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Статті в журналах з теми "Extinction criterion":
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Gorea, Andrei, and Dov Sagi. "Natural extinction: A criterion shift phenomenon." Visual Cognition 9, no. 8 (November 2002): 913–36. http://dx.doi.org/10.1080/13506280143000638.
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Ridler-Rowe, C. J. "Extinction times for certain predator–prey processes." Journal of Applied Probability 25, no. 3 (September 1988): 612–16. http://dx.doi.org/10.2307/3213988.
Анотація:
Finiteness of mean extinction times for certain predator-prey models has been established by Hitchcock (1986) with the aid of a criterion of Reuter (1957). Using this criterion and a ‘minimisation' lemma this note shows that the mean extinction times tend to zero as the combined initial population of predators and prey becomes large.
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Ridler-Rowe, C. J. "Extinction times for certain predator–prey processes." Journal of Applied Probability 25, no. 03 (September 1988): 612–16. http://dx.doi.org/10.1017/s0021900200041310.
Анотація:
Finiteness of mean extinction times for certain predator-prey models has been established by Hitchcock (1986) with the aid of a criterion of Reuter (1957). Using this criterion and a ‘minimisation' lemma this note shows that the mean extinction times tend to zero as the combined initial population of predators and prey becomes large.
4
Shiozawa, Yuichi. "Extinction of branching symmetric α-stable processes". Journal of Applied Probability 43, № 4 (грудень 2006): 1077–90. http://dx.doi.org/10.1239/jap/1165505209.
Анотація:
We give a criterion for extinction or local extinction of branching symmetric α-stable processes in terms of the principal eigenvalue for time-changed processes of symmetric α-stable processes. Here the branching rate and the branching mechanism are spatially dependent. In particular, the branching rate is allowed to be singular with respect to the Lebesgue measure. We apply this criterion to some branching processes.
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Shiozawa, Yuichi. "Extinction of branching symmetric α-stable processes". Journal of Applied Probability 43, № 04 (грудень 2006): 1077–90. http://dx.doi.org/10.1017/s0021900200002448.
Анотація:
We give a criterion for extinction or local extinction of branching symmetric α-stable processes in terms of the principal eigenvalue for time-changed processes of symmetric α-stable processes. Here the branching rate and the branching mechanism are spatially dependent. In particular, the branching rate is allowed to be singular with respect to the Lebesgue measure. We apply this criterion to some branching processes.
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Katta, V. R., T. R. Meyer, M. S. Brown, J. R. Gord, and W. M. Roquemore. "Extinction criterion for unsteady, opposing-jet diffusion flames." Combustion and Flame 137, no. 1-2 (April 2004): 198–221. http://dx.doi.org/10.1016/j.combustflame.2004.02.004.
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Zhai, Jinan, Shangyu Zhang, and Linhua Liu. "Extinction and Independent Scattering Criterion for Clusters of Spherical Particles Embedded in Absorbing Host Media." Photonics 10, no. 7 (July 5, 2023): 782. http://dx.doi.org/10.3390/photonics10070782.
Анотація:
In practical applications, the independent scattering approximation (ISA) is widely used to analyze light transfer in nanoparticle systems. However, the traditional independent scattering criterion is obtained under the assumption that the host medium surrounding particles is nonabsorbing, and thus may be invalid in certain circumstances. In this work, to explore the applicability of the ISA for small particles in absorbing host media, we calculate the extinction efficiency of particle clusters by direct solutions of macroscopic Maxwell equations. Using the far-field and distance-independent definitions of extinction, the computational efficiency multi-sphere method is applied for particle clusters in absorbing host, and its accuracy is verified with the discrete dipole approximation method. It is well known that for small particles, the dependent scattering in transparent host always enhances the extinction of the cluster and the criterion for the ISA is nearly independent of the particle refractive index and particle size. We show, however, that when the host medium is absorbing, the dependent scattering between particles can lead to a decreased or even negative extinction, and thus the ISA criterion depends on the particle refractive index, size, and host medium absorption index. In this result, the generalized criteria for absorbing host media may differ significantly from the conventional ones for transparent host media. The results can provide guidance in solving problems related to light transfer in nanoparticle systems, particularly in the presence of absorption in the host medium.
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Wang, Steve C., and Ling Zhong. "Estimating the number of pulses in a mass extinction." Paleobiology 44, no. 2 (February 12, 2018): 199–218. http://dx.doi.org/10.1017/pab.2016.30.
Анотація:
AbstractThe Signor-Lipps effect states that even a sudden mass extinction will invariably appear gradual in the fossil record, due to incomplete fossil preservation. Most previous work on the Signor–Lipps effect has focused on testing whether taxa in a mass extinction went extinct simultaneously or gradually. However, many authors have proposed scenarios in which taxa went extinct in distinct pulses. Little methodology has been developed for quantifying characteristics of such pulsed extinction events. Here we introduce a method for estimating the number of pulses in a mass extinction, based on the positions of fossil occurrences in a stratigraphic section. Rather than using a hypothesis test and assuming simultaneous extinction as the default, we reframe the question by asking what number of pulses best explains the observed fossil record.Using a two-step algorithm, we are able to estimate not just the number of extinction pulses but also a confidence level or posterior probability for each possible number of pulses. In the first step, we find the maximum likelihood estimate for each possible number of pulses. In the second step, we calculate the Akaike information criterion and Bayesian information criterion weights for each possible number of pulses, and then apply ak-nearest neighbor classifier to these weights. This method gives us a vector of confidence levels for the number of extinction pulses—for instance, we might be 80% confident that there was a single extinction pulse, 15% confident that there were two pulses, and 5% confident that there were three pulses. Equivalently, we can state that we are 95% confident that the number of extinction pulses is one or two. Using simulation studies, we show that the method performs well in a variety of situations, although it has difficulty in the case of decreasing fossil recovery potential, and it is most effective for small numbers of pulses unless the sample size is large. We demonstrate the method using a data set of Late Cretaceous ammonites.
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Daley, D. J., David M. Hull, and James M. Taylor. "Bisexual Galton–Watson branching processes with superadditive mating functions." Journal of Applied Probability 23, no. 3 (September 1986): 585–600. http://dx.doi.org/10.2307/3213999.
Анотація:
For a bisexual Galton–Watson branching process with superadditive mating function there is a simple criterion for determining whether or not the process becomes extinct with probability 1, namely, that the asymptotic growth rate r should not exceed 1. When extinction is not certain (equivalently, r > 1), simple upper and lower bounds are established for the extinction probabilities. An example suggests that in the critical case that r = 1, some condition like superadditivity is essential for ultimate extinction to be certain. Some illustrative numerical comparisons of particular mating functions are made using a Poisson offspring distribution.
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Daley, D. J., David M. Hull, and James M. Taylor. "Bisexual Galton–Watson branching processes with superadditive mating functions." Journal of Applied Probability 23, no. 03 (September 1986): 585–600. http://dx.doi.org/10.1017/s0021900200111763.
Анотація:
For a bisexual Galton–Watson branching process with superadditive mating function there is a simple criterion for determining whether or not the process becomes extinct with probability 1, namely, that the asymptotic growth rate r should not exceed 1. When extinction is not certain (equivalently, r > 1), simple upper and lower bounds are established for the extinction probabilities. An example suggests that in the critical case that r = 1, some condition like superadditivity is essential for ultimate extinction to be certain. Some illustrative numerical comparisons of particular mating functions are made using a Poisson offspring distribution.
Дисертації з теми "Extinction criterion":
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Zalduendo, Vidal Nicolás Mauricio. "Processus de branchement bi-sexués multi-types." Electronic Thesis or Diss., Université de Lorraine, 2023. http://www.theses.fr/2023LORR0285.
Анотація:
Le processus de Galton-Watson bi-sexué, introduit par Daley, est une extension du processus de Galton-Watson classique, décrivant l'accouplement de femelles et de mâles, formant des couples capables de se reproduire. Des propriétés telles que des conditions d'extinction et le comportement asymptotique ont été étudiées au cours des dernières années dans le cas uni-type, mais les versions multi-types n'ont été traitées que dans certains cas particuliers. Dans cette thèse, nous développons une version multidimensionnelle générale du modèle de Daley, où nous considérons différents types de femelles et de mâles, qui s'accouplent selon une “fonction d'appariement”. Nous supposons que cette fonction est superadditive, ce qui signifie simplement que deux groupes de femelles et de mâles forment un plus grand nombre de couples ensemble plutôt que séparément. L'une des principales difficultés dans l'étude de ce processus est que, contrairement au processus de Galton-Watson classique (asexué), l'opérateur associé au processus n'est pas linéaire mais concave. Pour surmonter ce problème, nous utilisons une théorie de Perron-Frobenius pour les opérateurs concaves, qui garantit l'existence d'éléments propres pour notre opérateur. Dans cette thèse, nous démontrons des lois des grands nombres et établissons des conditions nécessaires et suffisantes pour l'extinction presque sûre du processus. Nous étudions également, à travers l'identification d'une surmartingale, la convergence du processus en temps long dans le cas surcritique ainsi que l'existence de distributions quasi-stationnaires pour le régime sous-critique. Enfin, quelques extensions à des modèles avec une fonction d'appariement aléatoire et des modèles en temps continu sont traitéesThe bisexual Galton-Watson process, introduced by Daley, is an extension of the classical Galton-Watson process, but taking into account the mating of females and males, which form couples that can accomplish reproduction. Properties such as extinction conditions and asymptotic behaviour have been studied in the past years in the single-type case, but multi-type versions have only been treated in some particular cases. In this thesis we deal with a general multi-dimensional version of Daley's model, where we consider different types of females and males, which mate according to a “mating function”. We consider that this function is superadditive, which in simple words implies that two groups of females and males will form a larger number of couples together rather than separate. One of the main difficulties in the study of this process is the absence of a linear operator that is the key to understand its behavior in the asexual case, but in our case it turns out to be only concave. To overcome this issue, we use a concave Perron-Frobenius theory which ensures the existence of eigen-elements for some concave operators. Using this tool, we find a necessary and sufficient condition for almost sure extinction as well as laws of large numbers. We also study the convergence of the process in the long-time through the identification of a supermartingale, and the existence of quasi-stationary distributions for the subcritical regime. Finally, some extensions to models with random mating function and models in continuous time are considered
Книги з теми "Extinction criterion":
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Garnett, Stephen, Judit Szabo, and Guy Dutson. Action Plan for Australian Birds 2010. CSIRO Publishing, 2011. http://dx.doi.org/10.1071/9780643103696.
Анотація:
The Action Plan for Australian Birds 2010 is the third in a series of action plans that have been produced at the start of each decade. The book analyses the International Union for Conservation of Nature (IUCN) status of all the species and subspecies of Australia's birds, including those of the offshore territories. For each bird the size and trend in their population and distribution has been analysed using the latest iteration of IUCN Red List Criteria to determine their risk of extinction.
The book also provides an account of all those species and subspecies that are or are likely to be extinct. The result is the most authoritative account yet of the status of Australia's birds.
In this completely revised edition each account covers not only the 2010 status but provides a retrospective assessment of the status in 1990 and 2000 based on current knowledge, taxonomic revisions and changes to the IUCN criteria, and then reasons why the status of some taxa has changed over the last two decades. Maps have been created specifically for the Action Plan based on vetted data drawn from the records of Birds Australia, its members and its partners in many government departments.
This is not a book of lost causes. It is a call for action to keep the extraordinary biodiversity we have inherited and pass the legacy to our children.
2012 Whitley Award Commendation for Zoological Resource.
Частини книг з теми "Extinction criterion":
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Jones, A. F., and J. A. King-Hele. "An Extinction Criterion for a Catalytic Wall Reactor." In European Consortium for Mathematics in Industry, 199–202. Wiesbaden: Vieweg+Teubner Verlag, 1992. http://dx.doi.org/10.1007/978-3-663-09834-8_38.
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Welchman, Jennifer. "Does Justice Require De-extinction of the Heath Hen?" In The International Library of Environmental, Agricultural and Food Ethics, 513–32. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-63523-7_28.
Анотація:
AbstractIt is often argued that we “owe it” to species driven to extinction “to bring them back.” Can justice really require us to make restitution for anthropogenic extinctions? Can it require de-extinction? And if so, can justice require us to attempt the North American Heath Hen’s de-extinction? I will first review the types of de-extinction technologies currently available. I will then discuss the criteria used to determine when restitution is owed for injuries as well as the special challenges arising when (i) victims are wild animals and (ii) are extinct. After arguing that restitution may be due for some extinctions and that de-extinction would sometimes be an appropriate means, I apply these arguments to the case of the Heath Hen.
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Rowe, Andy. "Evaluation at the Endgame: Evaluating Sustainability and the SDGs by Moving Past Dominion and Institutional Capture." In Transformational Change for People and the Planet, 207–21. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-030-78853-7_14.
Анотація:
AbstractThree facts underlay this chapter. First, the human system and all our ambitions for improving the human system depend on sustainable natural systems. Second, we do not have much time. On track to fall well short of all sustainability goals, the climate and sustainability crises grow and extinction looms. Third, up to this point evaluation has shown little interest in sustainability, yet evaluation potentially addresses the very questions that are central to informing and guiding rapid adaptation of human behavior to successfully surmounting extinction.Business-as-usual evaluation will not suffice. At the endgame with extinction looming, we need an evaluation that is more nimble, keeps up with rapidly accelerating knowledge, is relentlessly use-seeking and that guides the way to joined-up approaches. The evaluation we need will systematically mainstream sustainability across all evaluations and interventions, in all evaluation criteria and standards. For this, all evaluations will always address nexus where human and natural systems join and incorporate knowledge and methods from both systems. Existing evaluation knowledge is well suited to this task, as are knowledges in biophysical sciences. We know and promote knowledge processes for integrative evaluation and are starting to shift toward the requirements for evaluation at the nexus. As this chapter shows, the anchors holding us back are political, not technical.
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Wienhues, Anna, and Anna Wienhues. "The Community of Justice." In Ecological Justice and the Extinction Crisis, 51–72. Policy Press, 2020. http://dx.doi.org/10.1332/policypress/9781529208511.003.0003.
Анотація:
This chapter analyses the question of how one can move from claims about moral considerability to claims about justice. Moral considerability is a necessary, but not sufficient, criterion for being a holder of entitlements of justice. Taking it as a premise that all living beings are morally considerable, the chapter proposes that a grounded justification for interspecies justice in terms of just biological conservation requires an additional four-step argumentative process as a method for including all wild living nonhuman beings in the community of justice. It claims that humans and wild nonhuman living beings constitute a community of justice which can be called a community of fate. Because moral considerability alone is not able to ground the more specific claim that duties of justice are owed to a certain entity, the theoretical move towards grounding a community of justice is a crucial feature of accounts of ecological justice.
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Subbotina, I. R., V. B. Kazansky, F. C. Jentoft, and R. Schlögl. "IR extinction coefficients as a criterion for chemical activation upon adsorption: propene interaction with cationic forms of y zeolite." In Zeolites and related materials: Trends, targets and challenges, Proceedings of the 4th International FEZA Conference, 849–52. Elsevier, 2008. http://dx.doi.org/10.1016/s0167-2991(08)80021-3.
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Wienhues, Anna. "Who Owns the Earth?" In Ecological Justice and the Extinction Crisis, 159–76. Policy Press, 2020. http://dx.doi.org/10.1332/policypress/9781529208511.003.0008.
Анотація:
This chapter outlines an implication that a commitment to ecological justice has for theorising environmental justice. One necessary, but not sufficient, criterium for achieving compatibility between the author's framework of ecological justice and theories of social justice between humans is that theories of justice must be based on the premise that the Earth is originally unowned. Thus, the chapter develops a critique of the notion of humanity's original ownership of the Earth that has been influential throughout the history of political thought. The critique of this notion can be seen as an extension of the critical investigation of some environmental ethicists on the relationship between ownership and animals, as well as contributing to a necessary 'denaturalisation' of assumptions within political thought that 'Otherise' the nonhuman. Attributing original ownership of the Earth to humans only creates a similar problematic power asymmetry between agents that matter and objects that cannot own and can potentially even be owned. Such philosophical theories exhibit a form of theoretical exclusion of an Other, which is nonhuman living beings in this case. The problem is that such perspectives exclude nonhumans from mattering in theory which can then translate into not mattering in practice.
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Kendal, Evie. "Desire, Duty, and Discrimination." In Reclaiming Space, 289—C24P48. Oxford University Press, 2023. http://dx.doi.org/10.1093/oso/9780197604793.003.0024.
Анотація:
Abstract “Desire, Duty, and Discrimination: Is There an Ethical Way to Select Humans for Noah’s Ark?” discusses ethical issues related to reproduction in space. Confined on Earth, humanity is vulnerable to extinction-level disasters such as catastrophic climate change or asteroid impact hazards. One method of preserving the species from these threats is to establish off-world settlements on other planets. This project will inevitably entail selecting members of the species (and potentially human embryos) from a broad range of candidates, necessitating the development of appropriate selection criteria. This chapter considers relevant ethical issues as they apply to this extreme “Noah’s Ark” example, considering the benefits of preserving diversity in the human population, including for different abilities, sexual orientations, and concepts of family, before interrogating whether there is a coherent method of imposing a duty to procreate in the face of species extinction and if so, how far this duty extends.
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"Invasive Asian Carps in North America." In Invasive Asian Carps in North America, edited by John L. Teem and Juan B. Gutierrez. American Fisheries Society, 2011. http://dx.doi.org/10.47886/9781934874233.ch16.
Анотація:
<em>Abstract</em>.—The directed extinction of an exotic fish population is proposed using a genetic approach to drastically reduce the ratio of females to males within the population. In the proposed strategy, sex-reversed female fish containing two Y chromosomes (Fyy) are introduced into a normal fish population. The frequencies of each of the four expected genotypes of fish in the simulated population (Fxx, Fyy, Mxy, and Myy) were modeled with a set of coupled ordinary differential equations. The equations take into account birth rate, death rate, and a fixed carrying capacity of the system. Using computer-generated simulations, it was determined that the continuous introduction of a relatively small proportion of Fyy females to the normal population leads to extinction of the exotic fish over time. The proposed eradication strategy is relevant to fish species with an XY sex-determination system that tolerate a YY genotype. Published literature suggests that Asian carps are likely to fulfill these criteria. However, technical barriers associated with sex reversal in Asian carps presently exist and must be overcome before implementation of a YY eradication strategy for Asian carps can be considered in practice. An idealized theoretical model for the eradication of Asian carps is thus presented.
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"Invasive Asian Carps in North America." In Invasive Asian Carps in North America, edited by John L. Teem and Juan B. Gutierrez. American Fisheries Society, 2011. http://dx.doi.org/10.47886/9781934874233.ch16.
Анотація:
<em>Abstract</em>.—The directed extinction of an exotic fish population is proposed using a genetic approach to drastically reduce the ratio of females to males within the population. In the proposed strategy, sex-reversed female fish containing two Y chromosomes (Fyy) are introduced into a normal fish population. The frequencies of each of the four expected genotypes of fish in the simulated population (Fxx, Fyy, Mxy, and Myy) were modeled with a set of coupled ordinary differential equations. The equations take into account birth rate, death rate, and a fixed carrying capacity of the system. Using computer-generated simulations, it was determined that the continuous introduction of a relatively small proportion of Fyy females to the normal population leads to extinction of the exotic fish over time. The proposed eradication strategy is relevant to fish species with an XY sex-determination system that tolerate a YY genotype. Published literature suggests that Asian carps are likely to fulfill these criteria. However, technical barriers associated with sex reversal in Asian carps presently exist and must be overcome before implementation of a YY eradication strategy for Asian carps can be considered in practice. An idealized theoretical model for the eradication of Asian carps is thus presented.
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Vickers, Peter. "Do We Know How the Dinosaurs Died?" In Identifying Future-Proof Science, 164—C7.P113. Oxford University PressOxford, 2022. http://dx.doi.org/10.1093/oso/9780192862730.003.0007.
Анотація:
Abstract It has been argued that we can identify future-proof science via scientific consensus, with criteria that must be met. But actually applying those criteria to a specific case can sometimes be extremely challenging; how is one to ascertain whether there is a 95 per cent consensus in the relevant community of experts? An instructive contemporary case concerns the claim that an asteroid impact caused the dinosaur extinction. Many scientists have been tempted to state the claim as a fact, and in 2010 a review article was published in Science hinting at a consensus. There was a significant community reaction to this piece, however. In addition, there has been plenty of opposition to the claim in both the published literature and activity at (some) major conferences. This chapter navigates some of the challenges that can arise when we ask after the strength of feeling in the relevant scientific community vis-à-vis a specific claim.
Тези доповідей конференцій з теми "Extinction criterion":
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Dotta, Fernando, Eduardo Hippert, and Claudio Ruggieri. "A Failure Assessment Procedure for Cracked Pipelines Incorporating a Damage Criterion for Crack Growth." In ASME 2004 23rd International Conference on Offshore Mechanics and Arctic Engineering. ASMEDC, 2004. http://dx.doi.org/10.1115/omae2004-51031.
Анотація:
This study extends a micromechanics approach based upon the computational cell methodology to model ductile crack extension of longitudinal crack-like defects in a high strength pipeline steel. Laboratory testing of an API 5L X60 AND x70 pipeline steel at room temperature using standard, deep crack C(T) specimens provide the data needed to measure the crack growth resistance curve for the material. In the computational cell model, ductile crack extension occurs through void growth and coalescence (by cell extinction) within a thin layer of material ahead of crack tip. A simple scheme to calibrate material-specific parameters for the cells is also described. A central focus of the paper is the application of the cell methodology to predict experimentally measured burst pressures for pre-cracked pipe specimens with different crack sizes. The experimental program includes longitudinally precracked pipe specimens with 8 5/8” (209 mm) and 20” (508 mm) O.D. The numerical simulations demonstrate the effectiveness of the cell approach to describe crack growth response and to predict the burst pressure for the tested pipes.
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Souza, Diogo, Eline Martins, and Eduardo C. Dalcin. "Assessing the risk of extinction of Brazil's flora: A computational approach based on microservices and geospatial analysis." In VII Workshop de Computação Aplicada à Gestão do Meio Ambiente e Recursos Naturais. Sociedade Brasileira de Computação - SBC, 2020. http://dx.doi.org/10.5753/wcama.2016.9545.
Анотація:
This paper describes a computational tool developed to assess the risk of extinction of flora according to the “B” of the IUCN Red List Categories and Criteria System. The tool consists of a set of systems arranged in a microservices architecture and performs geospatial analysis in a significant set of data in an automated manner, with relatively low computational cost.
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Frolov, V. Ya, D. Y. Ivanov, G. V. Podporkin, and A. D. Sivaev. "Development of mathematical model of processes in multi-chamber arrester for identification of criteria of arc extinction." In 2017 International Symposium on Lightning Protection (XIV SIPDA). IEEE, 2017. http://dx.doi.org/10.1109/sipda.2017.8116930.
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Hoffmann, S., B. Lenze, and H. Eickhoff. "Results of Experiments and Models for Predicting Stability Limits of Turbulent Swirling Flames." In ASME 1997 International Gas Turbine and Aeroengine Congress and Exhibition. American Society of Mechanical Engineers, 1997. http://dx.doi.org/10.1115/97-gt-396.
Анотація:
Swirling flames are used in many industrial applications like process furnaces, boilers and gas turbines due to their excellent mixing, stability, emission and burnout characteristics. The wide-spread use of swirl burners in the process and energy industries and, in particular, new concepts for the reduction of NOx-emissions raise the need for simple-to-use models for predicting lean stability limits of highly turbulent flames stabilized by internal recirculation. Based on recently published experimental data of the first author concerning the reaction structures of swirling flames operating near the extinction limit, different methods for predicting lean blow-off limits have been developed and tested. The aim of the investigations was to find stabilization criteria that allow predictions of blow-off limits of highly turbulent recirculating flames without the requirement for measurements in those flames. Several similarity criteria based on volumetric flow rates, burner size and material parameters of the cold gases, were found to be capable of predicting stability limits of premixed and (in some cases) nonpremixed flames at varying swirl intensities, burner scales and fuel compositions. A previously developed numerical field model, combining a k,ϵ-model with a combined “assumed-shape Joint-PDF”/Eddy-Dissipation reaction model was also tested for its potential for stability prediction.
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Van De Riet, Keith. "CNC Milling as Foundation for Life." In 110th ACSA Annual Meeting Paper Proceedings. ACSA Press, 2022. http://dx.doi.org/10.35483/acsa.am.110.30.
Анотація:
Architectural ornament has seen a resurgence with the application of digital design and fabrication technologies. At the same time, ornament has shifted from purely symbolic function to high performance facades that conserve energy, or, in some cases, generate their own. Coupled with this high-performance metric is a renewed interest in expressive textures and articulated facades made largely possible by digital manufacturing.1,2 The tools that support these innovative designs have also found success in replicating and restoring historic structures, thus broadening their impact and relevance to the profession. Moreover, from an ecological perspective, digitally-derived ornamentation may have the potential to address the emerging crises of species extinction and habitat loss, particularly near urban areas where the cumulative surface area of buildings and hardened landscapes exceeds that of natural settings by several orders of magnitude. These architectural, urban and landscape surfaces represent an opportunity to facilitate life itself within the built environment, and in many ways, could be the designer’s greatest opportunity to include biodiversity as criteria for design of sustainable and resilient built environments.
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Nieto-Vesperinas, M., and J. M. Soto-Crespo. "Scattering from slightly rough random surfaces." In OSA Annual Meeting. Washington, D.C.: Optica Publishing Group, 1989. http://dx.doi.org/10.1364/oam.1989.wl42.
Анотація:
In this paper we study the validity of the small perturbation method for 1-D perfectly conductive random rough surfaces. We have obtained an expression for the diffuse component of the mean scattered intensity up to fourth order in powers of k0σ for S- waves (k0 = 2π/λ, a is the rms height). For P-waves it is not possible to obtain the fourth-order term. The perturbative expressions are derived from the Rayleigh hypothesis and also from the extinction theorem. In both cases the final expressions for the mean diffuse intensity are the same. Comparisons with exact numerical results and with those predicted by the Kirchhoff approximation are made. This permits us to establish some criteria on the validity of the perturbative solution, obtaining some new interesting facts. In particular, we show that the total incoherently scattered energy is the parameter that basically determines the applicability of the perturbative solution. Precise curves marking the zones of validity of the second-order perturbative intensity are drawn. Simultaneously, the shape of the diffuse halo as a function of the correlation length T, the angle of incidence θ0, and the polarization is studied at small k0σ.
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Cordier, M., A. Vandel, B. Renou, G. Cabot, M. A. Boukhalfa, and M. Cazalens. "Spark Ignition of Confined Swirled Flames: Experimental and Numerical Investigation." In ASME Turbo Expo 2013: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/gt2013-94384.
Анотація:
A swirl burner was designed to experimentally study the impact of spark location on ignition efficiency and detailed ignition scenarios until flame stabilization or blow-off were established, following experimental observations. Premixed and non-premixed configurations were investigated for the same turbulent flow, in order to evaluate the fuel heterogeneities on ignition efficiency. Attention was paid to providing accurate data on cold flow velocity field statistics (obtained by stereoscopic PIV) and fuel mole fraction field statistics (obtained by PLIF on acetone). Ignition probability maps were established for all conditions by using laser-induced spark for a constant level of deposited energy. No systematic correlations were observed between local flow properties and ignition probability, which leads to the conclusion that history of the flame kernel inside the combustion chamber, must be taken into account to fully explain the ignition mechanism. From this conclusion, ignition scenarios were built using fast flame visualization and dynamic pressure record. Different steps of the ignition process were identified according to the location of the spark. In order to evaluate ignition probability according to spark location and flow conditions (velocity, turbulence and mixing), we extended the predictive model of Neophytou et al. [1], with some modifications, to examine whether it can be applied to ignition of swirling premixed flames. Flame particles are emitted by the spark and tracked in the flow with a Langevin equation by using non-reactive velocity fields obtained by PIV. Physical criteria are proposed to represent flame particles generation, expansion and extinction. Results indicate a relatively good agreement with the experimental database and the ignition scenarios are also well reproduced.
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Bross, Benjamin. "The Taxonomy of Spatial Typologies: A Proposal for an Analytical Language." In 108th Annual Meeting Proceedings. ACSA Press, 2020. http://dx.doi.org/10.35483/acsa.am.108.80.
Анотація:
As the phenomenon of globalization permeates across political and socio-cultural boundaries, one of its major effects is an increasingly homogenized spatial landscape. Lefebvre noted spatial production is “secreted” cultural production, so globalization is tantamount to an increasingly homogenized world culture. Designers who push back on spatial globalization eschew Modernism’s break from the past or Post-Modernism’s poly-narrative but literal u-topic emphasis, utilizing a design approach based on site-specific contextual and historic factors ranging from climate to socio-culturally produced typologies. Spatial typologies are synchronous with spatial production: their emergence, evolution and extinction exemplify a society’s material culture at specific places and times. e.g., nearly 46 centuries ago, Egyptian pyramids emerged as the salient funerary typology; thousands of years later, department stores typified the logic of capital, as the Industrial Revolution produced spaces that addressed the consumer demands of a growing bourgeoisie class. The emergence of Post-Modernism in arts and social sciences in the 1960s signaled a more liberating design approach because it embraced alternative design directions, including the reincorporation of traditional praxes of spatial production such as typologies. Rudofsky, in Architecture without Architects, reminded us that spatial production was not the exclusive domain of the formally trained designer but, more importantly, that vernacular space itself was a legible representation of a society’s values; typologies were once again important and merited documenting. Later, Pevsner noted in A History of Building Types “there is…no history of building types in existence.” Emulating the science of taxonomy, the paper proposes systematic criteria for identifying and categorizing typologies. In this approach, emphasis is placed on tracing changes in spatial morphologies over time, such that spatial relationships are revealed between earlier antecedent typologies and their contemporary iterations. This is possible because, like genetics, typologies reveal qualifying components that may illustrate iterative mutations, revealing “evolutionary drifts” or “selection processes.”