising applications in the realm of communications.

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McSorley, Robert. "Ecology of the dorylaimid omnivore genera Aporcelaimellus, Eudorylaimus and Mesodorylaimus". Nematology 14, n. 6 (7 luglio 2012): 645–63. http://dx.doi.org/10.1163/156854112x651168.

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Abstract (sommario):

Eudorylaimus, Aporcelaimellus and Mesodorylaimus are dominant members of the omnivorous nematode fauna in Florida, USA. Ecological studies that included numerical data on these genera were reviewed to determine key aspects of their ecology and behaviour. These three genera were also the dominant omnivores in many parts of Europe and often occurred together. Multiple species within genera may be present in samples as well. Although results varied with habitat, these omnivores were present in nearly all stages of succession but often reached their greatest numbers in later stages of succession such as old-growth forests. They also showed remarkable adaptation to extreme environments, including Antarctic habitats, dune sands and temperate sites without vegetation. They were found in a variety of soil types but limited by soil pH < 4.0. Compared with other nematode taxa, they were among the genera most sensitive to moisture levels in sandy soils and to pollution by heavy metals. Some reports also indicated adverse impacts from inorganic fertilisers and other agrichemicals. Much remains unknown about the ecology of these common nematodes, which are widely distributed in soil ecosystems.

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Gniadek, Jacek, Jacek M. Pijanowski e Mateusz Śmigielski. "Impact of the forest succession on efficiency of the arable land production". Journal of Water and Land Development 34, n. 1 (26 settembre 2017): 131–38. http://dx.doi.org/10.1515/jwld-2017-0046.

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Abstract The paper presents the studies involving analysis of changes in shape of parcels of arable land under the influence of forest succession. The object of the research is the village Grębosze located in Świętokrzyskie voivodeship. The study material will cover all arable land existing in the studied village. The source of data were numerical registry maps from 1998 and 2013. The basic element of research, enabling comparison of changes in the efficiency of the production process are continuous parts of the parcels covered by one form of use. In the course of the output data processing and determination of the necessary technical parameters for the tested surface elements, the specialized tools and statistics were used. The studies were related to the evaluation of formation of these surface structures on the basis of their shape meter in the form of the so-called costs of cultivation. The obtained results make it possible to tell, to what extent the changes resulting from the consequences of the secondary forest succession influence the process of cultivation of neighbouring arable land.

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32

Di Stefano, Agata, Natale Maria D’Andrea, Salvatore Distefano, Salvatore Urso, Laura Borzì, Niccolò Baldassini e Viviana Barbagallo. "Calcareous Nannofossil Biostratigraphy and Biochronology at ODP Site 1123 (Offshore New Zealand): A Reference Section for the Last 20 Myr in the Southern Ocean". Journal of Marine Science and Engineering 11, n. 2 (13 febbraio 2023): 408. http://dx.doi.org/10.3390/jmse11020408.

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Abstract (sommario):

The quantitative analysis of the calcareous nannofossil content yield in the 600 m thick succession drilled at ODP Site 1123 (offshore New Zealand), considered as a reference section for the Southern Ocean region, allowed the recognition of 43 bioevents distributed along the last 20 Myr. The correlation with the excellent magnetostratigraphic record resulted in the attribution of numerical ages for the position of the detected horizons. Many of the marker species used in previous zonation were detected also at ODP Site 1123, but others revealed to be absent or of scarce applicability. On the other hand, the good applicability of additional events was verified and proved to be useful for the biostratigraphic subdivision and correlation. The obtained average bio- and chronostratigraphic resolution is about 0.6 Myr along the whole section, which increases to about 0.3 in the Pliocene–Holocene time interval. The final result is a detailed southern mid-to-high latitude nannofossil biochronology for the last 20 Myr, which confirms that the ODP Site 1123 succession represents a reference section for the Southern Ocean.

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Stephan, Jean, Julien Barhoun, Elias Maatouk, Bruno Foucault e Samir Safi. "Syntaxonomy of open oak forests on basalt formations in north Lebanon". Lebanese Science Journal 20, n. 3 (27 dicembre 2019): 391–412. http://dx.doi.org/10.22453/lsj-020.3.391-412.

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This phytosociological study of the Dreib Region in Akkar-Lebanonis the first on basaltic bedrockin Lebanon. Thesynusial methods isused and compared bynumerical classification. The latter shows satisfactory results when compared to the synusial manual classification. The followingplant associations are defined:Quercetum veneris–ithaburensis, Calicotomo villosae –Rhamnetum punctati, Eryngio cretici –Echietum angustifolii and Sileno aegyptiacae –Isatidetum lusitanicae.Consequently, the alliance Quercion ithaburensi is stated for the first time in Lebanon. Vegetationseries for progressive and regressive successions are also produced. Further relevés are required to consolidate additional associations that are depicted from both synusial and numerical vegetation classifications.

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Sun, Ke, Zhongfeng Qiu, Yijun He, Wei Fan e Zexun Wei. "Succession of causative species during spring blooms in the East China Sea: coupled biophysical numerical modeling". Acta Oceanologica Sinica 35, n. 12 (dicembre 2016): 1–11. http://dx.doi.org/10.1007/s13131-016-0964-0.

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35

Hasanah, Putri Sholehah, Bistari Bistari e Dian Ahmad BS. "Kemampuan Pemahaman Matematis Siswa dalam Menyelesaikan Soal Cerita Dikaji dari Sikap Ilmiah". AS-SABIQUN 4, n. 4 (1 settembre 2022): 1043–57. http://dx.doi.org/10.36088/assabiqun.v4i4.2142.

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Abstract (sommario):

This review plans to depict and dissect the understudies' numerical comprehension capacity in taking care of story issues contemplated from the logical disposition on the material of arrangements and series in class XI IPA 3 SMA Negeri 9 Pontianak. This exploration is a subjective elucidating study. Information on understudies' numerical comprehension capacities were gathered through tests and meetings. Information on understudies' logical perspectives were gathered through perception and meetings. The information sources were three understudies who were chosen as examination subjects, specifically: one understudy with the capacity to see numerically on marks of interpretation, translation and extrapolation. The test is as 7 story questions connected with number-crunching successions and series material and is done in 60 minutes or less. Perceptions were made to decide the logical demeanor of understudies during the test. Interviews were led to figure out additional about understudies' logical perspectives and understudies' numerical comprehension capacities in view of experimental outcomes. The outcomes showed: 1) understudies' numerical comprehension capacity in the medium classification interpretation marker had a logical mentality including the adequate class; 2) understudies' numerical comprehension capacity in the medium classification translation pointer has a logical disposition including the adequate classification; 3) understudies' numerical comprehension capacity in the low classification extrapolation marker has a logical demeanor including the horrible classification.

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36

Falcone, Gaetano, Giuseppe Naso, Federico Mori, Amerigo Mendicelli, Gianluca Acunzo, Edoardo Peronace e Massimiliano Moscatelli. "Effect of Base Conditions in One-Dimensional Numerical Simulation of Seismic Site Response: A Technical Note for Best Practice". GeoHazards 2, n. 4 (18 dicembre 2021): 430–41. http://dx.doi.org/10.3390/geohazards2040024.

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The effects induced by the choice of numerical base conditions for evaluating local seismic response are investigated in this technical note, aiming to provide guidelines for professional applications. A numerical modelling of the seismic site response is presented, assuming a one-dimensional scheme. At first, with reference to the case of a homogeneous soil layer overlying a half-space, two different types of numerical base conditions, named rigid and elastic, were adopted to analyse the seismic site response. Then, geological setting, physical and mechanical properties were selected from Italian case studies. In detail, the following stratigraphic successions were considered: shallow layer 1 (shear wave velocity, VS, equal to 400 m/s), layer 2 (VS equal to 600 m/s) and layer 3 (VS equal to 800 m/s). In addition, real signals were retrieved from the web site of the Italian accelerometric strong motion network. Rigid and elastic base conditions were adopted to estimate the ground motion modifications of the reference signals. The results are presented in terms of amplification factors (i.e., ratio of integral quantities referred to free-field and reference response spectra) and are compared between the adopted numerical models.

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37

Leoveanu, Ioan Sorin, e Gheorghe Zgura. "Modelling the Heat and Fluid Flow in the Welded Pool from High Power Arc Sources". Materials Science Forum 580-582 (giugno 2008): 443–46. http://dx.doi.org/10.4028/www.scientific.net/msf.580-582.443.

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The paper proposes a numerical method for analyzing the complex phenomena’s that appear in the case of keyholes welded pool geometry. Present model consist in a succession of analyses steps, needed to solve the interaction between the liquid/solid, liquid/protection gaze and liquid/MHD welded arc for arc welding, or electrons, or electromagnetic waves. The liquid/solid geometry result by dissipation of the welding power source in a matrix of many point sources. This process gives a first approximation of temperature fields and a good approximation of the digit 3D position, and information about the vaporization area.

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38

Liu, Wei, e Yaolin Jiang. "Analysis of a Delayed Predator–Prey System with Harvesting". International Journal of Nonlinear Sciences and Numerical Simulation 19, n. 3-4 (26 giugno 2018): 335–49. http://dx.doi.org/10.1515/ijnsns-2017-0094.

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AbstractThis article is concerned with a Leslie–Gower predator–prey system with the predator being harvested and the prey having a delay due to the gestation of prey species. By regarding the gestation delay as a bifurcation parameter, we first derive some sufficient conditions on the stability of positive equilibrium point and the existence of Hopf bifurcations basing on the local parametrization method for differential-algebra system. In succession, we also investigate the direction of Hopf bifurcations and the stability of bifurcating periodic solutions on the center manifold by employing the center manifold reduction for functional differential equations. Finally, to verify our theoretical predictions, several numerical simulations are given.

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39

Huang, Edward, Mourad Oudich, Hyeonu Heo e Yun Jing. "Ultra-stiff and ultra-light architected metamaterial for vibration mitigation". Journal of the Acoustical Society of America 152, n. 4 (ottobre 2022): A170. http://dx.doi.org/10.1121/10.0015918.

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Abstract (sommario):

We designed, fabricated, and experimentally validated an architected mechanical metamaterial vibration shielding while ensuring high effective stiffness with low density. The structure is made of a periodic succession of octet truss units with alternating circular strut diameters. The octet truss endows the meta-structure with a high effective stiffness and a low effective density, while alternating the units with different struts radii enables the opening of a wide band-gap for elastic waves. Samples were 3D printed and experimentally validated using a shaker and accelerometer. Unidirectional compression test was also performed to characterize the mechanical properties of the metamaterial. The results are in good agreement with the numerical prediction.

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40

Guo, Hong Wei, Hong Zheng e Wei Li. "Implement of Ameliorated ACM Element in Numerical Manifold Space for Tackling Kirchhoff Plate Bending Problems". Applied Mechanics and Materials 638-640 (settembre 2014): 1710–15. http://dx.doi.org/10.4028/www.scientific.net/amm.638-640.1710.

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Abstract (sommario):

Ab ridging the chasm between the prevalent ly employed continuum methods (e.g. FEM) and discontinuum methods (e.g. DDA) ,the numerical manifold (NNM) ,which utilizes two covers, namely the mathematical cover and physical cover , has evinced various advantages in solving solid mechanic al issues. The forth-order partial elliptic differential equation governing Kirchhoff plate bending makes it arduous to establish the -regular Lagrangian partition of unity ,nevertheless, this study renders a modified conforming ACM manifold element , irrespective of accreting its cover degrees, to resolve the fourth-order problems. In tandem with the forming of the finite element cover system that erected on r ectangular mesh es , a succession of n umerical manifold formulas are derived on grounds of the minimum potential energy principle and the displacement boundary conditions are executed by penalty function methods. The numerical example elucidates that , compared with the orthodox ACM element , the proposed methods bespeak the accuracy and precipitating convergence of the NMM .

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41

He, Xi, e Russell A. Wright. "An Experimental Study of Piscivore–Planktivore Interactions: Population and Community Responses to Predation". Canadian Journal of Fisheries and Aquatic Sciences 49, n. 6 (1 giugno 1992): 1176–83. http://dx.doi.org/10.1139/f92-132.

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The population dynamics and behavior of an assemblage of fishes in a small bog lake were studied in a succession of whole-lake manipulations of piscivores. Total prey fish biomass declined after the addition of northern pike (Esox lucius). This decline was the result of emigration by cyprinid prey and consumption by northern pike. The emigration response of the cyprinids was dependent on cyprinid density. At high prey fish biomass, a significant portion of the loss in biomass was the result of emigration; this was not the case at low prey fish biomass. The prey fish community shifted from small-bodied soft-rayed species prior to the introduction of northern pike to species with spines or deep bodies after predator stocking. The community response was analyzed at four levels of numerical resolution: absolute, relative, and ranked abundance and presence–absence of prey species. High numerical resolution captured the dynamic short-term population responses to predation and suggests unstable community structure.

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42

Zhou, Zheng-Xi, Ren-Cheng Yu e Ming-Jiang Zhou. "Seasonal succession of microalgal blooms from diatoms to dinoflagellates in the East China Sea: A numerical simulation study". Ecological Modelling 360 (settembre 2017): 150–62. http://dx.doi.org/10.1016/j.ecolmodel.2017.06.027.

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43

Zhu, Liangsheng, e Qing Wang. "Numerical Mesocosm Experimental Study on Harmful Algal Blooms of Two Algal Species in the East China Sea". Mathematical Problems in Engineering 2015 (2015): 1–8. http://dx.doi.org/10.1155/2015/169860.

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Abstract (sommario):

From the results of algal culture and mesocosm experiments, a numerical mesocosm experiment is designed that accounts for the effect of the marine environment (sea currents, nutrient levels, and temperature) on the harmful algal bloom (HAB) processes ofSkeletonema costatumandProrocentrum donghaiense, two of the most frequent HAB-associated species in the East China Sea. Physical and ecological environment of the waters is simulated numerically by applying a hydrodynamic-ecological-one-way-coupled marine culture box model, which is semienclosed. The algal growth rate is digitalized by a temperature-factor-optimization Droop equation. A 90-mode-day numerical mesocosm experiment for the above two species is conducted. The species were found to alternately trigger algal blooms in the experimental waters, replicating the population succession phenomenon observed in the field and confirming that the two HAB species compete for nutrients. Deductively, the numerical result shows that both the Taiwan Warm Current and the eutrophication in the adjacent water of the Yangtze River Estuary contribute to the northward movement of algal concentration centers during HAB and also suggests that the lack of nutritious supplements in the open sea limits HAB occurrences in coastal waters.

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44

Runtz, M. W. P., e Stewart B. Peck. "THE BEETLE FAUNA OF A MATURE SPRUCE–SPHAGNUM BOG, ALGONQUIN PARK, ONTARIO; ECOLOGICAL IMPLICATIONS OF THE SPECIES COMPOSITION". Memoirs of the Entomological Society of Canada 126, S169 (1994): 161–71. http://dx.doi.org/10.4039/entm126169161-1.

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AbstractThe beetle (Coleoptera) fauna of a black spruce [Picea mariana (Mill.) BSP] – tamarack [Larix laricina (DuRoi) K. Koch] – Sphagnum bog in Algonquin Provincial Park, Ontario, was sampled from early June to mid-August with yellow pan traps and emergence traps. The yield was 5734 beetles, in 30 families. Ptiliidae was the most numerically abundant and Staphylinidae was the most taxonomically diverse. Carabidae was second in diversity and third in numerical abundance. The abundance and ecological implications of some individual species are discussed. Few of the species are bog-specific. The faunal composition suggests that the bog is in a late-succession phase and that most of the beetle species are derived from adjacent habitats.

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Audemar, Vassanti, Thomas Podgorski e Gwennou Coupier. "Rheology and structure of a suspension of deformable particles in plane Poiseuille flow". Physics of Fluids 34, n. 4 (aprile 2022): 042013. http://dx.doi.org/10.1063/5.0087378.

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Abstract (sommario):

We present an experimental study of the rheology and structure of a confined suspension of deformable particles flowing in a quasi-two-dimensional Poiseuille flow. Thanks to a precise microfluidic viscosimetry technique combined with measurements of concentration profiles, our study provides the first experimental confirmation with three-dimensional particles of a strong relationship between structuring effects and rheology, previously only reported in numerical simulations of purely two-dimensional systems. In conditions where strong structuring effects take place due to confinement, the evolution of the effective viscosity with particle concentration (here, red blood cells) shows a remarkable succession of ranges of rapid growth and plateaus that are associated with qualitative transitions in the structure of the suspension.

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46

Sellwood, J. A. "Spiral instabilities in N-body simulations – II. Emergence from noise". Monthly Notices of the Royal Astronomical Society 492, n. 3 (8 gennaio 2020): 3103–6. http://dx.doi.org/10.1093/mnras/staa034.

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ABSTRACT An earlier paper presented the potentially significant discovery that disturbances in simplified simulations of a stellar disc model that was predicted to be stable in linear theory grew to large amplitude over a long period of time. The ultimate appearance of true instabilities was attributed to non-linear scattering by a succession of collective waves excited by shot noise from the finite number of particles. The paper concluded that no finite number of particles, however large, could mimic a smooth disc. As this surprising finding has been challenged as an artefact of the numerical scheme employed, we here present a new calculation of the same model using a different grid geometry that confirms the original behaviour.

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Salles, Tristan, Jodie Pall, Jody M. Webster e Belinda Dechnik. "Exploring coral reef responses to millennial-scale climatic forcings: insights from the 1-D numerical tool pyReef-Core v1.0". Geoscientific Model Development 11, n. 6 (8 giugno 2018): 2093–110. http://dx.doi.org/10.5194/gmd-11-2093-2018.

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Abstract. Assemblages of corals characterise specific reef biozones and the environmental conditions that change spatially across a reef and with depth. Drill cores through fossil reefs record the time and depth distribution of assemblages, which captures a partial history of the vertical growth response of reefs to changing palaeoenvironmental conditions. The effects of environmental factors on reef growth are well understood on ecological timescales but are poorly constrained at centennial to geological timescales. pyReef-Core is a stratigraphic forward model designed to solve the problem of unobservable environmental processes controlling vertical reef development by simulating the physical, biological and sedimentological processes that determine vertical assemblage changes in drill cores. It models the stratigraphic development of coral reefs at centennial to millennial timescales under environmental forcing conditions including accommodation (relative sea-level upward growth), oceanic variability (flow speed, nutrients, pH and temperature), sediment input and tectonics. It also simulates competitive coral assemblage interactions using the generalised Lotka–Volterra system of equations (GLVEs) and can be used to infer the influence of environmental conditions on the zonation and vertical accretion and stratigraphic succession of coral assemblages over decadal timescales and greater. The tool can quantitatively test carbonate platform development under the influence of ecological and environmental processes and efficiently interpret vertical growth and karstification patterns observed in drill cores. We provide two realistic case studies illustrating the basic capabilities of the model and use it to reconstruct (1) the Holocene history (from 8500 years to present) of coral community responses to environmental changes and (2) the evolution of an idealised coral reef core since the last interglacial (from 140 000 years to present) under the influence of sea-level change, subsidence and karstification. We find that the model reproduces the details of the formation of existing coral reef stratigraphic sequences both in terms of assemblages succession, accretion rates and depositional thicknesses. It can be applied to estimate the impact of changing environmental conditions on growth rates and patterns under many different settings and initial conditions.

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Di Maida, P., e G. Bianchi. "Numerical Investigation of Pull-In Instability in a Micro-Switch MEMS Device through the Pseudo-Spectral Method". Modelling and Simulation in Engineering 2016 (2016): 1–6. http://dx.doi.org/10.1155/2016/8543616.

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Abstract (sommario):

A pseudo-spectral approximation is presented to solve the problem of pull-in instability in a cantilever micro-switch. As well known, pull-in instability arises when the acting force reaches a critical threshold beyond which equilibrium is no longer possible. In particular, Coulomb electrostatic force is considered, although the method can be easily generalized to account for fringe as well as Casimir effects. A numerical comparison is presented between a pseudo-spectral and a Finite Element (FE) approximation of the problem, both methods employing the same number of degrees of freedom. It is shown that the pseudo-spectral method appears more effective in accurately approximating the behavior of the cantilever near its tip. This fact is crucial to capturing the threshold voltage on the verge of pull-in. Conversely, the FE approximation presents rapid successions of attracting/repulsing regions along the cantilever, which are not restricted to the near pull-in regime.

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KLUNK, M. A., S. DASGUPTA, M. DAS, P. R. WANDER e A. DI CAPUA. "GEOCHEMICAL SPECIATION AND BATCH MODE SIMULATION IN THE CARBONATE DEPOSITIONAL ENVIRONMENTS". Periódico Tchê Química 16, n. 33 (20 marzo 2019): 736–48. http://dx.doi.org/10.52571/ptq.v16.n33.2019.751_periodico33_pgs_736_748.pdf.

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Geochemical modeling has been frequently used to understand and interpret water-rock interactions in sedimentary basins. Thermodynamic data, kinetic parameters, numerical methods, boundary history, and boundary conditions are factors affecting any geochemical modeling system. In the present study, we have attempted to establish a geochemical speciation model by comparing the interaction of formation water and carbonate rock in the carbonate depositional settings of Cambrian successions of Bachu and Tarim area. A comparative study of geochemical speciation has been performed using four different software: PHREEQCTM, GWBTM, TOUGHREACTTM, and GEODELING. GEODELING is a geochemical code simulator that we have developed, and the details are presented further in this work. All the software has been analyzed minutely, considering the distribution, mobility, and availability of chemical species in geological environments. Very similar results in speciation are observed while working with low-temperature systems. A discrepancy can be observed in the results while working with high temperatures. However, a thorough Newton-Raphson formulation, scaling of algebraic equations and master-species switching helps to reduce the possibility of failures of the numerical method used in PHREEQCTM.

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Sinnesael, Matthias, Alfredo Loi, Marie-Pierre Dabard, Thijs R. A. Vandenbroucke e Philippe Claeys. "Cyclostratigraphy of the Middle to Upper Ordovician successions of the Armorican Massif (western France) using portable X-ray fluorescence". Geochronology 4, n. 1 (16 maggio 2022): 251–67. http://dx.doi.org/10.5194/gchron-4-251-2022.

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Abstract. To expand traditional cyclostratigraphic numerical methods beyond their common technical limitations and apply them to truly deep-time archives, we need to reflect on the development of new approaches to sedimentary archives that are not traditionally targeted for cyclostratigraphic analysis but that frequently occur in the impoverished deep-time record. Siliciclastic storm-dominated shelf environments are a good example of such records. Our case study focuses on the Middle to Upper Ordovician siliciclastic successions of the Armorican Massif (western France) that are well-studied examples in terms of sedimentology and sequence stratigraphy. In addition, these sections are protected geological heritage due to the extraordinary quality of the outcrops. We therefore tested the performance of non-destructive high-resolution (centimeter-scale) portable X-ray fluorescence and natural gamma-ray analyses on an outcrop to obtain major and trace element compositions. Despite the challenging outcrop conditions in the tidal beach zone, our geochemical analyses provide useful information regarding general lithology and several specific sedimentary features such as the detection of paleo-placers or the discrimination between different types of diagenetic concretions such as nodules. Secondly, these new high-resolution data are used to experiment with the application of commonly used numerical cyclostratigraphic techniques on this siliciclastic storm-dominated shelf environment, a non-traditional sedimentological setting for cyclostratigraphic analysis. In the parts of the section with a relatively homogeneous lithology, spectral power analyses and bandpass filtering hint towards a potential astronomical imprint of some sedimentary cycles, but this needs further confirmation in the absence of more robust independent age constraints.

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